High toughness alumina ceramics with elongated grains developed from seeds  

作　　者：谢志鹏 高立春 李文超 徐利华 王习东 

机构地区：[1]Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China [2]University of Science and Technology Beijing, Beijing 100083, China

出　　处：《Science China(Technological Sciences)》2003年第5期527-536,共10页中国科学（技术科学英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(Grant No.50172022);Key Laboratory for High Temperature Structural Ceramics and Engineering Ceramic Machining of Tianjin University.

摘　　要：In the present paper, the influence of α-AI_2Ol_3 seeds and sinteringmethods on elongated grain growth and fracture toughness is investigated. The preparation of aluminaceramics started with commercial aluminum hydroxide. Abrasives were introduced to the startingmaterials by wet-grinding of high-purity alumina milling balls. Abrasives, playing the role ofseeds, lowered the transformation temperature of aluminum hydroxide to alumina. Microstructures withelongated grains were developed by hot-pressing for the above calcined powders containingα-AI_2O_3 seeds, and alumina grain shapes changed with the amount of seeds introduced. However,only equiaxed grains were observed for the samples pressureless sintered. Fracture toughness of thealumina ceramics was dramatically improved by elongated grains. For the sample hot-pressed at 1600℃for 2 h under 40 MPa pressure, fracture toughness reached 7.1 MPa·m^(1/2), which is much higherthan that of normal alumina ceramics without elongated grains. In addition, high flexural strengthof 630 MPa for the hot-pressed samples was also obtained.

关 键 词：ALUMINA elongated grains  Α-AL2O3 seeds  aluminum hydroxide  fracture toughness. 

分 类 号：TQ174[化学工程—陶瓷工业]