阅读说明：本技术 三维打印 (Three-dimensional printing ) 是由 K·瑙卡 T·安东尼 于 2017-10-30 设计创作，主要内容包括：在三维(3D)打印方法的一个实例中,施加金属构建材料。在金属构建材料的至少一部分上选择性施加包含金属盐的图案化流体。在施加附加的构建材料之前,使金属构建材料暴露于光照射以使金属盐达到热分解温度并热分解成金属。在暴露过程中,使金属构建材料保持低于金属构建材料的烧结温度。(In one example of a three-dimensional (3D) printing method, a metallic build material is applied. A patterning fluid comprising a metal salt is selectively applied over at least a portion of the metal build material. Prior to applying additional build material, the metal build material is exposed to light radiation to cause the metal salt to reach a thermal decomposition temperature and thermally decompose to metal. During the exposing, the metal build material is maintained below a sintering temperature of the metal build material.)

1. A three-dimensional (3D) printing method, comprising:

applying a metallic build material;

selectively applying a patterning fluid on at least a portion of the metal build material, the patterning fluid comprising a metal salt; and

exposing the metal build material to light radiation to cause the metal salt to reach a thermal decomposition temperature and thermally decompose to metal prior to applying additional build material, wherein during the exposing, the metal build material is maintained below a sintering temperature of the metal build material.

2. The method as claimed in claim 1, wherein the thermal decomposition of the metal salt comprises a series of chemical reactions, each occurring at a respective reaction temperature, and wherein the method further comprises adjusting the light irradiation energy to reach the respective reaction temperature associated with each chemical reaction.

3. The method as recited in claim 1, wherein the thermal decomposition of the metal salt into a metal comprises:

thermal decomposition reaction to produce metal oxide; and

reduction to reduce the metal oxide and produce the metal.

4. The method as recited in claim 1, wherein prior to applying additional build material, the method further comprises adjusting light illumination to induce diffusion mixing of the metal with the metal build material, adjusting a rate of diffusion mixing of the metal with the metal build material, or a combination thereof.

5. The method as recited in claim 1, wherein the metal salt is a hydrated metal salt, and wherein prior to exposing the metal build material to light radiation to cause the metal salt to reach a thermal decomposition temperature and thermally decompose to a metal, the method further comprises exposing the metal build material to light radiation to cause the hydrated metal salt to reach a dehydration temperature and dehydrate to a dehydrated metal salt.

6. The method as recited in claim 1, wherein the exposing of the metallic build material to light radiation is accomplished in an environment containing an inert gas, a reducing gas, or a combination thereof.

7. The method as recited in claim 1, wherein the metal salt is selected from the group consisting of copper nitrate, copper formate, copper sulfate, copper oxalate, nickel nitrate, nickel formate, nickel sulfate, nickel oxalate, nickel acetate, nickel thiocyanate, iron nitrate, iron sulfate, iron oxalate, iron acetate, manganese nitrate, manganese formate, manganese oxalate, cobalt nitrate, cobalt formate, cobalt sulfate, cobalt oxalate, cobalt thiocyanate, chromium nitrate, chromium sulfate, magnesium acetate, magnesium sulfate, neodymium nitrate, vanadium sulfate, vanadyl sulfate, zirconium nitrate, zinc sulfate, silver nitrate, yttrium nitrate, and combinations thereof.

8. The method as recited in claim 1, wherein the exposure of the metallic build material to light illumination is accomplished with a xenon flash lamp.

9. A three-dimensional (3D) printing method, comprising:

applying a metallic build material;

selectively applying a patterning fluid on at least a portion of the metal build material, the patterning fluid comprising a metal salt;

exposing the metallic build material to light illumination to cause:

the metal salt reaches a thermal decomposition temperature and thermally decomposes to a metal; and

the metal is diffusion mixed with the metal build material;

wherein the metal bonds the metal build material in at least the portion to form an intermediate component layer, wherein during the exposing, the metal build material is maintained below a sintering temperature of the metal build material; and

repeating the applying of the metal build material, the selectively applying of the patterning fluid, and the exposing of the metal build material to light illumination.

10. The method as recited in claim 9, wherein:

prior to the repeating, the method further includes exposing the metallic build material to additional light radiation sufficient to sinter the metallic build material in at least the portion; and

The repeating includes application of the metal build material, selective application of the patterning fluid, and exposure of the metal build material to light irradiation and additional light irradiation, thereby forming a final part.

11. The method as recited in claim 9, wherein the repeating forms an intermediate component, and wherein the method further comprises:

subjecting the intermediate component to a take-out process to separate the intermediate component from any unpatterned metallic build material; and

heating the intermediate component to a sintering temperature to form a final component.

12. The method as recited in claim 11, wherein the heating of the intermediate component to form the final component is accomplished over a period of about 1 hour to about 24 hours and in an environment containing an inert or reducing gas.

13. The method as claimed in claim 9, wherein the thermal decomposition of the metal salt comprises a series of chemical reactions, each occurring at a respective reaction temperature, and wherein the method further comprises adjusting the light irradiation energy to reach the respective reaction temperature associated with each chemical reaction.

14. A three-dimensional (3D) printing method, comprising:

applying a metallic build material;

Selectively applying a patterning fluid on at least a portion of the metal build material, the patterning fluid comprising a metal salt;

a series of light irradiation sequences were performed as follows:

exposing the metallic build material to a first sequence of light exposures to cause the metal salt to reach a thermal decomposition temperature and thermally decompose to a metal oxide;

exposing the metallic build material to a second sequence of light exposures to bring the metal oxide to a reduction temperature and to a metal; and

exposing the metal build material to a third light irradiation sequence to adjust a rate of diffusion mixing of the metal with the metal build material, wherein the metal bonds the metal build material in at least the portion to form an intermediate part layer, and wherein during the series of light irradiation sequences the metal build material is maintained below a sintering temperature of the metal build material;

then, repeating the applying of the metallic build material, the selectively applying of the patterning fluid, and the performing of the series of light irradiation sequences to form an intermediate component;

subjecting the intermediate component to a take-out process to separate the intermediate component from any unpatterned metallic build material; and

Heating the intermediate component to a sintering temperature to form a final component.

15. The method as set forth in claim 14 wherein the metal salt is a hydrated metal salt selected from the group consisting of copper nitrate trihydrate, copper formate tetrahydrate, copper sulfate pentahydrate, copper oxalate hemihydrate, nickel nitrate hexahydrate, nickel formate dihydrate, nickel sulfate heptahydrate, nickel oxalate dihydrate, nickel acetate tetrahydrate, iron nitrate nonahydrate, iron sulfate heptahydrate, iron oxalate dihydrate, iron acetate tetrahydrate, manganese nitrate tetrahydrate, manganese formate dihydrate, manganese oxalate dihydrate, cobalt nitrate hexahydrate, cobalt formate dihydrate, cobalt sulfate heptahydrate, cobalt oxalate dihydrate, chromium nitrate nonahydrate, chromium sulfate hexahydrate, magnesium acetate tetrahydrate, magnesium sulfate heptahydrate, neodymium nitrate hexahydrate, vanadyl sulfate pentahydrate, zinc nitrate hexahydrate, zinc sulfate heptahydrate, yttrium nitrate hexahydrate, and combinations thereof.

Brief Description of Drawings

Features of examples of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to similar, but possibly different, components. For the sake of brevity, reference numerals or features having a previously described function may or may not be described in connection with other drawings in which they appear.

FIG. 1 is a flow chart illustrating one example of a 3D printing method disclosed herein;

fig. 2 is a flow chart illustrating another example of a 3D printing method disclosed herein;

3A-3F are schematic and partial cross-sectional cut views depicting the formation of a 3D part using one example of a 3D printing method disclosed herein;

FIG. 4 is a graph of copper nitrate trihydrate in synthesis gas (96 wt% N)₂And 4% by weight of H₂) Normalized weight values are shown on the y-axis and the temperature to which the sample is heated (in degrees c) is shown on the x-axis;

FIG. 5 is a flow chart illustrating another example of a 3D printing method disclosed herein;

fig. 6 is a schematic and partial cross-sectional view of one example of a 3D printing system disclosed herein;

fig. 7A-7C are black and white copies of a raw color photograph showing examples of the patterning fluid disclosed herein at different stages of a series of light irradiation sequences in an inert gas environment;

FIGS. 8A-8C are black and white copies of a raw color photograph showing examples of patterned fluids at different stages of a series of light irradiation sequences in a reducing gas environment;

FIGS. 9A through 9D are black and white copies of a native color photograph showing examples of a patterned layer of build material before (9A and 9C) and after (9B and 9D) two different light illumination sequences; and

fig. 10A-10D are black and white copies of a native color photograph showing other examples of patterned layers of build material before (10A and 10C) and after (10B and 10D) two different light illumination sequences.

