A method for forming a metal powder injection combined with 3D printing and an interface catalyst

Abstract

A metal powder injection and 3D printing combined forming method and interface catalyst, relate to the technical field of 3D printing, the forming method comprises the following steps, S1: metal powder, binder and the interface catalyst are mixed, and injection molding is metal wire or metal particle;S2: the metal wire or metal particle is placed in the 3D printer and prints out the green body of preset shape;S3: the green body is integrated by removing the burning, and the metal product is prepared.Utilize the metal product preparation process of the forming method of the application, by adding the interface catalyst of the application, the oxide film layer on the surface of the metal powder is decomposed and disappears due to the effect of the interface catalyst, the interface of the metal particle is purified, the solid particle is super-clean sintering fusion, and the microstructure interface of the final part is super-clean, so that the mechanical performance reaches the performance index requirement of the rolling state.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of 3D printing technology, in particular to a metal powder injection and 3D printing combined forming method and an interface catalyst. BACKGROUND

[0002] 3D printing, also known as additive manufacturing or layer manufacturing, is a technology that uses powder-like metal or plastic and other materials that can be bonded to construct objects layer by layer based on digital model files. This technology was first proposed in the United States in the mid-1980s. 3D printing is often used in mold manufacturing and industrial design to manufacture models, and has gradually been used for the direct manufacturing of some products, having a profound impact on traditional process flow, production line, factory model, and industry chain combination, and is a representative disruptive technology in the manufacturing industry.

[0003] Selective laser melting is a metal 3D printing technology that can quickly manufacture parts identical to CAD models through laser sintering. Selective laser melting has been widely used. Selective laser melting uses high-power lasers to melt metal powder and builds parts / components layer by layer through 3D CAD input, which can successfully manufacture components with complex internal channels. Although additive manufacturing generally has qualified room temperature strength and elongation performance, the metal material of the printed part usually shows lower fatigue performance and high-temperature creep performance.

[0004] Metal injection molding includes mixing powder metal with a binder to form a raw material. Then, the mixture is injection molded using equipment similar to injection molding equipment used in the plastics industry, which forms a "green body". The green body has sufficient rigidity and strength, and then the green body is further processed to remove the binder and sinter the metal powder particles to form the final product. Further processing of the green body includes removing the binder and sintering. The specific sintering step includes heating the body to metallurgically bond individual metal particles together. Sintering in metal injection molding part production is usually similar to sintering used in traditional powder metal part production.

[0005] Currently, metal blanks are prepared by metal injection molding or metal 3D printing forming method during the process of manufacturing products with corresponding required structures. Both methods have their own advantages, but they also have the defects of low production efficiency and high production cost. Moreover, although metal injection molding and 3D printing are suitable for most metal production products, some metals will form an oxide layer on the surface of the metal particles during the metal 3D printing process. The presence of the aluminum oxide layer will cause the metal powder after melting to not fit closely enough, thereby affecting the product performance of the printed part. For example, aluminum is less used in metal injection molding because the adhered aluminum oxide film on the surface of aluminum or aluminum alloy particles will inhibit sintering, thereby affecting the performance of the printed product.

[0006] CN 106984805 B discloses a kind of 3D printing feed and its preparation method and application.The feed is high polymer binder wrapped metal powder, and is linear.The linear feed is printed into green body of preset shape via 3D printer, and then sequentially goes through debinding, sintering, and metal products with complex structure and high precision can be obtained.The debinding mode in prior art is hot debinding, water debinding, acid debinding or organic solvent debinding, wherein hot debinding is oxidative debinding under air condition, and then the workpiece is cooled and sent to vacuum sintering furnace for sintering.This debinding mode is complicated in operation process and high in energy consumption on the one hand, and on the other hand, the metal parts printed by using the method will still have the problem of low product strength and weak compactness due to the existence of metal surface layer oxide film, which will stay in the final product crystal structure in the form of genetic transmission. SUMMARY

[0007] The present application aims to provide a metal powder injection and 3D printing combined forming method and interface catalyst to solve the technical problem of the influence of the oxidation layer on the surface of metal particles on the performance of the workpiece.

[0008] To solve the above technical problems, the specific solution adopted by the present application is that an interface catalyst is composed of the following raw materials in mass percentage: polyethylene 95-98.5%, paraffin 0.8-4.0%, polyvinyl chloride 0.2-0.8%, polytetrafluoroethylene 0.1-0.5%, and organic solvent 0.05-0.3%.

