Compositions: coating or plastic – Coating or plastic compositions – Marking
Patent
1977-01-07
1978-04-11
Fisher, Richard V.
Compositions: coating or plastic
Coating or plastic compositions
Marking
65 32, 65 33, C03C 322, C03B 3200
Patent
active
040837270
ABSTRACT:
The instant invention relates to the production of glass-ceramic articles, wherein the predominant crystal phase is beta-quartz solid solution and/or beta-spodumene solid solution, but which have a thin, integral, tightly-bonded surface film containing crystals exhibiting the structure of magnetite. The preferred method of production for such articles requires three general steps. First, a glass article having a particular composition within the Li.sub.2 O--FeO--Al.sub.2 O.sub.3 --SiO.sub.2 field nucleated with TiO.sub.2 is heat treated in air or other oxidizing atmosphere to yield a glass-ceramic article through the crystallization in situ of beta-quartz solid solution and/or beta-spodumene solid solution crystals. Simultaneously during this heat treatment, a surface layer containing hematite is developed. Second, the glass-ceramic article is subjected to a hot acid bath. Third, the acid-washed article is heat treated in a H.sub.2 O-containing reducing atmosphere to convert the hematite crystals to magnetite. The resulting films demonstrate high coercive forces and saturation magnetization comparable to that of magnetite and other ceramic ferrite materials.
REFERENCES:
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patent: 3557576 (1971-01-01), Baum
patent: 3639113 (1972-02-01), Aslanova et al.
patent: 3790360 (1974-02-01), Kato et al.
patent: 3892904 (1975-07-01), Tanaka
patent: 3902881 (1975-09-01), Pirooz
patent: 3962514 (1976-06-01), Rittler
Andrus Ronald L.
Reade Richard F.
Corning Glass Works
Fisher Richard V.
Janes Jr. Clinton S.
Miga Frank W.
Patty, Jr. Clarence R.
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