Adhesive strength and physical, mechanical, and triboengineering properties of nano- and microstructural Al2O3 coatings

The methods of atom-force microscopy and measurement of the nanohardness, elasticity modulus, cohesion forces, and friction coefficient with scratch testing (the scratching method) are applied to study the Al2O3 oxide coatings produced by magnetron deposition on Al targets. The morphologies of the coatings are compared when they are produced by the reactive synthesis and magnetron target sputtering and application of oxygen ions in high-frequency plasma. The accomplished study of the tribological and mechanical characteristics demonstrates that the resulting coatings possess stronger hardness and elasticity modulus. Application of the oxide coatings reduces the friction coefficient considerably compared with the substrate; the scratch test reveals higher strength and better adhesion to the substrate. Comparative analysis shows that the Al2O3 coatings applied to the nanostructural TiN film are 1.5 times harder than the coatings deposited on steel.