Study of process parameters in conventional powder metallurgy of silver

Abstract

Compaction, sintering and physical properties of silver powder were investigated. The silver powder was uniaxially compacted into a cylindrical specimen using compaction pressures of 13.79, 27.58, 41.37 and 55.16 MPa. Compacted parts were sintered at 700, 800 and 900°C in argon atmospheres. In addition, compacted parts were also sintered in vacuum at 900°C. For the sintering temperatures of 700 and 800°C, it was found that the sintered density increased as the compaction pressure increased below 40 MPa, while the sintered density decreased at a compaction pressure above 40 MPa. At the sintering temperature of 900°C, the sintered density decreased with increasing compaction pressure. The highest sintered density of 10.22 g⋅cm-3 (67.41 % relative density) was obtained at a temperature of 900°C under argon atmosphere for compaction pressure of 13.79 MPa. At this sintering temperature, vacuum sintering gave a slightly higher sintered density than argon atmosphere. Moreover, the difference in shrinkage of thickness and diameter of the sintered parts was observed. The diameter has higher shrinkage than the thickness. The weight of the specimen did not affect the sintered density, whereas the compaction pressure, sintering temperature and atmosphere influenced the sintered density.