Abstract: Transparent oxynitride glass has transmittance of at least 80%/mm in a wavelength region of 400 to 800 nm, with Si particles or Si alloy particles of not more than 1.0.times.10.sup.9 /cm.sup.3 in number. Glass fiber prepared by drawing this glass can attain strength which is by far superior to that of conventional oxide glass fiber, to be preferably applied to reinforcing fiber.

Abstract: The invention relates to an oxynitride glass fiber for composite products which has a surface cladding formed from a composition containing a silane coupling agent. This fiber is excellent in strength, elastic modulus, adhesion and wetting property with respect to matrix resin. A composite product comprising the above clad oxynitride glass fiber and a thermaplastic or thermosetting resin matrix is also disclosed. This composite is excellent in strength, elastic modulus, toughness and interlaminar shear resistance.

Abstract: A fiber-reinforced metal comprising glass fibers and a matrix metal, said glass fibers having a nitrogen content of at least 8 atomic %. The fiber-reinforced metal has a high tensile strength and elasticity.

Abstract: A sol-gel process for preparing dimensionally precise tubular silica glass articles wherein a solution having a specific gravity higher than the specific gravity of the sol solution is placed in a cylindrical container with the sol solution is provided. The container is rotated around its axis and the high specific gravity solution becomes aligned adjacent the inner wall of the cylindrical container due to the effect of centrifugal forces acting on the high specific gravity solution. The sol solution becomes aligned adjacent the inner surface of the high specific gravity solution. The tubular wet gel formed from the sol solution has a uniform thickness and a highly precise round cross-section. The dimensional precision of the wet gel is maintained by rotating the wet gel during drying in order to prevent warping.

Abstract: A sol-gel method of preparing doped glass articles is provided. The glass is formed by preparing a sol solution containing hydrolyzed silicon alkoxide and ultrafine particle silica. The sol solution can also include a dopant. The sol solution is gelled in a container, dried and sintered to yield the doped silica glass articles.

Abstract: A method of preparing tubular silica glass is disclosed. The method includes the steps of first hydrolyzing silicon alkoxide with acid and then adding ultra-fine particle silica to form a sol solution. The sol solution is placed in a cylindrical container and gelled while rotating the cylindrical container to obtain a tubular gel. The tubular gel is dried and sintered to the tubular silica glass.

Abstract: A method of preparing preforms for optical fibers is provided. The method includes preparation of a first sol solution of a silicon alkoxide hydrolyzed with an acid and ultrafine particle silica, placement of the first sol solution into a container, and gelation of the first sol solution while the container is being rotated to yield a wet gel having a center hole. A second sol solution having a different composition than the first sol solution is prepared and used to fill the center hole in the wet gel. The second sol solution is then gelled to a wet gel composite and the composite is dried and sintered to yield the preform.

Abstract: A method for preparing high quality silica glass articles is provided. The glass is prepared by hydrolyzing silicon alkoxide with a basic reagent to yield a first solution, hydrolyzing a silicon alkoxide with an acid reagent to yield a second solution, mixing the first solution with the second solution at a predetermined mixing rate to yield a sol solution, pouring the sol solution into a container, gelling the sol solution to a wet gel, drying the wet gel to a dry gel, and sintering the dry gel to yield a silica glass.