A method for additive manufacturing of highly brittle colored gold

Abstract

The present invention discloses an additive manufacturing molding method for high-brittle color gold, firstly, the precious metal monomer powder is dispersed with a photosensitive resin, an anti-settling agent and a dispersant to form a stable suspension; the suspension is placed in a DLP type sinking 3D printer, and a green embryo light-curing additive manufacturing is performed to form a green embryo; the green embryo is placed in an atmosphere heat treatment furnace, and argon gas is introduced for degreasing to remove organic matter in the green embryo; the green embryo after degreasing is continuously heated to an alloying temperature point, and an alloying heat treatment is performed; the alloyed green embryo is continuously heated to a sintering temperature, argon gas is introduced and cooled to below 300°C, and the green embryo is taken out and cooled in the air to obtain a finished product. The molding method in the present invention has the advantages of simple molding process and no mold is required, no separate alloying process is required, low heat treatment temperature, avoiding alloy component segregation, high compatibility of powder material with manufacturing process, low material loss, and reusable residual raw materials, etc., and is suitable for materials that are inherently brittle and difficult to process in traditional ways.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing and powder metallurgy, and more specifically to an additive manufacturing molding method for high-brittle colored gold. Background Art

[0002] Generally, the hardness of materials suitable for machining by subtractive manufacturing is about 25-30HRC, and it is difficult to machine when it exceeds 45HRC. The hardness and brittleness of precious metal materials will increase significantly after forming alloys with other metal elements, and the alloying process needs to be isolated from oxygen. Therefore, some precious metal alloys, such as purple and pink gold, often do not have machinability. Although the above two kinds of gold are bright in color, traditional subtractive manufacturing technologies such as turning, milling, planing, and grinding cannot be directly applied; at the same time, factors such as anaerobic casting and component segregation during cooling of complex alloy structures make melting and casting technology impossible to apply, so the material can only be used for inlay. In traditional additive manufacturing methods, refractory metals generally require a very high power density laser beam or electron beam to melt or sinter the metal powder in order to achieve 3D printing. For refractory precious metal alloys with high melting point, strong light reflectivity, and high thermal conductivity, it is even more difficult to achieve 3D printing. Summary of the invention

[0003] The embodiment of the present invention provides an additive manufacturing molding method for high-brittleness colored gold, which is suitable for the molding of high-hardness, high-brittleness refractory precious metal alloy materials. It combines the alloying and molding processes of precious metal alloy materials, solves the harsh conditions of anaerobic molding required during high-temperature melting and casting, and solves the problem of component segregation caused by the process, thereby ensuring uniform product composition and stable performance.

[0004] The embodiment of the present invention provides an additive manufacturing method for high-brittle colored gold, comprising the following steps:

[0005] (1) mixing powder 1 and powder 2 for preparing a precious metal alloy in a uniform proportion, placing the mixture in a ball mill, adding ethanol and stearic acid to modify the mixed powder to be hydrophobic, and taking out the modified mixed powder for drying and standby use, wherein the ethanol liquid level just covers the grinding balls and the mixed powder;

[0006] (2) mixing a photosensitive resin, an anti-settling agent and a dispersant in a mass ratio of 60-96:2-20:2-20 to form an organic solution, and mixing the modified and dried mixed powder with the organic solution to form a stable suspension;

[0007] (3) placing the suspension in a DLP type sink-type 3D printer to perform green body light curing additive manufacturing to form a green body;

[0008] (4) placing the green body in an atmosphere heat treatment furnace, introducing argon gas at 200-500° C. for degreasing to remove organic matter in the green body;

[0009] (5) The degreased green body is further heated to a solid phase reaction alloying temperature of 700-800° C. for alloying heat treatment;

[0010] (6) The alloyed green body is further heated to the sintering temperature, and argon gas is introduced to cool it to below 300°C, and then it is taken out and cooled in air to obtain a finished product.

