Silver-based composite material preparation method based on in-situ disproportionation reaction interface regulation and control

Abstract

The invention discloses a silver-based composite material preparation method based on in-situ disproportionation reaction interface regulation and control. According to the method, a new silver salt-low-valence metal oxide composite precursor system is constructed, and coated Ag-MeO composite powder is prepared through thermal decomposition of molten salt; secondly, in-situ disproportionation reaction of low-valence metal oxide in the silver matrix is achieved through the hot pressing sintering process, generated metal simple substances and Ag form an alloy interface, and therefore the silver-based composite ingot with strong interface combination and excellent tensile strength and ductility is obtained; and the hot extrusion technology and the dip angle rolling technology are combined, and the orientation distribution of oxide particles in a silver matrix is controllable by regulating and controlling technological parameters of hot extrusion and multi-pass dip angle rolling, so that the high-toughness and high-corrosion-resistance silver-based composite contact material is obtained. The method is simple in technological process, environmentally friendly and low in cost, and has great industrial production potential.

Description

Technical Field

[0001] The invention relates to an interface control technology for a silver-based composite material, and in particular to a method for preparing a silver-based composite material based on in-situ disproportionation reaction interface control. Background Art

[0002] Electrical contact materials are key strategic materials to ensure safe and reliable operation of new energy fields such as photovoltaics, wind power, electric vehicles, and DC charging piles. They are responsible for connecting and disconnecting circuits and load currents. Their performance directly determines the breaking capacity and reliability of control electrical appliances. Among electrical contact materials, silver-based metal oxide composite materials (Ag / MeO) have been widely used because of their good resistance to welding, electrical conductivity, and low contact resistance. However, the weak interface bonding between metal oxides and the silver matrix causes the metal oxides to segregate to the surface of the material during service, greatly deteriorating the arc erosion resistance. Therefore, researchers have conducted a lot of research on improving the interface bonding between metal oxides and the silver matrix.

[0003] At present, researchers mainly use the methods of introducing additives and surface coating modification to improve the interface bonding strength. For example, no SnO2-rich layer is found in the remelting area of ​​the Ag / SnO2 material with CuO added, and the SnO2 particles are still retained in the silver matrix, which enhances the wettability of SnO2 in the Ag molten pool and inhibits the segregation of SnO2 particles on the surface. However, the amount of CuO needs to be precisely controlled, and the method of improving the interface bonding is non-reactive wetting, which has no obvious effect on enhancing the arc erosion resistance. Researchers use chemical plating to deposit Ag on the surface of titanium-doped SnO2 particles, achieve uniform distribution of Ag-deposited SnO2 particles in the silver matrix, improve the interface bonding strength between Ag and SnO2, and improve the conductivity, hardness and thermal stability of Ag / SnO2 materials. However, the chemical plating method has high cost, complex procedures, and difficulty in accurately controlling the thickness of the interface coating, which limits its further promotion and application. Therefore, seeking more efficient and simple improvement strategies to enhance the Ag / MeO interface bonding and synergistically enhance the mechanical and arc erosion resistance of Ag / MeO materials has become a challenging but necessary effort. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a silver-based composite material based on in-situ disproportionation reaction interface regulation. The method uses low-valent metal oxide as the second phase, utilizes thermal decomposition of molten silver salt to form a coated composite oxide powder, and the low-valent metal oxide undergoes a disproportionation reaction under a vacuum hot pressing process to generate a metal element, and the metal element diffuses with Ag at a certain pressure and temperature to form an alloy layer, which significantly improves the interface bonding strength and enhances the mechanical and arc erosion resistance of the Ag / MeO material.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for preparing a silver-based composite material based on in-situ disproportionation reaction interface regulation, the method comprising: first, constructing a new "silver salt-low-valent metal oxide" composite precursor system, and using a molten salt thermal decomposition method to obtain a coated composite oxide powder. Then, through a hot pressing sintering process, an in-situ disproportionation reaction of low-valent metal oxides in a silver matrix is ​​achieved, and the generated metal element diffuses with Ag at a certain pressure and temperature to form an alloy layer, which significantly improves the interface bonding strength; combined with hot extrusion and multi-pass angle rolling, the orientation distribution of oxide particles in the silver matrix is ​​controllable, and smooth extrusion can be achieved at a lower extrusion temperature, greatly improving the performance of silver-based composite materials such as electrical contact materials.

