High temperature corrosion behavior of superficially applied CeO2 on some Fe, Co and Ni based super alloys

Abstract

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 super alloys such as Superfer 800H (Alloy A), Superco 605 (Alloy B) and Superni 75 (Alloy C) has been investi gated. An accelerated corrosion testing of the coated as well as bare superalloys was done in a molten salt envi ronment (Na2SO4–60% V2O5) at 900°C for 50 cycles. The weight change, Xray diffraction (XRD), Scan ning Electron Microscopy (SEM) and Electron Probe MicroAnalysis (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.