等离子喷涂纳米氧化锆涂层的热震失效机理研究

Study on thermal shock failure principle of nanostruc-tured zirconia coating by atmospheric plasma spraying

摘要:

采用合理的喷涂工艺参数制备了纳米氧化锆涂层并在1100度下测试了其热震性能，利用XRD,SEM和TEM对涂层的结构及表面形貌进行了分析。实验结果显示孔隙或早期存在的微裂纹附近的纳米颗粒在热震实验过程中会长大。通过对结构分析，我们提出了在循环应力作用下纳米涂层的失效机理。即随着纳米结构涂层中的大多数或者全部的纳米颗粒长大后，纳米结构随之变为准微米结构，其热震失效模式将类似于传统微米涂层的失效方式—裂纹形成，扩展直至最后涂层剥落。

Abstract:

Nanostructured zirconia coating was prepared based on reasonable spraying technical parameters and corresponding thermal shock property of as-sprayed coating has been examined at 1100 篊. The structure and the surface morphology of coating have been analyzed using XRD, SEM and TEM. Experimental results show nanoparticles close to pre-existing microcracks or pores grow during thermal shock process. Based on the detailed analysis of the structure, a rational mechanism has been proposed for the failure of as-prepared coating suffered circular stress. That is, with the growth of most or all of the nanoparticles, the nanostructured zirconia coating correspondingly changes into the quasi-microstructured coating, then the thermal shock failure mode of the resulting coating can be interpreted as follows: the formation of cracks results in the propagation of cracks, which is followed by the spallation of coating, just as the failure mode of traditional micro coating.