Computational modelling based wear resistance analysis of thick composite coatings

Abstract

A computational modelling and simulation approach was developed and applied for wear resistance analysis of composite coatings. Three new numerical finite element models were developed to include microstructural properties of typical thick thermal spray and laser cladded metal matrix coatings. The first was an ideal synthetic defect free material model, the second an advanced synthetic model containing defects and the third an image based real model. A thermal spray WC-CoCr coating and a laser cladded WC-NiCrBSi coating were characterised and the information obtained of their microstructure and properties was used for computational stress and strain simulations. The simulations were carried out for a set of indentation and scratch test contact conditions. Wear related features were validated empirically by abrasive rubber wheel testing and sliding contact pin-on-disk testing in dry conditions. Features like high local curvature, notches, abnormally large particles, thin ligament or throat-like structures of a specific material phase, clusters of interlinked carbides or high local fraction of a specific material phase had a great impact on the resulting stress state and wear resistance of the coating. The composite structures of the coatings offered a 2 to 50 times lower abrasive wear and more than four orders of magnitude lower sliding wear rate compared to the reference steel surface.