陶瓷材料裂纹愈合研究进展

Research Progress in Crack Healing of Ceramics

分析了裂纹愈合的动力和阻力,动力来源于毛细管力和化学势差异,而阻力是裂纹面运动到平衡间距要克服的能垒和裂纹尖端位错运动需要克服的塑性变形功;综述了陶瓷材料裂纹愈合研究方法:目前所涉及的多为Al2O3、Si3N4、SiC或其复合材料的热压烧结材料,主要用维氏硬度计法获得裂纹,影响愈合效果的主要因素有化学成分与气氛、温度及时间、预制裂纹尺寸及应力等,愈合机理主要是扩散愈合和氧化反应填充愈合,并可用相应的动力学方程描述;指出今后需要解决的问题是拓宽所研究的材料体系并完善实验手段、系统研究愈合条件的影响和愈合机理。

The study on crack healing of ceramic materials has an extensive application in improving material properties, prolonging their service lives, saving resources and protecting environment. In this paper, the driving force and resistance of creak healing are analysed. The driving forces are from capillary force and chemical potential differ- ence, and the resistance forces are activation energy for crack surface to reach its balance distance and plastic deforma- tion work for dislocation movement of crack tip. The study method of crack healing of ceramic materials are reviewed. The present materials concerned are mostly AI2 03, Si3 N4 , SiC and their eompsites prepared by hot-press sintering. A pre-erack is mainly introduced into specimens by using vickers hardness tester. The main factors influencing healing re- sults are chemical composition and atmosphere, temperature and time, the size of preeraek and stess, etc. The diffu- sive healing and oxidation filling healing are two main healing meehamisms and can be described by corrsponding kinetic equations. The problems needing to be solved further are also suggested that are the study on other materials, the perfection of the method of experiment and the systematical study on effects of healing conditions and healing mechanism.