INFLUENCE OF THE SUBSTRATE MATERIAL ON THE FORMATION AND PROPERTIES OF MICRO-ARC COATINGS WITH PARTICLES OF beta-TRICALCIUM PHOSPHATE

The regularities of formation of coatings with the particles of beta-tricakium phosphate (beta-TCP) by micro-arc oxidation method on the metal substrates of Ti, Ti-40Nb, and Mg0.8Ca alloys were studied. The effect of the electrophysical properties of the transitional oxide layer on the structural-morphological and adhesive properties of the coatings was established. The small values of the band gap and the high dielectric constants of TiO2 and Nb2O5 oxides contributed to the transmission of cascades of micro-arc discharges with a low intensity. In this case, MgO oxide with a low dielectric constant accumulated a large amount of electrical energy, which was released in the form of powerful discharges. Coatings on the Mg0.8Ca alloy were characterized by high thickness and roughness, contained the largest amount of the crystalline phase, and had good adhesive properties. The maximum critical load value of 17 N was noted for the coating on the Mg0.8Ca alloy, and the minimum value of 7 N was observed for the coating on the Ti-40Nb alloy.