[0009] As a further optimization of the above technical solution, the interface catalyst is composed of the following raw materials in mass percentage: polyethylene 98%, paraffin 1.0%, polyvinyl chloride 0.6%, polytetrafluoroethylene 0.3%, and acetone 0.1%.

[0010] Application of an interface catalyst in 3D printing.

[0011] A metal powder injection and 3D printing combined forming method, comprising the following steps,

[0012] S1: mixing metal powder, binder and the above-mentioned interface catalyst, and injection molding into metal wire or metal particles;

[0013] S2: placing the metal wire or metal particles in a 3D printer to print a green body of preset shape;

[0014] S3: carrying out debinding and sintering integrated treatment on the green body to obtain a metal product.

[0015] As a further optimization of the above technical solution, the metal powder is aluminum alloy powder.

[0016] As the further optimization of the above technical solution, the volume ratio of the metal powder, the binder and the interface catalyst is 116-124:73-82:1-3.

[0017] As the further optimization of the above technical solution, in step S3, the debinding and sintering integration treatment is to debind and sinter the green compact in a vacuum environment.

[0018] As the further optimization of the above technical solution, the debinding condition is that the vacuum pressure is 1.0*10 -1 ~ 50*10 -1 Pa, and the temperature is 200-500℃; the sintering condition is that the vacuum pressure is 1.0*10 -1 ~ 50*10 -1 Pa, and the temperature is 540-650℃.

[0019] As the further optimization of the above technical solution, in step S1, the pressure of the injection molding is 70-80MPa, and the temperature is 140-180℃.

[0020] As the further optimization of the above technical solution, the diameter of the metal wire is 0.8-1.2mm, and the diameter of the metal particle is 2.0-4.0mm.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] In the process of preparing the metal product by using the molding method of the present application, by adding the interface catalyst of the present application, the oxide film layer on the surface of the metal powder is decomposed and disappears due to the effect of the interface catalyst, the interface of the metal particle is purified, the solid particle is super-cleanly sintered and fused, and finally the microstructure interface of the part is super-clean, so that the mechanical performance reaches the performance index requirement of the rolled state.

[0023] The present application completes the whole process of debinding and sintering in a vacuum environment in a vacuum furnace. In the process of debinding, the interface catalyst completes the layer-by-layer decomposition and gasification process of the aluminum alloy surface oxide. Al2O3+HCl=H2O+AlCl3(>200℃ under pressure as a gas), without the need to first cool the workpiece after debinding and then sinter, the production and processing operation steps are simplified, the energy consumption is reduced, and the production efficiency is improved.

[0024] The vacuum debinding and sintering integration of the present application is in a vacuum environment, which also reduces the CO2 emission and causes less environmental pollution. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The figure is a flowchart of the molding method in the present application;

[0026] Figure 2A schematic diagram of the principle of disappearance of the surface oxide film of the metal powder in the de-burning integrated process;

[0027] Figure 3 A photo of the aluminum alloy workpiece prepared in Comparative Example 1;

[0028] Figure 4 A photo of the aluminum alloy workpiece prepared in Example 2. DETAILED DESCRIPTION

[0029] The technical solutions of the present application will be further described in detail below in combination with the drawings and specific examples. The parts not described and disclosed in detail in the following examples of the present application should be understood as the prior art known or should be known by the skilled in the art.

[0030] Example 1

[0031] An interface catalyst for a 3D printing process of metal powder. The catalyst is composed of the following raw materials in mass percentage: polyethylene 95-98.5%, polyvinyl chloride 0.1-0.8%, polytetrafluoroethylene 0.1-0.5%, and organic solvent 0.1-0.9%.

[0032] The preparation process of the interface catalyst is the general preparation process of catalysts. The above-mentioned percentages of polyethylene, paraffin, polyvinyl chloride, polytetrafluoroethylene, and organic solvent are mixed and stirred.

[0033] Some metals will form an oxide layer on the surface of metal particles during the 3D printing process of metals. The presence of the oxide layer will cause the metal powder after melting to not fit closely enough, thereby affecting the product performance of the printed part. Taking aluminum alloy powder as an example, the surface layer of the aluminum alloy powder will form an oxide film mainly composed of aluminum oxide.

[0034] The interface catalyst designed in the present application can make the oxide film layer on the surface of the metal powder decompose and disappear due to the action of the interface catalyst, complete the purification treatment of the metal particle interface, and super-clean sintering fusion of the solid particles.

