Abstract: To provide glass to be used for chemically tempered glass which is hardly broken even when flawed. Glass for chemical tempering, which comprises, as represented by mole percentage based on the following oxides, from 65 to 85% of SiO2, from 3 to 15% of Al2O3, from 5 to 15% of Na2O, from 0 and less than 2% of K2O, from 0 to 15% of MgO and from 0 to 1% of ZrO2, and has a total content SiO2+Al2O3 of SiO2 and Al2O3 of at most 88%.

Abstract: A glass composition for substrates having good polishability while securing characteristics for FPD substrates, especially for PDP substrates, from which a glass substrate having excellent polishing workability and productivity can be obtained, is provided. A glass composition for substrates, which is characterized by comprising, as represented by mass % based on oxides, from 55 to 75% of SiO2, from 5 to 15% of Al2O3, from 0 to 4% of MgO, more than 5.5% and at most 12% of CaO, from 5 to 18% of SrO, from 0 to 13% of BaO, from 0.5 to 6% of ZrO2, from 0 to 10% of Na2O, from 0 to 15% of K2O, from 6 to 20% of Na2O+K2O, from 17 to 25% of MgO+CaO+SrO+BaO, and from 15 to 25% of CaO+SrO, as a glass matrix composition; and having a glass transition point of at least 600° C., an average thermal expansion coefficient of from 75×10?7 to 90×10?7/° C. within a range of from 50 to 350° C., and an abrasion resistance of at least 98.

Abstract: To provide a process to improve acid resistance of a glass substrate for an information recording medium. A process for producing the glass substrate for an information recording medium, includes processing a glass formed into a plate by a float process, a down-draw method or a press method, wherein, in cooling the glass at the last step the glass has a temperature of at least its strain point, the time during which the glass temperature is at least its strain point and at most a temperature where the glass viscosity is 1010dPa·s is at least 13 minutes.

Abstract: The present invention relates to a method for manufacturing a glass substrate for information recording medium, the method including: a lapping step of lapping a circular glass plate made of an alkali aluminosilicate glass; and a subsequent cerium oxide polishing step of polishing the circular glass plate with a slurry containing a cerium oxide abrasive, in which a difference (SiO2?Al2O3) obtained by subtracting an Al2O3 content from an SiO2 content in the alkali aluminosilicate glass is 62% by mole or less; and in which the method further includes: subsequently to the cerium oxide polishing step, a cleaning step of cleaning the circular glass plate with a cleaning liquid having a sulfuric acid concentration of 20% by mass or more and 80% by mass or less and a hydrogen peroxide concentration of 1% by mass or more and 10% by mass or less at a liquid temperature of 50° C. or higher and 100° C.

Abstract: To provide a method for producing chemically tempered glass, whereby the chemical tempering can be done at a low temperature and in a short time. A method for producing chemically tempered glass, which comprises chemically tempering glass for chemical tempering, comprising, as represented by mole percentage based on the following oxides, from 60 to 75% of SiO2, from 5 to 15% of Al2O3, from 1 to 12% of MgO, from 0 to 3% of CaO, from 0 to 3% of ZrO2, from 10 to 20% of Li2O, from 0 to 8% of Na2O and from 0 to 5% of K2O, and having a total content R2O of Li2O, Na2O and K2O of at most 25%, and a ratio Li2O/R2O of the Li2O content to R2O of from 0.5 to 1.0.

Abstract: A process for producing a glass substrate for information recording media, comprising lapping a glass disk made of low alkali aluminosilicate glass that contains no alkali metal oxide or contains alkali metal oxides in a total amount of less than 4 mol %, and subsequently polishing the glass disk by using a slurry that contains cerium oxide abrasives, characterized by cleaning the glass disk by using a cleaning liquid that contains sulfuric acid at a concentration of from 20 mass % to 80 mass % and hydrogen peroxide at a concentration of from 0.5 mass % to 10 mass % at a liquid temperature of from 50° C. to 100° C., and thereafter polishing the main surface of the glass disk, by using a slurry that contains colloidal silica abrasives.

Abstract: To provide a method for producing a magnetic disk, whereby a magnetic recording layer is formed at a high temperature. A method for producing a magnetic disk, which comprises a step of forming a magnetic recording layer on a glass substrate having a temperature of at least 550° C., wherein the glass substrate comprises, as represented by mol percentage, from 62 to 74% of SiO2, from 6 to 18% of Al2O3, from 2 to 15% of B2O3 and from 8 to 21%, in total, of at least one component selected from MgO, CaO, SrO and BaO, provided that the total content of the above seven components is at least 95%, and further contains less than 1%, in total, of at least one component selected from Li2O, Na2O and K2O, or contains none of these three components.

