Silver tin oxide indium oxide electrical contact material applied to automobile relay and preparation method of silver tin oxide indium oxide electrical contact material

Abstract

The invention discloses a silver tin oxide indium oxide electrical contact material applied to an automobile relay and a preparation method of the silver tin oxide indium oxide electrical contact material. The preparation method comprises the following steps: S1, performing plasma treatment on In2O3 by using mixed gas of inert gas and reducing gas; s2, Ag powder, SnO2 fibers and In2O3 powder are mixed to obtain mixed powder, the content of the SnO2 fibers in the mixed powder is 6-10 wt%, and the content of In2O3 in the mixed powder is 4-8 wt%; the SnO2 fiber is prepared by the following steps: dissolving 20-60 parts by weight of SnCl4. 5H2O and 3-5 parts by weight of SbCl3 into N, N-dimethylformamide, adding polyvinylpyrrolidone, stirring, standing to obtain a mixed solution, carrying out electrostatic spinning on the mixed solution to obtain a fiber precursor, and calcining the fiber precursor to obtain the SnO2 fiber. The SnO2 fiber is prepared from 20-60 parts by weight of SnCl4. 5H2O and 3-5 parts by weight of SbCl3. The electrical contact material prepared by the method has wide field adaptability and is suitable for working scenes of automobile relays.

Description

TECHNICAL FIELD

[0001] The application relates to the field of electrical materials, in particular to a silver tin oxide indium oxide electrical contact material applied to an automobile relay and a preparation method thereof. BACKGROUND

[0002] As an environmentally friendly low-voltage contact material, the silver tin oxide electrical contact material has gradually replaced the toxic silver cadmium oxide and is widely applied to the fields of contactors, general relays and automobile relays. The core advantage lies in the high melting point characteristic of SnO2 particles, which can form a dense protective layer and significantly improve the resistance to welding and the resistance to arc erosion. The current mainstream process includes alloy internal oxidation and powder metallurgy. By optimizing the SnO2 content and adding In2O3 and other modifying elements, the resistance to material transfer under direct current load is further improved, and the dual requirements of environmental protection and reliability for automobile electronics are met.

[0003] However, the existing silver tin oxide electrical contact material still has the defect of wide-temperature-range adaptability. In the application of automobile relays, under low-temperature environment, the interface bonding strength of the hard and brittle phase of SnO2 and the silver matrix is significantly reduced, which causes the peeling of the oxidation layer on the contact surface, causes the unstable contact resistance, and especially in the frequent on-off scene, micro-motion wear is prone to occur. Under high-temperature environment, the difference between the thermal expansion coefficients of SnO2 and silver causes the interface stress concentration, accelerates the cracking of the oxidation layer, and the softening of the silver matrix causes the contact deformation, and the temperature rise exceeds the standard. SUMMARY

[0004] In order to improve the problem of insufficient wide-temperature-range adaptability of the electrical contact material, a silver tin oxide indium oxide electrical contact material applied to an automobile relay and a preparation method thereof are provided.

[0005] The above application purpose of the application is realized by the following technical scheme: A preparation method of a silver tin oxide indium oxide electrical contact material applied to an automobile relay, comprising the following steps: S1: treating In2O3 by using a mixed gas plasma of inert gas and reducing gas; S2: mixing Ag powder, SnO2 fiber and In2O3 powder to obtain a mixed powder, wherein the content of SnO2 fiber in the mixed powder is 6-10 wt%, and the content of In2O3 is 4-8 wt%; The SnO2 fiber is prepared by the following method: SnCl4.5H2O and SbCl3 are dissolved into N,N-dimethylformamide, polyvinylpyrrolidone is added and stirred, then the mixture is left to obtain a mixed solution, the mixed solution is electrospun to obtain a fiber raw yarn, and the fiber raw yarn is calcined to obtain SnO2 fiber, wherein the amount of SnCl4.5H2O is 20-60 parts by weight, and the amount of SbCl3 is 3-5 parts by weight.

