阅读说明：本技术 通过冷烧结制备陶瓷复合材料的方法 (Method for producing ceramic composite materials by cold sintering ) 是由 迈克尔·劳林 德文德拉·巴贾杰 乔纳森·博克 克里斯·韦尔兰德 于 2017-08-25 设计创作，主要内容包括：示出了陶瓷复合材料、装置和方法。在所选择的实例中,在低温下加工陶瓷材料,其允许掺入低温组分,如聚合物组分。制造方法包括但不限于注射成型、高压灭菌和压延。(Ceramic composites, devices and methods are shown. In selected examples, the ceramic material is processed at low temperatures, which allows for the incorporation of low temperature components, such as polymer components. Manufacturing methods include, but are not limited to, injection molding, autoclaving, and calendaring.)

1. A method of forming a sintered ceramic composite component comprising:

placing a quantity of powder comprising a cold sinterable ceramic powder into a mold;

placing a quantity of polymer or polymer precursor molecules into the mold;

applying an activating solvent for the powder in the mold;

heating to a first temperature and applying sufficient pressure to the powder, the quantity of polymer or polymer precursor molecules, and the solvent to activate sintering of the powder; and

heating to a second temperature to anneal the polymer phase of the sintered ceramic composite component.

2. The method of claim 1, wherein the second temperature is equal to or greater than a glass transition temperature of the amorphous polymer phase.

3. The method of claim 1, wherein the second temperature is equal to or greater than a melting temperature of a semi-crystalline polymer phase.

4. The method of claim 1, further comprising maintaining the sintered ceramic composite component under pressure while it is cooled to room temperature.

5. The method of claim 1, wherein the polymer phase comprises Polyetherimide (PEI).

6. The method of claim 5, wherein the cold sinterable ceramic powder comprises zinc oxide.

7. The method of claim 6, wherein applying sufficient pressure to the powder comprises: applying a pressure of less than or equal to 500 MPa.

8. The method of claim 7, wherein heating to the first temperature comprises: heating to a temperature above the boiling point of the activating solvent and not higher than 200 ℃.

9. The method of claim 8, wherein heating to the second temperature comprises: heating to a temperature between about 220 and 260 ℃.

10. The method of claim 6, wherein placing the quantity of polymer or polymer precursor molecules into the mold comprises: an amount of polymer or polymer precursor molecules is positioned to produce 20% -50% by volume fraction of polymer in the sintered ceramic composite component.

11. The method of claim 1, further comprising drying the amount of powder prior to sintering.

12. The method of claim 1, further comprising drying the sintered ceramic composite component after sintering.

13. The method of claim 1, wherein placing the quantity of powder comprising cold-sinterable ceramic powder into a mold comprises: the powder with an average diameter of less than 30 μm was placed.

14. The method of claim 1, wherein a plurality of components are stacked within a single mold and sufficient heat and pressure are applied to the plurality of components simultaneously.

Technical Field

The present invention relates to ceramic composites, applications and products made using ceramic composites, and to methods/manufacturing apparatus for ceramic composites. In one example, the present invention relates to a ceramic composite comprising at least one polymer integrated within a sintered microstructure.

Background

Sintering ceramic materials typically involves the use of a polymeric binder to hold ceramic powders together in a green state. The ceramic powder and the polymer binder are heated to a very high temperature, wherein the polymer binder is burned off, leaving only the ceramic material. At high temperatures, the particles of the ceramic powder begin to fuse together at the point of contact, forming only the sintered microstructure of the ceramic material.

Sintered ceramic composites are desirable due to the potential combination of material properties from the matrix and the dispersed phase. However, as with the burning off of the polymer binder in green body manufacture, the high temperature processing of ceramic powders in sintering makes many ceramic composites impossible. It is desirable to be able to form sintered ceramic structures at lower temperatures that allow for various composite material combinations, such as ceramic and polymer composites.

Drawings

Fig. 1A shows a mixture of powder particles prior to heating according to an embodiment of the invention.

FIG. 1B shows the material of FIG. 1A after an amount of heating in accordance with an embodiment of the present invention.

Fig. 2A shows a tool in one step of a manufacturing method according to an embodiment of the invention.

FIG. 2B shows the tool of FIG. 2A and workpiece material in another step of a method of manufacture according to an embodiment of the invention.

Fig. 2C shows the tool of fig. 2A and workpiece material in another step of a manufacturing method according to an embodiment of the invention.

FIG. 2D illustrates a composite ceramic object formed in accordance with an embodiment of the present invention.

Fig. 3 shows a portion of a manufacturing method according to an embodiment of the invention.

Fig. 4 shows a portion of a manufacturing method according to an embodiment of the invention.

Fig. 5 shows a method of forming a sintered ceramic component according to an embodiment of the present invention.

FIG. 6 illustrates a method of forming a sintered ceramic component according to an embodiment of the present invention.

FIG. 7 illustrates a method of forming a sintered ceramic component according to an embodiment of the present invention.

FIG. 8 illustrates a method of forming a sintered ceramic component according to an embodiment of the present invention.

Fig. 9A and 9B show a radial compression test setup and a transverse strain map according to an embodiment of the invention.

FIG. 10 shows a photomicrograph of a sample according to an embodiment of the invention.

FIG. 11 shows additional micrographs of samples according to embodiments of the present invention.

FIG. 12 shows a mold configuration according to an embodiment of the invention.