[0007] Specifically, the method for preparing a silver-based composite material based on in-situ disproportionation reaction interface regulation comprises the following steps:

[0008] (1) Molten salt synthesis of coated composite oxide powders

[0009] A new "silver salt-metal oxide" composite precursor system is prepared by high-energy ball milling using silver salt (Ag nitrate or Ag carbonate) and low-valent metal oxide MeO (SnO, FeO, Cu2O, one or more thereof) as raw materials. According to the mass ratio of silver salt to metal oxide (1-3):1, silver salt and low-valent metal oxide are placed in a planetary ball mill for wet ball milling. The ball milling medium is ethanol solvent (10%-20% of the total mass of the raw materials), the ball-to-material ratio is (10-20):1, the speed is 100-500rpm, the reaction time is 6h-24h, and the product after ball milling reaction is dried (drying temperature is 80-100℃) to obtain the corresponding "silver salt-low-valent metal oxide" composite precursor. The composite precursor synthesized above is used as a reactant and placed in a vacuum sintering furnace for molten salt thermal decomposition reaction. Since the melting point of silver salt is 200-250℃, within this temperature range, the silver salt in the composite precursor melts and fully covers the low-valent metal oxide. The temperature is further increased under vacuum conditions until it decomposes into metallic Ag, forming a coated Ag@MeO composite powder. The specific process is: vacuum degree 10 -5 ~10 -3 Pa, keep the temperature at 200-250℃ for 4-8h, continue to heat up to 440-500℃, and keep the temperature for 4-8h. After thermal decomposition of molten salt, the coated Ag@MeO composite powder is obtained, and the Ag content in the coated Ag@MeO composite powder is determined according to the chemical titration method of the national standard "GB / T 24268-2009".

[0010] (2) Preparation of silver-based composite ingots by hot pressing and sintering

[0011] According to the ratio of MeO to Ag (Ag content = Ag content in coated Ag@MeO composite powder + Ag content added in this step) (10~15): (90~85), weigh the corresponding Ag powder. The coated Ag@MeO composite powder and Ag powder are subjected to high-energy ball milling (the method is the same as in step (1)) to obtain a uniformly dispersed silver-based composite powder. The silver-based composite powder is introduced into a molding mold for hot pressing sintering. The specific conditions are: hot pressing temperature of 600~900℃, heating rate of 2~10℃ / min, pressure of 50~500MPa, and holding time of 10~30h. After hot pressing sintering, the corresponding silver-based composite ingot is obtained by naturally cooling to room temperature. The hot pressing sintering process can realize the in-situ disproportionation reaction of low-valent metal oxides in the silver matrix. The generated metal element undergoes atomic diffusion with Ag under high temperature and high pressure, and an alloy interface layer can be formed after a certain period of time. The interface bonding strength of the silver-based composite ingot was tested by hardness and tensile mechanical properties.

[0012] (3) Preparation of silver-based composite contact materials by multi-pass angle rolling process

[0013] Using silver-based composite ingots as raw materials, by adjusting the hot extrusion process parameters, the orientation distribution of oxide particles in the silver matrix can be controlled, and smooth extrusion can be achieved at a lower extrusion temperature. Combined with the inclination pressing, the required silver-based composite contact material can be obtained. Specifically, by controlling the hot extrusion process parameters, extrusion ratio (30~50):1, extrusion temperature (400~500℃), the extruded wire of the silver-based composite contact material is obtained. The extruded wire is rolled at multiple inclination angles, and the process parameters of each inclination rolling are adjusted, such as rolling deformation (2%~20%), rolling inclination (5°~90°), recrystallization annealing temperature (350~550℃), etc., to improve the grain uniformity, size and texture orientation distribution of the silver-based composite ingot, and prepare a silver-based composite contact material with no obvious texture bands in the internal structure and uniform grain size. After the corresponding composite contact material is prepared, its hardness, tensile mechanical properties and electrical life performance are tested. The test results show that the method of the present invention can obtain a silver-based composite contact material with high strength, toughness and corrosion resistance.

