Preparation and property of duplex Ni-B-TiO₂/Ni nano-composite coatings

The duplex Nickel-Boron-Titania/Nickel (Ni-B-TiO₂/Ni) coatings were deposited on mild steel by using two baths with Ni as the inner layer. TiO₂ nanoparticles were incorporated into the Ni-B coatings as the outer layer by using solid particle mixing method. The microstructure, morphology and corrosion resistance of the duplex Ni-B-TiO₂/Ni nanocomposite coatings were systemically investigated. The results show that the duplex interface was uniform and the adhesion between two layers was very good. The microhardness of duplex Ni-B-TiO₂/Ni coating was much higher than the Ni coating due to the outer layer of Ni-B-TiO₂ coating. The corrosion resistance of the duplex Ni-B-TiO₂/Ni coating was also significantly improved comparing with single Ni-B coating. The Ni-B-10 g/L TiO₂/Ni coating was found to have the best corrosion resistance among these duplex coatings. This type of duplex Ni-B-TiO₂/Ni coating, with high hardness and good corrosion resistance properties, should be able to find broad applications under adverse environmental conditions.