Fig. 13 shows a further micrograph of a sample according to an embodiment of the invention.

Detailed Description

In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In the drawings, like numerals describe substantially similar components throughout the several views. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention.

Values expressed in a range format should be interpreted in a flexible manner throughout the document to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of "about 0.1% to about 5%" or "about 0.1% to 5%" should be interpreted as including not only about 0.1% to about 5%, but also the various values (e.g., 1%, 2%, 3%, and 4%) and sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. Unless otherwise indicated, a statement of "about X to Y" has the same meaning as "about X to about Y". Likewise, unless otherwise specified, a statement of "about X, Y or about Z" has the same meaning as "about X, about Y, or about Z".

As used herein, the terms "a", "an" or "the" are intended to include one or more than one, unless the context clearly dictates otherwise. The term "or" is used to mean a non-exclusive "or" unless otherwise stated. The statement "at least one of a and B" has the same meaning as "A, B or a and B". Also, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. The use of any chapter title is intended to aid in reading the document and should not be construed as limiting; information related to the section header may appear inside or outside of that particular section.

In the methods described herein, acts may be performed in any order, except where time or sequence of operations is explicitly recited, without departing from the principles of the invention. Further, unless explicitly recited in a claim language as being performed separately, specified actions may be performed concurrently. For example, the claimed act of doing X and the claimed act of doing Y may be performed simultaneously in a single operation, and the resulting process would fall within the literal scope of the claimed process.

As used herein, the term "about" may allow for a degree of variability in the value or range, for example, within 10%, 5%, or 1% of the stated value or stated range limit, and includes the exact stated value or range. The term "substantially" as used herein means that the majority or majority is at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%.

As used herein, the term "polymer" refers to a molecule having at least one repeating unit, and may include copolymers.

The polymers described herein may be end-capped in any suitable manner. In some embodiments, the polymer may be end-capped with end groups independently selected from a suitable polymerization initiator, -H, -OH, substituted or unsubstituted (C) interrupted by 0, 1, 2 or 3 groups₁-C₂₀) Hydrocarbyl (e.g., (C)₁-C₁₀) Alkyl or (C)₆-C₂₀) Aryl) independently selected from-O-, substituted or unsubstituted-NH-and-S-, poly (substituted or unsubstituted (C)₁-C₂₀) Hydrocarbyloxy), and poly (substituted or unsubstituted (C)₁-C₂₀) Hydrocarbyl amino).

As used herein, the term "injection molding" refers to a process for preparing a molded part or form (form) by injecting a composition comprising one or more thermoplastic, thermoset, or combination thereof polymers into a mold cavity, wherein the composition cools and hardens to the structure of the cavity. Injection molding may include the use of heating via sources such as steam, induction, cartridge heaters, or laser treatment to heat the mold prior to injection, and the use of a cooling source such as water to cool the mold after injection, allowing for faster mold cycling and higher quality molded parts or profiles. An insert for an injection mold may form any suitable surface within the mold, such as a surface that contacts at least a portion of the injection molding material, such as a portion of an outer wall of the mold, or at least a portion of an interior of the mold around which the injection molding material is molded, for example. The insert for the injection mold may be an insert designed to be separated from the injection molding material at the end of the injection molding process. An insert for an injection mold may be an insert designed as part of an injection molded product (e.g., a heterogeneous injection molded product including an insert bonded to an injection molded material), where the injection molded product includes a junction between the injection molded material and the insert.

Fig. 1A shows a mixture 100 of powder particles prior to heating in accordance with an embodiment of the present invention. The mixture 100 includes a plurality of ceramic particles 102 in contact with each other at contact points 106. Many voids 104 are shown between the number of ceramic particles 102 due to interference between the particles 102 at the contact points 106. A number of secondary particles 110 are also shown as part of the mixture 100. After sintering, the amount of secondary particles 110 will remain within the microstructure of the final material and become a dispersed phase within the sintered ceramic matrix phase to form a sintered ceramic composite.

Although round powder particles are used as an example in the illustration of fig. 1A and 1B, the present invention is not limited thereto. Other shapes for the particles of the ceramic particles 102 and secondary particles 110 may include whiskers, rods, fibrils, fibers, flakes, and other physical forms that provide contact points with each other, as shown in fig. 1A.

In one example, the ceramic particles 102 comprise a binary ceramic, such as molybdenum oxide (MoO)₃). In other examples, the ceramic particles 102 may include binary, ternary, quaternary, etc. compounds consisting of families of oxides, fluorides, chlorides, iodides, carbonates, and phosphates. One example of a ternary ceramic particle includes K₂Mo₂O₇. Although these exemplary ceramic families serve as examples, this list is not exhaustive. As described in this disclosure can be anyCold sintered ceramics are within the scope of the invention.

