A method of manufacturing glass ceramic articles such as glass ceramic plates for cooktops or fireplace windows is provided. The method facilitates the adjustment of a specific hue or a specific absorptivity of the glass ceramic in the visible spectral range. The method is based on the finding that the absorption of light by coloring agents which are appropriate for or present in glass ceramics can be attenuated during the ceramization process by adding substances that have a decoloring effect.

A cover glass is provided that includes a silica based glass ceramic with a thickness between 0.4 mm and 0.85 mm. The glass ceramic has a transmittance of more than 80% from 380 nm to 780 nm and a stress attribute selected from: an overall compressive stress (CS) of at least 250 MPa and at most 1500 MPa, a compressive stress at a depth of 30 μm (CS30) from one of the two faces of at least 160 MPa and at most 525 MPa, a depth of the compression layer (DoCL) of at least 0.2 times the thickness and less than 0.5 times the thickness, and any combinations thereof. The glass ceramic has at least one silica based crystal phase having in a near-surface layer a unit cell volume of at least 1% by volume larger than that of a core where the crystal phase has minimum stresses.

A bioactive glass-ceramic composition as defined herein. Also disclosed are methods of making and using the disclosed compositions.

A coated glass or glass ceramic substrate includes a substrate with a surface area and a coating on that surface area. The coating includes a glass matrix and IR-reflecting pigments. The IR-reflecting pigments have a TSR value of at least 20%, as determined according to ASTM G 173. The coating, at a wavelength of 1500 nm, exhibits a remission of at least 35%, as measured according to ISO 13468.

The present invention relates to a glass ceramic including crystals, and including, in mol % in terms of oxides: 65-75% of SiO.sub.2; 3-6% of Al.sub.2O.sub.3; 15-25% of Li.sub.2O; 0.2-4% of P.sub.2O.sub.5; 0.5-5% of ZrO.sub.2; and 0.01-0.5% of HfO.sub.2, in which the crystals include one or more kinds of crystals selected from the group consisting of β-spodumene crystals, petalite crystals, and eucryptite crystals.

The present invention provides a microcrystalline glass and microcrystalline glass product with excellent mechanical properties, microcrystalline glass product, the components of which, expressed in weight percent, contain: SiO.sub.2: 65 ∼80%; AI.sub.2O.sub.3: below 5%; Li.sub.2O: 10 ∼25%; ZrO.sub.2: 5 ∼15%; P.sub.2O.sub.5: 1 ∼8%. Through the reasonable component design, the microcrystalline glass product obtained by the present invention have excellent mechanical properties.

ZrO.sub.2-toughened glass ceramics having high molar fractions of tetragonal ZrO.sub.2 and fracture toughness value of greater than 1.8 MPa.Math.m.sup.1/2. The glass ceramic may also include also contain other secondary phases, including lithium silicates, that may be beneficial for toughening or for strengthening through an ion exchange process. Additional second phases may also decrease the coefficient of thermal expansion of the glass ceramic. A method of making such glass ceramics is also provided.

A three dimensional glass ceramic article with a thickness between 0.1 mm and 2 mm, having a dimensional precision control of less than or equal to ±0.1 mm. A method for forming a three dimensional glass ceramic article including placing a nucleated glass article into a mold, and heating the nucleated glass article to a crystallization temperature, where the nucleated glass article is in the mold during the heating. Then, holding the nucleated glass article at the crystallization temperature for a duration sufficient to crystallize the nucleated glass article and form a three dimensional glass ceramic article, where the nucleated glass article is in the mold during the holding, and removing the three dimensional glass ceramic article from the mold.

A transparent β-spodumene glass-ceramic is provided. The glass-ceramic includes a primary crystal phase including a β-spodumene solid solution, a secondary crystal phase including tetragonal ZrO.sub.2, and an amorphous phase. The glass-ceramic may be ion exchanged utilizing molten alkali nitrate salt baths. Methods for producing the glass-ceramic are also provided.

A glass-based article comprising a thickness t; a first clad layer having a first thickness t.sub.C1; a second clad layer having a first thickness t.sub.C2; and a core layer having a first thickness t.sub.o, which core layer is disposed between and bonded to the first and second clad layers. A first compressive stress region extends from a surface of the first clad layer to a first depth of compression DOC.sub.1. A second compressive stress region extends from a surface of the second clad layer to a second depth of compression DOC.sub.2. The first and second compressive stress regions comprise a maximum compressive stress greater than or equal to 500 MPa. A central tension region extends from DOC.sub.1 to DOC.sub.2 and has a maximum central tension CT greater than or equal to 250 MPa. A difference in flaw sizes that produce delayed fracture is less than or equal to 3 μm.