Parameter optimization for enhancing tribological properties of sol–gel alumina and aluminum silicate-coated aluminum alloy: Grey–Taguchi method

Abstract

The degradation of materials by wear is reduced by the wet chemical technique, where a thin film is coated over the surface susceptible to wear. The sol–gel coating method is one of the wet chemical techniques normally employed to improve tribological and anti-corrosive properties. This paper deals with evaluating tribological properties such as coefficient of friction, volumetric wear loss, and corrosive stability of alumina and aluminum silicate-coated aluminum alloy A356. The coating parameters affecting the tribological properties are identified and the experiments are designed using Taguchi orthogonal array and optimized using the Grey relation analysis technique. The tribological characteristics at room temperature are evaluated using a pin on disc tribometer. Among the sol–gel coating parameters chosen for minimizing the effect of wear and coefficient of friction between surfaces, the temperature for heat treatment and pH of the sol–gel are identified as the critical parameters that affect the tribological characteristics. The corrosive stability of the samples has been evaluated by corrosion current, corrosion potential, and corrosive stability methods. It is found that tribological properties and corrosive stability are improved for the coated sample compared with the uncoated sample. It is also observed that alumina coating provides better tribological properties and aluminum silicate coating provides better corrosive stability.