Thermal Spray Coating of Redmud on Metals

Abstract

Red mud emerges as the major waste material during production of alumina from bauxite by the Bayer’s process. It comprises of oxides of iron, titanium, aluminium and silica along with some other minor constituents. The present investigation explores the coating potential of this industrial waste. It envisages the processing and characterization of a series of plasma sprayed coatings made with red mud and red mud pre-mixed with different proportions of fly ash and powders of aluminium and carbon. These materials do not belong to the so called “plasma sprayable” category. They have been deposited on aluminium, copper, mild steel and stainless steel substrates by atmospheric plasma spraying. The coatings are characterized to evaluate their potential as wear resistant coatings. Micro-structural characterization of the coatings has been carried out using scanning electron microscopy, x -ray diffraction and image analysis technique. It is found that red mud is eminently coatable. The coating...