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 degrees C with a heating rate of 5 degrees C/min under argon. The annealed powders were then consolidated at sintering temperatures of 600 degrees C, 650 degrees C and 700 degrees 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 degrees C, 650 degrees C and 700 degrees C respectively. The Vickers hardness values were 132 GPa, 132 GPa and 1.13 GPa. An average grain size of about 0.5 mu m was obtained in sample sintered at 600 degrees C and 650 degrees 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 degrees C. Thermal conductivity remained relatively high for all the sintered samples. (C) 2014 Elsevier B.V. All rights reserved.