Abstract: A glass for an information recording medium substrate, which comprises, as represented by mol % based on the following oxides, from 61 to 72% of SiO2, from 3 to 11% of Al2O3, from 0 to 14.3% of Li2O, from 0 to 22% of Na2O, from 0 to 22% of K2O, from 4 to 13% of MgO, from 0 to 6% of TiO2 and from 0 to 5% of ZrO2, provided that the total content of Li2O, Na2O and K2O (R2O) is from 10 to 22%, and (a) the ratio of the content of Li2O to R2O (Li2O/R2O) is at most 0.52, (b) the ratio of the content of Na2O to R2O (Na2O/R2O) is at least 0.35, or (c) the ratio of the content of K2O to R2O (K2O/R2O) is at least 0.45.

Abstract: To provide glass to be used for a substrate which is, as a substrate, less susceptible to surface roughening even if subjected to cleaning by means of a strongly acidic solution. Glass for a substrate, which comprises, as represented by mol % based on the following oxides, from 62.5 to 69% of SiO2, from 9 to 15.5% of Al2O3, from 8 to 16 of Li2O, from 0 to 8% of Na2O, from 0 to 7% of K2O and from 0 to 3.5% of ZrO2, provided that SiO2—Al2O3 is at least 53.3%, Li2O+Na2O+K2O is from 17 to 24%, and the total of contents of the above six components is at least 97%.

Abstract: To provide a glass for an information recording media substrate, which is excellent in weather resistance. A glass for an information recording media substrate, which comprises, as represented by mol % based on oxide, from 61 to 66% of SiO2, from 11.5 to 17% of Al2O3, from 8 to 16% of Li2O, from 2 to 8% of Na2O, from 2.5 to 8% of K2O, from 0 to 6% of MgO, from 0 to 4% of TiO2 and from 0 to 3% of ZrO2, provided that Al2O3+MgO+TiO2 is at least 12%, and Li2O+Na2O+K2O is from 16 to 23%, wherein in a case of where B2O3 is contained, its content is less than 1%. The above glass for an information recording media substrate, wherein when the glass is left under steam atmosphere at 120° C. at 0.2 MPa for 20 hours, and the amount of Li, the amount of Na and the amount of K, which precipitate on a surface of the glass are represented as CLi, CNa and CK respectively, CNa is at most 0.7 nmol/cm2, and CLi+CNa+CK is at most 3.5 nmol/cm2.

Abstract: Glass for a display device, which comprises, as represented by mole percentage based on the following oxides, from 61 to 72% of SiO2, from 8 to 17% of Al2O3, from 6 to 18% of Li2O, from 2 to 15% of Na2O, from 0 to 8% of K2O, from 0 to 6% of MgO, from 0 to 6% of CaO, from 0 to 4% of TiO2, and from 0 to 2.5% of ZrO2, and having a total content R2O of Li2O, Na2O and K2 O of from 15 to 25%, a ratio Li2O/R2O of the Li2O content to R2O of from 0.35 to 0.8, and a total content of MgO and CaO of from 0 to 9%.

Abstract: The present invention provides a glass substrate for flat panel display in which yellowing occurring in a case of forming silver electrodes on glass substrate surface is inhibited. A glass substrate for flat panel display, which is formed by a float method, which has a composition consisting essentially of, in terms of oxide amount in mass %: SiO2 50 to 72%, Al2O3 0.15 to 15%, MgO + CaO + SrO + BaO 4 to 30%, Na2O more than 0% and at most 10%, K2O 1 to 21%, Li2O 0 to 1%, Na2O + K2O + Li2O 6 to 25%, ZrO2 0 to 10%, and Fe2O3 0.0725 to 0.15%; and wherein the average Fe2+ content in a surface layer of the glass substrate within a depth of 10 ?m from the a top surface is at most 0.0725% in terms of Fe2O3 amount.

Abstract: A glass substrate for an information recording medium, comprising an alkali aluminosilicate glass, wherein the ?—OH value is at least 0.20 mm?1.

Abstract: To provide glass for a data storage medium substrate, whereby high heat resistance can be obtained. Glass for a data storage medium substrate, which comprises, as represented by mol percentage based on the following oxides, from 55 to 70% of SiO2, from 2.5 to 9% of Al2O3, from 0 to 10% of MgO, from 0 to 7% of CaO, from 0.5 to 10% of SrO, from 0 to 12.5% of BaO, from 0 to 2.5% of TiO2, from 0.5 to 3.7% of ZrO2, from 0 to 2.5% of Li2O, from 0 to 8% of Na2O, from 2 to 8% of K2O and from 0.5 to 5% of La2O3, provided that the total content of Al2O3 and ZrO2 (Al2O3+ZrO2) is at most 12%, and the total content of Li2O, Na2O and K2O (R2O) is at most 12%.

Abstract: The present invention relates to a method for manufacturing a glass substrate for data storage mediums, the method including a chemical strengthening treatment step of dipping a glass for a substrate including, in terms of mol % on the basis of oxides, from 58 to 66% of SiO2, from 9 to 15% of Al2O3, from 7 to 15% of Li2O and from 2 to 9% of Na2O, provided that Li2O+Na2O is from 13 to 21%, in a mixed molten salt to form a compressive layer on front and back surfaces of the glass for a substrate, in which the mixed molten salt includes, in terms of mass percent, from 1 to 7.5% of lithium nitrate, from 28 to 55% of sodium nitrate and from 40 to 69% of potassium nitrate.

Abstract: To provide a process to improve acid resistance of a glass substrate for an information recording medium. A process for producing a glass substrate for an information recording medium, comprising processing a glass formed into a plate by a float process, a down-draw method or a press method, wherein, in cooling of the glass in the last step where the glass has a temperature of at least its strain point, the time during which the glass temperature is at least its strain point and at most a temperature where the glass viscosity is 1010 dPa·s is at least 13 minutes.

Abstract: To provide a glass for an information recording medium substrate, which is excellent in weather resistance. A glass substrate for an information recording medium, which is made of an alkali aluminosilicate glass, wherein the difference obtained by subtracting the glass transition temperature Tg from the fictive temperature Tf, i.e. Tf?Tg, is at most 5° C. The glass substrate for an information recording medium, which comprises, as represented by mol % based on the following oxides, from 64 to 67% of SiO2, from 8 to 10% of Al2O3, from 10 to 13% of Li2O, from 9 to 12% of Na2O, from 0 to 2% of K2O and from 2 to 4% of ZrO2, provided that the total content of Li2O, Na2O and K2O, i.e. Li2O+Na2O+K2O, is from 21 to 25%.

Abstract: A float glass for a display substrate, characterized in that its composition consists essentially of, as represented by mass % based on oxide, from 52 to 62% of SiO2, from 5 to 15% of Al2O3, from more than 0% to 9% of MgO, from 3 to 12% of CaO, from 9 to 18% of SrO, from 0 to 13% of BaO, from 25 to 30% of MgO+CaO+SrO+BaO, from 6 to 14% of Na2O+K2O+Li2O, from 0 to 6% of ZrO2 and from 0 to 1% of SO3, the temperature of glass melt corresponding to the viscosity of 102 dPa·s is at most 1,520° C., the temperature of glass melt corresponding to the viscosity of 104 dPa·s is at most 1,120° C., the glass transition temperature is at least 610° C., and the specific gravity is at most 2.9.

Abstract: The present invention relates to a method for manufacturing a glass substrate for information recording medium, the method including: a lapping step of lapping a circular glass plate made of an alkali aluminosilicate glass; and a subsequent cerium oxide polishing step of polishing the circular glass plate with a slurry containing a cerium oxide abrasive, in which a difference (SiO2?Al2O3) obtained by subtracting an Al2O3 content from an SiO2 content in the alkali aluminosilicate glass is 62% by mole or less; and in which the method further includes: subsequently to the cerium oxide polishing step, a cleaning step of cleaning the circular glass plate with a cleaning liquid having a sulfuric acid concentration of 20% by mass or more and 80% by mass or less and a hydrogen peroxide concentration of 1% by mass or more and 10% by mass or less at a liquid temperature of 50° C. or higher and 100° C.

Abstract: To provide a glass for an information recording media substrate, which is excellent in weather resistance. A glass for an information recording media substrate, which comprises, as represented by mol % based on oxide, from 61 to 66% of SiO2, from 11.5 to 17% of Al2O3, from 8 to 16% of Li2O, from 2 to 8% of Na2O, from 2.5 to 8% of K2O, from 0 to 6% of MgO, from 0 to 4% of TiO2 and from 0 to 3% of ZrO2, provided that Al2O3+MgO+TiO2 is at least 12%, and Li2O+Na2O+K2O is from 16 to 23%, wherein in a case of where B2O3 is contained, its content is less than 1%. The above glass for an information recording media substrate, wherein when the glass is left under steam atmosphere at 120° C. at 0.2 MPa for 20 hours, and the amount of Li, the amount of Na and the amount of K, which precipitate on a surface of the glass are represented as CLi, CNa and CK respectively, CNa is at most 0.7 nmol/cm2, and CLi+CNa+CK is at most 3.5 nmol/cm2.