Coated SnO-coated FeOx composite oxide powder, silver-based composite electric contact material and preparation method of silver-based composite electric contact material

Abstract

The invention provides coated SnO and FeOx composite oxide powder and a silver-based composite electric contact material and a preparation method thereof, and the preparation method comprises the following steps: providing stannous mono-sulphate, dissolving, stirring to form a SnSO4 solution, and continuously reacting to obtain a solution A; adding an alkaline reaction solution into the solution A to reach a preset pH value to obtain a precursor solution; performing hydrothermal reaction on the precursor solution; washing and drying a hydrothermal reaction product to obtain SnO powder; the preparation method comprises the following steps: adding FeSO4 or FeCl2 into an aqueous solution containing SnO powder, dissolving, adding H2C2O4 to obtain a precipitate, filtering, separating, and drying; and carrying out vacuum heat treatment on the precipitate to obtain the coated SnO-coated FeOx composite oxide powder. The SnO-coated FeOx composite oxide with a controllable and adjustable valence structure can be formed, and the composite oxide is firstly applied to the field of silver-based composite electric contact, so that the Ag / SnO-coated FeOx composite electric contact material has the performance advantages of low temperature rise, long cycle life and the like in the service process.

Description

Technical Field

[0001] The present invention relates to the technical field of electric contact materials, and in particular, to a coated SnO@FeO x composite oxide powder, a silver-based composite electric contact material and a preparation method thereof. Background Art

[0002] Tin dioxide (SnO 2 ) is an important second reinforcing phase in silver-based composite electric contact materials, which is used to improve the arc erosion resistance of the silver matrix. However, during actual service, due to the poor interfacial wettability between the SnO 2 phase and the silver matrix phase, two-phase separation occurs, resulting in a decrease in the arc erosion resistance. Therefore, scholars have studied methods such as reducing the SnO 2 particle size, morphology control, doping modification (such as Fe 3+ , Cu 2+ ) to study the physical and chemical properties of SnO 2 and its interfacial wetting properties with the silver matrix, and then improve the arc erosion resistance of silver-based composite electric contact materials.

[0003] Chinese Patent Application Publication No. CN118957335A has disclosed a preparation method of a novel tin oxide-reinforced silver-based composite material with high strength and high electric erosion resistance. Starting from the concept of reinforcing phase structure design, this method obtains a tin oxide-reinforced silver-based composite material with strong interfacial bonding by introducing a trace amount of oxidant and controlling the oxidation reaction conditions, improving the mechanical properties of the silver-based composite material, and solving the problems of low strength and poor arc erosion resistance of the silver-based composite material prepared by the traditional powder metallurgy method. However, experimental studies have found that the previously developed preparation technology needs to further reduce the resistivity and temperature rise of the silver-based composite material to further improve the electric life cycle ability of the silver-based composite material. Summary of the Invention

[0004] Aiming at the defects in the prior art, the purpose of the present invention is to provide a coated SnO@FeO x composite oxide powder, a silver-based composite electric contact material and a preparation method thereof.

[0005] The present invention provides a new preparation method for coated SnO@FeO x composite oxide powder. The SnO@FeO x reinforced silver-based composite material prepared by powder metallurgy has a flat surface, a low and stable contact temperature rise, and a long cycle life during service, effectively solving the problems of uneven erosion morphology, high and unstable temperature rise in the existing Ag / SnO 2 contact materials during service, and showing excellent arc erosion resistance.

[0006] According to a first aspect of the present invention, there is provided a coated SnO@FeO x preparation method of composite oxide powder, comprising:

[0007] Providing stannous sulfate, dissolving it in deionized water, and stirring to form a SnSO 4 solution with a preset concentration and continuously reacting to obtain solution A;

[0008] Adding an alkaline reaction solution to the solution A under stirring until the pH of the solution reaches a preset pH value to obtain a precursor solution;

[0009] Introducing the precursor solution into a high-pressure reaction kettle under stirring, and placing the high-pressure reaction kettle in an incubator for hydrothermal reaction;

[0010] Washing the hydrothermal reaction product clean and drying it to obtain SnO powder;

[0011] Adding FeSO 4 or FeCl 2 to the aqueous solution containing the SnO powder, dissolving and then adding H 2 C 2 O 4 to obtain a precipitate, then filtering, separating the precipitate, and drying;

[0012] Performing vacuum heat treatment on the dried precipitate to obtain a coated SnO@FeO x composite oxide powder.