[0035] The vaporization method of the oxide film of aluminum alloy is as follows: 1) co-heating with liquid ammonia or concentrated sulfuric acid, or co-melting with potassium hydroxide, none of which reacts. It is not reduced by hydrogen, does not decompose under strong heat but sublimates, and is very stable in nature. Under the condition of the simultaneous presence of fluorine and chlorine, the oxide film can be synthesized into aluminum fluoride, aluminum chloride and water; under the condition of 200 degrees or above and high vacuum (1 Pa or below), it sublimates into gaseous substances and is discharged from the furnace body with PE vapor molecules. 2) Properties of aluminum oxide: Al2O3+6HCl=2AlCl3+3H2O.

[0036] Aluminum chloride is white granules or powder, with strong hydrochloric acid smell, industrial product is light yellow. Easily soluble in water, alcohol, chloroform, carbon tetrachloride, slightly soluble in benzene. Melting aluminum chloride is not easy to conduct electricity, and most of the halogen ion containing salt (such as sodium chloride) is different. The aqueous solution of aluminum chloride is completely dissociated and is a good conductor. Anhydrous aluminum chloride sublimates at 178℃, its vapor is associated with double molecules. It can absorb moisture in the air, and part of the hydrolysis releases hydrogen chloride. AlCl3 adopts "YCl3" structure, which is Al cubic closest packing layer structure, while Al in AlCl3 occupies the adjacent tetrahedral interstitial space of Cl closest packing framework.

[0037] Aluminum chloride is colorless transparent crystal or white and slightly light yellow crystalline powder. It can easily absorb moisture and partially hydrolyze to release hydrogen chloride to form acid mist. It is easily soluble in water and strongly hydrolyzed, and the solution is acidic. It is also soluble in ethanol and diethyl ether, while releasing a large amount of heat. The aluminum chloride hexahydrate is colorless orthorhombic crystal, the density is 2.398g / cm 3 , decomposed at 100℃. The coexistence of fluorine and chlorine helps to catalyze the interface synthesis reaction at 200-500℃; the final product of the reaction is aluminum chloride and aluminum fluoride, and the reaction is synchronized with the process of degreasing.

[0038] Example 2

[0039] The application discloses a metal powder injection and 3D printing combined forming method, which adds the above-mentioned interface catalyst, and specifically comprises the following steps,

[0040] S1: mixing the metal powder, the binder and the above-mentioned interface catalyst, and injection forming into metal wires or metal particles;

[0041] The metal powder is selected to be aluminum powder or aluminum alloy powder, in the embodiment, the metal powder is aluminum alloy powder, the binder is plastic, and the interface catalyst is composed of raw materials with the following mass percentages: 98% of polyethylene, 1.0% of paraffin, 0.6% of polyvinyl chloride, 0.3% of polytetrafluoroethylene and 0.1% of acetone. The volume ratio of the metal powder, the binder and the interface catalyst is 124:73:3.

[0042] The metal powder, the binder and the interface catalyst are stirred and mixed, and then injection forming is performed under the conditions of a pressure of 80MPa and a temperature of 140-180℃ to form metal wires or metal particles, the diameter of the metal wires is 0.8-1.2mm, and the diameter of the metal particles is 2.0-4.0mm.

[0043] In the embodiment, the metal powder, the binder and the interface catalyst are stirred and mixed, and then injection forming is performed to form metal wires, the diameter of the metal wires is 1.0mm, and the pore rate of the metal wires is less than 0.4% under a microscope.

[0044] S2: Put the metal wire into the 3D printer to print a green body with a preset shape;

[0045] The temperature of 3D printing is set to be 20-60 DEG C lower than the decomposition temperature of the binder, and the temperature in this embodiment is 200 DEG C. At this temperature, the metal wire is melted by the binder during 3D printing to print a part blank, and the porosity of the blank is less than 1.2%. In this embodiment, since the plastic binder is added, the temperature during 3D printing is lower, so the stress of the product is also lower. Compared with the printing of general high-temperature melting metal particles, the product stability of this printing technology is stronger, and the application range is wider.

[0046] S3: The green body is subjected to debinding and sintering integration treatment, and a metal product is obtained.