[0006] By adopting the technical scheme, the electrospinning technology can produce nanofibers with uniform diameter and high length-diameter ratio, the fiber structure forms a three-dimensional network reinforcing phase in the silver matrix, the fibrous tin oxide has higher structural stability than the granular tin oxide, can effectively inhibit the grain boundary sliding of the silver matrix during thermal cycling, reduce thermal stress concentration, and make the material not easy to be brittle at low temperature; when the trivalent Sb is doped into the SnO2 lattice, point defects and free carriers are generated due to the difference in valence, and the oxygen vacancy concentration remains stable in a wide temperature range, so that the electrical contact material maintains a low resistivity; the high-activity particles generated by the plasma treatment can partially reduce the surface of In2O3 to generate oxygen vacancies, improve the wettability of In2O3 and the silver matrix, and improve the interface bonding energy to inhibit the surface diffusion and oxidation of silver atoms at high temperature, and improve the low-temperature toughness.

[0007] Optionally, the mixed powder in S2 further includes 0.1-0.9wt% CeO2 powder.

[0008] By adopting the technical scheme, the four-valent Ce in CeO2 can effectively capture the dissolved oxygen in the silver matrix at high temperature, prevent the diffusion of oxygen into the material, and inhibit the grain growth of SnO2 at high temperature, so that the electrical contact material is not easy to be oxidized at high temperature.

[0009] Optionally, the mixed powder in S2 further includes 0.05-0.2wt% graphene powder.

[0010] By adopting the technical scheme, graphene has high thermal conductivity and can quickly diffuse the heat generated by the arc at high temperature, graphene has strong bonding energy with silver, and can absorb impact energy through the flexible deformation of graphene at low temperature to prevent brittle crack propagation.

[0011] Optionally, the reducing gas in S1 is H2.

[0012] By adopting the technical scheme, H2 has strong reducing property, in the plasma environment, H2 molecules are ionized into excited-state hydrogen atoms, and these high-activity hydrogen atoms will react with the oxygen on the surface of In2O3 to partially reduce In2O3 to generate In element or low-valence indium oxide, which can improve the chemical properties of the surface of In2O3, increase the surface active sites, and improve the interface bonding ability of In2O3 and other powders, so that the mixed powder is more uniform and stable.

[0013] Optionally, 3-5 parts of polyethylene glycol are added before the polyvinylpyrrolidone is added in the SnO2 fiber preparation method.

[0014] By employing the above technical solution, the -O- bonds in the polyethylene glycol molecular chain can form hydrogen bonds with the Sn-OH groups generated by the hydrolysis of SnCl4·5H2O, thereby regulating the rheological properties of the precursor solution, increasing the solution viscosity, and obtaining tin oxide fibers with uniform diameter. Furthermore, polyethylene glycol forms a complex with SbCl3, delaying the degradation of Sb. 3+ The hydrolysis rate of Sb 3+ More uniform doping of SnO2 lattice.

[0015] Optionally, 0.5 to 2 parts of citric acid are added before adding polyvinylpyrrolidone in the SnO2 fiber preparation method.

[0016] By adopting the above technical solution, citric acid is adsorbed on SnO2 on the (110) plane, which inhibits crystal growth in this direction and promotes the preferential growth of fibers along the

[001] direction, so that the fibers have higher axial thermal conductivity, which is conducive to the rapid diffusion of axial heat at high temperature and reduces thermal resistance.

[0017] Optionally, in the SnO2 fiber preparation method, the mass ratio of SnCl4·5H2O to SbCl3 is (8-12):1.

[0018] By adopting the above technical solution, the phase transformation activation energy of SnO2 can be improved when the mass ratio is in the range of (8~12):1, the transformation from tetragonal phase to orthorhombic phase at high temperature can be suppressed, the phase transformation temperature of SnO2 can be increased, and the high-temperature lattice stability of the material can be improved.

[0019] The second objective of this invention is achieved through the following technical solution: A silver oxide-indium oxide electrical contact material for automotive relays, obtained by any of the above preparation methods.

[0020] By adopting the above technical solution, the electrical contact material has good flexibility and conductivity in low-temperature environments and is not easily brittle; in high-temperature environments, it has excellent oxidation resistance and heat dissipation performance, with a small deviation in the coefficient of thermal expansion. It can work stably in the wide temperature range environment where automotive relays are located, ensuring the reliability and stability of automotive relays and improving the adaptability of electrical contacts in a wide temperature range.

