Method for manufacturing metal copper special-shaped parts by photocuring indirect additive manufacturing and metal copper special-shaped parts

Abstract

The present invention relates to the technical field of metal additive manufacturing, and provides a method for photocuring indirect additive manufacturing of metal copper special-shaped parts and metal copper special-shaped parts. The method comprises: preparing a photocuring slurry, photocuring additive manufacturing, and heat treatment. The present invention does not require a high-energy laser beam to melt copper powder, and can produce metal copper components with uniform structure and excellent performance. The equipment used is lower in cost than other additive manufacturing processes and has the ability to be mass-produced. During the degreasing stage, no decomposition and release of gas is performed, and combined with a two-step degreasing method, the introduction of cracks and pores can be completely avoided. The present invention uses copper oxide as a precursor, which reduces the density of pure copper powder by nearly 30%, and the resulting photosensitive slurry can remain stable for a long time without settling.

Description

Technical Field

[0001] The present invention relates to the technical field of metal additive manufacturing, and in particular to a method for indirectly manufacturing a metal copper special-shaped part using photocuring additive manufacturing, and the metal copper special-shaped part. Background Art

[0002] Copper, a metal material with excellent thermal and electrical conductivity, plays a vital role in various industrial applications. Traditionally, copper processing involves melting in air and then casting. This is a relatively low-cost and mature process. However, with the miniaturization, intensification, and high-power development of functional devices, the demand for complex copper components is increasing, making traditional processing methods difficult to meet.

[0003] Metal additive manufacturing technology represented by laser additive manufacturing technology has brought a new way to prepare special-shaped metal copper components. However, laser additive manufacturing technology for metal copper faces many problems. First, metal copper is a high-reflectivity material. Most mainstream additive manufacturing equipment uses lasers with a wavelength of 1064nm. Copper's reflectivity to lasers with this wavelength reaches 95%, so it cannot absorb enough energy, resulting in insufficient melting, aggravated porosity and spheroidization, poor performance, and the emitted laser will also damage the optical system of the equipment; second, the prices of laser additive manufacturing equipment and special powders are relatively high, and even need to be customized, which greatly limits the application.

[0004] Therefore, a suitable additive manufacturing method for copper metal is extremely necessary. For example, patent CN 113695567 A discloses a method for selective laser sintering printing of coated copper alloys and their preparation and sintering. A binder is chemically grafted onto the powder surface, and then selective laser sintering is used to form complex copper metal components. Patent CN 115740486 A discloses a photocurable printed carbide tool and its preparation method, involving a preparation method of directly mixing copper metal powder with a photosensitive resin using photocurable molding.

[0005] However, processes like selective laser sintering and adhesive jetting suffer from poor precision, making them inadequate for producing precision copper components. While photocuring offers higher precision, copper's high density inevitably leads to sedimentation in the slurry, resulting in printing failures. Using copper powder directly as a raw material, oxygen-containing organic matter reacts with copper during the degreasing process, resulting in a high oxygen content in the copper and affecting final performance. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a method for indirect additive manufacturing of metal copper special-shaped parts by photocuring and a metal copper special-shaped part. Nano-copper oxide / cuprous oxide with low density is used as a precursor, combined with photocuring preparation technology to obtain metal copper three-dimensional special-shaped components with high precision, high density and excellent performance.

[0007] The present invention adopts the following scheme:

[0008] In one aspect, the present invention provides a method for indirectly additively manufacturing a metal copper special-shaped part by photocuring, comprising:

[0009] S1. Preparation of photocurable slurry: A certain proportion of copper oxide precursor, photosensitive resin, photoinitiator and additives are fully mixed, and the mixture is ball-milled and vacuum-treated to obtain a photocurable slurry;

[0010] S2. Photocuring additive manufacturing: placing the photocuring slurry in a printer to perform additive manufacturing to obtain a copper oxide precursor blank;

[0011] S3. Heat treatment: degreasing, reducing and sintering the copper oxide precursor green body in sequence to obtain a dense metal copper special-shaped part.

[0012] Any of the possible implementations described above further provides an implementation, in which in step S1, the copper oxide precursor is nano-copper oxide or nano-cuprous oxide powder with a particle size of 50-200 nm.

