Study On Arc Ablation Properties Of W-Cu Composite Electric Contact Materials

In this paper,W-Cu composite powders were prepared by electroless copper plating.The effects of different temperature,formaldehyde concentration and sodium hydroxide concentration on the microstructure of powders were studied.W-Cu composites with different mass ratios of W80Cu20,W70Cu30 and W60Cu40 were prepared by hot pressing sintering method,and their physical and mechanical properties were tested.The arc ablation resistance of W-Cu composites with different compositions,discharge times and voltages was studied by using arc ablation device,and the ablation mechanism was analyzed.In the experiment of electroless copper plating,the results show that the concentration of formaldehyde 20 m L /L,the temperature of 60 ?,the concentration of sodium hydroxide 14 g/L are suitable for the electroless copper plating experiment,and the coating is complete.Then the powder was sintered at 1050 ? by hot pressing sintering technology.The density,electrical conductivity and thermal conductivity showed a decreasing trend,while the hardness and bending strength showed an increasing trend with the increase of the proportion of W component.The ablation voltage was set at 8 k V,and the ablation experiment of W-Cu composites with three components was carried out.The process of arc initiation to annihilation was recorded by high-speed camera.The results show that with the increase of W content,the breakdown current and breakdown strength of the three materials have little change.The composite material of W70Cu30 has a short arc burning time,discharge distance and a small arc energy.The observation of the ablation area shows the ablation area presents a "crater" shape.We selected W70Cu30 composite material for ablation experiments with different discharge times,and the ablation voltage was set at 8 k V.It is found that the breakdown current,arc energy and arc burning time remain basically the same,the breakdown intensity decreases slowly with the increase of the discharge times,and the discharge distance increases slowly with the increase of the discharge times.With the increase of ablation times,the ablation area increases.The damage degree of the sample also gradually increases,and cracks form in the heat-affected area under the action of thermal stress.W70Cu30 composites were selected for ablation tests under different voltages,and ablation voltages were set as 2,4,6,8 k V.It is found that with the increase of voltage,the breakdown current,the discharge distance and the arcing time increases,the breakdown intensity decreases.By observing the morphology of ablation area,it is found that with the increase of voltage,the ablation area,and the height of surface bulge increases.Raman spectra showed that CuO was formed on the surface of the material after ablation,and no oxidation state of W was detected.