High copper content feedstock for powder injection molding and method of making, using same

Abstract

The application discloses a high-copper-content feed for powder injection molding and a preparation method and application thereof, and relates to the technical field of powder injection molding materials. The high-copper-content feed is prepared by mixing metal powder and catalytic debinding binder in a mass ratio of 120-130:5-15 and then performing dense mixing. The metal powder comprises copper-containing powder, and the mass fraction of copper powder in the copper-containing powder is 95-100%. The copper powder comprises three kinds of powders with different particle sizes. By controlling the selection of raw materials of the copper powder, a combination of copper powder raw materials with multiple particle sizes and multiple shapes is screened out, and then the high-copper-content feed is prepared by mixing the copper powder with the catalytic debinding binder and performing dense mixing. The high-copper-content feed has the advantages of strong flowability and good shape maintaining capability, and the structure of a part product obtained by powder injection molding is compact, and the molding rate is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of powder injection molding materials, in particular to a high-copper-content feedstock for powder injection molding and a preparation method and application thereof. BACKGROUND

[0002] Powder injection molding is a manufacturing process that mixes metal or ceramic powder with a binder and then injection molds, which combines traditional injection molding and powder metallurgy technology to produce complex-shaped and high-precision parts.

[0003] Copper has the characteristics of high strength, high thermal conductivity and high ductility, and its density is 8.90 g / cm 3 , which is widely used in electrical, electronic, construction, light industry and national defense fields, and is second only to aluminum in China's non-ferrous metal material consumption. However, copper is an active metal that is easily oxidized and contaminated at high temperatures, which seriously affects its machining performance and material properties. When using traditional processing methods such as casting, die casting, hot and cold processing, and machining to prepare copper parts, the material utilization rate is low, and the cost is high.

[0004] Therefore, using copper as a feedstock for powder injection molding process not only can take advantage of the high strength, high thermal conductivity and high ductility of copper, but also can improve the utilization rate of copper compared to traditional processing methods, which has excellent application value.

[0005] The powder injection molding process includes four stages: mixing, forming, debinding and sintering. Among them, debinding is one of the most complex and important links in the powder injection molding process. The existing copper-containing feedstock in the powder injection molding process is prone to deformation due to the influence of gravity when debinding when the copper content in the feedstock is high, which affects the shape of the final produced parts, resulting in low yield and resource waste. Moreover, the higher the copper content, the more obvious this phenomenon is, and currently there are many parts products that need to be prepared using pure copper feedstock, further aggravating this phenomenon. In addition, the existing copper feedstock for powder injection molding has poor rheological properties, low sintering density, low thermal conductivity and elongation, and the process repeatability is difficult, which seriously restricts the application and development of copper powder injection molding.

[0006] Therefore, the present application is proposed. SUMMARY

[0007] The present application relates to the technical field of powder injection molding materials, in particular to a high-copper-content feedstock for powder injection molding and a preparation method and application thereof.

[0008] The present application is implemented as follows:

[0009] In a first aspect, the present application provides a method for preparing a high-copper-content feedstock for powder injection molding, comprising mixing metal powder and catalytic debinding binder in a mass ratio of 120-130:5-15 and then densifying.

[0010] The metal powder comprises copper-containing powder, and the mass fraction of copper powder in the copper-containing powder is 95-100%.

[0011] The copper powder comprises first particle size powder, second particle size powder and third particle size powder, and the particle size relationship is: first particle size powder > second particle size powder > third particle size powder, the third particle size powder is near-spherical nano powder, the first particle size powder and the second particle size powder are both spherical micron powder, and the particle size of the first particle size powder satisfies D 50 = 5.5-6.5 μm.

[0012] In a second aspect, the present application provides a high-copper-content feedstock for powder injection molding, which is prepared by the method of any one of the preceding embodiments.

[0013] In a third aspect, the present application provides an application of the method of any one of the preceding embodiments to preventing deformation of the feedstock during powder injection molding.

