U.S. patent application number 17/735055 was filed with the patent office on 2022-08-18 for inorganic composition article and crystallized glass.
The applicant listed for this patent is OHARA INC.. Invention is credited to NOZOMU ODA, KOHEI OGASAWARA, TOSHITAKA YAGI.
Application Number | 20220259094 17/735055 |
Document ID | / |
Family ID | 1000006307980 |
Filed Date | 2022-08-18 |
United States Patent
Application |
20220259094 |
Kind Code |
A1 |
OGASAWARA; KOHEI ; et
al. |
August 18, 2022 |
INORGANIC COMPOSITION ARTICLE AND CRYSTALLIZED GLASS
Abstract
To provide an inorganic composition article containing at least
one kind selected from .alpha.-cristobalite and
.alpha.-cristobalite solid solution as a main crystal phase, in
which by mass % in terms of oxide, a content of a SiO.sub.2
component is 50.0% to 75.0%, a content of a Li.sub.2O component is
3.0% to 10.0%, a content of an Al.sub.2O.sub.3 component is 5.0% or
more and less than 15.0%, and a total content of the
Al.sub.2O.sub.3 component and a ZrO.sub.2 component is 10.0% or
more, and a surface compressive stress value is 600 MPa or
more.
Inventors: |
OGASAWARA; KOHEI; (KANAGAWA,
JP) ; YAGI; TOSHITAKA; (KANAGAWA, JP) ; ODA;
NOZOMU; (KANAGAWA, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OHARA INC. |
KANAGAWA |
|
JP |
|
|
Family ID: |
1000006307980 |
Appl. No.: |
17/735055 |
Filed: |
May 2, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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17436612 |
Sep 6, 2021 |
|
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PCT/JP2020/009459 |
Mar 5, 2020 |
|
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17735055 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C03B 27/03 20130101;
C03C 10/0027 20130101; C03C 2204/00 20130101; C03C 21/002
20130101 |
International
Class: |
C03C 10/00 20060101
C03C010/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 6, 2019 |
JP |
2019-040205 |
Mar 6, 2019 |
JP |
2019-040206 |
Claims
1. An inorganic composition article containing at least one kind
selected from .alpha.-cristobalite and .alpha.-cristobalite solid
solution as a main crystal phase, wherein by mass % in terms of
oxide, a content of a SiO.sub.2 component is 50.0% to 75.0%, a
content of a Li.sub.2O component is 3.0% to 10.0%, a content of an
Al.sub.2O.sub.3 component is 5.0% or more and less than 15.0%, and
a total content of the Al.sub.2O.sub.3 component and a ZrO.sub.2
component is 10.0% or more, and a surface compressive stress value
is 600 MPa or more.
2. The inorganic composition article according to claim 1, wherein
by mass % in terms of oxide, a content of a ZrO.sub.2 component is
more than 0% and 10.0% or less, a content of a K.sub.2O component
is 0% to 10.0%, and a content of a P.sub.2O.sub.5 component is 0%
to 10.0%.
3. The inorganic composition article according to claim 1 or 2,
wherein by mass % in terms of oxide, a content of a Na.sub.2O
component is 0% to 10.0%, a content of a MgO component is 0% to
10.0%, a content of a CaO component is 0% to 10.0%, a content of a
SrO component is 0% to 10.0%, a content of a BaO component is 0% to
10.0%, a content of a ZnO component is 0% to 10.0%, and a content
of a Sb.sub.2O.sub.3 component is 0% to 3.0%.
4. The inorganic composition article according to any one of claims
1 to 2, wherein by mass % in terms of oxide, a content of a
Nb.sub.2O.sub.5 component is 0% to 10.0%, a content of a
Ta.sub.2O.sub.5 component is 0% to 10.0%, and a content of a
TiO.sub.2 component is 0% or more and less than 7.0%.
5. A crystallized glass containing at least one kind selected from
.alpha.-cristobalite and .alpha.-cristobalite solid solution as a
main crystal phase, wherein by mass % in terms of oxide, a content
of a SiO.sub.2 component is 50.0% to 75.0%, a content of a
Li.sub.2O component is 3.0% to 10.0%, a content of an
Al.sub.2O.sub.3 component is 5.0% or more and less than 15.0%, a
content of a ZrO.sub.2 component is more than 0% and 10.0% or less,
and a total content of the Al.sub.2O.sub.3 component and the
ZrO.sub.2 component is 10.0% or more.
6. The crystallized glass according to claim 5, wherein by mass %
in terms of oxide, a content of a K.sub.2O component is 0% to 5.0%,
and a content of a P.sub.2O.sub.5 component is 0% to 10.0%.
7. The crystallized glass according to claim 5 or 6, wherein by
mass % in terms of oxide, a content of a Na.sub.2O component is 0%
to 4.0%, a content of a MgO component is 0% to 4.0%, a content of a
CaO component is 0% to 4.0%, a content of a SrO component is 0% to
4.0%, a content of a BaO component is 0% to 5.0%, a content of a
ZnO component is 0% to 10.0%, and a content of a Sb.sub.2O.sub.3
component is 0% to 3.0%.
8. The crystallized glass according to any one of claims 5 to 6,
wherein by mass % in terms of oxide, a content of a Nb.sub.2O.sub.5
component is 0% to 5.0%, a content of a Ta.sub.2O.sub.5 component
is 0% to 6.0%, and a content of a TiO.sub.2 component is 0% or more
and less than 1.0%.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional application of Ser. No.
17/436,612 filed on Sep. 6, 2021, and entitled "INORGANIC
COMPOSITION ARTICLE AND CRYSTALLIZED GLASS", now pending, the
entire disclosures of which are incorporated herein by
reference.
FIELD OF THE DISCLOSURE
[0002] The present disclosure relates to an inorganic composition
article having a hard surface and relates to crystallized
glass.
BACKGROUND OF THE DISCLOSURE
[0003] It is expected that various types of inorganic materials
will be used as a cover glass or a housing for protecting a display
of a portable electronic device such as a smartphone or a tablet
PC, a protector for protecting a lens of an in-vehicle optical
device, an interior bezel, a console panel, a touch panel material,
a smart key, and the like. These devices are required to be used in
a harsher environment than an environment required for a hard disk
substrate, and there is an increasing demand for an inorganic
material having a higher hardness.
[0004] There is crystallized glass obtained by increasing the
strength of glass. The crystallized glass is obtained by
precipitating crystals inside of the glass, and is known to have
superior mechanical strength to amorphous glass.
[0005] Conventionally, a known method for increasing the strength
of glass includes chemical strengthening. When an alkaline
component existing in a surface layer of glass is subject to
exchange reaction with an alkaline component with a larger ionic
radius to form a compressive stress layer on the surface, it is
possible to suppress the growth of cracks and increase the
mechanical strength. To do this, it is necessary to obtain a
sufficiently high compressive stress value.
