Abstract: The present disclosure relates to glass articles for use as a touchscreen substrate for use in a portable electronic device, particularly comprising an alkali-free aluminosilicate glass exhibiting a high damage threshold of at least 1000 gf, as measured by the lack of the presence of median/radial cracks when a load is applied to the glass using a Vickers indenter, a scratch resistance of at least 900 gf, as measured by the lack of the presence of lateral cracks when a load is applied by a moving Knoop indenter and a linear coefficient of thermal expansion (CTE) over the temperature range 0-300° C. which satisfies the relationship: 25×10-7/° C.?CTE?40×10-7/° C.

Abstract: Ion exchangeable glass articles are disclosed. In one embodiment, a glass article formed from alkali aluminosilicate glass which may include Ga2O3, Al2O3, Na2O, SiO2, B2O3, P2O5 and various combinations thereof. The glass article may generally include about X mol % of Ga2O3 and about Z mol % of Al2O3, wherein 0?X?20, 0?Z?25 and 10?(X+Z)?25. The glass article may also include from about 5 mol % to about 35 mol % Na2O, SiO2 may be present in an amount from about 40 mol % to about 70 mol % SiO2. The glass article may further include Y mol % B2O3 where Y is from 0 to about 10. The glass article may further include (10-Y) mol % of P2O5. Glass articles formed according to the present invention may be ion-exchange strengthened. In addition, the glass articles may have a low liquid CTE which enables the glass articles to be readily formed into complex shapes.

Abstract: The present invention provides the composition of an alkali-free glass composition containing no alkali metal oxide and the preparation thereof. The alkali-free glass comprising substantially no alkali metal oxide according to the present invention comprises 60 to 70 wt % of SiO2; 1 to 3.5 wt % of B2O3; 1 to 13 wt % of Al2O3; 8.5 to 14 wt % of MgO; 1 to 3 wt % of CaO; 4 to 7 wt % of SrO; and 0.5 to 7 wt % of BaO, based on the total weight of oxides present therein.

Abstract: A glass and an enclosure, including windows, cover plates, and substrates for mobile electronic devices comprising the glass. The glass has a crack initiation threshold that is sufficient to withstand direct impact, has a retained strength following abrasion that is greater than soda lime and alkali aluminosilicate glasses, and is resistant to damage when scratched. The enclosure includes cover plates, windows, screens, and casings for mobile electronic devices and information terminal devices.

Abstract: Fusion-formable sodium-containing aluminosilicate and boroaluminosilicate glasses are described. The glasses are particularly useful for controlled release of sodium—useful in semiconductor applications, such as thin film photovoltaics where the sodium required to optimize cell efficiency is to be derived from the substrate glass.

Abstract: Borosilicate glasses, preferably for use in the pharmaceutical sector, are provided. The borosilicate glasses are outstandingly suitable for the use as pharmaceutical primary packaging, such as phials or ampoules, since the aqueous or water-containing medicaments kept in the containers do not attack the glass significantly, and so the glass releases no, or only few, ions. The borosilicate glasses have the following composition in % by weight or consist thereof: SiO2 71-77; B2O3 9-12; Al2O3 5.5-8; Na2O 6-8; K2O 0.1-0.9; Li2O 0-0.3; CaO 0-1.5; BaO 0-1; F 0-0.3; Cl- 0-0.3; and MgO + CaO + BaO + SrO 0-2.

Abstract: The present invention provides the composition of an alkali-free glass composition containing no alkali metal oxide and the preparation thereof. The alkali-free glass comprising substantially no alkali metal oxide according to the present invention comprises 68 to 75 wt % of SiO2; 1 to 3 wt % of B2O3; 4 to 13 wt % of Al2O3; 1 to 6 wt % of MgO; 1 to 11 wt % of CaO; 4 to 9 wt % of SrO; and 3 to 7 wt % of BaO, based on the total weight of oxides present therein.

