Preparation method of silver-based composite materials based on in-situ disproportionation reaction interface regulation

Abstract

The present invention discloses a method for preparing a silver-based composite material based on in-situ disproportionation reaction interface regulation. The method constructs a new "silver salt-low-valent metal oxide" composite precursor system and uses molten salt thermal decomposition to prepare coated Ag@ Me O composite powder; then, through a hot pressing and sintering process, an in-situ disproportionation reaction of low-valent metal oxides in the silver matrix is achieved. The resulting metal element forms an alloy interface with Ag, resulting in a silver-based composite ingot with strong interfacial bonding, excellent tensile strength and elongation. Combining hot extrusion technology with angled rolling, and by regulating the hot extrusion and multi-pass angled rolling process parameters, the orientation distribution of the oxide particles in the silver matrix is controlled, resulting in a high-strength, toughness, and corrosion-resistant silver-based composite contact material. The method of the present invention is simple, environmentally friendly, and low-cost, with great potential for industrial production.

Description

Technical Field

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

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

[0003] At present, researchers mainly use the methods of introducing additives and surface coating modification to improve the interfacial bonding strength. For example, in the Ag / SnO2 material with the addition of CuO, no SnO2-rich layer is found in the remelting area, and the SnO2 particles remain 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 interfacial bonding is non-reactive wetting, which has little effect on enhancing the arc erosion resistance. Researchers use chemical plating to deposit Ag on the surface of titanium-doped SnO2 particles, achieving a uniform distribution of Ag-deposited SnO2 particles in the silver matrix, improving the interfacial bonding strength between Ag and SnO2, and improving the electrical conductivity, hardness and thermal stability of the Ag / SnO2 material. However, the chemical plating method is costly, the process is complex, and it is difficult to accurately control 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 addressed by the present invention is to provide a method for preparing silver-based composite materials based on in-situ disproportionation reaction interface control. This method uses low-valent metal oxides as the second phase and utilizes thermal decomposition of molten silver salts to form a coated composite oxide powder. The low-valent metal oxides undergo a disproportionation reaction under vacuum hot pressing to form a metal element. The metal element diffuses with Ag at a specific pressure and temperature to form an alloy layer, significantly improving the interfacial bonding strength and enhancing 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 silver-based composite materials based on in-situ disproportionation reaction interface control is described. The method involves first constructing a new "silver salt-low-valent metal oxide" composite precursor system and producing a coated composite oxide powder using molten salt thermal decomposition. Then, through a hot pressing and sintering process, an in-situ disproportionation reaction of the low-valent metal oxide in the silver matrix is achieved. The resulting metal element diffuses with Ag at a certain pressure and temperature to form an alloy layer, significantly improving the interfacial bonding strength. Combined with hot extrusion and multi-pass angle rolling, the orientation distribution of the oxide particles in the silver matrix is controlled, allowing for smooth extrusion at relatively low extrusion temperatures, significantly enhancing 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 was prepared using silver salt (either Ag nitrate or Ag carbonate) and low-valent metal oxide MeO (one or more of SnO, FeO, or CuO) as raw materials via high-energy ball milling. The silver salt and low-valent metal oxide were wet-milled in a planetary ball mill at a silver salt to metal oxide mass ratio of 1-3:1. The milling medium was ethanol (10%-20% of the total raw material mass), the ball-to-material ratio was 10-20:1, the speed was 100-500 rpm, and the reaction time was 6-24 hours. The milled product was then dried at 80-100°C to obtain the corresponding "silver salt-low-valent metal oxide" composite precursor. The synthesized composite precursor was then placed in a vacuum sintering furnace for molten salt thermal decomposition. 