Effect of nano-particles ZnO and layered GO on high temperature tribological performance of MoS₂-based heterojunction composite lubricating coating

As an excellent solid lubricant in vacuum and inert gas environment, molybdenum disulfide (MoS₂) is easy to be oxidized in high temperature, which leads to serious deterioration or even failure of lubricating performance. The introduction of doped phase or composite can improve the high temperature lubricating performance of MoS₂-based lubricating coating to some extent. In this work, the effect of nano-particles zinc oxide (ZnO) and layered graphene oxide (GO) on the high temperature (400, 450 and 500 °C) tribological properties of MoS₂-based composite lubricating coatings were studied. It was found that the tribological performance of MoS₂-ZnO composite coating were the best for almost all test conditions, and the average friction coefficient and wear rate were about 0.25 ~ 0.27 and 4 ~ 6 × 10⁻⁵ mm³/Nm, respectively. The promising tribological performance of MoS₂-ZnO composite coating was attributed to the ZnO that mitigated the oxidation of MoS₂, and the formation of ZnS. It is the formed ZnS, nano-ZnO and a small amount of MoS₂ that provided synergistic lubrication. However, the introduction of layered GO deteriorated the tribological properties of the MoS₂-based composite coating, due to the high-temperature decomposition of GO and the formation of hard abrasive particles. The results can provide reference for the design and preparation of MoS₂-based composite lubricating coating. Graphical abstract: (Figure presented.)