[0013] Photosensitive resins are some unsaturated acrylic monomers containing carbon-carbon double bonds.

[0014] Initiators can activate these photosensitive resin molecules. When exposed to ultraviolet light of a specific wavelength, the carbon-carbon double bonds open and link with each other, linking the monomer molecules into long-chain molecules. This is a cross-linking reaction, and from a macroscopic perspective, the liquid resin turns into solid plastic.

[0015] There are two types of additives. One is surface modification, which adheres to the surface of the powder, allowing the powder to be evenly dispersed in the organic matter, reducing the viscosity of the system and facilitating printing. The other is light absorbing. Since ultraviolet light will be diffusely reflected when it is irradiated on the powder, the actual cured pattern will not match the designed model. The light absorber can absorb the scattered light to ensure printing accuracy.

[0016] According to any of the possible implementations described above, there is further provided an implementation, wherein in step S1, the volume percentage of the copper oxide precursor in the photocurable slurry is 40-50%;

[0017] The photosensitive resin includes one or more of acryloylmorpholine (ACMO), 1,6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), trimethylolpropane triacrylate (TPGDA), ethoxylated pentaerythritol tetraacrylate (PPTTA), polyurethane acrylate, epoxy acrylate, and polyester acrylate, and the volume ratio of the photosensitive resin in the photocurable slurry is 40%-50%;

[0018] The photoinitiator comprises one or more of 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester (TPO-L), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO), and 1-hydroxycyclohexylphenyl ketone (184), and the mass ratio of the photoinitiator to the photosensitive resin is 1%-5%.

[0019] Any possible implementation as described above further provides an implementation, in which in step S1, the adding includes one or more modifiers selected from the group consisting of silane coupling agent KH570, surface wetting agent BYK118, and oleic acid.

[0020] Any possible implementation as described above further provides an implementation, in which in step S1, the ball milling speed is 300-400 r / min, the ball milling time is 15-20 hours, and the vacuum degree is not greater than 0.1 MPa.

[0021] As for any possible implementation described above, a further implementation is provided, in which in step S2, the printer is a digital light processing (DLP) printer or a stereolithography (SLA) printer.

[0022] As for any possible implementation described above, an implementation is further provided, in which in step S3, the copper oxide precursor body is degreased at a certain temperature and in an inert atmosphere, and is reduced and sintered at a certain temperature and in a reducing atmosphere.

[0023] Any possible implementation as described above further provides an implementation, wherein the inert atmosphere for degreasing is argon or nitrogen, and the degreasing temperature range is 500-600°C; the reducing atmosphere is hydrogen, and the reducing temperature is 600-700°C; the sintering atmosphere is hydrogen, and the sintering temperature range is 850-950°C.

[0024] Any possible implementation as described above further provides an implementation, wherein the holding time for degreasing is not less than 1 hour, the holding time for reduction is not less than 1.5 hours, and the holding time for sintering is not less than 1.5 hours.

[0025] Any possible implementation described above further provides an implementation in which degreasing is divided into two stages:

[0026] On the other hand, the present invention also provides a special-shaped copper metal part, which is produced by the above method.

[0027] The beneficial effects of the present invention are:

[0028] 1. No need for high-energy laser beam to melt copper powder, metal copper components with uniform structure and excellent performance can be prepared.

[0029] 2. The equipment used is lower in cost than other additive manufacturing processes and has the ability to be mass-produced.

[0030] 3. Using oxide as a precursor reduces the density of pure copper powder by nearly 30% (the density of the resin is 1.1g / cm 3 The density of copper powder is about 8.96g / cm 3 , sedimentation is inevitable in the slurry. If copper oxide is used, the density is 6.31g / cm 3 , the density is reduced by 30%), and the prepared photosensitive slurry can remain stable for a long time without sedimentation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The figure shows a flow chart of a method for indirectly additively manufacturing a metal copper special-shaped part by photocuring according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following will describe in detail specific embodiments of the present invention with reference to the accompanying drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated, and they can be combined with each other to achieve better technical effects.

