Abstract: A glass, which is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording and reproducing apparatus, is an amorphous oxide glass. An SiO2 content ranges from 56 mol % to 80 mol %, an Li2O content ranges from 1 mol % to 10 mol %, a B2O3 content ranges from 0 mol % to 4 mol %, a Na2O content is 0 mol %, a total content of MgO and CaO (MgO+CaO) ranges from 9 mol % to 40 mol %, and the oxide glass has a specific gravity of 2.75 g/cm3 or less, a glass transition temperature of 650° C. or higher, and a Young's modulus of 90 GPa or more.

Abstract: A glass member for a housing of an electronic device may include an aluminosilicate glass substrate defining a first surface of the glass member, the first surface having a first surface roughness, a fused composite coating bonded to a portion of the aluminosilicate glass substrate and defining a second surface of the glass member, the second surface having a second surface roughness greater than the first surface roughness, a first ion-exchanged layer extending into the glass member and through the fused composite coating, and a second ion-exchanged layer extending into the glass member from the first surface. The fused composite coating may include an amorphous glass matrix and a crystalline material dispersed in the amorphous glass matrix.

Abstract: Letting a particle diameter be Dx (?m) when a cumulative particle volume cumulated from the small particle diameter side reaches x (%) of the total particle volume in a particle size distribution obtained regarding cerium oxide included in a polishing liquid using a laser diffraction/scattering method, D5 is 1 ?m or less, and a difference between D95 and D5 is 3 ?m or more.

Abstract: Techniques for determining a maximum permissible media deposition temperature for depositing one or more layers over a substrate of a heat assisted magnetic recording (HAMR) platform. In one aspect, a method includes controlling a thermomechanical analyzer to measure the mechanical expansion of a glass material versus temperature within a temperature range that is below the primary transformation temperature (Tg) of the glass material to detect a possible initial transformation that occurs within the glass material at a temperature (Tt) below the primary transformation temperature (Tg). If such an initial transformation is detected, the maximum deposition temperature is set based on the initial transformation temperature (Tt), rather than on the primary transformation temperature (Tg). Otherwise, the maximum permissible media deposition temperature is set based on the transformation temperature (Tg).

Abstract: A glass substrate and a method for manufacturing the glass substrate are provided. The glass substrate may include a base glass including SiO2, Al2O3, and Li2O, and nanocrystals having an average diameter in a range from about 5 nm to about 10 nm, thereby exhibiting enhanced surface strength properties while maintaining good transmittance properties. The method may include a step of heat-treating a base glass, thereby providing a glass substrate having enhanced strength properties.

Abstract: A crystallized glass includes a crystallized glass mother material, and, in a surface, a compressive stress layer, wherein the crystallized glass has, for a thickness of 10 mm, a light transmittance of, including reflection loss, 80% at a wavelength in 400 to 669 nm, and has a Vickers hardness [Hv] of 835 to 1300. In the crystallized glass, the crystallized glass mother material contains, in % by weight on an oxide basis, 40.0% to 70.0% of a SiO2 component, 11.0% to 25.0% of an Al2O3 component, 5.0% to 19.0% of a Na2O component, 0% to 9.0% of a K2O component, 1.0% to 18.0% of a MgO component, 0% to 3.0% of a CaO component, and 0.5% to 12.0% of a TiO2 component, and a total content of the SiO2 component, the Al2O3 component, the Na2O component, the K2O component, the MgO component, and the TiO2 component is 90% or more.

Abstract: Embodiments of glass articles exhibiting a sag temperature in a range from about 600° C. to about 700° C. are disclosed. In one or more embodiments, the glass article includes a glass composition including SiO2 in an amount in a range from about 66 mol % to about 80 mol %, Al2O3 in an amount in a range from about 2 mol % to about 15 mol %, B2O3 in an amount in a range from about 0.9 mol % to about 15 mol %, P2O5 in a non-zero amount up to and including 7.5 mol %, Li2O in an amount from about 0.5 mol % to about 12 mol %, and Na2O in an amount from about 6 mol % to about 15 mol %. Laminates including the glass articles and methods for forming such laminates are also disclosed.

