Study Of Electroless Ni-P-Nano-TiO₂ Composite Plating By In Situ Polymerization

Electroless nano-composite coatings, combination of electroless plating and the excellent properties of the nano particles in them, possess many special properties. All of this has brought a wide range investigation on it in surface finishing. In this paper, the study status and development trends of electroless plating and electroless nano-composite plating are summarized. Then the attention will be put on the dispersion problem of nano particles in the composite coatings which afflicting the researchers.Nowadays people can obtain electroless nano-composite coatings mainly by adding nano-powders into the plating bath, in which the particles may co-deposit with metal. But the nano particles will aggregate inevitably. In this paper, electroless Ni-P-nano-TiO₂ composite coatings were produced by in situ polymerization, that is adding TiO₂ sol into the bath after adjusting its pH value. This method can perfectly solve the dispersion problem of nano-TiO₂.SEM and EDX were used to character the composition and microstructure of the Ni-P-nano-TiO₂ composite coatings. The results showed that the nano-TiO₂ particles with size ranging from 20 nm to 30 nm were well dispersed in the coatings. And the coatings without any pore had uniform structureBy reason that the content of nano- particles in the coatings was very low, the author taked some measures to raise it. And then some effectiveness comes out. The content of TiO₂ increases to 6%(wt).Also the hardness of the composite coatings was improved.