Characterization of Hydrogen Permeation Through a Corrosion-Resistant Zinc-Nickel-Phosphorus Alloy

Abstract

Hydrogen permeation characteristics of a new Zn-Ni-P alloy were studied and compared with that of a Zn-Ni alloy. The Zn-Ni-P alloy was deposited from an acid sulfate bath containing 0.5 M nickel sulfate (NiSO 4 ), 0.2 M zinc sulfate (ZnSO 4 ), 0.5 M sodium sulfate (Na 2 SO 4 ), and 100 g/L sodium hypophosphite (NaH 2 PO 2 ) at pH 3. The permeation characteristics of the alloy were studied and compared qualitatively with that of Zn-Ni alloy under cathodically polarized and corroding conditions. The Zn-Ni-P alloy had better permeation inhibition characteristics in terms of permeation efficiency through the alloy. The Iyer-Pickering-Zamanzadeh (IPZ) model was used to quantitatively estimate the various kinetic parameters associated with hydrogen permeation for Zn-Ni-P alloy under polarized conditions. The Zn-Ni-P alloy had superior permeation inhibition properties compared to the Zn-Ni alloy.

Hydrogen Absorption Behavior into Zn and Zn–Al Coated Steels during Corrosion in Aqueous Solutions

“…These results are also in good agreement with the researches done by other researchers. [15][16][17][18] In addition, even if hydrogen atoms can be absorbed into Zn and Zn-Al coating layers, hydrogen diffusion in the coatings is considered to be slow because diffusion coefficient of hydrogen atom in Zn or Zn alloy coatings is much lower by comparison with that for steels without the coatings. [19][20][21] Therefore, it is considered that i per cannot be observed for Zn and Zn alloy coated steels during the immersion test due to slow kinetics of hydrogen evolution reaction and slow diffusion rate of hydrogen in Zn and Zn alloys while the coatings are intact.…”

Development of Novel Process for the Deposition of Nanostructured Ternary Alloys and Composites for Replacement of Cadmium Coatings

“…The I-P-Z mechanistic model assumes that during hydrogen discharge on the surface, T] » RT/F so that the backward reactions are negligible and the surface coverage is low enough so that a Langmuir isotherm can be used for the hydrogen coverage. With these assumptions and after suitable modifications, the following relationships were obtained to correlate the hydrogen charging (cathodic) current ic and the permeation current ia with the various kinetic parameters [18]:…”

“…The transfer coefficient, a, required for the parameter estimation was derived by solving a quadratic equation involving Sc and Sa, the cathodic and anodic slopes obtained from Figures 34 and 35 [18]. Out of the two roots for a, the one that resulted in negative values of /" and A: "was neglected.…”

“…Also the barrier properties of the coating increases with increased nickel content in the deposit. Several attempts have been made earlier to decrease the anomaly and increase the nickel content by either introducing an inert species in the bath or by developing a ternary alloy [17][18][19][20][21][22][23][24]. Nonyl phenyl polyethylene oxide (NPPO) has been used to reduce the Zn-Ni ratio and produce more corrosion resistant deposits.…”

“…Codeposition of phosphorous along with Zn-Ni alloy improves the corrosion resistance [17] and hydrogen permeation [18] characteristics of the deposit. Zhou et al [19] have studied the effect of tin additions on the anomalous deposition behavior of Zn-Ni alloys.…”