An Investigation on Hot Corrosion Behaviour of Cermet Coatings in Simulated Boiler Environment

Abstract

In this research work, hot corrosion behaviour of different Cr3C2–NiCr coatings has been investigated. The coatings were deposited on commercially available boiler tube steel with high velocity oxy fuel thermal spraying technique. The uncoated and coated specimens were exposed to elevated temperature in a silicon tube furnace at 700 °C in molten salt environment. The thermogravimetric technique was used to compare the corrosion resistance of different coatings for 50 cycles at high temperature. The microstructures of exposed specimens were evaluated with X-ray diffraction and scanning electron microscopy with elemental compositional analysis. 10Cr3C2–90NiCr and 20Cr3C2–80NiCr coatings provided the higher resistance to corrosion as compared to 100NiCr and 35Cr3C2–65NiCr. The formation of chromium carbide layer on the coated surface and this layer protect them from corrosion.