Abstract: A flat panel display glass substrate includes a glass comprising, in mol %, 55-80% SiO2, 3-20% Al2O3, 3-15% B2O3, and 3-25% RO (the total amount of MgO, CaO, SrO, and BaO). The contents in mol % of SiO2, Al2O3, and B2O3 satisfy a relationship (SiO2+Al2O3)/(B2O3)=7.5-17. The strain point of the glass is 665° C. or more. The devitrification temperature of the glass is 1250° C. or less. The substrate has a heat shrinkage rate of 75 ppm or less. The rate of heat shrinkage is calculated from the amount of shrinkage of the substrate measured after a heat treatment which is performed at a rising and falling temperature rate of 10° C./min and at 550° C. for 2 hours by the rate of heat shrinkage (ppm)={the amount of shrinkage of the substrate after the heat treatment/the length of the substrate before the heat treatment}×106.

Abstract: To provide granules which are to be used as raw material for aluminosilicate glass and which are capable of reducing formation of fine powder during the production thereof, and a process for their production. Granules of a glass raw material mixture comprising at least silica sand and aluminum oxide, which are to be used for production of glass, characterized in that when the granules in such a state that the water content is at most 2 mass % are subjected to screening using a sieve having 1 mm openings, D50 representing the volume cumulative median diameter in the particle size distribution curve of particles passed through the sieve, is from 350 to 5,000 ?m, and in the particle size distribution curve of water-insoluble components in the granules, the proportion of particles exceeding 50 ?m in diameter is at most 6 vol %, and D90 representing the 90% volume cumulative particle diameter from the smaller particle size side is at most 45 ?m.

Abstract: To provide a substrate for information recording medium having various properties, in particular higher fracture toughness, required for application of the substrate for information recording medium of the next generation such as perpendicular magnetic recording system, etc. and a material with excellent workability for such purpose. A crystallized glass substrate for information recording medium, consisting of a crystallized glass which comprises one or more selected from RAl2O4 and R2TiO4 as a main crystal phase, in which R is one or more selected from Zn, Mg and Fe, and in which the main crystal phase has a crystal grain size in a range of from 0.5 nm to 20 nm, a degree of crystallinity of 15% or less, and a specific gravity of 3.00 or less.

Abstract: A flat panel display glass substrate according to the present invention includes a glass comprising, as expressed in mol %, 55-80% SiO2, 3-20% Al2O3, 3-15% B2O3, 3-25% RO (the total amount of MgO, CaO, SrO, and BaO), and substantially no As2O3 and Sb2O3. The devitrification temperature of the glass is 1250° C. or less. The glass substrate has a heat shrinkage rate of 75 ppm or less. The heat shrinkage rate is calculated from the amount of shrinkage of the glass substrate measured after a heat treatment which is performed at a temperature rising and falling rate of 10° C./min and at 550° C. for 2 hours by the heat shrinkage rate (ppm)={the amount of shrinkage of the glass substrate after the heat treatment/the length of the glass substrate before the heat treatment}×106.

Abstract: A method for manufacturing an alkali-free glass includes heating the glass raw material at a temperature of 1,400 to 1,800° C. in a melting furnace to thereby prepare a molten glass, and forming the molten glass into a sheet shape, wherein heating by combustion flame of a burner and electrical heating of the molten glass by a heating electrode arranged so as to be dipped in the molten glass in the melting furnace are used in combination in the heating in the melting furnace, and when an electrical resistivity of the molten glass at 1,400° C. is Rg (?cm) and an electrical resistivity of a refractory constituting the melting furnace at 1,400° C. is Rb (?cm), the glass raw material and the refractory are selected so as to satisfy Rb>Rg.

Abstract: Described herein are aluminoborosilicate glass compositions that are substantially alkali-free and exhibit desirable physical and chemical properties for use as substrates in flat panel display devices, such as, active matrix liquid crystal displays (AMLCDs). The glass compositions can be formed into glass sheets by, for example, the float process. When used as substrates, the glass sheets exhibit dimensional stability during processing and damage resistance during cutting.