[0021] In summary, this application has at least the following beneficial effects: (1) The fibrous tin oxide structure is more stable, which can effectively suppress the grain boundary slip of the matrix silver, reduce thermal stress concentration, and make the material less brittle at low temperature. (2) Trivalent Sb doping into SnO2 lattice generates point defects and free carriers. The oxygen vacancy concentration remains basically stable over a wide temperature range, resulting in low resistivity of the electrical contact material. (3) The high activity particles generated by plasma treatment can partially reduce the surface of In2O3, generate oxygen vacancies, enhance wettability, inhibit the surface diffusion and oxidation of silver atoms at high temperature, and improve low-temperature toughness. DETAILED DESCRIPTION

[0022] Raw materials SnCl4·5H2O, purity ≥ 99.995wt%, purchased from Shanghai Kanglang Biotechnology Co., Ltd.; SbCl3, purity ≥ 99wt%, purchased from Shanghai Maikelin Technology Co., Ltd.; Polyethylene glycol, average molecular weight 4000, purchased from Shanghai Yuanye Biotechnology Co., Ltd.; N,N-dimethylformamide, purity ≥ 99.5wt%, purchased from Shanghai Maikelin Technology Co., Ltd.; Polyvinylpyrrolidone, average molecular weight 2500, purchased from Shanghai Maikelin Technology Co., Ltd.; Graphene powder, brand JCHQGP, purity > 98wt%, thickness 0.55-3.74nm, layer number 2, particle size < 10μm, specific surface area 420-550m 2 / g, purchased from Chengdu Jiacai Technology Co., Ltd.; Citric acid, analytical grade, from market; Ag powder, In2O3 powder, CeO2 powder are all from market, among which the average particle size of Ag powder is 5μm, purity 99.999wt%, the average particle size of In2O3 powder is 60nm, purity 99.99wt%, the average particle size of CeO2 powder is 200nm, purity 99.99wt%, and the average particle size of SnO2 powder is 70nm, purity 99.99wt%.

[0023] Preparation Example 1 A SnO2 fiber is prepared as follows: 4g SnCl4·5H2O, 0.4g SbCl3, 0.4g polyethylene glycol and 0.1g citric acid are added into 50mL N,N-dimethylformamide, stirred at 50℃ water bath at 300rpm for 2h to completely dissolve, 4g polyvinylpyrrolidone is added, stirred at 60rpm for 4h, and then left to stand at 25℃ for 24h to obtain a mixed solution, the mixed solution is electrospun to obtain fiber filaments, wherein the electrospinning process parameters are: positive voltage 16kv, negative voltage 4kv, injection pump flow rate 1mL / h, and receiving distance 14cm, the fiber is added into a reaction furnace, heated from room temperature (25℃) to 300℃ at a speed of 5℃ / min, kept for two hours, and then naturally cooled to 25℃ to obtain SnO2 fiber.

[0024] Preparation Example 2 A SnO2 fiber, which is different from Preparation Example 1 in that SbCl3 is not added to the mixed solution; the rest is the same as Preparation Example 1.

[0025] Preparation Example 3 A SnO2 fiber, which is different from Preparation Example 1 in that polyethylene glycol is not added to the mixed solution; the rest is the same as Preparation Example 1.

[0026] Preparation Example 4 A SnO2 fiber, which is different from Preparation Example 1 in that citric acid is not added to the mixed solution; the rest is the same as Preparation Example 1.

[0027] Preparation Example 5 A SnO2 fiber, which is different from Preparation Example 1 in that SnCl4·5H2O in the mixed solution is 3.2 g; the rest is the same as Preparation Example 1.

[0028] Preparation Example 6 A SnO2 fiber, which is different from Preparation Example 1 in that SnCl4·5H2O in the mixed solution is 4.8 g; the rest is the same as Preparation Example 1.

[0029] Preparation Example 7 A SnO2 fiber, which is different from Preparation Example 1 in that SnCl4·5H2O in the mixed solution is 2.8 g; the rest is the same as Preparation Example 1.

