Effect of SPS consolidation parameters on submicron Cu and Cu–CNT composites for thermal management

The effect of oxygen content on sub-micron sized copper and copper reinforced with CNTs was investigated using spark plasma sintering (SPS). The powders were initially annealed for 30 min at 550 °C with a heating rate of 5 °C/min under argon. The annealed powders were then consolidated at sintering temperatures of 600 °C, 650 °C and 700 °C with a constant pressure of 50 MPa and a holding time of 5 min. The density, phase composition, microstructure, Raman spectra, hardness and thermal conductivity of the resulting materials were measured. The oxygen content of pure Cu powder after heat treatment reduced from 0.54 wt.% to 0.05 wt.%. A relative density of 98.70%, 99.20% and 96.27% was obtained at 600 °C, 650 °C and 700 °C respectively. The Vickers hardness values were 1.32 GPa, 1.32 GPa and 1.13 GPa. An average grain size of about 0.5 μm was obtained in sample sintered at 600 °C and 650 °C. The Raman spectra of the composite samples showed that the consolidation condition did not damage the CNTs during sintering. The thermal conductivity of 395 ± 20 W/m-K was measured for the pure copper sintered at 600 °C. Thermal conductivity remained relatively high for all the sintered samples.