[0047] The debinding and sintering integration process is carried out in a vacuum environment, including debinding and sintering two links. The environmental conditions of the debinding process are: vacuum pressure 1.0*10 -1 ~ 50*10 -1 Pa, temperature 200-500 DEG C; the environmental conditions of the sintering process are: vacuum pressure 1.0*10 -1 ~ 50*10 -1 Pa, temperature 540-650 DEG C.

[0048] In this embodiment, the temperature condition of the debinding link is 420 DEG C, and the vacuum pressure is 1*10 -1 Pa; the temperature condition of the sintering link is 600 DEG C, and the vacuum pressure is 1*10 -1 Pa.

[0049] In this embodiment, the oxide film on the surface of the aluminum alloy powder is an aluminum oxide layer. The aluminum oxide layer reacts with chlorine in the presence of fluorine to generate aluminum chloride and aluminum fluoride. The boiling points of aluminum chloride and aluminum fluoride are below 200 DEG C, so they can be vaporized and sublimed in the debinding and sintering integration environment and finally discharged with the plastic gas. After the reaction and discharge of the aluminum oxide layer, the metal particle interface is purified, the solid particles are super-cleanly sintered and fused, and the microstructure interface of the final part is super-clean, so that the mechanical properties meet the performance requirements of the rolled state. During the sintering process, the plastic is gaseous at a high temperature in a vacuum environment, which is higher than the low-pressure boiling point of the plastic.

[0050] In the debinding and sintering integration process of the present application, the oxide film of the aluminum alloy is vaporized, and 15-20% of the diameter of the metal aluminum alloy powder can be melted. In a vacuum environment, the melted metal aluminum alloy powder shrinks into a spherical shape due to surface tension, and the melted metal aluminum alloy powder is used to fill the gap between adjacent particles, thereby improving the mechanical properties of the final workpiece.

[0051] The mechanical properties of the prepared AlSi10Mg aluminum alloy material are as follows: yield strength: 310 MPa, tensile strength: 475 MPa, and elongation: 11%.

[0052] Embodiment 3

[0053] The embodiment discloses a metal powder injection and 3D printing combined forming method, which adds the interface catalyst, and specifically comprises the following steps,

[0054] S1: mixing the metal powder, the binder and the interface catalyst, and injection molding into a metal wire;

[0055] Specifically, the metal powder is selected as an aluminum alloy powder, the binder is plastic, and the interface catalyst is composed of raw materials with the following mass percentages: polyethylene 95%, paraffin 4.0%, polyvinyl chloride 0.2%, polytetrafluoroethylene 0.5%, and acetone 0.3%. The adding amount ratio of the metal powder, the binder and the interface catalyst is 116:82:1.

[0056] The metal powder, the binder and the interface catalyst are stirred and mixed, and injection molded into a metal wire under the conditions of a pressure of 80 MPa and a temperature of 140-180℃. The diameter of the metal wire is 0.8 mm, and the porosity of the metal wire is less than 0.5% under a microscope.

[0057] S2: placing the metal wire in a 3D printer to print a green body with a preset shape;

[0058] The temperature of the 3D printing is set to be 20-60℃ lower than the decomposition temperature of the binder. In this embodiment, the temperature is 210℃. Under this temperature condition, the metal wire is melted by the binder during the 3D printing process to print a part blank. The porosity of the blank is less than 1.1%.

[0059] S3: carrying out debinding and sintering integrated treatment on the green body to obtain a metal product.

[0060] In this embodiment, the temperature condition of the debinding link is 200℃, and the vacuum pressure is 3*10 -1 Pa; the temperature condition of the sintering link is 540℃, and the vacuum pressure is 1*10 -1 Pa.

[0061] The oxidation film of the aluminum alloy in the debinding and sintering integrated process is an aluminum oxide layer. The aluminum oxide layer reacts with chlorine in the presence of fluorine to generate aluminum chloride and aluminum fluoride. The boiling points of aluminum chloride and aluminum fluoride are below 200℃, so they can be vaporized and sublimated in the debinding and sintering integrated environment and finally discharged with the plastic gas. After the aluminum oxide layer is reacted and discharged, the interface of the metal particles is cleaned, the solid particles are super-cleanly sintered and fused, and the microstructure interface of the final part is super-clean, so that the mechanical properties reach the performance index requirements of the rolled state. During the sintering process, the plastic will be gasified under vacuum and high temperature, which is higher than the low-pressure boiling point of the plastic.

[0062] It is detected that the mechanical properties of the prepared AlSi10Mg aluminum alloy material are as follows: yield strength: 321 MPa, tensile strength: 487 MPa, and elongation: 8.0%.

