KR20220035969A - Metal powder coated with polymer material, manufacturing method and application thereof - Google Patents

Abstract

In the metal powder coated with a polymer material and its manufacturing method and application, when manufacturing the metal powder, a metal powder coated with an oxide film on the surface, a deoxidation film solution, a polymer material, and a solvent for dissolving the polymer material are mixed. When mixed, a chemical reaction occurs between the deoxidation film solution and the oxidation film to remove the oxide film, and friction between the metal powders occurs to remove the oxide film, thereby completely and effectively removing the oxide film on the surface of the metal powder. The metal powder in the obtained mixture is dried to obtain a metal powder coated with a polymer material. The metal powder is subjected to a metal injection molding process to increase the application surface of the metal material. Metal parts are manufactured using the metal powder through an injection molding process. It can produce metal parts with complex structures, small size and high density, and has excellent economic efficiency and broad application prospects.

Description

Metal powder coated with polymer material and its manufacturing method and application

The present invention relates to the field of metal materials, and more specifically, to highly active metal powders coated with polymer materials and their production methods and applications.

Highly active metals and their alloy materials are easily oxidized in air to form an oxide film. The presence of this oxide film affects the diffusion action of the metal material during high-temperature sintering, lowering the sintering density of the material and deteriorating its mechanical properties.

The surface of highly active metal alloy materials such as copper alloy, aluminum alloy, titanium alloy, and magnesium alloy is very easy to form an oxide film at room temperature. Additionally, since the melting points of the internal metal alloy and the oxides that make up the oxide film are different, the core-shell effect is likely to occur. For example, the melting points of copper and copper oxide are 1083°C and 1326°C, respectively, the melting points of aluminum and aluminum oxide are 667°C and 2054°C, and the melting points of titanium and titanium oxide are 1660°C and 1850°C. The melting points of magnesium and magnesium oxide are 649℃ and 2850℃, respectively. Failure to remove the oxide film on the surface of this highly active metal during the sintering process of powder metallurgy may cause problems such as poorer sintering in subsequent sintering and lowering of mechanical properties.

Taking aluminum alloy as an example, the thickness of the bulk aluminum alloy surface oxide film at room temperature is 10 μm to 20 μm. Aluminum alloy powder manufactured by the atomization method has an oxide film thickness of 50㎛ to 150㎛, and its properties are very stable in an amorphous state or hydrate. As can be seen from the Ellingham redox diagram, it is difficult for aluminum oxide to be decomposed and reduced to aluminum within the melting point of 667°C. When sintering under normal conditions, aluminum metal atoms in the aluminum alloy cannot diffuse and penetrate this continuous and dense Al2O3 oxide film, so it cannot be used for interdiffusion and mass transfer between aluminum alloy powder particles. Therefore, it is difficult to remove voids between particles, and metal parts manufactured using the aluminum alloy powder cannot be densified. Patent CN107584110A introduces aluminum alloys into wax-based metal injection molding. Because no special treatment is performed on the oxide film on the surface of the aluminum alloy when supplying the material, its sintering density and stability are not ideal.

In the prior art, the sintering performance of aluminum and aluminum alloys is generally improved by destroying or removing the oxide film on the surface of the metal material or through liquid phase sintering.

The main methods for destroying the oxide film are as follows.

(1) Addition of magnesium metal to carry out solid-state reaction sintering: the activity of magnesium is much greater than that of aluminum, and the free energy formed by its oxide is much more than that of Al2O3. Therefore, magnesium additives can be applied to powder sintering of aluminum alloy to reduce Al2O3 to pure metallic aluminum. At 800°C, magnesium-aluminum spinel structure (MgAl2O4) oxide begins to be generated, and magnesium diffuses in the aluminum matrix, changing the volume, and generates shear force on the oxide film, ultimately destroying the oxide film. This helps smooth diffusion of atoms and sintering, and improves the density of aluminum alloy. However, according to research, the amount of magnesium added to the aluminum alloy must reach 0.15% to cause shrinkage of the sintered volume to effectively remove the oxide film and at the same time exhibit solid solution strengthening. However, the sintering temperature of aluminum alloy is less than 667°C, and the desired effect can be achieved only by lowering the reaction temperature by utilizing the high-energy characteristics of the surface of the nano-ceramic powder particles. Therefore, the efficiency of oxide film removal within the melting point of aluminum is not good.

