Tribotechnical Properties of Ceramic Antifriction Coatings Based on Iron Oxide and Boron Oxide

Abstract

The work is devoted to the study of the tribological properties of functional coatings based on the FeO oxide matrix, additionally doped with boron oxide B₂O₃ and zirconium dioxide ZrO₂. The coatings are obtained by highly concentrated short-pulse laser processing of powder compositions previously applied to metal surfaces. The resulting coatings are subject to wear tests under conditions of dry sliding friction with fixation of the friction coefficient, depending on the applied load and the composition of the powder composition. The results give an idea of the degree of change in the coefficient of friction of coatings depending on the powder compositions, as well as their alloying. It has been confirmed that additional alloying with boron oxide has a positive effect on the tribological performance of the coating; in particular, the introduction of 4% boron oxide reduces the coefficient of dry sliding friction to a unique 0.09–0.10. At the same time, a more stable scuffing resistance of friction surfaces is observed, confirmed by studies of surface roughness after testing. A feature of the tribological behavior of the coatings under study is the excessively high temperature background of the tests, reaching 300°C. High temperature and the presence of oxide structures are a catalyst for the formation of stable tribological structures between the rubbing surfaces. The nature of the tribostructures is self-organizing in a “glaze” type and has the property of recovery under friction conditions. After the formation of tribostructures in the friction zone, a significant decrease in temperature and an abrupt decrease in the friction coefficient are observed. With an increase in the amount of boron oxide, the friction coefficient does not decrease so significantly and the minimum value of the dry friction coefficient corresponds to 0.14–0.15, which is caused by a decrease in the cohesive strength of the coating.