Method for preparing copper alloy by metal powder injection molding and high-strength and high-conductivity copper alloy

Abstract

The present invention discloses a method for preparing copper alloy by metal powder injection molding and a high-strength and high-conductivity copper alloy, belonging to the technical field of powder metallurgy, including: mixing copper alloy and pure titanium powder to obtain mixed powder or pre-alloyed powder; mixing the mixed powder or pre-alloyed powder with a binder, and extruding after kneading to make granular feedstock; injecting the granular feedstock into a mold to form a green body; performing catalytic debinding on the green body; performing two-stage sintering on the green body after catalytic debinding to obtain a sintered part; and performing post-treatment on the sintered part to obtain the final alloy. This method can ensure that the finally sintered copper alloy has a high density and performance level.

Description

Technical Field

[0001] The present invention belongs to the technical field of powder metallurgy, and relates to a method for preparing copper alloy by metal powder injection molding and a high-strength and high-conductivity copper alloy. Background Art

[0002] A high-strength and high-conductivity copper alloy refers to a copper-based alloy that has high strength and high conductivity at the same time. As a type of high-performance copper alloy, high-strength and high-conductivity copper alloys are widely used in various key components for conducting electricity and heat. With the continuous development of miniaturization and complexity of components, manufacturing such components by machining is facing great difficulties and cost pressures, while using the near-net-shape forming technology of metal powder injection molding has significant advantages. However, when using water-atomized copper alloy powder or gas-atomized silicon-containing copper alloy powder, silicon dioxide is extremely likely to form on the powder surface during preparation and storage. These oxides coated on the powder surface seriously hinder the densification ability of the copper alloy during sintering in metal powder injection molding, resulting in low performance levels of sintered parts or even inability to sinter and form, greatly limiting the application of metal powder injection molding technology in precision components of high-performance copper alloys. Summary of the Invention

[0003] The purpose of the present invention is to solve the problem that silicon dioxide distributed on the surface of copper alloy powder hinders sintering densification, and provides a method for preparing copper alloy by metal powder injection molding and a high-strength and high-conductivity copper alloy. This method can greatly improve the density of sintered parts, thereby obtaining high-performance metal powder injection molding copper alloy materials.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] A method for preparing copper alloy by metal powder injection molding, comprising:

[0006] Mixing copper alloy and pure titanium powder to obtain mixed powder or pre-alloy powder;

[0007] Mixing the mixed powder or pre-alloy powder with a binder, and extruding after kneading to make granular feedstock;

[0008] Injecting the granular feedstock into a mold to form a green body;

[0009] Performing catalytic debinding on the green body;

[0010] Performing two-stage sintering on the catalytically debound green body to obtain a sintered part;

[0011] Performing post-treatment on the sintered part to obtain the final alloy.

[0012] As a further improvement of the present invention, the preparation of the mixed powder or pre-alloy powder by mixing copper alloy and pure titanium powder includes:

[0013] Using water atomized copper and copper alloy or gas atomized silicon-containing copper and copper alloy to prepare copper alloy pre-alloy powder with a particle size of 1-25 μm, adding pure titanium powder with a weight percentage of 0.05-0.2 wt% and a particle size of 10-25 μm to the copper alloy pre-alloy powder, and mixing and homogenizing to obtain the mixed powder;

[0014] Or,

[0015] Adding 0.05-0.2 wt% of pure titanium to the target copper alloy, and obtaining pre-alloy powder with a particle size of 1-25 μm after melting, water atomization or gas atomization.

[0016] As a further improvement of the present invention, the preparation of the granular feed by mixing the mixed powder with a binder, kneading and then extruding includes:

[0017] Mixing the mixed powder and the binder in a volume ratio of (1:1)-(3:1), heating and kneading to mix evenly, and then extruding, cutting and granulating to prepare the granular feed.

[0018] As a further improvement of the present invention, the injection of the granular feed into a mold to form a green body includes:

[0019] Using an injection molding machine to inject the granular feed into a mold to form a green body; the barrel temperature of the injection molding machine is 175-185 °C, the nozzle temperature is 190-200 °C, and the mold temperature is 90-120 °C.

[0020] As a further improvement of the present invention, the catalytic debinding of the green body includes:

[0021] Catalytically debinding the green body using an oxalic acid catalytic debinding furnace under a mixed gas of argon and hydrogen.

