High-dispersity and high-compactness silver-tungsten electrical contact material and preparation method thereof

Abstract

The invention discloses a preparation method of a high-dispersity and high-compactness silver-tungsten electrical contact material, additives can be effectively dispersed through pre-coating tungsten powder and additive ball-milling pretreatment, so that the additives uniformly grow on the surface of the tungsten powder, the effect of the additives is exerted to the greatest extent, the infiltration angle of a melt to a framework is effectively improved, and the conductivity of the electrical contact material is improved. And the wettability is better. And meanwhile, the coated powder is subjected to high-energy crushing treatment, so that internal pores in the coated powder preparation process can be effectively removed, the apparent density of the powder is increased, pores serving as permeation channels in an initial pressing blank are uniform in size distribution and are communicated with one another, melt can uniformly permeate, and the effects of complete compactness and defect elimination are achieved. And after the framework is infiltrated, the fracture surface is free of holes, aggregation and reinforcement phase particle exposure, silver and tungsten are well combined, and the dispersivity and compactness of the silver-tungsten material are improved.

Description

technical field [0001] The invention relates to the technical field of electrical contact materials, in particular to a silver-tungsten electrical contact material with high dispersion and high density and a preparation method thereof. Background technique [0002] Silver tungsten contact materials have been widely used in the field of circuit breakers. On the one hand, the material contains micron-sized tungsten particles as a reinforcing phase, which can greatly improve the arc ablation resistance of contact materials; on the other hand, this material uses Powder metallurgy method, liquid phase sintering (infiltration) process, can ensure good wetting of tungsten particles and silver matrix, thereby reducing material splashing under high temperature arc, and has good resistance to arc erosion. [0003] In order to continue to improve the arc erosion resistance of silver tungsten materials, the usual practice is to use finer tungsten powder as the raw material, and at the s...

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Problems solved by technology

[0004] When the tungsten content in the silver tungsten powder is too high and the tungsten particles are too small, and the mass percentage of tungsten increases to 60%-85%, the dispersibility, processability and infiltration difficulty of the tungsten particles are greatly improved. Conventional mixed powder The additives cannot be uniformly dispersed, resulting in the infiltration of internal defects and pores that cannot be solved; in the conventional mixed powder, it is inevitable to encounter a large number of tungsten particles adjacent to the particles during the powder mixing and molding process; and due to its ultra-high Hardness, when the tungsten particles contact the surface of the particles and are pressed and formed, there will be almost no plastic deformation, so the particles cannot form mutual meshing, resulting in cracks in the compact, and even the compact cannot be formed; even if the metallographic structure of the formed product is tungsten Aggregation, silver accumulation, many internal pores and defects, and the product's anti-burning and anti-welding properties become poor

[0005] The conventional powder mixing process or conventional coating process cannot avoid the agglomeration of tungsten particles and additive particles, and cannot remove the internal pores in the coating powder preparation process, so the reinforcement phase aggregation cannot be completely eliminated when the conventional powder mixing process is used to prepare silver-tungsten contact materials; The coating process cannot avoid pores and product delamination after infiltration, as well as cross-section holes, aggregation, and exposed reinforcement phase particles, and silver and tungsten cannot form a good combination

Therefore, the production of highly dispersible silver-tungsten materials has always been a difficult problem in the industry, and this problem also limits the further improvement of the electrical breaking performance to a considerable extent.

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