Capillary performance of vertically grooved wicks on laser-processed aluminum surfaces with different wettability

Abstract

Ultra-thin heat pipes have been widely used for thermal management of electronic components. The capillary performance of the wicking structure is an essential factor that affects its heat transfer capability. In this study, superhydrophilic and superhydrophobic background surfaces were prepared on aluminum sheets using a nanosecond fiber laser. Superhydrophilic grooves with a width of 0.1-0.4 mm were fabricated on surfaces with different wettability by laser processing. The effects of the background wettability on the capillary performance of the grooves were investigated. When the groove widths were 0.1-0.2 mm, the water in the groove rose the fastest on the superhydrophobic background surface. As the groove width increased to 0.3-0.4 mm, the water in the groove on the superhydrophilic surface rose the most rapidly. Furthermore, the water absorption of grooves with the same width on the superhydrophilic background surface was always greater than that of the grooves on the other two surfaces. Therefore, a matching wettable background surface should be selected according to application requirements. A superhydrophobic background surface can be chosen when a faster rise in the speed of the water in the groove is preferred. In contrast, a superhydrophilic background surface is beneficial for improving the water absorption capacity. The water absorption of the groove on the superhydrophilic background surface reaches a maximum of 6.8 mg with a groove width of 0.4 mm, and the capillary performance parameters can reach 4.26e-7 N, which is 100.9 % enhanced over the pristine background surface. Thus, this study provides new ideas for improving the capillary performance of vertically grooved wicks.