[0022] As a further improvement of the present invention, the process of catalytically debinding the green body is:

[0023] First preheating to a temperature of 95-120 °C for heat preservation; then using two-stage heating thermal debinding: heating from room temperature to 300 °C at a rate of 3-5 °C / min, holding for 30-90 min, and then continuing to heat to 600-700 °C at a rate of 2.5-3 °C / min, holding for 60-180 min.

[0024] As a further improvement of the present invention, the two-stage sintering of the catalytically debound green body to obtain a sintered part includes:

[0025] Under a mixed gas of argon and hydrogen, heating to 800 °C at a rate of 3-5 °C / min and holding for 20-30 min;

[0026] After converting to an argon atmosphere again, keep warm for another 20 - 60 min, then heat up to 900 °C at a rate of 3 - 5 °C / min, keep warm for 60 - 120 min, heat up to 1030 - 1060 °C at a rate of 3 - 5 °C / min, keep warm for 60 - 180 min, and cool down to 60 °C at a rate of 10 - 100 °C / min to obtain a sintered part.

[0027] As a further improvement of the present invention, the post - treatment of the sintered part to obtain the final alloy includes:

[0028] Heat the sintered part to 900 - 1050 °C, keep warm for 30 - 180 min, then water - quench; and keep warm at 400 - 600 °C for 60 - 360 min, and then water - quench or air - cool to obtain the final alloy.

[0029] A high - strength and high - conductivity copper alloy prepared by the method of preparing copper alloy by metal powder injection molding as described above.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention uses a method of preparing a high - density and high - performance copper alloy by metal powder injection molding. By introducing coarse titanium powder with good solid solubility for oxygen and capable of effectively reducing silicon oxide, the isolation between the oxide coatings on the copper matrix is removed, and a copper powder - titanium powder - copper auxiliary powder channel beneficial to sintering densification can be promoted. Further, the lower melting temperature of the intermetallic compound formed after the copper - titanium reaction is used to form a liquid phase to promote sintering. And in the sintering process, multi - level treatment is carried out on the discharge of water vapor generated during the reduction of oxidized copper powder, minimizing its harm to density and performance. Moreover, a two - stage sintering process is set to achieve multi - level and orderly densification of the sintered part, so as to ensure that the finally sintered copper alloy has a high density and performance level. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 It is a flow chart of the method for preparing copper alloy by metal powder injection molding provided by the present invention;

[0034] Figure 2Schematic diagram of the transformation and interface state after the contact between the titanium powder in the silicon bath and the surface of the copper alloy under high temperature in the present invention: (a) adding elemental pure titanium powder to the alloy powder; (b) mixing an appropriate amount of titanium with the target copper alloy and melting to prepare a pre-alloy powder.

[0035] Figure 3 Microstructure (a) of the material obtained by sintering and processing the water-atomized CuNiSiCr alloy powder without adding Ti powder under the above process and its elemental distribution maps (b: oxygen element distribution, c: Si element distribution). Detailed implementation manners

[0036] In order to make the technical problems to be solved, technical solutions and beneficial effects of the present application clearer and more understandable, the following further details the present application in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0037] In the present application, the term "and / or" describes the association relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Wherein A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0038] In the present application, "at least one" means one or more, and "a plurality" means two or more. "At least one (item)" or its similar expression below refers to any combination of these items, including any combination of single item (item) or plural items (items). For example, "at least one (item) of a, b, or c", or, "at least one (item) of a, b, and c" can both represent: a, b, c, a~b (that is, a and b), a~c, b~c, or a~b~c, where a, b, and c can be single or multiple respectively.

[0039] It should be understood that in various embodiments of the present application, the magnitudes of the serial numbers of the above processes do not mean the order of execution. Some or all steps can be executed in parallel or successively. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0040] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms of "a", "the", and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0041] In the description of the embodiments of the present application, the weight of the relevant components mentioned not only can refer to the specific content of each component, but also can represent the proportional relationship of the weights between the components. Therefore, as long as the content of the relevant components in the description of the embodiments of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the description of the embodiments of the present application. Specifically, the mass described in the description of the embodiments of the present application can be mass units well-known in the chemical industry such as µg, mg, g, kg, etc.

[0042] Regarding the problem that the silicon dioxide distributed on the surface of the copper alloy powder hinders sintering densification, in the existing water atomized powder preparation method or in the preparation and storage process of the silicon-containing copper alloy powder, silicon dioxide distributed diffusely is extremely easy to generate on the powder surface. These oxides are difficult to be reduced during the sintering process and block the contact of the fresh copper matrix in the adjacent powders, greatly retarding the densification speed and degree of the alloy, and there are serious problems such as low performance level of the sintered parts or even inability to sinter and form. Therefore, it is urgent to develop a method to relieve the restriction of stable silicon dioxide on the copper alloy sintering densification process.