Examples of choices of ceramic materials capable of cold sintering include, but are not limited to, BaTiO₃、Mo₂O₃、WO₃、V₂O₃、V₂O₅、ZnO、Bi₂O₃、CsBr、Li₂CO₃、CsSO₄、LiVO₃、Na₂Mo₂O₇、K₂Mo₂O₇、ZnMoO₄、Li₂MoO₄、Na₂WO₄、K₂WO₄、Gd₂(MoO₄)₃、Bi₂VO₄、AgVO₃、Na₂ZrO₃、LiFeP₂O₄、LiCoP₂O₄、KH₂PO₄、Ge(PO₄)₃、Al₂O₃、MgO、CaO、ZrO₂、ZnO-B₂O₃-SiO₂、PbO-B₂O₃-SiO₂、3ZnO_-2B₂O₃、SiO₂、27B₂O_3-35Bi₂O_3-6SiO_2-32ZnO、Bi₂₄Si₂O₄₀、BiVO₄、Mg₃(VO₄)₂、Ba₂V₂O₇、Sr₂V₂O₇、Ca₂V₂O₇、Mg₂V₂O₇、Zn₂V₂O₇、Ba₃TiV₄O₁₅、Ba₃ZrV₄O₁₅、NaCa₂Mg₂V₃O₁₂、LiMg₄V₃O₁₂、Ca₅Zn₄(VO₄)₆、LiMgVO₄、LiZnVO₄、BaV₂O₆、Ba₃V₄O₁₃、Na₂BiMg₂V₃O₁₂、CaV₂O₆、Li₂WO₄、LiBiW₂O₈、Li₂Mn₂W₃O₁₂、Li₂Zn₂W₃O₁₂、PbO-WO₃、Bi₂O_3-4MoO₃、Bi₂Mo₃O₁₂、Bi₂O-2.2MoO₃、Bi₂Mo₂O₉、Bi₂MoO₆、1.3Bi₂O_3-MoO₃、3Bi₂O_3-2MoO₃、7Bi₂O_3-MoO₃、Li₂Mo₄O₁₃、Li₃BiMo₃O₁₂、Li₈Bi₂Mo₇O₂₈、Li₂O-Bi₂O₃-MoO₃、Na₂MoO₄、Na₆MoO₁₁O₃₆、TiTe₃O₈、TiTeO₃、CaTe₂O₅、SeTe₂O₅、BaO-TeO₂、BaTeO₃、Ba₂TeO₅、BaTe₄O₉、Li₃AlB₂O₆、Bi₆B₁₀O₂₄、Bi₄B₂O₉. Although a separate ceramic material is listed, the disclosure is not so limited. In selected examples, the ceramic composition may include a combination of more than one ceramic material, including but not limited to the ceramic materials listed above.

In one example, the ceramic materials used in the cold sintering operations described in this disclosure may have a degree of piezoelectric behavior. In one example, the ceramic materials used in the cold sintering operations described in the present disclosure may have a degree of ferroelectric behavior. One example of such a material may include, but is not limited to, BaTiO₃As included in the non-limiting list of examples above.

In one example, the secondary particles 110 comprise polymer particles. In one example of a polymer particle, the polymer 110 can include a thermoplastic polymer, such as polypropylene. In one example of a polymer particle, the polymer 110 may comprise a thermoset polymer, such as an epoxy resin or the like. In one example of a polymer particle, the polymer 110 may comprise an amorphous polymer. In one example of a polymer particle, the polymer 110 can include a crystalline polymer. In one example of a polymer particle, the polymer 110 can include a semi-crystalline polymer. In one example of a polymer particle, the polymer 110 can include a blend, such as a miscible or immiscible blend polymer. In one example of a polymer particle, the polymer 110 can include a homopolymer. In one example of a polymer particle, the polymer 110 can include a copolymer, such as a random or block copolymer. In one example of a polymer particle, the polymer 110 can include a branched polymer. In one example of a polymer particle, the polymer 110 can include an ionic or nonionic polymer.

Some specific examples of acceptable polymers include, but are not limited to, polyethylene, polyester, Acrylonitrile Butadiene Styrene (ABS), Polycarbonate (PC), polyphenylene oxide (PPO), polybutylene terephthalate (PBT), isophthalic acid Isophthalate (ITR), nylon, HTN, polyphenylene sulfide (PPS), liquid crystal polymer (L CP), Polyaryletherketone (PAEK), Polyetheretherketone (PEEK), Polyetherimide (PEI), Polyimide (PI), fluoropolymer, PES, Polysulfone (PSU), PPSU, SRP (Paramax)^TM)、PAI(Torlon^TM) And blends thereof.

In one example, the mixture 100 may include one or more resins or oligomers that may be polymerized with other components of the mixture 100 in a mold (e.g., an injection mold) or other processed surface, in one example, the resins are flowable, an exemplary flowable resin may form a composition of the mixture 100 in any suitable proportion, such as about 50 wt% to about 100 wt%, about 60 wt% to about 95 wt%, or about 50 wt% or less, or less than, equal to, or greater than about 60 wt%, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.9, 99.99, or 99.999 wt% or more of a flowable resin may be included in a flowable resin, one or more curable resin such as a polybutadiene styrene (ABS) polymer, acrylic polymer, siro-polypropylene (PP), poly (PP-co-ethylene-propylene-co-ethylene-propylene-ethylene-co-propylene-ethylene-propylene-co-ethylene-propylene-co-ethylene-poly (PP-propylene-ethylene-propylene-co-ethylene-propylene-co-ethylene-propylene-co-ethylene-propylene-co-propylene-ethylene-co-poly-ethylene-propylene-ethylene-propylene-co-propylene-poly-ethylene-poly-propylene-co-ethylene-propylene-ethylene-poly-propylene-co-poly-ethylene-propylene-ethylene-poly-propylene-poly-ethylene-poly-co-ethylene-poly-propylene-poly-ethylene-propylene-poly-ethylene-propylene-ethylene-poly-ethylene-poly-co-poly-co-poly-.