[0030] Preparation Example 8 A SnO2 fiber, which is different from Preparation Example 1 in that SnCl4·5H2O in the mixed solution is 5.2 g; the rest is the same as Preparation Example 1.

[0031] Preparation Example 9 A SnO2 fiber, which is different from Preparation Example 1 in that SnCl4·5H2O in the mixed solution is 2 g, SbCl3 is 0.3 g, polyethylene glycol is 0.3 g, and citric acid is 0.05 g; the rest is the same as Preparation Example 1.

[0032] Preparation Example 10 A SnO2 fiber, which is different from Preparation Example 1 in that SnCl4·5H2O in the mixed solution is 6 g, SbCl3 is 0.5 g, polyethylene glycol is 0.5 g, and citric acid is 0.2 g; the rest is the same as Preparation Example 1.

[0033] Example 1 A silver tin oxide indium oxide electrical contact material applied to an automobile relay, the preparation method is as follows: S1: 60 g of In2O3 powder was vacuum dried at 120 °C for 4 h, vacuum degree ≤-0.09 MPa, and the vacuum dried In2O3 was added to the reaction chamber of the plasma machine. A mixed gas of Ar and H2 was introduced into the reaction chamber of the plasma machine, the volume ratio of Ar and H2 was 9:1, the partial pressure of H2 was 2 kPa, and the plasma treatment was carried out for 3 min by applying a radio frequency power of 14 MHz and 150 W to obtain plasma treated In2O3 powder; S2: 854 g of Ag powder, 80 g of SnO2 fiber, 60 g of plasma treated In2O3 powder, 5 g of CeO2 powder and 1 g of graphene powder were added to a powder mixer and mixed at a speed of 30 rpm for 8 h, and the direction was reversed every 2 h to obtain a mixed powder, wherein the SnO2 fiber was obtained from Preparation Example 1; S3: The mixed powder was cold pressed into a Φ10 mm x 5 mm cylindrical blank at 500 MPa, and the pressure was maintained for 30 s, then the cylinder was placed in a vacuum hot pressing furnace and hot pressed at 600 °C and 30 MPa in a H2 atmosphere for 2 h to obtain a sintered blank, the sintered blank was preheated at 900 °C for 1 h, the mold was preheated to 500 °C, and a rod with a diameter of 10 mm was extruded, wherein the extrusion ratio was 10:1 and the extrusion speed was 2 cm / min. The rod was cold drawn into a wire contact material with a diameter of 2 mm.

[0034] Comparative Example 1 A silver tin oxide indium contact material for automobile relays, which is different from Example 1 in that the SnO2 fiber in S2 is obtained from Preparation Example 2; the rest is the same as Example 1.

[0035] Comparative Example 2 A silver tin oxide indium contact material for automobile relays, which is different from Example 1 in that the In2O3 is not subjected to the plasma treatment in S1, only vacuum dried at 120 °C for 4 h, and the vacuum dried In2O3 is added to the mixed powder in S2; the rest is the same as Example 1.

[0036] Example 2 A silver tin oxide indium contact material for automobile relays, which is different from Example 1 in that no CeO2 powder is added in S2, and the Ag powder is 859 g; the rest is the same as Example 1.

[0037] Example 3 A silver tin oxide indium contact material for automobile relays, which is different from Example 1 in that no graphene powder is added in S2, and the Ag powder is 855 g; the rest is the same as Example 1.

[0038] Example 4 A silver-tin oxide-indium oxide electrical contact material applied to an automobile relay, which is different from example 1 in that: in step S1, mixed gas of Ar and NH3 is passed into the reaction cavity of the plasma machine, the volume ratio of Ar and NH3 is 9:1, and the partial pressure of NH3 is 2 kPa; the rest is the same as example 1.

[0039] Example 5 A silver-tin oxide-indium oxide electrical contact material applied to an automobile relay, which is different from example 1 in that: in step S2, the SnO2 fiber comes from preparation example 3; the rest is the same as example 1.

[0040] Example 6 A silver-tin oxide-indium oxide electrical contact material applied to an automobile relay, which is different from example 1 in that: in step S2, the SnO2 fiber comes from preparation example 4; the rest is the same as example 1.