Abstract: A constitution of cover glass, the compositions consist in terms of weight % on the oxide basis, of from 64 to 69 wt. % of SiO2; from 7 to 11.5 wt. % of Al2O3; from 1.5 to 2.5 wt. % of B2O3; from 4.5 to 7.5 wt. % of MgO; 0%<CaO?2.5%; 0%<ZnO?2%; 0%<ZrO2?0.2%; 0%<TiO2?1%; from 14.5 to 16.5 wt. % of Na2O; from 1 to 4 wt. % of K2O; and 0%<SnO2?0.4%. The constitution then can be melted to form cover glass. Thereafter, the cover glass is dipped in KNO3 solution so that sodium ions, which is smaller in volume, contained in certain depth from the surface layer of the cover glass can be substituted by potassium ions, which is larger in volume. In this manner, squeezing effect is generated on the surface layer so as to form cover glass having high strength and resistance in both abrasion and scratch.

Abstract: The embodiments described herein relate to chemically and mechanically durable glass compositions and glass articles formed from the same. According to one embodiment, the glass composition may include greater than or equal to about 68 mol. % SiO2 and less than or equal to about 80 mol. % SiO2; greater than or equal to about 3 mol. % and less than or equal to about 13 mol. % alkaline earth oxide; X mol. % Al2O3, wherein X is greater than or equal to about 4 and less than or equal to about 8; Y mol. % alkali oxide, wherein the alkali oxide comprises Na2O in an amount greater than about 8 mol %; and B2O3, wherein a ratio (B2O3 (mol. %)/(Y mol. %?X mol. %) is greater than 0 and less than 0.3. In some embodiments, the glass composition may be free of phosphorous and compounds of phosphorous.

Abstract: A constitution of environment-friendly glass for TFT-LCD is provided, which is employed in Thin Film Transistor Liquid Crystal Display, the constituents consist, expressed in terms of weight % on the oxide basis, of from 59 to 63 wt. % of SiO2; from 13 to 17 wt. % of Al2O3; from 7 to 14 wt. % of B2O3; from 0.1 to 3 wt. % of BaO; from 0.5 to 3.5 wt. % of MgO; from 7 to 11 wt. % of CaO; from 0.2 to 6 wt. % of SrO; and from 0.05 to 0.4 wt. % of SnO2. The constitution then can be melted to form environment-friendly glass for TFT-LCD with high stiffness. The environment-friendly glass for TFT-LCD is formed to allow increase in chemical resistance, so as to solve the conventional problems of insufficiency in both strength and hardness and of inclusion of environment-unfriendly constituents as As2O3 or Sb2O3.

Abstract: An alkali-free glass of the present invention comprises, as a glass composition expressed in terms of oxides by mass %, 45 to 70% of SiO2, 10 to 30% of Al2O3, 11 to 20% of B2O3, less than 0.1% of As2O3, less than 0.1% of Sb2O3, and less than 0.1% of an alkali metal oxide, and has a thermal expansion coefficient (30 to 380° C.) of 30 to 35×10?7/° C.

Abstract: The invention provides a silica-alumina-sodium oxide glass easy to melt and suitable for a low temperature ion exchange process. The glass is suitable for chemical tempering and consists of 55-60 wt % of SiO2, 0.1-2.5 wt % of B2O3, 11-16 wt % of Al2O3, 14-17 wt % of Na2O, 1-8 wt % of K2O, 0-8 wt % of ZrO2, 0-5 wt % of CaO, 0-5 wt % of MgO and 0-1 wt % of Sb2O3. By reasonably setting the composition, the difficulty in glass production decreases and the glass melting temperature is reduced obviously, which is favorable to reduce energy consumption and improve yield of products. Under the condition that tempering temperature is 380?-500? and tempering time is 4-12 h, the surface compressive stress can be 610-1100 Mpa, the depth of a stress layer can be 31-80 ?m, and the glass is reinforced and has high shock resistance. The glass of the invention has high wear resistance and can be used as a protective glass material of high-grade electronic display products such as mobile phones and PDAs.

