等离子喷涂纳米氧化锆涂层的热震失效机理研究（英文）

Thermal Shock Failure Mechanism of Nanostructured Zirconia Coating by Atmospheric Plasma Spraying

采用合理的喷涂工艺参数制备了纳米氧化锆涂层并在1100℃下测试了其热震性能,利用X射线衍射(XRD),扫描电镜(SEM)和透射电镜(TEM)对涂层的结构及表面/界面形貌进行了分析。根据实验分析结果提出了纳米涂层的热震失效机理,即孔隙或早期存在的微裂纹由于能提供更好的生长空间而使得附近的纳米颗粒在热震实验过程中优先长大,其长大过程会造成新的微裂纹生成,从而导致其它的纳米颗粒长大。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。

Nanostructured zirconia coatings has been prepared based on reasonable spraying technical parameters and the corresponding thermal shock property of the as-sprayed coating was examined at 1100 oC. The structure and the surface/interface morphology of the coatings have been analyzed using X-ray diffraction（XRD）, metallographic microscope, scanning electron microscopy（SEM）, energy dispersive spectrum（EDS） and transmission electron microscopy（TEM）. Based on the detailed analysis of the structure and phase composition, a rational mechanism has been proposed for thermal shock failure of the coating. Compared with other nanoparticles, those particles close to pores and pre-existing microcracks would preferentially grow up during the thermal shock process due to a better growth space. The growth of these nanoparticles is conducive to the formation of new microcracks which would lead to the growth of the other nanoparticles. With the growth of most or all of the nanoparticles, the nanostructured zirconia coating correspondingly changes into the quasi-microstructured coating. The thermal shock failure mode of the as-sprayed coating is similar to that of traditional zirconia thermal barrier coatings（TBCs）.