[0014] The present application has the following beneficial effects:

[0015] The present application provides a high-copper-content feedstock for powder injection molding, a method for preparing the same and an application thereof, by controlling the selection of copper powder raw materials, screening a combination of copper powder raw materials with multiple particle sizes and multiple shapes, and then mixing with catalytic debinding binder and densifying, the prepared high-copper-content feedstock has the advantages of strong flowability and good shape retention capability, and the obtained part product has a compact structure and a high molding rate. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and other related drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0017] Figure 1 EBSD microstructure morphology diagram of a copper part after sintering of the pure copper feedstock provided in embodiment 1 of the present application by powder injection molding;

[0018] Figure 2 Tensile property diagram of a copper part after sintering of the pure copper feedstock provided in embodiment 1 and embodiment 2 of the present application by powder injection molding. DETAILED DESCRIPTION

[0019] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. If specific conditions are not indicated in the embodiments, the conventional conditions or the conditions suggested by the manufacturers are adopted. If the manufacturers of the reagents or instruments are not indicated, the conventional products that can be purchased in the market are adopted.

[0020] The features and performances of the present application will be further described in detail below in combination with the embodiments.

[0021] Since the specific gravity of copper is large, the deformation is easily caused by the self-weight during the degreasing, thereby affecting the shape of the final produced part, resulting in low yield and resource waste, and the higher the copper content, the more obvious the case. In order to solve this technical problem, the inventors propose the following technical solutions.

[0022] In a first aspect, the present application provides a preparation method of high-copper-content feedstock for powder injection molding, comprising mixing metal powder and catalytic degreasing binder at a mass ratio of 120-130:5-15 and then densifying.

[0023] The metal powder includes copper-containing powder, and the mass fraction of copper powder in the copper-containing powder is 95-100%. Since the method of the present application is specifically for high-copper-content feedstock, the metal powder used in the method of the present application can be pure copper powder with 100% copper powder, or copper-containing alloy powder with copper content ≥95% and copper content not equal to 100%.

[0024] Since the copper content of pure copper powder is the highest, the deformation is more easily caused by the self-weight during the degreasing. In order to better reflect the advantages of the present application, the following examples are exemplified with pure copper powder, but should not be regarded as a limitation that the present application is only applicable to pure copper powder feedstock.

[0025] The copper powder includes first particle size powder, second particle size powder and third particle size powder, and the particle size relationship is: first particle size powder>second particle size powder>third particle size powder, the third particle size powder is near-spherical nano powder, the first particle size powder and the second particle size powder are both spherical micron powder, and the particle size of the first particle size powder satisfies D 50 =5.5-6.5 μm.

[0026] By setting three different particle sizes of copper powder as raw materials, the copper powder in the feedstock has at least two different particle sizes and possibly two different shapes, such as spherical and near-spherical. When the feedstock is used for powder injection molding, the multiple particle size combinations and shape combinations of copper powder can fill gaps with each other in the structure, thereby achieving efficient and stable control of the shape of the part.

[0027] However, the deformation degree of the high-copper-content feedstock varies greatly according to the actual situation, and therefore how to select the shape and size of the copper powder is crucial to preventing the high-copper-content feedstock from deforming in the powder injection molding process. The applicant has found through long-term research that when the largest particle size in the copper powder meets D 50 =5.5-6.5 μm, and another two kinds of copper powder with a smaller particle size than the first particle size powder are used, the deformation of the feedstock during the debinding process can be effectively prevented.

[0028] Further, the applicant has found through research that by further controlling the particle sizes of the second particle size powder and the third particle size powder, the deformation of the feedstock during the debinding process can be further optimized.

[0029] In an optional embodiment, the particle size of the second particle size powder meets D 50 =3.5-4.5 μm, and the particle size of the third particle size powder meets D 50 =95-105 nm.

[0030] Preferably, the particle size of the first particle size powder meets D 50 =5.99 μm, the particle size of the second particle size powder meets D 50 =3.88 μm, and the particle size of the third particle size powder meets D 50 =100 nm.

[0031] In an optional embodiment, the copper powder has a higher content of the powder with a larger D 50 particle size.