[0006] Patent Document 1 discloses an inorganic composition article
for an information recording medium that can be chemically
strengthened. Patent Document 1 states that an
.alpha.-cristobalite-based inorganic composition article may be
chemically strengthened and may be used as a high-strength material
substrate. However, crystallized glass for an information recording
medium represented by a substrate for a hard disk is not intended
for use in a harsh environment, and the surface compressive stress
value associated with chemical strengthening has not been
discussed.
PRIOR ART DOCUMENT
[0007] [Patent Document] [0008] [Patent Document 1] Japanese
Unexamined Patent Application Publication No. 2008-254984
SUMMARY OF THE DISCLOSURE
[0009] An object of the present disclosure is to provide an
inorganic composition article having a high surface hardness and to
provide crystallized glass.
[0010] The present disclosure provides the following.
[0011] (Configuration 1)
[0012] An inorganic composition article containing at least one
kind selected from .alpha.-cristobalite and .alpha.-cristobalite
solid solution as a main crystal phase, wherein
[0013] by mass % in terms of oxide,
[0014] a content of a SiO.sub.2 component is 50.0% to 75.0%,
[0015] a content of a Li.sub.2O component is 3.0% to 10.0%,
[0016] a content of an Al.sub.2O.sub.3 component is 5.0% or more
and less than 15.0%, and
[0017] a total content of the Al.sub.2O.sub.3 component and a
ZrO.sub.2 component is 10.0% or more, and
[0018] a surface compressive stress value is 600 MPa or more.
[0019] (Configuration 2)
[0020] The inorganic composition article according to Configuration
1, wherein by mass % in terms of oxide,
[0021] a content of a ZrO.sub.2 component is more than 0% and 10.0%
or less,
[0022] a content of a K.sub.2O component is 0% to 10.0%, and
[0023] a content of a P.sub.2O.sub.5 component is 0% to 10.0%.
[0024] (Configuration 3)
[0025] The inorganic composition article according to Configuration
1 or 2, wherein by mass % in terms of oxide,
[0026] a content of a Na.sub.2O component is 0% to 10.0%,
[0027] a content of a MgO component is 0% to 10.0%,
[0028] a content of a CaO component is 0% to 10.0%,
[0029] a content of a SrO component is 0% to 10.0%,
[0030] a content of a BaO component is 0% to 10.0%,
[0031] a content of a ZnO component is 0% to 10.0%, and
[0032] a content of a Sb.sub.2O.sub.3 component is 0% to 3.0%.
[0033] (Configuration 4)
[0034] The inorganic composition article according to any one of
Configurations 1 to 3, wherein by mass % in terms of oxide,
[0035] a content of a Nb.sub.2O.sub.5 component is 0% to 10.0%,
[0036] a content of a Ta.sub.2O.sub.5 component is 0% to 10.0%,
and
[0037] a content of a TiO.sub.2 component is 0% or more and less
than 7.0%.
[0038] (Configuration 5)
[0039] A crystallized glass containing at least one kind selected
from .alpha.-cristobalite and .alpha.-cristobalite solid solution
as a main crystal phase, wherein by mass % in terms of oxide,
[0040] a content of a SiO.sub.2 component is 50.0% to 75.0%,
[0041] a content of a Li.sub.2O component is 3.0% to 10.0%,
[0042] a content of an Al.sub.2O.sub.3 component is 5.0% or more
and less than 15.0%,
[0043] a content of a ZrO.sub.2 component is more than 0% and 10.0%
or less, and
[0044] a total content of the Al.sub.2O.sub.3 component and the
ZrO.sub.2 component is 10.0% or more.
[0045] (Configuration 6)
[0046] The crystallized glass according to Configuration 5, wherein
by mass % in terms of oxide,
[0047] a content of a K.sub.2O component is 0% to 5.0%, and
[0048] a content of a P.sub.2O.sub.5 component is 0% to 10.0%.
[0049] (Configuration 7)
[0050] The crystallized glass according to Configuration 5 or 6,
wherein by mass % in terms of oxide,
[0051] a content of a Na.sub.2O component is 0% to 4.0%,
[0052] a content of a MgO component is 0% to 4.0%,
[0053] a content of a CaO component is 0% to 4.0%,
[0054] a content of a SrO component is 0% to 4.0%,
[0055] a content of a BaO component is 0% to 5.0%,
[0056] a content of a ZnO component is 0% to 10.0%, and
[0057] a content of a Sb.sub.2O.sub.3 component is 0% to 3.0%.
[0058] (Configuration 8)
[0059] The crystallized glass according to any one of
Configurations 5 to 7, wherein by mass % in terms of oxide,
[0060] a content of a Nb.sub.2O.sub.5 component is 0% to 5.0%,
[0061] a content of a Ta.sub.2O.sub.5 component is 0% to 6.0%,
and
[0062] a content of a TiO.sub.2 component is 0% or more and less
than 1.0%.
[0063] According to the present disclosure, it is possible to
provide an inorganic composition article having a high surface
hardness and crystallized glass.
[0064] The inorganic composition article and the crystallized glass
according to the present disclosure may be used for a protective
member for a device or the like by taking advantage of the feature
of being an inorganic material having high strength. The inorganic
composition article and the crystallized glass according to the
present disclosure may be used as a cover glass or a housing of a
smartphone, a member of a portable electronic device such as a
tablet PC and a wearable terminal, and a member such as a
protective protector or a substrate for a head-up display, or the
like used in a transport aircraft such as a vehicle and an
airplane. The inorganic composition article and the crystallized
glass according to the present disclosure may be used for other
electronic devices and machinery, a building member, a member for a
solar panel, a member for a projector, and a cover glass
(windshield) for eyeglasses and a watch, for example.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0065] Embodiments and examples of an inorganic composition article
according to the present disclosure will be described below in
detail, but the present disclosure is not limited to the following
embodiments and examples, and may be implemented with appropriate
changes within the scope of the object of the present
disclosure.
[0066] The inorganic composition article according to the present
disclosure is an inorganic composition article containing at least
one kind selected from .alpha.-cristobalite and
.alpha.-cristobalite solid solution as a main crystal phase, in
which
[0067] by mass % in terms of oxide,
[0068] a content of a SiO.sub.2 component is 50.0% to 75.0%,
[0069] a content of a Li.sub.2O component is 3.0% to 10.0%,
[0070] a content of an Al.sub.2O.sub.3 component is 5.0% or more
and less than 15.0%, and
[0071] a total content of the Al.sub.2O.sub.3 component and a
ZrO.sub.2 component is 10.0% or more, and
[0072] a surface compressive stress value is 600 MPa or more.
