Research Of Superwicking Materials For Cooling High-heat Flux Electronics

The current trends in miniaturization of electronic devices and integrated circuits cause a significant increase of heat flux released by them.The traditional heat dissipation materials used in cooling of electronics fail to provide proper cooling of novel high heat flux electronic devices,giving rise to such problems as high energy consumption,uneven heat dissipation,and hot spot damages.To cope with these problems,novel heat dissipation materials based on surface capillarity were developed in this work.Two kinds of micro-nano capillary structures were fabricated on the surface of titanium alloy material(Ti-6Al-4V)by femtosecond laser micro-nano fabrication technology.One is an array of parallel microgrooves(one-dimensional array of microgrooves)with average microgroove spacing and depth of 80 and 75 μm,respectively.The other is a two-dimensional array of microcolumns with average spacing and depth of 100 of 52 μm,respectively.The surface of the two-dimensional capillary microcolumn array is additionally textured with laser-induced periodic surface structures(LIPSS),which enhance the overall capillary action of this material.Both kinds of the created capillary surface structures make the liquid to spread rapidly on the surface of the materials and form a very thin water film(less than 100 μm)that has a contact angle of approximately 0° in a very short time(less than 1 s),demonstrating excellent wicking functionality.The capillary spreading and evaporation rate of water on the surface of one-dimensional titanium alloy were investigated experimentally in a temperature range of 23 – 230 ℃.Under the action of strong capillary force,the liquid can rapidly flow on the surface of the created material at low temperatures(23,40,60,and 80 ℃),medium temperatures(100,120,140,and 160 ℃)and even at high temperatures(180,200,and230 ℃).In the low temperature range,the water spreading distance during the first 100 ms increases from 14.8 mm at 23 ℃ to 17.2 mm at 80 ℃.Then a uniform water film forms on the material surface,making liquid to evaporate rapidly.Under medium and high temperature conditions,the liquid quickly spreads and evaporates on the surface of the material due to combined action of capillary force and boiling,causing the evaporation time to decrease from 3219 ms at 100 ℃ to 1204 ms at 230℃.For two-dimensional titanium alloy material,the capillary spreading and evaporative functionalities were studied in a temperature range of 23 – 80℃.The experiments show that water quickly spreads over the surface and evaporates.The maximum water spreading velocity is measured to be 250 mm/s,exhibiting excellent superwicking performance.The two superwicking titanium alloy materials developed in this research demonstrate long-term superwicking performance.The tests performed over the time period of 6 months did not show any significant wicking degradation.The created materials are suitable for liquid-gas phase change cooling devices due to their strong and durable superwicking functionality.Therefore,the two kinds of micro-nano superwicking titanium alloy materials created in this study are expected to provide new methods and material support to the development of high heat flux electronic devices,providing cooling with reduced energy consumption and high efficiency of heat dissipation.These materials have important academic research value and broad engineering application prospects.