AgCuNi-based electric contact material and preparation method thereof

Abstract

The invention relates to the technical field of new alloy electric contact materials, and particularly discloses an AgCuNi-based electric contact material and a preparation method thereof.The preparation method comprises the steps that firstly, powder A and powder B are mixed to prepare AgCuNi-based alloy powder, the AgCuNi-based alloy powder and a binder are mixed and granulated to obtain feed, then a green body is obtained in an injection molding machine, and the green body is subjected to hot pressing to obtain the AgCuNi-based electric contact material. And finally, the green body is sequentially subjected to degreasing, hydrogen sintering densification and solution treatment, and the AgCuNi-based material is obtained. The chemical component of the powder A is Ag-xCu-yNi, x ranges from 0.5 wt% to 3 wt%, y ranges from 1 wt% to 2 wt%, the chemical component of the powder B is Bi-zSn, z ranges from 40 wt% to 60 wt%, and the powder B accounts for 10%-15% of the AgCuNi-based alloy powder. On the basis of the powder injection molding technology, liquid-phase Bi-Sn alloy doping is adopted in an AgCuNi matrix, the microstructure of the material is improved through the synergistic effect of hydrogen sintering and solution treatment, the AgCuNi-based electric contact material high in hardness and strength and good in corrosion resistance is obtained, and meanwhile the method has the advantages of being simple in process, low in production cost, suitable for mass production and the like.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of new alloy electric contact materials, and in particular to an AgCuNi-based electric contact material and a preparation method thereof. BACKGROUND

[0002] Silver-based electric contact materials are important electronic device materials and are widely used in electric contact contacts, conductive brushes, conductive rings, electric commutating sheets, potentiometers and other key electronic circuit components, and bear important purposes such as electric signal transmission, electric signal control, electric current commutation, electric current interruption and electric current shunting. The mechanical and electrical properties of the electric contact materials directly affect the service reliability, service stability, service precision and service life of electronic circuits and electrical devices.

[0003] Pure silver is a metal material with the highest electrical conductivity and thermal conductivity, and has the characteristics of easy processing and good plasticity, and is widely used in electronic component electric contact materials. However, in a high-temperature, high-humidity and sulfur-containing atmosphere, a sulfide film is easily formed on the surface of pure silver, which leads to an increase in the surface resistance of the contact material and unstable electric contact signals. At the same time, the mechanical properties of pure silver are poor, and the wear resistance and hardness are low. When applied to sliding electric contact materials, the degree of material surface friction and wear is too large, resulting in unstable electric current and electric signals, and high electric signal transmission noise. These reasons make it difficult to meet the use environment of modern electronic components.

[0004] In order to improve the performance of pure silver electric contact materials, control costs and reduce the amount of precious metal materials, the addition of a certain amount of inexpensive metal to form an alloy material can effectively improve the wear resistance and arc resistance of silver-based electric contact materials, and improve the service life and stability of the materials. Among them, the representative material AgCuNi is born on the basis of AgCu materials and AgNi materials. AgCu electric contact materials have the advantages of good electrical conductivity, thermal conductivity and elongation, and relatively low price, but have segregation tendency. The addition of an appropriate amount of Ni can significantly reduce segregation and also improve the corrosion resistance and wear resistance of the alloy. However, AgCuNi alloy materials have the problems of low strength, low hardness, poor corrosion resistance and short service life in actual engineering applications. In order to further improve the comprehensive performance of AgCuNi alloy, researchers in various countries have mainly made the following two attempts to improve the performance of AgCuNi electric contact materials. One is the research on chemical composition, and the selection of appropriate additives to improve the material; the other is the research on the preparation method, and the improvement of the preparation method to improve the material performance.