[0014] The inventive principle of the present invention is:

[0015] After high-energy ball milling, low-valent metal oxides and silver salts are evenly distributed, and subsequent temperature rise will cause the silver salt to melt. The two are fully infiltrated, so the coated Ag@MeO composite powder can be obtained after thermal decomposition of molten salt. During the hot pressing sintering process, MeO oxide powder will undergo a disproportionation reaction: 2MeO→Me+MeO2, and the generated metal element will undergo atomic diffusion with Ag under high temperature and high pressure, and an alloy interface layer can be formed after a certain period of time, which greatly improves the interface bonding strength between the coated metal oxide and Ag, and the Ag coating layer can form a good interface with the silver matrix. Compared with the method of introducing additives and surface coating modification, the process is simpler, the interface bonding strength is higher, and the effect of improving the arc erosion resistance is better. In addition, due to the formation of a strong interface bond, the processing performance of the hot extruded wire is improved, and the production cost is greatly reduced. The interfacial bonding strength determines whether the metal oxide will be segregated to the surface of the material. For example, if the interfacial bonding strength is low, the drag force of Ag / metal oxide inside the molten pool will be small. Under the action of gravity, due to the low density of the metal oxide, it will float to the surface of the material, resulting in serious metal oxide segregation and deterioration of material performance. The present invention utilizes molten salt thermal decomposition to form a coated Ag@MeO composite powder, combined with an interface control method of an in-situ disproportionation reaction, to form an alloy interface layer at the interface, significantly improving the interfacial bonding strength, while simplifying the process, achieving the results of cost reduction and efficiency improvement, and has great potential for industrial production.

[0016] Innovations and beneficial effects of the present invention:

[0017] 1. The coated Ag@MeO composite powder is formed by thermal decomposition of molten silver salt as an intermediate to prepare for the in-situ disproportionation reaction during hot pressing sintering. At the same time, the Ag coating layer and the silver matrix can form a good interface.

[0018] 2. By utilizing the in-situ disproportionation reaction, under certain temperature, pressure and time, Ag and metal elements form an alloy interface, which significantly improves the interface bonding strength and improves the arc erosion resistance.

[0019] 3. Compared with the non-reactive interface bonding by introducing additives, the interface bonding enhancement mechanism of the present invention is reactive interface bonding, that is, Ag and other metal elements form a new alloy phase, and the interface bonding strength enhancement effect is more prominent.

[0020] 4. Compared with the surface coating modification method involving problems such as non-environmentally friendly plating solution, difficulty in accurately controlling the thickness of the interface coating, and complex electroplating process, the method of the present invention greatly simplifies the process and has the advantages of environmental protection, low cost, and excellent performance.

[0021] 5. Compared with the conventional horizontal rolling process, the new multi-pass inclined rolling process proposed by the present invention regulates the plastic deformation ability of the silver-based composite contact material, realizes the effective regulation of the internal tissue uniformity of the material, and improves the strength and toughness of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 SEM and EDS pictures of the coated Ag@MeO composite powder obtained in Step 1 of Example 1;

[0023] Figure 2 XRD pattern of the alloy interface layer formed in Step 2 of Example 1;

[0024] Figure 3 a and b in the figure are the surface morphologies of the arc erosion of Example 1 and Comparative Example 1, respectively. DETAILED DESCRIPTION OF THE INVENTION

[0025] The implementation of the present invention will be described exemplarily below through specific embodiments.