[0041] Example 7 A silver-tin oxide-indium oxide electrical contact material applied to an automobile relay, which is different from example 1 in that: in step S2, the SnO2 fiber comes from preparation example 5; the rest is the same as example 1.

[0042] Example 8 A silver-tin oxide-indium oxide electrical contact material applied to an automobile relay, which is different from example 1 in that: in step S2, the SnO2 fiber comes from preparation example 6; the rest is the same as example 1.

[0043] Example 9 A silver-tin oxide-indium oxide electrical contact material applied to an automobile relay, which is different from example 1 in that: in step S2, the SnO2 fiber comes from preparation example 7; the rest is the same as example 1.

[0044] Example 10 A silver-tin oxide-indium oxide electrical contact material applied to an automobile relay, which is different from example 1 in that: in step S2, the SnO2 fiber comes from preparation example 8; the rest is the same as example 1.

[0045] Example 11 A silver-tin oxide-indium oxide electrical contact material applied to an automobile relay, which is different from example 1 in that: in step S2, the Ag powder is 898.5 g, the SnO2 fiber is 60 g, the In2O3 powder is 40 g, the CeO2 powder is 1 g, and the graphene powder is 0.5 g, and the SnO2 fiber comes from preparation example 7; the rest is the same as example 1.

[0046] Example 12 A silver tin oxide indium oxide electrical contact material applied to an automobile relay, which is different from example 1 in that: in step S2, the Ag powder is 809 g, the SnO2 fiber is 100 g, the In2O3 powder is subjected to plasma treatment, the CeO2 powder is 9 g, and the graphene powder is 2 g, and the SnO2 fiber is derived from preparation example 7; the rest is the same as example 1.

[0047] According to GB / T 5586-2016 "Test method for basic properties of electrical contact material", the tensile strength of the electrical contact materials of examples 1-12 and comparative examples 1-2 was measured after being kept at-40℃ for 5h and then heated to 25℃, the sample was a wire with an original gauge length of 100mm and a diameter of 2mm, the test temperature was 25℃, and the detection results are shown in Table 1; according to GB / T 15078-2021 "Test method for contact resistance of noble metal electrical contact material", the volume resistance of the electrical contact materials of examples 1-12 and comparative examples 1-2 was measured after being heated to 150℃ for 1h and then naturally cooled to 25℃, the sample was a wire with an original gauge length of 100mm and a diameter of 2mm, the test temperature was 25℃, and the measurement was carried out under direct current conditions, the current was 50mA, the open circuit voltage was 1V, and the static contact pressure was 100cN, and the measurement results are shown in Table 1.

[0048] Table 1 Performance detection results of electrical contact materials of examples and comparative examples Tensile strength (MPa) Volume resistance (μΩ-cm) Example 1 365 12.5 Example 2 342 13.8 Example 3 338 13.2 Example 4 355 13.5 Example 5 363 13.2 Example 6 364 13.0 Example 7 352 12.8 Example 8 359 12.7 Example 9 351 13.1 Example 10 354 13.0 Example 11 361 13.1 Example 12 358 13.4 Comparative Example 1 361 15.0 Comparative Example 2 295 13.9 In combination with Table 1, the examples 1-12, comparative examples 1-2 and detection results are analyzed as follows: Comparing comparative example 1 and comparative example 2, the tensile strength of the electrical contact material of example 1 is greater than that of the electrical contact material of comparative example 2, and the volume resistance of the electrical contact material of example 1 is less than that of the electrical contact material of comparative example 2.

[0049] The difference between example 1 and comparative example 1 is that: in step S2 of the preparation method of example 1, SnO2 fiber is doped with antimony; when trivalent Sb is incorporated into the SnO2 lattice, it will replace the position of tetravalent Sn, and due to the difference in valence, point defects and free carriers are generated, and the oxygen vacancy concentration remains stable, and the electrical contact material has low resistivity; therefore, it is necessary to dope SnO2 fiber with antimony. Comparing comparative example 1 and comparative example 2, the tensile strength of the electrical contact material of example 1 is greater than that of the electrical contact material of comparative example 2, and the volume resistance of the electrical contact material of example 1 is less than that of the electrical contact material of comparative example 2.

