Critical crack-healing condition for SiC whisker reinforced alumina under stress
Critical crack-healing condition for SiC whisker reinforced alumina under stress
复制标题
DOI：
10.1016/j.jeurceramsoc.2004.09.021
复制
发表时间：
2005-11-01
影响因子：
5.7
通讯作者：
Ando, K
中科院分区：
文献类型：
--
作者：
Nakao, W;Ono, M;Ando, K
以提高断裂韧性和裂纹愈合能力为目标，开发了SiC晶须增强氧化铝，这里称为“氧化铝（w）”。复合材料在1200 ℃下在空气中在升高的静态和循环应力下裂纹愈合8小时。研究了裂纹愈合后复合材料在1200 ℃下的弯曲强度。氧化铝裂纹愈合的临界静应力为250 MPa，临界循环应力为300 MPa。考虑到裂纹的扩展是时间依赖性的，发现氧化铝裂纹愈合过程中的每种条件的阈值应力（w）为250 MPa。结果表明，裂纹愈合过程中的门槛应力强度因子为3.8 MPa M-1/2。将相同的实验条件应用于破裂并在Ar中在1300 ℃下退火1小时的试样，以去除裂纹尖端处的拉伸残余应力。因此，裂纹愈合过程中的阈值应力强度因子被认为是3.2 MPa m（1/2）的试样裂纹愈合与退火。氧化铝裂纹愈合期间的阈值应力强度因子（w）被选择为3.2MPa m（1/2），以便于与裂纹愈合期间的阈值应力强度因子的值进行比较。残余应力略大于本征值。(c)2004爱思唯尔有限公司保留所有权利。
Alumina reinforced by SiC whisker, called here "alumina(w)" was developed with the objective of improving fracture toughness and crack-healing ability. The composites were crack-healed at 1200 degrees C for 8 h in air under elevated static and cyclic stresses. The bending strength at 1200 degrees C of the crack-healed composites were investigated. The threshold static stress during crack-healing of alumina(w) has been determined to be 250 MPa, and the threshold cyclic stress was found to be 300 MPa. Considering that the crack growth is time-dependent, the threshold stress of every condition during crack-healing of alumina(w) was found to be 250 MPa. The results showed that the threshold stress intensity factor during crack-healing was 3.8 MPa M-1/2. The same experiment conditions were applied to specimens cracked and annealed at 1300 degrees C for 1 h in Ar, to remove the tensile residual stress at a tip of the crack. Thus, the threshold stress intensity factor during crack-healing was found to be 3.2 MPa m(1/2) for the specimens crack-healed with annealing. The threshold stress intensity factor during crack-healing of alumina(w) was chosen to be 3.2 MPa m(1/2) to facilitate comparison with the values of the threshold stress intensity factor during crack-healing. The residual stress was slightly larger than the intrinsic value. (c) 2004 Elsevier Ltd. All rights reserved.