Research On Influence Of Milling Techniques On Tungsten-copper Composite Powder And Its Alloy

The well combination of copper of preeminent conductivity and Tungsten of high-temperature strength and arc-resistant leads a serial of preeminent properties. Tungsten-copper materials are usually made electric contracts, electronic seal, thermal materials. Because Tungsten and copper do not dissolve each other, the preparation methods of W-Cu composite material prove particular. And as nano-particles manifest some unusual properties and intensive activity, the preparation methods of nano-Tungsten-copper composite material is more particular.The thesis adopts powder-mixing, milling, pressing, sintering to prepare Tungsten-copper composite materials.The nano-tungsten-copper powders were prepared by high-energy ball milling. The influence of different times of ball milling and transform direction on the granularity, structure and composing of nano-tungsten-copper composite powders were studied.The aim of experiment is to confirm the proper technical route.The influence of techniques parameter such as powder granularity, the uniformity of grain diameter, pressure, sintering temperature,the heat preservation time on the capability of composites.And expect gaining the nano-W-15Cu composites with very minute grain microstructure and excellent uniformity.By the research on preparation of nano-tungsten-copper composite powders using the high-energy ball milling, the thesis discoveries: The nano-crystalline W-Cu composite powders that is the dimension of grain is to be nanon and the distribution is symmetrical were prepared by high-energy ball milling.Along with the rise of milling time,the granularity of tungsten-copper composite powders reduce gradually.The granularity of composite powders which the milling time is 60 hour is the most minute and the distribution is also the most uniformity.By the research on the formation of nano-Tungsten-copper composite material, the thesis discoveries: The effect of powder property upon the performance of sintered body is great. They advantages sintering which are smaller size, more regular appearance and better plasticity. The samples get initiative densification when sintering-temperature is upon 900°C. But the densities will have a wider increase when sintering-temperature rise up to 1000°C. So the sample's density is increasing with the rise of temperature. But the temperature has little effect on the density when temperature rise up to 1350°C. When the milling time is 10 hours,20 hours,40 hours and 60 hours respectively, force and sinter inl350°C with the protection of the Ar.After the powders which the milling time is 60hour is sintered inl350°C,the relative density of sample were measured is 98.8% that is the most high. The microstructure after sintering were observed show that copper distribute the interface of tungsten crystal symmetrically.The dimension of tungsten grain is 1～2μm.The study show that minish the granularity of powders can make the sinter capability improve and can also make the sinter densities improve. The best sinter technique is that the proportion of ball and material is 5:1,the milling time is 60 hours, the transform direction time is 30 minutes, the rotate speed is 150 r/min without lubricant,the pressure is 25MPa without heating, the pressure is 25MPa with heating, the temperature of heat preservation is 1350°C,the times of heat preservation is 6 hours.