Effects of sintering temperature and holding time on the morphologies and properties of Wf/W-Dia/W composite prepared by SPS

Abstract

To improve the irradiation and high thermal load stability of W matrix, tungsten fiber/tungsten-diamond/tungsten (W_f/W-Dia/W) hierarchical composite was prepared by SPS process, and the effects of sintering temperature and holding time on the microstructure, thermal conductivity and thermal shock of W_f/W-Dia/W composites were investigated. The results showed that the relative densities of both W_f/W composites and Dia/W composites were increased with the increase of sintering temperature and holding time. When the sintering temperature and holding time were 1650 °C and 5 min, the higher relative densities were obtained for both composites, which were 98.97 % and 98.58 %, respectively. The recrystallization behavior of W fiber and W matrix was clear with the increase of sintering temperature and holding time. As the sintering temperature and holding time increased, W-C interfacial reaction was more obvious and a more continuous interfacial layer was formed at Dia/W interface, which helped to improve the thermal conductivity of composites, with the highest thermal conductivity of 234 W m⁻¹ K⁻¹. The thermal shock results showed that W_f/W-Dia/W composite with higher relative density and thermal conductivity had better thermal shock resistance. The finite element simulation results revealed that W_f/W-Dia/W composite can effectively alleviate the thermal stress under the cyclic thermal load of 20 MW/m².