Abstract: A number of unique processes are disclosed for manufacture of sintered high-purity quartz glass products in which a shaped silica body or preform is made from an aqueous slurry of micronized silica particles by gel casting, slip casting or electrophoretic deposition. The silica particles may comprise a major portion by weight of crystalline silica. In one embodiment of the invention the sintered quartz glass is transparent, substantially bubble-free and suitable for scientific or optical uses. In another embodiment the porous silica preform is fired in steam to increase the hydroxyl content and then nitrided in a nitrogen-hydrogen reducing atmosphere. A minute amount of chemically-combined nitrogen in the high-purity quartz glass is sufficient to provide a tremendous improvement in physical properties and an incredible increase in the resistance to devitrification.

Abstract: A magnetic recording medium comprises a nonmagnetic substrate (1) of a crystallizable material and a lamina including at least a magnetic layer (3) formed thereon. The nonmagnetic substrate has a surface specified by a predetermined crystal grain size while the magnetic layer (3) has a magnetic crystal grain size dependent on the predetermined crystal size. The lamina may include an underlying layer (2) which is formed between the nonmagnetic substrate (1) and the magnetic layer (3) and which has a thickness selected to control the magnetic crystal grain size of the magnetic layer (3). The lamina may further comprise an intermediate layer (6) formed between the underlying layer (2) and the magnetic layer (3). Alternatively, an initial layer (7) may be formed between the nonmagnetic substrate (1) and the underlying layer (2).

Abstract: SiO2—TiO2 glasses having a low coefficient of thermal expansion are produced by a molding being produced that consists of SiO2 powder, SiO2—TiO2 powder or TiO2 powder and that contains by way of secondary component a titanium-containing component which is converted into amorphous TiO2.

Abstract: The method of making a curved glass-ceramic panel by bending a green glass panel to be ceramicized avoids formation of stresses in the bending zone. The method includes performing the bending process in a heated chamber at a temperature of from 10° C. to 50° C. above a transformation temperature of the green glass panel to be bent; providing a forming body acting as a workpiece support (3) with a geometric shape according to a bend geometry of the glass-ceramic panel and tempering the forming body at the temperature of the heated chamber; bringing the forming body into effective mechanical contact with the green glass panel in a bending zone of the green glass panel to form a curved green glass panel and ceramicizing the curved green glass panel to form the curved glass-ceramic panel.

Abstract: A polished glass disk medium substrate suitable for use as a substrate for a hard disk, a hard disk containing the substrate and methods for making the substrate. The substrate containing glass forming raw materials may be formed so as to have a Young's modulus of 110 or higher.

Abstract: The present invention relates to a process and apparatus to cast and form slag directly from the molten state into crystalline or amorphous products suitable for use as decorative and structural building and construction materials. Molten slag and additives are refined at high temperature in a treatment furnace for a period of hours. The eventual entrapped gas content is controlled using a variety of methods, such as vacuum pressures and bottom stirring with inert gas. The molten slag is cast directly into moulds, and these moulds form the slag into any shape desired. The formed products are immediately introduced into a heat treatment furnace at temperatures at or above the glass transition temperature (GTT) for the case of crystalline products, or just below the GTT for amorphous products. The product is thermally cycled over a period of hours to relieve thermal stresses during cooling to ambient temperatures.

Abstract: A glass-ceramic which is substantially and desirably totally transparent, and which contains a willemite predominant crystal phase within the ternary Mg2SiO4—Zn2SiO4—Li4SiO4 system. The glass-ceramic is formed from precursor glasses having the following compositions, in weight percent on an oxide basis, of 25-60 SiO2, 4-20 Al2O3, 20-55 ZnO, 0-12 MgO, 0-18 K2O, 0-12 Na2O, 0-30 GeO2, with the condition that &Sgr;K2O+Na2O≧5. The glass-ceramic may be doped with up to 1 wt. % Cr2O3 to impart optical activity thereto.

