Stationary concentration of hydrogen in molten aluminum

Abstract

It was explained in the previous paper that stationary concentration of hydrogen in molten aluminum depended upon the melting processes.This paper discusses the effects of humidity in the atmosphere on hydrogen concentration in molten aluminum. Supplementary experiments were also performed to study the effects of melting process on stationary concentration of hydrogen in the melt.Molten aluminum (99.99% in purity) was held in the atmosphere, of which the humidity was controlled by six stages, and their hydrogen contents were measured at intervals of a certain time. The results showed that the stationary concentration of hydrogen (Cs) could be expressed by function of the humidity (P<H2O>) as follows:Cs = K√P<H2O>As the results of the supplementary experimants and the above relation between Cs and P<H2O>, the following considerations were drawn concerning the effects of melting process on Cs.(1) It was due to the higher humidity in the atmosphere that Cs of the melt held in a resistance furnace sealed with a cover was higher than that held in an induction furnace.(2) It was due to the disposition of interface between the melt and crucible that hydrogen in aluminum, which had been melted in vacuo, increased with the holding time in the air, but not converged into a stationary concentration.