Detailed description of the invention

In some examples of three-dimensional (3D) printing, a patterned fluid is selectively applied to a layer of metallic build material (also referred to as build material particles) and then another layer of metallic build material is applied thereon. A patterning fluid may be applied to this further layer of build material and these processes may be repeated to form green body parts (greenplates)/green bodies (green bodies) of the 3D part to be finally formed (the "green" part of such term does not imply a colour, but rather means that the part has not been fully machined). The patterning fluid can include a binder that binds the metallic build material particles of the green part together. After forming the green part, the green part can be removed from the unpatterned build material and exposed to heat to sinter the metal build material in the green part to form the final 3D object with sufficient density.

The mechanical strength of the green part can affect the ability to remove the green part from the unpatterned metal build material. If the green part does not have sufficient mechanical strength, it may not withstand cleaning (e.g., with a brush and/or air jets). If the green part is not clean or not sufficiently clean, some unpatterned metal build material may remain on the intermediate part surface. The unpatterned build material remaining on the green part surface (when the intermediate part is exposed to heat to sinter the build material to form the final 3D part) can affect the accuracy and quality of the formed part. In some cases, the intermediate part, which is mechanically weak, may be damaged during the removal process. Such damage may be visible on the final part formed, which is undesirable. Alternatively, a new green part must be printed to replace the damaged green part, which can be expensive and/or time consuming.

In some cases, after printing the green body part but before removing from the unpatterned build material, the green body part along with the entire unpatterned build material volume can be subjected to a heat treatment to strengthen the green body part. Such heat treatment increases the time and cost of the additive manufacturing process.

Additionally, post-processing of the green part may involve removing the binder (used to bond the metal build material particles of the green part together) by dissolution or by burning off as part of the sintering process. If some of the adhesive is not removed, they may interfere with the integrity of the final 3D object. However, binder removal may increase the time of the 3D printing process and/or introduce additional chemicals (e.g., to dissolve the binder). In addition, removing gaseous byproducts (produced by decomposition of the adhesive) from one or more areas below the surface of the 3D object may be challenging and/or may limit the size of the printable 3D object.

Rather than forming green parts in the manner described above, examples of the 3D printing methods disclosed herein employ a layer-by-layer patterning and light irradiation sequence (light irradiation sequencing) method that improves the bonding strength of the layers as they are printed. Patterning uses a patterning fluid containing dissolved or dispersed metal salts, and the sequence of light irradiation induces one or more chemical reactions during printing of the layers to thermally decompose the metal salts and form the metal (e.g., via a solid state reaction or a solid and gas reaction) without causing premature sintering of the metal build material. The light irradiation sequence also causes the formed metal to diffusion mix with and bond to the metal build material. The metal formed may be in the form of nanoparticles having a particle size of about 1nm to less than 1000nm, which may allow the metal to melt at lower temperatures (compared to the metallic build material). When melted, these metal nanoparticles can wet adjacent particles of the metallic build material, which mechanically bonds the build material particles and increases the bond strength between them when printing the layers. The improved bond strength of the various layers increases the mechanical strength of the entire intermediate or final part formed in the 3D printer.

As mentioned, the metal formed in the layer-by-layer process bonds the metal build material in the patterned portions. It is to be understood that the sequence of light illumination may be controlled by correcting the intensity and/or duration of light illumination relative to the temperature of the metallic build material, and may be terminated when a desired intensity of the printed layer is achieved. As further described herein, temperature may be used as an indication of the progress of one or more reactions.

In some examples, the sequence of light irradiation is controlled to form intermediate component layers and ultimately intermediate components. The term "intermediate component" as used herein refers to a component precursor having a shape representative of the final 3D printed component and comprising metal-bonded unsintered metallic build material particles generated by at least thermal decomposition of a metal salt in a patterning fluid. It is to be understood that any metal build material particles that are not bonded by metal are not considered part of the intermediate component even if they are adjacent to or surround the intermediate component. In these examples, the metal bond formed from the metal salt provides sufficient mechanical strength to the intermediate component to enable it to be handled or to withstand removal from the build area platform without being detrimentally affected (e.g., without loss of shape, damage, etc.). Such an intact intermediate component may then be exposed to an additional annealing process, which may sinter the metallic build material to form the final component, and may also chemically convert any metal salts and/or any one or more decomposition products remaining in the intermediate component.

Thermally decomposing the metal salt layer-by-layer into metal may reduce (e.g., in making the intermediate component) sintering time in a high temperature furnace, which may reduce the cost and time of the printing process. In addition, thermally decomposing the metal salt layer-by-layer into a metal makes it easier to remove gaseous byproducts (e.g., H) than to remove them from the entire component at one time₂O、O₂、CO、CO₂Etc.)

Intermediate components in which metal build material is bonded with metal formed from decomposed metal salts can have improved strength compared to alternative binders (e.g., polymeric binders). Furthermore, the metal bond does not lose its strength during sintering, thereby enabling sintering of 3D geometries including cantilevers and unsupported beams without deformation (sagging, bending, etc.) or cracking due to gravity.

In other examples, the light irradiation sequence is performed according to one or more methods disclosed herein to form a metal bond from a metal salt without prematurely sintering the metal build material. However, in these other examples, the layers are also exposed to additional light irradiation, which sinters the patterned metal build material and forms the final component layer. The metal (resulting from thermal decomposition of the metal salt of the patterning fluid) may enhance energy absorption within the patterned portions as compared to the unpatterned portions. This additional energy may sinter the patterned metal build material, while the unpatterned metal build material does not. Additionally, the metal (generated from thermal decomposition of the metal salt of the patterning fluid) may increase the solid state diffusion path between patterned metal build materials compared to unpatterned metal build materials. The additional solid state diffusion paths (which drive sintering) may accelerate sintering of the patterned metal build material, while the unpatterned metal build material does not. This process forms one layer of the final part and may be repeated to form the final part without subsequent processing (e.g., annealing).

The term "final part" as used herein refers to a part that can be used for its intended or intended use. Examples of final components include metal binders (where the metal is generated from the thermal decomposition of a metal salt of a patterning fluid) and sintered metal build material particles that can be fused together to form a continuous body. By "continuous body" is meant that the metal build material particles are fused together with a metal binder to form a single part having sufficient mechanical strength to withstand removal from the printer without suffering deleterious effects (e.g., no loss of shape, breakage, etc.) as well as for the desired or intended use of the final part.

In addition, both the intermediate and final parts formed by examples of the methods disclosed herein have sufficient mechanical strength to withstand cleaning (e.g., with brushes and/or air jets) without being detrimentally affected.

Referring now to fig. 1, 2, and 3A-3F, examples of three-dimensional (3D) printing methods 100, 200, 300 are depicted. Prior to performing the method 100, 200, 300 or as part of the method 100, 200, 300, the controller 50 (see, e.g., fig. 6) may access data stored in the data store 52 (see, e.g., fig. 6) regarding the 3D part to be printed. The controller 50 may determine the number of layers of metallic build material 16 to be formed and the location at which the patterned fluid 20 is deposited on each layer by the applicator 24.

As shown in fig. 1, one example of a three-dimensional (3D) printing method 100 includes: applying a metallic build material 16 (reference numeral 102); selectively applying a patterning fluid 20 over at least a portion 30 of a metal build material 16, the patterning fluid 20 comprising a metal salt 22 (reference numeral 104); and exposing the metal build material 16 to light radiation to cause the metal salt 22 to reach a thermal decomposition temperature and thermally decompose to metal 22' prior to applying additional build material 16, wherein during the exposing, the metal build material 16 is maintained below a sintering temperature of the metal build material 16 (reference numeral 106).

As shown in fig. 2, another example of a three-dimensional (3D) printing method 200 includes: applying a metallic build material 16 (reference numeral 202); selectively applying a patterning fluid 20 over at least a portion 30 of a metal build material 16, the patterning fluid 20 comprising a metal salt 22 (reference numeral 204); prior to applying additional build material 16, the metallic build material 16 is exposed to light radiation to cause: the metal salt 22 reaches the thermal decomposition temperature and thermally decomposes to metal 22'; and metal 22' is diffusion mixed with metal build material 16; wherein the metal bonds the metal build material 16 in at least the portion 30 to form an intermediate component layer, wherein during the exposing, the metal build material 16 is maintained at a temperature below a sintering temperature of the metal build material 16 (reference numeral 206); and repeating the applying of the metal build material 16, the selective applying of the patterning fluid 20, and the exposing of the metal build material 16 to the light illumination (208).

As shown in reference numeral 102 in fig. 1, reference numeral 202 in fig. 2, and fig. 3A and 3B, the methods 100, 200, 300 include applying a metallic build material 16. The metallic build material 16 may be any particulate metallic material.

In one example, the metal build material 16 may have the ability to sinter into a continuous body to form the final part 42 when heated to a sintering temperature. It is to be understood that the sintering temperature may vary, depending in part on the alloy composition and phase or phases of the metallic build material 16. For example, stainless steel alloys have a sintering temperature of 800 ℃ to 1450 ℃, while aluminum alloys range from about 450 ℃ to 650 ℃.