[0043] As Figure 1 shown, the present invention provides a method for preparing copper alloy by metal powder injection molding. This method eliminates the adverse effects of silicon dioxide by introducing alloying elements and optimizing with the sintering process. The means include:

[0044] S1, mixing copper alloy and pure titanium powder to obtain a mixed powder or a pre-alloy powder;

[0045] S2, mixing the mixed powder or the pre-alloy powder with a binder, and extruding after kneading to make a granular feedstock;

[0046] S3, injecting the granular feedstock into a mold to form a green body;

[0047] S4, performing catalytic debinding on the green body;

[0048] S5, performing two-stage sintering on the green body after catalytic debinding to obtain a sintered part;

[0049] S6, performing post-treatment on the sintered part to obtain the final alloy.

[0050] The following is a further detailed description of the present invention:

[0051] A method for preparing copper alloy by metal powder injection molding includes the following steps:

[0052] Step 1: Select pre-alloyed copper alloy powder with a particle size of 1 - 25 μm (mainly water-atomized copper and copper alloy or gas-atomized silicon-containing copper and copper alloy) as the raw material. Add pure titanium powder with a particle size of 10 - 25 μm and a weight percentage of 0.05 - 0.2 wt% to the above raw material, and mix evenly in a mixer, or prepare the target copper alloy and add 0.05 - 0.2 wt% of pure titanium. After melting, water atomization or gas atomization to make powder, pre-alloyed powder with a particle size of 1 - 25 μm is obtained;

[0053] Step 2: Mix the mixed powder and the binder in a volume ratio of 1:1 - 3:1, heat to 180 °C in a granulator, knead for 300 min, then extrude and cut into pellets to make a particle feed of Φ2.5 mm × 3.2 mm;

[0054] Step 3: Use an injection machine to inject the particle feed into a mold to form a green body, where the barrel temperature is 175 - 185 °C, the nozzle temperature is 190 - 200 °C, and the mold temperature is 90 - 120 °C;

[0055] Step 4: Use an oxalic acid catalytic debinding furnace to conduct catalytic debinding on the green body under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 8:2 - 9:1), at a temperature of 95 - 120 °C for 300 min. Then, perform two-stage heating thermal debinding: heat from room temperature to 300 °C at a rate of 3 - 5 °C / min, hold for 30 - 90 min, and then continue to heat to 600 - 700 °C at a rate of 2.5 - 3 °C / min, hold for 60 - 180 min;

[0056] Step 5: Heat to 800 °C at a rate of 3 - 5 °C / min under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 8:2 - 9:1), hold for 20 - 30 min, switch to an argon atmosphere with a purity of 99.999% and hold for another 20 - 60 min. Then, heat to 900 °C at a rate of 3 - 5 °C / min, hold for 60 - 120 min, heat to 1030 - 1060 °C at a rate of 3 - 5 °C / min, hold for 60 - 180 min, and cool to 60 °C at a rate of 10 - 100 °C / min and then take out;

[0057] Step 6: Put the sintered part into a high-temperature furnace at a temperature of 900 - 1050 °C, hold for 30 - 180 min, then water quench, and then put it into a high-temperature furnace at 400 - 600 °C, hold for 60 - 360 min, and then water quench or air cool to obtain the final alloy.

[0058] Combined Figure 2 The functions and principles of each step are analyzed as follows:

[0059] First, select coarse titanium powder with a smaller specific surface area as the raw material, so that the proportion of the oxidized part on the surface layer of the titanium powder in the whole powder is extremely small. Then, utilize the good solid solution ability of titanium powder for oxygen in the temperature range of 600-700 °C, so that it can expose the fresh matrix in this temperature range, and use a reducing atmosphere to reduce the oxidized copper powder in this temperature range to prevent cracks from being generated inside the powder due to the high pressure formed by the water vapor generated during high-temperature reduction. Secondly, rely on the good reduction ability of fresh titanium for silicon oxide to solve the sintering difficulty caused by the isolation of the oxide from the copper matrix, and further utilize the high reaction activity between copper and titanium to form a diffusion channel between copper powder - titanium powder - copper powder. Moreover, the intermetallic compound formed by the reaction of copper and titanium can form a low-melting-point liquid phase between 800-900 °C, which can further accelerate the element diffusion rate and promote sintering. Finally, after fully reducing the oxidized copper powder at a high temperature of about 800 °C and converting the atmosphere into an inert atmosphere, a constant-temperature blowing process is specifically set before large-scale sintering to ensure that the water vapor generated by reduction completely escapes to reduce the number of defects in the sintered parts. Then, two-stage sintering processes above 1000 °C and above 900 °C are set to achieve multi-stage densification of the sintered parts.

