Abstract: A lead-free ceramic glaze comprising, by weight:(i) between about 27 and 35% SiO.sub.2 ;(ii) between about 9 and 15% Al.sub.2 O.sub.3 ;(iii) between about 26 and 34% B.sub.2 O.sub.3 ;(iv) between about 4 and 9% BaO;(v) up to about 2.5% CaO;(vi) between about 3 and 8% SrO;(vii) between about 6 and 12% ZnO;(viii) up to about 1% K.sub.2 O;(ix) between about 1 and 4% Li.sub.2 O;(x) between about 1.5 and 3% Na.sub.2 O; and(xi) balance of minor impurities.Also disclosed are ceramic substrates spray coated with such composition and a method for making a lead-free glaze to a ceramic substrate using lower firing temperatures, on the order of 1550.degree. to 1650.degree. F. (843.degree. to 899.degree. C.).

Abstract: A lead-free ceramic glaze comprising, by weight:(i) between about 27 and 35% SiO.sub.2 ;(ii) between about 9 and 15% Al.sub.2 O.sub.3 ;(iii) between about 26 and 34% B.sub.2 O.sub.3 ;(iv) between about 4 and 9% BaO;(v) up to about 2.5% CaO;(vi) between about 3 and 8% SrO;(vii) between about 6 and 12% ZnO;(viii) up to about 1% K.sub.2 O;(ix) between about 1 and 4% Li.sub.2 O;(x) between about 1.5 and 3% Na.sub.2 O; and(xi) balance of minor impurities.Also disclosed are ceramic substrates spray coated with such composition and a method for making a lead-free glaze to a ceramic substrate using lower firing temperatures, on the order of 1550.degree. to 1650.degree. F. (843.degree. to 899.degree. C.).

Abstract: A high-silica ceramic glaze, having a low coefficient of thermal expansion, suitable for application to alumina bodies, is disclosed. The glaze consists essentially, by weight percent, of 35 to 54 percent SiO.sub.2, from 7 to 11 percent Al.sub.2 O.sub.3, from 17 to 25 percent B.sub.2 O.sub.3, from 2 to 3 percent CaO, from 2 to 21/2 percent ZnO, from 41/4 to 5 percent Na.sub.2 O, from 81/2 to 21 percent SrO, and from 0.7 to 1 percent of a mixture of K.sub.2 O, Li.sub.2 O and MgO, and minor impurities.

Abstract: A high-silica ceramic glaze, having a low coefficient of thermal expansion, suitable for application to alumina bodies, is disclosed. The glaze consists essentially, by weight percent, of 48 to 54 percent SiO.sub.2, from 7 to 11 percent Al.sub.2 O.sub.3, from 161/2 to 20 percent B.sub.2 O.sub.3, from 11 to 14 percent BaO, from 2 to 3 percent CaO, from 2 to 21/2 percent ZnO, from 41/4 to 51/4 percent Na.sub.2 O, and from 0.4 to 1 percent K.sub.2 O. Li.sub.2 O and MgO to the extent of up to about 1/4 percent and 1 percent, respectively, can also be tolerated, as can minor amounts of other impurities.