PREPARATION OF TIN FILM ON BRASS BY CAPD AS A DECORATION SYSTEM

Titanium nitride (TiN) films are deposited onto brass (62 wt.% Cu and 38 wt.% Zn) substrates by the cathodic are plasma deposition process ( CAPD). The colour main wavelength and reflectivity of the films are me asured by a chromatometer. The pore ratios of the films with different thickness are investigated by a light transmission image analysis sys tem. The corrosion resistance of this system is studied by electrochem ical analysis. Scanning electron microscopy, transmission electron mic roscopy and Auger electron spectroscopy are employed to study the meta llography, the preliminary deposition process of CAPD and the interfac e between the films and substrates respectively. The results show that : (1) the decorative property of TiN/brass system prepared in a certai n CAPD parameter range can reach that of standard 24 carat gold; (2) a s the nitrogen partial pressure increases, the main wavelength of the film increases and tends to values near and around that of 24 carat go ld and the reflectivity of the film increases and reaches that of 24 c arat gold; (3) as the substrate temperature increases from about 190 d egrees C to about 700 degrees C, the reflectivity of the film dropped seriously but the main wavelength of the film is hardly affected; (3) the light transmission pore ratio falls as a reciprocal function of th ickness of the TiN film; (4) finally, the corrosion resistance of this system in an artificial human sweat solution is improved largely comp ared with that of the bare decorative brass.