Finite element and experimental investigation of multiple solid particle erosion on Ti-6Al-4V titanium alloy coated by multilayer wear-resistant coating

In order to achieve an optimum design of wear-resistant coatings, it is necessary to conduct an efficient approach for determining appropriate protective coating architecture under various erosion conditions. This paper aims to investigate the multiple solid particle erosion failure of uncoated and coated Ti-6Al-4V alloy. To minimize the computational costs and time, this study presents a three-dimensional finite element model using representative volume element (RVE) technique for simulation of multiple solid particles impact. Johnson-Cook ductile damage and plasticity constitutive equations are used to describe high strain rate erosive behavior of Ti-6Al-4V. After verification of the present FE model, based on this model, the best architecture of Titanium-Nitride (TiN) based coatings deposited on Ti-6Al-4V alloy is numerically determined. At first, characteristics of the best monolayer TiN coating are obtained to use as a reference for multilayer configurations. Then, effects of thickness, Young's modulus and TiAlN layers on erosion resistance of the coatings are studied to optimize architecture of multilayer coatings. Finally, the optimized coating is deposited on Ti-6Al-4V alloy by physical vapor deposition (PVD) process and erosion behavior of coated and uncoated alloy is experimentally studied. Numerical results show that TiN/TiAlN coating is the best erosion-resistant coating compared to the other configurations of this study. It is made of a TiAlN bottom layer with 90% relative thickness and Young's modulus of 526 GPa and a TiN top layer with 10% relative thickness and Young's modulus of 300 GPa. An average 2.7 times improvement is experimentally obtained in relative erosion resistance for the coated alloy compared to the uncoated one.