The present invention relates to a chemically strengthened glass, satisfying: a ratio ICS (≥400)/ICS being more than 0.13 in a stress profile, the ICS representing an integrated value of compressive stress in a region from a surface of the glass to a depth where the compressive stress becomes 0 in the stress profile, and the ICS (≥400) representing an integrated value of compressive stress in a region from a depth of 400 μm from the surface of the glass to the depth where the compressive stress becomes 0 in the stress profile.

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.

The present invention discloses a microcrystalline glass, a microcrystalline glass product, and a manufacturing method therefor. The main crystal phase of the microcrystalline glass comprises lithium silicate and a quartz crystal phase. The haze of the microcrystalline glass of the thickness of 0.55 mm is below 0.6%. The microcrystalline glass comprises the following components in percentage by weight: SiO.sub.2: 65-85%; Al.sub.2O.sub.3: 1-15%; Li.sub.2O: 5-15%; ZrO.sub.2: 0.1-10%; P.sub.2O.sub.5: 0.1-10%; K.sub.2O: 0-10%; MgO: 0-10%; ZnO: 0-10%. A four-point bending strength of the microcrystalline glass product is more than 600 Mpa.

The purpose of the present invention is to provide a chemically strengthened glass having excellent transparency and strength and being scratch resistant. The present invention pertains to a chemically strengthened glass that: has a compressive stress layer on the surface thereof; has a visible light transmittance of at least 70% when the thickness thereof is converted to 0.8 mm; has a surface compressive stress of at least 600 MPa; has a compressive stress depth of at least 80 μm; and contains a β-spodumene.

Disclosed is a machinable dental bulk block that is a glass ceramic block including an amorphous glass matrix and crystalline phases introduced into the matrix. A major crystalline phase is lithium disilicate and minor crystalline phases are lithium phosphate and at least one of spodumene and virgilite. The dental block is made of a functionally gradient material in which the major crystalline phase exhibits a gradient of particle sizes in a depth direction of the dental block and which has no interface at a point where the gradient of particle sizes of the major crystalline phase changes. The dental bulk block is useful for production of a dental prosthesis (artificial tooth) similar to a natural tooth. The dental bulk block can reduce time and the number of processing steps to manufacture a dental prosthesis and provides improved structural stability through good force distribution obtained by functionally graded mechanical properties.

To provide an inorganic composition article containing at least one kind selected from α-cristobalite and α-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.

Lithium silicate-low quartz glass ceramics are described which are characterized by a combination of very good mechanical and optical properties and can therefore be used in particular as restoration material in dentistry.

A transparent colored glass ceramic, in particular an LAS glass ceramic, suitable for use as a cooking surface is provided. The transparent colored glass ceramic includes high-quartz solid solution (HQ s.s.) as a main crystal phase and exhibits thermal expansion of −1 to +1 ppm/Kin the range from 20° C. to 700° C. The glass ceramic has from 3.0 to 3.6 percent by weight of lithium oxide (Li.sub.2O) as constituents and either is colored with 0.003 to 0.05 percent by weight of vanadium oxide (V.sub.2O.sub.5) or is colored with 0.003 to 0.25 percent by weight of molybdenum oxide (MoO.sub.3).

A glass composition includes: greater than or equal to 53 mol % and less than or equal to 70 mol % SiO.sub.2; greater than or equal to 9 mol % and less than or equal to 20 mol % Al.sub.2O.sub.3; greater than or equal to 10 mol % and less than or equal to 17.5 mol % B.sub.2O.sub.3; greater than or equal to 0 mol % Li.sub.2O; greater than or equal to 0 mol % Na.sub.2O; and greater than 0.1 mol % of a nucleating agent. The sum of Li.sub.2O and Na.sub.2O in the glass composition may be greater than or equal to 8 mol % and less than or equal to 30 mol %. The amount of Al.sub.2O.sub.3 minus the sum of R.sub.2O and RO in the glass composition may be greater than or equal to −3 mol %. The glass composition may be phase separable and may have an improved K.sub.Ic fracture toughness.

A glass-ceramic article comprises: a center-volume composition comprising (on an oxide basis): 55-75 mol % SiO.sub.2; 0.2-10 mol % Al.sub.2O.sub.3; 0-5 mol % B.sub.2O.sub.3; 15-30 mol % Li.sub.2O; 0-2 mol % Na.sub.2O; 0-2 mol % K.sub.2O; 0-5 mol % MgO; 0-2 mol % ZnO; 0.2-3.0 mol % P.sub.2O.sub.5; 0.1-10 mol % ZrO.sub.2; 0-4 mol % TiO.sub.2; and 0-1.0 mol % SnO.sub.2. Lithium disilicate and either β-spodumene or β-quartz are the two predominant crystalline phases (by weight) of the glass-ceramic article. The glass-ceramic article further comprises tetragonal ZrO.sub.2 as a crystalline phase. The composition of the glass-ceramic article from a primary surface into a thickness of the glass-ceramic article can comprise over 10 mol % Na.sub.2O (on an oxide basis), with the mole percentage of Na.sub.2O decreasing from the primary surface towards the center-volume. The glass-ceramic article exhibits a ring-on-ring load-to-failure of at least 120 kgf, when the thickness of the glass-ceramic article is 0.3 mm to 2.0 mm.