Abstract
UDC 620:22
High temperature corrosion of metals and alloys can be controlled by the use of inhibitors. In this work, the role of a superficially applied CeO2 coating to combat high temperature corrosion of some superalloys such as Superfer 800H (Alloy A), Superco 605 (Alloy B) and Superni 75 (Alloy C) has been investigated. An accelerated corrosion testing of the coated as well as bare superalloys was done in a molten salt environment (Na2SO4–60%V2O5) at 900°C for 50 cycles. The weight change, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Probe Micro-Analysis (EPMA) of the exposed specimens were carried out to characterize the oxide scales. The percentage decrease in the weight gain in alloys A, B and C, with superficially applied CeO2, was found to be 23, 35 and 68%, respectively. It was concluded that ceria (ceric oxide) was most effective in reducing the corrosion rate in alloy C.
Keywords: superalloys, hot corrosion, inhibitors, oxide additives.