In various embodiments, the flowable resin composition comprises a filler. The flowable resin may include one filler or more than one filler. The one or more fillers may form about 0.001 wt% to about 50 wt% of the flowable resin composition, or about 0.01 wt% to about 30 wt%, or about 0.001 wt% or less, or about 0.01 wt%, 0.1, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45 wt%, or about 50 wt% or more. The filler may be uniformly distributed in the flowable resin composition. The filler may be fibrous or particulate. The filler can be aluminum silicate (mullite), synthetic calcium silicate, zirconium silicate, fused silica, crystalline silica graphite, natural silica sand, etc.; boron powders such as boron nitride powder, boron silicate powder, and the like; oxides such as TiO₂Alumina, magnesia, and the like; calcium sulfate (in its anhydride, anhydrate or trihydrate form); calcium carbonates such as chalk, limestone, marble, synthetic precipitated calcium carbonate, and the like; talc, including fibrous, modular, acicular, lamellar talc, and the like; wollastonite; surface treated wollastonite; glass spheres such as hollow and solid glass spheres, silicate spheres, cenospheres, aluminosilicate (glass beads), and the like; kaolin, including hard kaolin, soft kaolin, calcined kaolin, kaolin comprising various coatings known in the art to facilitate compatibility with the polymeric matrix resin, and the like; single crystal fibers or "whiskers" such as silicon carbide, alumina, boron carbide, iron, nickel, copper, and the like; fibers (including continuous and chopped fibers) such as asbestos, carbon fibers, glass fibers; sulfides such as molybdenum sulfide, zinc sulfide, etc.; barium compounds such as barium titanate, barium ferrite, barium sulfate, barite, etc.; metals and metal oxides (e.g., particulate or fibrous aluminum, bronze, zinc, copper, and nickel, etc.); flaked fillers such as glass flakes, flaked silicon carbide, aluminum diboride, aluminum flakes, steel flakes, and the like; fibrous fillers, e.g. short inorganic fibres, e.g. derivativesThose derived from blends comprising at least one of aluminum silicates, aluminum oxides, magnesium oxides, and calcium sulfate hemihydrate or the like; natural fillers and reinforcements, such as wood flour obtained by pulverizing wood, fibrous products such as kenaf, cellulose, cotton, sisal, jute, flax, starch, corn flour, lignin, ramie, rattan, agave, bamboo, hemp, ground nut shells, corn, coconut (coconut shell), rice grain shells and the like; organic fillers such as polytetrafluoroethylene, reinforcing organic fibrous fillers formed from organic polymers capable of forming fibers such as poly (ether ketone), polyimide, polybenzoxazole, polyphenylene sulfide, polyesters, polyethylene, aromatic polyamides, aromatic polyimides, polyetherimides, polytetrafluoroethylene, acrylic resins, poly (vinyl alcohol), and the like; and fillers such as mica, clay, feldspar, flue dust, fillite, quartz, quartzite, perlite, diatomaceous earth, carbon black, or the like, or a combination comprising at least one of the foregoing fillers. The filler may be talc, kenaf or a combination thereof. The filler may be coated with a layer of metallic material to promote electrical conductivity, or the surface treated with silane, siloxane, or a combination of silane and siloxane to improve adhesion and dispersion with the flowable resin. The filler may be selected from carbon fibers, mineral fillers or combinations thereof. The filler may be selected from mica, talc, clay, wollastonite, zinc sulfide, zinc oxide, carbon fiber, glass fiber, ceramic coated graphite, titanium dioxide, or combinations thereof.

In one example, the secondary particles 110 may include one or more metals. Examples of metals that may be used include, but are not limited to, lithium, beryllium, sodium, magnesium, aluminum, potassium, calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, rubidium, strontium, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, cesium, barium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, mercury, thallium, lead, bismuth, polonium, francium, actinium, uranium, neptunium, plutonium, americium, curium, berkeley, californium, fernium, mercury, , mercury, indium, strontium, and iodine,, the temple, the root of Chinese silvergrass, , titanium, mold, .

In one example, the mixture 100 includes more than one type of secondary particle 110. For example, the secondary particles 110 may include both metal particles and polymer particles. In another example, the secondary particles 110 may include polymer particles and carbon particles, such as carbon black, graphite, carbon nanotubes, graphene, fullerenes, and the like. In another example, the secondary particles 110 may include polymer particles and modifying or reinforcing particles, such as glass fibers or other fibers.

Fig. 1A further shows activation solvent 108, which is at least partially present within the microstructure of mixture 100. In one example, the activation solvent 108 includes water. Various forms of water and/or water applications that may be introduced include liquid water, atomized or sprayed water, water vapor, and the like. In one example, the activating solvent 108 includes an alcohol. Other examples include mixtures of different liquids or gases to form the activation solvent 108. One of ordinary skill in the art having the benefit of this disclosure will recognize that the selection of the activation solvent 108 depends on the selection of the ceramic particles 102 and the selection of the secondary particles 110. An effective activating solvent 108 is capable of activating low temperature diffusion and/or material transport at the contact points 10 between the ceramic particles 102. The effective activation solvent 108 also does not adversely affect the material properties of the secondary particles 110. For example, the effective activation solvent 108 does not react with the secondary particles 110 in such a way that the secondary particles 110 volatilize below the sintering or activation temperature of the ceramic particles 102.

