Effect of Low-Temperature Thermal Oxidation on the Capillary Performance of Sintered Copper Powder Wicks

In this study, a composite powder capillary wick is prepared, manufactured by sintering copper powder and surface treated by low-temperature thermal oxidation. It is used to improve the performance of the capillary wick. The forced flow method and infrared imaging method are used to test the permeability and capillary performance of the samples. The effects of different oxidation temperatures on the performance of capillary wick are investigated. The experimental results show that the wetting performance of the oxidized samples is significantly enhanced. With the increase of oxidation temperature, the permeability decreases. The capillary height and velocity of the thermally oxidized samples are significantly higher than those of the untreated capillary wick. However, the oxidation temperature needs to be adjusted to obtain the best capillary performance. The highest capillary performance is found at oxidation temperature of 300°C, with an increase of 46% compared to the untreated ones. Comparisons with other composite wicks show that the sample with an oxidation temperature of 300°C has competitive capillary performance, making it a favorable alternative to two-phase heat transfer device. This study shows that combining low-temperature thermal oxidation technology with powder sintering is a convenient and effective method to improve the capillary performance of powder wicks.