Transparent lead-free glazes
AssigneeCorning Incorporated
InventorJaroslava M. Nigrin
Life of this patent
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Abstract
This invention relates to lead-free and cadmium-free frit compositions for glazes and enamels which consist essentially, expressed in terms of weight percent on the oxide basis, of ______________________________________ SiO.sub.2 51-59 CaO 0-7 Li.sub.2 O 0-2 SrO 0-12 Na.sub.2 O 3.5-7 BaO 0-9 K.sub.2 O 6-8.5 ZnO 0-10 Li.sub.2 O + Na.sub.2 O + K.sub.2 O 10-15 CaO + SrO + BaO + 8-18 ZnO B.sub.2 O.sub.3 9-12 Al.sub.2 O.sub.3 4.5-7 ______________________________________ with the proviso that the mole ratio (Li.sub.2 O+Na.sub.2 O+K.sub.2 O):(CaO+SrO+ZnO) is greater than 1.0 and ranges up to about 1.4.
Claims4
A glass frit composition essentially free from lead and cadmium exhibiting a linear coefficient of thermal expansion (25.degree.-300.degree. C.) of about 70-85.times.10.sup.-7 /.degree.C., good flow at temperatures between 900.degree.-1000.degree. C., a softening point of about 650.degree.-740.degree. C., and excellent resistance to attack by acetic acid and detergent consisting essentially, expressed in terms of weight percent on the oxide basis, of
- ______________________________________ SiO.sub.2 51-59 CaO 0-7 Li.sub.2 O 0-2 SrO 0-12 Na.sub.2 O 3.5-7 BaO 0-9 K.sub.2 O 6-8.5 ZnO 0-10 Li.sub.2 O + Na.sub.2 O + K.sub.2 O 10-15 CaO + SrO + BaO + 8-18 ZnO B.sub.2 O.sub.3 9-12 Al.sub.2 O.sub.3 4.5-7 ______________________________________
- with the proviso that the mole ratio (Li.sub.2 O+Na.sub.2 O+K.sub.2 O):(CaO+SrO+BaO+ZnO) is greater than 1.0 and ranges up to about 1.4.
A composite article consisting of a glass-ceramic body containing potassium fluorrichterite and cristobalite in amounts in excess of 10% by volume as essentially the sole crystal phases and an adherent glaze essentially free from lead and cadmium exhibiting a linear coefficient of thermal expansion (25.degree.-300.degree. C.) of about 70-85.times.10.sup.-7 /.degree.C., a softening point of about 650.degree.-740.degree. C., and excellent resistance to attack by acetic acid and detergent consisting essentially, expressed in terms of weight percent on the oxide basis, of
- ______________________________________ SiO.sub.2 51-59 CaO 0-7 Li.sub.2 O 0-2 SrO 0-12 Na.sub.2 O 3.5-7 BaO 0-9 K.sub.2 O 6-8.5 ZnO 0-10 Li.sub.2 O + Na.sub.2 O + K.sub.2 O 10-15 CaO + SrO + BaO + 8-18 ZnO B.sub.2 O.sub.3 9-12 Al.sub.2 O.sub.3 4.5-7 ______________________________________
- with the proviso that the mole ratio (Li.sub.2 O+Na.sub.2 O+K.sub.2 O):(CaO+SrO+ZnO) is greater than 1.0 and ranges up to about 1.4.
Dependencies are inferred from the claim text.