Fig. 1B shows the composite 101 formed after processing the mixture 100 from fig. 1A. The microstructure shown in fig. 1B shows a sintered or partially sintered microstructure. The material at the contact points 106 shown in fig. 1A has migrated to form the bonding regions 107, the bonding regions 107 connecting the sintered regions 103, the sintered regions 103 being originally separate ceramic particles 102 prior to sintering. In one example, the activation solvent 108 provides a mechanism to move material from the ceramic particles 102 to the bonding region 107 at a lower temperature than would be possible without the activation solvent 108. In one example, the activation solvent 108 lowers the temperature required for sintering to a temperature low enough that the secondary particles 110 comprising the polymer do not evaporate during sintering and will remain within the final microstructure, as shown in fig. 1B. Other materials than polymers requiring low sintering temperatures may also remain due to low temperature sintering.

After sintering, the microstructure of fig. 1B is a composite 101 that includes the sintered regions 103 and the bonded regions 107 as a substantially continuous matrix phase. At least some of the secondary particles 110 remain and form the dispersed phase 111 within the residual pores 105 of the composite 101. As described above, at least a portion of the secondary particles 110 (e.g., polymer particles) do not evaporate and remain within the microstructure as a result of low temperature sintering.

In the example shown in fig. 1B, the ceramic matrix phase includes a degree of closed porosity. In other words, after sintering, many of the residual porosity 105 is completely surrounded by the ceramic matrix phase and can no longer be accessed from outside the microstructure. Any remaining secondary particles 110, such as polymer particles, can only be present in the closed pores because they are located in the mixture 100 during sintering and remain present because the sintering temperature is lower than evaporation. It is not possible to introduce the dispersed phase material into the interior of the closed cell pores after sintering.

In one example, the polymeric secondary particles 110 are raised to a temperature during sintering that exceeds the glass transition temperature (T) of the polymer_g) But not exceeding the volatilization temperature of the polymer. In one example, the polymeric secondary particles 110 are raised to a temperature during sintering that exceeds the melting temperature (T) of the polymer_m) But not exceeding the volatilization temperature of the polymer. In addition to the ability to not exceed the volatilization temperature, in selected embodiments, the polymeric secondary particles 110 are raised to a temperature that does not exceed the decomposition temperature during sintering, wherein the desired molecular weight can be reduced.

It may be desirable for the polymeric secondary particles 110 to flow within the residual porosity 105 and fill the space during sintering. In this configuration, a larger contact area between the dispersed phase 111 and the surrounding ceramic matrix may be provided. The advantages of increased contact area may includeGood mechanical properties such as increased toughness, improved fracture strength, improved fracture strain and/or more desirable failure modes such as object cracking but not separation. In one example, the glass transition temperature (T) of the selected polymer is exceeded_g) Or melting temperature (T)_m) These features may be provided.

One of ordinary skill in the art having the benefit of this disclosure will recognize that sufficient activation temperature and pressure depend on many factors, such as the choice of ceramic material and the choice of activation solvent. One non-limiting example includes using water as the activation solvent and temperatures in excess of 100 ℃ to activate the system.

Fig. 1B shows at least some degree of closed cell porosity, and a dispersed phase 111, e.g., a polymeric dispersed phase, within at least some of the closed cells of the sintered microstructure. Since the dispersed phase 111 is mainly generated from the primary secondary particles 110, the material of the dispersed phase 111 is substantially similar or identical to that of the secondary particles 110 as described above.

In other examples, there may be no closed porosity, however, the cold-sintered microstructure is physically observable and distinguishable from conventional high temperature sintering. In one example, X-ray diffraction may be used to detect the crystal structure in the sintered region 103. High temperature sintering may result in a crystal structure change in the microstructure of the sintered region 103. These crystal changes are not present in the cold-sintered microstructure.

In another example, elemental analysis can be used to detect the presence or absence of compounds (e.g., hydroxides and carbonates). These compounds will burn off during high temperature sintering and are not found in the microstructure. In cold-sintered structures, compounds such as hydroxides and carbonates may still be present and detectable since the temperature during sintering does not reach a high enough point to burn off these compounds, indicating that the sintered microstructure was formed using cold sintering techniques.

In another example, the amount of densification may be measured. During high temperature sintering, the ceramic component may become more fully dense during cold sintering. Furthermore, grain growth in cold-sintered microstructures may be lower than in high-temperature sintering processes, with growth at the contact points in cold sintering increasing proportionally to growth in the individual grains themselves.

Fig. 2A-2D show one example of a method of manufacture and resulting product formed using the ceramic composite material described above. In fig. 2A, a first tool 202 and an engaging tool 206 are shown. In one example, first tool 202 and mating tool 206 are part of a mold. First tool 202 includes a first tool surface 204 and engaging tool 206 includes an engaging tool surface 208. In one example, one or more tool surfaces (204,208) are electrostatically charged.

In FIG. 2B, a quantity of powder (including cold sinterable ceramic powder as described in the embodiments above) is electrostatically charged, as opposed to a charge on one or more of the tool surfaces (204, 208). When a quantity of powder is introduced to one or more tool surfaces (204,208), a coating is formed due to electrostatic attraction between the opposing charges. A coating 214 is shown over the first tool surface 204 and a coating 218 is shown over the mating tool surface 208.