[0060] Through the above process, the problem of difficult sintering densification caused by oxide-coated copper alloy powder can be effectively solved, and the density of the sintered parts can be greatly improved, so as to obtain a high-performance metal powder injection molding copper alloy material.

[0061] In the embodiment, in step 1 of the embodiment of the present application, the copper alloy has a particle size of 1-25 μm, and can also be 10-20 μm, specifically typical but non-limiting particle sizes such as 1 μm, 2 μm, 3 μm, 5 μm, 7 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, etc.

[0062] In a further embodiment, the weight percentage of pure titanium powder is 0.05-0.2 wt%, and can also be 0.1-0.2 wt%, specifically typical but non-limiting weight percentages such as 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.1 wt%, 0.12 wt%, 0.14 wt%, 0.15 wt%, 0.18 wt%, 0.2 wt%, etc.

[0063] In a further embodiment, the particle size of pure titanium powder is 10-25 μm, and can also be 10-20 μm, specifically typical but non-limiting particle sizes such as 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, etc.

[0064] In a further embodiment, the particle size of the pre-alloyed powder is 1 to 25 μm; it can also be 10 to 20 μm, specifically 1 μm, 2 μm, 3 μm, 5 μm, 7 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, etc., which are typical but non-limiting particle sizes.

[0065] In the embodiment, in step 2 of the embodiment of the present application, the volume ratio of the mixed powder to the binder is 1:1 to 3:1, specifically it can be 1:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 3:1, etc., which are typical but non-limiting ratios.

[0066] In the embodiment, in step 3 of the embodiment of the present application, the temperature of the barrel is 175 to 185 °C, specifically it can be 175 °C, 178 °C, 179 °C, 180 °C, 181 °C, 182 °C, 183 °C, 185 °C, etc., which are typical but non-limiting temperatures. The temperature of the nozzle is 190 to 200 °C, specifically it can be 190 °C, 192 °C, 195 °C, 196 °C, 198 °C, 200 °C, etc., which are typical but non-limiting temperatures. The temperature of the mold is 90 to 120 °C; specifically it can be 90 °C, 95 °C, 98 °C, 100 °C, 105 °C, 106 °C, 109 °C, 110 °C, 115 °C, 117 °C, 119 °C, 120 °C, etc., which are typical but non-limiting temperatures.

[0067] In the embodiment, in step 4 of the embodiment of the present application, the initial temperature of catalytic debinding is 95 to 120 °C, specifically it can be 95 °C, 98 °C, 100 °C, 105 °C, 106 °C, 109 °C, 110 °C, 115 °C, 117 °C, 119 °C, 120 °C, etc., which are typical but non-limiting temperatures.

[0068] In a further embodiment, it is heated to 600 to 700 °C, specifically it can be 600 °C, 610 °C, 620 °C, 630 °C, 640 °C, 650 °C, 655 °C, 660 °C, 670 °C, 680 °C, 690 °C, 700 °C, etc., which are typical but non-limiting temperatures.

[0069] In the embodiment, in step 5 of the embodiment of the present application, it is heated to 1030 to 1060 °C, specifically it can be 1030 °C, 1035 °C, 1038 °C, 1040 °C, 1043 °C, 1045 °C, 1048 °C, 1050 °C, 1053 °C, 1057 °C, 1058 °C, 1060 °C, etc., which are typical but non-limiting temperatures.

[0070] In the embodiment, in step 6 of the embodiment of the present application, the temperature is 900 - 1050°C, specifically, typical but non-limiting temperatures such as 900°C, 905°C, 908°C, 1000°C, 1005°C, 1010°C, 1015°C, 1020°C, 1030°C, 1035°C, 1040°C, 1046°C, 1050°C, etc.

[0071] In a further embodiment, the temperature is 400 - 600°C, specifically, typical but non-limiting temperatures such as 400°C, 405°C, 410°C, 420°C, 450°C, 480°C, 500°C, 510°C, 520°C, 550°C, 560°C, 580°C, 590°C, 600°C, etc.

