复合喷丸强化对EB-PVD制备CoCrAlY涂层高温氧化性能的影响

Effect of Surface Compound Shot Peening Process on Isothermal Oxidation of CoCrAlY Coatings Prepared by EB-PVD

为了研究复合型的高能喷丸工艺对EB-PVD制备的CoCrAlY涂层的高温氧化性能,采用0.3N、0.3N+0.1N和0.3 N+0.2 N的喷丸强度对CoCrAlY涂层进行了表面强化。观察了喷丸强化前后涂层的表面形貌;测量了喷丸前后涂层的表面粗糙度、表面残余应力、涂层的厚度和截面硬度;对比分析了喷丸前后涂层物相变化以及涂层高温氧化性能。结果表明:复合喷丸强化比普通高能喷丸强化对EB-PVD制备的CoCrAlY涂层的抗高温氧化性能提升更加明显,0.3N+0.1N的复合喷丸工艺对提升涂层的高温抗氧化性能最好。相较普通喷丸工艺,复合喷丸工艺更能明显降低EB-PVD制备的CoCrAlY涂层表面粗糙度,提高涂层的致密度,改善物相结构,进而提升涂层的抗高温氧化性能。喷丸强度大于等于0.3 N时,CoCrAlY涂层表面出现鳞状突出物,导致氧化物在此处择优生长,生成的氧化膜中的应力在此处集中而发生破裂,降低涂层的使用寿命,但复合喷丸能消除该鳞状突出物。

CoCrAlY coatings prepared by EB-PVD were surface shot peened with strength of 0.3 N,0.3 N＋0.1 N and 0.3 N＋0.2 N to study their isothermal oxidation performance after high energy compound shot peening process with different intensity.The surface morphologies of the coatings were observed before and after shot peening.The surface roughness,surface residual stress,thickness and cross-sectional hardness of the coatings were measured after shot peening.The phase change and performance of isothermal oxidation for the CoCrAlY coatings were analyzed after shot peening.The results show that the performance of isothermal oxidation of the CoCrAlY coating prepared by EB-PVD with compound shot peening is improved more than that by common shot peening,and the compound shot peening with strength of 0.3 N＋0.1 N causes the best performance of isothermal oxidation.Compared with common shot peening,compound shot peening process can reduce the surface roughness,increase the density,change the phase structure,and improve isothermal oxidation performance of the CoCrAlY coating.When the shot peening intensity is greater than or equal to 0.3 N,scales form on the surface of CoCrAlY coating and result in preferential growth of TGO herein.Because of TGO film ruptured by stress concentration here,the service life of the coating is degraded.Meanwhile,the compound shot peening can remove the scales.