Electroless Plating of Ni-P and Ni-P-PTFE on Micro-Arc Oxidation Coatings for Improved Tribological Performance

Although micro-arc oxidation (MAO) coatings are widely used for anti-wear protection of metals, they usually contain lots of pores and exhibit high coefficient of friction. In this work, porous MAO coatings consisting of Al₂TiO₅ were fabricated on the titanium substrate, and then Ni-P and Ni-P-polytetrafluoroethylene (PTFE) were deposited via electroless plating to fill MAO pores and improve the tribological performance. Electroless deposited Ni-P has high wear resistance and the incorporated PTFE particles have self-lubricating property. Results show that the micro-pores of the MAO coating were completely filled by deposited Ni-P and Ni-P-PTFE, and the self-lubricating PTFE particles distributed uniformly in the coating. For the MAO-Ni-P-PTFE coating, the MAO and Ni-P components mechanically interlocked and played a load-carrying role during the tribological test, and the dispersed PTFE particles produced low friction. Compared with the MAO and MAO-Ni-P coatings, the MAO-Ni-P-PTFE coating exhibited much lower coefficient of friction and wear rate.

Keywords:
Micro-arc oxidation; electroless plating; Ni-P; PTFE; tribological performance