Peraluminious nepheline/kalsilite glass-ceramics

• US 4,310,595 A
• Filed: 10/31/1980
• Issued: 01/12/1982
• Est. Priority Date: 10/31/1980
• Status: Expired due to Term

• Current Assignee: Corning Glass Works Inc. (Corning Incorporated)
• Original Assignee: Corning Glass Works Inc. (Corning Incorporated)
• Inventors: Beall, George H., Pierson, Joseph E.
• Primary Examiner(s): Robinson, Ellis P.
• Application Number:
  US06/202,739
• Time in Patent Office: 438 Days
• Field of Search: 428/410, 428/332, 428/334, 428/325, 428/428, 65/33, 65/30.14, 65/30.13, 106/39.8
• US Class Current: 428/332
• CPC Class Codes: C03C 10/0018 containing SiO2, Al2O3 and monovalent metal oxide as main constituents
• CPC Class Codes: C03C 10/0036 containing SiO2, Al2O3 and a divalent metal oxide as main constituents
• CPC Class Codes: C03C 21/00 Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface
• CPC Class Codes: C03C 21/001 in liquid phase, e.g. molten salts, solutions
• CPC Class Codes: Y10T 428/252 Glass or ceramic [i.e., fired or glazed clay, cement, etc.] [porcelain, quartz, etc.]
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/263 Coating layer not in excess of 5 mils thick or equivalent
• CPC Class Codes: Y10T 428/315 Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

The present invention is concerned with glass-ceramic articles which are extremely resistant to impact and spontaneous delayed breakage, are capable of being sawn with a diamond wheel to a depth of over one-third the cross section thereof without breakage, and exhibit modulus of rupture values of at least 150,000 psi. The articles consist of a body portion and an integral surface compression layer having a depth of at least 0.005". The body portion consists essentially, in weight percent, of about 8-13% Na₂ O, 7-13% K₂ O, 30-36% Al₂ O₃, 35-43% SiO₂, and 6-10% RO₂, wherein RO₂ consists of 6-10% TiO₂ and 0-4% ZrO₂, wherein the molar ratio Al₂ O₃ :SiO₂ is >0.5 but <0.6 and the molar ratio K₂ O:Na₂ O is >1:3 but <1 and contains nepheline solid solution crystals corresponding to the formula Na_8-x K_x Al₈ Si₈ O₃₂, with x varying from 0.25-4.73, as the predominant crystal phase. The surface layer contains kalsilite as the predominant crystal phase and is produced by subjecting the base glass-ceramic article to an ion exchange reaction wherein K⁺ ions replace at least part of the Na⁺ ions in the nepheline solid solution crystals to convert those crystals to kalsilite.

Claims

1. A glass-ceramic article extremely resistant to impact and spontaneous delayed breakage, capable of being sawn with a diamond wheel to a depth of over one-third the cross section thereof without breakage, exhibiting a modulus of rupture of at least 150,000 psi, and wherein the crystal present therein have diameters of less than about 0.5 micron, said article consisting of a body portion and an integral surface compression layer having a thickness of at least 0.005", said body portion consisting essentially, expressed in weight percent on the oxide basis, of about 8-13% Na₂ O, 7-13% K₂ O, 30-36% Al₂ O₃, 35-43% SiO₂, and 6-10% RO₂, wherein RO₂ consists of 6-10% TiO₂ and 0-4% ZrO₂, wherein the molar ratio Al₂ O₃ :

SiO₂ is >

0.5 but <

0.6 and the molar ratio K₂ O;

Na₂ O is >

1;

3 but <

1, and containing nepheline solid solution crystals corresponding to the formula Na_8-x K_x Al₈ Si₈ O₃₂, with x varying from 0.25-4.73, as the predominant crystal phase, and said surface layer containing kalsilite as the predominant crystal phase.