[0005] Patent application with publication number CN 115896530 A discloses a high-performance AgCuNi composite material and a preparation method thereof. In the material, Cu is 1-25% by mass percentage, Ni is 0.1-0.8% by mass percentage, 0.01-3.0% of additive elements, and the balance is Ag. The additive elements are any one or several of Sn, In, W, Mo, Ce, La, Y, V, Ga, Ge, Dy, Co, Zn, Mo2O3, WO3, WC, GeO2, Dy2O3, SnO2, ZrO, and ZnO elements. The additive elements are added to improve the resistance welding performance and wear resistance of the material and reduce the material damage caused by the adhesion loss of the commutator of a direct current motor. However, in this method, the differences between metal elements and metal oxides are large, and it is difficult to achieve the same effect. At the same time, the preparation process includes extrusion and rolling, which is not conducive to mass production.

[0006] Patent application with publication number CN 108149057 A discloses an AgCuNiV alloy material and a preparation method thereof. The weight percentage composition of the AgCuNiV alloy material is: Ag 66.5%-89.1%, Cu 9.5%-27.72%, Ni 0%-1.98%, and V 1.0%-5.0%. By preparing AgCuNi alloy powder, mixing the AgCuNi alloy powder and V powder, and using spark plasma sintering technology to prepare AgCuNiV alloy, the microstructure is fine and uniform, and there is no segregation, which can effectively ensure the reliability of the electrical contact material in radar electronic devices, and obtain an electrical contact material with uniform composition and defect-free surface. However, this method requires special equipment and has high cost, which is difficult to use for mass production and is not conducive to popularization. Therefore, how to seek optimization in composition design and preparation process to prepare high-performance AgCuNi-based electrical contact material with high hardness, high strength, and good corrosion resistance is a problem to be solved. SUMMARY

[0007] To overcome the above shortcomings, the present application provides an AgCuNi-based electrical contact material and a preparation method thereof. The powder injection molding technology is used, and methods such as liquid phase Bi-Sn alloy doping, hydrogen sintering, and solid solution treatment are used to improve the microstructure of the material, obtain AgCuNi-based electrical contact material with high hardness, high strength, and good corrosion resistance, and have the advantages of simple process, low production cost, and suitable for mass production. The specific technical scheme is as follows: A preparation method of an AgCuNi-based electrical contact material, comprising the following steps: (1) mixing powder A and powder B to obtain AgCuNi-based alloy powder; the chemical composition of the powder A is Ag-xCu-yNi, x is 0.5-3wt.%, y is 1-2wt.%; the chemical composition of the powder B is Bi-zSn, z is 40-60wt.%, the mass percentage of the powder B in the AgCuNi-based alloy powder is 10-15%; (2) mixing the AgCuNi-based alloy powder obtained in step (1) with a binder to obtain a feedstock; (3) injection molding the feedstock to obtain a green body, and debinding the green body to obtain a debound body; (4) sequentially sintering and densifying the debound body to obtain a sintered body, and solid solution treating the sintered body to obtain an AgCuNi-based electrical contact material; The sintering and densifying process is as follows: placing the debound body in a hydrogen sintering furnace, first vacuumizing, then passing hydrogen, and heating to 700-900 DEG C at a heating rate of 2-5 DEG C / min, keeping the temperature for 1-2h, and cooling to room temperature in the furnace and discharging.

[0008] The technical scheme of the application works as follows: (1) Chemical composition optimization: silver has the best electrical conductivity among all metals and excellent processing performance. However, silver has low hardness and low strength, and poor wear resistance. In order to improve the hardness and strength of the material, Cu element is added. AgCu alloy has good mechanical properties. Ag and Cu elements are limitedly soluble, and in the AgCu binary electrical contact material, the mass fraction of copper element is usually between 3-28%. At this time, the hardness and strength of the silver-based alloy contact are improved compared with pure silver, but intermetallic compounds are easily generated in the alloy, which reduces the corrosion resistance. Therefore, in the present application, the addition amount of Cu is controlled to be 0.5-3wt.%, the second phase generated by segregation is reduced, the corrosion resistance is improved, and a small amount of Ni is added. Ni and Cu can form a continuous solid solution during solidification, which has a high melting point and can improve the strength and hardness, and improve the wear resistance and arc resistance. In addition, the high proportion (10-15wt.%) of low melting point liquid Bi-Sn alloy is introduced for the first time, which not only reduces the porosity, but also increases the interface bonding strength and reduces the thermal stress, so as to finally improve the strength and hardness of the material. In the sintering process, Bi-Sn alloy forms a liquid phase, which is distributed around the Ag matrix, increases the wettability between the matrix elements Ag, Cu and Ni, improves the alloy composition distribution, reduces the formation of pores, and obtains high density. At the same time, the presence of liquid phase is beneficial to the penetration of each element at the interface, which improves the grain boundary bonding force, avoids the cracking of the material along the grain boundary under stress, and further improves the strength and hardness of the material.