In one example, the metallic build material 16 is a single phase metallic material composed of one element. In this example, the sintering temperature is below the melting point of the single element.

In another example, the metallic build material 16 is composed of two or more elements, which may be in the form of a single phase metal alloy or a multi-phase metal alloy. In these other examples, melting typically occurs over a range of temperatures, and the sintering temperature is below this range of temperatures.

A single element or alloy may be used as the metallic build material 16. Some examples of metal build material 16 include steel, stainless steel, bronze, titanium (Ti) and its alloys, aluminum (Al) and its alloys, nickel (Ni) and its alloys, cobalt (Co) and its alloys, iron (Fe) and its alloys, nickel-cobalt (NiCo) alloys, gold (Au) and its alloys, silver (Ag) and its alloys, platinum (Pt) and its alloys, and copper (Cu) and its alloys. Some specific examples include AlSi10Mg, 2xxx series aluminum, 4xxx series aluminum, CoCr MP1, CoCrSP2, MaragingSteel MS1, Hastelloy C, Hastelloy X, nickel alloy HX, Inconel IN625, Inconel IN718, SS GP1, SS 17-4PH, SS 316L, Ti6Al4V, and Ti-6Al-4V ELI 7. While several exemplary alloys have been provided, it is to be understood that other alloy build materials may be used.

Any metallic build material 16 that is in powder form at the beginning of the 3D printing method 100, 200, 300 may be used. Thus, the melting point, solidus temperature (where melting is induced), eutectic temperature (the temperature at which a single phase liquid completely solidifies into a two phase solid), and/or transfuse temperature (the point at which a single phase solid transitions to a two phase solid plus liquid mixture, where solids above the transfuse temperature have a different phase than solids below the transfuse temperature) of the metal build material 16 is higher than the temperature of the environment (e.g., higher than 100 ℃) in which the patterned portion of the 3D printing method 100, 200, 300 is performed. In some examples, the metal build material 16 may have a melting point of about 850 ℃ to about 3500 ℃. In other examples, the metallic build material 16 may be an alloy having a range of melting points.

The metallic build material particles 16 may be composed of similarly sized particles or differently sized particles. In the example shown herein, the metallic build material 16 includes particles of similar size. The term "size" as used herein with respect to the metal build material particles 16 refers to the diameter of a spherical particle, or the average diameter of a non-spherical particle (i.e., the average of multiple diameters across the particle), or the volume weighted average diameter of the particle distribution. In one example, the average size of the metal build material particles 16 is about 1 μm to about 200 μm. In another example, the average size of the metal build material particles 16 is about 10 μm to about 150 μm. In yet another example, the average size of the metallic build material particles 16 is 20 μm to about 90 μm. In yet another example, the average size of the metal build material particles 16 is about 40 μm.

In one example, the metal build material particles 16 may have a gaussian particle size distribution. In another example, the metal build material particles 16 may have several overlapping gaussian particle size distributions.

In the example shown in fig. 3A and 3B, applying metallic build material 16 may include using a printing system (e.g., printing system 10 shown in fig. 6). The printing system may include a build area platform 12, a build material supply 14 containing metal build material particles 16, and a build material distributor 18.

Build area platform 12 receives metallic build material 16 from build material supply 14. The build area platform 12 may be moved in the direction indicated by arrow 34, for example along the z-axis, to enable delivery of the metal build material 16 onto the build area platform 12 or onto a previously formed layer. In one example, when metallic build material particles 16 are to be transported, the build region platform 12 may be programmed to advance (e.g., downward) sufficiently so that the build material distributor 18 can push the metallic build material particles 16 onto the build region platform 12 to form a substantially uniform layer 28 of metallic build material 16 thereon. The build area platform 12 may also return to its original position, for example when a new part is to be built.

The build material supplier 14 may be a vessel, bed, or other surface that places the metallic build material particles 16 between the build material distributor 18 and the build area platform 12.

Build material distributor 18 may be moved in the direction indicated by arrow 36, e.g., along the y-axis, above build material supply 14 and across build area platform 12 to spread layer 28 of metallic build material 16 over build area platform 12. The build material distributor 18 may also return to a position proximate to the build material supply 14 after spreading the metallic build material particles 16. Build material distributor 18 can be a blade (e.g., a doctor blade), a roller, a combination of a roller and a blade, and/or any other device capable of spreading metal build material 16 over build area platform 12. For example, build material distributor 18 may be counter-rotating rollers.

Build area platform 12 (including sidewalls) and layer of build material 28 may be heated above ambient temperature by additional heaters (not shown in fig. 6).

As shown in FIG. 3A, build material supply 14 may supply metallic build material particles 16 to a location so that they are ready to be spread onto build area platform 12. The build material distributor 18 can spread the supplied metallic build material particles 16 onto the build area platform 12. The controller 50 may process control (process control) build material supply data and, in response, control the build material supplier 14 to properly place the metallic build material particles 16 and may process control the spreader data and, in response, control the build material distributor 18 to spread the supplied metallic build material particles 16 over the build area platform 12 to form the layer 28 of metallic build material 16 thereon. In other examples (not shown), the build distributor 18 may sprinkle the metallic build material particles 16 over the build area platform 12 to form a layer 28 of metallic build material 16 thereon. While several examples have been provided, it is to be understood that other techniques may also be used to substantially uniformly apply the build material particles 16. As shown in fig. 3B, one layer of build material 28 has been formed.

Layer 28 of metallic build material 16 has a substantially uniform thickness over build region platform 12. In one example, the thickness of the layer of build material 28 is about 100 μm. In another example, the thickness of the layer of build material 28 is about 30 μm to about 300 μm, although thinner or thicker layers may also be used. For example, the thickness of the layer of build material 28 may be about 20 μm to about 500 μm, or about 50 μm to about 80 μm. For finer feature definition, the layer thickness can be as low as about 2x (i.e., 2 times) the particle size (as shown in fig. 3B). In some examples, the layer thickness may be about 1.5x particle size.

As shown in reference numeral 104 in fig. 1, reference numeral 206 in fig. 2, and fig. 3B, the method 100, 200, 300 continues by selectively applying the patterning fluid 20 over at least a portion 30 of the metallic build material 16. The patterning fluid 20 comprises a metal salt 22 and a liquid carrier (liquid vehicle). In some cases, patterning fluid 20 is composed of metal salt 22 and a liquid carrier, without any other components.

When applied to the layer 28 of the metal build material 16, the liquid carrier is capable of wetting the metal build material particles 16 and the metal salt 22 is capable of penetrating into the microscopic pores/voids (i.e., spaces between the metal build material particles 16) of the layer 28 of build material.

The metal salt 22 in the patterned fluid 20 can be thermally decomposed to metal 22' by one or more thermally-induced chemical reactions. In some examples, the metal salt 22 thermally decomposes directly to the metal 22' when exposed to the thermal decomposition temperature. In other examples, the metal salt 22 is thermally decomposed to a metal oxide (not shown), which is then reduced to produce the metal 22'. In these other examples, "thermal decomposition temperature" may include several reaction temperatures, some of which correspond to the decomposition of metal salts, and others of which correspond to the reduction of metal oxides. It is to be understood that the decomposition of the metal salt to the metal oxide may occur in multiple stages, each corresponding to a different chemical decomposition reaction. In still other examples, the metal salt 22 is a hydrated metal salt. In these examples, the hydrated metal salt 22 is dehydrated to a dehydrated metal salt, which is subsequently thermally decomposed to a metal oxide, and then reduced to produce the metal 22'. In these examples, "thermal decomposition temperature" may include several reaction temperatures, some of which correspond to dehydration of the hydrated metal salt, others of which correspond to decomposition of the dehydrated metal salt, and still others of which correspond to reduction of the metal oxide. Thus, the term "thermal decomposition temperature" as used herein may include a single reaction temperature or several different reaction temperatures, depending on the metal salt 22 used.

The dehydration temperature (when applicable), decomposition temperature and reduction temperature (when applicable) can be determined by thermogravimetric analysis. These temperatures may be used to determine the appropriate sequence of light irradiation to initiate the desired chemical reaction to form the metal 22' from the metal salt 22.