[0032] In an optional embodiment, the copper powder is composed of the first particle size powder, the second particle size powder and the third particle size powder, and the mass ratio of the first particle size powder, the second particle size powder and the third particle size powder is 60-65:32-40:1-3.

[0033] Preferably, the mass ratio of the first particle size powder, the second particle size powder and the third particle size powder is 62:36:2.

[0034] It should be further noted that the third particle size powder is a nano-powder with an extremely small particle size, and the technical requirements for preparing spherical nano-powder are high, and therefore most of the nano-powder is nearly spherical.

[0035] By using a smaller proportion of the third particle size powder, which is nearly spherical nano-pure copper powder, the microstructure of the sintered product can be refined, the density and performance of the sintered product are improved, and the cost of the pure copper feedstock is reduced.

[0036] In addition to the selection of the raw material of the copper powder, the catalytic debinding binder is another factor that can improve the shape retention capability of the feedstock.

[0037] In an optional embodiment, the catalytic debinding binder comprises polyoxymethylene (POM), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), paraffin wax (PW), stearic acid (SA) and triethanolamine (TEA).

[0038] The catalytic debinding binder used in the present application is a multi-component low-molecular-weight polymer that can assist copper powder in maintaining shape and avoiding deformation during powder injection molding. In addition, the present application uses triethanolamine to compound with other materials, which can effectively reduce the thermal decomposition of polyoxymethylene during mixing to ensure that the prepared feedstock has good rheological properties.

[0039] At the same time, the feedstock powder prepared by screening copper powder raw materials and compounding catalytic debinding binder has high loading capacity, which can reduce shrinkage and deformation and improve the dimensional accuracy of the product parts. The feedstock has low viscosity and good flowability within the injection temperature range, which is conducive to smooth mold filling without defects.

[0040] The mass ratio of polyoxymethylene (POM), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), paraffin wax (PW), stearic acid (SA) and triethanolamine (TEA) is 75-85:6-10:4-8:2-6:0.1-2:0.1-2.

[0041] Preferably, the mass ratio of polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, paraffin wax, stearic acid and triethanolamine is 80:8:6:4:1:1.

[0042] In an optional embodiment, during the mixing reaction process, the oxygen content in the mixer is <1000 ppm, the mixing temperature is 173-177°C, the mixer speed is 30-50 rpm, and the mixing time is 0.5-1.5 h.

[0043] It can be understood that controlling the oxygen content in the mixer can be achieved by blowing out the oxygen in the mixer with sufficient inert gas. The inert gas can be argon or other gases that do not react with the raw materials. By controlling the volume fraction of oxygen in the mixer to be <1000 ppm, the oxidation of copper during the preparation of the feedstock can be prevented.

[0044] Preferably, the mixing temperature is 175°C, the mixer speed is 40 rpm, and the mixing time is 1 h.

[0045] In an optional embodiment, during the mixing process, in order to ensure uniform dispersion of the metal powder and the catalytic debinding binder, the metal powder is first added to the mixer, and then the catalytic debinding binder is added.

[0046] Preferably, in order to ensure the mixing effect, the metal powder and the catalytic debinding binder are both added to the mixer when the mixer is at the mixing temperature.

[0047] Preferably, when the temperature of the internal mixer reaches the internal mixing temperature, the metal powder is first added into the internal mixer, and then the first internal mixing speed is set to preheat the metal powder; when the temperature of the internal mixer reaches the internal mixing temperature again, the catalytic debinding binder is first added into the internal mixer, and then the first internal mixing speed is set to preheat the catalytic debinding binder; when the temperature of the internal mixer reaches the internal mixing temperature once again, the speed is set to the internal mixing speed, wherein the first internal mixing speed is 10-20 rpm.

[0048] In an optional embodiment, the mass ratio of the metal powder to the catalytic debinding binder is 125:11.

[0049] In a second aspect, the present application provides a high-copper-content feedstock for powder injection molding, which is prepared by the preparation method of any one of the preceding embodiments.