As described in the above embodiments, the amount of powder may include only cold sinterable ceramic powder. In other examples, the amount of powder may include secondary particles, such as polymers, carbon, metals, and the like, as described in the above embodiments. In one example, as described in the examples above, the charge on the amount of powder is retained in the polymeric secondary particles. The selected ceramic particles may not be able to retain sufficient charge on their own, and the addition of polymeric secondary particles may facilitate the coating process. In one example, other secondary particles besides polymer particles may facilitate the coating process. In one example, carbon particles such as graphite, carbon black, graphene, fullerenes, etc. may provide improved ability to retain charge and thus facilitate the coating process.

In one example, an amount of activating solvent is applied after coating one or more tool surfaces (204, 208). As noted above, in one example, the activation solvent comprises water. Various forms of water and/or water applications that may be introduced include liquid water, atomized or sprayed water, water vapor, and the like. In one example, the activating solvent comprises an alcohol. Other examples include mixtures of different liquids or gases to form the activated solvent.

In fig. 2C, first tool 202 and mating tool 206 are closed together to form interior space 220, interior space 220 being completely surrounded by coating 214 and coating 218. In one example, the interior space 220 is then filled with a polymer core 222. Sufficient heat and pressure are then applied to the coating (214,218) and the activation solvent to activate sintering of the powder in the coating (214, 218).

Since the sintering process uses an activation solvent as described above, sintering can be accomplished at a temperature lower than the evaporation temperature of the polymer core 222. As a result, FIG. 2D shows a composite object 230 that includes a substantially solid sintered ceramic shell formed from the now sintered and continuous coating (214,218), and a polymer core 222 within the sintered ceramic shell. Without the use of a low temperature sintering process as described above, the composite object 230 is not possible. During other high temperature sintering processes, the polymer core 222 may become volatile during sintering and may not remain within the interior space 220 after sintering.

One of ordinary skill in the art having the benefit of this disclosure will recognize that sufficient activation temperature and pressure depend on many factors, such as the choice of ceramic material and the choice of activation solvent. One non-limiting example includes using water as the activation solvent and temperatures in excess of 100 ℃ to activate the system. Non-limiting examples of injection molding pressures may be in the clamping pressure range of 0.5 tons to 7000 tons. Non-limiting examples of pressures in compression molding may be in the range of 10,000psi to 87,000psi of clamping pressure.

In one example, polymer resin, monomer, oligomer, or similar precursor polymer molecules may be introduced into a quantity of cold sinterable ceramic powder and subjected to heat and/or pressure within an injection molding mold, such as the tools shown in block diagram form in fig. 2A-2C. In one example, the precursor polymer molecules may polymerize and/or solidify while the cold-sinterable ceramic powder sinters. In one example, a quantity of partially cured polymer can be injected into an injection mold, for example, using a screw ram. In one example, the use of partially cured polymer better facilitates the use of a screw ram. For this method, the partially cured polymer may have sufficient mechanical structure in its partially cured state, in contrast to liquid monomers that may be difficult to place into an injection mold using a screw ram.

In one example, a first temperature and pressure may be used to activate the cold sintering process, while a second temperature and pressure may be used to activate the polymerization and/or curing of the polymer precursor molecules. In other examples, a single temperature and pressure may be used to activate polymerization and/or curing of the polymer precursor molecules and simultaneously activate the cold sintering process.

In one example, applying pressure can include compressing the flowable resin composition in the mold to any suitable pressure, such as about 1MPa to about 5,000MPa, about 20MPa to about 80MPa, or such as about 0.1MPa or less, or less than, equal to, or greater than 0.5MPa, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 90, 100, 125, 150, 175, 200, 250, 300, 400, 500, 750, 1,000, 1,500, 2,000, 3,000, 4,000, or about 5,000MPa or more. The method may include holding the mold cavity in a compressed state (using the flowable resin composition and the cold-sinterable ceramic powder) for a predetermined period of time, such as from about 0.1 second to about 10 hours, from about 1 second to about 5 hours, or from about 5 seconds to about 1 minute, or about 0.1 second or less, or about 0.5 seconds, 1 second, 2 seconds, 3 seconds, 4 seconds, 5 seconds, 10 seconds, 20 seconds, 30 seconds, 45 seconds, 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 3 hours, 4 hours, or about 5 hours or more.

Fig. 3 shows another example of a manufacturing method and resulting product formed using the ceramic composite material described above. A manufacturing system 300 is shown. In fig. 3, a quantity of powder 304 (including cold sinterable ceramic powder) is placed in contact with the first tool surface 302. As described in the above embodiments, the amount of powder 304 may include only cold sinterable ceramic powder. In other examples, the amount of powder 304 may include secondary particles, such as polymers, carbon, metals, and the like, as described in the above embodiments.

A quantity of activating solvent is applied to a quantity of powder 304. As noted above, in one example, the activation solvent comprises water. Various forms of water and/or water applications that may be introduced include liquid water, atomized or sprayed water, water vapor, and the like. In one example, the activating solvent 108 includes an alcohol. Other examples include mixtures of different liquids or gases to form the activated solvent.

In one example, the mating tool surface 306 is placed over the first tool surface 302 with the powder 304 between the first tool surface 302 and the mating tool surface 306. In one example, the first tool surface 302, the mating tool surface 306, and the powder 304 are placed in a vacuum bag 308 to form an assembly 312. In one example, the assembly 312 is then placed in an autoclave 310 and sufficient heat and pressure are applied to the powder and solvent to activate sintering of the powder 304.

