Fabrication and capillary performance of multi-scale microgroove ceramic wicks via nanosecond laser irradiation for ultrathin ceramic heat pipes

Abstract

Ultrathin ceramic heat pipes have great potential in solving the heat dissipation problems for power semiconductor devices with ever-increasing power density. Ceramic wick structures with superior capillary performance plays a decisive role in the heat transfer performance of the ceramic heat pipe. In the study, a multi-scale microgroove wick (MSMGW) prepared by laser irradiation is developed. The effects of laser scan pitch, laser fabrication parameters and ceramic material on the surface morphology, wettability and capillary performance of the MSMGW were investigated. The 66 μm thick ceramic wick proposed that consists of micron-sized microgrooves, nanoscale voids and material surface reconsolidation layers demonstrates remarkable capillary performance. The laser scan pitch, laser power, repetition frequency, and scanning speed have significant impacts on the surface morphology and capillary performance of MSMGW. The MSMGW with optimal parameters could reach capillary wicking height of 114 mm within 28 s and yield a capillary parameter (K/reff) of 1.49 μm. Moreover, MSMGW on the material of alumina with advantages of excellent machining property and technology maturity, and working fluid of DI water with high vaporization latent heat and wide operating temperature range, exhibits the maximum capillary performance, indicating its highly promising prospects for high-performance ultrathin ceramic heat pipes.