(2) Sintering in a reducing atmosphere: Some scholars believe that when sintering in a reducing atmosphere, the reducing gas around the particles reacts with Al2O3 and displaces metallic aluminum. Hydrogen, a commonly used reducing gas, is a very active chemical element and can cause a substitution reaction with metal oxides. Likewise, hydrogen can also react with oxide Al2O3, and during the sintering process, the Al2O3 thin film gradually becomes thinner by successive reactions, and diffusion of aluminum atoms between particles is carried out, making the bulk material dense. However, as can be seen from the Ellingham oxidation source diagram, aluminum oxide within the melting point of aluminum at 667°C is difficult to decompose and be reduced to aluminum, and its H2/H2O reaches as high as 1018 or more. Therefore, Al2O3 cannot be effectively reduced to pure metallic aluminum, so the effect of removing the oxide film is very low.

(3) Listing method in terms of liquid phase sintering: It is difficult for metal and alloy powder blanks to obtain high density through solid phase sintering alone. When components with a low melting point melt at a certain sintering temperature to form a eutectic crystal with a low melting point, the material movement due to the liquid phase is faster than the solid phase, and the liquid phase ultimately fills the voids in the sintered body. Therefore, a sintered product with high density and excellent performance can be obtained. However, the additive phase of liquid sintered aluminum alloy products must meet the following conditions: In other words, it is lower than the melting point of (A) aluminum alloy. (B) It is insoluble in aluminum and each other. (C) The resulting liquid must have excellent wettability with the aluminum alloy particle surface. Therefore, the commonly used additive phases are metals such as Cu, Sn, Zn, and Mg, or these metal elements are added in combination. For example, in the metal injection molding patent for aluminum and aluminum alloys, as mentioned in CN101594954A, a solvent degreasing system is used to add Sn, In, Sb and B as sintering aids.

(4) Addition of intermediate phase reactants: For example, patent CN104999074A adds boron oxide (B2O3) to modify the surface of aluminum and aluminum alloy, which helps the reaction of boron oxide (B2O3) with aluminum alloy powder surface oxide during the sintering process to achieve sintering. promotes. As can be seen from the diagram of the Al2O3-B2O3 phase, the melting point of boron oxide (B2O3) is 445°C, and the lowest temperature of aluminum borate (nAl2O3-B2O3) compound, which forms an amorphous state with Al2O3, is 800°C to 1000°C. This compound still has ceramic properties and remains in the aluminum alloy material, affecting its performance, and its reaction temperature is higher than the melting point of aluminum.

(5) Mechanical mutual friction of the surface oxide film: For example, as mentioned in patent CN107159878A, metal materials, polymer materials and solvents are placed in a closed container, and rotational movement is performed on a ball mill to form a surface oxide film through the contact friction action between the powders. Remove and perform coating at the same time. Since this cannot remove the oxide film on the concave surface or irregular non-contact portion within the aluminum particle, it cannot completely and effectively remove the oxide film on the outer surface of the particle.

The above-described method implements the removal of the oxide film of the metal material by independently using a physico-mechanical method or a chemical reaction method. Not only does this not achieve complete removal, but it can also effectively prevent the regeneration of the oxide film. Therefore, in most of the above-described methods, the surface of the highly active metal material can be re-oxidized after removing the oxide film. In addition, because it cannot match the subsequent sintering conditions, when high-activity metal materials are introduced into the metal injection molding (MIM) process to perform injection sintering, the sintering is not dense is always a key challenge, which industry experts and scholars urgently need to address. This is a problem that needs to be solved.

The purpose of the present invention is to provide a metal powder coated with a polymer material and a method for manufacturing the same. The method can completely and effectively remove the oxide film on the surface of the metal powder and prevent the regeneration of the oxide film. The metal powder can be applied to a metal injection molding process, and metal parts made from the metal powder have a dense structure.

