Publications

A stable Ni-Cr-P alloy plating solution was developed, based on the sulfate salts of the electroactive ingredients. This solution was successfully used at room temperature to produce bright, shiny and adherent deposits of Ni-Cr-P alloys. Electron microscopy, energy dispersive spectroscopy and X-ray diffraction were used to analyze the resulting deposits. The composition of the alloy was found to be controlled by current density, fluid dynamics and camphor presence. Unpublished data also indicate that it is controlled by the sodium hypophosphite concentration. The sodium hypophosphite acted as a reducing agent and the camphor served as an apparent selective membrane and a plating additive. Current efficiency was also found to be controlled by the same parameters. A potentiodynamic sweep method was used to test the corrosion resistance of the resulting deposits. The alloys produced in this solution displayed excellent corrosion resistance. The corrosion failure mode for these alloys was found to be cracking of the deposits followed by dissolution of the substrates from beneath. No dissolution of the deposits was apparent in the micrographs taken from the samples used in the corrosion tests. A small inclusion of indium in the alloy was attempted to modify the properties. It was found that the cracking was reduced but not eliminated by adding indium. © 1992.

The thermodynamic data needed to estimate the heat generation characteristics of Li/BCX and Li/SOCl2 cells were determined using two experimental techniques, equilibrium or reversible cell discharge and measurement of open circuit potential as a function of temperature. The results obtained showed that the reversible cell potential (Er), the temperature dependence of the reversible cell potential (dEr/dT) and thermoneutral potential (Eh) of the BCX cell were respectively, Er,25oc = 3.74 V, dEr/dT = -0.857 ± 0.198 mV/K and Eh= 3.994 ± 0.0603 V. The respective values obtained for the Li/SOCl2 cell were Er,25oc = 3.67 V, dEr/dT = -0.776 ± 0.225 mV/ and Eh = 3.893 ± 0.0776 V. The difference between thermoneutral potential of Li/BCX and Li/SOCl2 cells is attributable to the difference in their electroactive components.

A two-dimensional and time-dependent thermal model of a multicell common pressure vessel (CPV) nickel-hydrogen battery was developed. A finite element solver called PDE/Protran was used to solve this model. The model was used to investigate the effects of various design parameters on the temperature profile within the cell. The results were used to help find a design that will yield an acceptable temperature gradient inside a multicell CPV nickel-hydrogen battery. Steady-state and unsteady-state cases with a constant heat generation rate and a time-dependent heat generation rate were solved. © 1991, The Electrochemical Society, Inc. All rights reserved.

Hydrogen gas diffusion coefficients and solubilities as well as water uptake values are reported for Dow s short-side-chain perfluoro-sulfonic and -carboxylic membranes of different equivalent weight (EW). The diffusion coefficients and solubilities were determined with an electrochemical test cell. Hydrogen solubility decreases with increasing EW in the lower EW range and tends to level off at higher EWs for both types of membranes. Both hydrogen solubility and diffusion coefficients of a sulfonic membrane with EW higher than 800 are higher than the corresponding values of a carboxylic membrane of similar EW. An unusual maximum is observed in the diffusion coefficient-EW plot of sulfonic membranes. Water uptake decreases with increasing EW for both types of membranes. Various trends in the hydrogen diffusion coefficients and solubilities are discussed in terms of a number of physical and morphological properties, such as the percent of crystallinity, intrusion of one phase into another phase, extent of ion-pair formation, and pore sizes of membranes.

Through a continuous recording of the cell voltage, heat flow, and current, the effective thermoneutral potential, Eetp of Li/BCX and Li/SOCl2 cells were determined in the temperature range, 0-60°C. The depth of discharge (DOD), temperature (T), and cell type (cell chemistry) affect the effective thermoneutral potential. The effective thermoneutral potential, Eetp differs from the classical thermoneutral potential of a cell because it takes into account the heat flow due to nonfaradaic processes. The average effective thermoneutral potential at 25°C (determined by selecting the most constant region of Eetp vs. time of discharge) was 4.0 and 3.84 V for BCX and Li/SOCl2 cells, respectively. Based on the classical approach, the reversible cell potential, Er and temperature dependence of reversible cell potential, dEr/dT for BCX cell were 3.74 V and -0.852 mV/K, respectively, and for Li/SOCl2, Er = 3.67 V and dEr/dT = -0.567 mV/K. The thermal polarization (Eetp - El), where El is the load voltage, for both cells, showed that they are most thermally efficient near 40°C. A measure of the heat flow for both cells at 50% DOD supports this observation. An overall reaction proposed for the BCX chemistry is supported by the calculated thermodynamic parameters.

The bulk heat capacities of Li/BCX and Li/SOCl2 cells were determined at 0 and 100% depth-of-discharge for 2.0 V cut-off voltage, in the temperature range 0 to 60 °C by a method that did not involve the destruction of the cell nor the contact of cell with a liquid. The heat capacity of Li/BCX cell is an important parameter for the design of a thermal control system for Li/BCX batteries. The heat capacities are found to be dependent on state-of-charge - increasing with depth-of-discharge. The Li/BCX DD-cell has a lower heat capacity (0.154 to 0.201 cal/(g K)) than a high rate Li/SOCl2 D-cell (0.191 to 0.221 cal/(g K)). The results obtained by this method compare favorably well with results reported in the literature through other methods. The bulk heat capacities of the cells did not change significantly in the temperature range 0 to 60 °C. © 1992.

The distributions of potential and current density around a cathodically protected pipeline in seawater were determined using the boundary element technique. A nonlinear polarization curve for a low carbon steel in artificial sea water was obtained from dc-potentiodynamic measurements and was fitted for use as the boundary condition on the pipe. The program was used to evaluate cases in which one or two aluminum sacrificial anodes are used to protect a low carbon steel pipe in seawater. The results show that the number of anodes, the sizes of the anodes, and the distance between the anodes and the cathode are of importance for cathodic protection.

The mathematical model developed by Sunu and Bennion has been extended to include the separator, precipitation of both solid ZnO and K2Zn(OH)4, and the air electrode, and has been used to investigate the behavior of a primary Zn-Air battery with respect to battery design features. Predictions obtained from the model indicate that anode material utilization is predominantly limited by depletion of the concentration of hydroxide ions