[0011] Preferably, in step (1), powder 1 is gold, powder 2 is one or both of aluminum or copper, the mass ratio of powder 1 to powder 2 is 1-6:9-11, the median diameter D50 of powder 1 and powder 2 is 5-50 μm, the morphology is spherical powder, the ball-to-material ratio in the ball mill is 10:1, the mass ratio of the mixed powder to stearic acid is 5:100, the ball mill speed is 600 r / min, the ball mill time is 80 min, and the drying temperature is 50-70 ° C.

[0012] Preferably, in step (2), the volume ratio of the mixed powder to the organic solution is 4-9:6-1, the photosensitive resin is composed of trimethylolpropane triacrylate, 1,6-hexanediol diacrylate and TPO (diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide), wherein the mass ratio of trimethylolpropane triacrylate to 1,6-hexanediol diacrylate is 8:1, the mass of TPO is 0.5-5% of the mass of the mixture of trimethylolpropane triacrylate and 1,6-hexanediol diacrylate, and the dispersion time is 2-12h.

[0013] Preferably, in step (2), the anti-settling agent is selected from one of the series of modified polyurea N-methylpyrrolidone solution (BYK-410), modified hydrogenated castor oil, titanate coupling agent, and polyamide wax.

[0014] Preferably, in step (2), the dispersant is one of acrylic block copolymers.

[0015] Preferably, in step (3), the number of bottom layers of the green embryo light-curing additive manufacturing is 6 layers, the exposure time is 6-30 seconds / layer, the normal exposure time is 3-12 seconds / layer, and the curing depth is 15-50 μm / layer.

[0016] Preferably, in step (5), the alloying heat treatment temperature is 65% of the alloy melting point, and the holding time is 30-60 minutes.

[0017] Preferably, in step (6), the sintering temperature is 80% of the melting point of the alloy, the temperature is kept for 3 hours, and the argon cooling gas flow rate is 15-45 ml / min.

[0018] In the embodiment of the present invention, a method for additive manufacturing of high-brittle color gold is provided, which can solve the problem of high brittleness and high melting point of precious metal alloys that are difficult to process and form. The forming process is simple and does not require a mold, does not require a separate alloying process, has a low heat treatment temperature, avoids alloy component segregation, has high compatibility between powder materials and manufacturing processes, has low material loss, and the remaining raw materials can be reused. The method can be used to manufacture products with complex structures, and the production efficiency is only related to the size of the 3D printer model, and has nothing to do with the complexity of the structure. The obtained product has high hardness and high temperature resistance, and combined with the bright color characteristics of precious metal alloys, it can be widely used in the industrial field and the jewelry field. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Example 1

[0021] Embodiment 1 of the present invention provides an additive manufacturing method for high-brittle colored gold, comprising the following steps:

[0022] (1) Spherical gold powder and spherical aluminum powder for preparing precious metal alloy are mixed uniformly in a mass ratio of 4:9, and the particle sizes of the gold powder and the aluminum powder both meet the D50 of 15 μm. The powder is placed in a ball mill, the grinding balls are made of polytetrafluoroethylene balls, the ball-to-material ratio is 10:1, the ball mill speed is 600 r / min, and the ball milling time is 80 min. Ethanol and stearic acid are added to modify the hydrophobicity of the mixed powder, and the modified mixed powder is taken out and dried for use, wherein the ethanol liquid level just covers the grinding balls and the mixed powder, the mass ratio of the mixed powder to the stearic acid is 5:100, and the drying temperature is 50°C.

[0023] (2) A photosensitive resin, an anti-settling agent and a dispersant are mixed uniformly in a mass ratio of 60:2:2 to form an organic solution, wherein the photosensitive resin is composed of trimethylolpropane triacrylate, 1,6-hexanediol diacrylate and TPO (diphenyl-(2,4,6-trimethylbenzoyl)phosphine), the mass ratio of trimethylolpropane triacrylate to 1,6-hexanediol diacrylate is 8:1, the mass of TPO is 0.5% of the mass of the mixture of trimethylolpropane triacrylate and 1,6-hexanediol diacrylate, the anti-settling agent is a modified polyurea N-methylpyrrolidone solution (BYK-410), and the dispersant is an acrylic block copolymer. The modified and dried mixed powder and the organic solution are mixed and stirred uniformly in a volume ratio of 7:3 to form a stable suspension, and the dispersion time is 12 hours.

