Nanoindentation Studies of Al2O3-TiO2 Coating with NiAl Interlayer Deposited on AlSi7Mg Alloy Casting

Abstract

  The paper presents the results of material properties investigations (nanoindentation test) of an Al2O3-TiO2 coating with a NiAl interlayer, deposited by the APS (Atmospheric Plasma Spraying) method on an AlSi7Mg alloy casting. The scope of research included the analysis of the microstructure and chemical composition of the substrate material, powders, and coatings, substrate surface preparation, coating fabrication, and the analysis of nanoindentation test results, determined according to the Oliver-Pharr method. The analysis of the nanoindentation test results indicates significantly higher values of material properties, including hardness and elastic modulus, for the Al2O3-TiO2 coating and the NiAl interlayer compared to the AlSi7Mg alloy substrate, with a gradual increase in properties observed from the substrate toward the auter ceramic layer. The obtained results confirm the possibility of using the Al2O3-TiO2 coating as TBC – Thermal Barrier Coatings to improve the operational durability of internal combustion engine components made of Al-Si alloy.