In order to achieve the above-mentioned object, the technical solution adopted in the present invention is a method for producing metal powder coated with a polymer material, which includes the following steps.

(1) Mix metal powder coated with an oxide film on the surface, a deoxidation film solution, a polymer material, and a solvent for dissolving the polymer material. During the mixing process, the deoxidation film solution undergoes a chemical reaction with the oxide film to chemically remove the oxide film to obtain a mixture. The mixture includes at least a metal powder from which the oxide film has been removed or partially removed, a polymer material dissolved by the solvent, the deoxidation film solution, and a product after a chemical reaction of the oxide film.

(2) The metal powder in the mixture is dried and the solvent on the metal powder is volatilized to obtain a metal powder coated with a polymer material.

Preferably, in step (1), the mixture is subjected to at least one method of polishing, vibration, and stirring to generate mutual friction between the metal powders to physically remove the oxide film coated on the surface of the metal powder.

Preferably, in step (1), the material of the metal powder coated with an oxide film on the surface is at least one of aluminum, aluminum alloy, magnesium, magnesium alloy, titanium, titanium alloy, copper, and copper alloy.

More preferably, the aluminum alloy is an aluminum-magnesium alloy or an aluminum-magnesium-silicon alloy.

Preferably, in step (1), the deoxidation film solution is an acidic solution.

More preferably, the acidic solution is a solution containing a strong acid. The strong acid is at least one of sulfuric acid, hydrochloric acid, nitric acid, and iodic acid, or a mixture thereof.

More preferably, the acidic solution is a solution containing a medium strong acid. The medium strong acid is at least one or a mixture of oxalic acid, sulfurous acid, phosphoric acid, pyruvic acid and nitrous acid.

More preferably, the acidic solution is a solution containing a weak acid, and the weak acid is citric acid, hydrofluoric acid, malic acid, gluconic acid, formic acid, lactic acid, benzoic acid, acrylic acid, acetic acid, propionic acid, stearic acid, carbonic acid, hydrosulfate acid, hypochlorite. It is at least one of chloric acid, phenol, phosphoric acid, boric acid, and silicic acid, or a mixture thereof.

Preferably, in step (1), the deoxidation film solution is an alkaline solution.

More preferably, the alkaline solution is a solution containing alkali. The alkali is either sodium hydroxide or potassium hydroxide or a mixture thereof.

Preferably, in step (1), the polymer material is one of thermosetting plastic, thermoplastic plastic, or a mixture thereof.

More preferably, the polymer material is polyvinyl alcohol, polyethylene glycol, polyoxyethylene, polyacrylic acid, sodium polyacrylate, polyvinyl pyrroli. polyvinyl pyrrolidone, propylene glycol, diethylene glycol, triethylene glycol, polypropylene glycol, triethanolamine, phenolic resin, It is at least one of polymethyl methacrylate or a mixture thereof.

Preferably, in step (1), the solvent is any one of water solvent, alcohol solvent, ether solvent, lipid solvent, and alkane solvent.

More preferably, the alcohol solvent is at least one of methanol, ethanol, isopropanol, and butanol, or a mixture thereof. The ether solvent is ethyl ether. The lipid solvent is at least one of ethyl acetate, butyl acetate, and amyl acetate, or a mixture thereof. The alkane solvent is at least one of n-hexane, cyclohexane, pine oil, kerosene, and n-heptane, or a mixture thereof.

Preferably in step (1), the product is suspended in the mixture, and before entering step (2), the product is separated from the mixture by filtration.

Preferably, in step (2), the metal powder coated with the polymer material is fired to harden the polymer material on the surface of the metal powder.

More preferably, the calcination temperature is 140°C to 200°C.

Preferably, in step (2), metal powder having a particle size D90 ranging from 50 ㎛ to 150 ㎛ is obtained.

In order to achieve the above-mentioned object, the technical solution adopted in the present invention is metal powder coated with polymer material. The metal powder is manufactured by any of the above-described manufacturing methods.

In order to achieve the above-described object, the technical solution adopted in the present invention is to apply metal powder coated with the above-described polymer material to a metal injection molding process (Metal Injection Molding, MIM).

