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The aim of our study is to evaluate the tribo-corrosion properties of conversion coatings on Vanadis 6 type of steel. Vanadis 6 cold work steel is a high-carbon, high alloyed steel known for its favourable mechanical properties even in very harsh operating conditions, including high loads, contact stresses, contact temperatures and severe wear [1]. Mechanical properties were recently reported to be improved by cryogenic treatment [2], while corrosion properties were reported to be improved by hard coatings [3].
In this study, two types of hard coatings, namely boron and Niobium coatings, were applaid to the Vanadis 6 substrate. These coatings improve the mechanical as well as corrosion properties of the Vanadis 6 steel substrate. Tribocorrosion properties were studied using reciprocating sliding in different solutions. The tested solutions were 0.1 M NaCl and 0.0001 M NaOH, pH 13, and were then suited to better estimate tribocorrosion properties of tested materials. Different characterization methods were employed, including optical microscopy, SEM/EDS investigation of the worn surfaces, Raman spectroscopy, profilometry and Vickers hardness tester.
Tribocorrosion of passive materials such as stainless steels or titanium alloys has been widely studied during the last decades under different mechanical and electrochemical conditions in a wide range of corrosive electrolytes. Tribocorrosion of non-passivating or active materials is subjected to progressive dissolution [4]. In this study, a multi-step investigation and iterative refinement of the experimental approach was used to obtain representative data, in order to estimate the contributions of mechanical wear, corrosion, and tribocorrosion to total wear.