A crystal chemical approach to the formulation of self-lubricating nanocomposite coatings

In recent years, design or formulation of superhard coatings with self-lubricating properties has become one of the hottest research topics in the field of tribological coatings. In particular, the production of new coating architectures based on nano-composite or -layered morphologies has become very popular, especially for dry machining or high-temperature sliding bearing applications. In such applications, these coatings can lead to the formation of self-lubricating tribofilms that reduce friction and wear. In this paper, a crystal chemical model is presented to account for the formation of such low-shear and hence low-friction tribofilms. In support of this model, recent experimental findings of various research groups are also provided. The major benefit of this model is that it may provide a scientific means to better design and formulate future tribological coatings that provide not only superior wear resistance but also sufficient lubricity during dry machining or sliding applications.