To achieve the above-mentioned object, the technical solution adopted in the present invention is a method of manufacturing metal parts using metal powder coated with the above-described polymer material, which includes the following steps.

(a) The metal powder and polymer material are mixed and granulated.

(b) Perform metal injection molding on the particles obtained in step (a) to obtain a primary product.

(c) Perform catalytic degreasing on the primary product obtained in step (b) to obtain an intermediate product.

(d) The intermediate product obtained in step (c) is sintered to obtain a metal part.

Preferably in step (a), the polymer material is one of polyoxymethylene and wax or a mixture thereof.

Preferably in step (c), the medium used for degreasing is nitric acid or oxalic acid, the degreasing temperature is 100°C to 145°C, and the degreasing acid injection time is 4 to 6 hours.

By applying the above-described technical solution, the present invention has the following advantages over the prior art.

1. The method for manufacturing a metal powder coated with a polymer material provided by the present invention has the defect of not being able to completely remove the oxide film from the current technology for removing the oxide film on the surface of the metal powder using a chemical reaction method or independent mechanical and mechanical polishing. overcome. The use of deoxidation film solutions can cause a chemical reaction on the metal powder surface to remove oxide films on concave surfaces within metal powder particles or on surfaces that cannot be contacted by physical mechanical polishing. Additionally, thick oxide films can be removed on a large scale using physical methods. Completely and effectively removes the oxide film on the surface of metal powder through two double guarantees.

2. The method for producing a metal powder coated with a polymer material provided by the present invention isolates oxygen by coating the polymer material on the surface of the metal powder from which the oxide film has been removed, thereby effectively preventing the regeneration of the oxide film on the surface of the metal powder.

3. In the metal powder coated with the polymer material provided in the present invention, the oxide film on the surface of the metal powder is removed and coated with the polymer material. Therefore, the metal powder can be applied to the metal injection molding process to increase the application area of the metal material.

4. In the method of manufacturing metal parts using metal powder coated with a polymer material provided by the present invention, the oxide film is removed and the metal powder coated with the polymer material is kneaded and assembled. Additionally, the obtained particles are injection molded according to the metal injection molding (MIM) process, and then degreasing and sintering are performed to obtain metal parts. Through this, metal parts with complex structures, small sizes, and high density can be produced, which has excellent economic efficiency and broad application prospects.

1 is a process flow diagram of a method for producing metal powder coated with a polymer material according to the present invention.
Figure 2 is a process flow diagram of a method for manufacturing metal parts using metal powder coated with a polymer material according to the present invention.

Hereinafter, relatively preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily understand the advantages and characteristics of the present invention, and protect the present invention. Define the scope more clearly.

As shown in Figure 1, the present invention provides a method for producing metal powder coated with a polymer material, which includes the following steps.

1. Mix metal powder coated with an oxide film on the surface, a deoxidation film solution, a polymer material, and a solvent for dissolving the polymer material and place them in an airtight container. Place the sealed container on the ball mill and turn on the power to adjust the rotation speed. The sealed container is rotated on a ball mill to create friction between the metal powders to physically remove the oxide film coated on the surface of the metal powder. During the mixing process, the deoxidation film solution causes a chemical reaction with the oxide film to chemically remove the oxide film to obtain a mixture. The product of the above-mentioned chemical reaction is suspended in the mixture, and after the mixture is left to stand, the suspension in the mixture is removed by filtration to obtain a mixture containing the metal powder from which the oxide film has been removed and the solvent in which the polymer material is dissolved. The order of the process of removing the oxide film described above and the process of physically removing the oxide film does not affect the final result.

2. Dry the metal powder in the mixture from which the suspension has been removed, and volatilize the solvent on the metal powder using a dryer or heated spray dryer. Through this, the remaining polymer material is coated on the surface of the metal powder to obtain a metal powder coated with the polymer material.

In Step 1, the material of the metal powder coated with an oxide film on the surface is at least one of aluminum, aluminum alloy, magnesium, magnesium alloy, titanium, titanium alloy, copper, and copper alloy. If it is an aluminum alloy, it is preferably an aluminum-magnesium-based alloy or an aluminum-magnesium-silicon-based alloy.