[0063] Example 4

[0064] The embodiment discloses a forming method combining metal powder injection with 3D printing, which adds the above-mentioned interface catalyst and specifically comprises the following steps,

[0065] S1: mixing the metal powder, the binder and the above-mentioned interface catalyst, and injection molding into a metal wire;

[0066] Specifically, the metal powder is selected as an aluminum alloy powder, the binder is plastic, and the interface catalyst is composed of the following raw materials in mass percentage: polyethylene 95%, paraffin 4.0%, polyvinyl chloride 0.45%, polytetrafluoroethylene 0.5%, and acetone 0.05%. The adding amount ratio of the metal powder, the binder and the interface catalyst is 124:75:2.

[0067] The metal powder, the binder and the interface catalyst are stirred and mixed, and injection molded into a metal wire under the conditions of a pressure of 80 MPa and a temperature of 140-180℃. The diameter of the metal wire is 1.2 mm, and the metal wire is a plastic aluminum wire. The porosity of the metal wire is less than 0.3% under a microscope.

[0068] S2: placing the metal wire in a 3D printer to print a green body with a preset shape;

[0069] The temperature of the 3D printing is set to be 20-60℃ lower than the decomposition temperature of the binder. In this embodiment, the temperature is 210℃. Under this temperature condition, the binder is melted during the 3D printing of the metal wire, so that a part blank is printed. The porosity of the blank is less than 1.2%.

[0070] S3: carrying out debinding and sintering integrated treatment on the green body to obtain a metal product.

[0071] The temperature condition of the debinding link in this embodiment is 500℃, and the vacuum pressure is 5*10 -1 Pa; the temperature condition of the sintering link is 650℃, and the vacuum pressure is 5.0*10 -1 Pa.

[0072] In the process of debinding and sintering integration, the oxidation film of the aluminum alloy gasifies. In this embodiment, the oxidation film on the surface of the aluminum alloy powder is an aluminum oxide layer. The aluminum oxide layer reacts with chlorine in the presence of fluorine to generate aluminum chloride and aluminum fluoride. The boiling points of aluminum chloride and aluminum fluoride are below 200℃, so they can be vaporized and sublimated in the environment of debinding and sintering integration, and finally discharged with the plastic gas. After the aluminum oxide layer is reacted and discharged, the interface of the metal particles is purified, the solid particles are super-cleanly sintered and fused, and the microstructure interface of the final part is super-clean, so that the mechanical properties meet the performance index requirements of the rolled state. During sintering, the plastic will gasify under vacuum and high temperature, which is higher than the low-pressure boiling point of the plastic.

[0073] Through detection, the mechanical properties of the prepared AlSi10Mg aluminum alloy material are as follows: yield strength: 305MPa, tensile strength: 462MPa, and elongation: 11.5%.

[0074] Embodiment 5

[0075] This embodiment discloses a forming method combining metal powder injection with 3D printing, which adds the above-mentioned interface catalyst and specifically includes the following steps,

[0076] S1: mixing the metal powder, the binder and the above-mentioned interface catalyst, and injection molding into a metal wire;

[0077] Specifically, the metal powder is selected as an aluminum alloy powder, the binder is plastic, and the interface catalyst is composed of the following raw materials in mass percentage: polyethylene 98.5%, paraffin 0.9%, polyvinyl chloride 0.2%, polytetrafluoroethylene 0.1%, and acetone 0.3%. The adding amount ratio of the metal powder, the binder and the interface catalyst is 120:73:3

[0078] The metal powder, the binder and the interface catalyst are stirred and mixed, and injection molded into a metal wire under the conditions of a pressure of 80MPa and a temperature of 140-180℃. The diameter of the metal wire is 1.1mm, and the metal wire is a plastic aluminum wire. The porosity of the metal wire is less than 0.3% under a microscope.

[0079] S2: placing the metal wire in a 3D printer to print a green body with a preset shape;

[0080] The temperature of 3D printing is set to be 20-60℃ lower than the binder decomposition temperature, and the temperature in this embodiment is 210℃. At this temperature, the metal wire is melted by the binder during 3D printing to print a part blank, and the porosity of the blank is less than 1.2%;

[0081] S3: The green body is subjected to debinding and sintering integration treatment to obtain a metal product.

[0082] In this embodiment, the temperature condition of the debinding link is 300℃, and the vacuum pressure is 1*10 -1 Pa; and the temperature condition of the sintering link is 550℃, and the vacuum pressure is 1.0*10 -1 Pa.