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. Under vacuum conditions, the temperature is further increased until it decomposes into metallic Ag, forming a coated Ag@MeO composite powder. The specific process is: vacuum degree 10 -5 ~10 -3 Pa, maintained at 200-250°C for 4-8 hours, then continued to heat to 440-500°C and maintained for 4-8 hours. After thermal decomposition of the molten salt, the coated Ag@MeO composite powder was obtained. The Ag content in the coated Ag@MeO composite powder was determined according to the chemical titration method in accordance with 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), the corresponding amount of Ag powder is weighed. 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 forming mold for hot pressing and sintering. The specific conditions are: hot pressing temperature 600~900℃, heating rate 2~10℃ / min, pressure 50~500MPa, holding time 10~30h, and naturally cooled to room temperature after hot pressing and sintering to obtain the corresponding silver-based composite ingot. The hot pressing and 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 ingots was tested for 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, the hot extrusion process parameters are controlled to achieve controllable orientation distribution of oxide particles in the silver matrix. This allows for smooth extrusion at relatively low extrusion temperatures, combined with angled pressing to produce the desired silver-based composite contact material. Specifically, by controlling the hot extrusion process parameters, including an extrusion ratio (30-50):1 and an extrusion temperature (400-500°C), the extruded wire of the silver-based composite contact material is obtained. The extruded wire undergoes multiple passes of angled rolling, with the process parameters of each angle rolling being controlled, including the rolling deformation (2%-20%), rolling angle (5°-90°), and recrystallization annealing temperature (350-550°C). This improves the grain uniformity, size, and texture orientation distribution of the silver-based composite ingot, resulting in a silver-based composite contact material with uniform grain size and no obvious texture banding within the internal structure. 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, the low-valent metal oxide and silver salt are evenly distributed. Subsequent heating causes the silver salt to melt, fully infiltrating the two. Consequently, a coated Ag@MeO composite powder is obtained after thermal decomposition of the molten salt. During hot pressing and sintering, the MeO oxide powder undergoes a disproportionation reaction: 2MeO → Me + MeO2. The resulting metal element undergoes atomic diffusion with Ag under high temperature and pressure, forming an alloy interface layer over a period of time. This significantly enhances the interfacial bonding strength between the coated metal oxide and Ag, and forms a good interface between the Ag coating and the silver substrate. Compared to methods involving additives and surface coating modifications, this method is simpler, achieves higher interfacial bonding strength, and achieves better arc erosion resistance. Furthermore, this strong interfacial bonding improves the processing performance of hot-extruded wires, significantly reducing production costs. The interfacial bonding strength determines whether the metal oxide will segregate to the material surface. Weak interfacial bonding strength results in low drag force on the Ag / metal oxide within the molten pool. Under the influence of gravity, the metal oxide, due to its low density, floats to the material surface, causing severe metal oxide segregation and deteriorating material properties. This invention utilizes molten salt thermal decomposition to form a coated Ag@MeO composite powder. Combined with an in-situ disproportionation reaction interface control method, an alloy interface layer is formed at the interface, significantly improving interfacial bonding strength while simplifying the process, achieving cost reduction and efficiency improvement, and possessing 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, preparing for the in-situ disproportionation reaction during hot pressing sintering. At the same time, the Ag coating layer can form a good interface with the silver substrate.