[0013] Optionally, until the pH of the solution reaches a preset pH value, wherein: the preset pH value is 7-9.

[0014] Optionally, placing the high-pressure reaction kettle in an incubator for hydrothermal reaction, wherein: the temperature of the hydrothermal reaction is 120-200 °C and the time is 8-24 h.

[0015] Optionally, performing vacuum heat treatment on the dried precipitate, wherein: the vacuum degree of the vacuum heat treatment is 10 -2 -10 -4 Pa and the temperature is 300-500 °C.

[0016] According to a second aspect of the present invention, there is provided a coated SnO@FeO x composite oxide powder, which is prepared by using the preparation method of the coated SnO@FeO x composite oxide powder described in the first aspect.

[0017] According to a third aspect of the present invention, there is provided a preparation method of a silver-based composite electrical contact material, comprising:

[0018] The coated SnO@FeO composite oxide powder prepared by the method of the first aspect or the coated SnO@FeO x composite oxide powder of the second aspect; x

[0019] The coated SnO@FeO x composite oxide powder is ball-milled and reacted with Ag powder to obtain a composite powder of Ag and SnO@FeO x ;

[0020] The composite powder of Ag and SnO@FeO x is pressed to obtain an Ag / SnO@FeO x ingot blank, and then sintered to obtain an Ag / SnO@FeO x sintered block;

[0021] The Ag / SnO@FeO x sintered block is hot-extruded to obtain an Ag / SnO@FeO x extruded wire;

[0022] The Ag / SnO@FeO x extruded wire is processed by multi-pass accumulative plastic deformation to obtain a finished wire of Ag / SnO@FeO x electrical contact material, that is, a silver-based composite electrical contact material.

[0023] Optionally, the coated SnO@FeO x composite oxide powder is ball-milled and reacted with Ag powder, wherein: the mass ratio of the Ag powder to the coated SnO@FeO x composite oxide powder is 88:(9-12);

[0024] Mix and ball-mill for 2-4 h, the ball-milling speed is 150-300 rpm, and the ball-to-material ratio is (5-10):1; FEG2000 is added as a process control dispersant during the ball-milling process.

[0025] Optionally, the sintered Ag / SnO@FeO x sintered block, wherein: the sintering temperature is 820-920 °C and the time is 4-9 h.

[0026] Optionally, the hot extrusion of the Ag / SnO@FeO x sintered block, wherein: the hydraulic pressure of the hot extrusion is 5-9 MPa and the temperature is 500-650 °C.

[0027] According to the fourth aspect of the present invention, there is provided a silver-based composite electrical contact material prepared by using the preparation method of the silver-based composite electrical contact material of the third aspect.​

[0028] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0029] 1. The preparation method of the coated SnO@FeO x composite oxide powder, through the interaction between various steps, by controlling technical parameters such as reaction temperature and reaction pressure during ingot sintering and extrusion processes, forms a SnO@FeO x composite oxide with controllable valence structure adjustment, thereby realizing wide-range adjustment of electrical properties.

[0030] 2. The present invention takes the lead in applying the coated SnO@FeO x composite oxide to the field of silver-based composite electrical contacts. The Ag / SnO@FeO x formed ingot realizes the in-situ oxidation reaction of Sn and Fe elements during the ingot sintering and extrusion processes. Utilizing the in-situ oxidation reaction mechanism of the SnO@FeO x composite oxide in the silver matrix, it improves the interfacial bonding state between the traditional SnO 2 and the Ag matrix, and improves the interfacial wettability problem between the two, enabling the Ag / SnO@FeO x composite electrical contact material to have performance advantages such as low temperature rise and long cycle life during service. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] By reading the following detailed description of the non-limiting embodiments with reference to the accompanying drawings, other features, objects, and advantages of the present invention will become more apparent:

[0032] Figure 1 is the temperature rise curve of the Ag / SnO@(75 mol.%)FeO electrical contact material in Example 3 of the present invention;

