【摘要】 将粒径为 3 0～ 3 5nm的 β -SiC粉 ,加入亚微米尺寸的α-Al2 O3粉料中 ,通过无压烧结工艺 ,制备出了Al2 O3/SiC纳米复相陶瓷 .烧结体相对密度达到 98.82 % ,抗弯强度和断裂韧性分别达到 489MPa和 6.67MPa·m1 / 2 .SEM分析发现 :纳米SiC颗粒镶嵌于氧化铝晶界 ,形成了由Al2 O3-SiC -Al2 O3晶粒间搭桥联结的界面与SiC -Al2 O3之间牢固结合的相界组成的复合界面 ,改善了晶界结构 ,极大地提高强度和韧性 .同时发现纳米强化相中O2 含量对烧结体密度和组织结构有重要影响 .用Si/C/N非晶复合粉作为强化相也进行了对比实验 .更多还原

【Abstract】 SiC nanometer powder with the mean particle size of 30～35 nm, as the strengthening phases, was added into α -Al 2O 3 powder with the mean particle size of 0.37 μm. The pressureless sintering technology was used to prepare the Al 2O 3/SiC nanocomposite ceramics. The experimental results show that the relative density of the sintered body can reach 98.82%, and the flexural strength and the fracture toughness reach 489 MPa and 6.67 MPa·m 1/2 respectively. The microstructure was observed by means of SEM. It has been found that the grain boundary structure of alumina ceramics consists of both the bridge of“ Al 2O 3-SiC-Al 2O 3”and the phase boundary of “SiC-Al 2O 3”, forming firmly combined composite boundary. This composite boundary raises the strength of the grain boundary, and limits the crack producing and growing only within the grain. The fracture mode is transformed from brittle intergranular fracture to intragranular fracture. Both the sub_structure and nano SiC particles within the grain can slow down the growing speed of cracks and increase strength and toughness greatly. The amount of O 2 existing in nanopowder can bring serious influence to the properties and microstructure of the sintered body. The contrast test that utilizing Si/C/N amorphous compound powder as the strengthening phases was done, too.更多还原