Abstract: The present invention relates to a boroaluminosilicate mineral material, a low temperature co-fired ceramic composite material, a low temperature co-fired ceramic, a composite substrate and preparation methods thereof. A boroaluminosilicate mineral material for a low temperature co-fired ceramic, the boroaluminosilicate mineral material comprises the following components expressed in mass percentages of the following oxides: 0.41%-1.15% of Na2O, 14.15%-23.67% of K2O, 1.17%-4.10% of CaO, 0-2.56% of Al2O3, 13.19%-20.00% of B2O3, and 53.47%-67.17% of SiO2. The aforementioned boroaluminosilicate mineral material is chemically stable; a low temperature co-fired ceramic prepared from it not only has excellent dielectric properties, but also has a low sintering temperature, a low thermal expansion coefficient, and high insulation resistance; it is also well-matched with the LTCC process and can be widely used in the field of LTCC package substrates.

Abstract: An information handling system for managing a network includes a first stackable network switch, a second stackable network switch, and a hardware switching management controller. The first stackable network switch includes a first configuration setting to enable the first stackable network switch to operate in a switch stack. The first configuration setting is accessible via an OpenFlow protocol. The second stackable network switch includes a second configuration setting to enable the second stackable network switch to operate in the switch stack. The second configuration setting is accessible via the OpenFlow protocol. The hardware switching management controller includes an OpenFlow stacking manager configured to set the first configuration setting and the second configuration setting such that the switch stack includes the first and second stackable network switches.

Abstract: Embodiments of the present disclosure pertain to crystallizable glasses and glass-ceramics that exhibit a black color and are opaque. In one or more embodiments, the crystallizable glasses and glass-ceramics include a precursor glass composition that exhibits a liquidus viscosity of greater than about 20 kPa*s. The glass-ceramics exhibit less than about 20 wt % of one or more crystalline phases, which can include a plurality of crystallites in the Fe2O3—TiO2—MgO system and an area fraction of less than about 15%. Exemplary compositions used in the crystallizable glasses and glass-ceramics include, in mol %, SiO2 in the range from about 50 to about 76, Al2O3 in the range from about 4 to about 25, P2O5+B2O3 in the range from about 0 to about 14, R2O in the range from about 2 to about 20, one or more nucleating agents in the range from about 0 to about 5, and RO in the range from about 0 to about 20.

Abstract: There is produced a Li-containing silicon oxide powder containing a crystallized lithium silicate that is mostly water-insoluble Li2Si2O5 and containing little crystalline Si. This object is attained through the mixing of a lower silicon oxide powder represented by a compositional formula SiOx (0.5<x<1.5) with a powdered lithium source that involves grinding of the powdered lithium source; controlling a median diameter D1 of the lower silicon oxide powder and a median diameter D2 of the powdered lithium source so as to fulfill 0.05?D2/D1?2; and calcining the mixed powder at 300° C. or higher and 800° C. or lower.

Abstract: A plate intended for covering or receiving induction heating elements, more particularly an induction cooking plate, said plate being a glass plate with a lithium aluminosilicate-type composition, said plate having a surface zone at least 5 ?m thick that includes potassium ions in replacement of the lithium ions of the glass. In addition, an induction cooking appliance incorporating said plate and to a method for producing said plate.

Abstract: A chemically strengthened glass having a compressive stress layer formed in a surface layer thereof according to an ion exchange method, in which a surface of the glass has polishing flaws, the glass has a texture direction index (Stdi) of 0.30 or more, a hydrogen concentration Y in a region to a depth X from an outermost surface of the glass satisfies the following relational equation (I) at X=from 0.1 to 0.4 (?m), and a surface strength F (N) measured by a ball-on-ring test is (F?1400×t2) relative to a sheet thickness t (mm) of the glass: Y=aX+b??(I) in which meanings of respective symbols in the equation (I) are as follows: Y: hydrogen concentration (as H2O, mol/L), X: depth from the outermost surface of the glass (?m), a: ?0.300 or more, and b: 0.220 or less.

Abstract: This method for estimating the depth of latent scratches in SiC substrates includes an etching step, a measurement step, and an estimation step. In the etching step, a SiC substrate in which at least the surface is formed from single crystal SiC, and which has been subjected to machining, is subjected to heat treatment under Si atmosphere to etch the surface of the SiC substrate. In the measurement step, the surface roughness or the residual stress of the SiC substrate which has been subjected to the etching step is measured. In the estimation step, the depth of latent scratches or the presence or absence of latent scratches in the SiC substrate before the etching step are estimated on the basis of the results obtained in the measurement step.

