(The) diffusion of hydrogen in pure liquid silver and silver-copper alloys

Abstract

The rates of absorption of hydrogen in stagnant liquid pure silver and silver-copper alloys have been measured using a steady-state gas-liquid metal diffusion cell technique. (1) (2) The diffusion cell was formed by immersing an alumina absorption tube containing hydrogen gas at 1 atm in a bath of stagnant liquid silver. The appropriate solution of Fick``s first law was used to calculate hydrogen diffusion coefficient ($D_H$) for pure liquid silver and hydrogen permeability ($R_H$) was calculated for liquid silvercopper alloys. The absorption rate have been found to be controlled by diffusion of hydrogen in liquid metal. The diffusion coefficient of hydrogen ($D_H$) in liquid pure silver in the temperature range of 1010$^\circ$C to 1130$^\circ$C can be described by the following Arrhenious type equation; $$D_H=5.75\times10^{-2}\exp(-1511\pm197)/RT cm^2/\sec$$ The permeabilities ($R_H$) of hydrogen in liquid silver-copper alloys in the temperature range of 1000$^\circ$C to 1160$^\circ$C can be described by the following equations; $$\begin{array}{ll} R_H\; \mbox{pure}\; \mbox{Ag} & = 5.47 \times 10^{-4} \exp \{(-16872.9 \pm 700.0)/RT\} wt\% cm^2/\sec\\ R_H\; Cu\; 1 wt\% & = 2.27 \times 10^{-4} \exp \{(-13859.6 \pm 1068.7)/RT\} wt\% cm^2/\sec\\ R_H\; Cu\; 3 wt\% & = 2.16 \times 10^{-4} \exp \{(-13227.8 \pm 673.9)/RT\} wt\% cm^2/\sec\\ R_H\; Cu\; 5 wt\% & = 2.15 \times 10^{-4} \exp \{(-12719.6 \pm 1351.4)/RT\}wt\% cm^2/\sec\\ R_H\; Cu\; 7\; wt\% & = 1.79 \times 10^{-4} \exp \{(-11909.7 \pm 1565.6)/RT\} wt\% cm^2/\sec \end{array}$$ The rate of absorption of hydrogen in liquid silver-copper alloys have been found to be increased with increased with increasing concentration of copper.