Abstract: An efficient method is proposed for the utilization of heretofore useless extremely fine fluffy silica particles obtained as a flue dust in the flame-hydrolysis of vaporizable silicon compound in an oxyhydrogen flame in the manufacturing process of fused silica glass. The method comprises the steps of (a) uniformly mixing the silica particles with water, (b) drying the wet mixture under specified conditions to give dried cakes of the silica particles, (c) disintegrating the dried cakes into porous silica beads having an appropriate particle diameter, (d) semi-sintering the porous silica beads at 800 to 1300° C. and (e) vitrifying the semi-sintered silica beads at 1350 to 1550° C. into vitrified poreless silica glass particles which can be used as a base material for the production of fused silica glass articles.

Abstract: A composite material has a quartz glass phase and a complex compound phase compounded with the quartz glass phase, which is made of one or more compounds selected from a group of silicon carbide, silicon nitride, silicon, titanium nitride and titanium carbide, as a main ingredient. The composite material can be used instead of quartz glass, and can prevent the generations of microcrack, tipping and particles after the mechanical working.

Abstract: The present invention relates to a glass matrix which includes 4-70 wt. % SiO2, 0.5-20 wt. % Al2O3, 0-20 wt. % R2O, 0-30 wt. % R′O, 8-85 wt. % Ta2O5, 0-40 wt. % Nb2O5, and 0.01-1.0 wt. % R″2O3, where R2O+R″O is between about 2-35 wt. %, Ta2O5+Nb2O5 is between about 8-85 wt. %, R is selected from a group consisting of Li, Na, K, and combinations thereof, R′ is selected from a group consisting of Ba, Sr, Ca, Mg, Zn, Pb, and combinations thereof, and R″ is a rare earth element. The present invention also relates to use of the glass matrix in forming optic waveguides such as optic amplifiers. The present invention further relates to a transparent glass ceramic that contains pyrochlore, perovskite, or a combination thereof as its major crystal phase, and includes 4-40 wt. % SiO2, 1-15 wt. % Al2O3, 0-20 wt. % K2O, 0-12 wt. % Na2O, 0-5 wt. % Li2O, 8-85 wt. % Ta2O5, and 0-45 wt. % Nb2O5, wherein Ta2O5+Nb2O5 is at least about 20 wt.

Abstract: An athernal optical device and a method for producing the device, such as an athermal optical fiber reflective grating, are described. The athermal optical fiber reflective grating device comprises a negative expansion substrate, an optical fiber mounted on the substrate surface, and a grating defined in the optical fiber. The method for producing the athermal optical fiber reflective grating device comprises providing a negative expansion substrate, mounting an optical fiber with at least one reflective grating defined therein onto the substrate upper surface, and affixing the optical fiber to the substrate at at least two spaced apart locations.

Abstract: A luminous glass ceramic comprising, in percent by weight, the following components: SiO2  50-65 (%) P2O5   0-10 Al2O3  18-30 Li2O   2-6 MgO 0.2-6 ZnO   0-2 CaO   0-4 BaO 0.5-6 TiO2   1-4 ZrO2   1-4 As2O3 + Sb2O3   0-2 wherein a total amount of SiO2 and P2O5 is 50-70 wt. %, a ratio of P2O5 to SiO2 is 0-0.18, a ratio of Al2O3 to SiO2 is 0.30-0.55, one or more rare earth elements are added to the glass ceramic on an oxide basis of 0.1-30 wt. % to an total amount of other components, Na2O component, K2O component, and PbO component are not essentially contained, and the glass ceramic has a thermal shock resistance |&Dgr;t|° C.

Abstract: The present invention relates to: a method of bending the perimeter of at least one opening (2) provided in a glass-ceramic precursor plate (1), said perimeter describing a closed curve without sharp angles; a method of manufacturing a glass-ceramic plate (10′, 10″) in which at least one opening (2) is provided, whose perimeter describing a closed curve without sharp angles is bent; novel glass-ceramic plates (10′, 10″), obtainable by implementing said manufacturing methods.