[0073] When the inorganic composition article has the above main
crystal phase, composition, and compressive stress value, it is
possible to provide a hard inorganic composition article.
[0074] The "inorganic composition article" in the present
disclosure is composed of inorganic composition materials such as
glass, crystallized glass, ceramics, or a composite material
thereof. For example, an article obtained by shaping these
inorganic materials into a desired shape by processing or synthesis
through a chemical reaction corresponds to the article according to
the present disclosure. A green compact obtained by crushing the
inorganic materials and then pressurizing the same, and a sintered
body obtained by sintering the green compact, for example, also
corresponds to the article according to the present disclosure. The
shape of the article obtained here is not limited in smoothness,
curvature, size, and the like. Examples of the shape include a
plate-shaped substrate, a shaped body with a curvature, and a
three-dimensional structure having a complicated shape.
[0075] The crystallized glass according to the present disclosure
is crystallized glass containing at least one kind selected from
.alpha.-cristobalite and .alpha.-cristobalite solid solution as a
main crystal phase, in which by mass % in terms of oxide,
[0076] a content of a SiO.sub.2 component is 50.0% to 75.0%,
[0077] a content of a Li.sub.2O component is 3.0% to 10.0%,
[0078] a content of an Al.sub.2O.sub.3 component is 5.0% or more
and less than 15.0%,
[0079] a content of a ZrO.sub.2 component is more than 0% and 10.0%
or less, and
[0080] a total content of the Al.sub.2O.sub.3 component and the
ZrO.sub.2 component is 10.0% or more.
[0081] When the crystallized glass has the above main crystal phase
and composition, it is possible to provide a hard crystallized
glass having high compressive stress value on the surface.
[0082] Crystallized glass is also called glass-ceramics, and is a
material obtained by subjecting glass to heat treatment to
precipitate crystals inside the glass. The crystallized glass is a
material having a crystalline phase and a glass phase, and is
distinguished from an amorphous solid. Generally, the crystal phase
of the crystallized glass is determined by using a peak angle
appearing in an X-ray diffraction pattern of X-ray diffraction
analysis.
[0083] The inorganic composition article and the crystallized glass
according to the present disclosure (hereinafter, also simply
referred to as "inorganic composition article") will be described
below. The inorganic composition article is preferably strengthened
crystallized glass.
[0084] The inorganic composition article contains one or more kinds
selected from .alpha.-cristobalite and .alpha.-cristobalite solid
solution as the main crystal phase. The inorganic composition
article that precipitates these crystalline phases has high
mechanical strength.
[0085] Here, the "main crystal phase" as used herein corresponds to
a crystal phase contained in the largest amount in the inorganic
composition article determined from the peak of the X-ray
diffraction pattern.
[0086] As used herein, all the contents of each component are
expressed by mass % in terms of oxide unless otherwise specified.
Here, "in terms of oxide" means that, if it is assumed that all the
constitutional components of the inorganic composition article are
decomposed into oxides, when the total mass of the oxides is 100%
by mass, the amount of the oxide of each component contained in the
inorganic composition article is expressed in mass %. As used
herein, "A % to B %" represents A % or more and B % or less.
[0087] A SiO.sub.2 component is an essential component necessary
for constituting one or more kinds selected from
.alpha.-cristobalite and .alpha.-cristobalite solid solution.
Preferably, the upper limit of the SiO.sub.2 component is 75.0% or
less, less than 74.0%, less than 73.7%, less than 72.5%, or less
than 72.0%. Preferably, the lower limit thereof is 50.0% or more,
55.0% or more, 58.0% or more, 60.0% or more, 62.0% or more, or
64.0% or more.
[0088] A Li.sub.2O component is an important component for
improving the meltability of a raw inorganic composition, and if
the amount of the Li.sub.2O component is less than 3.0%, it is not
possible to obtain the above effect and thus, it is difficult to
melt raw glass, and if the amount exceeds 10.0%, an amount of
lithium disilicate crystals to be produced increases.
[0089] Preferably, the lower limit of the Li.sub.2O component is
3.0% or more, 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or
more, or 5.5% or more. Preferably, the upper limit thereof is 10.0%
or less, 9.0% or less, 8.5% or less, or 8.0% or less.
[0090] An Al.sub.2O.sub.3 component is a component suitable for
improving the mechanical strength of the inorganic composition
article. Preferably, the upper limit of the Al.sub.2O.sub.3
component is less than 15.0%, 14.5% or less, 14.0% or less, 13.5%
or less, or 13.0% or less. Preferably, the lower limit thereof is
5.0% or more, 5.5% or more, 5.8% or more, 6.0% or more, or 6.5% or
more.
[0091] A ZrO.sub.2 component is an optional component to be added
to improve the mechanical strength. Preferably, the upper limit of
the ZrO.sub.2 component is 10.0% or less, 9.5% or less, 9.0% or
less, 8.8% or less, or 8.5% or less. Preferably, the lower limit
thereof is more than 0%, 0.1% or more, 1.0% or more, 1.5% or more,
1.8% or more, or 2.0% or more.
[0092] If [Al.sub.2O.sub.3+ZrO.sub.2], which is the sum of the
contents of the Al.sub.2O.sub.3 component and the ZrO.sub.2
component, is large in amount, the compressive stress on the
surface increases when chemical strengthening, heat treatment
strengthening, or ion implantation strengthening is performed.
Preferably, the lower limit of [Al.sub.2O.sub.3+ZrO.sub.2] is 10.0%
or more, 10.5% or more, 11.0% or more, 12.0% or more, 13.0% or
more, or more than 13.5%.
[0093] On the other hand, preferably, the upper limit of
[Al.sub.2O.sub.3+ZrO.sub.2] is 22.0% or less, 21.0% or less, 20.0%
or less, or 19.0% or less.
[0094] The lower limit of the total contents of the SiO.sub.2
component, the Li.sub.2O component, the Al.sub.2O.sub.3 component,
and the ZrO.sub.2 component may be 75.0% or more, 80.0% or more,
83.0% or more, or 85.0% or more.
[0095] A P.sub.2O.sub.5 component is an optional component to be
added to act as a crystal nucleation agent for the inorganic
composition. Preferably, the upper limit of the P.sub.2O.sub.5
component is 10.0% or less, 9.0% or less, 8.0% or less, or 7.5% or
less. Preferably, the lower limit thereof may be 0% or more, 0.5%
or more, 1.0% or more, or 1.5% or more.
[0096] A K.sub.2O component is an optional component to be added to
improve the surface compressive stress. Preferably, the lower limit
of the K.sub.2O component may be 0% or more, 0.1% or more, 0.3% or
more, 0.5% or more, or 0.8% or more.