In step 1, the deoxidation film solution may be an acidic solution or an alkaline solution. If this is an acidic solution, it can be strong acids such as sulfuric acid, hydrochloric acid, nitric acid and iodic acid, medium strong acids such as oxalic acid, sulfurous acid, phosphoric acid, pyruvic acid and nitrous acid, citric acid, hydrofluoric acid, malic acid, gluconic acid, formic acid, lactic acid, It may be a weak acid such as benzoic acid, acrylic acid, acetic acid, propionic acid, stearic acid, carbonic acid, hydrosulfate acid, ammonium bifluoride, hydrogen peroxide, hypochlorous acid, phenol, phosphoric acid, boric acid, and silicic acid. Considering the reaction rate, phosphoric acid, boric acid and silicic acid in weak acids are preferred. If this is an alkaline solution, the alkali may be a strong alkali such as potassium hydroxide and sodium hydroxide.

When selecting an oxide film removal solution, it should be selected according to the characteristics of the oxide film coated with metal powder. For example, magnesium oxide generally uses hydrofluoric acid and ammonium bifluoride, titanium oxide generally uses nitric acid, hydrofluoric acid, and hydrogen peroxide, and aluminum oxide generally uses hydrochloric acid, nitric acid, sodium hydroxide, phosphoric acid, and boric acid. And for copper oxide, dilute sulfuric acid, dilute hydrochloric acid, and acetic acid are generally used.

The polymeric material of Stage 1 includes thermoset plastic or thermoset plastic. When used, polymer materials are dissolved in corresponding solvents. Solvents in step 1 include water solvents, alcohol-based solvents, ether-based solvents, lipid-based solvents, and alkane-based solvents. Preferred solvents are alcohol-based solvents, ester-based solvents, and alkane-based solvents. The alcohol solvent is preferably methanol, ethanol, isopropanol, and butanol, the ether solvent is preferably ethyl ether, the lipid solvent is preferably ethyl acetate, butyl acetate and amyl acetate, and the alkane solvent is preferably are n-hexane, cyclohexane, pine oil, kerosene and n-heptane. When the solvent in step 1 is a water solvent, the polymer material in step 1 is a thermosetting plastic or thermoplastic, such as polyvinyl alcohol, polyethylene glycol, polyoxyethylene, polyacrylic acid, sodium polyacrylate, polyvinylpyrrolidone, There are propylene glycol, diethylene glycol, triethylene glycol, polypropylene glycol, and triethanolamine. When the solvent in Step 1 is alcohol, the polymer material in Step 1 may be a phenol resin or polymethyl methacrylate. Considering the toxicity, functionality, suitability, and operability of the solvent, the solvent in Step 1 is preferably ethanol, and the polymer material in Step 1 is preferably phenol resin or polymethyl methacrylate.

Preferably, in step 2, the metal powder coated with the polymer material is fired to harden the polymer material on the surface of the metal powder. The firing temperature is 140°C to 200°C.

Preferably, the particle size D90 of the metal powder obtained in step 2 is distributed between 50㎛ and 150㎛.

The present invention further provides a metal powder coated with a polymer material. The metal powder is manufactured according to any of the manufacturing methods described above, and the metal powder can be applied to a metal injection molding process.

As shown in Figure 2, the present invention further provides a method of manufacturing a metal part using the metal powder described above, which includes the following steps.

(a) The metal powder and polymer material are mixed and assembled.

(b) Perform metal injection molding on the particles obtained in step (a) to obtain a primary product.

(c) Degreasing is performed on the primary product obtained in step (b) to obtain an intermediate product.

(d) The intermediate product obtained in step (c) is sintered to obtain a metal part.

Preferably, the polymeric material in step (a) is polyoxymethylene (POM) or wax (WAX).

Preferably, the volume ratio of the metal powder and the polymer material in step (a) is 1:0.8 to 1.3.

Preferably, the kneading in step (a) is performed in a closed kneading method, the kneading temperature is 150°C to 190°C, and the kneading time is 1 hour to 1.5 hours.

Preferably, the particles formed in step (a) are cylindrical, with a diameter of 2.5 mm to 3.5 mm and a length of 3 mm to 5 mm.