Thermogravimetric analysis of copper nitrate trihydrate (in synthesis gas, 96% by weight N)₂And 4% by weight of H₂Which is a reducing gas) is shown in fig. 4. Figure 4 shows the normalized weight of a sample of initially copper nitrate trihydrate as it is progressively heated in synthesis gas at a ramp rate of 3 deg./minute. In fig. 4, the normalized weight values are shown on the y-axis and the temperature (in degrees c) to which the sample was heated is shown on the x-axis. The reduction in normalized weight of the sample shown in fig. 4 indicates the formation of different intermediates formed by a series of chemical reactions that constitute thermal decomposition. The temperature at which the normalized weight loss occurs is the reaction temperature associated with the chemical reaction. A series of chemical reactions, i.e., dehydration, decomposition and reduction, constituting the thermal decomposition of copper nitrate trihydrate is indicated in fig. 4. As shown in fig. 4, copper nitrate trihydrate may absorb sufficient energy to reach its dehydration temperature (i.e., about 155 c), then absorb sufficient energy to reach its decomposition temperature (i.e., about 250 c), and then absorb sufficient energy to reach its reduction temperature (i.e., about 295 c). Dehydration of the copper nitrate trihydrate yields anhydrous copper nitrate. The thermal decomposition of anhydrous copper nitrate can produce copper oxide, and the copper oxide Copper may be formed by the reduction.

Thermogravimetric analysis of ferric nitrate nonahydrate, heated gradually in synthesis gas at a ramp rate of 3 deg./minute, showed that ferric nitrate trihydrate could absorb enough energy to reach its dehydration temperature (i.e., about 145 deg.c), then absorb enough energy to reach its decomposition temperature (i.e., about 160 deg.c), and then absorb enough energy to reach its reduction temperature (i.e., about 590 deg.c).

The metal 22' is the reducing cation of the metal salt 22. As an example, if the metal salt 22 is copper nitrate or copper formate, the metal 22' is copper. As another example, if the metal salt 22 is nickel nitrate, the metal 22' is nickel. The metal 22' may form an at least substantially continuous network/glue that bonds the metal build material particles 16 into the intermediate member 40.

The metal salt 22 may be any metal salt that is thermally decomposable (directly or indirectly) to a metal 22' that is capable of binding the metal build material particles 16. In one example of the methods 100, 200, 300, the metal salt 22 is selected from copper nitrate (Cu (NO)₃)₂) Copper formate (C)₂H₂CuO₄) Copper sulfate (CuSO)₄) Copper oxalate (CuC)₂O₄) Nickel nitrate (Ni (NO))₃)₂) Nickel formate (C)₂H₂NiO₄) Nickel sulfate (NiSO)₄) Nickel oxalate (NiC)₂O₄) Nickel acetate (Ni (C)₂H₃O₂)₂) Nickel thiocyanate (Ni (SCN) ₂) Iron nitrate (Fe (NO)₃)₂) Iron sulfate (FeSO)₄) Iron oxalate (FeC)₂O₄) Fe (C) iron acetate₂H₃O₂)2 manganese nitrate (Mn (NO)₃)₂) Manganese formate (C)₂H₂MnO₄) Manganese oxalate (MnC)₂O₄) Cobalt nitrate (Co (NO)₃)₂) Cobalt formate (C)₂H₂CoO₄) Cobalt sulfate (CoSO)₄) Cobalt oxalate (CoC)₂O₄) Cobalt thiocyanate (Co (SCN)₂) Chromium nitrate (Cr (NO)₃)₃) Chromium sulfate (CrSO)₄) Magnesium acetate (Mg (CH)₃COO)₂) Magnesium sulfate (MgSO)₄) Neodymium nitrate (Nd (NO)₃)₃) Vanadyl sulfate (VOSO)₄) Zirconium nitrate (Zr (NO)₃)₄) Zinc nitrate (Zn (NO)₃)₂) Zinc sulfate (ZnSO)₄) Silver nitrate (Ag (NO)₃)₂) And yttrium nitrate (Y (NO)₃)₃)。

Examples of the metal salt 22 that may be a hydrated metal salt include copper nitrate trihydrate, copper formate tetrahydrate, copper sulfate pentahydrate, copper oxalate hemihydrate, nickel nitrate hexahydrate, nickel formate dihydrate, nickel sulfate heptahydrate, nickel oxalate dihydrate, nickel acetate tetrahydrate, iron nitrate nonahydrate, iron sulfate heptahydrate, iron oxalate dihydrate, iron acetate tetrahydrate, manganese nitrate tetrahydrate, manganese formate dihydrate, manganese oxalate dihydrate, cobalt nitrate hexahydrate, cobalt formate dihydrate, cobalt sulfate heptahydrate, cobalt oxalate dihydrate, chromium nitrate nonahydrate, chromium sulfate hexahydrate, magnesium acetate tetrahydrate, magnesium sulfate heptahydrate, neodymium nitrate hexahydrate, vanadyl sulfate pentahydrate, zinc nitrate hexahydrate, zinc sulfate heptahydrate, yttrium nitrate hexahydrate, and combinations thereof. Examples of the metal salt 22 that can be directly thermally decomposed into the metal 22' include copper formate, copper oxalate, nickel formate, nickel oxalate, nickel thiocyanate, and cobalt thiocyanate. Examples of metal salts 22 that thermally decompose to metal oxides (which are subsequently reduced to form metal 22') include copper nitrate, copper sulfate, nickel nitrate, nickel sulfate, nickel acetate, iron nitrate, iron sulfate, iron acetate, manganese nitrate, cobalt sulfate, chromium nitrate, chromium sulfate, magnesium acetate, magnesium sulfate, neodymium nitrate, vanadyl sulfate, zirconium nitrate, zinc sulfate, and yttrium nitrate.

It is to be understood that the metal 22' will be part of the final part 42. In one example, the metal salt 22 is selected such that the metal 22' formed therefrom is the same material as the metal build material 16. In another example, the metal salt 22 is selected such that the metal 22' formed therefrom will form an alloy with the metal build material 16.

The metal salt 22 may be present in the patterning fluid 20 in an amount from about 5 wt% to about 60 wt% (based on the total weight of the patterning fluid 20). In one example, the metal salt 22 is present in the patterning fluid 20 in an amount of about 40 wt%. It is believed that these metal salt loadings provide patterned fluid 20 with a balance between jetting reliability and bonding efficiency.

As mentioned above, the patterning fluid 20 comprises a metal salt 22 and a liquid carrier. As used herein, "liquid carrier" may refer to a liquid fluid in which the metal salt 22 is dissolved or dispersed to form the patterned fluid 20. A wide variety of liquid carriers, including aqueous and non-aqueous carriers, can be used for patterning fluid 20. In some cases, the liquid carrier consists of the principal solvent, with no other components. In other examples, the patterning fluid 20 may comprise other components, depending in part on the applicator 24 used to dispense the patterning fluid 20. Examples of other suitable patterned fluid components include one or more co-solvents, one or more surfactants, one or more antimicrobial agents, and/or one or more anti-kogation agents.

The primary solvent may be aqueous or non-aqueous (e.g., ethanol, acetone, N-methylpyrrolidone, aliphatic hydrocarbons, etc.). In some examples, patterning fluid 20 is composed of metal salt 22 and a primary solvent (no other components). In these examples, the primary solvent constitutes the balance of the patterned fluid 20.

Classes of organic cosolvents that may be used for patterning fluid 20 include aliphatic alcohols, aromatic alcohols, glycols, glycol ethers, polyglycol ethers, 2-pyrrolidinones, caprolactams, formamides, acetamides, glycols, and long chain alcohols. Examples of such co-solvents include primary aliphatic alcohols, secondary aliphatic alcohols, 1, 2-alcohols, 1, 3-alcohols, 1, 5-alcohols, 1, 6-hexanediol or other diols (e.g., 1, 5-pentanediol, 2-methyl-1, 3-propanediol, etc.), ethylene glycol alkyl ethers, propylene glycol alkyl ethers, higher homologs of polyethylene glycol alkyl ethers (C)₆-C₁₂) Triethylene glycol, tetraethylene glycol, tripropylene glycol methyl ether, N-alkyl caprolactams, unsubstituted caprolactams, substituted and unsubstituted formamides, substituted and unsubstituted acetamides, and the like. Other examples of organic cosolvents include dimethyl sulfoxide (DMSO), isopropanol, ethanol, pentanol, acetone, and the like.

Other examples of suitable co-solvents include water-soluble high boiling solvents (i.e., humectants) that have a boiling point of at least 120 ℃ or higher. Some examples of high boiling solvents include 2-pyrrolidone (i.e., 2-pyrrolidone having a boiling point of about 245 ℃), 1-methyl-2-pyrrolidone (having a boiling point of about 203 ℃), N- (2-hydroxyethyl) -2-pyrrolidone (having a boiling point of about 140 ℃), 2-methyl-1, 3-propanediol (having a boiling point of about 212 ℃), and combinations thereof.

The one or more co-solvents may be present in the patterned fluid 20 in a total amount of about 1 wt% to about 50 wt%, based on the total weight of the patterned fluid 20, depending on the jetting configuration of the applicator 24. In one example, the total amount of the one or more co-solvents present in the patterning fluid 20 is about 25 wt% based on the total weight of the patterning fluid 20.

