Enamel frits for acid-resistant one-coat enamelling on unpickled steels

摘要

An enamel frit for producing an acid-resistant enamelled steel in a single coating comprising at least about 40% of silicon atoms, 50% of silicon atoms and boron atoms, where the proportion of the boron atoms should not fall below 6.5%, 63% of silicon atoms, boron atoms and sodium atoms, where the proportion of the sodium atoms should not fall below 7. 5%, each relative to the overall total of the non-oxygen atoms in the frit, the proportion of the remaining non-oxygen atoms being less than about 37%, and 1.0 to 1.2% of cobalt atoms. In addition, there are (1) x fluorine atoms with 1%x11% and at least y lithium atoms and at most 2y lithium atoms with y=(15/x)+5 being present, the proportion of lithium atoms being from about 6.3% to 20% relative to the overall total of the non-oxygen atoms in the frit, or (2) y lithium atoms with 6.3% y20% and at least x fluorine atoms and at most 2x fluorine atoms with x=15/(y-5) being present, the proportion of fluorine atoms being from about 1% to 11% relative to the overall total of the non- oxygen atoms in the frit.