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

Abstract

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 Al 2 TiO 5 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.

Preparation of a Ni-P-nanoPTFE Composite Coating on the Surface of GCr15 Steel for Spinning Rings via a Defoamer and Transition Layer and Its Wear and Corrosion Resistance

“…Many researchers have successfully prepared Ni-P-nanoPTFE composite coatings on metals and nonmetals and studied the effects of plating solution components, process parameters, dispersion methods, and PTFE content on the wear and corrosion resistance of the coatings [ 19 , 20 , 21 ]. The recent research mainly focuses on the performance of combining Ni-P-nanoPTFE composite coatings with other coatings [ 22 ] or how to increase the PTFE particle content in Ni-P-nanoPTFE composite coatings on substrates in a short time [ 23 ]; however, the research on how to ensure the uniform dispersion of nano-PTFE particles in Ni-P-nanoPTFE composite coatings and reduce the occurrence of missing plating is not perfect. Relevant studies have shown that the combination of an appropriate amount of cationic surfactants and fluorocarbon nonionic surfactants can significantly improve the dispersion of nano-PTFE particles in the solution [ 24 , 25 , 26 ], but this will increase the foaming properties of the plating solution.…”

Characterization and Tribological Behavior of Electroless-Deposited Ni-P-PTFE Films on NBR Substrates for Dynamic Contact Applications

“…However, ceramic particles were avoided since they may wear the material in contact with rubber, compromising the sealing, and PTFE was chosen among the solid lubricants. PTFE is a low friction and corrosion resistant polymer [14,16,17], known for being self-lubricant [18] and its co-deposition with Ni-P has been shown to significantly decrease the wear rate and CoF of metallic substrates [19][20][21][22][23]. However, as far as the authors are aware, Ni-P-PTFE composite coatings have not been investigated for the protection of non-metallic surfaces, particularly rubber surfaces.…”