Optimization of sintering parameters for diamond-copper composites in conventional sintering and their thermal conductivity

The diamond-copper composite system has become the most attractive material in the research and development of new materials for thermal management applications. In this work, copper matrix composites reinforced with diamond particles were produced by conventional sintering method through powder metallurgy route. Diamond particles were used as uncoated, copper(nickel) coated (CuD) and chromium coated (CrD). Diamond particles were mixed with copper powder mechanically and cold compacted under uniaxial conditions. The cold compacted pellets were sintered in a vacuum tube furnace. Cold compaction pressure, sintering temperature and holding time were optimized for maximum densification and the composites were produced with different volume percent of diamond particles at optimized parameters. The densification was found maximum for the composite samples cold compacted at 525 MPa and sintered at 900 °C for 2 h. The best thermal conductivities achieved with uncoated, CuD and CrD particles were 275, 284 and 312 W/mK respectively. In comparison, better densification and good interfacial bond with copper matrix was observed in the CrD reinforced composites.