[0018] 2. By utilizing 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 method of 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 being environmentally friendly, low cost, and excellent performance.

[0021] 5. Compared with the conventional horizontal rolling process, the new multi-pass angled rolling process proposed in this invention regulates the plastic deformation ability of the silver-based composite contact material, effectively adjusts the uniformity of the material's internal structure, and improves the material's strength and toughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The SEM and EDS images of the coated Ag@MeO composite powder obtained in step 1 of Example 1 are shown;

[0023] Figure 2 The XRD pattern of the alloy interface layer is generated in step 2 of Example 1;

[0024] Figure 3 a and b are arc erosion surface morphologies of Example 1 and Comparative Example 1, respectively. DETAILED DESCRIPTION

[0025] The following is an exemplary description of the implementation of the present invention through specific embodiments.

[0026] Example 1

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

[0028] (1) Molten salt synthesis of coated Ag@SnO composite powders

[0029] Weigh 60g AgNO3 and 30g SnO and place them in a planetary ball mill for wet ball milling. Add 15g ethanol solvent, set the ball-to-material ratio at 15:1, rotate at 300rpm, and react for 18h. The product after ball milling is dried at 80℃ to obtain the corresponding "AgNO3-SnO" composite precursor. The "AgNO3-SnO" composite precursor synthesized above is used as the reactant and placed in a vacuum sintering furnace for molten salt thermal decomposition reaction. The specific process is as follows: vacuum degree 10 -5 MPa, kept at 220℃ for 6h, then continued to heat up to 450℃ and kept for 6h to obtain coated Ag@SnO composite powder, such as Figure 1 As shown, the Ag content in the coated Ag@SnO composite powder was determined by chemical titration according to the national standard "GB / T 24268-2009", and the Ag mass was 35g.

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

[0031] Using coated Ag@SnO composite powder as the intermediate and Ag powder as the raw material, according to the ratio of SnO to total Ag powder of 12:88, the total Ag powder mass is 30 / 0.12-30=220g, and the corresponding Ag powder amount is calculated and weighed as 220-35=185g. The coated Ag@SnO composite powder and Ag powder are subjected to high-energy ball milling (the ball milling method is the same as step (1)) to obtain uniformly dispersed silver-based composite powder. The silver-based composite powder is introduced into a molding mold for hot pressing and sintering. The specific conditions are: hot pressing temperature 700℃, heating rate 5℃ / min, pressure 300MPa, holding time 20h, and naturally cooled to room temperature after hot pressing and sintering to obtain the corresponding silver-based composite ingot. XRD test shows that an Ag3Sn alloy interface layer is generated, and Sn element is detected, such as Figure 2 shown.

[0032] (3) Preparation of silver-based composite contact materials by multi-pass angle rolling process

[0033] Using silver-based composite ingots as raw materials, by controlling the extrusion ratio of 40:1 and the extrusion temperature of 450℃, silver-based composite contact material extruded wires were obtained after hot extrusion. Then the extruded wires were subjected to 8 passes of angle rolling. The angle rolling parameters of each pass were set as rolling deformation (5%), rolling angle (10°), and recrystallization annealing temperature (450℃) to prepare the corresponding composite contact materials, and their hardness, tensile mechanical properties and electrical life performance were tested.

[0034] Example 2

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

[0036] (1) Molten salt synthesis of coated Ag@FeO composite powders

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

[0038] (2) Preparation of silver-based composite ingots by hot pressing and sintering

[0039] Using coated Ag@FeO composite powder as the intermediate and Ag powder as the raw material, the total Ag powder mass is 30 / 0.1-30=270g according to the ratio of FeO to total Ag powder of 10:90. The corresponding amount of Ag powder is calculated and weighed as 270-20=250g. The coated Ag@FeO composite powder and Ag powder are subjected to high-energy ball milling (the ball milling method is the same as step (1)) to obtain a uniformly dispersed silver-based composite powder. The silver-based composite powder is introduced into a forming mold for hot pressing and sintering. The specific conditions are: hot pressing temperature of 600℃, heating rate of 2℃ / min, pressure of 500MPa, holding time of 10h, and natural cooling to room temperature after hot pressing and sintering to obtain the corresponding silver-based composite ingot.

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

[0041] Using silver-based composite ingots as raw materials, by controlling the extrusion ratio to 30:1 and the extrusion temperature to 400℃, silver-based composite contact material extruded wires were obtained after hot extrusion. The extruded wires were subjected to 7 passes of angle rolling. By setting the process parameters of each pass of angle rolling to rolling deformation (2%), rolling angle (5°), and recrystallization annealing temperature (350℃), a silver-based composite contact material with no obvious texture bands in the internal structure and uniform grain size was prepared. Its hardness, tensile mechanical properties and electrical life performance were tested.

