Synthesis and Characterization of Scratch-Resistant Ni-P-Ti-Based Composite Coating

In order to improve the toughness of Ni-P coatings, Ti particles were introduced into the plating solution to produce a Ni-P-Ti composite coating (on API-X100 steel), which was subsequently annealed to form superelastic NiTi precipitates within the coating. The effect of Ti content on deposition rate and surface morphology of Ni-P-Ti coatings was studied. A detailed investigation of the influence of Ti content and annealing on the microstructure, microhardness, and scratch behavior of Ni-P-Ti composite coatings was carried out. Further, scratch resistance and toughening mechanisms, namely, crack deflection, crack bridging, and crack shielding, are discussed. The NiTi precipitates greatly improved the cracking and scratch resistance as a result of the superelastic NiTi toughening effect.This publication was made possible by NPRP Grant #NPRP8-1212-2-499 from the Qatar National Research Fund (a member of Qatar Foundation).Scopu