Corrosion characterization of Al 6061 / Red Mud MMCs in hydrochloric Acid

Abstract

Abstract Composites materials are in demand now a day due to their decreased weight and improved properties with respect to mechanical behaviour. They also exhibit increased corrosion resistance in acid, salt and alkali mediums. In this paper experiments related to the corrosion properties of composites made up of Aluminium 6061 reinforced with red mud particulates. Both matrix and reinforcement are available commercially. Matrix Alluminium 6061 alloy is an important alloy used in many applications. When aluminium is removed from bauxite ore the waste obtained is red mud.. It is found to contain the oxides of iron, silicon, aluminium, zirconium, titanium and vanadium. Composites are manufactured by creating a vortex in the molten aluminium alloy. Vortex is created by introducing an impeller after heating matrix to its melting point. Red mud particulates without any coating are subjected to preheating and poured to the vortex, entrapped gas bubbles are removed by adding hexa chloro ethane tablets. Then after stirring the mixture is poured in to cast iron moulds which are pre heated. Composites containing three different weight percentage of red mud reinforcement. For comparison matrix alloy was also casted. Cylindrical specimen and rectangular specimen were machined form all the composites and matrix alloy according to ASTM standards. The composites were characterized with respect to weight loss and polarization test in hydrochloric acid. Both the tests were conducted according to ASTM standards. Electro chemical work station was used to conduct the potentiodynamic polarization test. Corrosion resistance of composites were found to be increased in the tests more than the matrix alloy. Therefore composites are preferred instead of matrix alloy in all the applications