MULTIPLE CRACKING IN FUNCTIONALLY GRADED CERAMIC-METAL COATINGS
MULTIPLE CRACKING IN FUNCTIONALLY GRADED CERAMIC-METAL COATINGS
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DOI：
10.1016/0020-7683(94)00267-z
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发表时间：
1995-10-01
影响因子：
3.6
通讯作者：
WANG, L
中科院分区：
文献类型：
--
作者：
BAO, G;WANG, L
功能梯度涂层，如先进金属和合金上的热障涂层，可以承受热负荷和机械负荷时的多个裂纹。涂层的断裂行为的一个特殊特征是涂层的梯度，它可以用金属的局部体积分数来表征。为指导涂层级配设计，使裂纹损伤最小化，对功能梯度陶瓷/金属涂层中多裂纹的裂纹驱动力进行了断裂力学研究。金属基体和陶瓷/金属涂层被视为线性弹性体，涂层的弹性特性随膜厚变化。系统的有限元计算的涂层中的裂纹的能量释放率确定的涂层的级配，裂纹长度，和裂纹密度;机械和热载荷被认为是。研究发现，与纯陶瓷涂层相比，涂层的梯度化可以显著降低裂纹驱动力。在机械荷载作用下，不同级配对裂纹驱动力的影响较小。然而，在热负荷下，涂层级配的影响可能是显着的。讨论了结果对功能梯度涂层材料设计的影响。
Functionally graded coatings such as thermal barrier coatings on advanced metals and alloys can sustain multiple cracking upon thermal and mechanical loading. A special feature pertaining to the fracture behavior of coating is the coating gradation which can be characterized by the local volume fraction of metal. To guide the design of coating gradation so that cracking damage can be minimized, a fracture mechanics study is made of the crack driving force for multiple cracks in functionally graded ceramic/metal coatings. The metal substrate and the ceramic/metal coating are taken as linear elastic, with the elastic properties of the coating Varying through the film thickness. Systematic finite element calculations are made for the energy release rate of the cracks in the coating as determined by the coating gradation, crack length, and the crack density; both mechanical and thermal loads are considered. It is found that compared with the pure ceramic coating, gradation of the coating can significantly reduce the crack driving force. It is also found that under mechanical loading the effect of different gradations on the crack driving force is relatively small. However, under thermal loading the influence of coating gradation can be significant. The implications of the results for the material design of functionally graded coatings are discussed.