Preferably, the temperature of the injection nozzle during metal injection molding in step (b) is 180°C to 210°C, and the molding pressure is 95Mpa to 105Mpa.

Preferably in step (c), the medium used for degreasing is nitric acid or oxalic acid, the degreasing temperature is 100°C to 145°C, and the degreasing acid injection time is 4 to 6 hours.

Preferably, in step (d), the sintering temperature is 550°C to 1250°C, the sintering time is 2 hours to 3 hours, and the sintering temperature matches different temperature ranges depending on the material.

In order to better explain the present invention and to facilitate a better understanding of the technical solutions of the present invention, exemplary but non-limiting embodiments of the present invention are described as follows.

Example 1 is as shown in Figure 1.

(1) Mix 100 g of aluminum-magnesium-silicon alloy powder (6xxx series aluminum alloy), 0.1 g of phosphoric acid, 2 g of phenol resin, and 1000 ml of ethanol solvent and place them in a ball mill. The mixture is obtained by performing ball milling for 2 hours. The surface suspension in the mixture is removed to obtain aluminum alloy powder coated with phenolic resin.

(2) The above-described aluminum alloy powder is heated using a granulator to evaporate the solvent, or the solvent is evaporated through spray drying to obtain a lump-shaped aluminum alloy powder coated with a phenol resin. The particle size D90 in the aluminum alloy powder is distributed between 50 μm and 150 μm. The above-described aluminum alloy powder is placed in an environment at 140°C and fired to harden the particle surface. Through this, aluminum alloy powder completely coated with phenolic resin is obtained.

The above-described aluminum alloy powder is applied to an injection molding (MIM) process to fabricate aluminum alloy parts, which includes the following steps.

(a) Mix the above-mentioned aluminum alloy powder and polyoxymethylene (POM) at a volume ratio of 1:1. This is heated to 170°C in a closed kneader and kneaded for 1 hour, then transferred to a granulator to produce cylindrical particles with a particle diameter of 3 mm and a length of 3 mm to 5 mm.

(b) The cylindrical particles obtained in step (a) are placed into the molding machine material pipe through an injection nozzle at a temperature of 200°C, and injection molding is performed under a molding pressure of 100Mpa to obtain a green body of the required shape.

(c) The raw material obtained in step (b) is transferred to a catalytic degreasing furnace and acid injection degreasing is performed for 4.5 hours using nitric acid as a medium in an environment of 100°C to 120°C.

(d) The degreased product is sintered at 600°C for 2.5 hours to obtain a finished aluminum-magnesium-silicon alloy sintered product with a high density of 2.75 g/cm3.

Example 2:

(1) Mix 100 g of aluminum-magnesium-silicon alloy powder (6xxx series aluminum alloy), 0.5 g of boric acid, 2 g of phenol resin, and 1000 ml of ethanol solvent and place them in a ball mill. The mixture is obtained by performing ball milling for 2 hours. The surface suspension in the mixture is removed to obtain aluminum alloy powder coated with phenolic resin.

(2) Using a granulator, heat the above-described aluminum alloy powder to evaporate the solvent, or evaporate the solvent through spray drying to obtain a lump-shaped aluminum alloy powder coated with a phenol resin. The particle size D90 in the aluminum alloy powder is distributed between 50 μm and 150 μm. The above-described aluminum alloy powder is placed in an environment at 140°C and fired to harden the particle surface. Through this, aluminum alloy powder completely coated with phenolic resin is obtained.

The above-described aluminum alloy powder is applied to an injection molding (MIM) process to fabricate aluminum alloy parts, which includes the following steps.

(a) Mix the above-mentioned aluminum alloy powder and polyoxymethylene (POM) at a volume ratio of 1:1. This is heated to 170°C in a closed kneader and kneaded for 1 hour, then transferred to a granulator to produce cylindrical particles with a particle diameter of 3 mm and a length of 3 mm to 5 mm.

(b) The cylindrical particles obtained in step (a) are placed into the molding machine material pipe through an injection nozzle at a temperature of 200°C, and injection molding is performed under a molding pressure of 100Mpa to obtain a green body of the required shape.

