Abstract
In the field of surface engineering, the use of self-lubricous coatings with the incorporation of vanadium represent a promising approach to reduce friction, thus contributing to the wear behavior. For vanadium containing hard coatings produced by means of thin film technology, the reduction in friction at elevated temperatures was repeatedly attributed to temperature-induced and tribo-oxidatively formed oxides which act as solid lubricant. Only very few studies focused on the tribological characteristics of vanadium containing arc sprayed coatings. In this study, the tribological characteristics of a vanadium containing iron-based arc sprayed deposit were investigated in dry sliding experiments under ambient conditions and different temperatures. Types of wear at the worn surfaces and counterparts were examined by means of electron microscopy and energy dispersive X-ray (EDX) spectroscopy. The speciation of vanadium in the superficial layer was determined using X-ray absorption near edge structure (XANES) spectroscopy. It was found that the vanadium-containing coating exhibited a distinctly reduction of the coefficient of friction above 450 °C which further decreased with increasing temperature. XANES spectroscopy indicated an increased oxidation state for the V component on the coating surface, suggesting the prevalence of specific vanadium oxides which promote a self-lubricating ability of the coating.
Highlights
Tribo-oxidation was validated for practical applications as a favorite mechanism for the development of dry running tribosystems [1]
The findings indicate a distinct reduced coefficient of friction (COF) for the Fe-V coating above 550 ◦ C, especially at 750 ◦ C
We investigate the correlation between the normalized peak area and the pre-edge centroid position of the treated Fe-V coatings as well as ofpre-edge the vanadium oxides the pre-edge centroid position of the treated coatings as well as of the vanadium oxides
Summary
Tribo-oxidation was validated for practical applications as a favorite mechanism for the development of dry running tribosystems [1]. Self-lubricious hard coatings evolved into a promising candidate to provide an improved friction behavior, which in turn contributes to the wear resistance [2]. In the field of thin film technology, a reduction in friction has been achieved, among others, by using V-containing coatings [3]. For V-containing coatings, temperature-induced and tribo-oxidatively formed, low shear strength oxides act as solid lubricants, determining the lubricating capacity of functional surfaces. The participation of V forms oxides of the homologous series. Vn O2n−1 with 3 < n < 10 between the end members V2 O and VO2 , and are so-called Magnéli phases [4,5].
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