Evaluation of critical stress for microcracking in alumina ceramics by acoustic emission.
Evaluation of critical stress for microcracking in alumina ceramics by acoustic emission.
复制标题
通过声发射评估氧化铝陶瓷微裂纹的临界应力。
DOI：
10.1299/kikaia.57.504
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
H. Nishimura
中科院分区：
文献类型：
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作者：
S. Wakayama;Takashi Koji;H. Nishimura
利用声发射技术对氧化铝陶瓷弯曲过程中的微断裂过程进行了评价。对不同尺寸的试件进行了弯曲试验，研究了试件尺寸对微断裂过程的影响。在最终的失稳断裂之前，观察到每个试件的声发射模式中有一个显著的点，在该点上声发射事件和能量都迅速增加。重要的是，这些点的表观应力与声发射阈值水平和试件大小无关。用荧光染料渗透法确定了应力对应于由于微裂纹和/或孔洞的结合而形成主裂纹的临界应力。考虑到微断裂过程，讨论了脆性材料强度的统计处理方法。因此，临界应力可以作为陶瓷材料的新的评价参数，它与金属的屈服强度相当。
The microfracture process during the bending tests of alumina ceramics was evaluated by the acoustic emission technique. Specimens with different dimensions were used for the bending tests in order to investigate the dependence of the microfracture process on the specimen size. A remarkable point in the AE generation pattern of each specimen, at which both AE events and energy increased rapidly, was observed before the final unstable fracture. It is important that the apparent stress at those points is independent of the AE threshold level and specimen size. Using the fluorescent dye penetrant method, it has been made clear that the stress corresponds to the critical stress for the main-crack formation due to the coalescence of microcracks and/or pores. Considering the micro-fracture process, statistical treatment for the strength of brittle materials has been discussed. Consequently, it was concluded that the critical stress can be the new evaluation parameter, which is equivalent to yield strength in metals, for ceramic materials.