Manufacture And Properties Of Nanodiamond/Cu Composites By Powder Metallurgy

Duo to the excellent mechanical properties, good wear resistance, high electrical and thermal conductivity, copper matrix composites are widely applied in electronic packaging, electrical brushes, electrical contacts and resistance welding electrodes. Seeking new strengthening particulates which have both high conductivity and high mechanical properties is significant for the study and application of copper matrix composites. Nanodiamond (ND) possesses many superior properties, such as superhigh hardness, high wear resistance, excellent thermal conductivity as well as low coefficient of thermal expansion (CTE). It is strongly expected that superior copper matrix composites will be attained by dispersing ND into the copper matrix homogeneously.The ND/Cu composites were fabricated by using powder metallurgy method. The effect of ball-milling parameters, pressure, sintering temperature and time on the microstructures and properties of composites was investigated to determine the optimized processing parameters. The electrical conductivity, tensile strength, wear resistance and other properties of ND/Cu, Microdiamond (MD)/Cu, Annealed- Nanodiamond (AND)/Cu composites were tested, and the microstructures of the composites were analyzed by SEM and TEM. The results showed that the electrical conductivity of ND/Cu composites was gradually decreased with increasing ND content, while its hardness and friction and wear resistance was evidently improved, and the tensile strength was increased at first then decreased. The soft resistance temperature of ND/Cu composites was above 600℃. The ND was homogeneously dispersed in the copper matrix and the composites were compacted with the ND content less than 1%.With increasing MD content, the properties of the MD/Cu composites were similar to ND/Cu composites. The electrical conductivity of MD/Cu composites was higher than ND/Cu composites with the same diamond content, while the hardness and wear resistance were lower compared to the ND/Cu composites. A composite nanostructure with graphite as the shell and nanodiamond as the core was gained after the ND annealed at 1100℃for 60min. The AND was much more homogeneously dispersed in the copper matrix resulting from alleviate the agglomerates of ND. Therefore, the properties such as electrical conductivity, tensile strength, wear resistance of AND/Cu composites were superior to ND/Cu composites.