[0072] In a second aspect, the present application provides a high-strength and high-conductivity copper alloy prepared by the method for preparing a copper alloy by metal powder injection molding as described above. Based on the components contained in the composite photothermal material and the structure formed by each component in the embodiment of the present application, and giving the same concept as the method for preparing a copper alloy by metal powder injection molding as described above, the high-strength and high-conductivity copper alloy prepared by this method has a relatively high density and performance level. This metal powder injection molding process can be better applied in high-performance copper alloy precision parts, especially as an application of a high-strength and high-conductivity copper alloy.

[0073] The following uses multiple specific examples to illustrate the copper alloy and its preparation method and the like in the embodiment of the present application.

[0074] Example 1

[0075] (1) Select water atomized CuNi pre-alloy powder with a particle size of 1 μm as the raw material, add 0.05 wt% of pure titanium powder with a particle size of 10 μm to the above raw material, and mix well in a mixer;

[0076] (2) Mix the mixed powder and the binder in a volume ratio of 1:1, heat to 180°C in a granulator, knead for 300 min, then extrude and cut into particles to make particle feed with a size of Φ2.5 mm × 3.2 mm;

[0077] (3) Use an injection machine to inject the particle feed into a mold to form a green body, where the barrel temperature is 175°C, the nozzle temperature is 190°C, and the mold temperature is 90°C;

[0078] (4) Use an oxalic acid catalytic debinding furnace to perform catalytic debinding on the green body under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 8:2), the temperature is 95°C, the time is 300 min, and then use two-stage heating thermal debinding: heat from room temperature to 300°C at a rate of 3°C / min, hold for 30 min, and then continue to heat to 600°C at a rate of 2.5°C / min and hold for 60 min;

[0079] (5)Under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 8:2), heat it at 3 °C / min to 800 °C, hold for 20 min, switch to an argon atmosphere with a purity of 99.999% and hold for another 20 min, then heat it at 3 °C / min to 900 °C, hold for 60 min, heat it at 3 °C / min to 1030 - 1060 °C, hold for 60 min, and cool it to 60 °C at 10 °C / min and then take it out;

[0080] (6)Put the sintered part into a high-temperature furnace at 900 °C, hold for 30 min and then water quench, and then put it into a high-temperature furnace at 400 °C, hold for 360 min and then water quench and cool to obtain the final alloy.

[0081] Example 2

[0082] (1)Select gas-atomized CuNiSi pre-alloy powder with a particle size of 25 μm as the raw material, add 0.2 wt% of pure titanium powder with a particle size of 25 μm to the above raw material, and mix evenly in a mixer;

[0083] (2)Mix the mixed powder and the binder in a volume ratio of 3:1, heat it to 180 °C in a granulator, knead for 300 min, then extrude and cut into pellets to make particle feed of Φ2.5 mm × 3.2 mm;

[0084] (3)Use an injection machine to inject the particle feed into a mold to form a green body, where the barrel temperature is 185 °C, the nozzle temperature is 200 °C, and the mold temperature is 120 °C;

[0085] (4)Under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 9:1), use an oxalic acid catalytic debinding furnace to catalytically debind the green body at a temperature of 120 °C for 300 min, and then use two-stage heating thermal debinding: heat from room temperature to 300 °C at 5 °C / min, hold for 90 min, and then continue to heat to 700 °C at 3 °C / min and hold for 180 min;

[0086] (5)Under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 9:1), heat it at 5 °C / min to 800 °C, hold for 30 min, switch to an argon atmosphere with a purity of 99.999% and hold for another 60 min, then heat it at 5 °C / min to 900 °C, hold for 120 min, heat it at 5 °C / min to 1060 °C, hold for 180 min, and cool it to 60 °C at 100 °C / min and then take it out;

[0087] (6)Put the sintered part into a high-temperature furnace at 1050 °C, hold for 180 min and then water quench, and then put it into a high-temperature furnace at 600 °C, hold for 60 min and then air cool to obtain the final alloy.

