High-current pulsed electron beam(HCPEB)treatment was conducted on CoCrAlY coatings prepared by air plasma sprayed(APS)technology. The microstructural evolutions and hot corrosion properties of CoCrAlY coating performed in Na2SO4/NaCl(mass ratio of 3:1)mixture at 1050 ℃ in static air before and after HCPEB irradiation were analyzed in detail. Microstructural observations reveal that after HCPEB irradiation, the coating surface is melted with thermal sprayed defects disappearing, and the modified surface is significantly changed as interconnected bulged nodules with a compact appearance. With the increment of irradiated pulses, the thickness of the remelted layer and the size of the bulged structures were gradually increase. Moreover, abundant Y-rich Al2O3 particulates and ultrafine grains are formed on the top surface after 30-pulsed HCPEB irradiation. The result of hot corrosion test shows that the initial sample has a poor hot corrosion resistance. The depth of corrosion layer reaches to 20 μm, which existes many microcracks inside after hot corrosion for 20 h. Also aggressive internal oxidation and sulfurization are observed. By contrast, the corrosion layer of the irradiated coating was relatively compact and continuous, the depth of which is only a few microns. During the process of hot corrosion, the protective oxide layer is promoted to form immediately due to HCPEB irradiated effects, which can effectively stop off the reactions with molten salt. The results indicate that the hot corrosion resistance of CoCrAlY coatings irradiated by HCPEB treatment is improved dramatically.%利用强流脉冲电子束技术(HCPEB)对大气等离子喷涂(APS)CoCrAlY 涂层表面进行辐照处理,对HCPEB诱发的微观结构进行详细表征,并考察HCPEB处理前后样品表面在1050 ℃混合盐Na2SO4/NaCl(质量比3:1)条件下的抗热腐蚀性能.结果表明:HCPEB 辐照后原始涂层表面热喷涂结构缺陷消失,表面发生重熔,形成连续的鼓包状结构,且随着辐照次数的增加,重熔层厚度和鼓包状结构的尺寸逐渐增加.30次辐照处理后涂层表面形成大量的Y富集Al2O3颗粒和超细晶结构.热腐蚀试验结果表明,原始涂层抗热腐蚀性能较差,热腐蚀20 h后腐蚀产物发生散裂,腐蚀层深度可到20 μm,且涂层内部存在严重的内氧化和硫化.相比之下,经辐照处理涂层的腐蚀层深度仅有几个微米,且相对较为连续致密.HCPEB 辐照带来的辐照效应促进热腐蚀过程中涂层表面保护性氧化膜的快速形成,有效阻挡熔盐的侵蚀,显著提高CoCrAlY涂层的抗热腐蚀性能.
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