TO STUDY THE HIGH TEMPERATURE OXIDATION AND CORROSION BEHAVIOR OF SOL-GEL COATING IN COAL FIRED BOILER ENVIRONMENT

Abstract

1-ugh temperature corrosion is serious problem in incinerators, boilers, turbines and IC engines. Burning of different type of fuels produce salts like Na, V, S, and K which get deposited on boiler's parts and deteriorate the material at elevated temperatures. Coating is a generic way to enhance the material's life at elevated temperatures in presence of these salts. Sol-gel method of coating is easy and cheap as compared to thermal spray coatings. In present work Dy203 doped Si02-ZrO2 coating was deposited on Ni Based super alloy SuperNi 600 and boiler steel Grade Al ASTM SA2I0. Two materials were choose to compare high temperature corrosion resistance of sol-gel coating. Sol-gel dip coating method was used for coating the materials. Cyclic oxidation tests performed at 900°C in air and in simulated boiler environment (Na2SO4- 60%V205) were performed on Coated and Bare samples. Coated samples have shown better resistance to cyclic oxidation in air. Whereas the coating wasn't effective in presence of salts. Scanning Electron Microscope, Energy Dispersive Spectroscopy, XRay Mapping and X-sectional analysis techniques were used to analyse the corrosion products, measure the thickness of oxide layer and to measure the penetration of salts in materials.