阅读说明：本技术 同步喷射雾化沉积和致密化的零件制备方法 (Method for preparing parts by synchronous spray atomization deposition and densification ) 是由 陈业高 施允洋 胡昌军 葛海浪 陈国斌 于 2021-08-06 设计创作，主要内容包括：本发明涉及精密增材制造方法领域,公开了一种同步喷射雾化沉积和致密化的材料或零件制备方法,采取切片-喷射沉积-致密化-喷射沉积的循环工序,可直接成型结构复杂、精度较高的零件；喷射雾化沉积步骤能够细化晶粒,抑制元素偏析,使获得的沉积坯坯料晶粒细小,圆整,成分均匀,减小或消除应力集中；致密化消除沉积坯内的空隙,提高致密度,提高耐疲劳和力学性能；属于近净成型技术,减少或消除后续机械加工工序,提高效率。(The invention relates to the field of precise additive manufacturing methods, and discloses a method for preparing a material or a part by synchronous spray atomization deposition and densification, which adopts the cyclic procedures of slicing, spray deposition, densification and spray deposition and can directly form a part with a complex structure and higher precision; the step of spray atomization deposition can refine grains, inhibit element segregation, enable the obtained blank of the deposition blank to have fine, round and uniform grains and reduce or eliminate stress concentration; the densification eliminates the gap in the deposition blank, improves the density and improves the fatigue resistance and the mechanical property; belongs to the near net shaping technology, reduces or eliminates subsequent machining procedures and improves the efficiency.)

1. A method for preparing a material or a part through synchronous spray atomization deposition and densification is characterized by comprising the following steps:

s1: part model or material model slicing processing: slicing the part model or the material model along a certain direction by adopting a computer technology, wherein the thickness of each slice layer is h, and generating a contour track of a solid part of each slice layer;

s2: primary spray atomization deposition: controlling the movement track of a nozzle for spray atomization deposition, and performing spray atomization deposition on the molten metal meeting the component and temperature of the part according to the profile track corresponding to the solid part of the first sliced layer to ensure that the molten metal is atomized and deposited on the substrate to form a first deposited blank layer with the thickness of H = 1.05-1.1H and the profile of the first deposited blank layer is the same as that of the first sliced layer;

in the process of spray atomization deposition, the substrate temperature is controlled to be 0.2-0.6 Tm, the gas-liquid mass flow rate of atomization gas and metal liquid is 0.3-1.2, the spray distance is 10-300 mm, the atomization temperature (the temperature of a melt) is 1.05-1.3 Tm, wherein Tm is the melting point of the metal to be processed;

s3: primary densification treatment: carrying out densification treatment on the first deposition blank layer, wherein the thickness of the first deposition blank layer is equal to h after the densification treatment;

s4: and controlling the distance between the nozzle and the uppermost deposition blank layer on the substrate to be constant all the time, and sequentially and circularly operating according to the sequence of spray atomization deposition and densification treatment in the completely same manner in S2 and S3 until products with the same size and shape as the part model or the material model are obtained.

2. The method of claim 1, wherein the material model is a composite material consisting of a matrix material and a reinforcement material

In S1, the thicknesses of the front and rear slicing layers are h1 and h2, wherein h1= 0.3-0.95 h, h2= 0.05-0.5 h, and h1+ h2= h, respectively;

the molten metal sprayed in the step S2 is the molten metal of the base material, the formed first deposition blank layer is a first base material layer, and the thickness of the first base material layer is H1= 1.05-1.1H 1;

after S2 and before S3, the method further comprises the following steps:

spraying a reinforcing material on the first base material layer to form a first reinforcing material layer, wherein the thickness of the first reinforcing material layer is H2= 1.05-1.1H 2;

in S3, the first base material layer and the first reinforcing material layer are densified, and after the densification, the total thickness of the first base material layer and the first reinforcing material layer is equal to h.

3. The method for preparing parts through synchronous spray atomization deposition and densification according to claim 1, wherein in S2, if the molten metal is active and easily oxidized, the spray atomization deposition is performed in a closed chamber, 0.1-0.12 MPa of atomization gas is introduced before spraying for 5-15 min, then the closed chamber is evacuated and depressurized, and the spray atomization deposition is performed after the air pressure in the closed chamber is stabilized at 0.05-0.08 MPa.

