Preparation And Properties Of Ultrafine Crystalline W-Cu Contact Materials

W-Cu contact materials have been used in vacuum contactors，oil and SF6interrupters,transformer switch due to high arc erosion, electrical erosion resistance and dielectricstrength. With the rapid development of modern industry, there are higher requirement onfabrication technology and performance of W-Cu contact materials. In this paper ultrafinecrystalline W-Cu contact materials were fabricated by combining mechanical alloyingtechnique (MA) and spark plasma sintering (SPS). And the technology parameters andperformance of W-Cu contact materials were investigated and analyzed.Nanocrystalline W-Cu composite powder with different contents were fabricated bymechanical alloying (MA). The effect of milling time on the phase components, crystallitesize, microstrain and morphology of the composites were investigated. The results showthat crystallite size and lattice parameter of W-Cu powder are decreased with increasingmilling time, whereas the mircostrain is increased at the early stage of milling and thendeclined slightly and stabilized; the solid solubility of Cu dissolved in W is largelyextended and the main factor is dynamics driver; the structure of W-Cu composite powderchanged a lot with prolonging milling time, at the early stage of milling the compositepowder are fragmented, result in the formation of laminar structure, with increasing millingtime and due to continuous fracturing, the laminar structure is refined and the homogenousspherical particle is formed.Spark plasma sintering was used to consolidate MA nanocrystalline W-Cu powders tobulk compacts. The effect of Cu content, milling time, sintering temperature and ballingparameters on the microstructure and properties of the composites were studied. The resultsshow that the increasing of Cu content is beneficial to depressing the trend of congregatinggrain growth, and the density, electrical conductivity are remarkable increased. Thehardness of the sintered compacts is gradually decreased as Cu content increased. Withprolonging the milling time, the structure W particle is become to laminar, the density andhardness are increased while electrical conductivity is decreased. With an increase of the sintering temperature from800℃to950℃, the relative density, hardness and electricalconductivity of the prepared composites are also increased, but the crystallite size is littlechanged. The homogeneous structure and higher hardness can be got when under betterballing technology, but the density and electrical conductivity are declined slightly.MA-SPS technology is an effective method to synthesize W-Cu contact material withnear full dense, homogeneous microstructure and high performance in a short time and lowtemperature. So, MA-SPS technology is an alternatively promising method to fabricateultrafine crystalline W-Cu contact material.