Research On The Process Of (Zn-Ni)/Al₂O₃ Composite Deposition With The Aid Of Hyper Dispersant

The properties of composite coating is relative to the dispersion of nano-alumina in plating solution and nano-powder content in coating which is leading by particle dispersible quality. Besides, Hyper dispersant has attracted more attention because it is benefit to dispersing some organic pigments and inorganic particles. The (Zn-Ni)/Al2O3 composite coating was obtained by addition of two kinds of hyper dispersant. The effect of hyper dispersant on the dispersion of nano-alumina in plating solution was investigated in this paper. The effect of electrolyte and operating parameters on surface morphology and Al2O3 content in coating was investigated in detail by scanning electron microscopy and spectrophotometric determination. The hardness and corrosion resistance were evaluated by , the anticorrosion mechanism was also discussed by XPS as well.The composited content of particles in coating was high when 0.5% Super-3900 was added into Al2O3 suspention before plating the composited content increased with the increase of Al2O3 concentration in plating solution and the time of stirring before plating and increased as a peak curve with plating temperature, cathodic current density and pH value. As a result, the optimal condition was: Al2O3 concentration in plating solution is 12.5 g/L, the time of stirring before plating is 16 hours, plating temperature is 35℃, cathodic current density is 4.0 A/dm2, pH value is 4.5~5.0;The Al2O3 content in coating increased obviously by adding lower concentration of Mps-DL, and it was stabilized by stirring 8 hours before plating. The dispersant was benefit to the brightness of coating as well. The power ultrasonic was useful to improving nano-powder content in coating.The corrosion potential was the biggest and the corrosion current was the smallest one when the concentration of Super-3900 was 0.5%; The corrosion potential was increased with the addition of Mps-DL, but the smallest corrosion current is under 0.01% Mps-DL.The rust time was the longest one when the concentration of Super-3900 was 0.5% as well as Mps-DL was 0.01%. It was increased as a peak curve with Al2O3 concentration in plating solution and pH value increased gradually with cathodic current density; The corrosion weight...