[0097] If the K.sub.2O component is contained in an excessive
amount, it may be difficult to precipitate crystals. Therefore,
preferably, the upper limit thereof may be 10.0% or less, 6.0% or
less, 5.0% or less, 4.0% or less, 3.5%, or 3.0% or less.
[0098] A Na.sub.2O component is an optional component to be added
to improve the surface compressive stress. If the Na.sub.2O
component is contained in an excessive amount, it may be difficult
to obtain a desired crystal phase. Preferably, the upper limit of
the Na.sub.2O component may be 10.0% or less, 5.0% or less, 4.0% or
less, 3.0% or less, or 2.5% or less.
[0099] MgO, CaO, SrO, BaO, and ZnO components are optional
components and improve the meltability of the inorganic
composition, but if these components are contained in an excessive
amount, the obtained crystals tend to be coarsened. Therefore,
preferably, the upper limit of the MgO component is 10.0% or less,
7.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, or 2.5% or
less. Preferably, the upper limit of the CaO component may be 10.0%
or less, 7.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, or
2.0% or less. Preferably, the upper limit of the SrO component may
be 10.0% or less, 7.0% or less, 4.0% or less, 3.0% or less, 2.5% or
less, or 2.3% or less. Preferably, the upper limit of the BaO
component is 10.0% or less, 8.0% or less, 7.0% or less, 6.0% or
less, 5.0% or less, or 4.0% or less. Preferably, the upper limit of
the ZnO component may be 10.0% or less, 9.0% or less, 8.8% or less,
8.5% or less, 8.0% or less, or 7.5% or less.
[0100] The total amount of the SrO and BaO components is preferably
less than 12.0%. More preferably, the upper limit thereof may be
less than 10.0%, less than 8.0%, less than 6.0%, or less than
4.5%.
[0101] As long as the effects of the present disclosure are not
impaired, the inorganic composition article may or may not contain
each of a Nb.sub.2O.sub.5 component, a Ta.sub.2O.sub.5 component,
and a TiO.sub.2 component. Preferably, the upper limit of the
Nb.sub.2O.sub.5 component may be 10.0% or less, 6.0% or less, 5.0%,
or 3.0%. Preferably, the upper limit of the Ta.sub.2O.sub.5
component may be 10.0% or less, 8.0%, 6.0%, or 4.0% or less.
Preferably, the upper limit of the TiO.sub.2 component may be less
than 7.0%, 5.0% or less, 3.0% or less, 2.0% or less, less than
1.0%, 0.5% or less, or 0.1% or less.
[0102] As long as the effect of the present disclosure is not
impaired, the inorganic composition article may or may not contain
each of a B.sub.2O.sub.3 component, a La.sub.2O.sub.3 component, a
Y.sub.2O.sub.3 component, a WO.sub.3 component, a TeO.sub.2
component, and a Bi.sub.2O.sub.3 component. The blending amount of
each of the components may be 0% to 2.0%, 0% or more and less than
2.0%, or 0% to 1.0%.
[0103] As long as the characteristics of the inorganic composition
article according to the present disclosure is not impaired, the
inorganic composition article may or may not contain other
components not described above. Examples of the other components
include metal components (including metal oxides thereof) such as
Gd, Yb, Lu, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo.
[0104] A Sb.sub.2O.sub.3 component may be contained as a glass
clarifying agent. The upper limit thereof may be preferably 3.0% or
less, more preferably 1.0% or less, still more preferably 0.6% or
less.
[0105] The inorganic composition article may or may not include a
SnO.sub.2 component, a CeO.sub.2 component, an As.sub.2O.sub.3
component, and one or more kinds selected from the group of F, NOx,
and SOx, in addition to the Sb.sub.2O.sub.3 component, as the glass
clarifying agent. It is noted that the upper limit of the content
of the clarifying agent is preferably 3.0% or less, more preferably
1.0% or less, and most preferably 0.6% or less.
[0106] On the other hand, there is a tendency to refrain from using
each component of Pb, Th, Tl, Os, Be, Cl, and Se, which are
considered in recent years as harmful chemical substances, and
therefore, preferably, these components are not substantially
contained.
[0107] On the surface of the inorganic composition article
according to the present disclosure, a compressive stress layer
having a compressive stress value CS (MPa) of 600 MPa or more is
formed. On the surface of the crystallized glass according to the
present disclosure, a compressive stress layer may be formed. The
compressive stress value of the compressive stress layer is
preferably 600 MPa or more, more preferably 650 MPa or more, still
more preferably 680 MPa or more, and particularly preferably 700
MPa or more. The upper limit thereof is, for example, 1400 MPa or
less, 1300 MPa or less, 1200 MPa or less, or 1100 MPa or less. If
the compressive stress layer has such a compressive stress value,
the growth of cracks is suppressed and the mechanical strength
increases.
[0108] The thickness of the compressive stress layer DOLzero
(.mu.m) is not limited because it depends on the thickness of the
inorganic composition article. For example, in a case of a
crystallized glass substrate having a thickness of 10 mm, the lower
limit of the thickness of the compressive stress layer may be 1
.mu.m or more, 30 .mu.m or more, 50 .mu.m or more, 70 .mu.m or
more, 100 .mu.m or more, 130 .mu.m or more, 150 .mu.m or more, 180
.mu.m or more, or 200 .mu.m or more.
[0109] For example, when the inorganic composition article is a
crystallized glass substrate, this article can be produced by the
following method. That is, raw materials are uniformly mixed so
that the above components satisfy a predetermined content range,
and melted and shaped to produce raw glass. Next, the raw glass is
crystallized to produce crystallized glass.
[0110] The raw glass may be treated by heat for precipitation of
crystals at a one-stage temperature or a two-stage temperature.
[0111] In the two-stage heat treatment, in a nucleation step, the
raw glass is firstly applied to heat treatment at a first
temperature, and after the nucleation step, in a crystal growth
step, the raw glass is applied to heat treatment at a second
temperature higher than that in the nucleation step.
[0112] The first temperature of the two-stage heat treatment may be
preferably 450.degree. C. to 750.degree. C., more preferably
500.degree. C. to 720.degree. C., and still more preferably
550.degree. C. to 680.degree. C. A retention time at the first
temperature is preferably 30 minutes to 2000 minutes, and more
preferably 180 minutes to 1440 minutes.
[0113] The second temperature of the two-stage heat treatment is
preferably 600.degree. C. to 800.degree. C., more preferably
650.degree. C. to 750.degree. C. A retention time at the second
temperature is preferably 30 minutes to 600 minutes, and more
preferably 60 minutes to 400 minutes.
