G.A.EL-Mahdy (Chemistry Dept.
,
Faculty of Science
,
Helwan University
,
Helwan
,
Cairo
,
EgyptS-S.MahmoudChemistry Dept.
,
University College for Women
,
Ain-Shams University
,
Helopolis
,
Cairo
,
Egypt)
材料科学技术（英文）
The effect of fluoride ions on the formation and dissolution behaviour of anodic oxide films on Ti has been investigated in acidic fluoride media (pH=1) using impedance and galvanostatic techniques. A5 the fluoride ion concentration and temperature increase the rate of oxide film formation decreases while the dissolution process increases. oxide film formed at high tem-perature and formation voltage was found to contain more defect sites in the film than that formed at a lower one. Activation energies are calculated during the oxide film formation and dissolution and found to be 20.76 and 28.72 kJ/mol, respectively. Formation rate and reciprocal capacitance data are reported as a function of polarizing current density. Values are recorded for the electrolytic parameters A and B. Potentiostatic curves are derived from the galvanostatic results.
关键词:
A.A.Zaghloul
,
G.M.EI-Subruiti and A.M.Ahmed(Chemistry Depatment
,
Faculty of Science
,
Alexandria University Alexandria
,
Egypt)
材料科学技术（英文）
The cementation reaction of copper on zinc metal in solutions of different concentrations ofcopper sulphate, at 25℃, has been studied and it is found to be a first order reaction. Moreover,the rates of this reaction at 0.15 mol'L-1 copper sulphate solution have been measured in a varietyof ethanol-water media at temperatures from 20℃ to 40℃. The correlation between the masstransfer coefficient and the dielectric constant has been investigated. Also, the thermodynamicparameters of activation have been calculated. The isokinetic relationship reveals the existenceof compensation effect, where the solute-solvent interactions play an important role.
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