[0033] Figure 2 is the morphological characteristics of the Ag / SnO@(75 mol.%)FeO electrical contact material after erosion in Example 3 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those of ordinary skill in the art can make several modifications and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0035] The preparation method of the coated SnO@FeO x composite oxide powder provided by an embodiment of the present invention includes the following steps:

[0036] S1. Provide stannous sulfate, dissolve it in deionized water, and stir to form a SnSO 4 solution with a preset concentration and continue the reaction to obtain solution A (i.e., SnSO 4 solution);

[0037] S2. Under vigorous stirring, add the alkaline reaction solution to solution A until the pH of the solution reaches the preset pH value to obtain a precursor solution;

[0038] S3. Introduce the precursor solution into a high-pressure reactor under stirring, and place the high-pressure reactor in an incubator for hydrothermal reaction;

[0039] S4. Wash the hydrothermal reaction product thoroughly and dry it to obtain SnO powder;

[0040] S5. Add FeSO 4 or FeCl 2 to the aqueous solution containing SnO powder so that Fe 2+ can be adsorbed on the surface of the SnO powder in the solution; after dissolution, add H 2 C 2 O 4 to better form a coordination with the surface of the SnO powder, playing a role of coordination and complexation, obtaining a light yellow precipitate, then filtering, separating the precipitate, and drying;

[0041] S6. Perform vacuum heat treatment on the dried precipitate to obtain a coated SnO@FeO x composite oxide powder, where x is the stoichiometric ratio, and its value can be 2, 3 / 4, 3 / 2, etc. Its specific value is related to heat treatment conditions such as vacuum degree, sintering temperature, and time in the preparation method.

[0042]

[0043] To obtain solution A, in step S1, weigh the stannous sulfate raw material and dissolve it in deionized water; then, under vigorous stirring, form a 0.1 - 0.5 mol / L SnSO 4 solution and continue the reaction for 30 - 60 min to obtain solution A.

[0044] In some embodiments, in step S2, the magnitude of the pH value affects the precipitation reaction rate of Sn 2+ and the yield of the precipitation product. The change in pH basically has a positive correlation with the precipitation yield of Sn 2+ . The preset pH value is 7 - 9, and the alkaline reaction solution is ammonia water. Sn 2+ and OH - ions in the ammonia water of the alkaline reaction solution undergo a coprecipitation reaction to form a tin hydroxide reactant.

[0044] The temperature and time of the above hydrothermal reaction have a significant impact on the synthesis yield, microscopic morphology, and powder morphology consistency of SnO powder. In some embodiments, in step S3, a polytetrafluoroethylene-lined high-pressure reaction kettle is used, and the temperature of the hydrothermal reaction is 120-200 °C, and the time is 8-24 h. Thus, the controllable and stable preparation of the microstructure and yield of SnO powder can be achieved.

[0045] In some embodiments, in step S4, the hydrothermal reaction product obtained by the hydrothermal reaction is washed clean with deionized water and absolute ethanol, and the hydrothermal reaction product is dried at 80 °C for 5 h, and finally black SnO powder is prepared.

[0046] In some embodiments, the dosage of FeSO 4 or FeCl 2 is the same as the molar dosage of SnO powder, and the molar dosage of H 2 C 2 O 4 accounts for 3-5 mol% of the dosage of FeSO 4 or FeCl 2 .

[0047] Considering that in the initial stage of material preparation, during the drying and roasting process steps of synthesizing SnO powder, it is under vacuum or inert atmosphere protection treatment to inhibit the oxidation reaction of SnO, so as to better prepare SnO@FeO x composite oxide powder. In some embodiments, in step S6, the vacuum degree of vacuum heat treatment is 10 -2 -10 -4 Pa, and the temperature is 300-500 °C. After vacuum heat treatment, black coated SnO@FeO x composite oxide powder is obtained. In this powder material, SnO is the main phase, and FeO x coats SnO.

[0048] The preparation method of the coated SnO@FeO x composite oxide powder provided in the above embodiments of the present invention, through the interaction between each step, especially by precisely controlling the vacuum heat treatment temperature, can form a SnO@FeO x composite oxide with controllable valence structure adjustment, thereby realizing the wide-range adjustment of electrical properties.