Abstract: A glass substrate for p-Si TFT flat panel displays that is composed of a glass comprising 52-78 mass % of SiO2, 3-25 mass % of Al2O3, 3-15 mass % of B2O3, 3-25 mass % of RO, wherein RO is total amount of MgO, CaO, SrO, and BaO, 0.01-1 mass % of Fe2O3, and 0-0.3 mass % of Sb2O3, and substantially not comprising As2O3, the glass having a mass ratio (SiO2+Al2O3)/B2O3 in a range of 7-30 and a mass ratio (SiO2+Al2O3)/RO equal to or greater than 6. A method for manufacturing a glass substrate involves: a melting step of obtaining a molten glass by melting, by employing at least direct electrical heating, glass raw materials blended so as to provide the aforementioned glass composition; a forming step of forming the molten glass into a flat-plate glass; and an annealing step of annealing the flat-plate glass.

Abstract: A flat panel display glass substrate according to the present invention includes a glass comprising, as expressed in mol %, 55-80% SiO2, 3-20% Al2O3, 3-15% B2O3, 3-25% RO (the total amount of MgO, CaO, SrO, and BaO), and substantially no As2O3, and Sb2O3. The devitrification temperature of the glass is 1250° C. or less. The glass substrate has a heat shrinkage rate of 75 ppm or less. The heat shrinkage rate is calculated from the amount of shrinkage of the glass substrate measured after a heat treatment which is performed at a temperature rising and falling rate of 10° C./min and at 550° C. for 2 hours by the heat shrinkage rate (ppm)={the amount of shrinkage of the glass substrate after the heat treatment/the length of the glass substrate before the heat treatment}×106.

Abstract: The invention relates to a Nd-doped, aluminate-based or silicate-based, laser glass having a peak emission wavelength that is longer than 1059.7 nm, an emission cross section (?em) of ?1.5×10?20 cm2, and/or an emission bandwidth (??eff) of ?28 nm, while maintaining properties that render the glass suitable for commercial use, such as low glass transition temperature Tg and low nonlinear index, n2.

Abstract: Described herein are alkali-free, boroalumino silicate glasses exhibiting desirable physical and chemical properties for use as substrates in flat panel display devices, such as, active matrix liquid crystal displays (AMLCDs) and active matrix organic light emitting diode displays (AMOLEDs). In accordance with certain of its aspects, the glasses possess excellent compaction and stress relaxation properties.

Abstract: Described herein are alkali-free, boroalumino silicate glasses exhibiting desirable physical and chemical properties for use as substrates in flat panel display devices, such as, active matrix liquid crystal displays (AMLCDs). In accordance with certain of its aspects, the glasses possess good dimensional stability as a function of temperature.

Abstract: A glass substrate contains specific contents of SiO2, Al2O3, B2O3, MgO, CaO, SrO, BaO, ZrO2, Na2O, K2O and Li2O. The glass substrate has a glass transition temperature of 580 to 720° C., an average coefficient of thermal expansion at 50 to 350° C. of 65×10?7 to 85×10?7/° C., a compaction (C) of 15 ppm or less, a glass surface devitrification temperature Tc of 900 to 1,300° C., a glass internal devitrification temperature Td of 900 to 1,300° C., a temperature T4 at which a viscosity reaches 104 dPa·s of 1,100 to 1,350° C., a relationship (T4?Tc) of ?50 to 350° C. and a relationship (T4?Td) of ?50 to 350° C.

