Glass manufacturing – Processes – With chemically reactive treatment of glass preform
Patent
1974-01-28
1976-02-03
Bashore, S. Leon
Glass manufacturing
Processes
With chemically reactive treatment of glass preform
65 33, C03c 1500, C03b 2900
Patent
active
039362876
ABSTRACT:
This invention is concerned with glass-ceramic articles having compositions within a very narrowly-delimited area of the MgO-Al.sub.2 O.sub.3 -B.sub.2 O.sub.3 -SiO.sub.2 field and having alpha-quartz and sapphirine as the principal crystal phases, resulting from nucleation through a combination of TiO.sub.2 and ZrO.sub.2. Upon contacting such articles with lithium ions at an elevated temperature, said lithium ions will replace magnesium ions on a two Li.sup.+-for-one Mg.sup..sup.+2 basis within the crystal structures, thereby providing a unitary glass-ceramic article having an integral surface layer wherein the principal crystal phase is a lithium-stuffed beta-quartz solid solution. That transformation of crystal phases results in compressive stresses being set up within the surface layer as the articles are cooled. Through the careful control of composition, crystallization treatment, and the parameters of the replacement reaction in the crystal structures, a tremendous degree of stored elastic energy can be developed within the articles such that they will demonstrate frangibility when fractured but will not exhibit undesirable spontaneous breakage and/or spalling.
REFERENCES:
patent: 3485644 (1969-12-01), Shonebarger
patent: 3486963 (1969-12-01), Smith
patent: 3573077 (1971-03-01), Beal et al.
patent: 3585054 (1971-06-01), Karstetter
patent: 3637453 (1972-01-01), Simmons
Beall George H.
Brydges, III. William T.
Ference Joseph
Kozlowski Theodore R.
Bashore S. Leon
Janes Jr. Clinton S.
Miga Frank W.
Patty, Jr. Clarence R.
The United States of America as represented by the United States
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