激光喷丸强化CoCrAlY防护涂层 抗高温氧化性能研究

High-Temperature Oxidation Resistance of CoCrAlY Protective Coating Strengthened by Laser Peening

摘要:

利用大气等离子喷涂(Air Plasma Spraying,APS)技术在镍基高温合金表面制备CoCrAlY涂层，在此基础上采用电子束真空蒸镀(Electric Beam Vacuum Deposition,EBVD)技术在涂层表面进一步沉积铝膜，以提高涂层表面Al元素含量。采用激光喷丸(Laser Peening,LP)技术分别对以上两种涂层进行强化处理。采用X射线衍射(X-Ray Diffraction,XRD)和扫描电子显微镜(Scanning Election Microscope,SEM)对比分析LP冲击前后CoCrAlY涂层表面相结构、微观形貌及成分变化。微观结构分析表明，LP处理后APS-CoCrAlY涂层表面粗糙度降低，组织致密性增加；镀铝CoCrAlY涂层经LP处理后，表面Al含量明显增加，β-CoAl相含量提高，且涂层表面晶粒得到细化。1050 ℃抗高温氧化实验结果表明，LP处理涂层表面形成的氧化膜较原始涂层更加平整、致密，且氧化膜厚度明显变薄；此外，镀铝CoCrAlY涂层经LP处理后的抗高温氧化性能最优。

Abstract:

The CoCrAlY coating was deposited on the surface of the nickel-based superalloy by Air plasma spraying (APS). And on this basis, electron beam vacuum deposition (EBVD) method was used to deposit aluminum film on the coating surface in order to increase the Al content. The above two coatings were reinforced by laser peening (LP) technique. X-ray diffraction (XRD) and scanning election microscope (SEM) were used to compare the phase structure, morphology and composition of the CoCrAlY coating before and after LP treatment. The results of microstructural analysis showed that the surface roughness of APS-CoCrAlY coating was decreased, and the microstructure became more compact after LP treatment. The surface Al content of CoCrAlY coating deposited with Al film after LP impact was increased significantly, and the content of β-CoAl phase was increased. The grain size was refined concurrently. The results of high-temperature oxidation test at 1050 °C showed that the oxide film formed on the surface of LP treated coating became smoother and denser than that of the original one, and the thickness of the oxide film was significantly thinner. In addition, the aluminized CoCrAlY coating after LP treatment achieved optimal performance of high-temperature oxidation resistance.