Electroless Ni–P–TiO₂ Nanocomposite Coatings for Enhanced Durability and Saltwater Corrosion Protection of Jet Ski Engine Components

Jet ski engine components operate in aggressive marine environments where prolonged saltwater exposure accelerates corrosion and mechanical degradation, leading to reduced service life and high maintenance costs. This study investigates the development and performance of electroless (Nickel - Phosphorus - Titanium oxide) Ni–P–TiO₂ nanocomposite coatings as a protective surface modification for mild steel components. The coatings were produced using an optimized electroless plating bath incorporating nano-sized TiO₂ particles into the Ni–P matrix to refine grain structure, reduce porosity, and enhance passive film stability. Surface morphology and composition were examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), while phase structure was analyzed via X-ray diffraction (XRD). Mechanical performance was evaluated through microhardness testing, and corrosion resistance was assessed using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 3.5 wt% % NaCl solution to simulate saltwater exposure. The incorporation of TiO₂ nanoparticles produced a dense, uniform coating with improved adhesion to the mild steel substrate. EIS measurements indicated significantly higher polarization resistance, confirming superior long-term corrosion protection. These improvements are attributed to the barrier effect of well-dispersed TiO₂ nanoparticles, which impede chloride ion ingress and stabilize the passive layer. The results highlight that electroless Ni–P–TiO₂ nanocomposite coatings present a cost-effective and high-performance strategy for extending the operational life of mild steel jet ski engine components in harsh saltwater environments.