[0050] In an optional embodiment, the feedstock is a pure copper feedstock, the viscosity of the feedstock at 175℃ is 85-95 Pa.S, the viscosity is relatively low, and the flowability is good, which is conducive to the smooth filling without defects; the oxygen content is ≤0.2 wt%, the copper powder in the feedstock is almost not oxidized, and the quality of the feedstock is high; the loading capacity is ≤65%, the feedstock of the present application has a relatively high loading capacity under the condition of having a relatively good flowability, which is conducive to the efficient production of powder injection molding.

[0051] In a third aspect, the present application provides an application of the preparation method of any one of the preceding embodiments to preventing the deformation of the feedstock in the process of powder injection molding.

[0052] Example 1

[0053] The present embodiment provides a pure copper feedstock for powder injection molding, and the preparation method thereof is as follows:

[0054] S01, the copper powders with three particle sizes are prepared according to the mass ratio of the first particle size powder, the second particle size powder and the third particle size powder is 62:36:2, and are placed on a double planetary mixer for fully mixing for 6 hours to ensure that the three kinds of copper powders are uniformly mixed.

[0055] The particle size of the first particle size powder satisfies D 50 = 5.99 μm, the particle size of the second particle size powder satisfies D 50 = 3.88 μm, and both are spherical micron powders; the particle size of the third particle size powder satisfies D 50 = 100 nm, and is a near-spherical nanometer powder.

[0056] S02, the above raw materials are mixed according to the mass ratio of polyformaldehyde, high-density polyethylene, ethylene-vinyl acetate copolymer, paraffin, stearic acid and triethanolamine is 80:8:6:4:1:1 to prepare a catalytic debinding binder.

[0057] S03, 440 g of the catalytic debinding binder of step S02 is weighed into a clean plastic cup, and 5000 g of the copper powder prepared in step S01 is weighed into another clean plastic cup, and then the two plastic cups are placed in the mixing area of the internal mixer, high-purity argon is filled in the mixing area of the internal mixer, and the internal mixer is preheated.

[0058] When the internal mixing temperature reaches 175°C and the oxygen content in the internal mixer is less than 1000 ppm, the copper powder prepared in step S01 is poured into the internal mixer, the rotating speed is set to 15 rpm, and the preheating of the copper powder is continued.

[0059] When the internal mixing temperature reaches 175°C again, the catalytic debinding binder is poured into the internal mixer, the rotating speed is set to 15 rpm, and the preheating of the copper powder and the catalytic debinding binder is continued.

[0060] When the internal mixing temperature reaches 175°C again, the rotating speed is set to 40 rpm, and after 1 hour of internal mixing, the heating is stopped, and the granules are taken out after cooling to obtain pure copper feedstock for powder injection molding.

[0061] It is tested that the viscosity of the feedstock provided by the embodiment at 175°C is 90 Pa.S, and the oxygen content is 0.19 wt%.

[0062] The pure copper parts prepared by powder injection molding sintering using the feedstock of the embodiment have a dimensional accuracy of ±1% / in, a density of 98.7%, a tensile strength of 239 MPa, and an elongation of 58%, and the microstructure morphology thereof is as shown in Figure 1 Due to the addition of nanoscale copper powder in the embodiment, the microstructure of the pure copper parts is refined.

[0063] Example 2

[0064] The embodiment provides a pure copper feedstock for powder injection molding, and the preparation method thereof is as follows:

[0065] S01, the copper powder with three particle sizes is prepared according to the mass ratio of the first particle size powder, the second particle size powder and the third particle size powder being 62:36:2, and is placed on a double planetary mixer for sufficient mixing for 6 hours to ensure uniform mixing of the three kinds of copper powder.

[0066] Among them, the particle size of the first particle size powder satisfies D 50 = 5.99 μm, the particle size of the second particle size powder satisfies D 50 = 3.88 μm, and both are spherical micropowder; the particle size of the third particle size powder satisfies D 50 = 100 nm, which is a near-spherical nanometer powder.

[0067] S02, the catalytic debinding binder was prepared by mixing the above raw materials in the mass ratio of polyformaldehyde, high density polyethylene, ethylene-vinyl acetate copolymer, paraffin wax, stearic acid and triethanolamine being 80:8:6:4:1:1.