[0083] During the debinding and sintering integration, the oxide film of the aluminum alloy gasifies. In this embodiment, the oxide film on the surface of the aluminum alloy powder is an aluminum oxide layer. The aluminum oxide layer reacts with chlorine in the presence of fluorine to generate aluminum chloride and aluminum fluoride. The boiling points of aluminum chloride and aluminum fluoride are below 200℃, so they can be vaporized and sublimated in the debinding and sintering integration environment and finally discharged with the plastic gas. After the aluminum oxide layer is reacted and discharged, the interface of the metal particles is cleaned, the solid particles are super-cleanly sintered and fused, and the microstructure interface of the final part is super-clean, so that the mechanical properties meet the performance requirements of the rolled state. During sintering, the plastic will gasify under vacuum and high temperature, which is higher than the low-pressure boiling point of the plastic.

[0084] After detection, the mechanical properties of the prepared AlSi10Mg aluminum alloy material are: yield strength: 300MPa, tensile strength: 465MPa, and elongation: 12%.

[0085] Embodiment 6

[0086] This embodiment discloses a forming method combining metal powder injection with 3D printing, which adds the above-mentioned interface catalyst and specifically includes the following steps,

[0087] S1: Mixing the metal powder, the binder and the above-mentioned interface catalyst, and injection molding into a metal wire;

[0088] Specifically, the metal powder is selected to be an aluminum alloy powder, the binder is plastic, and the interface catalyst is composed of the following raw materials in mass percentage: polyethylene 98.5%, paraffin 0.9%, polyvinyl chloride 0.2%, polytetrafluoroethylene 0.1%, and acetone 0.3%. The adding amount ratio of the metal powder, the binder and the interface catalyst is 120:73:3

[0089] The metal powder, the binder and the interface catalyst are mixed by stirring, and are injection molded into a metal wire under the conditions of a pressure of 80 MPa and a temperature of 140-180°C. The diameter of the metal wire is 1.1 mm. The metal wire is the plastic aluminum wire. The porosity of the metal wire is less than 0.3% under a microscope.

[0090] S2: The metal wire is placed in a 3D printer to print a green body of a preset shape.

[0091] The temperature of 3D printing is set to be 20-60°C lower than the decomposition temperature of the binder. In this embodiment, the temperature is 210°C. Under this temperature condition, the metal wire is melted by the binder in the process of 3D printing, so that a part blank is printed. The porosity of the blank is less than 1.2%.

[0092] S3: The green body is subjected to debinding and sintering integration, so that a metal product is prepared.

[0093] In this embodiment, the temperature condition of the debinding link is 300°C, and the vacuum pressure is 50*10 -1 Pa. The temperature condition of the sintering link is 550°C, and the vacuum pressure is 50*10 -1 Pa.

[0094] In the process of debinding and sintering integration, the oxidation film of the aluminum powder is gasified. The oxidation film on the surface of the aluminum powder is an aluminum oxide layer. The aluminum oxide layer reacts with chlorine in the presence of fluorine to generate aluminum chloride and aluminum fluoride. In the debinding and sintering integration environment, the aluminum chloride and the aluminum fluoride can be vaporized and sublimated, and finally are discharged with plastic gas. After the reaction and discharge of the aluminum oxide layer, the interface of the metal particles is completely purified, the solid particles are super-cleanly sintered and fused, the microstructure interface of the final part is super-clean, and the mechanical properties meet the performance index requirements of the rolled state.

[0095] Embodiment 7

[0096] The overall steps of this embodiment are the same as those of embodiment 2. The difference is that in this embodiment, the metal powder, the binder and the above-mentioned interface catalyst are mixed, and are injection molded into metal particles with a diameter of 3.0 mm. Then, the metal particles are placed in a 3D printer to print a green body of a preset shape. The debinding and sintering integration are carried out in the manner of embodiment 2, so that a metal product is prepared.

[0097] In this embodiment 7, the oxidation film on the surface of the aluminum alloy powder is an aluminum oxide layer. The aluminum oxide layer reacts with chlorine in the presence of fluorine to generate aluminum chloride and aluminum fluoride. The boiling points of the aluminum chloride and the aluminum fluoride are below 200°C. Therefore, in the debinding and sintering integration environment, the aluminum chloride and the aluminum fluoride can be vaporized and sublimated, and finally are discharged with plastic gas. After the reaction and discharge of the aluminum oxide layer, the interface of the metal particles is completely purified, the solid particles are super-cleanly sintered and fused, the microstructure interface of the final part is super-clean, and the mechanical properties meet the performance index requirements of the rolled state.