[0049] Based on the same concept, another embodiment of the present invention provides a preparation method of a silver-based composite electrical contact material, which includes the following steps:

[0050] M1. Provide the coated SnO@FeO x composite oxide powder prepared by the above method;

[0051] M2. React the coated SnO@FeO x composite oxide powder with Ag powder by ball milling to obtain the Ag and SnO@FeO x composite powder;

[0052] M3. Press the Ag and SnO@FeO x composite powder to obtain the Ag / SnO@FeO x ingot, and then sinter it to obtain the Ag / SnO@FeO x sintered block;

[0053] M4. Hot extrude the Ag / SnO@FeO x sintered block to obtain the Ag / SnO@FeO x extruded wire; When the SnO@FeO x composite powder is mixed and pressed into an ingot with Ag powder, and then sintered and hot extruded, the Sn and Fe elements undergo an in-situ oxidation reaction in the Ag matrix;

[0054] M5. The Ag / SnO@FeO x extruded wire is processed by multi-pass accumulative plastic deformation to obtain the Ag / SnO@FeO x finished wire of the electrical contact material, that is, the silver-based composite electrical contact material, which is a coated SnO@FeO x composite oxide-reinforced silver-based composite material.

[0055] In some embodiments, in step M2, the mass ratio of the Ag powder to the coated SnO@FeO x composite oxide powder is 88:(9 - 12); the two are mixed and ball milled in a planetary ball mill for 2 - 4 h, the ball milling speed is 150 - 300 rpm, and the ball-to-material ratio is (5 - 10):1; FEG2000 is added as a process control dispersant during the ball milling process, and the Ag / SnO@FeO x composite powder is obtained after the ball milling reaction.

[0056] In some embodiments, in step M3, the prepared Ag and SnO@FeO x composite powder is loaded into a cylindrical stainless steel mold, and the pressed Ag / SnO@FeO x ingot is placed in a vacuum tube furnace, the sintering temperature is 820 - 920 °C, and the time is 4 - 9 h, so as to realize the densification sintering of the sintered block and obtain a highly densified Ag / SnO@FeO x sintered block.

[0057] To achieve the smooth extrusion of the sintered ingot, in some embodiments, in step M4, the obtained Ag / SnO@FeO xAg / SnO@FeO with a diameter of 2.3 mm was prepared by hot extrusion process under the hydraulic pressure of 5-9 MPa. x The hot extrusion temperature of the extruded wire is 500-650°C to increase the extrusion yield.

[0058] In some embodiments, in step M5, Ag / SnO@FeO x After 6 passes of cumulative plastic deformation, the extruded wire was processed to obtain Ag / SnO@FeO with a diameter of 1.85 mm. x Finished wire of electrical contact material.

[0059] For the existing Ag / SnO 2 The electrical contact composite material has problems such as uneven corrosion morphology, temperature rise and instability during service. The above embodiment of the present invention provides a coated SnO@FeO x Preparation method of composite oxide powder, thereby realizing coated SnO@FeO x The successful application of composite oxide powders in silver-based composite contact materials has made it possible to produce a new Ag / SnO@FeO x The electrical contact composite material exhibits performance advantages such as smooth surface and low and stable contact temperature rise during service, which greatly improves the material's arc erosion resistance. This method provides a reference value for the development of high-performance silver-based electrical contact composite materials.

[0060] The scheme of the present application will be explained below in conjunction with specific embodiments and comparative examples. It will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If no specific technology or conditions are indicated in the embodiments, the technology or conditions described in the literature in this area or the product specification are carried out. The reagents used or the instruments that do not indicate the manufacturer are all conventional products that can be obtained through commercial channels.

[0061] Example 1

[0062] (I) Coated SnO@FeO x Synthesis of composite oxide powders

[0063] (1-1) Weigh stannous sulfate raw material and dissolve it in deionized water; then, under vigorous stirring, form 0.1 mol / L SnSO 4 The solution continued to react for 60 min to obtain solution A;

[0064] (1-2) adding the alkaline reaction solution to solution A under vigorous stirring until the pH of the solution reaches 7, thereby obtaining a precursor solution;

[0065] (1-3) Then, the prepared precursor solution was introduced into a polytetrafluoroethylene-lined autoclave under stirring, and the autoclave was placed in an incubator at 120 °C for hydrothermal reaction for 24 h;

[0066] (1-4) The hydrothermal reaction product obtained from the reaction in step (1-3) was washed clean with deionized water and absolute ethanol, and the hydrothermal reaction product was dried at 80 °C for 5 h, and finally black SnO powder was prepared.