[0033] like Figure 1 As shown, a method for indirectly additively manufacturing a metal copper special-shaped part by photocuring in an embodiment of the present invention includes:

[0034] S1. Preparation of photocurable slurry: A certain proportion of copper oxide precursor, photosensitive resin, photoinitiator and additives are fully mixed, and the mixture is ball-milled and vacuum-treated to obtain a photocurable slurry;

[0035] S2. Photocuring additive manufacturing: placing the photocuring slurry in a printer to perform additive manufacturing to obtain a copper oxide precursor blank;

[0036] S3. Heat treatment: degreasing, reducing and sintering the copper oxide precursor green body in sequence to obtain a dense metal copper special-shaped part.

[0037] In a specific embodiment, in step S1, the copper oxide precursor is nano-copper oxide or nano-cuprous oxide powder with a particle size of 50-200 nm.

[0038] In a specific embodiment, in step S1, the volume percentage of the copper oxide precursor in the photocurable slurry is 40-50%;

[0039] The photosensitive resin includes one or more of acryloylmorpholine (ACMO), 1,6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), trimethylolpropane triacrylate (TPGDA), ethoxylated pentaerythritol tetraacrylate (PPTTA), polyurethane acrylate, epoxy acrylate, and polyester acrylate, and the volume ratio of the photosensitive resin in the photocurable slurry is 40%-50%;

[0040] The photoinitiator comprises one or more of 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester (TPO-L), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO), and 1-hydroxycyclohexylphenyl ketone (184), and the mass ratio of the photoinitiator to the photosensitive resin is 1%-5%.

[0041] In a specific embodiment, in step S1, the adding includes one or more modifiers such as silane coupling agent KH570, surface wetting agent BYK118, oleic acid, etc.

[0042] In a specific embodiment, in step S1, the ball milling speed is 300-400 r / min, the ball milling time is 15-20 hours, and the vacuum degree is 0.1 MPa.

[0043] In a specific embodiment, in step S2, the printer is a digital light processing (DLP) printer or a stereolithography (SLA) printer.

[0044] In a specific embodiment, in step S3, the copper oxide precursor body is degreased at a certain temperature in an inert atmosphere, and is reduced and sintered at a certain temperature in a reducing atmosphere.

[0045] In a specific embodiment, the inert atmosphere for degreasing is argon or nitrogen, and the degreasing temperature ranges from 500-600°C; the reducing atmosphere is hydrogen, and the reducing temperature ranges from 600-700°C; the sintering atmosphere is hydrogen, and the sintering temperature ranges from 850-950°C.

[0046] In a specific embodiment, the holding time for degreasing is not less than 1 hour, the holding time for reducing is not less than 1.5 hours, and the holding time for sintering is not less than 1.5 hours.

[0047] Example 1

[0048] A method for indirectly additively manufacturing a metal copper special-shaped part by photocuring, comprising:

[0049] S1. Weigh 50 parts by volume of copper oxide powder with a particle size of 100 nm, 15 parts by volume of HDDA, 15 parts by volume of PPTTA, and 20 parts by volume of polyurethane acrylate, uniformly mix, add 2% by volume of TPO photoinitiator based on the mass of the photosensitive resin, and 5% by volume of BYK118 modifier based on the mass of the powder; place the above mixture in a vacuum ball mill, evacuate the vacuum to 0.1 MPa, and ball mill at a speed of 350 r / min for 20 hours to obtain a copper oxide slurry;

[0050] S2, placing the copper oxide slurry in a DLP printer and printing to obtain a copper oxide precursor blank;

[0051] S3. In a tube furnace, heat to 600°C at a rate of 0.5°C / min and keep warm for 2 hours. Use argon atmosphere, heat to 600°C at a rate of 1°C / min and keep warm for 1 hour. Use air atmosphere, heat to 700°C at a rate of 10°C / min and keep warm for 2 hours. Use hydrogen atmosphere, heat to 950°C at a rate of 10°C / min and keep warm for 2 hours to obtain a three-dimensional special-shaped metallic copper component.