4. The method of preparing a part by simultaneous spray atomization deposition and densification of claim 1, wherein in S3:

for small parts, after the first layer of deposition blank layer is formed, stopping spraying and atomizing the molten metal, and simultaneously continuously introducing atomizing gas and carrying out densification treatment on the first layer of deposition blank layer;

for large parts, densification treatment is carried out while spraying atomization deposition.

5. The method of preparing a part by simultaneous spray atomization deposition and densification of claim 1 further comprising, after S3 and before S4, the steps of:

trimming: and repairing the defects of burrs, fins, increased width and the like caused by the transverse flow of the metal after the densification treatment, and removing redundant materials.

6. The method for the production of a part according to any of claims 1 to 5 wherein h is 0.05-5 mm if the densification process is mechanical compaction.

7. The method of claim 6 wherein the punch temperature during the mechanical compaction process is 0.4-0.6 Tm, wherein Tm is the melting point of the metal being processed; the downward moving speed of the punch is 2-20 mm/s; the frequency of punch compaction is 50-200 times/min.

8. The method of claim 6 wherein the mechanical compaction is performed with a punch reduction of 5 to 15% of the total thickness of the deposited green layer during the two mechanical compaction intervals, measured from the contact of the end face of the punch with the uppermost deposited green layer.

9. The method for the production of a part according to any of claims 1 to 5 wherein the h is 0.05 to 0.3mm if the densification process is by laser pulse densification.

10. The method of claim 9 wherein the laser pulses are applied at a frequency of 10 during the laser pulse densification process⁵~10¹²HZ, pulse power is 0.5-3.5W, pulse width is 2.5-4.5 ms, pulse scanning speed is 2-20 mm/s, and pulse spot diameter is 2-10 mm.

Technical Field

The invention relates to the field of metal manufacturing, in particular to a part preparation method for synchronous spray atomization deposition and densification.

Background

The metal spray forming technology is a preparation technology of a fast solidification forming material, the method naturally combines atomization (fast solidification) of liquid metal and deposition (molten drop dynamic compact solidification) of atomized molten drops, and high-performance materials or near-net forming parts are directly prepared from the liquid metal by using the minimum procedures. Meanwhile, the method has the advantages of powder metallurgy technology, and is a rapid solidification process with high competitiveness. Due to the tissue advantage of rapid solidification, the properties of various spray atomization deposition materials, such as corrosion resistance, wear resistance, magnetism, strength, toughness and the like, are greatly improved compared with the materials produced by the conventional casting and forging process, and the properties of the materials can be equivalent to those of powder metallurgy materials.

For the industrial production of the metal injection molding technology, the sufficient processing efficiency needs to be ensured to meet the technological properties of different metal parts. However, the existing metal injection molding technology mainly uses raw materials for preparation, and it is difficult to directly prepare parts by the injection molding technology. Even for injection molding of parts having a simple structure, the compactness is often insufficient, and the injection molding cannot be applied to a particular application field. In addition, the current injection molding preparation of raw materials cannot be directly applied because the raw materials contain 1-10% of pores.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the problems in the prior art, the invention provides a part preparation method for synchronously spraying, atomizing, depositing and densifying, and the prepared part has the advantages of fine crystal grains, uniform components, higher compactness and excellent mechanical property.

The technical scheme is as follows: the invention provides a method for preparing a material or a part by synchronous spray atomization deposition and densification, which comprises the following steps: s1: part model or material model slicing processing: slicing the part model or the material model along a certain direction by adopting a computer technology, wherein the thickness of each slice layer is h, and generating a contour track of a solid part of each slice layer; s2: primary spray atomization deposition: controlling the movement track of a nozzle for spray atomization deposition, and performing spray atomization deposition on the molten metal meeting the component and temperature of the part according to the profile track corresponding to the solid part of the first sliced layer to ensure that the molten metal is atomized and deposited on the substrate to form a first deposited blank layer with the thickness of H = 1.05-1.1H and the profile of the first deposited blank layer is the same as that of the first sliced layer; in the process of spray atomization deposition, the temperature of a substrate is controlled to be 0.2-0.6 Tm, the gas-liquid mass flow rate of atomizing gas and metal liquid is 0.3-1.2, the spray distance is 10-300 mm, and the temperature of the atomizing gas is 1.05-1.3 Tm, wherein Tm is the melting point of the metal to be processed; s3: primary densification treatment: carrying out densification treatment on the first deposition blank layer, wherein the thickness of the first deposition blank layer is equal to h after the densification treatment; s4: and controlling the distance between the nozzle and the uppermost deposition blank layer on the substrate to be constant all the time, and sequentially and circularly operating according to the sequence of spray atomization deposition and densification treatment in the completely same manner in S2 and S3 until products with the same size and shape as the part model or the material model are obtained.