[0067] (1-5) A certain amount of ferrous sulfate (FeSO 4 ) was introduced into the aqueous solution containing black SnO powder, where the molar ratio of Sn to Fe was 1:1. After complete dissolution, a certain amount of oxalic acid (H 2 C 2 O 4 ) was introduced to obtain a pale yellow precipitate, which was then filtered, the precipitate was separated, and dried.

[0068] (1-6) The dried precipitate was subjected to vacuum heat treatment, with a corresponding vacuum degree of 10 -3 Pa and a heat treatment temperature of 300 °C. After vacuum heat treatment, black coated SnO@FeO composite oxide powder was obtained.

[0069] (II) Preparation of coated SnO@FeO composite oxide reinforced silver-based composite material

[0070] (2-1) Ag powder and SnO@FeO powder with a mass ratio of 88:12 were mixed and ball-milled in a planetary ball mill for 2 h, the ball-milling speed was 300 rpm, and the ball-to-material ratio was 5:1; FEG2000 was added as a process control dispersant during ball milling. After the ball-milling reaction ended, Ag and SnO@FeO composite powder was obtained;

[0071] (2-2) The Ag and SnO@FeO composite powder was loaded into a cylindrical stainless steel mold, and the pressed Ag / SnO@FeO ingot was placed in a vacuum tube furnace and continuously reaction-sintered at 820 °C for 9 h to obtain an Ag / SnO@FeO sintered block;

[0072] (2-3) The obtained Ag / SnO@FeO sintered block was processed by hot extrusion under a hydraulic pressure of 7 MPa to prepare an Ag / SnO@FeO extruded wire with a diameter of 2.3 mm, and the hot extrusion temperature was 500 °C;

[0073] (2-4) The Ag / SnO@FeO extruded wire was processed by a cumulative plastic deformation process of 6 passes to obtain an Ag / SnO@FeO electrical contact material finished wire with a diameter of 1.85 mm.

[0074] Example 2

[0075] (1) Coated SnO@Fe 3 O 4 Synthesis of Composite Oxide Powder

[0076] (1-1) Weigh the stannous sulfate raw material and dissolve it in deionized water; then, under vigorous stirring, form a 0.5 mol / L SnSO 4 solution and react for 30 min to obtain solution A;

[0077] (1-2) Add the alkaline reaction solution to solution A under vigorous stirring until the pH of the solution is 9 to obtain a precursor solution;

[0078] (1-3) Then, introduce the prepared precursor solution into a polytetrafluoroethylene-lined autoclave under stirring, and place the autoclave in an oven at 200 °C for hydrothermal reaction for 8 h;

[0079] (1-4) Wash the hydrothermal reaction product prepared in step (1-3) with deionized water and absolute ethanol, and dry the hydrothermal reaction product at 80 °C for 5 h to finally prepare black SnO powder.

[0080] (1-5) Introduce a certain amount of FeCl 2 into the aqueous solution containing black SnO powder. After fully dissolving, introduce a certain amount of oxalic acid (H 2 C 2 O 4 ) to obtain a pale yellow precipitate, then filter, separate the precipitate, and dry it.

[0081] (1-6) Perform vacuum heat treatment on the dried precipitate. The corresponding vacuum degree is 10 -3 Pa, and the heat treatment temperature is 500 °C. After vacuum heat treatment, black coated SnO@Fe 3 O 4 composite oxide powder is obtained.

[0082] (2) Preparation of Coated SnO@Fe 3 O 4 Composite Oxide Reinforced Silver Matrix Composite

[0083] (2-1) Mix and ball-mill Ag powder and SnO@Fe 3 O 4 powder with a mass ratio of 88:12 in a planetary ball mill for 4 h. The ball-milling speed is 150 rpm, and the ball-to-material ratio is 10:1; Add FEG2000 as a process control dispersant during the ball-milling process. After the ball-milling reaction, obtain Ag and SnO@Fe 3 O 4 composite powder;

[0084] (2-2) Put Ag and SnO@Fe 3 O 4 composite powder into a cylindrical stainless steel mold, and the pressed Ag / SnO@Fe 3 O 4 ingot block is placed in a vacuum tube furnace and sintered continuously at 920 °C for 4 h to obtain Ag / SnO@Fe 3 O 4 sintered block;

