Evaluation of adhesion and erosion/corrosion resistance of nano-composite and nano-multilayer thin films in molten aluminum alloy

Die casting as a well-known manufacturing method to produce high precision aluminum parts, encounters die failure. The most important wear and failure mode of die casting process is washout damage on working die surfaces attributed to erosion, corrosion, and soldering. Washout caused by a thermo-chemical interaction between aggressive aluminum melt and die steel on the surface. The influence of TiAlN–Si3N4 nanocomposite and TiAlN/TiN nano-multilayer thin film coatings on washout resistance of H-13 tool steel was evaluated in A384 aluminum alloy melt. Thin films were applied by physical vapor deposition using cathodic arc evaporation technique onto pre-nitrided pin-shape samples at 350 °C. X-ray analysis was employed to assess films constitutive phases. Scanning electron microscopy (SEM) investigation and atomic force microscopy approach were employed to indicate surface morphology and roughness of nano-structural coatings. An accelerated immersion test was conducted to compare washout resistance of coated samples by immersion them in aluminum alloy melt for periods of 30, 60, 90, and 120 min at 680 °C. Furthermore, specially developed release test was done to measure wettability and adhesion tendency of samples. SEM investigation of corroded and eroded surface showed some pitting effect on coatings and tribo‐chemical interaction inside the pits between aluminum melt and substrate. Nano-structural coatings not only prevented intermetallic phase formation at the surface but also reduced the erosion/corrosion rate which is known as cause for the washout.