SUBSTRATE METAL OXIDATION MECHANISMS FOR THE APPEARANCE OF DEFECTS IN ENAMEL COATINGS

摘要

The dependence of the oxidation rate of steel beneath an enamel film at its firing temperatures is studied. During the firing process foci of intense oxidation of metal with pronounced dark coloration appear in individual locations on the surface of steel samples, coated with a layer of enamel melt, in air. If the melt in such a focus is enriched with variable-valence oxides to acquisition of electronic conduction, then the oxidation process propagates with constant velocity in the fused enamel along the entire surface of the metal. The propagation velocity of the oxidation process depends on the viscosity and composition of the melt.