等离子喷涂制备MoSi_2-CoNiCrAlY纳米复合涂层的结构与性能

Structure and Properties of MoSi_2-CoNiCrAlY Nano-composite Coating by Plasma Spraying

以高能球磨法制备的MoSi2-CoNiCrAlY复合粉末为喂料,利用等离子喷涂技术在GH4169合金表面沉积了MoSi2-CoNiCrAlY涂层,采用X射线衍射仪、激光粒度分析仪和扫描电镜分析了粉末喂料及涂层的相组成和微观结构,并对涂层的显微硬度、抗热震性以及低温氧化行为进行了研究。结果表明:采用高能球磨法制备的粉末喂料是由细小纳米晶组成的多晶体,略为过筛后可直接用于热喷涂;制备的涂层组织致密,孔隙率低,且与基体形成了一定的冶金结合;其显微硬度服从威布尔分布,平均硬度值高达854.4HV0.1,热震失效寿命长达27次,500℃氧化120h后质量增加仅为0.083mg/cm2,且未发生MoSi2的'低温粉化'现象。

MoSi2-CoNiCrA1Y composite coating was deposited on superalloy GH4169 substrate with ball milled nanocrystalline powders by plasma spraying technology. The phase constitution and microstructure of the nano-eomposite feedstock and coating were analyzed by X-ray diffraction （XRD）, laser particle size analyzer and scanning electron microscopy （SEM）. The properties such as microhard- ness, thermal shock resistance and low-temperature oxidation behavior of the coating were also stud- ied. The results show that the milled powder is composed of small nanocrystalline polycrystals which can be used directly for thermal spraying after sieving slightly. The as-sprayed coating is metallurgi- cally bonded with the substrate and has compact structure and low porosity. The microhardness strict- ly fits into the Weibull distribution, and the average values of microhardness and lifetime of thermal shock failure are 854.4HV01 and 27 cycles, respectively. After oxidized at 500~C for 120h, the coat ing has only a small mass increase of 0. 083mg/cm^2 , and the ＂pesting＂ phenomenon of MoSi2 does not occur.