Study On Preparation And Properties Of Decorated Nano-TiO₂ And Nano-TiO₂ Composite Coatings By Electroless Plating

In this paper,Ni-P allay was deposited onto the surface of nano-TiO₂ by electroless plating to prepare Ni-P/TiO₂ composite particles.The effects of bath composition and operating condition on composition,microstructure and morphology of Ni-P/TiO₂ composite particles were investigated.Photocatalytic performance of these composite particles was evaluated.And the nano-TiO₂ particles were introduced into electroless plating bath based on electroless plating Ni-P and Ni-Cu-P coatings to make the nano-TiO₂ particles and Ni,P,Ni,Cu,P matrix co-deposit to obtain nano-TiO₂ electroless composite coatings.The preparation process of elestroless composite plating was optimized by perpendicular experiment method.The effects of bath composition and operating condition on nano-TiO₂ content in electroless composite coatings were researched. At the same time,microstructure,morphology and composition of Ni-P/TiO₂ composite particles and composite coatings were characterized by XRD,SEM and EDS techniques.The properties of composite coatings,such as Micro-hardness, wear resistance and corrosion resistance were investigated.Photocatalytic performance of nano-TiO₂ composite coatings was evaluated.The result shows that Ni-P/TiO₂ composite particles with controlled Ni,P contents can be obtained by changing electroless bath composition and operating condition.Degradation rate of methyl orange can reach 89.22%under UV irradiation 5h when Ni content of Ni-P/TiO₂ composite powders is 6.45wt%. Deposition low Ni content onto nano-TiO₂ can improve photocatalytic performance of Ni-P/TiO₂ composite particles.Nano-TiO₂ content in Ni-P-nano-TiO₂ composite coatings increases with the increase of nano-TiO₂ concentration in electroless bath.Nano-TiO₂ content can reach 11.32wt%when nano-TiO₂ concentration in bath is 8g/L.Uniform distribution of nano-TiO₂ in composite coatings can increase wear resistance of compsite coatings.The photocatalytic performance of Ni-P-nano-TiO₂ composite coating under optimized preparation process is slightly worse than nano-TiO₂ particles.Cu content in electroless Ni-Cu-P coatings increases significantly with the increase of CuSO₄·5H₂O concentration in bath.But Ni and P content decreases. Introduction Cu into Ni-Cu-P coatings decreases the size of cystiform structure of Ni-P matrix.The crystallinity of coatings increases with the increase of Cu content.Nano-TiO₂ content in Ni-Cu-P-nano-TiO₂ composite coatings increases in the first and then decreases with the increase of nano-TiO₂ concentration in electroless bath.Nano-TiO₂ content can reach 7.75wt%when nano-TiO₂ concentration in bath is 6g/L.The corrosion resistance of Ni-Cu-P-nano-TiO₂ composite coatings is much better than Ni-Cu-P coatings and Ni-P-nano-TiO₂ composite coatings.The photocatalytic performance of Ni-Cu-P-nano-TiO₂ composite coating under optimized preparation process is slightly worse than Ni-P-nano-TiO₂ composite coating uder the same condition.