Preparation of high thermal conductivity and high strength silicon nitride ceramics with YbH_2-MgO system as sintering aid

Using YbH_2-MgO system as a sintering aid, a two-step sintering method was used to prepare high thermal conductivity and high strength silicon nitride ceramics. The densification behavior, phase composition, microscopic morphology, and thermal conductivity of YbH_2-MgO on silicon nitride were studied. And the influence of flexural strength. In the pre-sintering stage, YbH_2 reduces SiO_2 and generates Yb_2O_3 in situ at the same time, and then forms the "anoxic-nitrogen-rich" liquid phase. This liquid phase is not only conducive to the growth of crystal grains, but also more conducive to hindering the generation of lattice oxygen. Compared with the Yb_2O_3-MgO additive system, the β-Si_3N_4 has larger grain size, fewer lattice defects, and low thermal conductivity. There are fewer phases, and the thermal conductivity can reach 131.15 W·m~(–1)·K~(...