[0050] The difference between example 1 and comparative example 2 is that: in step S2 of the preparation method of example 1, In2O3 is subjected to plasma treatment; plasma treatment can produce oxygen vacancies on the surface of In2O3, inhibit the surface diffusion and oxidation of silver atoms at high temperature, and improve the low temperature toughness; therefore, it is necessary to subject In2O3 to plasma treatment.

[0051] Comparing comparative example 1 and example 2, the tensile strength of the electrical contact material of example 1 is greater than that of example 2, and the volume resistance of the electrical contact material of example 1 is smaller than that of example 2.

[0052] The difference between example 1 and example 2 is that CeO2 is added in S2 step of example 1; the tetravalent Ce in CeO2 can effectively capture the dissolved oxygen in the silver matrix, inhibit the grain growth of SnO2, and make the electrical contact material not easy to be oxidized at high temperature; therefore, it is known that adding CeO2 in S2 step is better.

[0053] Comparing comparative example 1 and example 3, the tensile strength of the electrical contact material of example 1 is smaller than that of example 3, and the volume resistance of the electrical contact material of example 1 is smaller than that of example 3.

[0054] The difference between example 1 and example 3 is that graphene is added in S2 step of example 1; graphene has high thermal conductivity, can quickly spread heat at high temperature, and has strong binding energy with silver, which prevents the brittle crack propagation of the electrical contact material at low temperature; therefore, it is known that adding graphene in S2 step is better.

[0055] Comparing comparative example 1 and example 4, the tensile strength of the electrical contact material of example 1 is smaller than that of example 4, and the volume resistance of the electrical contact material of example 1 is smaller than that of example 4.

[0056] The difference between example 1 and example 4 is that H2 is used as the reducing gas in the plasma machine reaction cavity in S1 step of example 1; H2 is ionized into excited state hydrogen atoms, and the high activity hydrogen atoms partially reduce In2O3, improve the chemical properties of the In2O3 surface, increase the surface active sites, improve the interface bonding ability of In2O3 and other powders, and make the mixed powders more uniform and stable; therefore, it is known that using H2 as the reducing gas in the plasma machine reaction in S1 step is better.

[0057] Comparing comparative example 1 and example 5, the tensile strength of the electrical contact material of example 1 is close to that of example 5, and the volume resistance of the electrical contact material of example 1 is smaller than that of example 5.

[0058] The difference between example 1 and example 5 is that polyethylene glycol is added when SnO2 fibers are prepared in S2 step of example 1; polyethylene glycol forms a complex with SbCl3, delays the hydrolysis rate of Sb 3+ , and makes the trivalent Sb more uniformly doped into the SnO2 lattice; therefore, it is known that adding polyethylene glycol when SnO2 fibers are prepared in S2 is better.

[0059] Comparative Example 1 and Example 6, the tensile strength of the electrical contact material of Example 1 is close to that of the electrical contact material of Example 6, and the volume resistance of the electrical contact material of Example 1 is less than that of the electrical contact material of Example 6.

[0060] The difference between Example 1 and Example 6 is that citric acid is added during the preparation of SnO2 fibers in S2 step in Example 1; citric acid promotes the preferred growth of fibers, so that the fibers have higher axial thermal conductivity, which is beneficial to the rapid diffusion of axial heat at high temperature and reduces the thermal resistance; therefore, it is known that it is better to add citric acid during the preparation of SnO2 fibers in S2.

[0061] Comparative Example 1 and Examples 7-10, the tensile strength of the electrical contact material of Example 1 is less than that of the electrical contact materials of Examples 7-10, and the volume resistance of the electrical contact material of Example 1 is less than that of the electrical contact materials of Examples 7-10; the tensile strength of the electrical contact materials of Examples 7-8 is less than that of the electrical contact materials of Examples 9-10, and the volume resistance of the electrical contact materials of Examples 7-8 is less than that of the electrical contact materials of Examples 9-10.

