纳米氧化锆热障涂层组织结构和抗热冲击性能分析

采用大气等离子喷涂技术制备了纳米氧化锆热障涂层和常规热障涂层.利用FESEM和XRD对纳米氧化锆热障涂层的组织结构和物相组成进行分析.系统研究了两种热障涂层的抗热冲击性能.微观组织分析结果表明,纳米氧化锆热障涂层展现出独特的纳米—微米复合结构,包括柱状晶和未熔融或部分熔融纳米颗粒.非平衡四方相是涂层的主要物相.抗热冲击性能试验结果表明,纳米氧化锆热障涂层拥有更为优越的抗热冲击性能,这主要得益于其相对致密的结构以及微裂纹、纳米晶粒、小孔径孔隙的应力缓释作用.热应力失效是涂层失效的主要原因.

Analysis of microstructure and thermal shock resistance of nanostructured zirconia thermal barrier coatings

Air plasma spraying was applied to prepare the nanostructured and conventional zirconia thermal barrier coatings. The microstructure and phase composition of the as-sprayed coatings were determined by the FESEM and XRD. The thermal shock resistance of these two coatings have been systematically investigated and compared. The results indicated that the nanostructured TBCs exhibited a unique complex structure consisting of columnar grains and non-molten or partial molten nanosized particles. The predominant phase of the coatings was metastable tetragonal phase. The experimental results of the thermal shock resistance showed that the nanostructured TBCs possessed better thermal shock resistance compared with the conventional coatings. This phenomenon was ascribed to the relatively densified coatings, microcracks, nanosized grains and fine porosity which could effectively release the thermal stress. And the thermal stress was the main reason leading to the failure of the coatings.