[0009] (2) Preparation method: 1) The first time the metal injection molding technology (MIM) is introduced into the preparation of AgCuNi alloy products, reducing the production cost, solving the problem of mass production. MIM can quickly and accurately convert design ideas into products, and can use one mold with multiple holes to carry out mass production with high efficiency. The technology involves injection molding, powder metallurgy, material processing and other multidisciplinary comprehensive cross, which injects polymer binder and metal powder into the mold to obtain a specific shape of the blank, and then carries out debinding and sintering, thereby preparing a part with certain density, size accuracy and complex shape. In essence, MIM is a near-net shaping method, which has the characteristics of high performance, low cost, uniform density, etc., especially in the preparation of thin-walled and complex structural parts, which has incomparable advantages over traditional processes.

[0010] 2) The polyformaldehyde binder system is used to reduce the impurity content. The binder plays an important role in MIM, which is used to balance and ensure the good flowability of the injection material and the high strength of the injection part. The commonly used binder system in MIM is a wax-based system, but due to its low solvent debinding efficiency, the carbon content of the obtained product is high. The carbon content has a great influence on the corrosion resistance of the electrical contact material, and too high carbon content will cause the appearance of carbide, affecting the density and corrosion resistance. Therefore, the polyformaldehyde binder system is selected, which provides the flowability of the feed material, high-density polyethylene and polypropylene as the skeleton material, which provides the strength of the feed material, and ethylene-propylene copolymer rubber as the additive. Through the appropriate amount of addition, the flowability and strength of the feed material are balanced to ensure that the mold micro channel is fully filled during injection, and the metal powder and the binder are separated; The method of catalytic debinding is used, which can well remove the polyformaldehyde molecules in the high-temperature acidic environment, and the thermal debinding is used to remove the skeleton phase and the additive binder. By controlling the corresponding heating rate and holding time, it is ensured that the organic binder is completely removed, and the residual organic binder is avoided to form carbide in the sintering process, causing the increase of carbon content.

[0011] 3) Hydrogen sintering, control the density and impurity content. Sintering is a very important process in MIM, which plays a decisive role in the organization, density performance and chemical uniformity of the product. In the preparation of AgCuNi alloy by powder metallurgy method, vacuum sintering or plasma discharge sintering is usually used. Vacuum sintering is not conducive to the removal of impurities, which leads to a decrease in density and affects the performance, while plasma discharge sintering has the problems of high cost and is not conducive to mass production. The method of hydrogen sintering is used in the present invention, which first does not need to use special equipment, greatly reducing the production cost, and secondly, using hydrogen to reduce the residual C and O in the debound blank can well reduce the impurity content of the alloy, thereby obtaining a high-density sintered blank. The reduction of porosity avoids the phenomenon of stress concentration, which is conducive to improving the strength and hardness of the material.

