Manufacturing of sintered aluminum powder wicks by the liquid phase enhance sintering method for aluminum heat pipes

The aluminum heat pipes have the advantages of lightweight and low-cost, which are widely applied to space satellites. The wick is the critical component of the heat pipe which provides the capillary pressure. Unfortunately, the performance of the aluminum heat pipes is limited by the wicks, which are difficult to manufacture due to the barriers of Al2O3 thin film during the aluminum powder wicks' sintering process. To overcome this problem, a novel sintered aluminum powder wick manufactured by the liquid phase enhance sintering (LPES) technology based on element doping and vacuum sintering was proposed in this work. Considering the material compatibility between the aluminum and working fluid, the brazing powder rich in Si was chosen to be doped to promote the formation of sintered necks. The mechanism of the LPES promoted by the Si was analyzed by thermodynamic and element distribution analysis. The wick is lightweight whose density is only 22.60% and 74.26% of the densities of copper and aluminum. The wettability and capillary performance of the wicks were also studied. The results show that all the samples are superhydrophilic with the working fluids of ethanol and acetone. The sample of CS15 (coarse pure aluminum powder with 15 wt. % brazing powder) has the best wettability and capillary performance in acetone, whose infiltration time, capillary rise height, and wicking coefficient are about 69.50 ms, 106.39 mm, and 12.35 mm/s(0.5), respectively. The work provides a feasible approach to manufacturing lightweight and low-cost sintered powder wicks for aluminum heat pipes.