Solid lubrication performance of sandwich Ti3C2Tx-MoS2 composite coatings

In recent years, research effort has been dedicated towards the exploration of MXenes' solid lubrication per-formance verifying an outstanding wear performance due to the formation of beneficial tribo-films. However, the resulting coefficient of friction of these coatings is rather high thus asking for further optimization. To tackle this short-coming, we designed sandwich Ti3C2Tx/MoS2 composite coatings with the overall goal to combine low -friction (MoS2) with high wear resistance (Ti3C2Tx). The tribological performance of these sandwich compos-ites having different stacking sequences (Ti3C2Tx/MoS2 vs. MoS2/Ti3C2Tx) was compared with the behavior of their individual components separately using ball-on-disk tribometry under dry sliding conditions as a function of the applied normal load (contact pressure). Based on our results, sandwich-like composite coatings led to a superior tribological performance thus reducing friction and wear by about 50 %. Regarding the stacking sequence, the Ti3C2Tx/MoS2 sandwich coating showed the best friction and wear characteristics. The obtained experimental tendencies imply that the formation of a beneficial tribo-layer enhances the chemical stability (extraordinary resistance) and reduces friction compared to each pure materials, making them ideal candidates to improve the tribological performance of mechanical components subjected to elevated contact pressures.