.beta.-quartz-based glass-ceramics
AssigneeCorning Incorporated
InventorsGeorge H. Beall, Linda R. Pinckney
Life of this patent
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Abstract
Nanocrystalline glass-ceramic materials based on .beta.-quartz solid solution Mg-rich phases formed in the system SiO.sub.2 --Al.sub.2 O.sub.3 --MgO--Li.sub.2 O--TiO.sub.2 (ZnO, BaO, ZrO.sub.2, P.sub.2 O.sub.5). Articles made from the glass-ceramic materials exhibit a crystal phase assemblage of a fine-grained, microstructure which is predominantly .beta.-quartz, and at least one additional phase selected from enstatite and spinel, and having a composition which consists essentially of, in weight percent on the oxide basis, 40-65% SiO.sub.2, 10-14% Al.sub.2 O.sub.3, 5-25% MgO, 0.5-4% Li.sub.2 O, 5-15% TiO.sub.2, and up to 5% ZrO.sub.2, such that the sum of (TiO.sub.2 +ZrO.sub.2) is at least 9% The glass-ceramide article is particularly useful for memory disk applications.
Claims12
A glass-ceramic article exhibiting a crystal phase assemblage which is comprised of fine-grained, microstructures of .beta.-quartz and at least one phase selected from enstatite and spinel, the article having a composition which consists essentially of, in weight percent on the oxide basis, 40-65% SiO.sub.2, 10-40% Al.sub.2 O.sub.3, 5-25% MgO, 0.5-4% Li.sub.2 O, 5-15% TiO.sub.2, and up to 5% ZrO.sub.2, such that the sum (TiO.sub.2 +ZrO.sub.2) is at least 9%.
A method for making a glass-ceramic article which comprises the steps of
- a) melting a batch for a glass composition at least 92% of which consists essentially, expressed in terms of weight percent on the oxide basis, of 40-65% SiO.sub.2, 10-40% Al.sub.2 O.sub.3, 5-25% MgO, 0-10% ZnO, 5-15% TiO.sub.2, 0-5% ZrO.sub.2, and 0.5-4% Li.sub.2 O;
- b) heating the glass article to a temperature range of about 750-850.degree. C.;
- c) maintaining the temperature for a time sufficient to cause the article to obtain a high degree of nucleation;
- d) heating the glass article to a temperature range about 850-1100.degree.C.;
- and
- e) maintaining the temperature for a time sufficient to cause the article to crystallize in situ forming a crystallized glass article which exhibits crystal phase assemblage comprised predominantly of uniformly-sized, fine-grained, microstructures of .beta.-quartz and at least one phase selected from the group consisting of enstatite and spinel.
A rigid information disk for use in a magnetic memory storage device consisting essentially of a substrate with a coating of magnetic media on a surface thereof, wherein the substrate is comprised of a glass-ceramic material having a crystal phase assemblage comprised predominantly of fine-grained, microstructures .beta.-quartz and at least one phase selected from enstatite and spinel, the article having a composition which consists essentially of, in weight percent on the oxide basis, 40-65% SiO.sub.2, 10-40% Al.sub.2 O.sub.3, 5-25% MgO, 0.5-4% Li.sub.2 O, 5-15% TiO.sub.2, and 0-6% ZrO.sub.2 such that the sum of (TiO.sub.2 +ZrO.sub.2) is at least 9%.
Dependencies are inferred from the claim text.