Corrosive and tribocorrosive behavior of plasma powder coatings

Abstract

Purpose. To investigate corrosion and tribocorrosion characteristics of plasma-powder coatings on the basis of iron, nickel and Fe-Ni system in the envyronments containing chlorides, hydrogen sulfide and ammonia. Metodology: corrosive-electrochemical, tribological, metallographic methods have been used.Results It was established that as the pH of the solution increases, the corrosion resistance of the coatings increases. The highest corrosion resistance has a surfaced layer based on nickel 06Х17Н80С3Р3, however, under tribocorrosion conditions, fragile component of coatings form an abrasive in the friction zone that intensifies the destruction. Compared to others, the coating 06Х17Н80С3Р3 has the lowest resistance to corrosion-mechanical destruction.The fragile component is absent in layers, deposited from powders 01H17N8S6G and 08Х17Н35С3Р. The solid phases are uniformly distributed in a plastic matrix corresponding to the Sharpi-Bochvar rule. In this coatings, the contact interaction occurs in the absence of abrasive wear, which explains the high resistance to tribocorrosion.It is possible to qualitatively evaluate the processes of formation and destruction of secondary structures in the friction zone of tribocorrosion by comparing of the corrosion potentials, tribocorrosion potentials and passivation potentials. Additional information may be provided by the level of local oscillations of the tribopotential, which characterizes the repassivation rate.Practical result. A new composition 08Х17Н35С3Р3 for plasma-powder coatings has been proposed to increase the wear and corrosion resistance of steel surface.