超音速电弧喷涂涂层中/高温封孔行为

Sealing Behavior of Ultrasonic Arc-sprayed Coatings at Medium and High Temperatures

重点研究了超音速电弧喷涂涂层的中/高温封孔行为,包括氧化和水冷热震测试。结果表明,在400℃中温氧化条件下,常规低温型S100封孔剂出现了明显烧蚀,导致涂层表面和内部通孔直接暴露在大气环境中,涂层出现了较严重氧化。采用S400型中温封孔剂的涂层氧化程度显著低于S100封孔剂。在400℃水冷热震考核中,S100封孔涂层出现明显剥落,S400型涂层抗热震性能则更优。在700℃高温考核条件下,高温型S700封孔剂依然能够较好地填充涂层孔隙,因此涂层的抗氧化性得到提升。通过显微组织分析发现,中/高温封孔剂在温度升高时能够保持较好的稳定性,对涂层表面及内部孔隙可形成有效覆盖和填充,因此阻隔了外界氧气的渗透,进而提升了涂层抗氧化性和抗剥落性。

In this paper,the medium and high-temperature sealing behavior of the coatings made by ultrasonic arc spray technique was studied.The results showed that the low-temperature S100 sealing agent got obvious burning at the medium temperature of 400℃,resulting in the direct exposing of the surface and internal through-pores in the gas environment,which caused heavy oxidation of the coating.The oxidation rate of the coatings was much lower when using the medium-temperature S400 sealing agents.In the water-cooling thermal shock testing at 400℃,heavy spallation took place in the coating sealed by S100 while the coating sealed by S400 performed better resistance.In the testing conditions at 700℃,the high-temperature S700 sealing agent well filled the pores in the coating,which improved the oxidation resistance.It was found that the medium and high-temperature sealing agents performed good stability at the increased temperatures and effectively covered the coating surface or filled the internal pores.Therefore,the inward diffusion of the out-coming oxygen was hindered,and the oxidation resistance and the spallation resistance of the coatings were improved.