Morphology and Wear Behavior of Monolayer TiAlN and Composite AlCrN/TiAlN-Coated Plasma-Nitrided DAC-10 Tool Steel

This experimental study focuses on the comparison of a monolayer of titanium-aluminum-nitride (TiAlN) and a composite of AlCrN/TiAlN coating where aluminum-chromium-nitride (AlCrN) deposited as an interlayer. These coatings have been deposited over heat-treated and plasma-nitrided DAC-10 tool steel using the physical vapor deposition (PVD) technique. Under this study, surface morphology, structural, nanomechanical, and wear behavior of these coated surfaces have been compared. Results suggest that surface roughness of bare nitrided DAC-10 tool steel decreased drastically and nanomechanical properties improved significantly upon coating. AlCrN/TiAlN coating exhibits a high strain hardening exponent (n) value which indicates lower maximum penetration depth and pile-up formation during nanoindentation, it also validates that AlCrN/TiAlN-coated surface comprises high hardness. The wear mechanisms of both the surfaces have been observed under FE-SEM with EDS; it reveals that severe adhesion of SAPH370 steel ball and heavy oxidation on both the coated surface. Even so, with high average arithmetic mean height and nanomechanical properties, AlCrN/TiAlN-coated surface performed better under nanoindentation and tribological test and it also reveals a lower wear rate under dry sliding conditions.