Comparative studies on the hot corrosion behavior of air plasma spray and high velocity oxygen fuel coated Co-based L605 superalloys in a gas turbine environment

An improvement in the corrosion resistance of alloys at elevated temperature is a factor for their potential use in gas turbines. In this study, Co Ni Cr Al Y has been coated on the L605 alloy using air plasma spray(APS) and high-velocity oxygen fuel(HVOF) coating techniques to enhance its corrosion resistance. Hot corrosion studies were conducted on uncoated and coated samples in a molten salt environment at 850°C under cyclic conditions. Thermogravimetric analysis was used to determine the corrosion kinetics. The samples were subjected to scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction for further investigation. In coated samples, the formation of Al2O3 and Cr2O3 in the coating acts as a diffusion barrier that could resists the inward movement of the corrosive species present in the molten salt. Coated samples showed very less spallation, lower weight gain, less porosity, and internal oxidation as compared to uncoated sample.HVOF-coated sample showed greater corrosion resistance and inferred that this is the best technique under these conditions.

超音速火焰喷涂Ni粒子特性数值仿真

在超音速火焰流场数值模型的基础上,应用离散惰性粒子模型和粒子追踪法,建立了三维分析模型,对超音速火焰(SO/AF)喷涂粒子速度特性和温度特性进行了数值模拟。研究了不同参数状态下粒子的动态行为以及直径对火焰流速度和温度的影响,揭示了超音速火焰喷涂粒子的速度和温度变化规律。数值结果表明:在SOF、SO-AF、SAF 3种工作状态下,粒子的出枪速度和温度依次下降,粒子加速出枪以后,还将在一定距离内加速加温;随着粒子直径的增加,粒子速度、温度梯度均减小。该项研究对制备优质涂层具有重要意义。