Mechanisms of defect formation in enamel coatings induced by substrate metal oxidation

The dependence of the rate of steel oxidation under the enamel film at the temperatures of its firing is considered. In the process of firing, in some places on the surface of steel samples, covered with a layer of enamel melt, in an air atmosphere, centers of intense metal oxidation with a pronounced dark color appear. If in such a focus the melt is enriched with oxides of variable valence until it acquires electronic conductivity, then the oxidation process spreads at a constant rate in the molten enamel over the entire surface of the metal. The rate of propagation of the oxidation process depends on the viscosity and composition of the melt.