EROSION. CORROSION STUDIES ON THE STELLITE COATED BOILER PIPES

Abstract

The present study has been done on high temperature Fe,- based alloy uncoated and coated with stellite. The study has been done in salt mixture containing 40% Na2SO4 and 60% V205 environment and in air. The erosion study has also been done on the same alloy with or without stellite coating. It has been found that stellite coating specimen shows more resistance to the salt environment as well as in air. The corroded specimens were studied by SEM, XRD, EPMA. The prominent phases present in case of specimen without stellite coating were Pe02i Fe203, FeS, NaFeO2 and a- MnS, while in case of specimens with stellite coating Fe203 has been mainly identified. In air environment the performance of stellitc coating specimen is superior to the specimen without stellite coating. The erosion study shows that the weight loss of stellite coated specimen decreases with time while weight loss in specimen without stellite coating increase with increase in time of exposure. Pits are observed in specimen without stellite coating whereas the specimen with stellite coating showed good surface finish as original without indication of pitting.