Preparation of coloured composite films of Ni/organic pigments by immersion plating over zinc surface

Abstract

Colour coatings of Ni–pigment composite film over a zinc surface using the immersion plating technique were investigated. Two types of approaches were applied in synthesizing the composite films. In one method, composite films were synthesized simply by immersing a zinc substrate in an aqueous solution containing nickel ions and pigment particles dispersed with the aid of a surfactant mixture containing nonionic azobenzene surfactant (AZPEG) and n-sodium dodecyl sulfate (SDS). In the other method, composite films were synthesized in two steps. In the first step, a thin pigment film was deposited on a zinc substrate by micelle disruption technique using AZPEG followed by deposition of nickel in the second step: the immersion of the substrate in an aqueous solution containing nickel ions. Both of these methods produced a uniform coloured composite film with good adhesion. The adherence of these composite films was enhanced by the co-deposition of PMMA latexes with the pigment followed by thermal treatment of the coatings. The contact angle measurement revealed that all the composite films investigated in the present study had a greater degree of water repellency property than that of the electroplated nickel.