The properties of oxide-ceramic layers with Cu and Ni inclusions synthesizing by PEO method on top of the gas-spraying coatings on aluminium alloys

Abstract

Based on thermodynamic calculations, the possible options for forming of oxide-ceramic layers (Al2O3) alloyed with copper and nickel inclusions have been considered. For this purpose, plasma-electrolyte oxidation (PEO) of the directly aluminum alloys surfaces or the gas-thermal coatings sprayed on top of them was used. A sequence of reactions occurring in plasma channels during PEO is proposed. Experimental verification of the obtained oxide-ceramic layers was carried out at the different types of tests. All analyzed oxide-ceramic layers were characterized by high elasticity modulus, hardness and wear resistance. A selective mass transfer effect was detected during friction of the oxide-ceramic layers (alloyed with dispersed copper inclusions) with cast-iron in the boundary lubrication conditions in the motor oil with glycerine addition. The glycerate films of iron and copper were formed during friction process on the surfaces of friction elements. As a result of the friction ratios and the wear resistance of such friction pairs was reduced by an order of magnitude. However, most importantly, the low values in friction coefficient were maintained even at high specific loads.