The co-solvent or co-solvents of the patterning fluid 20 may depend in part on the jetting technique used to dispense the patterning fluid 20. For example, if thermal ink jet is used, water and/or ethanol and/or other longer chain alcohols (e.g., pentanol) can be the primary solvent (i.e., 35 wt% or more of the patterned fluid 20) and the co-solvent. For another example, if piezo inkjet is used, water may constitute about 25 wt% to about 30 wt% of patterned fluid 20, and the primary solvent (i.e., 35 wt% or more) may be ethanol, isopropanol, acetone, or the like.

In some examples, the liquid carrier includes one or more surfactants to improve jettability of the patterned fluid 20. Examples of suitable surfactants include self-emulsifiable nonionic wetting agents based on acetylenic diol chemistry (e.g., from Air Products and Chemicals, incSEF), nonionic fluorosurfactants (e.g., from DuPont)Fluorosurfactants, e.g.FS-35, formerly ZONYL FSO) andand (4) combining. In other examples, the surfactant is an ethoxylated low foaming wetting agent (e.g., from air products and Chemical inc

440 orCT-111) or ethoxylated wetting agents and molecular defoamers (e.g., from Air Products and Chemical inc

420). Still other suitable surfactants include nonionic wetting agents and molecular defoamers (e.g., from Air Products and Chemical inc104E) Or water-soluble nonionic surfactants (e.g., TERGITOL from The Dow Chemical Company)^TMTMN-6、TERGITOL^TM15-S-7 or TERGITOL^TM15-S-9 (secondary alcohol ethoxylate)). Yet another example includes anionic surfactants, such as those from the Dow Chemical Company2A1。

Whether a single surfactant or a combination of surfactants is used, the total amount of surfactant(s) in the patterning fluid 20 may be about 0.01 wt% to about 10 wt%, based on the total weight of the patterning fluid 20. In one example, the total amount of the one or more surfactants in the patterning fluid 20 may be about 3 wt% based on the total weight of the patterning fluid 20.

The liquid carrier may also comprise one or more antimicrobial agents. Suitable antimicrobial agents include biocides and fungicides. Exemplary antimicrobial agents may include NUOSEPT^TM(Troy Corp.)、UCARCIDE^TM(Dow ChemicalCo.)、B20(Thor)、M20(Thor) and combinations thereof. Examples of suitable biocides include aqueous solutions of 1, 2-benzisothiazolin-3-one (e.g., from Arch Chemicals, inc

GXL), quaternary ammonium compounds (e.g.

2250 and 2280,50-65B and

250-T, both from Lonza Ltd. Corp.) and an aqueous solution of methylisothiazolone (e.g., from Dow Chemical Co., Ltd.)MLX)。

In one example, the patterning fluid 20 may comprise a total amount of antimicrobial agent from about 0.05 wt% to about 1 wt%. In another example, the one or more antimicrobial agents are one or more biocides and are present in the patterned fluid 20 in an amount of about 0.25 wt.% (based on the total weight of the patterned fluid 20).

An anti-kogation agent may be included in the patterning fluid 20. Kogation refers to the deposition of dry ink (e.g., patterned fluid 20) on the heating elements of a thermal inkjet printhead. One or more anti-fouling agents are included to help prevent scale build-up. Examples of suitable anti-kogation agents include oleyl polyoxyethylene (3) ether phosphate (e.g., available as CRODAFOS @) ^TMO3A or Crodafos^TMN-3 acids available from Croda), or a combination of oleyl polyoxyethylene (3) ether phosphate and low molecular weight (e.g. < 5,000) polyacrylic acid polymers (e.g. as CARBOSPERSE @)^TMK-7028 Polyacrylate from Lubrizol)。

Whether a single anti-kogation agent or a combination of anti-kogation agents is used, the total amount of the one or more anti-kogation agents in the patterning fluid 20 can be from greater than 0.20 wt% to about 0.65 wt% based on the total weight of the patterning fluid 20.

In some examples, the patterning fluid 20 is free of additional energy absorbers. In the examples disclosed herein, the metal salt 22 may absorb a sufficient amount of energy to reach the dehydration temperature, the thermal decomposition temperature, and/or the reduction temperature. The formed metal 22' may enhance light absorption within the patterned region, for example by altering the emissivity of the patterned region.

As used herein, the term "free of, when referring to a component (e.g., an energy absorber), can refer to a composition that does not contain any added amount of the component, but may contain residual amounts (e.g., as impurities). This component may be present in trace amounts, and in one aspect is present in an amount less than 0.1 weight percent (wt%), based on the total wt% of the composition (e.g., patterning fluid 20), although the composition is described as "free" of this component, in other words, "free" of a component may refer to the absence of an added component, but allowing for trace amounts or impurities inherently present in certain ingredients.

It is to be understood that a single patterning fluid 20 may be selectively applied on portions 30, or multiple patterning fluids 20 may be selectively applied on portions 30. As one example, a plurality of patterning fluids 20 may be used to establish a desired alloy from the metal build material 16, the metal 22 'resulting from thermal decomposition of the metal salt 22 in one patterning fluid 20, and the metal 22' resulting from thermal decomposition of the metal salt 22 in another patterning fluid 20. As another example, a variety of patterned fluids 20 may be used to create a final part 42 having different compositions (e.g., pure metals and alloys, or first and second alloys) in different regions.

As illustrated in fig. 3B, the patterning fluid 20 may be dispensed from an applicator 24. The applicator 24 may be a thermal inkjet printhead, a piezoelectric printhead, a continuous inkjet printhead, etc., and selective application of the patterning fluid 20 may be achieved by thermal inkjet printing, piezoelectric inkjet printing, continuous inkjet printing, etc.

Controller 50 may process the data and, in response, control applicator 24 to deposit patterned fluid 20 (e.g., in the direction indicated by arrow 38) onto one or more predetermined portions 30 of build material layer 28 that are to be part of final part 42. The applicator 24 may be programmed to receive commands from the controller 50 and deposit the patterning fluid 20 according to the cross-sectional pattern of the layer of the final part 42 to be formed. As used herein, the cross-section of the layer of the final part 42 to be formed refers to the cross-section parallel to the surface of the build area platform 12. In the example shown in fig. 3B, the applicator 24 selectively applies the patterning fluid 20 on one or more portions 30 of the layer of build material 28 that is to become the first layer of the final part 42. As one example, if the 3D part to be formed is shaped like a cube or cylinder, then patterned fluid 20 is deposited on at least a portion of build material layer 28 in a square pattern or a circular pattern (top view), respectively.

As mentioned above, the patterning fluid 20 comprises a metal salt 22 and a liquid carrier. The volume of patterning fluid 20 applied per unit of metal build material 16 in patterned portion 30 may be sufficient to provide enough metal salt 22 to bond the metal build material particles 16 in patterned portion 30 together (when metal 22' is generated from thermal decomposition of metal salt 22) with sufficient mechanical strength to withstand the extraction process. The volume of patterning fluid 20 applied per unit of metal build material 16 in patterned portion 30 may depend at least in part on the metal salt 22 used, the metal salt loading in patterning fluid 20, and the metal build material 16 used.

It is to be understood that the portions 32 of the build material layer 28 to which the patterning fluid 20 is not applied also do not have the metal salt 22 introduced therein. Thus, these portions 32 do not become part of the intermediate component 40 or the final component 42 that is ultimately formed.

As shown in reference numeral 106 in fig. 1, reference numeral 206 in fig. 2, and fig. 3C, the methods 100, 200, 300 continue by exposing the metallic build material 16 to light illumination prior to applying additional build material 16.

As shown in reference numeral 106 in fig. 1, reference numeral 206 in fig. 2, and fig. 3C, the metallic build material 16 is exposed to light irradiation layer by layer to cause the metal salt 22 to reach a thermal decomposition temperature and thermally decompose to the metal 22'. In some examples of the methods 100, 200, 300, the thermal decomposition of the metal salt 22 to the metal 22' comprises a series of chemical reactions, each occurring at a respective reaction temperature, and wherein the methods 100, 200, 300 further comprise adjusting the energy of the light irradiation (e.g., by adjusting the intensity) to reach the respective reaction temperature associated with each chemical reaction. Examples of chemical reactions include dehydration (which occurs at a dehydration temperature), thermal decomposition (which occurs at a thermal decomposition temperature), and reduction (which occurs at a reduction temperature).

In one example of the methods 100, 200, 300, the thermal decomposition of the metal salt 22 to the metal 22' includes: thermal decomposition reaction to produce metal oxide; and a reduction reaction to reduce the metal oxide and produce the metal 22'.

In other examples of the methods 100, 200, 300, the metal salt 22 is a hydrated metal salt, and the methods 100, 200, 300 further include exposing the metal build material 16 to light radiation to bring the hydrated metal salt to a dehydration temperature and dehydrate to a dehydrated metal salt before exposing the metal build material 16 to light radiation to bring the metal salt 22 to a thermal decomposition temperature and thermally decompose to the metal 22'. In some examples, bringing the hydrated metal salt to a dehydration temperature and dehydrating to a dehydrated metal salt may also result in evaporation of the liquid carrier of the patterned fluid 20. Evaporation may result in some densification of patterned portion 30 of layer 28 by capillary action.

