Redox dynamics in the high-temperature float processing of glasses. I. Reaction between undoped and iron-doped borosilicate glassmelts and a gold-tin alloy

摘要

X-ray emission and Rutherford backscattering spectroscopies wee used to characterize the dynamic chemical response in two borosilicate glassmelts (both Pyrex~(TM) composition, one with 0.08 at.% Fe added) reacted with a Au-30Sn liquid alloy. Reactions were done at temperatures of 1250-1350 deg C for 30 min under a reduction atmosphere. Because of the metal alloy design and the glass structure, the chemical diffusion response shows less Sn incorporation into the glassmelt than in conventional commercial soda-lime float; the addition of Fe~(3+) acts decisively to reduce the kinetics of Sn penetration. The results indicate a cation-diffusion-limited reduction reaction as the dominant kinetic mechanism working towards equilibrium in the silicate melt/metal melt system. The proposed kinetic model is consistent, too, with many idiosyncratic features of chemical concentration profiles observed in soda-lime float glass.