Optimization of Bright Zn-Co-Ni Alloy Coatings and its Characterization

Acidic sulphate bath having znso4.7h2o, coso4.7h2o, niso4.7h2o andthiamine hydrochloride (thc) and citric acid (ca) in combination, was optimized fordeposition of bright zn-co-ni alloy coating on mild steel. bath constituents and operatingparameters were optimized by hull cell method, for highest performance of the coatingagainst corrosion. the effect of current density (c.d.), on deposit characters, such as corrosionresistance and hardness, thickness were studied and discussed. potentiodynamic polarizationand electrochemical impedance spectroscopy (eis) methods were used to assess thecorrosion behaviors. the composition of deposits were determined by spectrophotometericmethod and confirmed by edx analysis. surface morphology of the deposits was examinedusing scanning electron microscopy (sem). the zn-co-ni alloy, with intense peakscorresponding to zn (100) and zn (101) and zn (110) phases, showed highest corrosionresistance, evidenced by x-ray diffraction (xrd) study. a new and cheap sulphate bath, forbright zn-co-ni alloy coating on mild steel has been proposed, and results are discussed