[0052] Example 2

[0053] A method for indirectly additively manufacturing a metal copper special-shaped part by photocuring, comprising:

[0054] S1. Weigh 60 parts by volume of copper oxide powder with a particle size of 100 nm, 20 parts by volume of HDDA, 10 parts by volume of TMPTA, and 10 parts by volume of polyurethane acrylate, uniformly mix, add 1% by volume of TPO photoinitiator based on the mass of the photosensitive resin, and 10% by volume of BYK118 modifier based on the mass of the powder; place the above mixture in a vacuum ball mill, evacuate the vacuum to 0.1 MPa, and ball mill at a speed of 400 r / min for 20 hours to obtain a copper oxide slurry;

[0055] S2, placing the copper oxide slurry in an SLA printer to print a copper oxide precursor green body;

[0056] S3. In a tube furnace, heat to 600°C at a rate of 0.3°C / min and keep warm for 2 hours. Use argon atmosphere, heat to 600°C at a rate of 0.8°C / min and keep warm for 1 hour. Use air atmosphere, heat to 700°C at a rate of 10°C / min and keep warm for 2 hours. Use hydrogen atmosphere, heat to 950°C at a rate of 10°C / min and keep warm for 2 hours to obtain a three-dimensional special-shaped metallic copper component.

[0057] Example 3

[0058] A method for indirectly additively manufacturing a metal copper special-shaped part by photocuring, comprising:

[0059] S1. Weigh 50 parts by volume of 200 nm cuprous oxide powder, 10 parts HDDA, 10 parts PPTTA, and 30 parts polyurethane acrylate and mix them evenly. Add 1% TPO photoinitiator by weight of the photosensitive resin and 10% BYK118 modifier by weight of the powder. Place the mixture in a vacuum mill, evacuate to a vacuum of 0.1 MPa, and mill at 350 rpm for 20 hours to obtain a copper oxide slurry.

[0060] S2, placing the copper oxide slurry in a DLP printer and printing to obtain a copper oxide precursor blank;

[0061] S3. In a tube furnace, heat to 600°C at a rate of 0.5°C / min and keep warm for 2 hours. Use argon atmosphere, heat to 600°C at a rate of 1°C / min and keep warm for 1 hour. Use air atmosphere, heat to 700°C at a rate of 10°C / min and keep warm for 2 hours. Use hydrogen atmosphere, heat to 950°C at a rate of 10°C / min and keep warm for 2 hours to obtain a three-dimensional special-shaped metallic copper component.

[0062] The innovative features of the present invention are as follows:

[0063] 1. Among existing metal printing technologies, selective laser melting offers the highest precision and quality. Its principle is to first lay a layer of powder, then scan it with a laser. However, this technology is not suitable for copper metal because copper has a very high reflectivity. When a high-energy laser beam is irradiated on copper powder, the vast majority of the laser light is reflected, preventing the copper powder from absorbing sufficient energy to melt. Furthermore, the reflected laser light can reflect off the lens, damaging the equipment. Therefore, there is no existing 3D printing technology for copper metal. This present invention represents a breakthrough in addressing this technical issue.

[0064] 2. The existing metal 3D printing technology requires each layer of powder to be spread before laser scanning, and the powder must have a certain fluidity. The fluidity of nanopowders is very poor and cannot be directly used in this technology. The powders used in the existing technology are all micron powders (nano powders cannot be used), and the metal parts prepared using micron powders have a large grain size of micron level. The present invention has made a breakthrough in this regard, using nano copper oxide powder in 3D printing. The metal grains of the copper special-shaped parts prepared by the process of the present invention are nano-scale, which is much smaller than the metal grain size prepared by traditional 3D printing technology. Therefore, the copper parts prepared in this application have better quality.

[0065] 3. The heat treatment process of the present invention is unique, dividing the heat treatment into three steps: debinding, reduction, and sintering. Conventional wisdom holds that, when reducing a solid part or blank using a reducing agent such as hydrogen (without damaging the part or blank), only the surface of the part or blank can be reduced, but the interior cannot be reduced, resulting in a pure metal part. Through extensive practice, the inventors have discovered that the heat treatment process of the present invention can fully address this technical problem, as explained below: Nanopowders are dispersed in a glue (i.e., a photosensitive resin). Upon exposure, the photosensitive resin transforms from a liquid to a solid, encapsulating the nanopowder and forming the blank. During the debinding process, the resin gradually decomposes and volatilizes. As the temperature rises, the resin is removed, leaving the powders loosely bonded together by friction, resulting in a very loose blank (containing voids). When the blank is heated in a hydrogen atmosphere, the hydrogen can fully penetrate the interior of the blank through the voids, causing a reduction reaction that reduces the copper oxide to pure copper. During sintering, as the temperature continues to rise, the contacting copper powders begin to transition from physical contact to chemical contact, forming a tight bond. At this point, the green body shrinks in size. Continued heat preservation allows the loose green body to sinter into a dense, pure copper bulk component. Experimental results demonstrate that the resulting parts are pure copper, free of unreduced copper oxide.

