权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

High-temperature Deformation and Fracture of Ceramics

陶瓷的高温变形与断裂

基本信息

批准号：
08455303
负责人：
OKAMOTO Yasunori
金额：
$ 2.69万
依托单位：
Kyoto Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08455303/
关键词：
Ceramics Microstructure Deformation Fracture Diffusion Grain growth Grain boundary High temperature

项目摘要

Fine and dense ceramic materials with controlled microstructures, including alumina, mullite, forsterite, stabilized zirconia and their composites, were fabricated by using various methods. Small amounts of additives, e.g., MgO or ZrO_2 in alumina, were introduced to control the microstructures, which affected significantly high-temperature mechanical properties of the materials. The hightemperature deformation of fine grained alumina is rate-limited by interface reaction, accompanied with hardening with strain due to dynamic grain growth. However, the addition of an oxide such as zirconia, which segregates at grain boundaries, suppresses appreciably the static and dynamic grain growth, and furthemore affects the yield/flow stress, suggesting that diffusivity or mobility of ions through grain boundaries depend on grain boundary compositions. Fracture and deformation of ceramic composites such as alumina-zirconia (AZ), mullite-zirconia (MZ) and mullite-alumina (MA), were investigated at high temperatures. In AZ materials, high temperature deformation and dynamic grain growth were depressed as compared with pure fine-grained alumina, which may be due to grain boundary segregation of zirconium as in the case of the alumina doped with small amounts of ZrO_2. In MZ and MA materials, experimental data concerning delayd fracture and slow crack growth were obtained and analyzed. Forsterite polycrystals fabricated by sol-gel derived powders were tested to study the high-temperature deformation. Effective diffusion coefficients for rate-determining species were obtained, showing the effects of residual MgO and glassy phases at grain boundaries.

采用多种方法制备了氧化铝、莫来石、镁橄榄石、稳定氧化锆及其复合陶瓷材料。少量的添加剂，例如，在氧化铝中引入MgO或ZrO_2来控制材料的微观结构，对材料的高温力学性能有重要影响。细晶氧化铝的高温变形受界面反应的速率限制，并伴随着动态晶粒长大引起的应变硬化。然而，添加氧化物，如氧化锆，在晶界偏析，抑制明显的静态和动态晶粒生长，并进一步影响屈服/流动应力，这表明通过晶界的离子的扩散率或流动性取决于晶界组合物。研究了氧化铝-氧化锆（AZ）、莫来石-氧化锆（MZ）和莫来石-氧化铝（MA）陶瓷复合材料在高温下的断裂和变形。与纯细晶氧化铝相比，AZ材料的高温变形和动态晶粒生长受到抑制，这可能是由于锆的晶界偏聚，如在氧化铝中掺入少量ZrO_2的情况。在MZ和MA材料中，获得了延迟断裂和缓慢裂纹扩展的实验数据，并进行了分析。采用溶胶-凝胶法制备镁橄榄石多晶，研究其高温变形性能。有效的扩散系数的速率决定物种，显示在晶界的残余MgO和玻璃相的影响。