Equilibrium concentration of hydrogen in molten aluminum in the ordinary atmosphere

Abstract

Studies were made on the variation of hydrogen concentration in molten aluminum with holding time. Pure aluminum was melted under various melting conditions and some molten baths different in initial concentrations of hydrogen were obtained. The hydrogen ion concentrations of the molten metals were measured at regular intervals being held in the ordinary atmosphere.The results of the experiment were summarized as follows: Equilibrium concentration of hydrogen widely varied with melting conditions and it did not correspond to a linear function of partial pressure of water vapor in the atmosphere.The following conclusions were drawn from the above results of the experiment.(1) The rate of hydrogen evolution from the molten metal depended upon the diffusivity of hydrogen through the oxide film.(2) Equilibrium concentration of hydrogen was varied with hydrogen diffusivity and water vapor permeability through the oxide film as well as with the thickness of the film.