[0114] In the one-stage heat treatment, the nucleation step and the
crystal growth step are continuously performed at the one-stage
temperature. Typically, the temperature is raised to a
predetermined heat treatment temperature, is maintained for a
certain period of time after reaching the predetermined heat
treatment temperature, and is then lowered.
[0115] When the heat treatment is performed at the one-stage
temperature, the heat treatment temperature is preferably
600.degree. C. to 800.degree. C., and more preferably 630.degree.
C. to 770.degree. C. A retention time at the heat treatment
temperature is preferably 30 minutes to 500 minutes, and more
preferably 60 minutes to 400 minutes.
[0116] From the crystallized glass, it is possible to produce a
glass shaped body by using, for example, grinding and polishing
means. It is possible to produce the crystallized glass substrate
by processing the glass shaped body into a thin plate.
[0117] An example of a method for forming the compressive stress
layer of the inorganic composition article and a method for forming
a compressive stress layer in crystallized glass having no
compressive stress layer includes a chemical strengthening method
in which an alkaline component existing in a surface layer of the
crystallized glass substrate is subject to exchange reaction with
an alkaline component with a larger ionic radius to form a
compressive stress layer on the surface layer. Other examples
include a heat strengthening method in which the crystallized glass
substrate is heated, and then is quenched, and an ion implantation
method in which ions are implanted into the surface layer of the
crystallized glass substrate.
[0118] The chemical strengthening method may be implemented
according to the following steps, for example. A crystallized glass
base material is contacted to or immersed in a molten salt of a
salt containing potassium or sodium, for example, potassium nitrate
(KNO.sub.3), sodium nitrate (NaNO.sub.3) or a mixed salt or a
complex salt thereof. The treatment of contacting or immersing the
crystallized glass base material to and in the molten salt
(chemical strengthening treatment) may be performed in one stage or
in two stages.
[0119] For example, in the case of the two-stage chemical
strengthening treatment, firstly, the crystallized glass base
material is contacted to or immersed in a sodium salt or a mixed
salt of potassium and sodium heated at 350.degree. C. to
550.degree. C. for 1 to 1440 minutes, preferably 90 to 500 minutes.
Subsequently, secondly, the resultant crystallized glass base
material is contacted to or immersed in a potassium salt or a mixed
salt of potassium and sodium heated at 350.degree. C. to
550.degree. C. for 1 to 1440 minutes, preferably 60 to 600
minutes.
[0120] In the case of the one-stage chemical strengthening
treatment, the crystallized glass base material is contacted to or
immersed in a salt containing potassium or sodium heated at
350.degree. C. to 550.degree. C. or a mixed salt thereof for 1 to
1440 minutes.
[0121] The chemical strengthening of the inorganic composition
article may be performed in one stage or in multiple stages, but in
order to efficiently increase the surface compressive stress and
increase the thickness of the compressive stress layer, it is
preferable to perform the two-stage strengthening treatment in
which strengthening with a molten salt of sodium is firstly
performed and then strengthening with a molten salt of potassium is
secondly performed.
[0122] The heat strengthening method is not particularly limited,
but, for example, the inorganic composition article base material
may be heated to 300.degree. C. to 600.degree. C., and thereafter,
be applied to rapid cooling such as water cooling and/or air
cooling to form the compressive stress layer by a temperature
difference between the surface and the inside of the glass
substrate. It is noted that when the heat strengthening method is
combined with the above chemical treatment method, it is possible
to effectively form the compressive stress layer.
[0123] The ion implantation method is not particularly limited,
but, for example, an arbitrary ion may be collided on the surface
of the inorganic composition article base material with an
acceleration energy and an acceleration voltage that would not
destroy the surface of the base material to implant the ions into
the surface of the base metal. Thereafter, when heat treatment is
applied to the resultant surface of the base material as necessary,
it is possible to form the compressive stress layer on the surface
in much the same manner as in the other methods.
EXAMPLES
Examples 1 to 28 and Comparative Examples 1 and 2
[0124] Raw materials such as oxides, hydroxides, carbonates,
nitrates, fluorides, chlorides, and metaphosphate compounds
corresponding to a raw material of each component of the
crystallized glass were selected, and the selected raw materials
were weighed and mixed uniformly to have the compositions described
in Tables 1 to 3.
[0125] Next, the mixed raw materials were injected into a platinum
crucible and melted in an electric furnace at 1300.degree. C. to
1600.degree. C. for 2 to 24 hours depending on the difficulty of
melting the glass composition. Subsequently, the molten glass was
stirred and homogenized, cast into the mold after the temperature
was lowered to 1000.degree. C. to 1450.degree. C., and the casted
glass was cooled slowly to prepare raw glass. In Examples 1 to 24
and Comparative Examples 1 and 2, the obtained raw glass was
crystallized by the two-stage heat treatment to prepare
crystallized glass. In the first stage, nucleation was performed at
the temperatures and for the time periods shown in "Nucleation
Conditions" in Tables 1 to 3, and in the second stage,
crystallization was performed at the temperature and for the time
periods shown in "Crystallization Conditions" in Tables 1 to 3. In
Examples 25 to 28, the raw glass was crystallized by the one-stage
heat treatment to prepare the crystallized glass. Nucleation and
crystallization were performed at the temperatures and for the time
periods shown in "Crystallization conditions" in Table 3.
[0126] The crystal phases of the crystallized glasses of the
Examples 1 to 28 and the Comparative Examples 1 and 2 were
determined from an angle of a peak appearing in the X-ray
diffraction pattern using an X-ray diffraction analyzer (D8
Discover manufactured by Bruker). When the X-ray diffraction
patterns of the crystallized glasses of the Examples 1 to 28 and
the Comparative Examples 1 and 2 were seen, all the main peaks
(peaks with the highest intensity and the largest peak area) were
observed at positions corresponding to the peak pattern of
.alpha.-cristobalite and/or .alpha.-cristobalite solid solution,
and thus, it was determined that all the .alpha.-cristobalite and
the .alpha.-cristobalite solid solution were precipitated as the
main crystal phase.
[0127] The produced crystallized glass was cut and ground, and the
opposing sides of the resultant crystallized glass was further
polished in parallel to achieve a thickness of 10 mm to obtain a
crystallized glass substrate. Next, in the Examples 1 to 23, 25,
and 26, a chemically strengthened crystallized glass substrate was
obtained by applying the two-stage strengthening to the
crystallized glass substrate serving as a base material.
