Effect of Microstructure on Thermoelastic Stresses in Al2O3/Ti(C,N,O)/Ti(C,N) Coating Systems Studied by Finite Element Method Simulations

Abstract

Finite Element Method (FEM) simulations were performed to qualitatively study the effects of texture anisotropy, bonding interlayer thickness, and average crack spacing on the evolution of thermoelastic stress in coatings systems containing Al2O3 and Ti(C,N) layers bonded with a Ti(C,N,O) interlayer. Commercial WC-6wt.%Co tools were considered as substrates, including a superficial ?-phase rich layer. Significant stress differences are observed between the Al2O3 and Ti(C,N) layers due to differences in the Coefficient of Thermal Expansion (CTE) relative to the substrate. No significant differences were observed when considering axis-dependent CTE and elastic data of the Al2O3 layer, nor introducing a Ti(C,N,O) interlayer. Cracks across the coatings resulted in a significant reduction of stress in both layers, reaching values near zero in the cracks’ vicinity, this effect being more prominent the shorter the crack distances. Differences among our FEM simulations and experimental residual stress reports on similar systems highlight the need to develop more complex models to understand the effect of nucleation processes and microstructure on the residual stress.