[0024] (3) placing the suspension in a DLP type sink-type 3D printer to perform green body photocuring additive manufacturing to form a green body; wherein the number of bottom layers of the green body photocuring additive manufacturing is 6 layers, the exposure time is 12 seconds / layer, the normal exposure time is 6 seconds / layer, and the curing depth is 50 μm / layer

[0025] (4) The green body is placed in an atmosphere heat treatment furnace and argon gas is introduced to perform degreasing at 200°C to remove organic matter in the green body.

[0026] (5) The degreased green body is further heated to an alloying temperature of 700°C and kept at that temperature for 30 minutes for alloying heat treatment.

[0027] (6) The alloyed green body is further heated to a sintering temperature of 720° C., kept at this temperature for 3 h, and then cooled to below 300° C. by introducing argon gas, and then cooled in air to obtain a finished product, wherein the argon cooling gas flow rate is 30 ml / min.

[0028] The finished product of purple gold (Au6Al 11 ) has a density of about 9.66 g / cm3, which is about 92% of the theoretical density of the alloy after densification. The gold content is about 79.92 wt%, and the overall color is uniform purple, indicating that alloying has been completed.

[0029] Example 2

[0030] Embodiment 2 of the present invention provides an additive manufacturing method for high-brittle colored gold, comprising the following steps:

[0031] (1) Spherical gold powder, aluminum powder and copper powder for preparing precious metal alloy are mixed uniformly in a mass ratio of 1:5:6, and the particle size D50 of the gold powder, aluminum powder and copper powder are all 50 μm. The powders are placed in a ball mill, the grinding balls are made of polytetrafluoroethylene balls, the ball-to-material ratio is 10:1, the ball mill speed is 600 r / min, and the ball milling time is 80 min. Ethanol and stearic acid are added to modify the hydrophobicity of the mixed powder, and the modified mixed powder is taken out and dried for use, wherein the ethanol liquid level just covers the grinding balls and the mixed powder, the mass ratio of the mixed powder to the stearic acid is 5:100, and the drying temperature is 70°C.

[0032] (2) A photosensitive resin, an anti-settling agent and a dispersant are mixed uniformly in a mass ratio of 90:18:20 to form an organic solution, wherein the photosensitive resin is composed of trimethylolpropane triacrylate, 1,6-hexanediol diacrylate and TPO (diphenyl-(2,4,6-trimethylbenzoyl)phosphine), the mass ratio of trimethylolpropane triacrylate to 1,6-hexanediol diacrylate is 8:1, the mass of TPO is 1% of the mass of the mixture of trimethylolpropane triacrylate and 1,6-hexanediol diacrylate, the anti-settling agent is a modified polyurea N-methylpyrrolidone solution (BYK-410), and the dispersant is an acrylic block copolymer. The modified and dried mixed powder and the organic solution are mixed and stirred uniformly in a volume ratio of 9:1 to form a stable suspension, and the dispersion time is 2 hours.

[0033] (3) placing the suspension in a DLP type sink-type 3D printer to perform green body photocuring additive manufacturing to form a green body; wherein the number of bottom layers of the green body photocuring additive manufacturing is 6 layers, the exposure time is 12 seconds / layer, the normal exposure time is 5 seconds / layer, and the curing depth is 30 μm / layer

[0034] (4) The green body is placed in an atmosphere heat treatment furnace and argon gas is introduced to perform degreasing at 500°C to remove organic matter in the green body.

[0035] (5) The degreased green body is further heated to 700°C solid phase reaction alloying temperature and kept at this temperature for 30 minutes for alloying heat treatment.

