الفهرس 
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Abstract
The electroplating of metals from a cyanide solution was one of the most important
s used for electroplating, it gave excellent quality coatings. However, in the last
few years, due to environmental controls and safety policies for operators, the plating
industry has been interested in replacing the toxic cyanide baths with environmentally
friendly baths without loss in the quality of coating. Coatings from such solutions as
pyrophosphate, citrate, sorbitol and glycerol-based have been studied, in order to
improve the corrosion resistance of steel substrate with the development of
electroplated metals coating.
In the present work, systematic studies on the electrodeposition of individual metals
(copper and zinc) and their binary alloy (copper-zinc) on steel substrates from citrate
baths were carried out and their corrosion resistance against corrosive medium (3.5 %
NaCl) was investigated. This study includes two main parts.
Part 1
In this part, systematic studies on the electrodeposition of individual metals (copper
and zinc) on steel substrates from citrate baths were established under different
experimental conditions such as bath composition, current density, pH, deposition
time and temperature to find the optimum bath composition and optimum operating
conditions. This investigation comprises the study of the effect of these variables on
the cathodic current efficiency, throwing power and cathodic polarization, in order to
find the optimum bath composition and conditions that have high cathodic current
efficiency with excellent throwing power. The morphology, characterization, crystal
structures and crystal size of the deposits were also examined. The optimum
conditions for producing sound and satisfactory copper deposits were: 0.025 M
CU2C6H401.1.5H20, 0.2 M citrate buffer (0.101 M Na3C6Hj07. 2H20 and 0.099 M
C6Hg01) at pH=4.2, deposition time=15 min., 3 m/vcm’, and 20°C and that for zinc
were: 0.025 M Zn3CI2HIOOI4. 2H20, 0.3 M citrate buffer (0.285 M Na3C6Hs07. 2H20
and 0.015 M C6HS01) at pH=6.2, deposition time=30 min., 3.5 mNcm2 and 25°C.