[0026] Example 1

[0027] The steps for preparing the silver-based composite contact material in this example are as follows:

[0028] (1) Synthesis of coated Ag@SnO composite powder by molten salt method

[0029] Weigh 60 g of AgNO3 and 30 g of SnO and put them into a planetary ball mill for wet ball milling. Add 15 g of ethanol solvent, with a ball-to-material ratio of 15:1, a rotation speed of 300 rpm, and a reaction time of 18 h. The product after ball milling reaction is dried at 80 °C to obtain the corresponding "AgNO3-SnO" composite precursor. Using the synthesized "AgNO3-SnO" composite precursor as the reactant, place it in a vacuum sintering furnace for molten salt thermal decomposition reaction. The specific process is as follows: vacuum degree 10 -5 MPa, keep the temperature at 220 °C for 6 h, continue to heat up to 450 °C, and keep the temperature for 6 h to obtain the coated Ag@SnO composite powder, as Figure 1 shown, and determine the Ag content in the coated Ag@SnO composite powder by chemical titration method according to the national standard "GB / T 24268-2009", and obtain the Ag mass of 35 g.

[0030] (2) Preparation of silver-based composite ingot by hot pressing sintering method

[0031] Using the coated Ag@SnO composite powder as an intermediate and Ag powder as the raw material, with the ratio of SnO to the total Ag powder being 12:88, the mass of the total Ag powder is calculated as 30 / 0.12 - 30 = 220 g. Then, 220 - 35 = 185 g of the corresponding Ag powder is weighed. The coated Ag@SnO composite powder and Ag powder are subjected to high-energy ball milling (the ball milling method and steps are the same as in (1)) to obtain a uniformly dispersed silver-based composite powder. The silver-based composite powder is introduced into a molding die for hot pressing sintering. The specific conditions are as follows: hot pressing temperature 700 °C, heating rate 5 °C / min, pressure 300 MPa, and holding time 20 h. After hot pressing sintering, it is naturally cooled to room temperature to obtain the corresponding silver-based composite ingot. Through XRD testing, an Ag3Sn alloy interface layer is formed, and Sn elemental substance is detected, as Figure 2 shown.

[0032] (3)Preparation of the silver-based composite contact material by multi-pass inclined rolling process

[0033] Using the silver-based composite ingot as the raw material, by controlling the extrusion ratio of 40:1 and the extrusion temperature of 450 °C, a silver-based composite contact material extrusion wire is obtained after hot extrusion. Then, the extrusion wire is subjected to 8-pass inclined rolling. The inclined rolling parameters for each pass are set as rolling deformation (5%), rolling inclination angle (10°), and recrystallization annealing temperature (450 °C) to prepare the corresponding composite contact material, and its hardness, tensile mechanical properties, and electrical life performance are tested.

[0034] Example 2

[0035] The steps for preparing the silver-based composite contact material in this example are as follows:

[0036] (1)Synthesis of the coated Ag@FeO composite powder by molten salt method

[0037] Weigh 30 g of Ag2CO3 and 30 g of FeO and put them into a planetary ball mill for wet ball milling. Add 6 g of ethanol solvent, with a ball-to-material ratio of 10:1, a rotation speed of 100 rpm, and a reaction time of 24 h. The product after ball milling reaction is dried to obtain the corresponding "Ag2CO3 - FeO" composite precursor. Using the above-synthesized "Ag2CO3 - FeO" composite precursor as the reactant, it is placed in a vacuum sintering furnace for molten salt thermal decomposition reaction. The specific process is as follows: vacuum degree 10 -3 MPa, hold at 200 °C for 4 h, continue to heat up to 440 °C, and hold for 4 h to obtain the coated Ag@FeO composite powder. According to the national standard "GB / T 24268 - 2009" chemical titration method, the Ag content in the coated Ag@FeO composite powder is measured, and the mass of Ag is obtained as 20 g.