[0036] (6) The alloyed green body is further heated to a sintering temperature of 880° C., kept at this temperature for 3 h, and then cooled to below 300° C. by introducing argon gas, and then cooled in air to obtain a finished product, wherein the argon cooling gas flow rate is 30 ml / min.

[0037] The density of the finished gold-aluminum-copper ternary alloy obtained by additive manufacturing is about 9.53g / cm3, and the overall color is uniform pink, indicating that alloying has been completed.

[0038] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0039] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. An additive manufacturing method for high-brittle color gold, characterized in that: The following steps are involved: (1) mixing powder 1 and powder 2 for preparing a precious metal alloy in a uniform proportion, placing the mixture in a ball mill, adding ethanol and stearic acid, modifying the mixed powder to be hydrophobic, and taking out the modified mixed powder for drying and standby use, wherein the ethanol liquid level just covers the grinding balls and the mixed powder, wherein the powder 1 is selected from gold, and the powder 2 is selected from one or both of aluminum and copper; (2) mixing a photosensitive resin, an anti-settling agent and a dispersant in a mass ratio of (60-96):(2-20):(2-20) to form an organic solution, mixing the modified and dried mixed powder with the organic solution, stirring and dispersing them to form a stable suspension, wherein the photosensitive resin is composed of trimethylolpropane triacrylate, 1,6-hexanediol diacrylate and TPO (diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide), and the dispersant is selected from one of acrylic block copolymers; (3) placing the suspension in a DLP type sink-type 3D printer to perform green body light curing additive manufacturing to form a green body; (4) placing the green body in an atmosphere heat treatment furnace, introducing argon gas at 200-500° C. for degreasing to remove organic matter in the green body; (5) The degreased green body is further heated to a solid phase reaction alloying temperature of 700-800° C. for alloying heat treatment; (6) The alloyed green body is further heated to the sintering temperature, and argon gas is introduced to cool it to below 300°C, and then it is taken out and cooled in air to obtain a finished product.

2. The additive manufacturing method for high-brittle colored gold according to claim 1, characterized in that: In step (1), the mass ratio of powder one to powder two is (1-6):(9-11), the median diameter D50 of powder one and powder two is 5-50 μm, the morphology is spherical powder, the ball-to-material ratio in the ball mill is 10:1, the mass ratio of the mixed powder to the stearic acid is 5:100, the ball mill speed is 600 r / min, the ball milling time is 80 min, and the drying temperature is 50-70 ° C.

3. The additive manufacturing method for high-brittle colored gold according to claim 1, characterized in that: In step (2), the volume ratio of the mixed powder to the organic solution is (4-9):(6-1), wherein the mass ratio of trimethylolpropane triacrylate to 1,6-hexanediol diacrylate is 8:1, the mass of TPO is 0.5-5% of the mass of the mixture of trimethylolpropane triacrylate and 1,6-hexanediol diacrylate, and the dispersion time is 2-12 hours.

4. The additive manufacturing method for high-brittle colored gold according to claim 1, characterized in that: In step (2), the anti-settling agent is selected from one of the series of modified polyurea N-methylpyrrolidone solution (BYK-410), modified hydrogenated castor oil, titanate coupling agent, and polyamide wax.

5. The additive manufacturing method for high-brittle colored gold according to claim 1, characterized in that: In step (3), the number of bottom layers of the green embryo light-curing additive manufacturing is 6 layers, the exposure time is 6-30 seconds / layer, the normal exposure time is 3-12 seconds / layer, and the curing depth is 15-50 μm / layer.

6. The additive manufacturing method for high-brittle colored gold according to claim 1, characterized in that: In step (5), the alloying heat treatment temperature is 65% of the alloy melting point, and the holding time is 30-60 minutes.

7. The additive manufacturing method for high-brittle colored gold according to claim 1, characterized in that: In step (6), the sintering temperature is 80% of the melting point of the alloy, the temperature is kept for 3 hours, and the argon cooling gas flow rate is 15-45 ml / min.