Abstract:
Silicon nitride (Si3N4) ceramics are regarded as a novel category of structural ceramics, exhibiting both high reliability and economy due to their unique physical and chemical properties. To address the difficulty of sintering due to strong covalent bonds and the problem of phase transition regulation,.In this study, high temperature and high pressure sintering technology (HPHT) was utilized in combination with MgO-Y2O3 binary sintering additives (in which the mass ratio of Si3N4: MgO: Y2O3 = 94:3:3) to achieve high temperature and high pressure and liquid-phase synergistic sintering. The effects of binary sintering additives on the sintering process, phase transition behavior, microscopic morphology and mechanical properties of Si3N4 under high pressure were systematically investigated by designing a two-layer comparative experimental assembly to ensure the same sintering temperature. The results show that the liquid phase formed by MgO-Y2O3 accelerates the transformation of α-Si3N4→β-Si3N4 during the sintering process, which reduces the onset temperature of Si3N4 phase transition from 1800 ℃ to 1650 ℃, and at the same time the high pressure promotes grain rearrangement and sintering, and the highly dense Si3N4 ceramics with the optimal specimen Vickers hardness up to 24.5 ± 1.88 GPa are prepared successfully. This finding provides a novel strategy for preparing high-performance Si3N4 ceramics, which is of great significance in the fields of physics and material science.
点击查看大图
下载:
