The ESIS Technical Committee for Ceramics (TC6) is running a joint program to characterise a commercial silicon nitride ceramic with respect to all properties necessary to a proper design process. In this paper some preliminary results of measurements on the ESIS Reference Silicon Nitride are presented: the room temperature 4-pt. bending strength is around 870 MPa and the 3-pt. bending strength is around 990 MPa. These two data clearly demonstrate the volume dependence of strength, which can consistently be described with the Weibull theory and a Weibull modulus of about 15. The room temperature fracture toughness of the material is 4,9 MPam{sup}(1/2) (determined with the SEVNB method). IF-toughness values are between 4,8 to 7,9 MPam{sup}(1/2). Although some sub-critical crack growth exists at room temperature (the crack growth exponent is around 50), severe time dependent damage starts around 1000°C.
展开▼
机译:IERS陶瓷技术委员会(TC6)正在运行一个联合程序,以表征相对于适当设计过程所需的所有性质的商业氮化硅陶瓷。本文介绍了对EERS参考氮化硅测量的一些初步结果:室温4-PT。弯曲强度约为870 MPa和3-PT。弯曲强度约为990 MPa。这两种数据清楚地证明了强度的体积依赖性,这可以一致地用Weibull理论和约15的Weibull模量来描述。房间温度断裂韧性为4,9mPam {sup}(1/2)(用SEVNB方法确定)。 IF - 韧性值在4,8至7,9mpam {sup}(1/2)之间。虽然室温存在一些亚临界裂纹增长(裂缝生长指数约为50),但严重的时间依赖性损伤从1000°C开始。
展开▼