Study of Some Phenomena Associated with the Adherence of Sheet Iron Ground Coats

Cobalt and nickel are deposited on the surface of the base metal during the firing of sheet iron ground coats. These deposits, which are metallic in nature, at least at higher firing temperatures, increase with increasing firing temperature. They also increase with the amount of cobalt and nickel present in any one frit and with the fluidity of the enamel. One reason why cobalt is generally considered a better adherence agent than nickel is that cobalt has a greater tendency to deposit during firing. Ground-coat adherence is generally associated with a certain amount of deposition of cobalt and nickel on the metal surface. This deposition in turn is associated with a roughening of the metal surface which is believed to be a large contributory factor in enamel adherence.