[0068] S03, 440g of the catalytic debinding binder prepared in step S02 was weighed into a clean plastic cup, and 5000g of the copper powder prepared in step S01 was weighed into another clean plastic cup, and then the two plastic cups were placed in the mixing area of the internal mixer, high-purity argon was filled in the mixing area of the internal mixer, and the internal mixer was preheated.

[0069] When the internal mixing temperature reached 176°C and the oxygen content in the internal mixer was less than 1000 ppm, the copper powder prepared in step S01 was poured into the internal mixer, the rotation speed was set to 15 rpm, and the copper powder was continuously preheated.

[0070] When the internal mixing temperature reached 176°C again, the catalytic debinding binder was poured into the internal mixer, the rotation speed was set to 15 rpm, and the copper powder and the catalytic debinding binder were continuously preheated.

[0071] When the internal mixing temperature reached 176°C again, the rotation speed was set to 40 rpm, and after 1 hour of internal mixing, the heating was stopped, and the granules were taken out after cooling to obtain the pure copper feedstock for powder injection molding.

[0072] Comparative Example 1

[0073] The comparative example provides a pure copper feedstock for powder injection molding, and the preparation method is similar to that of Example 2, the difference is only that the internal mixing temperature in step S03 is adjusted from 175°C to 180°C.

[0074] Test results show that the viscosity of the feedstock provided by the comparative example at 180°C is 105 Pa.S, and the oxygen content is 0.21wt%.

[0075] The pure copper parts prepared by using the feedstock have a dimensional accuracy of ±1.5% / in, a density of 96.8%, a tensile strength of 228 MPa, and an elongation of 45%.

[0076] Comparative Example 2

[0077] The comparative example provides a pure copper feedstock for powder injection molding, and the preparation method is similar to that of Example 2, the difference is only that the internal mixing temperature in step S03 is adjusted from 175°C to 172°C.

[0078] Test results show that the viscosity of the feedstock provided by the comparative example at 172°C is 107 Pa.S, and the oxygen content is 0.21wt%.

[0079] The pure copper part prepared by using the feed has a dimensional accuracy of ±1.5% / in, a density of 95.2%, a tensile strength of 216 MPa and an elongation of 39%.

[0080] Comparative Example 3

[0081] The comparative example provides a pure copper feed for powder injection molding, and the preparation method is similar to that of Example 2, and the difference is only that the S02 step is different, and the specific steps are as follows:

[0082] S02, the catalytic debinding binder is prepared by mixing the above raw materials according to the mass ratio of polyformaldehyde, high-density polyethylene, ethylene-vinyl acetate copolymer, paraffin and stearic acid is 80:8:6:4:2.

[0083] Test results show that the viscosity of the feed provided by the comparative example at 175°C is 108 Pa.S, and the oxygen content is 0.22wt%.

[0084] The pure copper part prepared by using the feed has a dimensional accuracy of ±1.5% / in, a density of 95.2%, a tensile strength of 216 MPa and an elongation of 39%.

[0085] Comparative Example 4

[0086] The comparative example provides a pure copper feed for powder injection molding, and the preparation method is similar to that of Example 2, and the difference is only that the S01 step is different, and the specific steps are as follows:

[0087] S01, all the copper powder is the second particle size powder, the particle size of the second particle size powder meets D 50 =3.88 μm, and is a spherical micron powder.

[0088] Test results show that the viscosity of the feed provided by the comparative example at 175°C is 102 Pa.S, and the oxygen content is 0.22wt%.

[0089] The pure copper part prepared by using the feed has a dimensional accuracy of ±1.5% / in, a density of 95.2%, a tensile strength of 216 MPa and an elongation of 39%.

[0090] Comparative Example 5

[0091] The comparative example provides a pure copper feed for powder injection molding, and the preparation method is similar to that of Example 2, and the difference is only that the S01 step is different, and the specific steps are as follows:

[0092] S01, all the copper powder is the first particle size powder, the particle size of the first particle size powder meets D 50 =5.99 μm, and is a spherical micron powder.