[0085] (2-3) The obtained Ag / SnO@Fe 3 O 4 sintered block is processed by a hot extrusion process under a hydraulic pressure of 7 MPa to prepare an Ag / SnO@Fe wire with a diameter of 2.3 mm 3 O 4 The hot extrusion temperature is 650 °C;

[0086] (2-4) The Ag / SnO@Fe 3 O 4 extruded wire is processed by a cumulative plastic deformation process of 6 passes to obtain an Ag / SnO@FeO finished wire of the electrical contact material with a diameter of 1.85 mm x

[0087] Example 3

[0088] (I) Synthesis of coated SnO@FeO x composite oxide powder

[0089] (1-1) Weigh stannous sulfate raw material and dissolve it in deionized water; then, under vigorous stirring, form a 0.1 mol / L SnSO 4 solution and react for 60 min to obtain solution A;

[0090] (1-2) Add the alkaline reaction solution to solution A under vigorous stirring until the pH of the solution is 7 to obtain a precursor solution;

[0091] (1-3) Then, introduce the prepared precursor solution into a polytetrafluoroethylene-lined high-pressure reaction kettle under stirring, and place the reaction kettle in a constant temperature oven at 120 °C for hydrothermal reaction for 24 h;

[0092] (1-4) Wash the hydrothermal reaction product prepared in step (1-3) with deionized water and absolute ethanol, and dry the hydrothermal reaction product at 80 °C for 5 h to finally prepare black SnO powder.

[0093] (1-5) Introduce a certain amount of ferrous sulfate (FeSO 4), where the molar ratio of Sn to Fe is 1:3. After complete dissolution, a certain amount of oxalic acid (H 2 C 2 O 4 ) is introduced to obtain a pale yellow precipitate, which is then filtered, separated, and dried.

[0094] (1-6) The dried precipitate is subjected to vacuum heat treatment at a corresponding vacuum degree of 10 -3 Pa and a heat treatment temperature of 300 °C to obtain black coated SnO@(75 mol.%) FeO composite oxide powder.

[0095] (II) Preparation of coated SnO@(75 mol.%) FeO composite oxide reinforced silver-based composite

[0096] (2-1) Ag powder and SnO@(75 mol.%) FeO powder with a mass ratio of 88:12 are mixed and ball-milled in a planetary ball mill for 2 h at a ball-milling speed of 300 rpm and a ball-to-material ratio of 5:1. FEG2000 is added as a process control dispersant during ball milling. After the ball-milling reaction, SnO@(75 mol.%) FeO composite powder is obtained;

[0097] (2-2) The Ag and SnO@(75 mol.%) FeO composite powder is loaded into a cylindrical stainless steel mold. The pressed Ag / SnO@(75 mol.%) FeO ingot is placed in a vacuum tube furnace and continuously reaction-sintered at 820 °C for 9 h to obtain an Ag / SnO@(75 mol.%) FeO sintered block;

[0098] (2-3) The obtained Ag / SnO@(75 mol.%) FeO sintered block is processed by hot extrusion under a hydraulic pressure of 7 MPa to prepare an Ag / SnO@(75 mol.%) FeO extruded wire with a diameter of 2.3 mm at a hot extrusion temperature of 500 °C;

[0099] (2-4) The Ag / SnO@(75 mol.%) FeO extruded wire is processed by a cumulative plastic deformation process of 6 passes to obtain a finished Ag / SnO@(75 mol.%) FeO electrical contact material wire with a diameter of 1.85 mm.

[0100] Example 4

[0101] (I) Synthesis of coated SnO@FeO x composite oxide powder

[0102] (1-1) Weigh stannous sulfate raw material and dissolve it in deionized water. Then, under vigorous stirring, a 0.1 mol / L SnSO 4The solution was continuously reacted for 60 min to obtain solution A;

[0103] (1-2) The alkaline reaction solution was added to solution A under vigorous stirring until the pH of the solution reached 7 to obtain a precursor solution;

[0104] (1-3) Then, the prepared precursor solution was introduced into a polytetrafluoroethylene-lined autoclave under stirring, and the autoclave was placed in an incubator at 120 °C for hydrothermal reaction for 24 h;

[0105] (1-4) The hydrothermal reaction product prepared in step (1-3) was washed clean with deionized water and absolute ethanol, and the hydrothermal reaction product was dried at 80 °C for 5 h to finally prepare black SnO powder.