[0062] The difference between Example 1, Examples 7-8 and Examples 9-10 is that the mass ratio of SnCl4·5H2O to SbCl3 during the preparation of SnO2 fibers in S2 step of the preparation method of Example 1 and Examples 7-8 is within the range of (8-12):1, and the mass ratio of SnCl4·5H2O to SbCl3 during the preparation of SnO2 fibers in Example 1 is 10:1; within the range of (8-12):1, the phase transition from tetragonal phase to orthorhombic phase at high temperature is inhibited, the phase transition temperature of SnO2 is improved, and the lattice stability of the material at high working temperature is improved; therefore, it is known that the mass ratio of SnCl4·5H2O to SbCl3 during the preparation of SnO2 fibers in S2 is within the range of (8-12):1 is better, and the mass ratio of SnCl4·5H2O to SbCl3 during the preparation of SnO2 fibers is 10:1 within the range of (8-12):1 is better.

[0063] Comparative Example 1 and Examples 11-12, the tensile strength of the electrical contact material of Example 1 is less than that of the electrical contact materials of Examples 11-12, and the volume resistance of the electrical contact material of Example 1 is less than that of the electrical contact materials of Examples 11-12.

[0064] The difference between Example 1 and Examples 11-12 is that the mass ratio of Ag, SnO2, In2O3, CeO2, graphene in the step S2 of the electrical contact material S2 of Example 1 is 854:80:60:5, wherein the mass ratio of SnCl4·5H2O, SbCl3, polyethylene glycol, citric acid in the preparation of SnO2 fiber is 40:4:4:1; it can be known that the mass ratio of Ag, SnO2, In2O3, CeO2, graphene in the step S2 of the electrical contact material S2 is 854:80:60:5 and the mass ratio of SnCl4·5H2O, SbCl3, polyethylene glycol, citric acid in the preparation of SnO2 fiber is 40:4:4:1 is relatively optimal.

[0065] The specific embodiments are only an explanation of the present application, which is not a limitation of the present application, and those skilled in the art can make modifications to the embodiments without creative contribution according to the needs after reading the specification, but as long as it is within the scope of the present application, it is protected by the patent law.

Claims

1. A method for preparing silver-tin-indium oxide electrical contact material for automotive relays, characterized in that, Includes the following steps: S1: In2O3 is treated with a mixed gas plasma of inert and reducing gases; S2: Ag powder, SnO2 fiber and In2O3 powder are mixed to obtain a mixed powder, wherein the content of SnO2 fiber in the mixed powder is 6~10wt% and the content of In2O3 is 4~8wt%; The SnO2 fiber is prepared by the following method: SnCl4·5H2O and SbCl3 are dissolved in N,N-dimethylformamide, polyvinylpyrrolidone is added and stirred, and then allowed to stand to obtain a mixture. The mixture is electrospun to obtain fiber precursor, and the fiber precursor is calcined to obtain SnO2 fiber, wherein SnCl4·5H2O is 20~60 parts by weight and SbCl3 is 3~5 parts by weight.

2. The method for preparing a silver oxide-indium oxide electrical contact material for automotive relays according to claim 1, characterized in that, The powder mixture in step S2 also includes 0.1~0.9wt% CeO2 powder.

3. The method for preparing a silver oxide-indium oxide electrical contact material for automotive relays according to claim 1, characterized in that, The powder mixture in step S2 also includes 0.05~0.2wt% graphene powder.

4. The method for preparing a silver oxide-indium oxide electrical contact material for automotive relays according to claim 1, characterized in that, The reducing gas in step S1 is H2.

5. The method for preparing a silver oxide-indium oxide electrical contact material for automotive relays according to claim 1, characterized in that, In the SnO2 fiber preparation method, 3-5 parts of polyethylene glycol are added before adding polyvinylpyrrolidone.

6. The method for preparing a silver-tin-indium oxide electrical contact material for automotive relays according to claim 1, characterized in that, In the SnO2 fiber preparation method, 0.5 to 2 parts of citric acid are added before adding polyvinylpyrrolidone.

7. The method for preparing a silver-tin-indium oxide electrical contact material for automotive relays according to claim 6, characterized in that, In the SnO2 fiber preparation method, the mass ratio of SnCl4·5H2O to SbCl3 is (8~12):

1.

8. A silver-tin-indium oxide electrical contact material for automotive relays, obtained by the preparation method according to any one of claims 1 to 7.