大气等离子喷涂制备莫来石涂层的性能

采用大气等离子喷涂制备莫来石涂层,对涂层进行了热震试验。以OLYCIA m3图像分析软件测定涂层孔隙率,以MH-5-VM型显微硬度仪测定涂层硬度,依照ASTMC633-79标准测定涂层结合强度,以X射线衍射(XRD)和扫描电镜(SEM)表征涂层的相组成和微观形貌。结果表明,莫来石涂层主要由变形颗粒、未熔融粉末及少量孔隙组成,涂层中没有微观裂纹;涂层中含有莫来石晶体和部分非晶态玻璃相;热震过程中,涂层中的非晶转变为晶态莫来石,同时伴随应力释放,导致涂层出现微观裂纹。

Characteristics of Mullite Coatings Prepared by Air Plasma Spraying

The mullite coatings were prepared by air plasma sprayed.The as-sprayed coating were carried out thermal shock experiment.The porosity and microhardness were measured by OLYCIA m3 image analysis software and MH-5-VM microhardness tester,respectively.The bond strength of mullite coatings were determined according to ASTM C633-79 standard.The composition and morphology of the mullite coatings were examined by X-ray diffraction(XRD) and scanning electron microscope(SEM).The results show that as-sprayed coating includes splats grains,partially melted powders and a few pores.The microcracks do not appear in the coating.The as-sprayed coating is largely crystal mullite and only a small quantity of amorphous phase.During thermal shock experiment,amorphous phase in coating changes to crystal mullite and gives rise to stress,leading to microcracks.