Preferably, if the material model is a composite material composed of a base material and a reinforcing material, in S1, the thicknesses of the front and rear sliced layers are h1 and h2 slices alternately, wherein h1= 0.3-0.95 h, h2= 0.05-0.5 h, and h1+ h2= h; the molten metal sprayed in the step S2 is the molten metal of the base material, the formed first deposition blank layer is a first base material layer, and the thickness of the first base material layer is H1= 1.05-1.1H 1; after S2 and before S3, the method further comprises the following steps: spraying a reinforcing material on the first base material layer to form a first reinforcing material layer, wherein the thickness of the first reinforcing material layer is H2= 1.05-1.1H 2; in S3, the first base material layer and the first reinforcing material layer are densified, and after the densification, the total thickness of the first base material layer and the first reinforcing material layer is equal to h. The layer-by-layer spray deposition of the base material and the reinforcing material has the following advantages compared with the simultaneous spray deposition of the base material and the reinforcing material: (1) the thickness of the deposition layers of the base material layer and the reinforcing material layer is controllable, and the base material layer and the reinforcing material layer are the basis of precise forming; (2) after the base material and the reinforcing material are compounded, the structure of each layer of the material is clear, and different properties of each layer of the material, such as electricity, heat, sound, magnetism and the like, are easily utilized; (3) the reinforcing material can be fibrous and is not limited to powder particles during simultaneous spray deposition; (4) the method can be directly used for forming parts, and meanwhile, the spray deposition can only be used for preparing materials; in the application, the selection of h1 and h2 directly influences the contact mixing between the matrix material and the reinforcing material, and the performance difference of the prepared composite material and the performance difference of the material model is ensured to be within an allowable range.

Preferably, in S2, if the molten metal is an active and easily oxidized molten metal, the spray atomization deposition is performed in the closed chamber, before the spray, 0.1 to 0.12MPa of atomization gas is introduced for 5 to 15min, then the closed chamber is evacuated and depressurized, so that the pressure in the closed chamber is stabilized at 0.05 to 0.08MPa, and then the spray atomization deposition is performed. The atomizing gas used in the application is any one or the combination of nitrogen, argon and methane; the atomizing gas is used for blowing the molten metal into small droplets, and generally, gases with inactive properties are selected, and nitrogen and argon are most commonly used; the existing research shows that if the heavy metal is contained, the atomization effect of the gas with large atomic weight is better; if the metal is light metal, the atomization effect is better when the atomic weight is small; if the metal is active, the gas is chosen with a view to protecting the metal from oxidation, and nitrogen and argon are satisfactory, but nitrogen is cheaper.

Preferably, in S3: for small parts, after the first layer of deposition blank layer is formed, stopping spraying and atomizing the molten metal, and simultaneously continuously introducing atomizing gas and carrying out densification treatment on the first layer of deposition blank layer; for large parts, densification treatment is carried out while spraying atomization deposition. Because the deposition surface of the small part is small in size, a deposition layer still has high temperature after a certain layer is completely deposited, and the densification treatment still belongs to thermal deformation of the material at the temperature; in order to bring the metal powder which is not deposited out of the sealing chamber and ensure that the pressure of the sealing chamber is unchanged, after the first layer of deposition blank layer is formed, when the spraying atomization of the metal liquid is stopped, the densification treatment is carried out while continuously introducing the atomization gas, so that the influence of the excessive metal powder on the precision of the deposition layer is prevented; the large part is large in deposition surface size and long in deposition time, the part deposited firstly can be cooled, if the large part is not immediately densified, the cold metal deformation resistance is large, metal flowing and forming are not facilitated, and gap filling and size precision control are not facilitated, so that for large part forming, a method of densification treatment while spray atomization deposition is adopted is required.

