MXene Coatings Based on Electrophoretic Deposition for the High-Temperature Friction Reduction of Graphite for Mechanical Seal Pairs

This paper presents the tribological properties of MXene (Ti3C2Tx) coatings on the surface of impregnated zinc phosphate graphite. MXene coatings were deposited on the surface of the impregnated zinc phosphate graphite by the electrophoretic deposition method at different voltages of 5 V, 10 V, and 15 V. The tribological properties of the MXene coatings were investigated from room temperature to 400 °C in ambient air. The results show that MXene coatings are helpful to improve the tribological properties of the impregnated zinc phosphate graphite at elevated temperatures. The coatings deposited at 5 V have the best anti-friction behaviors among the coatings at the different deposition voltages, which indicates that the MXene coatings deposited at 5 V are suitable for applications in a wide range of temperatures, especially high-temperature environments. The average CoF of the coatings deposited at 5 V is about 0.18 at 200 °C, 0.25 at 300 °C, and 0.21 at 400 °C, respectively. The CoF of the coatings deposited at 15 V is relatively stable with the increase in temperature. Moreover, the high-temperature low-friction mechanism was discussed. The high-temperature low-friction mechanism is attributed to the good self-lubricating behaviors of the impregnated zinc phosphate graphite and the transfer film of the MXene coatings.