Abstract: When molten glass which is under an atmosphere of pressure P, is fed into a vacuum chamber capable of rendering a pressure to the molten glass to be in a range of 38 [mmHg]-(P-50) [mmHg] to perform degassing to the molten glass, a staying time of the molten glass in the vacuum chamber is in a range of 0.12-4.8 hours, whereby there is obtainable an effective degassing function to the molten glass.

Abstract: A vacuum degassing apparatus for molten glass according to the present invention comprises a vacuum housing where a vacuum is created; a vacuum degassing vessel housed in the vacuum housing to degas the molten glass; an introduction device communicated to the vacuum degassing vessel so as to introduce untreated molten glass into the vacuum degassing vessel, or preferably an uprising pipe; and a discharge device to discharge treated molten glass from the vacuum degassing vessel, or preferably a downfalling pipe. In the apparatus, at least a portion of at least one of the vacuum degassing vessel, the uprising pipe and the downfalling pipe that directly contact with the molten glass is constituted by refractory material having a porosity of not greater than 5%. The apparatus can increase quantity of flow of the molten glass and consequently a degassing throughput of the molten glass in comparison with prior art, having the same size and the same pressure loss.

Abstract: When molten glass which is under an atmosphere of pressure P, is fed into a vacuum chamber capable of rendering a pressure to the molten glass to be in a range of 38 [mmHg]-(P-50) [mmHg] to perform degassing to the molten glass, a staying time of the molten glass in the vacuum chamber is in a range of 0.12-4.8 hours, whereby there is obtainable an effective degassing function to the molten glass.

Abstract: When molten glass which is under an atmosphere of pressure P, is fed into a vacuum chamber capable of rendering a pressure to the molten glass to be in a range of 38 [mmHg]-(P-50) [mmHg] to perform degassing to the molten glass, a staying time of the molten glass in the vacuum chamber is in a range of 0.12-4.8 hours, whereby there is obtainable an effective degassing function to the molten glass.

Abstract: A vacuum degassing apparatus for molten glass includes a vacuum housing where a vacuum is created; a vacuum degassing vessel housed in the vacuum housing to degas the molten glass; an introduction device communicated to the vacuum degassing vessel so as to introduce untreated molten glass into the vacuum degassing vessel, or preferably an uprising pipe; and a discharge device to discharge treated molten glass from the vacuum degassing vessel, or preferably a downfalling pipe. In the apparatus, at least a portion of at least one of the vacuum degassing vessel, the uprising pipe and the downfalling pipe that directly contact the molten glass is constituted by refractory material having a porosity of not greater than 5%. The apparatus can increase quantity of flow of the molten glass and consequently a degassing throughput of the molten glass, having the same size and the same pressure loss.

Abstract: A glass substrate for plasma display panel, which has a spectral transmittance of at least 87% in the range of from 400 nm to 700 nm at a thickness in the range of from 1.5 to 3.5 mm.

Abstract: A cathode ray tube has an insulating layer formed at at least a part of the outer surface of a neck tube.The insulating layer is a layer obtained by coating and baking a sol prepared by dispersing one or two or more metal alkoxides and metal salts in a hydrophilic oligomer state by adding water and an acid to a solution having one or two or more metal alkoxides and metal salts dissolved in an organic solvent such as an alcohol.

Abstract: A process for producing silica glass fibers comprising:a step of preparing a silica glass fiber spinning solution by adding a polymerization regulator to a silica sol solution obtained by the hydrolysis and condensation of a silicon alkoxide in the presence of an acid catalyst;a step of spinning the spinning solution into gel fibers by extruding the spinning solution from nozzles;a step of applying an oiling agent containing substantially no water or lower alcohol to the gel fibers;a step of forming a fiber cake by winding the oiled gel fibers on a tube or bobbin;a step of aging the gel fibers constituting the fiber cake;a step of sintering the gel fibers unwound from the fiber cake after the aging step, to form silica glass fibers.

Abstract: A spherical silica glass powder particle having projections of network pattern on its surface is produced by gel-route formation.

Abstract: A sealing glass composition containing refractory filler of lower coefficient of thermal expansion for use in sealing alumina package for electronic components is disclosed. The composition consists essentially of low melting glass powder and cordierite powder in proportion of 2-30% by weight of the total composition, and optionally, .beta.-eucryptite, .beta.-spodumen, lead titanate or zircon in a proportion, respectively, not exceeding 15% by weight of the total composition. The low melting glass has a composition of 77.0-86.0 wt. % of PbO, 6.0-15.0 wt. % of B.sub.2 O.sub.3, 0.5-6.9 wt. % of ZnO, 0.1-3.0 wt. % of SiO.sub.2, 0-3.0% of Al.sub.2 O.sub.3 0-2.0% of alkali earth metal oxide, 0-1.5% of SnO.sub.2 and 0-1.0% of alkali metal oxide.