Publications

Hydrogen permeation experiments were carried out to investigate the effect of thallium on hydrogen entry into HY-130 steel. These experiments show that the presence of thallium ions in an electrolyte drastically increase the hydrogen entry rate. The hydrogen entry efficiency and hydrogen surface coverage were increased by a factor of 10 and 6, respectively In order to fit the permeation experimental data, the lyer-Pickering-Zamanzadeh (I-P-Z) hydrogen permeation model was modified by including a mass-transfer term in the discharging equation. The relationship between hydrogen permeation and the hydrogen evolution reaction were investigated and new relationships were obtained. © 1994, The Electrochemical Society, Inc. All rights reserved.

It is shown that underpotential deposition of zinc from a plating solution inhibited the discharge of hydrogen on HY-130 steel. In the presence of a monolayer coverage of Zn, hydrogen evolution currents were reduced by 58% compared with values obtained on bare HY-130 steel. The observed effects are due to the kinetic limitations of the hydrogen discharge reaction and the suppression of hydrogen absorption by the deposited monolayers. The hydrogen atom direct entry mechanism was used and a mass transfer term was introduced into the permeation model to interpret the experimental data. In the presence of zinc monolayers, the hydrogen entry efficiency in the alloy and the hydrogen entry rate constant were reduced by a factor of three and by 74%, respectively. © 1994.

A mathematical model is presented for the discharge of a NiOOH/H2 cell. This model includes diffusion and migration in the electrolyte phase as well as proton diffusion and ohmic drop across the solid active material in the porous nickel electrode. A theoretical analysis of the cell performance is presented for different design parameters using this model. It is predicted that proton diffusion in the solid active material is the main factor in limiting the cell voltage and the utilization of the active material. It is also predicted that use of a thick nickel electrode is an effective method for increasing electrode capacity per unit area. This model can be used to predict the two-discharge-plateau behavior of a nickel electrode.

Linear sweep voltammetry was used as an in-situ technique to characterize the electrochemically formed thin layers of Fe-Ni alloys. By using a potentiostatic pulse-plating technique, organic additives were shown to be essential for enabling deposition of the binary alloy from sulfate electrolytes. This study found the optimum plating conditions and a new formulation for a plating bath.

Polarization experiments and a potentiostatic pulse technique have been used to show that a monolayer coverage of zinc effectively inhibits the absorption of hydrogen into Monel K500. By depositing a monolayer of zinc on Monel K500 the hydrogen evolution reaction and hydrogen ingress flux rate were reduced by 60%. © 1994, The Electrochemical Society, Inc. All rights reserved.

Polarization and permeation experiments showed that a monolayer coverage of lead (Pb) effectively inhibited the hydrogen (H) evolution reaction and H penetration through type 718 (UNS N07718) alloy. Observed inhibition effects were a result of the kinetic limitations of the H discharge reaction and suppression of H absorption on the deposited monolayer. H evolution reaction and H permeation rates were reduced by approximately 67% and 70%, respectively.

A mathematical model of a hermetically sealed lead-acid cell is presented. The model was used to study the effect of having an excess negative electrode and the transport rate of oxygen across the separator on the oxygen evolution at the positive (PbO2) electrode and the reduction of oxygen at the negative (Pb) electrode during charge and overcharge. Results from the model showed that sufficient transport rate of oxygen across the separator is the key to successful operation of a sealed lead-acid cell. Consequently, a separator with optimal characteristics for oxygen transport must be considered in the design of hermetically sealed lead-acid cells. © 1993.