Preparation And Properties Of Porous Wick For Loop Heat Pipe

:The nickel porous wicks for loop heat pipe (LHP) were fabricated by the powder metallurgy technology. Through the Archimedes drainage method, scanning electron microscopy (SEM), two homemade apparatuses, and other property test methods, the effects of sintering temperature, time and packing density on porosity, average pore size, microstructure, permeability, capillary pressure, thermal conductivity and compression strength were investigated, respectively. Then the processing technologies of porous wick surface and internal thread were improved. It was shown that:1. With the increasing sintering temperature and packing density, all of the porosity, average pore size and permeability of porous wick decrease. With the increasing sintering time, the porosity and permeability decrease, respectively. However, the maximum capillary pressure reaches at the sintering time of45min. Moreover, with the increasing porosity, the thermal conductivity and compression strength decrease, respectively. After the optimization of parameters, the porous wicks, which show the most excellent comprehensive performance, can be fabricated by sintering at750～800℃for30～45min with the packing density of0.9g/cm3. The porosity, average pore size and permeability are55～64%,1.22～1.41μm and1.2～1.7×10-13m2, respectively. The capillary pressure, thermal conductivity and compressive yield strength are18～26kPa,15～19W/mK and22.8～39.6MPa, respectively. The performance of the porous wick meets the requirements of LHP.2. Based on Darcy’s law and Cotter’s theory, two homemade apparatuses were designed, manufactured and used to measure the permeability and capillary pressure of porous wick, respectively. The results are consistent with the theoretical rules. The two apparatuses are suitable for the nondestructive testing of porous wicks with different shapes and sizes.4. The thread structure in a porous wick can be directly formed by a threaded rod. The method, which combines wax impregnation with machining, reduces the amount of closed pores on the surface of porous wick and improves the surface quality. The porous wicks manufactured by this method meet the processing and assembly requirements of LHP. In this thesis, there are42figures,6tables and83references.