[0038] (2)Preparation of the silver-based composite ingot by hot pressing sintering method

[0039] Using the coated Ag@FeO composite powder as an intermediate and Ag powder as the raw material, with the ratio of FeO to the total Ag powder being 10:90, the mass of the total Ag powder is calculated as 30 / 0.1 - 30 = 270 g. Then, 270 - 20 = 250 g of the corresponding Ag powder is weighed. The coated Ag@FeO composite powder and Ag powder are subjected to high-energy ball milling (the ball milling method and steps are the same as in (1)) to obtain a uniformly dispersed silver-based composite powder. The silver-based composite powder is introduced into a molding die for hot pressing sintering. The specific conditions are: hot pressing temperature 600 °C, heating rate 2 °C / min, pressure 500 MPa, and holding time 10 h. After hot pressing sintering, it is naturally cooled to room temperature to obtain the corresponding silver-based composite ingot.

[0040] (3)Preparation of silver-based composite contact materials by multi-pass inclined rolling process

[0041] Using the silver-based composite ingot as the raw material, by controlling the extrusion ratio of 30:1 and the extrusion temperature of 400 °C, a silver-based composite contact material extrusion wire is obtained after hot extrusion. The extrusion wire is subjected to 7-pass inclined rolling. By setting the process parameters of each pass of inclined rolling as the rolling deformation amount (2%), the rolling inclination angle (5°), and the recrystallization annealing temperature (350 °C), a silver-based composite contact material with no obvious texture band and uniform grain size in the internal structure is prepared, and its hardness, tensile mechanical properties, and electrical life performance are tested.

[0042] Example 3

[0043] The steps for preparing the silver-based composite contact material in this example are as follows:

[0044] (1)Synthesis of coated Ag@Cu2O composite powder by molten salt method

[0045] Weigh 90 g of AgNO3 and 30 g of Cu2O and put them into a planetary ball mill for wet ball milling. Add 24 g of ethanol solvent, with a ball-to-material ratio of 20:1 and a rotation speed of 500 rpm. The reaction time is 6 h. The product after ball milling reaction is dried to obtain the corresponding "AgNO3-Cu2O" composite precursor. Using the synthesized "AgNO3-Cu2O" composite precursor as the reactant, it is placed in a vacuum sintering furnace for molten salt thermal decomposition reaction. The specific process is: vacuum degree 10 -5 MPa, hold at 250 °C for 8 h, continue to heat up to 500 °C, and hold for 8 h to obtain the coated Ag@Cu2O composite powder. The Ag content in the coated Ag@Cu2O composite powder is determined by chemical titration method according to the national standard "GB / T 24268-2009", and the mass of Ag is obtained as 50 g.

[0046] (2)Preparation of silver-based composite ingot by hot pressing sintering method

[0047] Using the coated Ag@Cu2O composite powder as an intermediate and Ag powder as the raw material, with the ratio of Cu2O to the total Ag powder being 15:85, the mass of the total Ag powder is calculated as 30 / 0.15 - 30 = 170 g. Then, 170 - 50 = 120 g of the corresponding Ag powder is weighed. The coated Ag@Cu2O composite powder and Ag powder are subjected to high-energy ball milling (the ball milling method and steps are the same as in (1)) to obtain a uniformly dispersed silver-based composite powder. The silver-based composite powder is introduced into a forming die for hot pressing sintering. The specific conditions are as follows: hot pressing temperature 900 °C, heating rate 10 °C / min, pressure 50 MPa, and holding time 30 h. After hot pressing sintering, it is naturally cooled to room temperature to obtain the corresponding silver-based composite ingot.

[0048] (3)Preparation of silver-based composite contact materials by multi-pass inclined rolling process

[0049] Using the silver-based composite ingot as the raw material, by controlling the extrusion ratio of 50:1 and the extrusion temperature of 500 °C, a silver-based composite contact material extrusion wire is obtained after hot extrusion. The extrusion wire is subjected to 9-pass inclined rolling. By setting the parameters of each pass of inclined rolling as the rolling deformation amount (20%), the rolling inclination angle (90°), and the recrystallization annealing temperature (550 °C), the corresponding composite contact material is prepared, and its hardness, tensile mechanical properties, and electrical life performance are tested.

