电弧离子镀NiCrAlYSi涂层抗高温氧化行为

High Temperature Oxidation Resistance of NiCrAIYSi Coating Deposited by Arc Ion Plating

采用电弧离子镀技术,在镍基高温合金DZ22B表面沉积一层NiCrAlYSi抗高温氧化涂层。利用SEM、XRD、EDS和电子探针等,分析了涂层的微观形貌、组织结构、物相和元素分布规律。研究了涂层和基体在1050℃的静态空气环境中恒温氧化200 h的氧化动力学规律和抗氧化性能。结果表明:沉积态涂层致密均匀,无孔洞等明显缺陷。经热处理后,涂层发生了β-NiAl向γ'-Ni_3Al的转变,主要物相为γ'-Ni_3Al/γ-Ni、β-NiAl和α-Cr相。恒温氧化200 h后,与基体相比,平均氧化速度由0.096 7g/(m^2·h)降到0.0340g/(m^2·h),显著提高了基体的抗高温氧化性能。氧化初期,涂层表面形成了一层均匀致密的α-Al_2O_3保护层,阻止氧向涂层内部扩散,从而大大提高了抗氧化性能。氧化过程中,涂层与基体的界面处发生了元素互扩散现象;主要为Cr元素从涂层向基体的内扩散和Co、W和Y元素从基体向涂层的外扩散。

The high temperature oxidation resistance NiCrAlYSi coating was deposited on nickel-based superalloy DZ22B by arc ion plating. The microstructure, phase and element distribution of the coating were analyzed by SEM, XRD, EDS and electronic probe, respectively. The oxidation behavior of the coating and the substrate were separately investigated at 1 050℃ for 200 h. Results show that the coatings are dense and uniform without obvious holes and other defects. After heat treatment, the transition of β-NiAl to γ＇-Ni3Al occurs and the main phases are γ＇-Ni3Al/γ-Ni, α-Cr and β-NiAl. The average oxidation rate of coated samples and the substrate alloy are 0.034 0g/（m2·h） and 0.096 7g/（m2·h） respectively after 200 h oxidation at a constant temperature of 1 050℃,which indicates that the coatings significantly improve of high temperature oxidation resistance of the substrate. At the early stage of the oxidation, a uniform and dense α-Al2O3 protective layer is formed, preventing the diffusion of oxygen into the interior, thus, greatly improves the oxidation resistance. During the process of the oxidation, the element inter-diffusion occurs at the interface between the coating and the substrate, including the internal diffusion of Cr from the coating to the substrate, and the outward diffusion of Co, W and Y from the matrix to the coating.