[0093] The feeding provided by the comparative example has a viscosity of 108 Pa.S at 175℃ and an oxygen content of 0.19wt%.

[0094] The pure copper part prepared by using the feeding has a dimensional accuracy of ±2% / in, a density of 93.6%, a tensile strength of 211 MPa, and an elongation of 34%.

[0095] Comparative Example 6

[0096] The comparative example provides a pure copper feeding for powder injection molding, and the preparation method is similar to that of Example 2, except that the S01 step is different, specifically as follows:

[0097] S01, the first particle size powder and the second particle size powder are prepared in a mass ratio of 62:38 and are placed in a double planetary mixer for sufficient mixing for 6 hours to ensure uniform mixing of the two copper powders.

[0098] The first particle size powder has a particle size of D 50 = 5.99 μm, and the second particle size powder has a particle size of D 50 = 3.88 μm, and both are spherical micron powders.

[0099] The feeding provided by the comparative example has a viscosity of 108 Pa.S at 175℃ and an oxygen content of 0.19wt%.

[0100] The pure copper part prepared by using the feeding has a dimensional accuracy of ±2% / in, a density of 93.6%, a tensile strength of 211 MPa, and an elongation of 34%.

[0101] Comparative Example 7

[0102] The comparative example provides a pure copper feeding for powder injection molding, and the preparation method is similar to that of Example 2, except that the S03 step is different, specifically as follows:

[0103] The feeding provided by the comparative example has a viscosity of 108 Pa.S at 175℃ and an oxygen content of 0.19wt%.

[0104] The pure copper part prepared by using the feeding has a dimensional accuracy of ±2% / in, a density of 93.6%, a tensile strength of 211 MPa, and an elongation of 34%.

[0105] Test Example 1

[0106] The feeding prepared in Examples 1-2 and Comparative Examples 1-7 is subjected to viscosity testing and oxygen content testing, and the results are shown in Table 1, wherein the viscosity testing method refers to GB / T 10247, and the oxygen content testing refers to GB / T 511.8.

[0107] Further, the feedstocks prepared in Examples 1-2 and Comparative Examples 1-7 were subjected to powder injection molding experiments (preparation parameters including: injection temperature 173-177℃, injection pressure 70-80MPa, holding pressure 70-80MPa, sintering temperature 950-1000℃), and the same pure copper parts were obtained, and the properties of the pure copper parts were also shown in Table 1, wherein the density test method refers to GB / T 5163, the tensile strength test method refers to GB / T 228.1-2021, and the elongation test method refers to GB / T 228.1-2021.

[0108] Table 1 Properties of the feedstocks and the properties of the prepared parts

[0109]

[0110]

[0111] As can be seen from Table 1, the pure copper feedstock provided by the present application has low viscosity, low oxygen content and high loading capacity, and the copper-containing material prepared by powder injection molding has improved tensile strength, elongation and density. The viscosity, elongation and other properties of Comparative Example 1 are significantly lower than those of Example 1 due to the excessively high mixing temperature, which causes part of the binder to volatilize. The viscosity, elongation and other properties of Comparative Example 2 are significantly lower than those of Example 1 due to the low mixing temperature and uneven mixing. The viscosity, elongation and other properties of Comparative Example 3 are significantly lower than those of Example 1 due to the absence of triethanolamine, which causes excessive volatilization of polyformaldehyde. The viscosity, density, elongation and other properties of Comparative Example 4 are significantly lower than those of Example 1 due to the use of a single particle size powder D50=3.88μm. The viscosity, density, elongation and other properties of Comparative Example 5 are significantly lower than those of Example 1 due to the use of a single particle size powder D50=5.99μm. The viscosity, density, elongation and other properties of Comparative Example 6 are significantly lower than those of Example 1 due to the absence of nano-powder D50=100nm. The viscosity, elongation and other properties of Comparative Example 2 are significantly lower than those of Example 1 due to the low mixing temperature and uneven mixing.