[0042] Example 3

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

[0044] (1) Molten salt synthesis of coated Ag@Cu2O composite powders

[0045] Weigh 90g AgNO3 and 30g Cu2O and place them in a planetary ball mill for wet ball milling. Add 24g ethanol solvent, set the ball-to-material ratio at 20:1, rotate at 500rpm, and react for 6h. After ball milling, dry the product to obtain the corresponding "AgNO3-Cu2O" composite precursor. The "AgNO3-Cu2O" composite precursor synthesized above is used as the reactant and placed in a vacuum sintering furnace for molten salt thermal decomposition reaction. The specific process is as follows: vacuum degree 10 -5 MPa, kept at 250 ° C for 8 h, and then continued to heat up to 500 ° C and kept for 8 h to obtain coated Ag@Cu2O composite powder. The Ag content in the coated Ag@Cu2O composite powder was determined by chemical titration according to the national standard "GB / T 24268-2009", and the Ag mass was 50 g.

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

[0047] Using coated Ag@Cu2O composite powder as the intermediate and Ag powder as the raw material, the total Ag powder mass is 30 / 0.15-30=170g according to the ratio of Cu2O to total Ag powder of 15:85. The corresponding amount of Ag powder is calculated and weighed as 170-50=120g. The coated Ag@Cu2O composite powder and Ag powder are subjected to high-energy ball milling (the ball milling method is the same as step (1)) to obtain a uniformly dispersed silver-based composite powder. The silver-based composite powder is introduced into a forming mold for hot pressing and sintering. The specific conditions are: hot pressing temperature 900℃, heating rate 10℃ / min, pressure 50MPa, holding time 30h, and natural cooling to room temperature after hot pressing and sintering to obtain the corresponding silver-based composite ingot.

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

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

[0050] Example 4

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

[0052] (1) Molten salt synthesis of coated composite Ag@SnO / FeO powder

[0053] Weigh 60g AgNO3, 20g SnO, and 10g FeO and place them in a planetary ball mill for wet ball milling. Add 15g ethanol solvent, set the ball-to-material ratio at 15:1, rotate at 300rpm, and react for 18h. The product after ball milling is dried to obtain the corresponding "AgNO3-SnO / FeO" composite precursor. The "AgNO3-SnO / FeO" composite precursor synthesized above is used as the reactant and placed in a vacuum sintering furnace for molten salt thermal decomposition reaction. The specific process is as follows: vacuum degree 10 -5 MPa, kept at 220 ° C for 6 h, continued to heat up to 450 ° C, and kept for 6 h to obtain coated Ag@SnO / FeO composite powder, and the Ag content in the coated Ag@SnO / FeO composite powder was determined according to the chemical titration method of the national standard "GB / T24268-2009", and the Ag mass was 35 g.

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

[0055] Using coated Ag@SnO / FeO composite powder as the intermediate and Ag powder as the raw material, the total Ag powder mass is 30 / 0.12-30=220g according to the ratio of SnO / FeO to total Ag powder of 12:88. The corresponding amount of Ag powder is calculated and weighed as 220-35=185g. High-energy ball milling (the ball milling method is the same as step (1)) is used to obtain uniformly dispersed silver-based composite powder. The silver-based composite powder is introduced into a forming mold for hot pressing and sintering. The specific conditions are: hot pressing temperature 700℃, heating rate 5℃ / min, pressure 300MPa, holding time 20h, and natural cooling to room temperature after hot pressing and sintering to obtain the corresponding silver-based composite ingot.

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

[0057] Using silver-based composite ingots as raw materials, by controlling the extrusion ratio at 40:1 and the extrusion temperature at 450°C, silver-based composite contact material extruded wires were obtained after hot extrusion. The extruded wires were then subjected to 8 passes of angle rolling. The process parameters of each pass of angle rolling were set, including rolling deformation (5%), rolling angle (10°), and recrystallization annealing temperature (450°C), to prepare the corresponding composite contact materials, and their hardness, tensile mechanical properties, and electrical life performance were tested.

[0058] Comparative Example 1

[0059] This comparative example uses a method without disproportionation reaction and introduction of SnO2 additive to prepare silver-based electrical contact materials:

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

[0061] Ag:SnO2 = 88:12 by mass was weighed and placed in a planetary ball mill. Ethanol was added, the ball-to-material ratio was 15:1, the rotation speed was 300 rpm, and the time was 18 hours. After drying, a composite powder was obtained.