Preferably, after S3 and before S4, the method further comprises the following steps: trimming: and repairing the defects of burrs, fins, increased width and the like caused by the transverse flow of the metal after the densification treatment, and removing redundant materials. The trimming treatment is to ensure that the wall thickness of the prepared product meets the requirement and the surface is flat and smooth.

Further, if the densification treatment mode is mechanical compaction, the h is 0.05-5 mm. When the machine is compacted, the die section structure formed between the machine pressure head and the substrate can cut off excessive deposit materials outside the outline track formed in the compacting process, so that the prepared product has no flash and smooth surface.

Preferably, during the mechanical compaction process, the temperature of the punch is 0.4-0.6T, wherein Tm is the melting point of the metal to be processed; the downward moving speed of the punch is 2-20 mm/s; the frequency of punch compaction is 50-200 times/min. In the mechanical compaction process, the temperature of the punch is controlled to be 0.4-0.6 Tm, so that the metal liquid adhered to the punch can be reduced, and the compaction effect is improved; in addition, in practical application, a thin film can be plated on the surface of the punch, which is in contact with the deposition layer, the thin film is not wetted with the deposited metal, and the adhesion phenomenon between the punch and the deposition layer can be reduced.

Furthermore, in the mechanical compaction process, the pressing amount of the punch is 5-15% of the total deposition thickness of the deposited blank layer in the time interval of two times of mechanical compaction, and the pressing amount is calculated from the contact of the end face of the punch and the uppermost deposited blank layer. The design enables the thickness of the deposition blank after mechanical compaction and densification to reach the thickness of each slice layer, and ensures that the size of the part or material obtained by final preparation is the same as that of the part model or the material model.

Preferably, if the densification treatment is laser pulse compaction, the h is 0.05-0.3 mm. The laser pulse generates residual compressive stress, and the fatigue strength of the material is improved; in addition, after the pulse laser impact, high-density dislocation and phase change are left in the material, so that the hardness and the bending stress of the material are improved; in addition, a pulse laser cleaning and pollution-free treatment method; and because the pulse laser processing flexibility is strong, stress concentration parts such as round corners and corners can be processed.

Preferably, during laser pulse compaction, the frequency of the laser pulses is 10⁵~10¹²HZ, pulse power is 0.5-3.5W, pulse width is 2.5-4.5 ms, pulse scanning speed is 2-20 mm/s, and pulse spot diameter is 2-10 mm. The parameter design of the laser pulse is matched according to the thickness of the densified deposition blank layer, so that the size of the finally prepared part or material is the same as that of the part model or the material model.

Has the advantages that: (1) the invention belongs to a precise additive manufacturing method, adopts the cyclic working procedures of slicing, spray deposition, densification and spray deposition, and can directly form parts with complex structures and higher precision; the step of spray atomization deposition can refine grains, inhibit element segregation, enable the obtained blank of the deposition blank to have fine, round and uniform grains and reduce or eliminate stress concentration; the densification eliminates the gap in the deposition blank, improves the density and improves the fatigue resistance and the mechanical property; belongs to the near net shaping technology, reduces or eliminates subsequent machining procedures and improves the efficiency.

(2) In the preparation method, the thickness design of each layer of spray atomization deposition and the thickness design of each layer after densification treatment are designed to ensure that the finally prepared part or material is the same as the size of a part model or a material model, and can be obtained only through a large number of verifications, and the method needs adaptive adjustment according to different metal materials.

(3) In the preparation method, in the process of spray atomization and deposition, the temperature of the substrate is controlled to be 0.2-0.6T, the liquid phase in the metal deposited on the substrate can be guaranteed not to be instantly quenched to be solid, enough fluidity is provided to fill the lap joint type gap formed by lapping of metal powder, the elimination of the gap is facilitated, the density is improved, the design of the gas-liquid mass flow rate of the atomizing gas and the metal liquid enables the metal liquid to have proper liquid-solid ratio when the metal liquid is sprayed and deposited on the substrate, the temperature of the atomized melt is 1.05-1.3 Tm, and the uniformity of liquid metal components can also be guaranteed.