In the example of fig. 3, the vacuum bag 308 facilitates the application of pressure, while the autoclave provides heat to activate the system. Although vacuum bagging is used as an example of pressure application, other methods and tools may be used, such as mechanical pressure between molds, and the like. Although an autoclave is used as an example of the method of applying heat, the present invention is not limited thereto. Other heat sources may be used without departing from the scope of the invention.

One advantage of using vacuum bagging techniques includes the ability to apply uniform pressure to tools and/or powder compacts having complex shapes. Although two flat plates are shown in fig. 3 as exemplary curved plates, vacuum bagging may be used to form non-planar configurations and complex shapes.

One of ordinary skill in the art having the benefit of this disclosure will recognize that sufficient activation temperature and pressure depend on many factors, such as the choice of ceramic material and the choice of activation solvent. One non-limiting example includes using water as the activation solvent and temperatures in excess of 100 ℃ to activate the system. Non-limiting examples of pressures in autoclaving can be up to 0.137 MPa. Non-limiting examples of durations in autoclaving can range from about 20 minutes to about 360 minutes.

Fig. 4 shows another example of a manufacturing method and resulting product formed using the ceramic composite material described above. A manufacturing system 400 is shown. In fig. 4, a quantity of powder 404 (including cold sinterable ceramic powder) is placed in contact with the first tool surface 402. As described in the embodiments above, the amount of powder 404 may include only cold sinterable ceramic powder. In other examples, the amount of powder 404 may include secondary particles, such as polymers, carbon, metals, and the like, as described in the above embodiments.

Fig. 4 shows that the first tool surface 402 and the amount of powder 404 together form a stack 405. An amount of activating solvent 412 is applied to the amount of powder 404. A block diagram of a dispenser 410 is shown, however any number of application devices may be used to introduce the activation solvent 412. As noted above, in one example, the activation solvent comprises water. Various forms of water and/or water applications that may be introduced include liquid water, atomized or sprayed water, water vapor, and the like. In one example, the activating solvent 108 includes an alcohol. Other examples include mixtures of different liquids or gases to form the activated solvent.

Figure 4 also shows the stack being run through one or more calendering rolls. In the example of fig. 4, a first calendering roll 406 and a second calendering roll 408 are shown. For ease of illustration, stack 405 is shown as substantially flat, and only two calendering rolls (406,408) are shown. Other configurations may include running the flexible stack 405 around at least a partial arc of calendering rolls and using additional calendering rolls as needed.

In one example, sufficient heat and pressure are applied to the stack 405 to activate sintering of the powder 404. Heated calender rolls may be used. In one example, rollers (e.g., 406,408) are pressed together to provide the necessary pressure to activate sintering of the powder 404.

One of ordinary skill in the art having the benefit of this disclosure will recognize that sufficient activation temperature and pressure depend on many factors, such as the choice of ceramic material and the choice of activation solvent. One non-limiting example includes using water as the activation solvent and temperatures in excess of 100 ℃ to activate the system. Non-limiting examples of calendering pressures can range from about 100 to about 1000 pounds per linear inch.

In one example, applying the amount of powder 404 to the first tool surface 402 may be accomplished using an electrostatic method as described above with respect to fig. 2A-2D. As described above, in selected embodiments, it may be advantageous to use secondary particles added to the powder 404 to improve charge retention in electrostatic instances. In one example, the polymer particles may facilitate the coating process by maintaining an electrical charge. In one example, carbon particles such as graphite, carbon black, graphene, fullerenes, etc. may provide improved ability to retain charge and thus facilitate the coating process.

In one example, the Coefficient of Thermal Expansion (CTE) of a composite material as described in the present disclosure may be varied by selecting respective amounts of the cold-sintered ceramic component and the polymeric second phase component. The modification of the CTE in the composite material may facilitate the matching of the CTE to adjacent components to prevent stress cracking or other failure that may result from CTE mismatch in adjacent components.

Selected example composite dielectric materials were tested to determine their CTE. In one example, the CTE of the cold-sintered mixed material was measured using a TA instruments thermomechanical analyzer TMA Q400 and the data was analyzed using a TA instruments Universal analysisv4.5 a.

The sample was reshaped to form a circular diameter of 13mm, 2mm thick pellet to fit a TMAQ400 apparatus. Once placed in TMA Q400, the sample was heated to 150 ℃ (@20 ℃/min) at which time moisture and stress were relieved, and then cooled to-80 ℃ (@20 ℃/min) to begin the actual coefficient of thermal expansion measurement. The samples were heated from-80 ℃ to 150 ℃ at a temperature of 5 ℃ per minute, at which temperature the shift with temperature was measured.

The measurement data is then loaded into analytical software and the coefficient of thermal expansion is calculated using the α x1-x2 method, which measures the dimensional change from temperature T1 to temperature T2 and converts the dimensional change to a coefficient of thermal expansion value by the following equation:

wherein:

Δ L ═ length change (μm)

Δ T-temperature Change (. degree. C.)

L0 sample length (m)

Three polymers were tested for coefficient of thermal expansion at different levels using TMA Q400, including Polyetherimide (PEI), Polystyrene (PS), and polyester, each at L iMn₂O₄(L MO) in the cold-sintered sample the results can be seen in Table 1 below.

