冷却介质温变对陶瓷材料热冲击行为的影响

Effects of the temperature change of cooling medium on thermal shock behavior of ceramics

系统研究了陶瓷试件以纵向姿势进入冷却介质时,浸入式热冲击过程中冷却介质的温度变化和汽化吸热现象的机理,指出了热冲击过程中冷却介质的温度变化造成了试件先后入水部分裂纹差异。发现了热冲击过程中的汽化吸热现象会对试件造成剧烈的热冲击,对陶瓷试件的表面裂纹形貌、长度和三点弯残余强度均造成显著的影响。最后,指出了目前常用的热冲击温差存在的问题及其对陶瓷材料抗热冲击性能的表征和评价造成的影响。

In this research,with all ceramic specimens entering cooling medium in longitudinal position,the mechanism of temperature change and the vaporization and heat absorption of cooling medium in immersion method were studied.It is pointed out that the temperature change of the cooling medium during thermal shock process causes the differences of cracks between the first and later water-entry part.It is found that the vaporization and heat absorption of cooling medium can cause severe thermal shock to the ceramic specimen,which has a significant effect on the surface crack morphology,length and three-point bending residual strength.Finally,the problems of the commonly used thermal shock temperature difference and its influence on the characterization and evaluation of thermal shock resistance of ceramic materials are pointed out.