Thermal Shock Performance of Sintered Pure Tungsten with Various Grain Sizes Under Transient High Heat Flux Test

摘要

Pure tungsten samples with multimodal grain size of 1.85 +/- A 0.84/0.47 +/- A 0.2 mu m (PW1) and grain size of 0.33 +/- A 0.1 mu m (PW2) were prepared by resistance sintering under ultra high pressure. Then the thermal shock performance of both W was evaluated using the electron beam facility with 1 cycle and 5 ms pulse duration at 0.22 GW/m(2). PW1 exhibited higher relative density, thermal conductivity but lower microhardness and bending strength compared with PW2. Furthermore, PW1 displayed slight higher major crack density (smaller major crack distance) while slight smaller major crack width compared with PW2. Besides, the microcracks that only formed in PW2 have the potential to detach W grains from the matrix. Moreover, both samples showed close major crack depth and surface roughness. Thus it can be concluded that PW1 with large grain size showed better thermal shock performance compared with PW2 with small grain size.