(c) The raw material obtained in step (b) is transferred to a catalytic degreasing furnace and acid injection degreasing is performed for 4.5 hours using nitric acid as a medium in an environment of 100°C to 120°C.

(d) The degreased product is sintered at 600°C for 2.5 hours to obtain a finished aluminum-magnesium-silicon alloy sintered product with a high density of 2.76 g/cm3.

Example 3:

(1) Mix 100 g of aluminum-magnesium-silicon alloy powder (6xxx series aluminum alloy), 0.6 g of silicic acid, 2 g of phenol resin, and 1000 ml of ethanol solvent and place them in a ball mill. The mixture is obtained by performing ball milling for 2 hours. The surface suspension in the mixture is removed to obtain aluminum alloy powder coated with phenolic resin.

(2) Using a granulator, heat the above-described aluminum alloy powder to evaporate the solvent, or evaporate the solvent through spray drying to obtain a lump-shaped aluminum alloy powder coated with a phenol resin. The particle size D90 in the aluminum alloy powder is distributed between 50 μm and 150 μm. The above-described aluminum alloy powder is placed in an environment at 140°C and fired to harden the particle surface. Through this, aluminum alloy powder completely coated with phenolic resin is obtained.

The above-described aluminum alloy powder is applied to an injection molding (MIM) process to fabricate aluminum alloy parts, which includes the following steps.

(a) Mix the above-mentioned aluminum alloy powder and polyoxymethylene (POM) at a volume ratio of 1:1. This is heated to 170°C in a closed kneader and kneaded for 1 hour, then transferred to a granulator to produce cylindrical particles with a particle diameter of 3 mm and a length of 3 mm to 5 mm.

(b) The cylindrical particles obtained in step (a) are placed into the molding machine material pipe through an injection nozzle at a temperature of 200°C, and injection molding is performed under a molding pressure of 100Mpa to obtain a green body of the required shape.

(c) The raw material obtained in step (b) is transferred to a catalytic degreasing furnace and acid injection degreasing is performed for 4.5 hours using nitric acid as a medium in an environment of 100°C to 120°C.

(d) The degreased product is sintered at 600°C for 2.5 hours to obtain a finished aluminum-magnesium-silicon alloy sintered product with a high density of 2.74 g/cm3.

The above-described embodiments are intended to explain the technical idea and features of the present invention, and are intended to enable those skilled in the art to understand the contents of the present invention and practice it accordingly, thereby expanding the scope of protection of the present invention. No restrictions. All equivalent changes or modifications made substantially based on the spirit of the present invention are included within the protection scope of the present invention.

Claims (23)

