Preparation and property of sol-enhanced Ni–B–TiO₂ nano-composite coatings

Ni–B–TiO₂ nano-composite coatings were fabricated on mild steel by using a novel sol-enhanced method. It was found that highly dispersed Ni–B–TiO₂ nano-composite coatings can be directly in-situ electrodeposited by adding a small quantity of TiO₂ sol solution and (DMAB) into the basic watts solution. The mechanical property of sol-enhanced Ni–B–TiO₂ coatings was significantly improved compared with that of Ni and Ni–B coatings. The microhardness of the sol-enhanced Ni–B–12.5 mL/L TiO₂ coating was ∼1061 HV₂₀₀ compared to ∼677 HV₂₀₀ of Ni–B coating and ∼350 HV₂₀₀ of Ni coating. Meanwhile, the wear resistance has also been improved remarkably. The corrosion resistance of sol-enhanced Ni–B–12.5 mL/L TiO₂ coating was decreased compared with that of pure Ni coating but significantly better than that of Ni–B coating.