BUBBLE STRUCTURE OF ENAMEL COATINGS AND ITS DETERMINATION

The bubble structure of enamel coatings affects their behaviour in cor rosion environments and their applicability. in the protection of meta ls against corrosion. A method enabling to characterize the bubble str ucture of enamel coatings was developed. After preparing a planar sect ion parallel to the coating surface, the diameters of bubble sections are measured, preferably by image analysis. The resulting size distrib ution of two-dimensional bubble sections can be converted in the size distribution of three-dimensional bubbles using a stereological method . Examples of two different enamel coatings on steel substrate show th e applicability of this method to real enamel systems.