In some examples of methods 100, 200, 300, the exposure of the metal build material 16 may include performing a light irradiation sequence to bring the metal salt 22, metal oxide, or metal 22' to a desired reaction temperature (e.g., dehydration temperature, thermal decomposition temperature, reduction temperature, etc.).

In any of the examples disclosed herein, the light illumination or light illumination sequence may include a single pulse/flash or multiple pulses/flashes from the light illumination source 26, 26'. In one example, each pulse/flash may emit light having about 0.5J/cm ²To about 50J/cm²Is irradiated with light of energy of, andand each pulse/flash may be greater than 0ms to about 50ms in length. It is to be understood that the energy may vary depending on the metal salt 22, the reaction or reactions of the metal salt 22, and the temperature of the reaction or reactions. In some examples, it may be desirable to perform a series of low energy pulses to bring the metal salt 22 to a temperature at which the metal salt 22 dehydrates, then another series of higher energy pulses to bring the dehydrated metal salt 22 to a temperature at which the dehydrated metal salt decomposes, then another series of even higher energy pulses to bring the decomposition products to a temperature at which the decomposition products are reduced to form the metal 22. In other examples, it may be desirable to perform a series of identical energy pulses to bring the metal salt 22 to a temperature that decomposes the metal salt 22 directly into the metal 22'.

In some examples of the methods 100, 200, 300, the metal build material 16 is heated to and maintained at each reaction temperature (e.g., dehydration temperature, decomposition temperature, reduction temperature, etc.) until the reaction is complete and before the metal build material 16 is heated to another reaction temperature. It may be desirable to heat and maintain the metal build material 16 at each reaction temperature until the reaction is complete to thermally decompose the metal salt 22 to metal 22'.

It is to be understood that diffusion mixing of the formed metal 22 'with the metal build material 16 occurs as soon as the metal 22' is formed. Thus, the sequence of light irradiation used to form the metal 22' may also induce diffusion mixing. Alternatively, the initial light irradiation may form a metal, and the light irradiation may be adjusted to induce diffusion mixing. Diffusion mixing occurs at any temperature and the mixing rate can be adjusted by adjusting the temperature. Thus, in some examples of methods 100, 200, 300, prior to applying additional build material 16, the method further includes adjusting the light illumination to induce diffusion mixing of metal 22 'with metal build material 16, adjusting the rate of diffusion mixing of metal 22' with metal build material 16, or a combination thereof. Diffusion mixing is slower at lower temperatures and faster at higher temperatures. Thus, if it is desired to accelerate the mixing of metal 22 'with metal build material 16, the energy of the light illumination may be increased to increase the temperature of metal 22' and metal build material 16. In addition, if it is desired to achieve more uniform mixing of the metal 22 'with the metal build material 16, the light illumination energy may be applied in multiple pulses/flashes to extend the time at which the metal 22' and metal build material 16 are at the temperature required for diffusion mixing. As one example, the flash/pulse number may be about 1 pulse to about 1000 pulses.

It is to be understood that during exposure of patterned build material layer 28 to light illumination, metallic build material 16 is kept below the sintering point of metallic build material 16. Thus, the metal build material 16 does not sinter early while the metal 22' binder is being formed. Thus, one or more of the reaction temperatures involved in forming the metal 22 'from the metal salt 22 and the temperature used to diffusion mix the metal 22' with the metal build material 16 may be below the sintering point of the metal build material 16.

The reaction temperature (e.g., dehydration temperature, thermal decomposition temperature, reduction temperature, etc.) and the temperature for diffusion mixing may depend in part on the metal salt 22 used and/or the metal build material 16 used. In one example, the dehydration temperature is from about 50 ℃ to about 200 ℃. In another example, the decomposition temperature is about 100 ℃ to about 350 ℃. In yet another example, the reduction temperature is from about 200 ℃ to about 700 ℃. In yet another example, when the metal build material 16 is stainless steel, the temperature for achieving a faster rate of diffusion mixing is about 300 ℃ to about 700 ℃. In this example, temperatures above 700 ℃ may cause the unpatterned metal build material 16 to sinter.

The pulse energy, frequency, and/or number in a particular light irradiation sequence may be controlled to achieve and maintain one or more reaction temperatures for a particular metal salt 22'. The parameters used may depend in part on the type of source 26, 26' used. For example, with a xenon flash lamp, higher pulse energies may allow higher temperatures to be reached. For another example, with another source 26, 26', repeated pulses at a high frequency may also allow higher temperatures to be reached. For yet another example, with a xenon flash lamp, many pulses (e.g., about 10 pulses to about 20 pulses) at a low frequency (e.g., 0.1Hz) may be used to reach temperature and maintain a desired duration, such as the time required for a particular reaction to occur. The temperature may decrease between pulses, so the timing of the pulses may be controlled to maintain the desired temperature.

The light irradiation may be applied with a light irradiation source 26 as shown in fig. 3C or with a light irradiation source 26' as shown in fig. 6. In one example of the methods 100, 200, 300, exposure of the metal build material 16 to light illumination is achieved with a xenon flash lamp. This particular example of the source 26, 26' results in a rapid temperature rise and a high reaction rate. Light illumination sources 26, 26' are discussed further below with reference to printing system 10 shown in fig. 6.

In some examples of the methods 100, 200, 300, the exposure of the metallic build material 16 to light radiation is achieved in an environment containing an inert gas, a reducing gas, or a combination thereof. Exposure of the metal build material 16 to light radiation may be achieved in an environment containing an inert gas and/or a reducing gas such that the metal salt 22, metal oxide, and/or metal 22 'undergo the desired reaction (e.g., dehydration, thermal decomposition, reduction, etc.) rather than undergoing an alternative reaction that does not produce metal 22' that binds the metal build material particles 16. Examples of inert gases include argon, helium, and the like. In some cases, nitrogen may also be a suitable inert gas. Examples of the reducing gas include synthesis gas, hydrogen gas, carbon monoxide gas, and the like.

In one example, the metal salt 22 is selected from copper nitrate (Cu (NO)₃)₂) Copper formate (C)₂H₂CuO₄) Copper sulfate (CuSO)₄) Copper oxalate (CuC)₂O₄) Nickel nitrate (Ni (NO))₃)₂) Nickel formate (C)₂H₂NiO₄) Nickel sulfate (NiSO)₄) Nickel oxalate (NiC)₂O₄) Nickel acetate (Ni (C)₂H₃O₂)₂) Nickel thiocyanate (Ni (SCN)₂) Iron nitrate (Fe (NO)₃)₂) Iron sulfate (FeSO)₄) Iron oxalate (FeC)₂O₄) Fe (C) iron acetate₂H₃O₂)₂Manganese nitrate (Mn (NO)₃)₂) Manganese formate (C)₂H₂MnO₄) Manganese oxalate (MnC)₂O₄) Cobalt nitrate (Co (NO)₃)₂) Cobalt formate (C) ₂H₂CoO₄) Cobalt sulfate (CoSO)₄) Cobalt oxalate (CoC)₂O₄) Cobalt thiocyanate (Co (SCN)₂) Chromium nitrate (Cr (NO)₃)₃) Chromium sulfate (CrSO)₄) Magnesium acetate (Mg (CH)₃COO)₂) Magnesium sulfate (MgSO)₄) Neodymium nitrate (Nd (NO)₃)₃) Vanadium Sulfate (VSO)₄) Vanadyl sulfate (VOSO)₄) Zirconium nitrate (Zr (NO)₃)₄) Zinc nitrate (Zn (NO)₃)₂) Zinc sulfate (ZnSO)₄) Silver nitrate (Ag (NO)₃)₂) Yttrium nitrate (Y (NO)₃)₃) And combinations thereof, and effecting exposure of the metallic build material 16 to light radiation in an environment containing an inert gas. In another example, exposure of the metal build material 16 to light radiation may be achieved using any of the above listed metal salts 22 in an environment containing a reducing gas.

The process illustrated in fig. 1, reference numerals 202 through 206 in fig. 2, and fig. 3A through 3C may be repeated to iteratively build several intermediate component layers to form the intermediate component 40. Fig. 2 shows, at reference numeral 208, that method 200 includes repeating the application of metal build material 16, the selective application of patterning fluid 20, and the exposure of metal build material 16 to light illumination. After the metal 22' is formed to adhere to one or more predetermined portions 30 of the layer 28 of build material, the controller 50 may process the data and, in response, cause the build area platform 12 to move a relatively small distance in a downward direction as indicated by double-headed arrow 34. In other words, build area platform 12 may be lowered to enable application of the next layer of metal build material 16. For example, build area platform 12 may be lowered a distance equal to the height of build material layer 28. In addition, after the build area platform 12 is lowered, the controller 50 may control the build material supply 14 to supply additional build material 16 (e.g., by operation of an elevator, screw conveyor, etc.) and control the build material distributor 18 to form another layer of build material with the additional build material 16 above the previously formed intermediate part layer. The newly formed layer of build material can be patterned with patterning fluid 20 and then exposed to light from light illumination sources 26, 26' to form another intermediate member layer.