[0106] (1-5) A certain amount of ferrous sulfate (FeSO 4 ) was introduced into the aqueous solution containing black SnO powder, where the molar ratio of Sn to Fe was 1:5. After complete dissolution, a certain amount of oxalic acid (H 2 C 2 O 4 ) was introduced to obtain a pale yellow precipitate, which was then filtered, and the precipitate was separated and dried.

[0107] (1-6) The dried precipitate was subjected to vacuum heat treatment, with a corresponding vacuum degree of 10 -3 Pa and a heat treatment temperature of 300 °C. After vacuum heat treatment, black coated SnO@(83 mol.%) FeO composite oxide powder was obtained.

[0108] (II) Preparation of coated SnO@(83 mol.%) FeO composite oxide reinforced silver-based composite

[0109] (2-1) Ag powder and SnO@(83 mol.%) FeO powder with a mass ratio of 88:12 were mixed and ball-milled in a planetary ball mill for 2 h, with a ball-milling speed of 300 rpm and a ball-to-material ratio of 5:1; FEG2000 was added as a process control dispersant during the ball-milling process. After the ball-milling reaction ended, Ag and SnO@(83 mol.%) FeO composite powder was obtained;

[0110] (2-2) The Ag and SnO@(83 mol.%) FeO composite powder was loaded into a cylindrical stainless steel mold, and the pressed Ag / SnO@(83 mol.%) FeO ingot was placed in a vacuum tube furnace and continuously reacted and sintered at 820 °C for 9 h to obtain an Ag / SnO@(83 mol.%) FeO sintered block;

[0111] (2-3) The obtained Ag / SnO@(83 mol.%)FeO sintered mass is used to prepare Ag / SnO@(83 mol.%)FeO extruded wire with a diameter of 2.3 mm through a hot extrusion process under a hydraulic pressure of 7 MPa, and the hot extrusion temperature is 500 °C;

[0112] (2-4) The Ag / SnO@(83 mol.%)FeO extruded wire is processed through a cumulative plastic deformation process of 6 passes to obtain the finished Ag / SnO@(83 mol.%)FeO electrical contact material wire with a diameter of 1.85 mm.

[0113] In addition, in the comparative example, the reinforcing phase oxide powder is changed for comparison at the same level, that is, according to the same preparation process route as the above-mentioned examples, the difference is only that the coated SnO@FeO x composite oxide powder in step (2-1) is respectively replaced with SnO 2 , FeO, Fe 3 O 4， to respectively prepare the finished Ag / SnO 2 and Ag / FeO, Ag / Fe 3 O 4 electrical contact material wires. As comparative samples, the comparative samples and the samples in the above-mentioned Examples 1-4 are respectively subjected to electrical performance test and evaluation, and the results are shown in Table 1.

[0114] Table 1 Characterization results of electrical properties, temperature rise and cycle life of each sample

[0115] Sample Resistivity / μΩ·cm Temperature Rise / K Cycle Life / times Example 1 2.34 53.9 84024 Example 2 2.32 54.8 72935 Example 3 2.26 55.9 92802 Example 4 2.35 54.9 82947 <![CDATA[Ag / SnO 2 > 2.36 53.7 52984 Ag / FeO 2.43 54.7 42984 <![CDATA[Ag / Fe 3 O 4 > 2.54 59.3 32984

[0116] According to the results in Table 1, it can be seen that compared with Ag / SnO 2 and Ag / FeO, Ag / Fe 3 O 4 electrical contact materials, the samples in Examples 1-4 of the present invention all show lower resistivity, lower contact temperature rise and longer service life performance. In particular, the SnO@(75 mol.%)FeO reinforcing phase powder developed in Example 3 is used as the second reinforcing phase, and the Ag / SnO@(75 mol.%)FeO electrical contact material prepared has the best comprehensive performance, and the corresponding temperature rise curve and erosion characteristics at the end of the cycle 92802 life are as Figure 1 and Figure 2 shown. Therefore, the coated SnO@FeO x composite oxide reinforced silver-based composite electrical contact material prepared in the above-mentioned examples of the present invention is expected to solve the problems of high temperature rise and short life of traditional Ag / SnO 2 electrical contact materials.

