Characterization, corrosion, adhesion and wear properties of Al2O3 and Al2O3:TiB2 composite coating on Al 7075 aluminum alloy by one-step micro-arc oxidation method

This study was carried out in order to increase the usage areas of Al 7075 alloy, which is preferred as an engineering material in the aerospace industry, defense industry and automotive industry, in high temperature applications, wear resistance in different environments and corrosion resistance in aggressive environments. For this purpose, the focus was on the growth of Al2O3 and Al2O3:TiB2 doped composite coatings on the surface of Al 7075 aluminum alloy by the MAO method, and the structural, morphological, corrosion, adhesion and wear properties of the grown coatings in three different environments (atmospheric conditions, brine containing 3.5 % NaCl and oil). Firstly, Al2O3 coatings were grown in electrolytic solution number 1. Secandly, Al2O3:TiB2 doped composite coatings were grown in electrolytic solution number 2 and the phase structure, microstructure and chemical composition of the grown coatings were determined by X-ray Diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, respectively. The abrasion behavior of the coatings in three different environments was determined by a pin-on disc abrasion tester, adhesion resistances were determined by a Scratch Test, and corrosion resistance was determined by a potentiodynamic polarization tester. It was observed that dense and uniform coatings were grown on the surfaces of TiB2 nanoparticle-added (Al2O3:TiB2) coatings, porosity and pore sizes on the surfaces of the coatings were reduced and microcracks were reduced. In addition, it was determined that the corrosion resistance and wear resistance of composite coatings (Al2O3:TiB2) grown with nanoparticle addition increased, and coatings with high bond strength with the substrate were grown.