Electroplating Of Cu-Sn Alloys And Compositionally Modulated Multilayers Of Cu-Sn-Zn-Ni Alloys On Mild Steel Substrate
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Date
2007-06
Authors
HARIYANTI
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Abstract
Two series of electroplating experiments have been carried out onto mild steel
substrate at 65°C in several electroplating baths under different constant applied
current densities. The objectives of the first series of experiments are to understand the
behavior of electrode position of Cu and Sn in the several alkaline cyanide baths and to
explore the electroplating conditions which are appropriate for fabricating binary Yellow
and White Miralloys coatings. The second series of experiments deals with an
experimental study on electroplating of Compositionally Modulated Multilayer (CMM)
consisting of multiple alternate nano-Iayers of quaternary Yellow and White Miralloys
using dual bath technique (OBT). The kinetics and electrodeposition behavior of Cu-Sn
alloys have been assessed by measuring their cathodic polarization behavior in
selected electroplating baths. The influence of bath composition combined with current
density to the compositions and properties of binary Cu-Sn and quarternary Cu-Sn-Zn-
Ni alloys coatings deposited onto mild steel substrate have been studied in several
electroplating baths. The uniformity of the coatings developed in this experiment is
examined under FE-SEM, while the compositional uniformity of coating and phases
present in the coating are assessed by EOX and XRO respectively. Dense, adherent,
smooth and uniform binary Cu-Sn and quaternary Cu-Sn-Zn-Ni alloys coatings
especially Yellow and White Miralloys, can be deposited with relatively high deposition
rate. Introducing zinc and nickel into the coating does not significantly alter their
chemical and mechanical properties. Formation CMM coatings has significantly
increased the micro-hardness of the coatings. However, fabrication of multilayer
coatings with individual layer thickness < 300 nm are essential. The relationship
between the bilayers thickness (d-1/2,(f..lm)) and coating micro hardness (HV) has been
formulated as HV = 17.37d·1/2 + 602.66. The highest hardness of CMM coating
obtained from this experiment is 689.62 HV and this is achieved by fabricating CMM
coating consisting of multiple alternate thin layers of Yellow and White Miralloys with
individual layer thickness of 20-30 nm. This experiment confirms that the formation of
Cu-Sn or Cu-Sn-Zn-Ni alloys coatings especially CMM coating have made the
application of tin for automotive industries feasible.
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Keywords
Electroplating Of Cu-Sn Alloys And Compositionally Modulated Multilayers , Of Cu-Sn-Zn-Ni Alloys On Mild Steel Substrate