[0012] 4) Solution treatment, improving microstructure. After sintering process, due to the effect of non-uniform temperature field and non-equilibrium solidification, a small amount of Cu-rich second phase is still generated in the alloy, which will cause second phase corrosion and will not be conducive to the improvement of corrosion resistance. The present application uses solution treatment process to heat the alloy to a high temperature single-phase zone and keep constant temperature, so that the Cu-rich phase is fully dissolved into the solid solution, and then rapidly cooled to obtain a supersaturated solid solution, which can not only improve the strength, but also achieve the purpose of improving the corrosion resistance. According to the ASTM B117 salt spray test standard, the salt spray resistance time can reach more than 96h. The inventor found that the solution process has a great influence on the performance of the alloy. If the solution temperature is higher than 500℃ or the holding time is longer than 2h, the Ag-based grains will grow significantly and the strength of the alloy will decrease. If the solution temperature is lower than 400℃ or the holding time is less than 1h, the Cu-rich phase cannot be fully dissolved into the matrix, and the strength and corrosion resistance of the alloy cannot be improved. Therefore, the inventor determines the process parameters of the solution treatment through a large number of experiments. Under the above process parameters, a material with excellent performance can be obtained.

[0013] Preferably, in the preparation method of the AgCuNi-based electrical contact material, the impurity elements include at least one of C, O, P and S in mass percentage, the content of C is ≤0.02wt.%, the content of O is ≤0.02wt.%, the content of P is ≤0.02wt.% and the content of S is ≤0.02wt.%, and the total amount of the impurity elements is ≤0.08wt.%.

[0014] Preferably, in the preparation method of the AgCuNi-based electrical contact material, the solution treatment process is as follows: the sintered blank is placed in an argon atmosphere protection, heated to 400-500℃ at a heating rate of 2-5℃ / min, and held for 1-2h, and then cooled to room temperature in a quenching oil.

[0015] Preferably, in the preparation method of the AgCuNi-based electrical contact material, the average particle size of the powder A is 1-3μm, and the average particle size of the powder B is 0.2-0.5μm, which are prepared by gas atomization method or water-gas combined atomization method.

[0016] Preferably, in the preparation method of the AgCuNi-based electrical contact material, in step (1), the powder A and the powder B are placed in a mixer and mixed for 1-2h in a nitrogen environment.

[0017] Preferably, in the preparation method of the AgCuNi-based electrical contact material, the binder in step (2) is composed of the following components by mass percentage: polyformaldehyde 60-75%, high-density polyethylene 10-15%, polypropylene 10-15%, ethylene-propylene copolymer rubber 3-5%, and stearic acid 2-5%; and the mass ratio of the binder to the AgCuNi-based alloy powder is 7.1-8.6%:91.4-92.9%.

[0018] Preferably, in the preparation method of the AgCuNi-based electrical contact material, the mixing process parameters are as follows: the mixing temperature is 160-200°C, and the mixing time is 1-2h.

[0019] Preferably, in the preparation method of the AgCuNi-based electrical contact material, the injection process parameters are as follows: the injection temperature is 160-190°C, the injection pressure is 80-160MPa, and the mold temperature is 30-60°C.

[0020] Preferably, in the preparation method of the AgCuNi-based electrical contact material, in step (3), the debinding process is divided into two steps of catalytic debinding and thermal debinding; the catalytic debinding process parameters are as follows: the flow rate of nitric acid is 1-4ml / min, the catalytic debinding temperature is 120-140°C, and the catalytic debinding time is 10-16h; and the thermal debinding process is as follows: in a vacuum debinding furnace, under the protection of an argon atmosphere, heating at a rate of 2-5°C / min to 400-500°C for 2-4h, and then cooling to room temperature in the furnace.

[0021] In another aspect, the application also provides an AgCuNi-based electrical contact material prepared by the above preparation method.

[0022] Preferably, in the AgCuNi-based electrical contact material, the relative density of the electrical contact material is ≥99%, the hardness of the electrical contact material is ≥155Hv, the strength of the electrical contact material is ≥500MPa, and the salt spray resistance time is ≥96h.

[0023] Compared with the prior art, the application has the following beneficial effects: 1. The AgCuNi-based electrical contact material prepared by the preparation method has a hardness and strength improved by more than 20% compared with conventional AgCuNi materials, and has excellent comprehensive performance.

[0024] 2. The preparation method is simple, MIM technology is used to replace the rolling and extrusion in the conventional preparation process, the process steps are reduced, batch production is easy, no expensive elements are added, the raw material cost and production cost are low.