Specifically, the crystallized glass substrate was immersed in the
NaNO.sub.3 molten salt at the temperatures and for the time periods
shown in Tables 1 to 3 (first stage), and thereafter, the resultant
crystallized glass substrate was immersed in the KNO.sub.3 molten
salt at the temperatures and for the time periods shown in Tables 1
to 3 (second stage). The substrates obtained in the Example 24 and
the Comparative Examples 1 and 2 were subject to the one-stage
strengthening through immersion in KNO.sub.3 molten salt at the
temperatures and for the time periods shown in Table 3. The
strengthened substrates of the Comparative Examples 1 and 2 are
chemically strengthened crystallized glass substrates corresponding
to Examples 25 and 27 described in Patent Document 1. The
substrates obtained in the Examples 27 and 28 were subject to the
one-stage strengthening through immersion in the NaNO.sub.3 molten
salt at the temperatures and for the time periods shown in Table
3.
[0128] The compressive stress value (CS) on the surface of the
strengthened crystallized glass thus obtained was measured. In the
Examples 1 to 26 and the Comparative Examples 1 and 2, the
compressive stress value was measured by using a glass surface
stress meter FSM-6000LE series manufactured by Orihara
Manufacturing Co., LTD, and in the Examples 27 and 28, the
compressive stress value was measured by using a scattered light
photoelastic stress meter SLP-1000. As shown in Tables 1 to 3, in
the FSM-6000LE series, in measuring the compressive stress value,
the light source of the stress meter was selected between a
wavelength of 596 nm and 365 nm according to the strengthening
depth. In the SLP-1000, the compressive stress value was measured
by using a light source having a wavelength of 640 nm.
[0129] The values shown in Tables 1 to 3 were employed for values
of the refractive index, which are the CS measurement conditions.
The value of the refractive index of the wavelength (640 nm, 596
nm, or 365 nm) of the light source used for the measurement was
employed for the refractive index employed for the CS measurement.
It is noted that the value of the refractive index at a
predetermined wavelength was calculated by using a quadratic
approximation expression from the measured values of the refractive
index at the wavelengths of a C-line, a d-line, an F-line, and a
g-line according to the V-block method specified in JIS B 7071-2:
2018.
[0130] The values shown in Tables 1 to 3 were employed for the
values of the photoelastic constants, which are the CS measurement
conditions. The value of the photoelastic constant of the
wavelength (640 nm, 596 nm, or 365 nm) of the light source used for
the measurement was employed for the photoelastic constant employed
for the CS measurement. It is noted that the photoelastic constants
at wavelengths of 640 nm, 596 nm, or 365 nm were calculated by
using a quadratic approximation expression from the measured values
of the photoelastic constants at a wavelength of 435.8 nm, a
wavelength of 546.1 nm, and a wavelength of 643.9 nm.
[0131] In a method of measuring the photoelastic constant (.beta.),
the opposing sides of a sample shape were polished to form a disk
with a diameter of 25 mm and a thickness of 8 mm, a compressive
load was applied to the disk in a predetermined direction, the
optical path difference occurring in the center of the glass was
measured, and the relational expression of .delta.=.beta.dF was
used. In the above expression, .delta.(nm) denotes the optical path
difference, d(cm) denotes the glass thickness, and F(MPa) denotes
the stress.
[0132] In the measurement of the depth DOLzero (.mu.m) (also called
stress depth) when the compressive stress of the compressive stress
layer is 0 MPa, the sensitivity of the device differs depending on
the depth of DOLzero (.mu.m), and thus, the measurement device was
selected depending on the depth.
[0133] In measuring the depth of the Examples 1 to 23 and 25 to 28,
a scattered light photoelastic stress meter SLP-1000 was used, and
for the Example 24 and the Comparative Examples 1 and 2, a glass
surface stress meter FSM-6000LE series manufactured by Orihara
Manufacturing Co., LTD was used for measurement. The wavelength of
the measurement light source, the refractive index of the sample,
and the photoelastic constant were calculated by using the values
shown in Tables. It is noted that when DOLzero (.mu.m) exceeds 500
.mu.m, the depth cannot be measured by the above measuring device,
and thus, >500 was stated in Table 2.
[0134] The results are shown in Tables 1 to 3. From Tables 1 to 3,
it is seen that the inorganic composition article (crystallized
glass) according to the present disclosure has a compressive stress
layer having a high CS on the surface, and thus, the surface is
hard.
TABLE-US-00001 TABLE 1 Composition (mass %) Ex. 1 Ex. 2 Ex. 3 Ex. 4
Ex. 5 SiO.sub.2 68.50 66.80 65.70 65.57 66.80 Li.sub.2O 7.00 7.00
7.00 6.80 6.00 Na.sub.2O 2.00 K.sub.2O 2.00 2.00 2.00 1.40 1.00
Al.sub.2O.sub.3 7.50 7.50 7.50 7.20 7.50 P.sub.2O.sub.5 2.00 2.00
2.00 2.00 2.00 MgO 0.70 0.40 0.50 0.25 0.40 CaO SrO BaO 0.72 0.72
0.72 3.40 0.72 ZnO 6.50 6.50 6.50 6.40 6.50 ZrO.sub.2 5.00 5.00
5.00 4.90 5.00 Nb.sub.2O.sub.5 2.00 2.00 2.00 TiO.sub.2
Ta.sub.2O.sub.5 3.00 Sb.sub.2O.sub.3 0.08 0.08 0.08 0.08 0.08 Total
100.0 100.0 100.0 100.0 100.0 Al.sub.2O.sub.3 + ZrO.sub.2 12.5 12.5
12.5 12.1 12.5 Crystallization Nucleation Temperature 600 600 600
600 600 Conditions Conditions (.degree. C.) Retention time 5 5 5 5
5 (h) Crystallization Temperature 700 690 700 690 690 Conditions
(.degree. C.) Retention time 5 5 5 5 5 (h) Strengthening First
stage Temperature 420 420 420 420 420 Conditions (NaNO.sub.3)
(.degree. C.) Strengthening Retention time 4 4 4 4 4 (h) Second
stage Temperature 420 420 420 420 420 (KNO.sub.3) (.degree. C.)
Strengthening Retention time 2 2 2 2 2 (h) CS Measuring device
FSM6000LE FSM6000LE FSM6000LE FSM6000LE FSM6000LE measurement
Measurement light source 596 596 596 596 596 Conditions Wavelength
(nm) Refractive index n 1.528 1.538 1.539 1.541 1.535 Photoelastic
constant 30.3 31.2 31.2 31.2 31.2 (nm/cm/MPa) DOLzero Measuring
device SLP-1000 SLP-1000 SLP-1000 SLP-1000 SLP-1000 Measurement
Measurement light source 640 640 640 640 640 conditions Wavelength
(nm) Refractive index n 1.526 1.536 1.536 1.538 1.532 Photoelastic
constant 30.0 31.1 31.1 31.1 31.1 (nm/cm/MPa) CS(MPa) 734 719 745
700 823 DOLzero(.mu.m) 280 284 313 247 405 Composition (mass %) Ex.