[0112] The tensile properties of the pure copper parts of Examples 1 and 2 are shown in Table 2, and it can be seen from Table 2 that the pure copper parts prepared from the feedstocks of the present application have good tensile properties. Figure 2 Figure 2 The tensile properties of the pure copper parts of Examples 1 and 2 are shown in Table 2, and it can be seen from Table 2 that the pure copper parts prepared from the feedstocks of the present application have good tensile properties.

[0113] The above is only a preferred embodiment of the present application and is not intended to limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.​

Claims

1. A process for the preparation of a high copper content feedstock for powder injection moulding, characterised in that, The metal powder is mixed with the catalytic debinding binder in a mass ratio of 120-130:5-15 in a closed mixer; The metal powder is copper-containing powder, and the mass fraction of copper powder in the copper-containing powder is 95-100%; The copper powder comprises a first particle size powder, a second particle size powder and a third particle size powder, and the particle size size relationship is: first particle size powder > second particle size powder > third particle size powder, the third particle size powder is a near-spherical nano powder, the first particle size powder and the second particle size powder are both spherical micron powders, and the particle size of the first particle size powder satisfies D 50 = 5.5~6.5μm; The catalytic debinding binder comprises polyformaldehyde, high-density polyethylene, ethylene-vinyl acetate copolymer, paraffin wax, stearic acid and triethanolamine; The mass ratio of the polyformaldehyde, high-density polyethylene, ethylene-vinyl acetate copolymer, paraffin wax, stearic acid and triethanolamine is 75-85:6-10:4-8:2-6:0.1-2:0.1-2; The particle size of the second particle size powder satisfies D 50 = 3.5 to 4.5 μm, and the particle size of the third particle size powder satisfies D 50 = 95 to 105 nm. The copper powder is composed of first particle size powder, second particle size powder and third particle size powder, and the mass ratio of the first particle size powder, second particle size powder and third particle size powder is 60-65:32-40:1-3.

2. The production method according to claim 1, characterized by, The mass ratio of the polyformaldehyde, high-density polyethylene, ethylene-vinyl acetate copolymer, paraffin wax, stearic acid and triethanolamine is 80:8:6:4:1:

1.

3. The preparation method according to claim 1, characterized in that The particle diameter of the first particle diameter powder satisfies D 50 = 5.99 μm, the particle diameter of the second particle diameter powder satisfies D 50 = 3.88 μm, and the particle diameter of the third particle diameter powder satisfies D 50 = 100 nm.

4. The production method according to claim 3, characterized by, The mass ratio of the first particle size powder, second particle size powder and third particle size powder is 62:36:

2.

5. The preparation method according to claim 1, characterized in that During the mixing process, the oxygen content in the mixer is <1000 ppm, the mixing temperature is 173-177°C, the mixer speed is 30-50 rpm, and the mixing time is 0.5-1.5 h.

6. The production method according to claim 5, wherein The mixing temperature is 175°C, the mixer speed is 40 rpm, and the mixing time is 1 h.

7. The preparation method according to claim 5, characterized in that During the mixing process, the metal powder is first added to the mixer, and then the catalytic debinding binder is added; The metal powder and the catalytic debinding binder are both added to the mixer when the mixer reaches the mixing temperature.

8. The preparation method according to claim 7, characterized in that When the temperature of the mixer reaches the mixing temperature, the metal powder is first added to the mixer, and then a first mixing speed is set to preheat the metal powder; when the temperature of the mixer reaches the mixing temperature again, the catalytic debinding binder is first added to the mixer, and then the first mixing speed is set to preheat the catalytic debinding binder; when the temperature of the mixer reaches the mixing temperature again, the mixer speed is set to the mixing speed; The first mixing speed is 10-20 rpm.

9. The method of claim 1, wherein, The mass ratio of the metal powder to the catalytic debinding binder is 125:

11.

10. A high copper content feedstock for powder injection molding, characterized in that, Prepared by the preparation method of any one of claims 1-9.

11. The feed of claim 10, wherein, The feedstock is pure copper feedstock, the viscosity of the feedstock at 175°C is 85-95 Pa.S, the oxygen content is ≤0.2 wt%, and the loading capacity is ≤65%.

Images