[0088] Example 3

[0089] (1) Select water atomized CuNiSiCr pre-alloyed powder with a particle size of 10 μm as the raw material. After adding 0.1 wt% of pure titanium powder with a particle size of 15 μm to the above raw material, mix them evenly in a mixer;

[0090] (2) Mix the mixed powder and the binder in a volume ratio of 2:1, heat it to 180 °C in a granulator, knead it for 300 min, then extrude and cut it into particles to make a particle feed of Φ2.5 mm × 3.2 mm;

[0091] (3) Use an injection machine to inject the particle feed into a mold to form a green body, where the barrel temperature is 180 °C, the nozzle temperature is 195 °C, and the mold temperature is 100 °C;

[0092] (4) Catalytic debinding of the green body is carried out in an oxalic acid catalytic debinding furnace under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 5:1), at a temperature of 100 °C for 300 min, and then two-stage heating thermal debinding is carried out: heat from room temperature to 300 °C at a rate of 4 °C / min, hold for 60 min, and then continue to heat to 650 °C at a rate of 2.7 °C / min and hold for 80 min;

[0093] (5) Heat to 800 °C at a rate of 4 °C / min under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 6:1), hold for 25 min, switch to an argon atmosphere with a purity of 99.999% and hold for another 40 min, then heat to 900 °C at a rate of 4 °C / min and hold for 80 min, heat to 1050 °C at a rate of 4 °C / min and hold for 120 min, and cool to 60 °C at a rate of 80 °C / min and then take it out;

[0094] (6) Put the sintered part into a high-temperature furnace at 1000 °C, hold for 120 min and then water quench, and then put it into a high-temperature furnace at 500 °C, hold for 180 min and then water quench and cool to obtain the final alloy.

[0095] Example 4

[0096] (1) Prepare a CuNiSi target alloy and add 0.05 wt% of pure titanium, and prepare a pre-alloyed powder with a particle size of 1 μm by water atomization;

[0097] (2) Mix the mixed powder and the binder in a volume ratio of 1:1, heat it to 180 °C in a granulator, knead it for 300 min, then extrude and cut it into particles to make a particle feed of Φ2.5 mm × 3.2 mm;

[0098] (3) Use an injection machine to inject the particle feed into a mold to form a green body, where the barrel temperature is 175 °C, the nozzle temperature is 190 °C, and the mold temperature is 90 °C;

[0099] (4) The green compact was catalytically debound using an oxalic acid catalytic debinding furnace under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 8:2) at a temperature of 95 °C for 300 min, and then two-stage heating thermal debinding was carried out: heating from room temperature to 300 °C at a rate of 3 °C / min, holding for 30 min, and then continuing to heat to 600 °C at a rate of 2.5 °C / min and holding for 60 min;

[0100] (5) Heating to 800 °C at a rate of 3 °C / min under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 8:2), holding for 20 min, switching to an argon atmosphere with a purity of 99.999% and holding for another 20 min, then heating to 900 °C at a rate of 3 °C / min, holding for 60 min, heating to 1030 - 1060 °C at a rate of 3 °C / min, holding for 60 min, and cooling to 60 °C at a rate of 10 °C / min and then taking out;

[0101] (6) The sintered part was placed in a high-temperature furnace at 900 °C and held for 30 min, then water quenched, and then placed in a high-temperature furnace at 400 °C and held for 360 min and then water quenched and cooled to obtain the final alloy.

[0102] Example 5

[0103] (1) Prepare a CuNiSiCr target alloy and add 0.2 wt% of pure titanium, and obtain a pre-alloy powder with a particle size of 25 μm by gas atomization;

[0104] (2) Mix the mixed powder and the binder in a volume ratio of 3:1, heat to 180 °C in a granulator, knead for 300 min, then extrude and pelletize to make a particle feed of Φ2.5 mm × 3.2 mm;

[0105] (3) Use an injection molding machine to inject the particle feed into a mold to form a green body, where the barrel temperature is 185 °C, the nozzle temperature is 200 °C, and the mold temperature is 120 °C;

[0106] (4) The green compact was catalytically debound using an oxalic acid catalytic debinding furnace under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 9:1) at a temperature of 120 °C for 300 min, and then two-stage heating thermal debinding was carried out: heating from room temperature to 300 °C at a rate of 5 °C / min, holding for 90 min, and then continuing to heat to 700 °C at a rate of 3 °C / min and holding for 180 min;

[0107] (5)Under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 9:1), heat it up to 800 °C at a rate of 5 °C / min, hold for 30 min, then switch to an argon atmosphere with a purity of 99.999% and hold for another 60 min. Then heat it up to 900 °C at a rate of 5 °C / min, hold for 120 min, heat it up to 1060 °C at a rate of 5 °C / min, hold for 180 min, and cool it down to 60 °C at a rate of 100 °C / min and then take it out;

[0108] (6)Put the sintered part into a high-temperature furnace at 1050 °C, hold for 180 min, then quench it in water, and then put it into a high-temperature furnace at 600 °C, hold for 60 min, and then air-cool to obtain the final alloy.