6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 SiO.sub.2 71.02 69.52 67.42 67.42 68.02
Li.sub.2O 7.00 7.00 7.00 7.00 7.40 Na.sub.2O K.sub.2O 1.50 1.50
1.50 1.50 1.50 Al.sub.2O.sub.3 9.00 10.50 12.20 12.20 10.00
P.sub.2O.sub.5 2.40 2.40 2.00 2.00 2.00 MgO 2.00 2.00 0.30 0.30
0.50 CaO SrO 0.50 0.50 BaO 0.50 0.50 ZnO 2.00 2.00 4.00 4.00 2.50
ZrO.sub.2 4.00 4.00 5.50 5.50 8.00 Nb.sub.2O.sub.5 TiO.sub.2
Ta.sub.2O.sub.5 Sb.sub.2O.sub.3 0.08 0.08 0.08 0.08 0.08 Total
100.0 100.0 100.0 100.0 100.0 Al.sub.2O.sub.3 + ZrO.sub.2 13.0 14.5
17.7 17.7 18.0 Crystallization Nucleation Temperature 600 600 600
600 600 Conditions Conditions (.degree. C.) Retention time 5 5 5 5
5 (h) Crystallization Temperature 690 690 690 705 690 Conditions
(.degree. C.) Retention time 5 5 5 5 5 (h) Strengthening First
stage Temperature 420 420 420 420 420 Conditions (NaNO.sub.3)
(.degree. C.) Strengthening Retention time 4 4 4 4 4 (h) Second
stage Temperature 420 420 420 400 420 (KNO.sub.3) (.degree. C.)
Strengthening Retention time 2 2 2 2 2 (h) CS Measuring device
FSM6000LE FSM6000LE FSM6000LE FSM6000LE FSM6000LE measurement
Measurement light source 596 596 365 365 365 Conditions Wavelength
(nm) Refractive index n 1.523 1.523 1.549 1.549 1.553 Photoelastic
constant 29.2 29.2 34.0 34.0 34.0 (nm/cm/MPa) DOLzero Measuring
device SLP-1000 SLP-1000 SLP-1000 SLP-1000 SLP-1000 Measurement
Measurement light source 640 640 640 640 640 conditions Wavelength
(nm) Refractive index n 1.520 1.520 1.526 1.526 1.532 Photoelastic
constant 28.7 28.7 30.0 30.0 30.0 (nm/cm/MPa) CS(MPa) 760 803 910
904 920 DOLzero(.mu.m) 334 322 286 260 258
TABLE-US-00002 TABLE 2 Composition (mass %) Ex. 11 Ex. 12 Ex. 13
Ex. 14 Ex. 15 SiO.sub.2 67.82 68.92 66.42 66.42 66.11 Li.sub.2O
7.20 7.50 6.90 6.80 6.76 Na.sub.2O K.sub.2O 1.50 2.00 1.50 1.53
1.52 Al.sub.2O.sub.3 10.50 10.50 11.80 11.01 11.43 P.sub.2O.sub.5
2.00 2.00 5.00 6.70 6.67 MgO 0.40 1.00 0.30 0.29 0.29 CaO SrO 2.00
BaO ZnO 2.50 3.00 2.39 2.38 ZrO.sub.2 8.00 6.00 5.00 4.79 4.76
Nb.sub.2O.sub.5 TiO.sub.2 Ta.sub.2O.sub.5 Sb.sub.2O.sub.3 0.08 0.08
0.08 0.08 0.08 Total 100.0 100.0 100.0 100.0 100.0 Al.sub.2O.sub.3
+ ZrO.sub.2 18.5 16.5 16.8 15.8 16.2 Crystallization Nucleation
Temperature 600 600 600 600 600 Conditions Conditions (.degree. C.)
Retention time 5 5 5 5 5 (h) Crystallization Temperature 690 675
720 720 720 Conditions (.degree. C.) Retention time 5 5 5 5 5 (h)
Strengthening First stage Temperature 420 420 420 420 420
Conditions (NaNO.sub.3) (.degree. C.) Strengthening Retention time
4 4 4 4 4 conditions (h) Second stage Temperature 420 420 420 420
420 (KNO.sub.3) (.degree. C.) Strengthening Retention time 2 5 4 4
4 conditions (h) CS Measuring device FSM6000LE FSM6000LE FSM6000LE
FSM6000LE FSM6000LE measurement Measurement light source 365 365
596 596 596 Conditions Wavelength (nm) Refractive index n 1.553
1.547 1.521 1.516 1.514 Photoelastic constant 34.0 34.0 30.3 30.3
30.3 (nm/cm/MPa) DOLzero Measuring device SLP-1000 SLP-1000
SLP-1000 SLP-1000 SLP-1000 Measurement Measurement light source 640
640 640 640 640 conditions Wavelength (nm) Refractive index n 1.532
1.525 1.519 1.513 1.511 Photoelastic constant 30.0 30.0 30.0 30.0
30.0 (nm/cm/MPa) CS(MPa) 939 710 833 728 686 DOLzero(.mu.m) 262 267
>500 >500 >500 Composition (mass %) Ex. 16 Ex. 17 Ex. 18
Ex. 19 Ex. 20 SiO.sub.2 66.70 66.10 66.75 65.66 65.92 Li.sub.2O
6.20 7.20 6.93 7.14 7.00 Na.sub.2O K.sub.2O 1.90 1.50 1.48 1.53
1.50 Al.sub.2O.sub.3 8.10 12.50 12.08 12.44 12.20 P.sub.2O.sub.5
2.00 2.10 1.98 2.04 2.00 MgO 2.00 0.82 0.30 1.02 0.80 CaO 0.99 0.41
1.00 SrO 1.70 BaO 2.50 ZnO 6.00 4.10 3.96 4.08 4.00 ZrO.sub.2 2.40
5.60 5.45 5.60 5.50 Nb.sub.2O.sub.5 TiO.sub.2 Ta.sub.2O.sub.5
Sb.sub.2O.sub.3 0.50 0.08 0.08 0.08 0.08 Total 100.0 100.0 100.0
100.0 100.0 Al.sub.2O.sub.3 + ZrO.sub.2 10.5 18.1 17.5 18.0 17.7
Crystallization Nucleation Temperature 600 600 600 600 600
Conditions Conditions (.degree. C.) Retention time 5 5 5 5 5 (h)
Crystallization Temperature 690 700 690 700 700 Conditions
(.degree. C.) Retention time 5 5 5 5 5 (h) Strengthening First
stage Temperature 420 420 420 400 400 Conditions (NaNO.sub.3)
(.degree. C.) Strengthening Retention time 4 6 6 2.5 2.5 conditions
(h) Second stage Temperature 420 400 400 390 390 (KNO.sub.3)
(.degree. C.) Strengthening Retention time 4 2 2 3 3 conditions (h)
