Physiochemical Effects of SiC and ZrO2 Particle Fillers on the Properties of Enamel Coatings

The ceramic particles of SiC and ZrO2 are embedded as fillers in the enamel coating with varying contents of 0.03, 0.05, and 0.1 wt %, and the surface properties are measured. It is found that the addition of ceramic fillers indeed causes changes in surface properties. The roughness was influenced mainly by the particle size embedded. The contact angle decreased at 0.03 and 0.05 wt % and equivalent to that of no filler at 0.10%. Our analysis suggested that the contact angle is influenced by both surface roughness and surface morphology (with chemical composition). The microstructure and elemental analysis suggest that the chemical composition and shape of Al, Ce, Ca, and P-rich aggregates on the enamel surface are showing significant changes when fillers are added. It is observed that the Al- and Ce-rich aggregates decrease both in number and size as the filler content increases, and Ca-rich aggregates change their shape from needle to spot at 0.1 wt % inclusion. The washability is notably improved at 0.1 wt %, which corresponds to the content where the drastic microstructure change occurred. The examination of the contaminated surface revealed that the phosphate component in the contamination has reacted with the Ca-rich phase of the needle-shape during the process of burning, thus inhibiting an easy removal of the contamination. Therefore, the formation of the Ca-rich phase of the needle-shape on the enamel surface should be suppressed for easy-cleaning enamel coatings for cooking wares.