[0050] Example 4

[0051] The steps for preparing the silver-based composite contact material in this example are as follows:

[0052] (1)Synthesis of coated composite Ag@SnO / FeO powder by molten salt method

[0053] Weigh 60 g of AgNO3, 20 g of SnO, and 10 g of FeO and put them into a planetary ball mill for wet ball milling. Add 15 g of ethanol solvent, with a ball-to-material ratio of 15:1, a rotation speed of 300 rpm, and a reaction time of 18 h. The product after ball milling reaction is dried to obtain the corresponding "AgNO3 - SnO / FeO" composite precursor. Using the synthesized "AgNO3 - SnO / FeO" composite precursor as the reactant, it is placed in a vacuum sintering furnace for molten salt thermal decomposition reaction. The specific process is as follows: vacuum degree 10 -5 MPa, hold at 220 °C for 6 h, continue to heat up to 450 °C, and hold for 6 h to obtain the coated Ag@SnO / FeO composite powder. According to the national standard "GB / T24268 - 2009" chemical titration method, the Ag content in the coated Ag@SnO / FeO composite powder is measured, and the mass of Ag is obtained as 35 g.

[0054] (2)Preparation of silver-based composite ingot by hot pressing sintering method

[0055] Using the coated Ag@SnO / FeO composite powder as an intermediate and Ag powder as the raw material, with the ratio of SnO / FeO to the total Ag powder being 12:88, the mass of the total Ag powder is calculated as 30 / 0.12 - 30 = 220 g. Then, 220 - 35 = 185 g of the corresponding Ag powder is weighed. High-energy ball milling (the same ball milling method and steps as in (1)) is used to obtain a uniformly dispersed silver-based composite powder. The silver-based composite powder is introduced into a molding die for hot pressing sintering. The specific conditions are: hot pressing temperature 700 °C, heating rate 5 °C / min, pressure 300 MPa, and holding time 20 h. After hot pressing sintering, it is naturally cooled to room temperature to obtain the corresponding silver-based composite ingot.

[0056] (3) Preparation of silver-based composite contact materials by multi-pass inclined rolling process

[0057] Using the silver-based composite ingot as the raw material, by controlling the extrusion ratio of 40:1 and the extrusion temperature of 450 °C, a silver-based composite contact material extrusion wire is obtained after hot extrusion. Then, the extrusion wire is subjected to 8-pass inclined rolling. The process parameters of each pass of inclined rolling are set, including rolling deformation (5%), rolling inclination angle (10°), and recrystallization annealing temperature (450 °C) to prepare the corresponding composite contact material, and its hardness, tensile mechanical properties, and electrical life performance are tested.

[0058] Comparative Example 1

[0059] In this comparative example, a silver-based electrical contact material is prepared by a method without disproportionation reaction and introducing SnO2 additive:

[0060] (1) Preparation of composite powder by powder metallurgy method

[0061] Weigh and put Ag and SnO2 in a planetary ball mill according to the mass ratio of Ag:SnO2 = 88:12, add ethanol, with a ball-to-material ratio of 15:1, a rotation speed of 300 rpm, and a time of 18 h. After drying, the composite powder is obtained.

[0062] (2) Preparation of silver-based electrical contact materials by multi-pass inclined rolling process

[0063] The obtained composite powder is subjected to hot pressing sintering. The specific conditions are: temperature 700 °C, heating rate 5 °C / min, pressure 300 MPa, and holding time 20 h. After hot pressing sintering, it is naturally cooled to room temperature to obtain the corresponding silver-based composite ingot. By controlling the extrusion ratio of 40:1 and the extrusion temperature of 450 °C, a silver-based composite contact material extrusion wire is obtained after hot extrusion. The extrusion wire is subjected to 8-pass inclined rolling. By setting the inclined rolling parameters of each pass, including rolling deformation (5%), rolling inclination angle (10°), and recrystallization annealing temperature (450 °C), the corresponding composite contact material is prepared.

