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本工作制备了一种添加稀土氧化物的热压氮化硅陶瓷,其抗弯强度从室温到1300℃可保持在800—900 MPa,1400℃时为680 MPa,室温断裂韧性值为4.38—4.96 MPa m~(1/2)。X光扫描电子显微镜、电子探针及能量色散谱分析表明,这种材料由细小的β-Si_3N_4晶粒、α-Si_3N_4晶须、四方形含La晶体和含La玻璃相组成。对断口的观察发现这种陶瓷直到1400℃仍以穿晶断裂为主。此外,还就添加剂对强度和断裂韧性的影响进行了讨论。
This work prepared a rare earth oxide-added silicon nitride ceramic, the flexural strength from room temperature to 1300 ℃ can be maintained at 800-900 MPa, 680 ℃ at 680 MPa, room temperature fracture toughness value of 4.38-4.96 MPa m ~ (1/2). X-ray scanning electron microscopy, electron probe and energy dispersive spectroscopy analysis show that the material consists of fine β-Si 3 N 4 crystal grains, α-Si 3 N 4 whiskers, tetragonal La-containing crystals and La-containing glass phases. Observation of the fracture found that this ceramic was still predominantly transgranular until 1400 ° C. In addition, the effects of additives on strength and fracture toughness are also discussed.