[0025] 3. The application is based on the powder injection molding technology, a low-melting-point Bi-Sn alloy is doped in an AgCuNi matrix, and the synergistic effect of hydrogen sintering and solid solution treatment is used to improve the microstructure of the material, so as to obtain an AgCuNi-based electrical contact material with high hardness, high strength and good corrosion resistance, and the process is simple, the production cost is low, and the material is suitable for mass production, which can well meet the commercial demand and is very suitable for preparing AgCuNi electrical contact products. BRIEF DESCRIPTION OF DRAWINGS

[0026] 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 embodiment description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative labor on the basis of these drawings.

[0027] Figure 1 SEM picture of the sample of embodiment 2 of the present application. DETAILED DESCRIPTION

[0028] The specific embodiments of the present application will be described in detail below, but it should be understood that the protection scope of the present application is not limited by the specific embodiments. Unless otherwise defined, all professional terms used below have the same meaning as generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing the specific embodiments and are not intended to limit the protection scope of the present application. Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0029] Embodiment 1 The present embodiment provides a preparation method of an AgCuNi-based electrical contact material, comprising the following steps: (1) Raw material preparation: 1.5 μm average particle size of gas atomized Ag-2wt.%Cu-1wt.%Ni powder and 0.3 μm average particle size of gas atomized Bi-40wt.%Sn powder are mixed in a mixer for 1 h under a nitrogen environment to prepare an AgCuNi-based alloy powder, wherein the mass percentage of Bi-40wt.%Sn in the AgCuNi-based alloy powder is 10%; (2) Preparation of binder: take polyformaldehyde (POM) 65%, high-density polyethylene (HDPE) 15%, polypropylene (PP) 15%, ethylene-propylene copolymer rubber (EPR) 3%, and stearic acid (SA) 2% to prepare a binder; (3) Preparation of feedstock: the binder and the alloy powder are mixed and granulated to prepare a feedstock according to a mass ratio of 7.7%:92.3%, the mixing temperature is 180°C, and the mixing time is 2h; (4) injection molding: using an injection molding machine to inject the feed into the mold cavity to obtain the product green body, the injection temperature is 160℃, the injection pressure is 110MPa, and the mold temperature is 60℃; (5) debinding: the product green body is first subjected to catalytic debinding, the nitric acid flow is 2ml / min, the catalytic debinding temperature is 120℃, and the catalytic debinding time is 16h, then hot debinding is carried out in a vacuum debinding furnace, heated to 500℃ at a heating rate of 3℃ / min for 2h, and then cooled to room temperature in the furnace; (6) sintering: the debound body is placed in a hydrogen atmosphere sintering furnace, heated to 800℃ at a heating rate of 3℃ / min, kept for 1h, and then cooled to room temperature in the furnace; (7) solid solution: the sintered body is placed in a heat treatment furnace, heated to 500℃ at a heating rate of 2℃ / min in an argon atmosphere, kept for 1h, and then cooled to room temperature in the quenching oil to obtain the AgCuNi-based electrical contact material.

[0030] The AgCuNi-based electrical contact material prepared in this embodiment has the following properties: the total amount of impurity elements is 0.08wt.%, the density is 99%, the hardness is 155Hv, the tensile strength is 500MPa, and the salt spray resistance time is 96h.

[0031] Example 2 This embodiment provides a preparation method of an AgCuNi-based electrical contact material, comprising the following steps: (1) raw material preparation: mixing 1.0μm average particle size gas atomized Ag-1.5wt.%Cu-1wt.%Ni powder and 0.4μm average particle size gas atomized Bi-48wt.%Sn powder in a mixer for 1h in a nitrogen environment to prepare AgCuNi-based alloy powder, wherein the mass percentage of Bi-48wt.%Sn in the AgCuNi-based alloy powder is 10%; (2) preparation of binder: taking polyformaldehyde (POM) 70%, high-density polyethylene (HDPE) 15%, polypropylene (PP) 10%, ethylene-propylene copolymer rubber (EPR) 3%, and stearic acid (SA) 2% to prepare a binder according to the mass percentage; (3) preparation of feed: mixing and granulating the binder and the alloy powder at a mass ratio of 8.6%:91.4% to prepare the feed, the mixing temperature is 180℃, and the mixing time is 2h; (4) injection molding: using an injection molding machine to inject the feed into the mold cavity to obtain the product green body, the injection temperature is 170℃, the injection pressure is 100MPa, and the mold temperature is 50℃; (5) Degreasing: the product green body is first subjected to catalytic degreasing, the nitric acid flow is 2 ml / min, the catalytic degreasing temperature is 130℃, and the catalytic degreasing time is 14 h, and then hot degreasing is carried out in a vacuum degreasing furnace, and in the protection of an argon atmosphere, heating to 500℃ at a heating rate of 3℃ / min for 2 h, and then cooling to room temperature in the furnace; (6) Sintering: the degreased body is placed in a hydrogen atmosphere sintering furnace, and heated to 900℃ at a heating rate of 3℃ / min, and held for 1 h, and then cooled to room temperature in the furnace and taken out; (7) Solid solution: the sintered body is placed in a heat treatment furnace, and heated to 450℃ at a heating rate of 2℃ / min in an argon atmosphere, and held for 2 h, and then cooled to room temperature in a quenching oil, to obtain an AgCuNi-based electrical contact material.

[0032] The AgCuNi-based electrical contact material prepared in this embodiment has the following properties: the total amount of impurity elements is 0.07wt.%, the density is 99.3%, the hardness is 162 Hv, the tensile strength is 520 MPa, and the salt spray resistance time is 98 h. The SEM image of the AgCuNi-based electrical contact material sample prepared in this embodiment is shown in Figure 1 As can be seen from the figure, the material only has AgCuNi solid solution and Bi-Sn alloy phase, the solid solution grain is small, there is no Cu-rich second phase, and the structure is uniformly distributed.

[0033] Example 3 The embodiment provides a preparation method of an AgCuNi-based electrical contact material, comprising the following steps: (1) Raw material preparation: 1.2μm average particle size of gas atomized Ag-1wt.%Cu-0.5wt.%Ni powder and 0.5μm average particle size of gas atomized Bi-50wt.%Sn powder are mixed in a mixer for 1h in a nitrogen environment to prepare AgCuNi-based alloy powder, wherein the mass percentage of Bi-50wt.%Sn in the AgCuNi-based alloy powder is 12%; (2) Preparation of binder: polyformaldehyde (POM) 75%, high-density polyethylene (HDPE) 10%, polypropylene (PP) 10%, ethylene-propylene copolymer rubber (EPR) 3%, and stearic acid (SA) 2% are taken to prepare a binder according to the mass percentage; (3) Preparation of feedstock: the binder and the alloy powder are mixed and granulated to prepare a feedstock according to a mass ratio of 7.1%:92.9%, the mixing temperature is 180℃, and the mixing time is 2h; (4) Injection molding: the feedstock is injected into a mold cavity by using an injection molding machine to obtain a product green body, the injection temperature is 180℃, the injection pressure is 80MPa, and the mold temperature is 60℃; (5) Degreasing: the green body of the product was first subjected to catalytic degreasing, the flow rate of nitric acid was 2 ml / min, the catalytic degreasing temperature was 120°C, and the catalytic degreasing time was 16 h, and then the product was subjected to thermal degreasing in a vacuum degreasing furnace, and was heated to 500°C at a heating rate of 3°C / min and was kept for 2 h, and then was cooled to room temperature in an argon atmosphere; (6) Sintering: the degreased body was placed in a hydrogen sintering furnace, and was heated to 850°C at a heating rate of 3°C / min, and was kept for 2 h, and was cooled to room temperature in the furnace and was taken out of the furnace; (7) Solid solution: the sintered body was placed in a heat treatment furnace, and was heated to 500°C at a heating rate of 2°C / min in an argon atmosphere, and was kept for 1 h, and was then cooled to room temperature in a quenching oil, to obtain the AgCuNi-based electrical contact material.