As shown in fig. 3D, repeated formation, patterning, and exposure of new layers results in the formation of a build material cake 44 that includes the intermediate component 40 residing within the unpatterned portion 32 of each build material layer. The intermediate component 40 is a volume of the build material cake 44 filled with metal build material particles 16 bound by metal 22'. The remainder of the build material cake 44 is made up of unbonded metal build material particles 16.

In some examples of the methods 100, 200, 300, the intermediate component layer may be exposed to additional light irradiation after the metal 22' has been formed and before another layer is built up. In these examples, patterned build material 16 bonded by metal 22' is exposed to additional light irradiation sufficient to sinter at least the metal build material 16 in the portion 30. Because metal 22' may enhance light absorption within portions 30 and/or may enhance solid state diffusion between patterned metal build material 16, additional light irradiation may sinter build material 16 in patterned portions 30 while unpatterned build material 16 in unpatterned portions 32 remains unsintered. In these examples of methods 100, 200, 300, the repeating includes repeating the applying of metal build material 16, the selective applying of patterning fluid 20, and the exposing of metal build material 16 to the light illumination and the additional light illumination. This method forms a final component layer comprising sintered build material particles having metal 22' intermixed therein.

As shown in fig. 3D, the repeated formation, patterning, and exposure to the light irradiation and additional light irradiation results in the formation of a build material cake 44 that includes the final part 42 residing within the unpatterned portion 32 of each build material layer. The final part 42 is a volume of build material cake 44 that is a continuum of sintered metal build material particles intermixed with the metal 22'. The remainder of the build material cake 44 is made up of unbonded metal build material particles 16.

In any of the examples disclosed herein, the unpatterned portion 32 of each layer of build material can have a fining agent (fining agent) applied thereon prior to any light irradiation. It may be desirable to selectively deposit a refiner on one or more portions 32 to reduce unpatterned portionsLight absorption by the build material 16 in the segment 32. This helps prevent sintering of the build material particles 16 in one or more portions 32. An example of a refiner may be one that comprises a reflective material, such as titanium dioxide (TiO)₂) Water or solvent based ink jettable formulations of nanoparticles.

As shown in fig. 3E, the process 100, 200, 300 can continue by removing the intermediate component 40 or the final component 42 from the construction material cake 44. The components 40, 42 may be removed by any suitable means. In one example, the parts 40, 42 may be removed by lifting the parts 40, 42 from the unpatterned metallic build material particles 16. A removal tool may be used. In another example, the components 40, 42 may be removed using a wet or dry removal process. In the example shown in fig. 3E, the parts 40, 42 are removed using a wet removal process. In one example, the wet extraction process can include spraying the construction material cake 44 with water using one or more wet extraction tools 46, such as hoses and sprayers, spray guns, and the like. In other examples, the wet take-off process can include sonicating the cake of construction material 44 in a water bath or soaking the cake of construction material 44 in water. In some examples, instead of wet extraction, unpatterned metal particles 16 may be dry extracted from the build material cake 44. As one example, unpatterned metal particles 16 may be removed from the cake of build material 44 by suction from a vacuum hose and collected in a reservoir for future use. Metal build material particles 16 from unpatterned areas (e.g., 32 in fig. 3B) that remain bonded to intermediate part 40 or final part 42 can be removed by gentle grit blasting or cleaning with a brush and/or air jet.

After the final part 42 is removed from the cake of build material 44 and/or cleaned, the final part 42 may be used for its intended or desired use without any further processing.

After the intermediate component 40 is removed from the build material cake 44 and/or cleaned, the intermediate component 40 can be heated to a sintering temperature to sinter the metallic build material particles 16 and form the final component 42. Heating to the sintering temperature as indicated by arrow 48 to form the final part 42 is shown in fig. 3F.

The heat sintering is achieved at a sintering temperature sufficient to sinter the remaining metal build material particles 16. The sintering temperature is highly dependent on the composition of the metallic build material 16. During the heating/sintering process, intermediate component 40 may be heated to a sintering temperature that is about 80% to about 99.9% of the melting or solidus temperature, eutectic temperature, or transfusing temperature of metallic build material 16. In another example, intermediate component 40 may be heated to a sintering temperature that is about 90% to about 95% of the melting or solidus temperature, eutectic temperature, or transfusing temperature of metallic build material 16. In yet another example, intermediate component 40 may be heated to a sintering temperature that is about 60% to about 90% of the melting or solidus temperature, eutectic temperature, or transfuse temperature of metallic build material 16. In yet another example, the sintering temperature may be about 10 ℃ below the melting temperature (e.g., solidus temperature) of the metal build material 16 to about 50 ℃ below the melting temperature of the metal build material 16. In yet another example, the sintering temperature may be about 100 ℃ below the melting temperature (e.g., solidus temperature) of the metal build material 16 to about 200 ℃ below the melting temperature of the metal build material 16.

The sintering temperature may also depend on the particle size and sintering time (i.e., high temperature exposure time). As one example, the sintering temperature may be about 450 ℃ to about 1800 ℃. In another example, the sintering temperature is at least 900 ℃. One example of a sintering temperature for bronze is about 850 ℃, one example of a sintering temperature for stainless steel is about 1000 ℃ to about 1450 ℃, and one example of a sintering temperature for aluminum alloy is about 450 ℃ to about 600 ℃. While these temperatures are provided as examples of sintering temperatures, it is understood that the sintering temperature depends on the metal build material particles 16 used and may be higher or lower than the examples provided.

Heating at a suitable temperature sinters the metallic build material particles 16 to form a final part 42, which is densified relative to the intermediate part 40. For example, due to sintering, the density may vary from 50% density to over 90%, in some cases very close to 100% of theoretical density.

The length of time that heat is applied (for sintering) and the rate at which the intermediate member 40 is heated may depend on, for example, one or more of the following: characteristics of the heat source, characteristics of the metallic build material 16 (e.g., type, grain size, etc.), and/or characteristics of the components 40, 42 (e.g., wall thickness). In one example, the intermediate member 40 may be heated at the sintering temperature for a sintering time of about 1 hour to about 24 hours. The intermediate member 40 can be heated to the sintering temperature at a rate of about 1 c/min to about 20 c/min. It may be desirable to increase the rate of temperature up to the sintering temperature to produce a more favorable grain structure or microstructure. However, in some cases, a slower ramp rate may be desirable.

In some examples of the methods 100, 200, 300, the heating of the intermediate part 40 to form the final part 42 is accomplished in an environment containing an inert gas, a reducing gas, or a combination thereof. Sintering may be accomplished in an environment containing an inert gas and/or a reducing gas to sinter the metal build material particles 16 rather than undergoing an alternative reaction (e.g., an oxidation reaction) that fails to produce the final part 42, and/or to completely reduce any remaining metal salt 22 or decomposition products thereof to metal 22'.

In one example of the method 100, 200, 300, heating of the intermediate part 40 to form the final part 42 is achieved over a period of about 1 hour to about 24 hours and in an environment containing an inert or reducing gas.

As shown in fig. 5, one example of a three-dimensional (3D) printing method 400 includes: applying a metallic build material 16 (reference numeral 402); selectively applying a patterning fluid 20 over at least a portion 30 of a metal build material 16, the patterning fluid 20 comprising a metal salt 22 (reference numeral 404); a series of light irradiation sequences were performed as follows: exposing the metal build material 16 to a first light illumination to cause the metal salt 22 to reach a thermal decomposition temperature and thermally decompose to a metal oxide; exposing the metal build material 16 to a second sequence of light exposures to bring the metal oxide to a reduction temperature and to metal 22'; and exposing the metal build material 16 to a third light irradiation sequence to adjust a rate of diffusion mixing of the metal 22 'with the metal build material 16, wherein the metal 22' bonds the metal build material 16 in at least the portion 30 to form an intermediate part layer (reference numeral 406), and wherein during the series of light irradiation sequences, the metal build material 16 is maintained below a sintering temperature of the metal build material 16; then, repeating the application of the metallic build material 16, the selective application of the patterning fluid 20, and the sequence of light irradiations to form the intermediate member 40 (reference numeral 408); subjecting intermediate component 40 to a take-out process to separate intermediate component 40 from any unpatterned metallic build material 16 (reference numeral 410); and heating the intermediate component 40 to a sintering temperature to form a final component 42 (reference numeral 412).