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

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

[0064] Comparative Example 2

[0065] This comparative example uses a method without disproportionation reaction and introduction of Fe3O4 additives to prepare silver-based electrical contact materials:

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

[0067] Ag:Fe3O4 = 90:10 by mass was weighed and placed in a planetary ball mill. Ethanol was added, and the ball-to-material ratio was 10:1. The milling speed was 100 rpm and the milling time was 24 hours. After drying, a composite powder was obtained.

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

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

[0070] Comparative Example 3

[0071] This comparative example uses a method without disproportionation reaction and introduction of CuO additive to prepare silver-based electrical contact materials:

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

[0073] Ag:CuO = 85:15 by mass was weighed and placed in a planetary ball mill. Ethanol was added, the ball-to-material ratio was 20:1, the rotation speed was 500 rpm, and the time was 6 hours. After drying, a composite powder was obtained.

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

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

[0076] Comparative Example 4

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

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

[0079] Ag: SnO2: Fe3O4 (mass ratio 88:8:4) was weighed and placed in a planetary ball mill. Ethanol was added, and the milling time was 18 hours at a ball-to-material ratio of 15:1. The milling speed was 300 rpm. After drying, a composite powder was obtained.

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

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

[0082] The electrical properties of the silver-based electrical contact materials prepared in Examples 1-4 and Comparative Examples 1-4 are shown in Table 1.

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

[0084]

[0085] After testing, the method of the present invention has more prominent effect on enhancing the interface bonding strength, simple process, environmental protection, low cost, excellent arc erosion resistance, excellent hardness and tensile strength, good elongation, and long cycle life. Compared with comparative example 1 (see Figure 3 b), Example 1 after arc erosion (see Figure 3 The surface erosion in (a) is smoother, thus exhibiting better resistance to arc erosion. Therefore, the product produced by the method of the present invention has excellent overall performance and is suitable for application in photovoltaic and wind power generation, new energy vehicles, high-power charging piles, and other fields, showing broad prospects.

Claims

1. A method for preparing a silver-based composite material based on in-situ disproportionation reaction interface regulation, characterized in that: The following steps are involved: (1) Using silver salt and low-valent metal oxide as raw materials, a new "silver salt-low-valent metal oxide" composite precursor system 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 high-energy ball milling reaction is dried to obtain a "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 coated Ag@ Me O composite powder, and the coated Ag@ was determined according to the national standard "GB / T 24268-2009" chemical titration method Me Ag content in O composite powder; (2) The coated Ag@ Me O composite powder and Ag powder are used as raw materials, and high-energy ball milling is used to obtain uniformly dispersed silver-based composite powder. Me The mass ratio of O to Ag is (10-15): (90-85); the silver-based composite powder is introduced into a forming mold for hot pressing and sintering, and then naturally cooled to room temperature to obtain a silver-based composite ingot; Silver-based composite ingots are used as raw materials, and extruded wires are obtained by hot extrusion. The extruded wires are subjected to several times of angle rolling to achieve controllable orientation distribution of oxide particles in the silver matrix, thereby obtaining silver-based composite contact materials.

2. The method for preparing a silver-based composite material based on in-situ disproportionation reaction interface regulation according to claim 1, characterized in that: The silver salt is silver nitrate or silver carbonate.

3. The 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 the high-energy ball milling is: placing the raw materials into a planetary ball mill for wet ball milling, the ball milling medium is 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 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 (1), the specific process of the molten salt thermal decomposition reaction is: vacuum degree 10 -5 ~10 -3 Pa, keep warm at 200-250℃ for 4-8h, continue to heat up to 440-500℃, keep warm for 4-8h.

5. The 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 (2), the specific conditions of the hot pressing sintering are: hot pressing temperature 600~900℃, heating rate 2~10℃ / min, pressure 50~500MPa, and holding time 10~30h.

6. The 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: an extrusion ratio of 30~50:1, an extrusion temperature of 400~500℃; the process parameters of each angle rolling are specifically: a rolling deformation of 2%~20%, a rolling angle of 5°~90°, and a recrystallization annealing temperature of 350~550℃.

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

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