Evaluation of arc sprayed coatings for erosion protection of tubes in atmospheric fluidised bed combustion (AFBC) boilers

Improvement in cored wire composition and fabrication has made possible the application of wear resistant coatings using the attractive twin wire arc thermal spray technique. In the present work, different wear resistant coatings named Alpha 1800, Armacor M and Ducor were deposited using TAFA 9000 wire arc spray equipment for their application in atmospheric fluidized bed combustion boilers. The erosion behaviour of these coatings was evaluated in a test rig and compared with that of carbon steel. Evaluation of coatings up to 600 °C indicated that the lowest erosion rates were observed for Alpha 1800 coating, the erosion rate of this coating being 5–10 times lesser than steel base depending upon the test temperature and erodent impact angle. Therefore, Alpha 1800 coating was sprayed on the superheater coils of an AFBC power plant.