Abstract: To provide chemically tempered glass which is less likely to break even if scratched. Chemically tempered glass, which comprises, as represented by mole percentage based on the following oxides, from 56 to 72% of SiO2, from 8 to 20% of Al2O3, from 9 to 25% of Na2O, from 0 to 2% of K2O, and from 0 to 15% of MgO, and which has a surface compressive stress of at least 900 MPa and an internal tensile stress of at most 30 MPa. Glass for chemical tempering, which comprises, as represented by mole percentage based on the following oxides, from 56 to 69% of SiO2, from 8 to 16% of Al2O3, from 9 to 22% of Na2O, from 0 to 1% of K2O, from 5.5 to 14% of MgO, from 0 to 2% of ZrO2, and from 0 to 6% of B2O3.

Abstract: An ion exchangeable glass having a high degree of resistance to damage caused by abrasion, scratching, indentation, and the like. The glass comprises alumina, B2O3, and alkali metal oxides, and contains boron cations having three-fold coordination. The glass, when ion exchanged, has a Vickers crack initiation threshold of at least 10 kilogram force (kgf).

Abstract: A glass that is down-drawable and ion exchangeable. The glass has a temperature T35kp at which the viscosity is 35 kilopoise. T35kp is less than the breakdown temperature Tbreakdown of zircon.

Abstract: The present disclosure relates to glass articles for use as a touchscreen substrate or cover glass article for use in a portable electronic device, particularly an aluminoborosilicate glass being substantially free of alkalis, comprising at least 55 mol % SiO2, at least 5 mol % Al2O3 and at least one alkaline earth RO component. The alkali-free aluminoborosilicate exhibits an Al2O3+B2O3 to RO mol % ratio which exceeds 1 and an Al2O3 to RO mol % ratio which exceeds 0.65. The aluminoborosilicate glasses disclosed herein exhibits high damage resistance as evidenced by a Vickers median/radial crack initiation load which is greater than than 1000 gf, as well as a high scratch resistance of at least 900 gf, as measured by the lack of the presence of lateral cracks when a load is applied by a moving Knoop indenter.

Abstract: Provided is an alkali-free glass, comprising, as a glass composition in terms of mass %, 55 to 80% of SiO2, 10 to 25% of A12O3, 2 to 5.5% of B2O3, 3 to 8% of MgO, 3 to 10% of CaO, 0.5 to 5% of SrO, and 0.5 to 7% of BaO, having a molar ratio MgO/CaO of 0.5 to 1.5, being substantially free of alkali metal oxides, and having a Young's modulus of more than 80 GPa.

Abstract: Glasses having a low softening point and high toughness. The glasses are alkali aluminoborosilicate glasses having softening points of less than 900° C. and, in some embodiments, in a range from about 650° C. up to about 825° C., and an indenter damage threshold of at least 300 g for glasses that are not chemically strengthened. The glasses are free of alkaline earth metals, lead, arsenic, antimony, and, in some embodiments, lithium.

Abstract: An ion exchangeable glass having a high degree of resistance to damage caused by abrasion, scratching, indentation, and the like. The glass comprises alumina, B2O3, and alkali metal oxides, and contains boron cations having three-fold coordination. The glass, when ion exchanged, has a Vickers crack initiation threshold of at least 10 kilogram force (kgf).

Abstract: Alkali aluminosilicate glasses that are resistant to damage due to sharp impact and capable of fast ion exchange are provided. The glasses comprise at least 4 mol % P2O5 and, when ion exchanged, have a Vickers indentation crack initiation load of at least about 7 kgf.

Abstract: Described herein are alkali-free, boroalumino silicate glasses exhibiting desirable physical and chemical properties for use as substrates in flat panel display devices, such as, active matrix liquid crystal displays (AMLCDs). In accordance with certain of its aspects, the glasses possess good dimensional stability as a function of temperature.

Abstract: Described herein are alkali-free, boroalumino silicate glasses exhibiting desirable physical and chemical properties for use as substrates in flat panel display devices, such as, active matrix liquid crystal displays (AMLCDs) and active matrix organic light emitting diode displays (AMOLEDs). In accordance with certain of its aspects, the glasses possess excellent compaction and stress relaxation properties.