[0064] Comparative Example 2

[0065] This comparative example uses a method of preparing a silver-based electrical contact material without disproportionation reaction and introducing Fe3O4 additive:

[0066] (1)Preparation of composite powder by powder metallurgy

[0067] Weigh Ag and Fe3O4 according to the mass ratio of Ag:Fe3O4 = 90:10, put them into a planetary ball mill, add ethanol, the ball-to-material ratio is 10:1, the rotation speed is 100 rpm, and the time is 24 h. After drying, the composite powder is obtained.

[0068] (2)Preparation of silver-based electrical contact material by multi-pass inclined rolling process

[0069] The obtained composite powder is subjected to hot press sintering. The specific conditions are: temperature 600 °C, heating rate 2 °C / min, pressure 500 MPa, holding time 10 h. After hot press sintering, it is naturally cooled to room temperature to obtain the corresponding silver-based composite ingot. By controlling the extrusion ratio of 30:1 and the extrusion temperature of 400 °C, the silver-based composite contact material extrusion wire is obtained by hot extrusion. The extrusion wire is subjected to 7-pass inclined rolling. By setting the parameters of each pass of inclined rolling, including the rolling deformation amount (2%), the rolling inclination angle (5°), and the recrystallization annealing temperature (350 °C), the corresponding composite contact material is prepared.

[0070] Comparative Example 3

[0071] This comparative example uses a method of preparing a silver-based electrical contact material without disproportionation reaction and introducing CuO additive:

[0072] (1)Preparation of composite powder by powder metallurgy

[0073] Weigh Ag and CuO according to the mass ratio of Ag:CuO = 85:15, put them into a planetary ball mill, add ethanol, the ball-to-material ratio is 20:1, the rotation speed is 500 rpm, and the time is 6 h. After drying, the composite powder is obtained.

[0074] (2)Preparation of silver-based electrical contact material by multi-pass inclined rolling process

[0075] The obtained composite powder is subjected to hot press sintering. The specific conditions are: temperature 900 °C, heating rate 10 °C / min, pressure 50 MPa, holding time 30 h. After hot press sintering, it is naturally cooled to room temperature to obtain the corresponding silver-based composite ingot. By controlling the extrusion ratio of 50:1 and the extrusion temperature of 500 °C, the silver-based composite contact material extrusion wire is obtained by hot extrusion. The extrusion wire is subjected to 9-pass inclined rolling. By setting the parameters of each pass of inclined rolling as the rolling deformation amount (20%), the rolling inclination angle (90°), and the recrystallization annealing temperature (550 °C), the corresponding composite contact material is prepared.

[0076] Comparative Example 4

[0077] This comparative example uses a method of preparing a silver-based electrical contact material without disproportionation reaction and introducing SnO2 / Fe3O4 additives:

[0078] (1) Preparation of composite powder by powder metallurgy method

[0079] Weigh according to the mass ratio of Ag: SnO2:Fe3O4 = 88:8:4 and put them into a planetary ball mill, add ethanol, with a ball-to-material ratio of 15:1, a rotation speed of 300 rpm, and a time of 18 h. After drying, the composite powder is obtained.

[0080] (2) Preparation of silver-based electrical contact material by multi-pass inclined rolling process

[0081] The obtained composite powder is subjected to hot pressing and sintering. The specific conditions are: temperature 700 °C, heating rate 5 °C / min, pressure 300 MPa, and holding time 20 h. After hot pressing and sintering, it is naturally cooled to room temperature to obtain the corresponding silver-based composite ingot. By controlling the extrusion ratio of 40:1 and the extrusion temperature of 450 °C, the silver-based composite contact material extrusion wire is obtained by hot extrusion. The extrusion wire is subjected to 8-pass inclined rolling. By setting the parameters of each pass of inclined rolling as the rolling deformation amount (5%), the rolling inclination angle (10°), and the recrystallization annealing temperature (450 °C), the corresponding composite contact material is prepared.

[0082] The electrical performance characterization of the silver-based electrical contact materials prepared in the above Examples 1-4 and Comparative Examples 1-4 is shown in Table 1.

