热喷涂纳米陶瓷层单向荷载应力分布有限元分析

Finite Element Analysis of Stress Distribution of Thermally Sprayed Nanostructured Ceramic Coating under Unidirectional Load

为了探讨陶瓷涂层的微观结构(孔隙及裂纹)对涂层断裂特性的影响,采用大气等离子喷涂技术制备了纳米Al2O3/TiO2陶瓷层。以有限元分析软件模拟了纳米结构陶瓷涂层在单向载荷作用下的应力分布,采用扫描电子显微镜(SEM)研究了其微观结构、内部存在的孔隙和裂纹等缺陷,将涂层的缺陷简化为大、中、小孔隙及裂纹,建立了涂层截面二维有限元模型,探讨了涂层受到单向荷载作用时的变形及等值应力分布。结果显示:涂层的小孔隙对应力分布影响不大,相邻孔隙的等值应力会发生叠加;涂层中孔隙的角度分布及孔隙距离对最大等值应力有影响,等值应力最大处最有可能产生裂纹。

Nanostructured Al2O3/TiO2 ceramic coating was prepared by air plasma spraying.The stress distribution in as-sprayed ceramic coating under unidirectional load was investigated using finite element analysis.The microstructure as well as internal pores and cracks was observed using a scanning electron microscope.The defects in the coating were simplified and classified into pores with a large size,medium size and small size as well as cracks,and then two-dimensional finite element model of the cross-section of the coating was established.The deformation and equivalent stress distribution of the coating under unidirectional load were analyzed.It was found that the small pores in the coating had little effect on the stress distribution,and the equivalent stress of adjacent pores was overlapped.Besides,the angle distribution and spacing of the pores had effect on the maximum equivalent stress,and cracks were liable to emerge at the locations with the maximum equivalent stress.