2D MoS2-hBN hybrid coatings for enhanced corrosion resistance of solid lubricant coatings

Abstract

Molybdenum disulphide (MoS2) is commonly utilized as a solid lubricant due to its outstanding wear resistance properties. However, the application of MoS2 is restricted due to its high tendency of oxidation and corrosion when exposed to oxygen and humid air. Here, in this work, we developed a 2D hybrid structure by incorporating the 2D material, hexagonal boron nitride (hBN), with MoS2 to enhance the corrosion resistance properties. MoS2-hBN 2D hybrid coatings with varying concentrations of hBN nanosheets were deposited onto mild steel specimens to evaluate tribological and corrosion properties. The friction studies were carried out using a high-frequency reciprocating tribometer (HFRR) and found that hybrid coatings showed a slightly higher coefficient of friction (CoF) than pure MoS2 coating due to hBN addition. Electrochemical corrosion studies of the coatings were conducted in 3.5 wt% NaCl solution. Potentiodynamic polarization and electrochemical impedance spectroscopy studies depicted lower corrosion rate and higher corrosion resistance for MoS2-hBN coatings than pure MoS2 coating. The increase in hBN content resulted in an enhanced corrosion resistance. Raman spectroscopy studies of corroded coatings revealed the presence of a high concentration of MoO3 in pure MoS2 coating, while oxide peaks were nearly absent in MoS2-hBN coatings. XPS analysis depicted comparatively lower oxidation and MoO3 concentration in hybrid coating compared to pure MoS2 coating.