Referring now to fig. 6, one example of a 3D printing system 10 is schematically depicted. It is to be understood that the 3D printing system 10 may include additional components (some of which are described herein) and may remove and/or modify some of the components described herein. Furthermore, the components of the 3D printing system 10 depicted in fig. 6 may not be drawn to scale, and thus, the 3D printing system 10 may have different sizes and/or configurations than shown therein.

In one example, a three-dimensional (3D) printing system 10 includes: a supply 14 of metallic build material 16; a build material distributor 18; a supply of a patterning fluid 20 comprising a metal salt 22; an applicator 24 for selectively dispensing the patterning fluid 20; light illumination sources 26, 26'; a controller 50; and a non-transitory computer readable medium having stored thereon computer executable instructions to cause the controller 50 to: dispensing a metallic build material 16 with a build material distributor 18; selectively dispensing a patterning fluid 20 on at least a portion 30 of the metallic build material 16 with an applicator 24; and exposing the metal build material 16 to light radiation using a light radiation source 26, 26 'prior to applying additional build material 16 to cause the metal salt 22 to reach a thermal decomposition temperature and thermally decompose to metal 22', wherein during the exposing, the metal build material 16 is maintained below its sintering temperature.

As shown in fig. 6, printing system 10 includes a build area platform 12, a build material supply 14 containing a metallic build material 16, and a build material distributor 18.

As mentioned above, build area platform 12 receives metallic build material 16 from build material supply 14. Build area platform 12 may be integral with printing system 10 or may be a component that is separately insertable into printing system 10. For example, build area platform 12 may be a module that is available independently of printing system 10. The illustrated build area platform 12 is an example and may be replaced by another support member, such as a platen, a manufacturing/printing bed, a glass plate, or another build surface.

As also mentioned above, the build material supply 14 may be a vessel, bed, or other surface that places the metallic build material 16 between the build material distributor 18 and the build area platform 12. In some examples, build material supply 14 may include a surface onto which metallic build material particles 16 are supplied, for example, from a build material source (not shown) located above build material supply 14. Examples of sources of build material may include hoppers, screw conveyors, and the like. Additionally or alternatively, the build material supply 14 may include a mechanism (e.g., a delivery piston) to provide (e.g., move) the metal build material 16 from a storage location to a location to be spread onto the build area platform 12 or onto a previously formed layer of the intermediate part 40 or the final part 42.

As also mentioned above, build material distributor 18 may be a blade (e.g., a doctor blade), a roller, a combination of a roller and a blade, and/or any other device (e.g., counter-rotating rollers) capable of spreading metal build material 16 over build area platform 12.

In some examples, the build material supply 14 or a portion of the build material supply 14 may move with the build material distributor 18 to continuously deliver build material 16 to the material distributor 18 rather than being supplied from a single location to the side of the printing system 10 as shown in fig. 6.

As shown in fig. 6, printing system 10 also includes an applicator 24, which may contain patterning fluid 20. The applicator 24 may scan across the build area platform 12 in the direction indicated by arrow 28, for example, along the y-axis. The applicator 24 may be, for example, a thermal inkjet printhead, a piezoelectric printhead, a continuous inkjet printhead, or the like, and may extend the width of the build area platform 12. Although the applicator 24 is shown in fig. 6 as a single applicator, it is to be understood that the applicator 24 may include multiple applicators spanning the width of the build area platform 12. In addition, the applicator 24 may be disposed in a plurality of print bars. The applicator 24 may also be scanned along the x-axis, for example in a configuration where the applicator 24 does not span the width of the build area platform 12, to enable the applicator 24 to deposit the patterning fluid 20 over a large area of the layer 28 of build material. The applicator 24 may thus be attached to a movable XY table or translation carriage 54 that moves the applicator 24 in close proximity to the build area platform 12 to deposit the patterning fluid 20 in the predetermined area 30 of the layer of build material 28 that has been formed on the build area platform 12 according to the methods 100, 200, 300, 400 disclosed herein. The applicator 24 may include a plurality of nozzles (not shown) through which the patterning fluid 20 is ejected.

The applicator 24 may deliver droplets of the patterned fluid 20 at a resolution of about 300 Dots Per Inch (DPI) to about 1200 DPI. In other examples, the applicator 24 may deliver droplets of the patterned fluid 20 with greater or lesser resolution. The drop velocity can be about 5m/s to about 24m/s and the jetting frequency can be about 1kHz to about 100 kHz. In one example, the volume of each droplet can be about 3 picoliters (pl) to about 18pl, although it is contemplated that higher or lower droplet volumes can be used. For example, the droplet volume can be about 10pl to about 40 pl. In some examples, the applicator 24 is capable of delivering variable drop volumes of the patterned fluid 20. One example of a suitable printhead has a 600DPI resolution and can deliver drop volumes of about 6pl to about 14 pl.

Each of the above-described physical elements is operatively connected to a controller 50 of the printing system 10. The controller 50 may process print data based on a 3D object model of the 3D object/part to be generated. In response to the data processing, the controller 50 may control the operation of the build area platform 12, the build material supplier 14, the build material distributor 18, and the applicator 24. As one example, the controller 50 may control actuators (not shown) to control various operations of the 3D printing system 10 components. Controller 50 may be a computing device, a semiconductor-based microprocessor, a Central Processing Unit (CPU), an Application Specific Integrated Circuit (ASIC), and/or another hardware device. Although not shown, the controller 50 may be connected to the 3D printing system 10 components via communication lines.

The controller 50 manipulates and transforms data that may be presented as physical (electronic) quantities within the printer's registers and memories in order to control the physical elements to create the 3D part. Thus, the controller 50 is depicted as being in communication with the data store 52. The data store 52 may include data regarding 3D parts to be printed by the 3D printing system 10. The data for selectively transporting the metal build material 16, the patterning fluid 20, etc., may be derived from a model of the 3D part to be formed. For example, the data may include the locations where the applicator 24 deposited the patterning fluid 20 on each layer of build material. In one example, the controller 50 may selectively apply the patterned fluid 20 using the data control applicator 24. Data storage 52 may also include machine readable instructions (stored on a non-transitory computer readable medium) that cause controller 50 to control the amount of metallic build material 16 supplied by build material supply 14, movement of build area platform 12, movement of build material distributor 18, movement of applicator 24, and the like.

As shown in fig. 6, printing system 10 may also include light illumination sources 26, 26'. In some examples, the light illumination source 26' may be in a fixed position relative to the build area platform 12. In other examples, light irradiation source 26 may be positioned to apply light irradiation to build material layer 28 immediately after patterned fluid 20 is applied to build material layer 28. In the example shown in fig. 6, the light irradiation source 26 is attached to the side of the applicator 24, which allows patterning and exposure to light irradiation to be achieved in a single pass.

The light illumination sources 26, 26' may emit pulses/flashes of light illumination. In one example, each pulse/flash may emit light having about 0.5J/cm²To about 50J/cm²And each pulse/flash may be greater than 0 (e.g., 10 mus) to about 50ms in length. In some examples, the length of each pulse/flash may be greater than 0ms to about 10 ms. Examples of light illumination sources 26, 26' may include gas discharge lamps, arc lamps, laser arrays, and/or arrays of high power light emitting diodes capable of producing high energy light pulses. In one particular example, the light irradiation sources 26, 26' may be xenon discharge lamps, rare gas flash lamps, mercury vapor lamps, metal halide lamps, or sodium vapor lamps. In another embodiment, the light irradiation source 26, 26' is a xenon strobe lamp (e.g., industrial grade xenon strobe lamp)。

The light illumination sources 26, 26' are operatively connected to a source driver, an input/output temperature controller, and a temperature and/or energy sensor, which are collectively shown as a light illumination system assembly 56. The light illumination system components 56 may operate together to control the light illumination sources 26, 26'. The temperature protocol (e.g., radiation exposure rate) may be communicated to an input/output temperature controller, and may depend on the chemical reaction or reactions of the metal salt 22 used. The temperature protocol may be preprogrammed and based on light intensity/temperature calibration data. During heating, the temperature sensor may sense the temperature of the metallic build material 16 and may communicate the temperature measurement to the input/output temperature controller. For example, a thermometer (e.g., a thermocouple) coupled to the heating zone may provide temperature feedback that may indicate the progress of the metal salt 22 in forming the metal 22'. For another example, a bolometer associated with the heating region may provide feedback on the incident radiation power and corresponding temperature changes, which may indicate the progress of the metal salt 22 in forming the metal 22'. The input/output temperature controller may adjust the power set point of the light illumination sources 26, 26' based on any difference between the recipe and the real-time measurements. These power set points are sent to the lamp/source driver, which delivers the appropriate voltage to the light irradiation sources 26, 26'. This is one example of a light illumination system assembly 56, and it is to be understood that other light illumination source control systems may be used. For example, the controller 50 may be configured to control the light illumination sources 26, 26'.

To further illustrate the disclosure, examples are given herein. It is understood that these examples are for illustration and are not to be construed as limiting the scope of the disclosure.

Examples