Abstract: An ion exchangeable glass that is free of lithium and comprising 0.1-10 mol % P2O5 and at least 5 mol % Al2O3. The presence of P2O5 enables the glass to be ion exchanged more quickly and to a greater depth than comparable glasses that do not contain P2O5.

Abstract: The present invention provides the composition of an alkali-free glass composition containing no alkali metal oxide and the preparation thereof. The alkali-free glass comprising substantially no alkali metal oxide according to the present invention comprises 68 to 75 wt % of SiO2; 1 to 3 wt % of B2O3; 4 to 13 wt % of Al2O3; 1 to 6 wt % of MgO; 1 to 11 wt % of CaO; 4 to 9 wt % of SrO; and 3 to 7 wt % of BaO, based on the total weight of oxides present therein.

Abstract: To provide a glass ceramic composition with which a substrate for a light emitting element having a high reflectance and a high thermal conductivity can be obtained, and which can suppress breakage at the time of production of the substrate for a light emitting element. A glass ceramic composition to be used for production of a substrate on which a light emitting element is to be mounted, which comprises from 30 to 45 mass % of a glass powder, from 35 to 50 mass % of an alumina powder and from 10 to 30 mass % of a zirconia powder, to the total amount of the glass powder, the alumina powder and the zirconia powder, wherein the average particle size of the zirconia powder is at most ¼ of the average particle size of the alumina powder.

Abstract: Described herein are alkali-free, boroalumino silicate glasses exhibiting desirable physical and chemical properties for use as substrates in flat panel display devices, such as, active matrix liquid crystal displays (AMLCDs). In accordance with certain of its aspects, the glasses possess good dimensional stability as a function of temperature.

Abstract: Sodium containing aluminosilicate and boroaluminosilicate glasses are described herein. The glasses can be used as substrates or superstrates for photovoltaic devices, for example, thin film photovoltaic devices such as CIGS photovoltaic devices. These glasses can be characterized as having strain points ?535° C., for example, ?570° C., thermal expansion coefficients of from 8 to 9 ppm/° C., as well as liquidus viscosities in excess of 50,000 poise. As such they are ideally suited for being formed into sheet by the fusion process.

Abstract: A glass substrate for a display, which is formed of a glass having a light weight and having high refinability with decreasing environmental burdens, the glass comprising, by mass %, 50 to 70% of SiO2, 5 to 18% of B2O3, 10 to 25% of Al2O3, 0 to 10% of MgO, 0 to 20% of CaO, 0 to 20% of SrO, 0 to 10% of BaO, 5 to 20% of RO (in which R is at least one member selected from the group consisting of Mg, Ca, Sr and Ba), and over 0.20% but not more than 2.0% of R?2O (in which R? is at least one member selected from the group consisting of Li, Na and K), and containing, by mass %, 0.05 to 1.5% of oxide of metal that changes in valence number in a molten glass, and substantially containing none of As2O3, Sb2O3 and PbO.

Abstract: It is an object of the present invention to provide a crystallized glass which has various properties required for employing the substrate for information recording medium of the next generation, and also has significantly low specific gravity; and a crystallized glass substrate for information recording medium. A crystallized glass containing, as a crystal phase, one or more selected from RAl2O4 and R2TiO4 (wherein R is one or more selected from Mg and Fe), the crystallized glass comprising the components of SiO2 of 50% to 70%, Al2O3 of 10% to 26%, TiO2 of 1 to 15%, MgO of 2.5% to 25%, FeO of 0% to 8%, and ZnO of 0% to less than 2%, expressed in terms of mass percentage on an oxide basis, wherein the value of (Al2O3+MgO)/SiO2 is 0.30 or more and 0.65 or less, and a specific gravity is less than 2.63.

