Opal glasses having an apatite opacifying phase
AssigneeCorning Glass Works
InventorsJames E. Flannery, John L. Stempin, Dale R. Wexell
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Abstract
This invention is drawn to spontaneous opal glasses containing an apatite-type crystal opacifying phase and exhibiting a temperature interval between the emulsion and high temperature crystallization liquidi of at least 50.degree. C. which consist essentially, in weight percent on the oxide basis, of ______________________________________ Na.sub.2 O 7.5-11 B.sub.2 O.sub.3 2-4.5 K.sub.2 O 0-5 SiO.sub.2 57-65 Na.sub.2 O + K.sub.2 O .ltoreq.13 P.sub.2 O.sub.5 2-5.5 BaO 0-9.5 F 1.5-4 CaO 0-3 SrO 0-5 ZnO 0.4-5 MgO 0-2.5 Al.sub.2 O.sub.3 8-13 SrO + MgO 0-5 ______________________________________ CaO and/or SrO and/or BaO at least 2.5 mole %.
Claims3
A white spontaneous opal glass exhibiting a softening point of at least 710.degree. C., excellent chemical durability, a temperature interval between the high temperature crystallization liquidus and the emulsion liquidus of at least 50.degree. C., and containing as the predominant crystal phase at least one apatite-type crystal selected from the group of Ca.sub.5 F(PO.sub.4).sub.3, Sr.sub.5 F(PO.sub.4).sub.3, Ba.sub.5 F(PO.sub.4).sub.3, (Ca.sub.5-x Ba.sub.x)F(PO.sub.4).sub.3 solid solution, (Sr.sub.5-x Ba.sub.x)F(PO.sub.4).sub.3 solid solution, (Ca.sub.5-x Sr.sub.x)F(PO.sub.4).sub.3 solid solution, (Sr.sub.5-x Ca.sub.x)F(PO.sub.4).sub.3 solid solution, (Ba.sub.5-x Ca.sub.x)F(PO.sub.4).sub.3 solid solution, and (Ba.sub.5-x Sr.sub.x)F(PO.sub.4).sub.3 solid solution, said glass consisting essentially, expressed in terms of weight percent on the oxide basis, of
- ______________________________________ Na.sub.2 O 7.5-11 B.sub.2 O.sub.3 2-4.5 K.sub.2 O 0-5 SiO.sub.2 57-65 Na.sub.2 O + K.sub.2 O .ltoreq.13 P.sub.2 O.sub.5 2-5.5 BaO 0-9.5 F 1.5-4 CaO 0-3 SrO 0-5 ZnO 0.4-5 MgO 0-2.5 Al.sub.2 O.sub.3 8-13 SrO + MgO 0-5 ______________________________________
- CaO and/or SrO and/or BaO at least 2.5 mole %.
Dependencies are inferred from the claim text.