[0083] Table 1 Interface strength and electrical performance of silver-based electrical contact materials

[0084]

[0085] After testing, the method of the present invention has more prominent effects in enhancing the interface bonding strength, a simple process, environmental protection, low cost, excellent anti-arc erosion performance, excellent hardness and tensile strength, and also has good elongation and a long cycle life and other performance advantages. Compared with Comparative Example 1 (see Figure 3 b therein), after arc erosion, the surface erosion of Example 1 (see Figure 3 a therein) is smoother, so it shows better anti-arc erosion behavior. Therefore, the product prepared by the method of the present invention has excellent comprehensive performance and can be applied in the fields of photovoltaic wind power, new energy vehicles, high-power charging piles, etc., and has broad prospects.

Claims

1. A preparation method of a silver-based composite material based on in-situ disproportionation reaction interface regulation, characterized in that, It includes the following steps: (1) Using silver salts and low-valent metal oxides as raw materials, a new system of "silver salt - low-valent metal oxide" composite precursor is prepared by high-energy ball milling; wherein, the low-valent metal oxide is one or more of SnO, FeO, and Cu2O, and the mass ratio of silver salt to metal oxide is (1~3):1; the product after the high-energy ball milling reaction is dried to obtain the "silver salt - low-valent metal oxide" composite precursor; the "silver salt - low-valent metal oxide" composite precursor is placed in a vacuum sintering furnace for molten salt thermal decomposition reaction to obtain a coated Ag@ Me O composite powder, and the Ag content in the coated Ag@ Me O composite powder is determined by the chemical titration method according to the national standard "GB / T 24268-2009". (2)Taking the coated Ag@ Me O composite powder and Ag powder as raw materials, a uniformly dispersed silver-based composite powder is obtained by high-energy ball milling. The mass ratio of Me O to Ag in the silver-based composite powder is (10~15):(90~85); the silver-based composite powder is introduced into a molding die for hot press sintering, and then naturally cooled to room temperature to obtain a silver-based composite ingot; Using a silver-based composite ingot as raw material, an extruded wire is obtained through hot extrusion. The extruded wire undergoes several angle rolling processes to achieve controllable orientation distribution of oxide particles in the silver matrix, thereby obtaining a silver-based composite contact material.

2. The preparation method of a silver-based composite material based on in-situ disproportionation reaction interface regulation according to claim 1, wherein, The silver salt is silver nitrate or silver carbonate.

3. A method for preparing a silver-based composite material based on in-situ disproportionation reaction interface regulation according to claim 1, characterized in that, In steps (1) and (2), the specific method of high-energy ball milling is as follows: The raw materials are put into a planetary ball mill for wet ball milling. The ball milling medium is an ethanol solvent, the ball-to-material ratio is (10~20):1, the rotation speed is 100~500 rpm, and the reaction time is 6h~24h.

4. The preparation method of a silver-based composite material based on in-situ disproportionation reaction interface regulation according to claim 1, characterized in that In step (1), the specific process of the molten salt thermal decomposition reaction is as follows: the vacuum degree is 10 -5 ~10 -3 Pa, keep the temperature at 200 - 250 °C for 4 - 8 h, then continue to heat up to 440 - 500 °C and keep the temperature for 4 - 8 h.

5. The preparation method of a silver-based composite material based on in-situ disproportionation reaction interface regulation according to claim 1, characterized in that, In step (2), the specific conditions of hot press sintering are: hot press temperature 600~900°C, heating rate 2~10°C / min, pressure 50~500 MPa, and heat preservation time 10~30h.

6. A method for preparing a silver-based composite material based on in-situ disproportionation reaction interface regulation according to claim 1, characterized in that, In step (3), the process parameters of the hot extrusion include: extrusion ratio 30~50:1, extrusion temperature 400~500°C; the process parameters of each angle rolling are specifically: rolling deformation 2%~20%, rolling angle 5°~90°, and recrystallization annealing temperature 350~550°C.

7. A silver-based composite material based on in-situ disproportionation reaction interface regulation, characterized in that, It is prepared by using the method according to any one of claims 1-6.

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