Of Wc Preparation And Properties Of Dispersion Strengthened Copper

Dispersion strengthened copper (DSC) is widely used in automobile and electronic industry because of its excellent conductivity and high-temperature property. Present work is an attempt to develop a new kind of DSC.WC/Cu composite powders with different WC content milled for a different time were examined with SEM and XRD technique to find out the optimum milling time in terms of morphology, mean powder size and phase composition. On the basis of the result, composite powders were prepared and compacted by cold isostatic press (CIP). Compacted samples were sintered under different conditions to investigate the effect of processing parameters on materials properties (density, hardness, tensile stress and conductivity) after sintering.As a result, composite powders with uniform particle distribution and refined microstructure could be prepared by means of high energy milling, and prolonged milling time resulted in smaller powder size. Powder containing more WC particles refined faster than that with a low content. 24h' milling seemed better overall. No phase transformation occurred during milling. Milling caused lattice strain of copper powders.Driving force for sintering were powder surface energy and stored energy caused by deformation. Sintering was affected by particles content, sintering temperature and preserving time. Generally, more particles content, higher sintering temperature and longer time led to a more complete sintering and improved microstructure. Optimum sintering differed depending on particle content, and for Cu-4%WC the best sintering was at 1000℃ for 2.5h. In material with a high WC content many pores and particle agglomerations were observed.Under the same compaction pressure, green density of sample with a low WC content was higher than that with a high content. Sintering could improve density slightly. Properties of material were determined mainly by the microstructure. The higher the density was, the more completely the sintering progressed, the more uniform the microstructure was, the better properties the material exhibited. Increase in particle content, porosity and solved impurity resulted in decreased electrical conductivity. But the effect that particle content and porosity had on the conductivity was much minor compared with the impurity. Comparison between all materials showed Cu-4%WC sintered at 1000@ for 2.5h had the best overall properties. No obvious recrystallization was observed in materials deformed at high temperatures.