Abstract: Provided is a high-strength crystallized glass or substrate having a high visible light transmittance and a good color balance, which is suitable for use in protecting members of portable electronic devices, optical devices and the like. Provided is a crystallized glass comprising, in terms of mol % on an oxide basis: an SiO2 component of 30.0% or more and 70.0% or less, an Al2O3 component of 8.0% or more and 25.0%, an Na2O component of 0% or more and 25.0% or less, an MgO component of 0% or more and 25.0% or less, a ZnO component of 0% or more and 30.0% or less and a TiO2 component of 0% or more and 10.0% or less, the molar ratio [Al2O3/(MgO+ZnO)] having a value of 0.5 or more and 2.0 or less, and comprising one or more selected from RAl2O4, RTi2O5, R2TiO4, R2SiO4, RAl2Si2O8 and R2Al4Si5O18 as a crystal phase.

Abstract: Embodiments of this disclosure pertain to a strengthened glass article including a first surface and a second surface opposing the first surface defining a thickness (t) of about less than about 1.1 mm, a compressive stress layer extending from the first surface to a depth of compression (DOC) of about 0.1·t or greater, such that when the glass article fracture, it breaks into a plurality of fragments having an aspect ratio of about 5 or less. In some embodiments, the glass article exhibits an equibiaxial flexural strength of about 20 kgf or greater, after being abraded with 90-grit SiC particles at a pressure of 25 psi for 5 seconds. Devices incorporating the glass articles described herein and methods for making the same are also disclosed.

Abstract: A magnetic-disk glass substrate of the present invention has a pair of main surfaces, and an arithmetic mean roughness (Ra) for wavelength components of 10 to 50 nm of the surface of the main surfaces is 0.15 nm or less.

Abstract: A magnetic-disk glass substrate has a circular hole at a center, and includes a pair of main surfaces and a side wall surface orthogonal to the main surfaces. A roundness of the circular hole is 1.5 ?m or less. A difference between a maximum value and a minimum value of radii of three inscribed circles that are respectively derived from outlines in the circumferential direction at three positions spaced apart by 200 ?m in a substrate thickness direction on the side wall surface of the circular hole is 3.5 ?m or less.

Abstract: An information recording medium glass substrate and an information recording medium are provided in which a first roll-off variation and a second roll-off variation fall within the following ranges: 180 ??first roll-off variation?990 ? (condition 1) and 650 ??second roll-off variation?3700 ? (condition 2).

Abstract: A down-drawable glass ceramic. The glass ceramic has a composition which yields a liquidus viscosity that enables formation of the parent glass by down-draw techniques such as fusion-draw and slot-draw methods. The resulting glass ceramic is white or translucent in appearance with high strength achieved through heat treatment of the fusion-formed glass.

Abstract: In one embodiment, a structure for a energy storage device may include at one polycrystalline substrate. The grain size may be designed to be at least a size at which phonon scattering begins to dominate over grain boundary scattering in the polycrystalline substrate. The structure also includes a porous structure containing multiple channels within the polycrystalline substrate.

Abstract: Voltage controlled magnetic tunnel junctions and memory devices are described which provide efficient high speed switching of non-volatile magnetic devices at high cell densities. Implementations are described which provide a wide range of voltage control alternatives with in-plane and perpendicular magnetization, bidirectionally switched magnetization, and control of domain wall dynamics.

Abstract: Provided are a magnetic disk substrate and a method of manufacturing the same, wherein the magnetic disk substrate has very few defects present on its surface with an arithmetic mean roughness (Ra) at a level in the vicinity of 0.1 nm and thus is suitable as a substrate for a magnetic disk with high recording density. The magnetic disk glass substrate is such that the arithmetic mean roughness (Ra) of the main surface of the glass substrate measured using an atomic force microscope with a resolution of 256×256 pixels in a 2 ?m×2 ?m square is 0.12 nm or less and the number of defects detected to have a size of 0.1 ?m to 0.6 ?m in plan view and a depth of 0.5 nm to 2 nm is less than 10 per 24 cm2, wherein the defects are each detected using a shift in wavelength between incident light and reflected light upon irradiating and scanning helium neon laser light with a wavelength of 632 nm on the main surface of the glass substrate.

Abstract: A non-ablative method and apparatus for making an economical glass hard disk (platter) for a computer hard disk drive (HDD) using a material machining technique involving filamentation by burst ultrafast laser pulses. Two related methods disclosed, differing only in whether the glass substrate the HDD platter is to be cut from has been coated with all the necessary material layers to function as a magnetic media in a computer's hard drive. Platter blanks are precisely cut using filamentation by burst ultrafast laser pulses such that the blank's edges need not be ground, the platter's geometric circularity need not be corrected and there is no need for further surface polishing. Thus the platters can be cut from raw glass or coated glass. As a result, this method reduces the product contamination, speeds up production, and realizes great reductions in the quantity of waste materials and lower production costs.

Abstract: A glass for a magnetic recording medium substrate permitting the realization of a magnetic recording medium substrate affording good chemical durability and having an extremely flat surface, a magnetic recording medium substrate comprised of this glass, a magnetic recording medium equipped with this substrate, and methods of manufacturing the same. The glass is an oxide glass not including As or F.

Abstract: The shape and number of surface defects are controlled so that the occurrence of failure is suppressed in an HDD device in which a magnetic head with a very small flying height, such as a DFH head, is mounted. A magnetic disk substrate is characterized in that when laser light with a wavelength of 405 nm and a laser power of 25 mW is irradiated with a spot size of 5 ?m and scattered light from the substrate is detected, the number of defects detected to have a size of 0.1 ?m to not more than 0.3 ?m is less than 50 per 24 cm2 and, with respect to the defects, there is no defect in which, in a bearing curve obtained by a bearing curve plot method using an atomic force microscope, a portion from an apex of the defect to 45% thereof is located in an area of defect height higher than a virtual line connecting from the apex of the defect to 45% thereof.

Abstract: An aspect of the present invention relates to glass for a magnetic recording medium substrate, which includes essential components in the form of SiO2, Li2O, Na2O, and one or more alkaline earth metal oxides selected from the group consisting of MgO, CaO, SrO, and BaO, wherein a molar ratio of a content of MgO to a combined content of MgO, CaO, SrO, and BaO (MgO/(MgO+CaO+SrO+BaO)) is equal to or greater than 0.80, and which has a Young's modulus of equal to or greater than 80 GPa, and a glass transition temperature of equal to or greater than 620° C.

Abstract: The present invention provides a glass substrate for magnetic disk in which surface irregularity of a principal surface is suppressed and a method for efficiently manufacturing a glass substrate for magnetic disk. The method includes the steps of: forming a sheet glass material by performing press forming to molten glass, a principal surface of the sheet glass material having target flatness for the glass substrate for magnetic disk, the sheet glass material having a surface shape to be ground using a grinding abrasive grain; grinding the sheet glass material using a fixed abrasive grain; and polishing the sheet glass material using a loose abrasive grain, the sheet glass material having surface irregularity of the principal surface ground using the fixed abrasive grain.

Abstract: It is an object to provide a magnetic disk substrate highly reliable to prevent the occurrence of crash failure even if a magnetic disk is rotated at high speed, and suitable for a hard disk that starts and stops by the load/unload method, and a magnetic disk using such a substrate. The representative structure of a magnetic disk substrate is a disk-shaped glass substrate 10 having a generally flat main surface 11, an end face 12, a chamfered face 13 formed between the main surface 11 and the end face 12, and an offset portion, at the periphery of the main surface 11, raised or lowered with respect to a flat surface, other than the periphery, of the main surface 11, and characterized in that the magnitude of the offset portion is approximately uniform over the entire circumference of the glass substrate 10.

Abstract: An enlarged substrate for a magnetic recording medium used in a data storage device such as a hard disc drive (HDD). In some embodiments, an apparatus includes a substrate for a magnetic recording disc for installation in a 3½ inch form factor hard disc drive, the substrate having an overall diameter of nominally from 96.9 mm to 100.4 mm. In other embodiments, an apparatus comprises a substrate for a magnetic recording disc for installation in a 2½ inch form factor hard disc drive, the substrate having an overall diameter of nominally from 66.9 mm to 71.8 mm. In other embodiments, a data storage device has a magnetic recording medium that uses an enlarged substrate as set forth above.

Abstract: A manufacturing method of a glass substrate for a magnetic disk is provided whereby nano pits and/or nano scratches cannot be easily produced in polishing a principal face of a glass substrate using a slurry containing zirconium oxide as an abrasive. The manufacturing method of a glass substrate for a magnetic disk includes, for instance, a polishing step of polishing a principal face of a glass substrate using a slurry containing, as an abrasive, zirconium oxide abrasive grains having monoclinic crystalline structures (M) and tetragonal crystalline structures (T).

Abstract: A substrate for a magnetic recording medium having a disc shape with a central hole is provided in which the surface roughness of the principal surface of the substrate is 1 angstrom or less in terms of root mean square roughness (Rq) when a space period (L) of an undulation in the circumferential direction is in the range 10 to 1,000 ?m, and in which when a component in the vertical axis direction of a line segment Z connecting a point A with the space period (L) of 10 ?m and a point B with the space period (L) of 1,000 ?m in a curve S marked on a double logarithmic graph which is obtained by analyzing the surface roughness using a spectrum and in which the horizontal axis is set to the space period (L) (?m) and the vertical axis is set to the power spectrum density (PSD) (k·angstrom2·?m) (where k is a constant) is defined as H and a displacement at which the component in the vertical axis direction of the curve S is the maximum with respect to the line segment Z is defined as ?H, a value (P) expressed by (?

Abstract: For an information storage medium a glass substrate is produced in a method including the steps of: polishing a glass substrate with a polishing agent applied thereon; and subsequently, chemically strengthening a major surface of the glass substrate. The polishing agent contains cerium oxide at a purity equal to or larger than 99% by mass for CeO2/TREO, and has an alkaline earth metal content having a total mass equal to or smaller than 10 ppm by mass. The step of polishing is performed with a soft polishing pad to polish the glass substrate.

Abstract: An ion-exchanged glass article manufacturing method includes an ion-exchange step of bringing a glass article with a composition containing Li into contact with a molten salt dissolved solution containing an alkali metal element having an ionic radius larger than an ionic radius of the Li contained in the glass article, thereby ion-exchanging the Li in the glass article with the alkali metal element in the molten salt dissolved solution. At least one kind of additive selected from the group consisting of NaF, KF, K3AlF6, Na2CO3, NaHCO3, K2CO3, KHCO3, Na2SO4, K2SO4, KAl(SO4)2, Na3PO4, and K3PO4 is added to the molten salt dissolved solution so that the ion-exchange step is carried out while the additive is in a solid state.

Abstract: Provided is a method of manufacturing a magnetic disk glass substrate, wherein, in a main surface polishing process, main surface polishing is applied to one of main surfaces of a glass substrate so that the one main surface has a predetermined arithmetic mean roughness, and main surface polishing is applied to the other main surface of the glass substrate so that the other main surface has a roughness which is higher than the arithmetic mean roughness (Ra) of the one main surface and which is low enough to prevent a component forming the magnetic disk glass substrate from being eluted from the other main surface.

Abstract: A glass for use in chemical reinforcement for use in a substrate of an information recording medium, having a composition comprising, denoted as mol %: SiO2 47 to 70%? Al2O3 1 to 10% (where the total of SiO2 and Al2O3 is 57 to 80%) CaO 2 to 25% BaO 1 to 15% Na2O 1 to 10% K2O 0 to 15% (where the total of Na2O and K2O is 3 to 16%) ZrO2 1 to 12% MgO 0 to 10% SrO 0 to 15% (where the ratio of the content of CaO to the total of MgO, CaO, SrO, and BaO is greater than or equal to 0.5) ZnO 0 to 10% (where the total of MgO, CaO, SrO, BaO, and ZnO is 3 to 30%) TiO2 0 to 10% and the total content of the above-stated components is greater than or equal to 95%. A glass for use in chemical reinforcement for use in the substrate of an information recording medium employed in a perpendicular magnetic recording system, in which the glass exhibits the glass transition temperature is greater than or equal to 600° C.

Abstract: According to one aspect of the present invention, provided is glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, a total of 70 to 85 percent of SiO2 and Al2O3, where SiO2 content is equal to or greater than 50 percent and Al2O3 content is equal to or greater than 3 percent; a total of equal to or greater than 10 percent of Li2O, Na2O and K2O; a total of 1 to 6 percent of CaO and MgO, where CaO content is greater than MgO content; a total of greater than 0 percent but equal to or lower than 4 percent of ZrO2, HfO2, Nb2O5, Ta2O5, La2O3 Y2O3 and TiO2; with the molar ratio of the total content of Li2O, Na2O and K2O to the total content of SiO2, Al2O3, ZrO2, HfO2, Nb2O5, Ta2O5, La2O3, Y2O3 and TiO2 ((Li2O+Na2O+K2O)/(SiO2+Al2O3+ZrO2+HfO2+Nb2O5+Ta2O5+La2O3+Y2O3+TiO2)) being equal to or less than 0.28.

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 manufacturing method of a sheet glass material for magnetic disk, the method includes, dropping process for dropping a lump of molten glass; pressing process for sandwiching simultaneously the lump from both sides of the dropping path of the lump with surfaces of a pair of dies facing together, and performing press forming to the lump to obtain a sheet glass material, wherein at least one of the pair of dies has a concave shape with respect to the dropping path of the lump.

Abstract: Provided are a magnetic disk substrate and a method of manufacturing the same, wherein the magnetic disk substrate has very few defects present on its surface with an arithmetic mean roughness (Ra) at a level in the vicinity of 0.1 nm and thus is suitable as a substrate for a magnetic disk with high recording density. The magnetic disk glass substrate is such that the arithmetic mean roughness (Ra) of the main surface of the glass substrate measured using an atomic force microscope with a resolution of 256×256 pixels in a 2 ?m×2 ?m square is 0.12 nm or less and the number of defects detected to have a size of 0.1 ?m to 0.6 ?m in plan view and a depth of 0.5 nm to 2 nm is less than 10 per 24 cm2, wherein the defects are each detected using a shift in wavelength between incident light and reflected light upon irradiating and scanning helium neon laser light with a wavelength of 632 nm on the main surface of the glass substrate.

Abstract: An aspect of the present invention relates to glass for a magnetic recording medium substrate, which includes essential components in the form of SiO2, Li2O, Na2O, and one or more alkaline earth metal oxides selected from the group consisting of MgO, CaO, SrO, and BaO, wherein a molar ratio of a content of MgO to a combined content of MgO, CaO, SrO, and BaO (MgO/(MgO+CaO+SrO+BaO)) is equal to or greater than 0.80, and which has a Young's modulus of equal to or greater than 80 GPa, and a glass transition temperature of equal to or greater than 620° C.

Abstract: The present invention relates to a method for manufacturing a glass substrate for an information recording medium having a high level of cleanness and superior smoothness. The manufacturing method includes a step for washing a disk-shaped glass plate with an acid washing liquid, a step for removing at least part of a surface layer, which is formed on the surface of the glass plate, by performing grinding with diamond abrasion grains, and a step for washing the surface with a neutral or alkaline washing liquid.

Abstract: The shape and number of surface defects are controlled so that the occurrence of failure is suppressed in an HDD device in which a magnetic head with a very small flying height, such as a DFH head, is mounted. A magnetic disk substrate is characterized in that when laser light with a wavelength of 405 nm and a laser power of 25 mW is irradiated with a spot size of 5 ?m and scattered light from the substrate is detected, the number of defects detected to have a size of 0.1 ?m to not more than 0.3 ?m is less than 50 per 24 cm2 and, with respect to the defects, there is no defect in which, in a bearing curve obtained by a bearing curve plot method using an atomic force microscope, a portion from an apex of the defect to 45% thereof is located in an area of defect height higher than a virtual line connecting from the apex of the defect to 45% thereof.

Abstract: A magnetic recording medium includes, in a main surface of a glass substrate on which a magnetic recording layer is formed, a plurality of annular first thermally-conductive regions having a larger thermal conductivity than the glass substrate that are provided concentrically with the glass substrate. The first thermally-conductive regions are each provided so that it extends across a plurality of tracks. The first thermally-conductive region has a radial width larger than a depth, from the main surface, of the first thermally-conductive region.

Abstract: A method for forming a glass substrate comprises the steps of forming a glass blank with opposing substantially planar surfaces and at least one edge, coating the glass blank in silica-alumina nanoparticles, the silica-alumina nanoparticles comprising an inner core of silica with an outer shell of alumina, annealing the coated glass blank to form a conformal coating of silica-alumina around the glass blank, and polishing the coated glass blank to remove the conformal coating of silica-alumina from the opposing substantially planar surfaces thereof.

Abstract: According to one aspect of the present invention, provided is glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, a total of 70 to 85 percent of SiO2 and Al2O3, where SiO2 content is equal to or greater than 50 percent and Al2O3 content is equal to or greater than 3 percent; a total of equal to or greater than 10 percent of Li2O, Na2O and K2O; a total of 1 to 6 percent of CaO and MgO, where CaO content is greater than MgO content; a total of greater than 0 percent but equal to or lower than 4 percent of ZrO2, HfO2, Nb2O5, Ta2O5, La2O3 Y2O3 and TiO2; with the molar ratio of the total content of Li2O, Na2O and K2O to the total content of SiO2, Al2O3, ZrO2, HfO2, Nb2O5, Ta2O5, La2O3, Y2O3 and TiO2 ((Li2O+Na2O+K2O)/(SiO2+Al2O3+ZrO2+HfO2+Nb2O5+Ta2O5+La2O3+Y2O3+TiO2)) being equal to or less than 0.28.

Abstract: Provided are a magnetic disk substrate and a method of manufacturing the same, wherein the magnetic disk substrate has very few defects present on its surface with an arithmetic mean roughness (Ra) at a level in the vicinity of 0.1 nm and thus is suitable as a substrate for a magnetic disk with high recording density. The magnetic disk glass substrate is such that the arithmetic mean roughness (Ra) of the main surface of the glass substrate measured using an atomic force microscope with a resolution of 256×256 pixels in a 2 ?m×2 ?m square is 0.12 nm or less and the number of defects detected to have a size of 0.1 ?m to 0.6 ?m in plan view and a depth of 0.5 nm to 2 nm is less than 10 per 24 cm2, wherein the defects are each detected using a shift in wavelength between incident light and reflected light upon irradiating and scanning helium neon laser light with a wavelength of 632 nm on the main surface of the glass substrate.

Abstract: The present invention relates to a method for manufacturing a glass substrate for an information recording medium having a high level of cleanness and superior smoothness. The manufacturing method includes a step for washing a disk-shaped glass plate with an acid washing liquid, a step for removing at least part of a surface layer, which is formed on the surface of the glass plate, by performing grinding with diamond abrasion grains, and a step for washing the surface with a neutral or alkaline washing liquid.

Abstract: The present invention provides a method for efficiently manufacturing a glass substrate for magnetic disk having good accuracy of a surface irregularity and an impact resistance. The method includes the steps of: performing press forming to molten glass to prepare a sheet glass material, the sheet glass material having a roughness of the principal surface of 0.01 ?m or less and target flatness of a glass substrate for magnetic disk; chemically strengthening the sheet glass material by dipping the sheet glass material in a chemically strengthening salt, thereby preparing a disk substrate; polishing the principal surfaces of the disk substrate. A thickness of the sheet glass material prepared in the press forming step is larger than a target thickness of the glass substrate for magnetic disk by a polishing quantity of the principal surface polishing step.

Abstract: The shape and number of surface defects are controlled so that the occurrence of failure is suppressed in an HDD device in which a magnetic head with a very small flying height, such as a DFH head, is mounted. A magnetic disk substrate is characterized in that when laser light with a wavelength of 405 nm and a laser power of 25 mW is irradiated with a spot size of 5 ?m and scattered light from the substrate is detected, the number of defects detected to have a size of 0.1 ?m to not more than 0.3 ?m is less than 50 per 24 cm2 and, with respect to the defects, there is no defect in which, in a bearing curve obtained by a bearing curve plot method using an atomic force microscope, a portion from an apex of the defect to 45% thereof is located in an area of defect height higher than a virtual line connecting from the apex of the defect to 45% thereof.