Preparation And Properties Of Composite Materials Of Tungsten Copper And Dispersed Copper

The tungsten-copper composite material has the high conductivity of copper,the high melting point of tungsten,the resistance to electric corrosion,the resistance to fusion welding and the high hardness.It can be used as the material of electrical contact contacts;the dispersed phase alumina enhances the strength of the copper-based composite material It has high electrical conductivity similar to pure copper and is resistant to arc erosion.It is also currently used as an electrical contact material in the electrical and electronic field.In order to meet the needs of switching appliances for high-performance electrical contact materials,two composite materials of tungsten copper and dispersed copper(Al2O3/Cu)are prepared in this paper for use as contact materials.The work content and results are as follows:(1)Ultrafine tungsten powder is prepared through two schemes,namely ammonium tungstate direct calcination reduction method and sol-gel reduction method to prepare ultrafine tungsten powder.Study the specific preparation process of each scheme,explore various process parameters,observe the morphology of the prepared ultrafine tungsten powder,and analyze the particle size of the obtained tungsten powder.The experimental results confirm the superiority of the sol-gel method in the preparation of ultra-fine powder with good dispersibility.At the same time,in terms of sintering performance,the ultra-fine powder prepared by the sol-gel method has greater sintering activity.First,the smaller the particle size,The sintering activity is large,the second is that the particle consistency and dispersion are better than the direct calcination method.In short,the sol-gel method produces ultrafine tungsten powder with good sintering activity and uniform particle dispersion.(2)Four kinds of ultra-fine copper tungsten-copper composite powders(5WCu,10WCu,20WCu,30WCu)were prepared by sol-gel method-calcination-hydrogen reduction method,and 20WCu composite blocks were prepared by plasma activation sintering(SPS)Materials,5WCu,10WCu,20WCu,30WCu composite materials were prepared by compression molding and sintering.The results showed that:1)The density,hardness and electrical conductivity of the compression molded composite materials increased first and then decreased with the increase of sintering temperature,5WCu,10WCu,20WCu The optimal sintering temperature of 30WCu is 1060?,1090?,1090?,1120? in sequence;2)In SPS sintering,as the sintering temperature increases,the density of 20WCu composite material gradually increases close to full density,but the conductivity and hardness are The peak appears near 750?,so 750? is the best sintering temperature,and the comprehensive analysis of the optimal sintering time of 20WCu composite material is 12min.Its density,hardness and electrical conductivity are 99.61%,158.09HV,80.73%IACS,respectively.It is a tungsten-copper composite material with excellent comprehensive performance,which can be used as a high-strength and high-conductivity contact material;SPS sintered 20WCu composite material has better performance under good preparation parameters,especially in terms of hardness,the hardness of 20WCu under SPS process has been greatly improved.(3)Alumina/copper-based composite precursor was prepared by sol-gel method.After the composite precursor was decomposed under high temperature and reduced under H2 atmosphere,the mass percentage of alumina was 0.2%,0.4%,0.6%,0.8%.A kind of composite powder,which was formed by sintering alumina-copper-based composite material by powder metallurgy process of recompression and re-burning.The results showed that:1)The composite powder prepared by sol-gel method,the size of the particle reinforcement Al2O3 reached the nanometer level,in the copper-based powder Medium dispersion;2)When the molding pressure reaches 600Mpa,the density of each sintered body is the highest,and the density can be as high as 99.41%.When the initial compression molding pressure is greater than 600Mpa,the compact will crack,and 600Mpa is the optimal molding pressure;3)The plasticity of the composite material decreases with the increase of the alumina content,the hardness value increases first and then decreases,when the alumina content is 0.6wt.%,the hardness value is increased to between 150HV-160HV,and when the alumina content is continuously increased to 0.8wt.%,the Vickers hardness decreases,which is the lowest level of the four alumina reinforcement materials;4)With the alumina content Increasing conductivity gradually decreases.The one with a faster decrease in conductivity is a composite material with an alumina content of 0.8 wt.%,but the minimum value is also above 80%IACS;5)The above analysis can be obtained:the sample with the best reinforcement effect is 0.6 wt.%Al2O3/Cu-based composite material,the relative density of the material is 98.6%,the electrical conductivity reaches 94.09%IACS,the Vickers hardness is 159.73HV(hardness is 4 times that of pure copper),it is also a high strength with excellent performance High conductivity contact material,can be used in the field of switching appliances.