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CN-117535547-B - High-strength high-conductivity silver tungsten carbide nickel graphite electrical contact material and preparation method thereof

CN117535547BCN 117535547 BCN117535547 BCN 117535547BCN-117535547-B

Abstract

The invention belongs to the field of preparation of electrical contact materials, and in particular relates to a high-strength high-conductivity silver tungsten carbide nickel graphite electrical contact material and a preparation method thereof, wherein the method comprises the following steps of S1, presintering nickel-coated graphite powder by adopting reducing gas or inert gas protection, and sieving; S2, mixing the screened nickel-coated graphite powder, silver powder and tungsten carbide powder, S3, granulating the mixed powder by a wet method, and then performing primary compression molding, presintering and infiltration to obtain the silver-tungsten-nickel carbide graphite electric contact material with high strength and high conductivity. Compared with the traditional silver tungsten carbide graphite material, the invention solves the problem that the graphite-containing material cannot be infiltrated with silver, adopts an infiltration process to ensure that the material has higher strength and better conductivity, and simultaneously ensures that the material has good fusion welding resistance by adding graphite powder.

Inventors

  • FEI JIAXIANG
  • YU XIUQING
  • KONG XIN
  • GUO RENJIE
  • HE ZHENGHAI
  • WAN DAI
  • SONG LINYUN
  • BAI XIAOPING
  • WEI QINGHONG

Assignees

  • 浙江福达合金材料科技有限公司

Dates

Publication Date
20260508
Application Date
20231106

Claims (6)

  1. 1. The preparation method of the high-strength high-conductivity silver tungsten carbide nickel graphite electrical contact material is characterized by comprising the following steps of: s1, presintering nickel-coated graphite powder by adopting reducing gas or inert gas protection, and screening; S2, mixing the screened nickel-coated graphite powder with silver powder and tungsten carbide powder; s3, granulating the mixed powder by adopting a wet method, and then performing primary compression molding, presintering and infiltration to obtain the silver tungsten carbide nickel graphite electrical contact material with high strength and high conductivity; in the step S1, the adopted nickel-coated graphite powder is nickel-coated graphite powder with granularity below 200 meshes, which is obtained by a chemical coating process, wherein the mass percentage of nickel is 50% -90%; in the step S1, the presintering temperature is 200-600 ℃ and the presintering time is 1-6 h; The high-strength high-conductivity silver tungsten carbide nickel graphite electrical contact material comprises, 50-75 Parts of Ag; 25-50 parts by mass of WC; ni 1-15 parts by mass; c0.4-3 parts by mass.
  2. 2. The method of claim 1, wherein in step S1, the powder is sieved through a 150-250 mesh sieve.
  3. 3. The method of claim 1, wherein in step S2, the screened nickel-coated graphite powder, tungsten carbide powder and silver powder are mechanically mixed together for 2-6 h.
  4. 4. The method of claim 1, wherein in step S3, the presintering is performed under the protection of hydrogen or ammonia decomposition gas at 400-950 ℃ for 1-4 h.
  5. 5. The method of claim 1, wherein in the step S3, the infiltration is performed by adopting hydrogen or ammonia decomposition gas, the temperature is 1000-1300 ℃ and the time is 1-4 h, the infiltration sheet adopts silver sheets or fine-grain silver sheets, and the nickel content in the fine-grain silver sheets is 0-0.3%.
  6. 6. A silver tungsten carbide nickel graphite electrical contact material obtained by the method of any one of claims 1-5.

Description

High-strength high-conductivity silver tungsten carbide nickel graphite electrical contact material and preparation method thereof Technical Field The invention belongs to the field of preparation of electrical contact materials, and particularly relates to a high-strength high-conductivity silver-carbide tungsten-nickel-graphite electrical contact material and a preparation method thereof. Background The circuit breaker is mainly used for switching on and off a load circuit and switching off a fault circuit, ensures safe operation and is an important protection electric appliance in a low-voltage distribution network. As is known, the "heart" of a circuit breaker is an electrical contact that is capable of breaking both extremely high short-circuit currents and of switching on and off rated currents infrequently. In order to meet the use requirement of a circuit breaker, the circuit breaker is generally composed of a moving contact and a fixed contact in a paired manner, wherein the moving contact is required to have the characteristic of strong arc erosion resistance, agW or AgWC materials produced by a powder metallurgy infiltration process are generally adopted, and the fixed contact is required to have the characteristics of good fusion welding resistance and certain arc erosion resistance, and AgC materials produced by AgWCC or extrusion processes produced by a powder metallurgy sintering process are generally adopted. Most of these materials are used in ac circuit breakers. With the rapid development of new energy industries such as wind power generation, electric automobiles and the like, the demand for high-voltage direct current breakers is increasing, and because direct current has no characteristic of periodic zero crossing of alternating current, the arc is more difficult to extinguish, so the requirement on the arc erosion resistance of a static contact is high. When the static contact AgWCC or AgC material commonly used in the original alternating current circuit breaker is used for the direct current circuit breaker, although the fusion welding resistance meets the requirements, the arc erosion resistance is poor, and the electric life often cannot meet the requirements. In summary, agWCC materials provided by the preparation method in the prior art have the following problems that 1. In the process of switching on and breaking rated current of a high-voltage direct-current circuit breaker, an arc is more difficult to extinguish, and a static contact prepared by adopting AgWCC materials is insufficient in arc erosion resistance, so that the problem of insufficient electric life is caused, and 2. AgWCC materials cannot be produced by adopting an infiltration process due to poor wettability of graphite and liquid silver. Disclosure of Invention The invention aims to overcome the defects and the shortcomings of the prior art and provide a high-strength high-conductivity silver-carbide tungsten-nickel-graphite electric contact material and a preparation method thereof. The technical scheme adopted by the invention is that the preparation method of the high-strength high-conductivity silver-carbide tungsten-nickel-graphite electric contact material comprises the following steps: s1, presintering nickel-coated graphite powder by adopting reducing gas or inert gas protection, and screening; S2, mixing the screened nickel-coated graphite powder with silver powder and tungsten carbide powder; S3, granulating the mixed powder by adopting a wet method, and then performing primary compression molding, presintering and infiltration to obtain the silver tungsten carbide nickel graphite electrical contact material with high strength and high conductivity. Preferably, in the step S1, the nickel-coated graphite powder is nickel-coated graphite powder with granularity below 200 meshes obtained through a chemical coating process, wherein the mass percentage of nickel is 50% -90%. Preferably, in step S1, the pre-sintering temperature is 200-600 ℃ and the pre-sintering time is 1-6 h. Preferably, in the step S1, screening is carried out by screening with a 150-250 mesh sieve, and taking undersize powder. Preferably, in the step S2, the nickel-coated graphite powder, the tungsten carbide powder and the silver powder after sieving are mechanically mixed together for 2-6 hours. Preferably, in the step S3, the presintering is carried out by adopting hydrogen or ammonia decomposition gas for protection, the temperature is 400-950 ℃ and the time is 1-4 h. Preferably, in the step S3, the infiltration adopts hydrogen or ammonia decomposition gas for protection, the temperature is 1000-1300 ℃ and the time is 1-4 hours, and the infiltration sheets adopt silver sheets or fine-grain silver sheets, wherein the nickel content in the fine-grain silver sheets is 0-0.3%. A silver tungsten carbide nickel graphite electrical contact material, which is obtained by adopting the preparation method. Preferably, the silver tungsten carb