A method for producing metal powder coated with a polymer material, comprising:
(1) Mixing a metal powder coated with an oxide film on the surface, a deoxidation film solution, a polymer material, and a solvent for dissolving the polymer material - During the mixing process, the deoxidation film solution causes a chemical reaction with the oxide film to form the oxide film. Chemically removing to obtain a mixture, wherein the mixture includes at least a metal powder from which the oxide film has been removed or partially removed, a polymer material dissolved by the solvent, the deoxidation film solution, and a product after a chemical reaction of the oxide film; and
(2) A method for producing a metal powder coated with a polymer material, comprising the step of drying the metal powder in the mixture and volatilizing the solvent on the metal powder to obtain a metal powder coated with the polymer material. According to paragraph 1,
In step (1), the mixture is a polymer material characterized in that the oxide film coated on the surface of the metal powder is physically removed by generating mutual friction between the metal powders through at least one of polishing, vibration, and stirring. Method for producing coated metal powder. According to paragraph 1,
In step (1), the material of the metal powder coated with an oxide film on the surface is at least one of aluminum, aluminum alloy, magnesium, magnesium alloy, titanium, titanium alloy, copper, and copper alloy. Method for producing metal powder. According to paragraph 3,
A method of producing a metal powder coated with a polymer material, wherein the aluminum alloy is an aluminum-magnesium alloy or an aluminum-magnesium-silicon alloy. According to paragraph 1,
In step (1), the method of producing a metal powder coated with a polymer material, characterized in that the deoxidation film solution is an acidic solution. According to clause 5,
The acidic solution is a solution containing a strong acid, and the strong acid is at least one of sulfuric acid, hydrochloric acid, nitric acid, and iodic acid, or a mixture thereof. According to clause 5,
The acidic solution is a solution containing a medium strong acid, and the medium strong acid is at least one of oxalic acid, sulfurous acid, phosphoric acid, pyruvic acid, and nitrous acid, or a mixture thereof. According to clause 5,
The acidic solution is a solution containing a weak acid, and the weak acids include citric acid, hydrofluoric acid, malic acid, gluconic acid, formic acid, lactic acid, benzoic acid, acrylic acid, acetic acid, propionic acid, stearic acid, carbonic acid, hydrosulfate, hypochlorous acid, phenol, and phosphoric acid. , A method for producing a metal powder coated with a polymer material, characterized in that it is at least one of boric acid and silicic acid, or a mixture thereof. According to paragraph 1,
In step (1), the method of producing a metal powder coated with a polymer material, characterized in that the deoxidation film solution is an alkaline solution. According to clause 9,
The alkaline solution is a solution containing an alkali, and the alkali is any one of sodium hydroxide and potassium hydroxide or a mixture thereof. According to paragraph 1,
In step (1), the polymer material is one of thermoset plastic, thermoplastic plastic, or a mixture thereof. According to clause 11,
The polymer materials include polyvinyl alcohol, polyethylene glycol, polyoxyethylene, polyacrylic acid, sodium polyacrylate, polyvinylpyrrolidone, propylene glycol, diethylene glycol, triethylene glycol, polypropylene glycol, triethanolamine, phenol resin, poly A method of producing a metal powder coated with a polymer material, characterized in that it is at least one of methyl methacrylate or a mixture thereof. According to paragraph 1,
In step (1), the solvent is any one of a water solvent, an alcohol solvent, an ether solvent, a lipid solvent, and an alkane solvent. According to clause 13,
The alcohol solvent is at least one of methanol, ethanol, isopropanol, and butanol, or a mixture thereof, the ether solvent is ethyl ether, and the lipid solvent is at least one of ethyl acetate, butyl acetate, and amyl acetate, or a mixture thereof. and the alkane solvent is at least one of n-hexane, cyclohexane, pine oil, kerosene, and n-heptane, or a mixture thereof. According to paragraph 1,
In step (1), the product is suspended in the mixture, and before entering step (2), the product is separated from the mixture by filtration. According to paragraph 1,
In step (2), a method for producing a metal powder coated with a polymer material, characterized in that the metal powder coated with the polymer material is fired to harden the polymer material on the surface of the metal powder. According to clause 16,
A method of producing a metal powder coated with a polymer material, characterized in that the sintering temperature is 140°C to 200°C. According to paragraph 1,
In step (2), a method for producing a metal powder coated with a polymer material, characterized in that obtaining a metal powder having a particle size D90 distributed between 50 ㎛ and 150 ㎛. A metal powder coated with a polymer material,
A metal powder coated with a polymer material, characterized in that the metal powder is manufactured by the method for producing a metal powder coated with a polymer material according to any one of claims 1 to 18. Application of a metal powder coated with a polymer material according to claim 19, comprising:
Application of a metal powder coated with a polymer material, characterized in that the metal powder is applied to a metal injection molding process. A method for manufacturing metal parts, comprising:
The metal part is manufactured from metal powder, wherein the metal powder is manufactured by the manufacturing method according to any one of claims 1 to 18, including:
(a) mixing and assembling the metal powder and polymer material;
(b) performing metal injection molding on the particles obtained in step (a) to obtain a primary product;
(c) performing catalytic degreasing on the primary product obtained in step (b) to obtain an intermediate product; and
(d) sintering the intermediate product obtained in step (c) to obtain a metal part. According to clause 21,
In step (a), the polymer material is one of polyoxymethylene and wax or a mixture thereof. According to clause 21,
In step (c), the medium used for degreasing is nitric acid or oxalic acid, the degreasing temperature is 100°C to 145°C, and the degreasing acid injection time is 4 to 6 hours.