High-temperature corrosion behavior of bare and NiCr-coated AISI 422 steel by varying the coating thickness in the Na2SO4 + 60%V2O5 environment

Abstract

It is difficult to assess fatalities due to high temperature corrosion, such as plant closure time, production loss, decrease in productivity, contamination, etc. In this context, the AISI 422 martensitic steel is a popular choice for high temperature applications due to its unique properties. The durability of this material can be increased by coating technology. The Ni-20Cr composite powder is a highly recommended choice for high-temperature applications. In this research, Ni-20Cr coating was sprayed on AISI 422 steel, using a flame spray process with two different thicknesses of 250–350 µm and 350–450 µm. Corrosion studies have been carried out at temperatures of 600 °C and 900 °C for Na2SO4 + 60%V2O5 salt solution environment. The corrosion kinetics were studied with the help of the Wagner equation. Micrographics analysis has been performed by Scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) technique. Coated material has been shown better corrosion resistance compared to bare. The low-thickness coating has better corrosion resistance corresponding to both bare and high-thickness.