CS Measuring device FSM6000LE FSM6000LE FSM6000LE FSM6000LE
FSM6000LE measurement Measurement light source 596 596 596 596 596
Conditions Wavelength (nm) Refractive index n 1.528 1.531 1.532
1.533 1.533 Photoelastic constant 30.3 30.3 30.3 29.6 29.6
(nm/cm/MPa) DOLzero Measuring device SLP-1000 SLP-1000 SLP-1000
SLP-1000 SLP-1000 Measurement Measurement light source 640 640 640
640 640 conditions Wavelength (nm) Refractive index n 1.525 1.529
1.529 1.530 1.530 Photoelastic constant 30.0 30.0 30.0 29.2 29.2
(nm/cm/MPa) CS(MPa) 700 853 881 860 926 DOLzero(.mu.m) 221 323 306
283 275
TABLE-US-00003 TABLE 3 Composition (mass %) Ex. 21 Ex. 22 Ex. 23
Ex. 24 Ex. 25 SiO.sub.2 64.20 65.47 65.58 65.72 61.62 Li.sub.2O
6.97 7.42 7.24 7.28 6.30 Na.sub.2O K.sub.2O 1.50 1.52 1.55 1.50
1.50 Al.sub.2O.sub.3 12.10 12.40 12.62 12.16 6.70 P.sub.2O.sub.5
2.60 2.03 2.07 1.99 2.70 MgO 1.10 1.02 1.03 0.80 CaO 1.25 0.40 1.00
SrO BaO 2.60 ZnO 4.60 4.07 4.14 3.99 4.50 ZrO.sub.2 5.60 5.59 5.69
5.48 5.50 Nb.sub.2O.sub.5 2.50 TiO.sub.2 Ta.sub.2O.sub.5 6.00
Sb.sub.2O.sub.3 0.08 0.08 0.08 0.08 0.08 Total 100.0 100.0 100.0
100.0 100.0 Al.sub.2O.sub.3 + ZrO.sub.2 17.7 18.0 18.3 17.6 12.2
Crystallization Nucleation Temperature 600 600 600 600 --
Conditions Conditions (.degree. C.) Retention time 5 5 5 5 -- (h)
Crystallization Temperature 700 700 720 700 720 Conditions
(.degree. C.) Retention time 5 5 5 5 5 (h) Strengthening First
stage Temperature 400 400 400 -- 420 Conditions (NaNO.sub.3)
(.degree. C.) Strengthening Retention time 2.5 4 4 -- 4 conditions
(h) Second stage Temperature 390 400 400 380 380 (KNO.sub.3)
(.degree. C.) Strengthening Retention time 3 2 2 5 3 (h) CS
Measuring device FSM6000LE FSM6000LE FSM6000LE FSM6000LE FSM6000LE
measurement Measurement light source 596 596 596 596 365 Conditions
Wavelength (nm) Refractive index n 1.536 1.535 1.533 1.533 1.576
Photoelastic constant 29.6 30.3 30.3 30.3 34.0 (nm/cm/MPa) DOLzero
Measuring device SLP-1000 SLP-1000 SLP-1000 FSM6000LE SLP-1000
Measurement Measurement light source 640 640 640 596 640 conditions
Wavelength (nm) Refractive index n 1.533 1.532 1.530 1.533 1.552
Photoelastic constant 29.2 30.0 30.0 30.3 31.1 (nm/cm/MPa) CS(MPa)
958 895 893 1008 869 DOLzero(.mu.m) 257 235 176 4 184 Com. Com.
Composition (mass %) Ex. 26 Ex. 27 Ex. 28 Ex. 1 Ex. 2 SiO.sub.2
67.42 68.00 67.42 67.30 69.50 Li.sub.2O 7.00 7.00 7.00 6.20 7.00
Na.sub.2O K.sub.2O 1.00 0.50 1.00 2.00 2.00 Al.sub.2O.sub.3 12.20
13.80 12.20 7.40 7.00 P.sub.2O.sub.5 2.00 2.50 2.00 2.00 2.20 MgO
0.30 0.50 0.30 2.00 1.70 CaO SrO 1.70 1.00 BaO 2.50 1.60 ZnO 3.00
2.52 3.00 6.00 2.80 ZrO.sub.2 7.00 5.10 7.00 2.40 2.00
Nb.sub.2O.sub.5 TiO.sub.2 3.00 Ta.sub.2O.sub.5 Sb.sub.2O.sub.3 0.08
0.08 0.08 0.50 0.20 Total 100.0 100.0 100.0 100.0 100.0
Al.sub.2O.sub.3 + ZrO.sub.2 19.2 18.9 19.2 9.8 9.0 Crystallization
Nucleation Temperature -- -- -- 600 600 Conditions Conditions
(.degree. C.) Retention time -- -- -- 5 5 (h) Crystallization
Temperature 720 720 720 690 670 Conditions (.degree. C.) Retention
time 5 5 5 5 5 (h) Strengthening First stage Temperature 420 420
420 -- -- Conditions (NaNO.sub.3) (.degree. C.) Strengthening
Retention time 4 1 1 -- -- conditions (h) Second stage Temperature
380 -- -- 450 450 (KNO.sub.3) (.degree. C.) Strengthening Retention
time 3 -- -- 12 12 (h) CS Measuring device FSM6000LE SLP-1000
SLP-1000 FSM6000LE FSM6000LE measurement Measurement light source
596 640 640 596 596 Conditions Wavelength (nm) Refractive index n
1.533 1.524 1.531 1.530 1.534 Photoelastic constant 29.6 29.2 29.2
30.3 30.3 (nm/cm/MPa) DOLzero Measuring device SLP-1000 SLP-1000
SLP-1000 FSM6000LE FSM6000LE Measurement Measurement light source
640 640 640 596 596 conditions Wavelength (nm) Refractive index n
1.531 1.524 1.531 1.530 1.534 Photoelastic constant 29.2 29.2 29.2
30.3 30.3 (nm/cm/MPa) CS(MPa) 1002 628 646 573 529 DOLzero(.mu.m)
261 112 114 24 26
[0135] Although some embodiments and/or examples of the present
disclosure are described above in detail, those skilled in the art
may easily apply many modifications to these exemplary embodiments
and/or examples without substantial departure from the novel
teachings and effects of the present disclosure. Therefore, these
modifications are within the scope of the present disclosure.
[0136] All the contents of the literature described in the
specification are incorporated herein.
* * * * *