Holovchuk M. Influence of the diameter of high-alloyed powder wires on the structure and physicо-mechanical properties of electric-arc coatings

The work is devoted to the establishment of the regularities of the formation of arc-spraying coatings with using cored wires (CW) of the basic system Fe-Cr-B-C of different diameters (respectively, with different contents of alloying elements in their charge) to increase their wear resistance and corrosion resistance in neutral aqueous media. It was revealed that in the structure of coatings obtained by spraying CW with a diameter of 2.4 mm (with a higher filling of their shells with powder mixtures), the thickness of the lamellae, the content of oxide phases, porosity, microhardness and abrasive wear resistance were increased by 1.5-2 times in comparison with coatings formed from CW, 1.6 mm in diameter (with less filling of their shells with powder mixtures). It has been established that the corrosion resistance of coatings formed by spraying of the developed CWs correlates with the coefficient of their microheterogeneity in terms of the chromium content inside separate lamellas: the lower the microheterogeneity coefficient and the higher the chromium content in each of the lamellas, the higher the corrosion resistance of the coatings as a whole. It was revealed that on the surfaces of coatings formed by spraying the designed CWs, sulfide compounds were formed during testing for friction in hydrogen sulfide-containing environments, which reduced the adhesive component of contact interaction and served as a solid lubricant. Due to these compounds, the friction coefficient of the coatings decreased and their wear resistance increased. The tightly bounded films were formed on the surface of the coatings during their tests in ammonia-containing aqueous environment which slowed down corrosion processes but increased the coefficient of friction. In a free aerated 3% aqueous solution of NaCl, the products of corrosion wear of the coatings were weakly bound to their surface. Therefore, the tribocorrosion resistance of such coatings was low.