Analytical, numerical and experimental studies on ploughing behaviour in soft metallic coatings

A coating layer is often present on engineering surfaces. An example is a zinc coating on steel sheet, this being a soft metallic coating on a hard substrate. To characterize the tribological behaviour of these engineered surfaces, it is necessary to understand the mechanical behaviour of the coating during ploughing. The material point method (MPM)-based ploughing model has been used to compute friction and the ploughed profile when an asperity is ploughing through a coated surface. An analytical ploughing model has also been used to study the effect of the thickness and hardness of the coating relative to the substrate on coefficient of friction using rigid-plastic material behaviour and its results have been compared with the MPM-model results. The MPM-based ploughing model has been experimentally validated and is shown to agree well with the ploughing experiments using rigid spherical indenters sliding through lubricated-zinc coated steel, uncoated steel and bulk zinc over a range of applied loads.