Plasma Spray Coating of Red Mud on Metals

Abstract

Red mud, the gangue produced during alumina extraction, has become a major issue for disposal. In recent years, trials are made/in progress for utilization of this waste/byproduct in some meaningful applications. In the present investigation, efforts are made to use red mud for developing plasma spray coatings (ceramic/cermet) on metal substrates. The raw material used in this study was collected from NALCO, Damonjodi, Orissa. The red mud was sieved for selection of particle size and an average size of 100-150 micron was found to be suitable for spraying purpose. Thermal spray coatings are deposited on various metal substrates viz. S.S., M.S., Cu & Al at different operating power levels (between 6 to 17.5 kW) of the plasma torch. The mechanical aspect such as coating adherence strength & hardness are measured. The maximum adherence strength of ~8 MPa is noted for the coating deposited on Cu substrate. The surface & interface morphology was studied through SEM. It is found that, red mud can be used to deposit ceramic coatings which may be useful for tribological applications