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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.57  No.7 (2016)  >  pp.1165-1170

MATERIALS TRANSACTIONS
<<Previous article Vol.57  No.7 (2016)   pp.1165 - 1170 Next article>>

Electrodeposition of Zn–Zr Oxide Composite from Dispersed-Particle-Free Solution

Hiroaki Nakano1), Yosuke Hara2), Satoshi Oue1), Shigeo Kobayashi3)
1) Department of Materials Science & Engineering, Kyushu University 2) Department of Materials Process Engineering, Kyushu University 3) Department of Applied chemistry and Biochemistry, Kyushu Sangyo University

Electrodeposition of Zn–Zr oxide composite from an unagitated sulfate solution containing Zn2+ and Zr ions was investigated at pH 1–2 and at 313 K under galvanostatic conditions. The Zr content was higher in deposits formed from the solution at pH 2 than in those formed from the solution at pH 1 and initially decreased with increasing current density; however, when the current density was increased further, the Zr content in the deposits increased. This increase in Zr content was attributed to the acceleration of the hydrolysis of Zr ions by an increase in hydrogen evolution in the solution in the vicinity of cathode. In solutions containing Zr ions, Zn deposition was substantially polarized because of the electric resistance of film of the Zr oxide formed by the hydrolysis of Zr ions. The pH in the vicinity of the cathode, as measured using an Sb microelectrode, was approximately 2.2, which is similar to the critical pH for the formation of ZrO2. Scanning electron microscopy and energy-dispersive X-ray spectroscopy point analysis of the deposits revealed that granular Zr oxide was deposited at the surfaces of the Zn platelet crystals and in the voids between the crystals. Polarization curves in 3 mass% NaCl solution revealed that the corrosion potential of the deposited Zn–1.1 mass% Zr oxide films was more noble than that of Zn films and that the corrosion current density of the Zn–1.1 mass% Zr oxide films was lower than that of Zn films.


Keyword:
electrodeposition, zinc, zirconium oxide, polarization curve, corrosion potential, corrosion current density, antimony microelectrode, oxide composite, hydrolysis

Received: March 04, 2016
Accepted: April 07, 2016 , Published online: June 25, 2016

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