الفهرس 
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Abstract
The effect of plating conditions such as current density and plating time in addition to the effect of Co”1”2 and Cd+2 ions added to acidic zinc electrolytes on the corrosion resistance of zinc coats were examined. The zinc coats morphology obtained after plating and after corrosion were also investigated. The study shows also the effects of chromating process as a post treatment method for zinc coat. The corrosion rates of zinc coats were measured and calculated using weight loss and electrochemical techniques. The formation of red rust due to immersion in 3.5% by weight NaCl on zinc coat was observed visually with time. The results indicate that plating time equal 120 seconds and 15 A/dm2 current density gives minimum corrosion rates. The corrosion resistance improves by increasing concentrations of metallic additives where the addition of 8.0 g/1 Co+2to zinc electrolyte decreases the corrosion rate by25.2% | and the addition of 2.0 g/1 Cd+2 gives 37.5 % reduction. The effect of adding combined metallic ions (Co+Cd) to zinc electrolyte achieved a 46.4% tion in corrosion rate. The hardness of pure zinc coats and the developed (Zn-Co, Zn-Cd and Zn-Co-Cd) was measured. The morphology of zinc sits, examined by SEM shows a significant change with the addition of Co . Cd ions to the zinc electrolyte. The examination of the morphology of zinc immersed in 3.5% by weight NaCl for 48 hours shows a relatively lower ition effects on the surface of the developed zinc in comparison to pure coats. This sustains the corrosion measurements study. Post treatment,