Influence of deposition temperature on the microstructure, wear and corrosion behaviour of AlTiN/AlTiCrN ceramic coatings on A8 tool steel

Deposition temperature is a known pivotal process parameter influencing the tribological and corrosion performance of physical vapour deposited ceramic coatings. Yet, the impact of the parameter remains highly system-specific, limiting generalization of observed trends across different coating-substrate systems. Therefore, this study investigates the effect of deposition temperature (350 – 450 °C; designated as T350 – T450) on the microstructural evolution, mechanical properties, wear, and corrosion behaviour of AlTiN/AlTiCrN coatings deposited on AISI A8 tool steel for woodworking applications. Coatings were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, nanoindentation, scratch testing, ASTM G65 abrasive wear testing, and electrochemical analysis. Results showed that T350 exhibited the lowest wear rate (∼2 × 10−4 mm3/Nm); 36 and 56 % lower than T400 and T450, respectively. This superior wear resistance was attributed to its higher adhesion (critical load ∼ 11 N), thicker coating (2.8 μm), smoother surface (R_a = 0.25 μm), and higher H/E ratio (0.072), despite an intermediate hardness (31 GPa). Although maximum hardness (36 GPa) occurred at T400 due to finer crystallite (∼10.4 nm) and elevated microstrain (0.77 %), its higher macroparticle density (0.18 particle/μm2) and roughness (R_a = 0.31 μm) compromised performance. Additionally, corrosion resistance was superior at T350 and T450 (protective efficiency >45 % and porosity <0.70 %), attributed to denser structures, thicker coatings, coarser crystallites, and higher chromium content. Overall, these findings demonstrate that a deposition temperature of 350 °C provides an optimal balance of wear and corrosion resistance in AlTiN/AlTiCrN-coated A8 tool steels, offering valuable insights for tailoring PVD process parameters for woodworking applications.