An opaque gahnite-spinel glass ceramic is provided. The glass ceramic includes a first crystal phase including (Mg.sub.xZn.sub.1-x)Al.sub.2O.sub.4 where x is less than 1 and a second crystal phase includes at least one of tetragonal ZrO.sub.2, MgTa.sub.2O.sub.6, mullite, and cordierite. The glass ceramic has a Young's modulus greater than or equal to 90 GPa, and has a hardness greater than or equal to 7.5 GPa. The glass ceramic may be ion exchanged. Methods for producing the glass ceramic are also provided.

A glass-ceramic article that includes an article having a glass-ceramic composition, the composition including: SiO.sub.2 from about 45% to about 65%, Al.sub.2O.sub.3 from about 14% to about 28%, TiO.sub.2 from about 2% to about 4%, ZrO.sub.2 from about 3% to about 4.5%, MgO from about 4.5% to about 12%, and ZnO from about 0.1 to about 4% (by weight of oxide).
The article can include a coefficient of thermal expansion (CTE) of about 20×10.sup.−7 K.sup.−1 to about 160×10.sup.−7 K.sup.−1, as measured over a temperature range from 25° C. to 300° C.

A fitout article or article of equipment for a kitchen or laboratory is provided. The article has a lighting and separating element. The separating element in a region of the lighting element has light transmittance of at least 0.1% and less than 12%. The lighting element in the interior emits light that passes through the separating element and to the exterior. The separating element has a glass or glass-ceramic substrate having a CTE of −6 to 6 ppm/K and has a colour locus in the CIELAB colour space with the coordinates L* of 20 to 40, a* of −6 to 6 and b* of −6 to 6. D65 standard illuminant light, after passing through the separating element, is within a white region W1 determined in the chromaticity diagram CIExyY−2° by the following coordinates: TABLE-US-00001 White region W1 x y 0.27 0.21 0.22 0.25 0.32 0.37 0.45 0.45 0.47 0.34 0.36  0.29.

A glass-ceramic article includes 50 mol. % to 80 mol. % SiO.sub.2; 10 mol. % to 25 mol. % Al.sub.2O.sub.3; 5 mol. % to 20 mol. % MgO; 0 mol. % to 10 mol. % Li.sub.2O; and 1 mol. % to 3 mol. % of a nucleating agent. The nucleating agent is selected from the group consisting of ZrO.sub.2, TiO.sub.2, SnO.sub.2, HfO.sub.2, Ta.sub.2O.sub.5, Nb.sub.2O.sub.5, Y.sub.2O.sub.3, and combinations thereof. The nucleating agent may comprise greater than or equal to 50% ZrO.sub.2 and less than 50% of at least one compound selected from the group consisting of TiO.sub.2, SnO.sub.2, HfO.sub.2, Ta.sub.2O.sub.5, Nb.sub.2O.sub.5, Y.sub.2O.sub.3, and combinations thereof. The glass-ceramic article may have a molar ratio of MgO to Li.sub.2O of greater than or equal to 1:1. The glass-ceramic article may satisfy the relationship 0.85≤(MgO (mol %)+Li.sub.2O (mol %))/Al.sub.2O.sub.3 (mol %)≤1.2. The glass-ceramic article may comprise a crystalline phase comprising hexagonal stuffed β-quartz and glass.

The present invention relates to glass-ceramic/silver composite precursor compositions in the form of powders, and to glass-ceramics/silver composite materials produced therefrom. Such materials find particular use as interconnect materials for high temperature electrochemical conversion devices such as solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs).

The present application provides transparent glass-ceramics of β-quartz of composition containing a small content of lithium, articles constituted at least in part of said glass-ceramics, glasses precursors of said glass-ceramics, and also a method of preparing said articles. Said glass-ceramics have a composition, free of arsenic oxide and antimony oxide, except for inevitable traces, expressed as percentages by weight of oxides, containing: 62% to 68% of SiO.sub.2; 17% to 21% of AI.sub.2O.sub.3; 1% to <2% of Li.sub.2O; 1% to 4% of MgO; 1% to 6% of ZnO; 0 to 4% of BaO; 0 to 4% of SrO; 0 to 1% of CaO; 1% to 5% of TiO.sub.2; 0 to 2% of ZrO.sub.2; 0 to 1% of Na.sub.2O; 0 to 1% of K.sub.2O; with Na.sub.2O+K.sub.2O+BaO+SrO+CaO<6%; optionally up to 2% of at least one fining agent comprising SnO.sub.2; and optionally up to 2% of at least one coloring agent.

Embodiments of a transparent glass-based material comprising a glass phase and a second phase that is different from and is dispersed in the glass phase are provided. The second phase may comprise a crystalline or a nanocrystalline phase, a fiber, and/or glass particles. In some embodiments, the second phase is crystalline. In one or more embodiments, the glass-based material has a transmittance of at least about 88% over a visible spectrum ranging from about 400 nm to about 700 nm and a fracture toughness of at least about 0.9 MPa.Math.m.sup.1/2, and wherein a surface of the glass-based material, when scratched with a Knoop diamond at a load of at least 5 N to form a scratch having a width w, is free of chips having a size of greater than 3w.

The present invention relates to a glass-ceramic material. The present invention also relates to a method of forming a glass-ceramic material. The present invention also relates to uses of a glass-ceramic material.

A composition includes 30 mol % to 60 mol % SiO.sub.2; 15 mol % to 40 mol % Al.sub.2O.sub.3; 5 mol % to 25 mol % Y.sub.2O.sub.3; 5 mol % to 15 mol % TiO.sub.2; and 0.1 mol % to 15 mol % RO, such that RO is a sum of MgO, CaO, SrO, and BaO.

A glass-ceramic includes SiO.sub.2 in a range of 40 mol. % to 80 mol. %; Al.sub.2O.sub.3 in a range of 5 mol. % to 20 mol. %; MgO in a range of 5 mol. % to 20 mol. %; and at least one of B.sub.2O.sub.3, ZnO, and TiO.sub.2, each in a range of 0 mol. % to 10 mol. %, such that the glass-ceramic further comprises a magnesium aluminosilicate crystalline phase at a concentration in a range of 5 wt. % to 80 wt. % of the glass-ceramic.