[0109] Example 6

[0110] (1)Prepare a CuNiSiCr target alloy and add 0.1 wt% of pure titanium, and prepare pre-alloyed powder with a particle size of 10 μm by water atomization;

[0111] (2)Mix the mixed powder and the binder in a volume ratio of 2:1, heat it to 180 °C in a granulator, knead for 300 min, then extrude and pelletize to make a particle feed of Φ2.5 mm × 3.2 mm;

[0112] (3)Use an injection machine to inject the particle feed into a mold to form a green body, where the barrel temperature is 180 °C, the nozzle temperature is 195 °C, and the mold temperature is 100 °C;

[0113] (4)Under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 5:1), use an oxalic acid catalytic debinding furnace to catalytically debind the green body at a temperature of 100 °C for 300 min, and then use two-stage heating thermal debinding: heat from room temperature to 300 °C at a rate of 4 °C / min, hold for 60 min, and then continue to heat to 650 °C at a rate of 2.7 °C / min, hold for 100 min;

[0114] (5)Under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 6:1), heat it up to 800 °C at a rate of 4 °C / min, hold for 25 min, switch to an argon atmosphere with a purity of 99.999% and hold for another 40 min, then heat it up to 900 °C at a rate of 4 °C / min, hold for 80 min, heat it up to 1050 °C at a rate of 4 °C / min, hold for 120 min, and cool it down to 60 °C at a rate of 80 °C / min and then take it out;

[0115] (6)Put the sintered part into a high-temperature furnace at 1000 °C, hold for 120 min, then quench it in water, and then put it into a high-temperature furnace at 500 °C, hold for 180 min, and then quench it to obtain the final alloy.

[0116] Example 7

[0117] (1) Configure the CuNiSiCr target alloy, add 0.1 wt% of pure titanium, and prepare pre-alloyed powder with a particle size of 10 μm by water atomization;

[0118] (2) Mix the mixed powder and the binder in a volume ratio of 2:1, heat it to 180 °C in a granulator, knead it for 300 min, then extrude and pelletize to make a granular feed of Φ2.5 mm × 3.2 mm;

[0119] (3) Use an injection machine to inject the granular feed into a mold to form a green body, where the barrel temperature is 180 °C, the nozzle temperature is 195 °C, and the mold temperature is 100 °C;

[0120] (4) Catalytically debind the green body in an oxalic acid catalytic debinding furnace under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 5:1) at a temperature of 100 °C for 300 min, and then perform two-stage heating thermal debinding: heat from room temperature to 300 °C at a rate of 4 °C / min, hold for 60 min, and then continue to heat to 600 °C at a rate of 3 °C / min and hold for 60 min;

[0121] (5) Heat to 800 °C at a rate of 4 °C / min under a mixed gas of argon and hydrogen with a purity of 99.999% (volume ratio 6:1), hold for 30 min, switch to an argon atmosphere with a purity of 99.999% and hold for another 40 min, then heat to 900 °C at a rate of 4 °C / min, hold for 80 min, heat to 1050 °C at a rate of 3 °C / min, hold for 100 min, and cool to 60 °C at a rate of 80 °C / min and then take out;

[0122] (6) Put the sintered part into a high-temperature furnace at 900 °C, hold for 60 min, then water quench, and then put it into a high-temperature furnace at 510 °C, hold for 180 min, and then water quench and cool to obtain the final alloy.

[0123] Performance Test

[0124] Figure 3 Shown are the microstructures ( Figure 3 in a) and the element distribution maps ( Figure 3 in b: oxygen element distribution, Figure 3 in c: Si element distribution) of the materials obtained by sintering and processing the water-atomized CuNiSiCr alloy powder without adding Ti powder under the above process. It can be seen that the powder particles are completely wrapped by SiO 2 particles. During sintering, the copper matrices cannot contact each other, resulting in a very low density of the final material, close to that of loose powder. By using Ti powder at high temperature to react with SiO 2Its high reactivity can effectively break the oxide layer covering the surface of the powder particles, thereby promoting the connection and densification of the fresh copper alloy matrix, greatly improving the densification of the final sintered part and the performance of the final material.

[0125] All articles and references disclosed above, including patent applications and publications, are incorporated herein by reference for various purposes. The term "consisting essentially of" describing a combination shall include the identified elements, components, parts or steps, and other elements, components, parts or steps that do not substantially affect the basic novel features of the combination. The use of the terms "comprising" or "including" to describe the combinations of elements, components, parts or steps herein also contemplates embodiments consisting essentially of these elements, components, parts or steps. By using the term "may" herein, it is intended to indicate that any attribute described as "may" included is optional.