[0117] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various deformations or modifications within the scope of the claims, which do not affect the essence of the present invention. The above preferred features can be used in any combination without conflict.

Claims

1. A coated SnO@FeO x A method for preparing a composite oxide powder, characterized in that: include: Provide stannous sulfate, dissolve it in deionized water, stir to form a SnSO4 solution of a preset concentration and continue to react to obtain solution A; Adding the alkaline reaction solution to the solution A under stirring until the pH of the solution reaches a preset pH value to obtain a precursor solution; Introducing the precursor solution into a high-pressure reactor under stirring, and placing the high-pressure reactor in a thermostat for hydrothermal reaction; The hydrothermal reaction product is washed and dried to obtain SnO powder; Add FeSO4 or FeCl2 to the aqueous solution containing the SnO powder, add H2C2O4 after dissolving to obtain a precipitate, then filter, separate the precipitate, and dry it; The dried precipitate was subjected to vacuum heat treatment to obtain coated SnO@FeO x Composite oxide powder.

2. The coated SnO@FeO according to claim 1 x A method for preparing a composite oxide powder, characterized in that: The step of heating the solution until the pH value of the solution reaches a preset pH value, wherein the preset pH value is 7-9.

3. The coated SnO@FeO according to claim 1 x A method for preparing a composite oxide powder, characterized in that: The high-pressure reactor is placed in a thermostat for hydrothermal reaction, wherein the temperature of the hydrothermal reaction is 120-200° C. and the time is 8-24 hours.

4. The coated SnO@FeO according to claim 1 x A method for preparing a composite oxide powder, characterized in that: The dried precipitate is subjected to vacuum heat treatment, wherein the vacuum degree of the vacuum heat treatment is 10 -2 ~10 -4 Pa, temperature is 300~500℃.

5. A coated SnO@FeO x The composite oxide powder is characterized by: Using the coated SnO@FeO according to any one of claims 1 to 4 x The composite oxide powder is prepared by a preparation method.

6. A method for preparing a silver-based composite electrical contact material, characterized in that: include: Provided is a coated SnO@FeO prepared by the method described in any one of claims 1 to 4 x Composite oxide powder, or the coated SnO@FeO according to claim 5 x Composite oxide powder; The coated SnO@FeO x The composite oxide powder and Ag powder were ball-milled to obtain Ag and SnO@FeO x Composite powder; Pressing the Ag and SnO@FeO x Composite powder to obtain Ag / SnO@FeO x Press the ingot and then sinter to get Ag / SnO@FeO x Sintered blocks; Hot extrusion of the Ag / SnO@FeO x Sintered blocks to obtain Ag / SnO@FeO x Extruded wire; The Ag / SnO@FeO x The extruded wire is processed by multiple cumulative plastic deformation processes to obtain Ag / SnO@FeO x The finished wire material of the electric contact material is a silver-based composite electric contact material.

7. The method for preparing the silver-based composite electrical contact material according to claim 6, characterized in that: The coated SnO@FeO x The composite oxide powder and the Ag powder are subjected to ball milling reaction, wherein: the Ag powder and the coated SnO@FeO x The mass ratio of the composite oxide powder is 88:(9-12); The mixture was ball-milled for 2 to 4 hours at a ball-milling speed of 150 to 300 rpm and a ball-to-material ratio of (5 to 10):

1. FEG2000 was added during the ball-milling process as a process control dispersant.

8. The method for preparing the silver-based composite electrical contact material according to claim 6, characterized in that: The sintering process obtains Ag / SnO@FeO x Sintered block, wherein: the sintering temperature is 820-920°C, and the time is 4-9h.

9. The method for preparing the silver-based composite electrical contact material according to claim 6, characterized in that: The hot extrusion Ag / SnO@FeO x Sintered block, wherein: the hydraulic pressure of hot extrusion is 5-9MPa, and the temperature is 500-650℃.

10. A silver-based composite electrical contact material, characterized in that: The silver-based composite electrical contact material is prepared by the preparation method of any one of claims 6 to 9.

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