Glass-ceramic article

• US 4,755,488 A
• Filed: 10/22/1985
• Issued: 07/05/1988
• Est. Priority Date: 10/23/1984
• Status: Expired due to Fees

• Current Assignee: Nippon Sheet Glass Company Limited 8 4-Chome Doshomachi Higashi-Ku Osaka Japan
• Original Assignee: Nippon Sheet Glass Company Limited (Nippon Telegraph and Telephone Corporation)
• Inventors: Nagashima, Yukihito
• Primary Examiner(s): Bell, Mark L.
• Application Number:
  US06/791,158
• Time in Patent Office: 987 Days
• Field of Search: 501/7, 501/4, 65/30.13, 65/30.14
• US Class Current: 501/4
• CPC Class Codes: C03C 10/0027 containing SiO2, Al2O3, Li2O as main constituents
• CPC Class Codes: C03C 21/002 to perform ion-exchange between alkali ions C03C21/005 takes precedence

Abstract

A transparent glass-ceramic article of a unitary structure composed of an interior portion and an exterior portion, wherein the interior portion containing a crystalline phase comprises

(a) 55 to 75% by weight of SiO₂,

(b) 15 to 30% by weight Al₂ O₃,

(c) 2 to 6% by weight of Li₂ O

(d) 1 to 5% by weight of Na₂ O, and

(e) 2 to 9% by weight of TiO₂ +ZrO₂ P₂ O₅,

the total amount of the components (a) to (e) being 95 to 100 by weight, and wherein the exterior portion has the same glass composition as the interior portion but at least a part of Na⁺ in the exterior portion is exchanged with K⁺.

Claims

1. A transparent glass-ceramic article of a unitary structure composed of an interior portion and an exterior portion, wherein the interior portion containing a crystalline phase consisting essentially of

(a) 55 to 75% by weight of SiO₂,

(b) 15 to 30% by weight Al₂ O₃,

(c) 2 to 6% by weight of Li₂ O,

(d) 1.2-5% by weight of Na₂ O, and

(e) 2 to 9% by weight of TiO₂ +ZrO₂ +P₂ O₅,

the total amount of the components (a) to (e) being 95 to 100 by weight, and wherein the exterior portion has the same glass composition as the interior portion but at least a part of Na⁺ in the exterior portion is exchanged with K⁺.

2. The glass-ceramic article of claim 1 wherein the interior portion consisting essentially of (a) 60 to 72% by weight of SiO₂, (b) 18 to 26% by weight of Al₂ O₃, (c) 3 to 5% by weight of LiO₂, (d) 1.2 to 3% by weight of Na₂ O and (e) 3.5 to 9% by weight of TiO₂ +ZrO₂ +P₂ O₅.

3. The glass-ceramic article of claim 2 wherein the interior portion consisting essentially of (a) 64 to 68% by weight of SiO₂, (b) 21 to 24% by weight of Al₂ O₃, (c) 3.5 to 5% by weight of Li₂ O, (d) 1.2 to 2.5% by weight of Na₂ O and (e) 3.5 to 7.5% by weight of TiO₂ +ZrO₂ +P₂ O₅.

4. The glass-ceramic article of claim 1 wherein the crystalline phase is a beta-quartz solid solution or beta-spodumene.

5. The glass-ceramic article of claim 1 wherein the crystalline phase is a beta-quartz solid solution.

6. The glass-ceramic article of claim 1 wherein the component (e) is composed of 0 to 7.5% by weight of TiO₂, 0 to 7.5% by weight of ZrO₂ and 0 to 5% by weight of P₂ O₅.

7. The glass-ceramic article of claim 6 wherein the component (e) is composed of 1.5 to 5% by weight of TiO₂, 1.5 to 5% by weight of ZrO₂ and 0 to 5% by weight of P₂ O₅.

8. The glass-ceramic article of claim 7 wherein the component (e) is composed of 1.5 to 5% by weight of TiO₂, 1.5 to 3.5% by weight of ZrO₂ and 0 to 3% by weight of P₂ O₅.