[0126] A plurality of elements, components, parts or steps can be provided by a single integrated element, component, part or step. Alternatively, a single integrated element, component, part or step can be divided into separate multiple elements, components, parts or steps. The disclosure of "a" or "an" used to describe an element, component, part or step does not preclude other elements, components, parts or steps.

[0127] It should be understood that the above description is for illustration purposes and not for limitation. By reading the above description, many embodiments and many applications other than the provided examples will be obvious to those skilled in the art. Therefore, the scope of the present teachings should not be determined with reference to the above description, but should be determined with reference to the full scope of the foregoing claims and the equivalents of these claims. For completeness purposes, all articles and references including patent applications and published disclosures are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended to abandon such subject matter, nor should it be considered that the applicant has not considered such subject matter as part of the disclosed inventive subject matter.

Claims

1. A method for preparing copper alloy by metal powder injection molding, characterized in that, it includes: Mixing copper alloy and pure titanium powder to obtain mixed powder or pre-alloy powder; Mixing the mixed powder or pre-alloy powder with a binder, and extruding after kneading to make granular feedstock; Injecting the granular feedstock into a mold to form a green compact; Performing catalytic debinding on the green compact; the process of performing catalytic debinding on the green compact is: First preheating to a temperature of 95 - 120 °C for heat preservation; then adopting two-stage heating thermal debinding: heating from room temperature to 300 °C at a rate of 3 - 5 °C / min, holding for 30 - 90 min, and then continuing to heat to 600 - 700 °C at a rate of 2.5 - 3 °C / min, holding for 60 - 180 min; Performing two-stage sintering on the catalytically debound green compact to obtain a sintered part; The process of performing two-stage sintering on the catalytically debound green compact to obtain a sintered part includes: Under a mixed gas of argon and hydrogen, heating to 800 °C at a rate of 3 - 5 °C / min, and holding for 20 - 30 min; Then switching to an argon atmosphere and holding for another 20 - 60 min, then heating to 900 °C at a rate of 3 - 5 °C / min, holding for 60 - 120 min, heating to 1030 - 1060 °C at a rate of 3 - 5 °C / min, holding for 60 - 180 min, and cooling to 60 °C at a rate of 10 - 100 °C / min to obtain a sintered part; Performing post-treatment on the sintered part to obtain the final alloy; Among them, the process of mixing copper alloy and pure titanium powder to obtain mixed powder or pre-alloy powder includes: Using water atomized copper and copper alloy or gas atomized silicon-containing copper and copper alloy to obtain copper alloy pre-alloy powder with a particle size of 1 - 25 μm, adding pure titanium powder with a weight percentage of 0.05 - 0.2 wt% and a particle size of 10 - 25 μm to the copper alloy pre-alloy powder, and mixing evenly to obtain mixed powder.

2. The method for preparing copper alloy by metal powder injection molding according to claim 1, characterized in that, the process of mixing the mixed powder with a binder, and extruding after kneading to make granular feedstock includes: Mixing the mixed powder and the binder in a volume ratio of (1:1) - (3:1), heating and kneading to mix evenly, and then extruding, cutting and granulating to make granular feedstock.

3. The method for preparing copper alloy by metal powder injection molding according to claim 1, characterized in that, the process of injecting the granular feedstock into a mold to form a green compact includes: Using an injection machine to inject the granular feedstock into a mold to form a green compact; the barrel temperature of the injection machine is 175 - 185 °C, the nozzle temperature is 190 - 200 °C, and the mold temperature is 90 - 120 °C.

4. The method for preparing copper alloy by metal powder injection molding according to claim 1, characterized in that, the process of performing catalytic debinding on the green compact includes: Under a mixed gas of argon and hydrogen, using an oxalic acid catalytic debinding furnace to perform catalytic debinding on the green compact.

5. The method for preparing copper alloy by metal powder injection molding according to claim 1, characterized in that, the process of performing post-treatment on the sintered part to obtain the final alloy includes: Heat the sintered part to 900 - 1050 °C and hold for 30 - 180 min, then perform water quenching; and hold at 400 - 600 °C for 60 - 360 min and then perform water quenching or air cooling to obtain the final alloy.

6. A high-strength and high-conductivity copper alloy prepared by the method for preparing a copper alloy by metal powder injection molding according to any one of claims 1 to 5.

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