[0066] 4. In the embodiment of the present invention, the grain size of the copper after sintering can be controlled below 700 nm (the grain size of pure copper produced by the traditional powder metallurgy process is between a dozen microns and several tens of microns), which is much smaller than that of the traditional powder metallurgy process. The density reaches more than 90%, and there is no obvious texture, abnormal grain growth, second phase impurities and grain boundary liquid phase precipitates.

[0067] 5. Nano-oxide is used as a precursor, which will not decompose and release gas during the degreasing stage. Combined with the two-step degreasing method, the introduction of cracks and pores can be completely avoided.

[0068] 6. It can produce non-thin-wall parts and has the potential for industrial application.

[0069] Although several embodiments of the present invention have been described herein, those skilled in the art will appreciate that modifications may be made to the embodiments herein without departing from the spirit of the present invention. The above embodiments are merely exemplary and should not be used as limitations on the scope of the present invention.

Claims

1. A method for indirectly adding materials to produce special-shaped copper parts by photocuring, characterized in that: The method comprises: S1. Preparation of photocurable slurry: A certain proportion of copper oxide precursor, photosensitive resin, photoinitiator and additives are fully mixed, and after ball milling and vacuum treatment, a photocurable slurry is prepared; the copper oxide precursor is nano-copper oxide or nano-cuprous oxide powder with a particle size of 50-200 nm; the additives include one or more of silane coupling agent KH570, surface wetting agent BYK118, and oleic acid; the volume percentage of the copper oxide precursor in the photocurable slurry is 40-50%; the ball milling speed is 300-400 r / min, the ball milling time is 15-20 hours, and the vacuum degree is not greater than 0.1 MPa; S2. Photocuring additive manufacturing: placing the photocuring slurry in a printer to perform additive manufacturing to obtain a copper oxide precursor blank; S3. Heat treatment: The copper oxide precursor body is degreased, reduced and sintered in sequence to obtain a dense metal copper special-shaped part; the inert atmosphere for degreasing is argon or nitrogen, and the degreasing temperature range is 500-600°C; the reducing atmosphere is hydrogen, and the reducing temperature is 600-700°C; the sintering atmosphere is hydrogen, and the sintering temperature range is 850-950°C; the holding time for degreasing is not less than 1 hour, the holding time for reduction is not less than 1.5 hours, and the holding time for sintering is not less than 1.5 hours.

2. The method for indirectly additively manufacturing a metal copper special-shaped part by photocuring as claimed in claim 1, characterized in that: In step S1, the photosensitive resin includes one or more of acryloylmorpholine ACMO, 1,6-hexanediol diacrylate HDDA, tripropylene glycol diacrylate TPGDA, trimethylolpropane triacrylate TPGDA, ethoxylated pentaerythritol tetraacrylate PPTTA, polyurethane acrylate, epoxy acrylate, and polyester acrylate, and the volume ratio of the photosensitive resin in the photocurable slurry is 40%-50%; The photoinitiator includes one or more of 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester TPO-L, 2,4,6-trimethylbenzoyldiphenylphosphine oxide TPO, and 1-hydroxycyclohexylphenyl ketone, and the mass ratio of the photoinitiator to the photosensitive resin is 1%-5%.

3. The method for indirectly additively manufacturing a copper metal special-shaped part by photocuring as claimed in claim 1, characterized in that: In step S2, the printer is a digital light processing printer or a stereolithography printer.

4. A special-shaped copper part, characterized in that: The metal copper special-shaped part is produced by the method according to any one of claims 1 to 3.

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