Surface treatment of an applied novel all-diamond microchannel heat sink for heat transfer performance enhancement

Diamond with superior thermal conductivity would effectively unlock the heat dissipation problem, while the all-diamond microchannel heat sink (AD-MCHS) is immature. In the present work, surface modification of an applied novel AD-MCHS for heat transfer enhancement associate with single-phase (deionized water) coolant was elucidated, for the first time, on an ultra-thick free-standing chemical vapor deposition (CVD) diamond plate. The heat transfer performance of as-processed and post-treated AD-MCHS by surface oxygen-introduction were systematically studied under three heat flux levels, i.e., 40 W/cm(2), 80 W/cm(2) and 120 W/cm(2), respectively. The results demonstrated that the heat transfer performance of the AD-MCHS after acid post-treatment (which was a preferable manner comparing with oxygen plasma and H2O2 bath) was prominently enhanced: 20-50% improvement of heat transfer coefficient (to the maximum of 11917 W/m(2).K), 14-28% reduction of thermal resistance and minimum thermal resistance of 0.28 degrees C/W as well as maximum temperature drop of 11.49 degrees C for heat source surface. These were the results of hydrophilic diamond surface associated with stronger surface interaction with water molecules, resulting from the reconstructed surface polar carbon-oxygen components, removal of surface graphitic phases as well as the accompanying temperate rising of surface roughness. And the heat transfer acting a more important factor would be enhanced at the expense of acceptable steadily increasing pressure drop (about 1 kPa) and negligible extra of merely < 5% with the rising of Reynolds number.