[0098] Comparative Example 1

[0099] The comparative example is generally the same as the steps of Example 2, the difference is that the metal wire of the comparative example is formed by injection molding of a mixture of metal powder and binder, without adding the interface catalyst in the application.

[0100] It is detected that the mechanical properties of the AlSi10Mg aluminum alloy material prepared in the comparative example are: yield strength: 226 MPa, tensile strength: 338 MPa, elongation 3.5%.

[0101] Comparative Example 2

[0102] The comparative example is generally the same as the steps of Example 2, the difference is that the comparative example does not go through the debinding and sintering integration of Example 2. In step S3, the metal wire is placed in the 3D printer to print a green body of a predetermined shape, and then debinding is carried out in an air environment, and after cooling, it is sent into a vacuum furnace for sintering treatment.

[0103] It is detected that the mechanical properties of the metal product AlSi10Mg aluminum alloy material prepared in the comparative example are: yield strength: 253 MPa, tensile strength: 368 MPa, elongation 5.5%.

[0104] Result analysis: the difference between Comparative Example 1 and Example 2 is that no interface catalyst of the application is added in Comparative Example 1, so the yield strength, tensile strength and elongation of the prepared aluminum alloy material are all weaker than those of Example 2.

[0105] Figure 3 The photo shown is of the metal product prepared in Comparative Example 1, and it can be seen that the product prepared has grain boundary defects, and the defect site is an early crack source that exists oxide inclusions that hinder the fusion of the interface. Figure 4 The photo shown is of the metal product added with the surfactant of the application. Since the oxides of the metal powder disappear, the interface fusion is good without defects, and its macroscopic mechanical properties are similar to those of the rolled and cast states. The addition of the interface catalyst in Example 2 removes the oxide film on the surface of the aluminum alloy powder, and the combination between the aluminum alloy powder particles is more dense, thereby improving the mechanical properties of the prepared product.

[0106] Comparative Example 2 and Example 2 both add the interface catalyst of the application, but Comparative Example 2 does not go through the debinding and sintering integration, so the oxide film on the surface of the aluminum alloy powder still exists during the debinding process, thereby affecting the mechanical properties of the prepared product.

[0107] The above merely provides the preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method of forming a metal powder injection combined with 3D printing, characterized in that, The method comprises the following steps, S1: mixing metal powder, binder and interface catalyst, and injection molding into metal wire or metal particles; the interface catalyst is composed of the following raw materials in mass percentage: polyethylene 95-98.5%, paraffin 0.8-4.0%, polyvinyl chloride 0.2-0.8%, polytetrafluoroethylene 0.1-0.5% and organic solvent 0.05-0.3%; the metal powder is aluminum alloy powder; S2: placing the metal wire or metal particles in a 3D printer to print a green body with a preset shape; S3: the green compact is subjected to debinding and sintering integration treatment, i.e. a metal product is prepared; wherein the debinding and sintering integration treatment is debinding and sintering of the green compact under a vacuum environment, the debinding condition is a vacuum pressure of 1.0*10 -1 ~50*10 -1 Pa and a temperature of 200-500 ℃; and the sintering condition is a vacuum pressure of 1.0*10 -1 ~50*10 -1 Pa and a temperature of 540-650 ℃.

2. A method of forming a metal powder injection molding in combination with 3D printing according to claim 1, characterized in that, The interface catalyst is composed of the following raw materials in mass percentage: polyethylene 98%, paraffin 1.0%, polyvinyl chloride 0.6%, polytetrafluoroethylene 0.3% and acetone 0.1%.

3. A method of forming a metal powder injection molding in combination with 3D printing according to claim 1, wherein, The volume ratio of the metal powder, the binder and the interface catalyst is 116-124:73-82:1-3.

4. A method of forming a metal powder injection molding in combination with 3D printing according to claim 1, wherein, In step S1, the pressure of injection molding is 70-80 MPa, and the temperature is 140-180℃.

5. A method of forming a metal powder injection molding in combination with 3D printing according to claim 1, wherein, The diameter of the metal wire is 0.8-1.2 mm, and the diameter of the metal particles is 2.0-4.0 mm.

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