IRON OXIDE IN ENAMEL GLASS AS DISSOLVED FROM THE METAL BASE*

Abstract

The iron oxide content of an enamel glass was measured by the use of a predetermined curve representing iron oxide versus the index of refraction. It was found that the iron oxide content of the glass adjoining the interface between the enamel and the iron base rises sharply in the early stages of firing to a value close to the solubility limit of the glass after which it gradually falls to a constant value. The iron content at the surface remains low until that at the interface decreases, whereupon the surface concentration correspondingly increases. The cobalt additions resulted in a lower iron content in solution at the interface, but they increased the dendrite content of the glass. A decrease in the cobalt content resulted in an opposite effect. There was a direct relation between the amounts of cobalt and dendrites and the adherence. The effects of temperature and thickness of application are given, and the results are discussed.