(4) The preparation method solves the problems that crystal grains which cannot be solved in the traditional preparation method of the large-sized super-large part are thick, components are uneven, a second phase is thick and uneven in distribution, shrinkage cavities and shrinkage porosity are formed, and the mechanical property of a cast part is poor.

(5) The method can also be used for preparing the composite material, namely spraying and atomizing a layer of base material, then paving a layer of reinforcing material, spraying a layer of base material, and paving a layer of reinforcing material to finally obtain the composite material. The thickness of the deposition layers of the prepared composite material base material layer and the prepared composite material reinforcing material layer is controllable, and the deposition layers are the basis of precise forming; after the base material and the reinforcing material are compounded, the structure of each layer of the material is clear, and different properties of each layer of the material, such as electricity, heat, sound, magnetism and the like, are easily utilized; the reinforcing material can be fibrous and is not limited to powder particles during simultaneous spray deposition; can be directly used for forming parts, while the spray deposition can only be used for preparing materials.

Detailed Description

The present invention will be described in detail with reference to the following embodiments.

Embodiment 1:

the embodiment provides a method for preparing a 4Cr5MoSiV1 small part by synchronous spray atomization deposition and densification, which comprises the following steps:

s1: and (3) slicing the part model: slicing the part model along the Z-axis direction by adopting a computer technology, wherein the thickness of each slice layer is 0.1mm, and generating a contour track of a solid part of each slice layer;

s2: primary spray atomization deposition: controlling the distance between the nozzle and the substrate to be 100mm, controlling the movement track of the nozzle for spray atomization deposition, and performing spray atomization deposition on 4Cr5MoSiV1 metal liquid meeting the component and temperature of a part according to the outline track corresponding to the solid part of the first layer of slice layer to ensure that the metal liquid is atomized and deposited on the substrate to form a first layer of deposition blank layer with the thickness of 0.11mm and the outline same as that of the first layer of slice layer;

in the process of spray atomization deposition, the temperature of a substrate is controlled to be about 480 ℃, the atomization gas is nitrogen, the gas-liquid mass flow rate of the atomization gas and the metal liquid is 0.8, the spray distance is 100mm, and the temperature of an atomized melt is about 1440 ℃, wherein Tm is the melting point of the metal to be processed;

s3: primary densification treatment: stopping spraying and atomizing the molten metal, and continuously introducing atomizing gas while densifying the first deposition blank layer, wherein the thickness of the first deposition blank layer is equal to h after densifying;

during the mechanical compaction process, the temperature of a punch is about 600 ℃, wherein Tm is the melting point of the metal to be processed; the downward moving speed of the punch is 10 mm/s; the frequency of punch compaction is 100 times/min, and the punch reduction is 0.01 mm.

S4: trimming: and repairing the defects of burrs, fins, increased width and the like caused by the transverse flow of the metal after the densification treatment, and removing redundant materials.

S5: the distance between the nozzle and the uppermost deposition blank layer on the substrate is controlled to be constant all the time, and the operation is circularly carried out in the sequence of the spray atomization deposition and the densification treatment in the completely same way in S2 and S3 until the product with the same size and shape as the part model is obtained.

Embodiment 2:

the embodiment provides a method for preparing a large part made of 4Cr5MoSiV1 material by synchronous spray atomization deposition and densification, which is substantially the same as embodiment 1, and has the difference that:

the spray atomization deposition in step S2 and the densification process in step S3 are not densification after spray atomization deposition of a layer of deposition blank, but densification process while spray atomization deposition.

Otherwise, this embodiment is identical to embodiment 1, and will not be described herein.

Embodiment 3:

the embodiment provides a method for preparing a small-sized part made of Al-20Si materials by synchronous spray atomization deposition and densification, which is almost the same as the embodiment 1, and has the difference that:

and (4) performing the spray atomization deposition in the step (S2) in a closed type, introducing 0.1MPa of nitrogen into the closed chamber before the spray atomization deposition, lasting for 10min, then exhausting and decompressing the closed chamber to stabilize the air pressure of the closed chamber to be 0.06MPa, and then performing the spray atomization deposition.

Otherwise, this embodiment is identical to embodiment 1, and will not be described herein.

