Thermal stress analysis and structural optimization of DLC/tiAlN composite coatings

Abstract

Residual thermal stresses from Physical Vapor Deposition (PVD) trigger premature delamination in DLC/TiAlN coatings by weakening interfacial adhesion. To improve coating reliability, this study establishes a thermo-mechanically coupled finite element framework to quantify how deposition temperature and film thickness dictate stress evolution. Simulation results demonstrate that a 150 °C deposition temperature and a 3 μm TiAlN interlayer synergistically reduce interfacial shear stress by 42%. Experimental validation confirms an optimized wear depth of 2.9 ± 0.3 μm and a 68% increase in critical load (Lc). The optimized architecture triggers a transition from brittle fracture to ductile-dominated failure, providing a quantitative “low-stress, high-toughness” design paradigm for DLC-based composite coatings.