【摘要】 以h-BN、ZrO₂、SiC粉体为原料,添加8%（质量分数,下同）的A₂O₃-Y₂O₃为烧结助剂,采用放电等离子烧结技术快速制备了h-BN-ZrO₂-SiC复相陶瓷,研究了纳米SiC颗粒添加量对h-BN-ZrO₂-SiC复相陶瓷的致密化、显微结构及力学性能的影响。结果表明:添加纳米SiC颗粒能有效促进h-BN-ZrO₂-SiC复相陶瓷的烧结和提高其致密度,复相陶瓷的力学性能随SiC添加量的增大而增大,特别是弹性模量的增加比较显著。在添加25%的纳米SiC时复相陶瓷的力学性能较好,此时复相陶瓷的断裂韧性、抗弯强度和弹性模量分别达到3.24 MPa·m^1/2、268.4 MPa和115 GPa。其原因主要是由于细小的SiC颗粒能较好填充复相陶瓷中的空隙,减少相间由于热失配产生的残余应力,增大裂纹扩展时断裂能的消耗,起到晶界钉扎和弥散强化作用,这均有利于复相陶瓷断裂韧性和抗弯强度的提高。更多还原

【Abstract】 h-BN-ZrO₂-SiC multiphase ceramics were prepared rapidly by spark plasma sintering（SPS）with h-BN,ZrO₂ and SiC powders as raw materials and 8%（Al₂O₃+Y₂O₃）as sintering aids.The effects of nano SiC content on the densification,microstructure and mechanical properties of h-BN-ZrO₂-SiC multiphase ceramics were investigated.The results show that the addition of nano SiC particles can effectively promote the sintering and increase density and mechanical properties of the sintered samples at a low sintering temperature.The flexural strength,fracture toughness and elastic modulus all increase with the content increase of nano SiC,especially,the increment of the elastic modulus is obvious.The comparison of all results shows that the sample with the SiC content of 25%has optimal mechanical properties,and the flexural strength,fracture toughness and elastic modulus are 268.4 MPa,3.24 MPa·m^1/2 and 115 GPa,respectively.It is mainly because the nano SiC particles can better play a gap filling,dispersion strengthening and grain boundary pinning effect than ZrO₂,which are beneficial to improve the bonding strength between the phases and reduce the residual stress due to thermal mismatch.As a result,more fracture energy is absorbed during the crack propagation process,and the flexural strength and fracture toughness increase.更多还原