[0034] The AgCuNi-based electrical contact material prepared in this example had the following properties: the total amount of impurity elements was 0.08wt.%, the density was 99.1%, the hardness was 160 Hv, the tensile strength was 511 MPa, and the salt spray resistance time was 96 h.

[0035] Comparative Example 1-1 The only difference from Example 2 was that the chemical composition of the substrate was Ag-5wt.%Cu-1wt.%Ni, and the total amount of impurity elements in the electrical contact material was 0.08wt.%.

[0036] The AgCuNi-based electrical contact material of this comparative example had the following properties: the density was 97%, the hardness was 142 Hv, the tensile strength was 450 MPa, the salt spray resistance time was 80 h, and there was too much Cu-rich phase, which weakened the solid solution improvement effect and affected the performance.

[0037] Comparative Example 1-2 The only difference from Example 2 was that Bi-Sn alloy was not added, and the total amount of impurity elements in the electrical contact material was 0.08wt.%.

[0038] The AgCuNi-based electrical contact material of this comparative example had the following properties: the density was 95%, the hardness was 133 Hv, the tensile strength was 424 MPa, and the salt spray resistance time was 78 h, and the density was not enough, which affected the performance.

[0039] Comparative Example 1-3 The only difference from Example 2 was that Sn element was added, and the total amount of impurity elements in the electrical contact material was 0.08wt.%.

[0040] The AgCuNi-based electrical contact material of this comparative example had the following properties: the density was 95%, the hardness was 136 Hv, the tensile strength was 434 MPa, and the salt spray resistance time was 79 h, and the density was not enough, which affected the performance.

[0041] Comparative Example 1-4 The only difference from Example 2 is that the Bi-Sn alloy is added in an amount of 5%, and the total amount of impurity elements of the electrical contact material is 0.08wt.%. The performance of the AgCuNi-based electrical contact material of the present comparative example is: the density is 93%, the hardness is 126 Hv, the tensile strength is 414 MPa, and the salt spray resistance time is 80 h. The density is not enough, which affects the performance.

[0042] Comparative Example 1-5 The only difference from Example 2 is that the Bi-20wt.% Sn alloy is added, and the total amount of impurity elements of the electrical contact material is 0.08wt.%. The performance of the AgCuNi-based electrical contact material of the present comparative example is: the density is 94%, the hardness is 133 Hv, the tensile strength is 421 MPa, and the salt spray resistance time is 80 h. The thermal stress is large, which affects the performance.

[0043] Comparative Example 2 The only difference from Example 2 is that vacuum sintering is used; the total amount of impurity elements of the electrical contact material is 0.2wt.%, the density is 96%, the hardness is 130 Hv, the tensile strength is 412 MPa, and the salt spray resistance time is 75 h. The impurity content is high, which affects the performance.

[0044] Comparative Example 3 The only difference from Example 2 is that no solid solution treatment is performed, the total amount of impurity elements of the electrical contact material is 0.08wt.%, the density is 98%, the hardness is 142 Hv, the tensile strength is 460 MPa, and the salt spray resistance time is 70 h. The second phase is high, which affects the performance.

[0045] Comparative Example 3-1 The only difference from Example 2 is that the solid solution temperature is 600°C, the total amount of impurity elements of the electrical contact material is 0.08wt.%, the density is 98%, the hardness is 143 Hv, the strength is 470 MPa, and the salt spray resistance time is 86 h. The grain grows, which affects the performance.

[0046] Comparative Example 3-2 The only difference from Example 2 is that the holding time is 0.5 h, the total amount of impurity elements of the electrical contact material is 0.08wt.%, the density is 98%, the hardness is 141 Hv, the strength is 466 MPa, and the salt spray resistance time is 72 h. The second phase is still left, which affects the performance.

[0047] The foregoing description of specific exemplary embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the application be limited not with this detailed description, but rather by the claims appended hereto.

Claims

1. A method for producing an AgCuNi-based electric contact material, characterized by, The method comprises the following steps: (1) mixing powder A and powder B to obtain AgCuNi-based alloy powder; the chemical composition of the powder A is Ag-xCu-yNi, x is 0.5-3 wt.%, y is 1-2 wt.%; the chemical composition of the powder B is Bi-zSn, z is 40-60 wt.%, the mass percentage of the powder B in the AgCuNi-based alloy powder is 10-15%; (2) mixing and granulating the AgCuNi-based alloy powder obtained in step (1) with a binder to obtain a feedstock; (3) injection molding the feedstock to obtain a green body, and degreasing the green body to obtain a degreased body; (4) sequentially sintering and densifying the degreased body to obtain a sintered body, and subjecting the sintered body to solid solution treatment to obtain an AgCuNi-based electrical contact material; the sintering and densifying process is as follows: placing the degreased body in a hydrogen sintering furnace, vacuumizing, then passing hydrogen, and heating at a heating rate of 2-5 ℃ / min to 700-900 ℃, keeping the temperature for 1-2 h, and cooling to room temperature in the furnace and discharging.

2. The method of producing an AgCuNi-based electric contact material according to claim 1, characterized by, the solid solution treatment process is as follows: placing the sintered body in an argon atmosphere protection, heating at a heating rate of 2-5 ℃ / min to 400-500 ℃, keeping the temperature for 1-2 h, and then cooling to room temperature in a quenching oil.

3. The method of producing an AgCuNi-based electric contact material according to claim 1, characterized by, the average particle size of the powder A is 1-3 μm, and the average particle size of the powder B is 0.2-0.5 μm, both of which are prepared by gas atomization or water-gas combined atomization.

4. The method of producing an AgCuNi-based electric contact material according to claim 1, characterized by, in step (2), the binder is composed of the following components in mass percentage: polyformaldehyde 60-75%, high-density polyethylene 10-15%, polypropylene 10-15%, ethylene-propylene copolymer rubber 3-5%, and stearic acid 2-5%; the mass ratio of the binder to the AgCuNi-based alloy powder is 7.1-8.6%:91.4-92.9%.

5. The method of producing an AgCuNi-based electric contact material according to claim 1, characterized by, the mixing process parameters are as follows: the mixing temperature is 160-200 ℃, and the mixing time is 1-2 h.

6. The method of producing an AgCuNi-based electric contact material according to claim 1, characterized by, the injection process parameters are as follows: the injection temperature is 160-190 ℃, the injection pressure is 80-160 MPa, and the mold temperature is 30-60 ℃.

7. The method of producing an AgCuNi-based electric contact material according to claim 1, characterized by, in step (3), the degreasing process comprises two steps of catalytic degreasing and thermal degreasing; the catalytic degreasing process parameters are as follows: the flow rate of nitric acid is 1-4 ml / min, the catalytic degreasing temperature is 120-140 ℃, and the catalytic degreasing time is 10-16 h; the thermal degreasing process is as follows: in a vacuum degreasing furnace, heating to 400-500 ℃ at a rate of 2-5 ℃ / min under argon atmosphere protection, keeping the temperature for 2-4 h, and then cooling to room temperature in the furnace.

8. The method of producing an AgCuNi-based electric contact material according to claim 1, characterized by, the AgCuNi-based electrical contact material contains inevitable impurity elements, and the impurity elements are required to have the following mass percentages: the content of C is ≤0.02 wt.%, the content of O is ≤0.02 wt.%, the content of P is ≤0.02 wt.%, the content of S is ≤0.02 wt.%, and the total content of the impurity elements is ≤0.08 wt.%.

9. An AgCuNi-based electrical contact material, characterized in that, the electrical contact material is prepared by the preparation method in any one of claims 1-8.

10. The AgCuNi-based electrical contact material of claim 9, wherein, The relative density of the electrical contact material is ≥ 99%, the hardness of the electrical contact material is ≥ 155 Hv, the strength of the electrical contact material is ≥ 500 MPa, and the salt spray resistance time is ≥ 96 h.

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