Embodiment 4:

the embodiment provides a method for preparing a 4Cr5MoSiV1 small part by synchronous spray atomization deposition and densification, which is substantially the same as embodiment 1 and has the following difference:

the thickness of each sliced layer was 0.1mm in step S1.

In the densification process in step S3, the densification process is performed by laser pulse compaction in which the frequency of laser pulses is 10¹⁰HZ, pulse power of 2.5W, pulse width of 3.0ms, pulse scanning speed of 10mm/s, and pulse spot diameter of 8 mm.

Otherwise, this embodiment is identical to embodiment 1, and will not be described herein.

Embodiment 5:

the embodiment provides a preparation method of a composite material consisting of a base material Al and a reinforcing material SiC, which is synchronously sprayed, atomized, deposited and densified, and comprises the following steps:

s1: and (3) slicing the composite material model: slicing the composite material model along the Z-axis direction by adopting a computer technology, alternately slicing the front and rear slicing layers with the thicknesses of 0.4mm and 0.1mm respectively, and generating a contour track of the solid part of each slicing layer;

s2: primary spray atomization deposition: controlling the distance between the nozzle and the substrate to be 100mm, controlling the movement track of the nozzle for spray atomization deposition, and performing spray atomization deposition on the base material Al metal liquid meeting the component and temperature of the part according to the outline track corresponding to the solid part of the first sliced layer to ensure that the base material Al metal liquid is atomized and deposited on the substrate to form a first base material layer with the thickness of 0.44mm and the outline same as that of the first sliced layer;

spraying a reinforcing material on the first base material layer to form a first reinforcing material layer, wherein the thickness of the first reinforcing material layer is 0.11 mm;

in the process of spray atomization deposition, the temperature of a substrate is controlled to be about 260 ℃, the atomization gas is nitrogen, the gas-liquid mass flow rate of the atomization gas and the matrix material Al metal liquid is 0.8, the spray distance is 100mm, the temperature of an atomized melt is about 720 ℃, and Tm is the melting point of the metal to be processed;

s3: primary densification treatment: stopping spraying and atomizing the molten metal, continuously introducing atomizing gas, and performing densification treatment on the first base material layer and the first reinforcing material layer, wherein after the densification treatment, the total thickness of the first base material layer and the first reinforcing material layer is equal to 0.5 mm.

During the mechanical compaction process, the temperature of a punch is about 340 ℃, wherein Tm is the melting point of the metal to be processed; the downward moving speed of the punch is 10 mm/s; the frequency of punch compaction was 100 times/min and the punch reduction was 0.05 mm.

S4: trimming: and repairing the defects of burrs, fins, increased width and the like caused by the transverse flow of the base material or the reinforcing material after densification treatment, and removing redundant materials.

S5: the distance between the nozzle and the uppermost deposition blank layer on the substrate is controlled to be constant all the time, and the operation is circularly carried out in the sequence of the spray atomization deposition and the densification treatment in the completely same way in S2 and S3 until the product with the same size and shape as the part model is obtained.

The parts prepared in embodiments 1 to 6 were subjected to performance tests, and the results of the performance tests are shown in table 1 below.

TABLE 1

Performance of	Density (%)	Grain size (mum)	Mechanical Properties (different materials for examples, not good specific comparison)
				Embodiment mode 1	98~99.5	2~20	Good taste
Embodiment mode 2	98~99.5	2~20	Good taste
				Embodiment 3	98~99.5	2~20	Good taste
Embodiment 4	98~99.5	2~20	Good taste
				Embodiment 5	98~99.5	2~20	Good taste
Embodiment 6	98~99.5	2~20	Good taste
				Alloy prepared by traditional casting method	90~95	50~200	Difference (D)

As can be seen from table 1 above, the density of the part or material prepared by the method described in embodiments 1 to 6 is greatly improved, the voids in the product are substantially eliminated, the stress concentration is reduced, and the fatigue resistance and mechanical properties of the material or part are improved; the grain size is greatly reduced, and the effect of fine grain strengthening is achieved; good mechanical properties including tensile strength, hardness, yield strength, fatigue strength, toughness, plasticity and the like. The above embodiments are merely illustrative of the technical concepts and features of the present invention, and the purpose of the embodiments is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.