TABLE 1 thermal expansion coefficients of L MO/PEI, L MO/PS and L MO/polyester cold-sintered composites

Fig. 5 shows an example of a flow chart of a manufacturing method according to an embodiment of the invention. In operation 502, a tool surface is charged with a first charge. In operation 504, a powder comprising a cold-sinterable ceramic powder is charged with a second charge opposite the first charge. In operation 506, a quantity of powder is placed in contact with the tool surface and the powder remains on the tool surface due to the first and second charges. In operation 508, an activating solvent is applied to the powder. Finally, in operation 510, sufficient heat and pressure are applied to the powder and solvent to activate sintering of the powder.

Fig. 6 shows another example of a flow chart of a manufacturing method according to an embodiment of the present invention. In operation 602, a quantity of powder (including a cold sinterable ceramic powder) is placed in contact with a first tool surface. In operation 604, an activating solvent is applied to the powder. In operation 606, a mating tool surface is placed over the first tool surface with the powder between the first tool surface and the mating tool surface. In operation 608, the first tool surface, the mating tool surface, and the powder are placed in a vacuum bag to form an assembly. Finally, in operation 610, the assembly is placed in an autoclave and sufficient heat and pressure are applied to the powder and solvent to activate sintering of the powder.

Fig. 7 shows another example of a flow chart of a manufacturing method according to an embodiment of the present invention. In operation 702, a quantity of powder (including cold sinterable ceramic powder) is placed on a flat carrier surface to form a stack. In operation 704, an activating solvent is applied to the powder. In operation 706, the stack is run through one or more calendering rolls. In operation 708, sufficient heat and pressure are applied to the stack to activate sintering of the powder.

Fig. 8 shows another example of a flow chart of a manufacturing method according to an embodiment of the present invention. In operation 802, a quantity of powder (including a cold sinterable ceramic powder) is placed in an injection molding tool. In operation 804, a quantity of polymer or polymer precursor molecules is placed in an injection molding tool. In operation 806, an activating solvent for the powder is applied in the injection molding tool. In operation 808, sufficient heat and pressure are applied to the powder, the amount of polymer or polymer precursor molecules, and the solvent to activate sintering of the powder.

In selected embodiments, any of the cold sinterable ceramic powders described in this disclosure may be dried prior to processing. While a solvent such as water may be used in selected embodiments to facilitate cold sintering, additional processes of drying the cold sinterable ceramic powder prior to application of the solvent and pressure may improve mechanical properties including, but not limited to, fracture stress, fracture strain, fracture toughness, and the like.

In selected examples, any of the cold sinterable ceramic powders described in this disclosure may be annealed after cold sintering. In select examples, the annealing process may include a glass transition temperature (T) at or above the polymer composition after cold sintering_g) The cold sintered ceramic composite as described in the present disclosure is held at a given temperature for a given amount of time. In select examples, the annealing process may includeIncluding at or above the melting temperature (T) of the polymer component after cold sintering_m) The cold sintered ceramic composite as described in the present disclosure is held at a given temperature for a given amount of time. The glass transition temperature can generally be applied to amorphous polymers or amorphous components of polymers. The melting temperature may generally be applied to a crystalline or semi-crystalline polymer or a crystalline or semi-crystalline component of a polymer.

In selected embodiments, the annealing alters the microstructure of the cold-sintered ceramic composite to increase the interfacial surface area between the polymer and the ceramic. In selected embodiments, the annealing changes the microstructure of the cold-sintered ceramic composite to connect the polymer regions to the more adherent polymer phase within the cold-sintered ceramic composite. For example, the annealed polymer may flow by exceeding the glass transition temperature, or by partial or complete melting. A certain degree of flow in the polymer phase can positively affect the mechanical properties of the cold-sintered ceramic composite.

In order to demonstrate the selected processing techniques and resulting properties, a number of non-limiting examples are shown and described below, hi the present invention, L MO refers to L i₂MoO₄Although L MO is used as an example, the invention is not so limited and any ceramic capable of some degree of sintering as described above is within the scope of the invention.

Radial compression test

In the radial compression test method, a disk is compressed along its diameter by two flat metal plates. Compression along the diameter produces a maximum tensile stress perpendicular to the loading direction of the mid-plane of the specimen [ see reference JJ Swab et al, Int JFract (2011)172:187-]. Fracture Strength (σ) of ceramics_f) Can be calculated by the following formula:

where P is the breaking load, D is the disc diameter, and t is the disc thickness.

All testsElectroPlus with 5000N load cell at room temperature^TME3000 all electric dynamic tester (Instron). The test specimen was mounted between two flat metal plates and a small preload of 5N was applied. Radial compression testing was performed under displacement control (0.5mm/min) and time, compression displacement and load data were captured at 250 Hz.

During radial compression, successive images of the spotted surface were captured at a frequency of 50Hz using an INSTRON video extensometer AVE (Fujinon 35 mm.) subsequent testing, all images were analyzed using DIC replay software (Instron) to generate a full field strain map, the transverse strain (x) was analyzed in a region of 6mm × 3mm in the mid-plane of each sample and calculated: (X)_x). Calculating the strain at break at maximum load (_f)。

Fig. 9A and 9B show a radial compression test configuration. (9A) The sample loaded under radial compression. The arrows indicate the direction of the applied load. The surface of the sample was spotted with black paint. (9B) Full field transverse strain: (_x) Figure (a). The rectangular box in the midplane represents the area where the lateral strain is calculated.