الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Tungsten- copper (W–Cu) electrodes have been used widely to machine die steel and tungsten carbide workpieces owing to the high thermal conductivity of Cu, and the better spark erosion resistance, low thermal expansion coefficient and high melting temperature of W. In this research, W-Cu composites containing 20%, 25%, and 30wt.% Cu were produced by powder metallurgy technique using wet mixtures of elemental powders. Cold compaction was carried out under pressures from 300 to1200MPa, while sintering was achieved in vacuum at 1400 ºC for 1hr, and 2hr. The particle size and shape of powders, as well as the microstructures after wet mixing, compaction, and sintering were investigated by using SEM. The results show that, wet mixed powders were proved to be homogeneous, and the copper flake particles were semi-coated by fine spherical tungsten particles. The relative green density and sintered density were found to increase with increasing compaction pressure and copper content. After sintering, the composite revealed homogeneous structure. The relative sintered density was found to increase with sintering time. Tungsten- copper composite compacted under 1200 MPa and sintered at 1400ºC for 2hr exhibited the highest relative sintered density, hardness, and compressive strength. Also, it exhibited the lowest electrical resistivity and coefficient of thermal expansion. W-Cu electrodes including 20, 25, and 30wt.%Cu, were used with K110 tool steel work piece for EDM machining. The results show that, increasing Cu content increases Metal Removal Rate (MRR), Electrode Wear Rate (EWR), and decrease Surface Roughness (SR)