Abstract: The present disclosure relates to a glass composition having a low thermal expansion coefficient, specifically, a glass composition comprising about 55 to less than 64 weight percent of silicon oxide, about 15 to about 30 weight percent of aluminum oxide, about 5 to about 15 weight percent of magnesium oxide, about 3 to about 10 weight percent boron oxide, about 0 to about 11 weight percent calcium oxide, and about 0 to about 2 weight percent of alkali oxide, the remainder being trace compounds of less than about 1 weight percent, is provided. Glass fibers and composite articles formed therefrom are also provided.

Abstract: An abrasive article including an abrasive body having abrasive grains made of microcrystalline alumina contained within a bond material, wherein the bond material comprises a total content of alumina of at least about 15 mol %.

Abstract: A glass substrate for information recording medium, said glass substrate being composed of an alminosilicate glass containing 60-75% by mass of SiO2, 5-18% by mass of Al2O3, 3-10% by mass of Li2O, 3-15% by mass of Na2O and 0.5-8% by mass of ZrO2 relative to the entire glass components. The glass substrate for information recording medium contains neither As (arsenic) nor Sb (antimony), while containing at least one polyvalent element selected from the group consisting of V (vanadium), Mn (manganese), Ni (nickel), Nb (niobium), Mo (molybdenum), Sn (tin), Ce (cerium), Ta (tantalum) and Bi (bismuth). The molar ratio of the total amount of the polyvalent elements to the amount of ZrO2 is within the range of 0.05-0.50.

Abstract: An ion exchangeable glass having a high degree of resistance to damage caused by abrasion, scratching, indentation, and the like. The glass comprises alumina, B2O3, and alkali metal oxides, and contains boron cations having three-fold coordination. The glass, when ion exchanged, has a Vickers crack initiation threshold of at least about 30 kilogram force.

Abstract: Glass compositions are provided that are useful in electronic applications, e.g., as reinforcements in printed circuit board substrates. Reduced dielectric constants are provided relative to E-glass, and fiber forming properties are provided that are more commercially practical than D-glass.

Abstract: Glass compositions are provided that are useful in a variety of applications including, for example, electronics applications, reinforcement applications, and others. Some embodiments of glass compositions can provide desirable dielectric constants, desirable dissipation factors, and/or desirable mechanical properties while also having desirable fiber forming properties.

Abstract: Disclosed are a glass substrate for an information recording medium, having excellent scratch resistance and a light weight and having high fracture toughness, the glass substrate having a fragility index value, measured in water, of 12 ?m?1/2 or less or having a fragility index value, measured in an atmosphere having a dew point of ?5° C. or lower, of 7 ?m?1/2 or less, or the glass substrate comprising, by mol %, 40 to 75% of SiO2, 2 to 45% of B2O3 and/or Al2O3 and 0 to 40% of R?2O in which R? is at least one member selected from the group consisting of Li, Na and K), wherein the total content of SiO2, B2O3, Al2O3 and R?2O is at least 90 mol %, and a magnetic information recording medium comprising a magnetic recording layer formed on the glass substrate.

Abstract: There is provided a glass for chemical strengthening having a black color tone and excelling in characteristics preferred for the purposes of housing or decoration of an electronic device, that is, bubble quality, strength, and light transmittance characteristics. A glass for chemical strengthening contains, in mole percentage based on following oxides, 55% to 80% of SiO2, 3% to 16% of Al2O3, 0% to 12% of B2O3, 5% to 16% of Na2O, 0% to 4% of K2O, 0% to 15% of MgO, 0% to 3% of CaO, 0% to 18% of ?RO (where R represents Mg, Ca, Sr, Ba or Zn), 0% to 1% of ZrO2, and 0.1% to 7% of a coloring component having at least one metal oxide selected from the group consisting of oxides of Co, Mn, Fe, Ni, Cu, Cr, V and Bi.

Abstract: An alkali aluminosilicate glass that is chemically strengthened and has a down-drawable composition. The glass has a melting temperature less than about 1650° C. and a liquidus viscosity of at least 130 kpoise and, in one embodiment, greater than 250 kpoise. The glass undergoes ion exchange at relatively low temperatures to a depth of at least 30 ?m.