The present invention provides an alkali-free glass sheet, including as a glass composition, in terms of mol%, 64% to 71% of SiO.sub.2, 12.5% to 17% of Al.sub.2O.sub.3, 0% to 4% of B.sub.2O.sub.3, 0% to 0.5% of Li.sub.2O+Na.sub.2O+K.sub.2O, 6% to 11% of MgO, 3% to 11% of CaO, 0% to 6% of SrO, 0% to 1% of BaO, and 14% to 19% of MgO+CaO+SrO+BaO, and having a mole percent ratio (Al.sub.2O.sub.3/CaO)×{B.sub.2O.sub.3/(MgO+CaO+SrO+BaO)} of from 0 to 0.5, a mole percent ratio MgO/(CaO+SrO) of from 0.5 to 1.5, a mole percent ratio (MgO+CaO+SrO+BaO-Al.sub.2O.sub.3)×B.sub.2O.sub.3 of from 1 to 10, and a mole percent ratio SiO.sub.2×CaO/MgO of from 30 to 90.

The present invention provides an alkali-free glass sheet, including as a glass composition, in terms of mol%, 64% to 71% of SiO.sub.2, 12.5% to 17% of Al.sub.2O.sub.3, 0% to 4% of B.sub.2O.sub.3, 0% to 0.5% of Li.sub.2O+Na.sub.2O+K.sub.2O, 6% to 11% of MgO, 3% to 11% of CaO, 0% to 6% of SrO, 0% to 1% of BaO, and 14% to 19% of MgO+CaO+SrO+BaO, and having a mole percent ratio (Al.sub.2O.sub.3/CaO)×{B.sub.2O.sub.3/(MgO+CaO+SrO+BaO)} of from 0 to 0.5, a mole percent ratio MgO/(CaO+SrO) of from 0.5 to 1.5, a mole percent ratio (MgO+CaO+SrO+BaO-Al.sub.2O.sub.3)×B.sub.2O.sub.3 of from 1 to 10, and a mole percent ratio SiO.sub.2×CaO/MgO of from 30 to 90.

The present invention relates to a crystallized glass including: at least one crystal of indialite and cordierite, in which the crystallized glass has a total amount of the crystal is 40 mass % or more of the crystallized glass, and the crystal comprises at least one of a vacancy and a different element at an Al site.

The present invention relates to a glass ceramic for veneering a dental frame structure, wherein said glass ceramic is characterized by a high content of B.sub.2O.sub.3, to a process for the preparation thereof, and to the use thereof in the production of dental restorations.

Scratch and damage resistant laminated glass articles are disclosed. According to one aspect, a laminated glass article may include a glass core layer formed from core glass composition and includes a core glass elastic modulus E.sub.C and at least one glass clad layer fused directly to the glass core layer. The at least one glass clad layer may be formed from an ion exchangeable clad glass composition different than the core glass composition and includes a clad glass elastic modulus E.sub.CL. The laminated glass article may have a total thickness T and the at least one glass clad layer may have a thickness T.sub.CL that is greater than or equal to 30% of the total thickness T. E.sub.C may be at least 5% greater than E.sub.CL.

Embodiments of a glass-based article including a first surface and a second surface opposing the first surface defining a thickness (t) of about 3 millimeters or less (e.g., about 1 millimeter or less), and a stress profile, wherein all points of the stress profile between a thickness range from about 0.Math.t up to 0.3.Math.t and from greater than about 0.7.Math.t up to t, comprise a tangent with a slope having an absolute value greater than about 0.1 MPa/micrometer, are disclosed. In some embodiments, the glass-based article includes a non-zero metal oxide concentration that varies along at least a portion of the thickness (e.g., 0.Math.t to about 0.3.Math.t) and a maximum central tension in the range from about 80 MPa to about 100 MPa. In some embodiments, the concentration of metal oxide or alkali metal oxide decreases from the first surface to a value at a point between the first surface and the second surface and increases from the value to the second surface. The concentration of the metal oxide may be about 0.05 mol % or greater or about 0.5 mol % or greater throughout the thickness. Methods for forming such glass-based articles are also disclosed.

Embodiments of a glass-based article including a first surface and a second surface opposing the first surface defining a thickness (t) of about 3 millimeters or less (e.g., about 1 millimeter or less), and a stress profile, wherein all points of the stress profile between a thickness range from about 0.Math.t up to 0.3.Math.t and from greater than about 0.7.Math.t up to t, comprise a tangent with a slope having an absolute value greater than about 0.1 MPa/micrometer, are disclosed. In some embodiments, the glass-based article includes a non-zero metal oxide concentration that varies along at least a portion of the thickness (e.g., 0.Math.t to about 0.3.Math.t) and a maximum central tension in the range from about 80 MPa to about 100 MPa. In some embodiments, the concentration of metal oxide or alkali metal oxide decreases from the first surface to a value at a point between the first surface and the second surface and increases from the value to the second surface. The concentration of the metal oxide may be about 0.05 mol % or greater or about 0.5 mol % or greater throughout the thickness. Methods for forming such glass-based articles are also disclosed.

Provided is a glass direct roving that can achieve good productivity for long glass fiber-reinforced thermoplastic resin pellets, and achieve excellent spinning productivity and good strength of glass fiber-reinforced resin molded articles produced by using long glass fiber-reinforced thermoplastic resin pellets in combination. The glass direct roving includes a plurality of glass filaments bundled together, wherein the filament diameter of the glass filaments, D, is in the range of 17.5 to 21.5 μm, the number of the glass filaments bundled, F, is in the range of 3000 to 7000, the mass of the glass direct roving is in the range of 2450 to 4000 tex, the ignition loss of the glass direct roving, L, is in the range of 0.03 to 0.90%, and the D, F, and L satisfy the following formula (1): $\begin{array}{cc}1050\le \left(D^4\times F^{1/4}\right)/\left(1000\times L^{1/6}\right)\le 1640.& \left(1\right)\end{array}$

A formed or non-flat formed glass is provided that exhibits high transmittance to electromagnetic radiation in a range of wavelengths from 200 nm to 1500 nm. The transmittance for the formed or non-flat formed glass having a thickness of 1 mm is 20% or more at a wavelength of 254 nm, 82% or more at a wavelength of 300 nm, 90% or more at a wavelength of 350 nm, 92% or more at a wavelength of 546 nm, 92.5% or more at a wavelength of 1400 nm, 91.5% or more in a wavelength range from 380 nm to 780 nm, and 92.5% or more in a wavelength range from 780 nm to 1500 nm.

A formed or non-flat formed glass is provided that exhibits high transmittance to electromagnetic radiation in a range of wavelengths from 200 nm to 1500 nm. The transmittance for the formed or non-flat formed glass having a thickness of 1 mm is 20% or more at a wavelength of 254 nm, 82% or more at a wavelength of 300 nm, 90% or more at a wavelength of 350 nm, 92% or more at a wavelength of 546 nm, 92.5% or more at a wavelength of 1400 nm, 91.5% or more in a wavelength range from 380 nm to 780 nm, and 92.5% or more in a wavelength range from 780 nm to 1500 nm.