MoS₂-based solid lubricants have obtained significant attention and are extensively employed in the aerospace industry due to their desirable tribological performance. However, to enhance their performance in humid environments, MoS₂ is often doped with Pb-based compounds. Considering the health and environmental concerns associated with Pb, it is necessary to develop eco-friendly alternatives. In this study, hexagonal boron nitride (hBN) has been used as a potential substitute for Pb-based dopants in MoS₂-based solid lubricants and coatings with varying hBN contents (9.5, 11.5, 13.5, 15.5, and 17.5 wt.%) were applied to stainless steel substrates using a spray bonding technique. The friction and wear characteristics of the coatings were analyzed by using a ball-on-flat tribometer, employing constant load conditions. Subsequently, ex-situ analysis techniques such as scanning electron microscopy (SEM), raman spectroscopy, and atomic force microscopy (AFM) were used to characterize the coatings. The results showed that the coating with a lower hBN concentration presented improved tribological properties, which was correlated with the development of an effective MoS₂-based transfer/tribo-film. This suggests that optimizing hBN content is crucial for enhancing the lubrication performance.

Evaluation of the wear behavior of composite coatings based on Stellite 6 with additions of WC-Ni and Cr ₃ C ₂ , produced via high-velocity oxygen fuel (HVOF) spray.

This paper investigates the tribological behavior of Stellite 6 coatings produced with high-velocity oxygen fuel (HVOF), with an emphasis on the transition between severe and mild wear regimes and the glaze layer formation. The development of these coatings involved two spray parameters modifying the oxygen fuel ratio and three post-heat treatment conditions at temperatures ranging between 600 °C and 1150 °C. The coatings were tested under conditions varying the normal load, temperature, sliding distance, and testing temperatures (up to 300 °C). The results show that the coating obtained from the HVOF process exhibited a microstructure different from the conventional bulk Co-alloys, significantly impacting the wear performance. The coating post-processing was essentialto enhance wear resistance at elevated temperatures.