Method for making glass-ceramic articles exhibiting high frangibility
- Big Flats, NY
- Corning, NY
- Horseheads, NY
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.
- Assignee:
- United States of America as represented by United States Energy (Washington, DC)
- Patent Number(s):
- US 3936287
- Application Number:
- 05/437,008
- OSTI ID:
- 862459
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
glass-ceramic
articles
exhibiting
frangibility
concerned
compositions
narrowly-delimited
mgo-al
-b
-sio
field
alpha-quartz
sapphirine
principal
crystal
phases
resulting
nucleation
combination
zro
contacting
lithium
elevated
temperature
replace
magnesium
-for-one
mg
basis
structures
providing
unitary
article
integral
surface
layer
phase
lithium-stuffed
beta-quartz
solid
solution
transformation
results
compressive
stresses
set
cooled
careful
control
composition
crystallization
treatment
parameters
replacement
reaction
tremendous
degree
stored
elastic
energy
developed
demonstrate
fractured
exhibit
undesirable
spontaneous
breakage
spalling
ceramic article
elevated temperature
surface layer
crystal structure
solid solution
ceramic articles
compressive stress
principal crystal
compressive stresses
glass-ceramic articles
crystal phase
/65/