Abstract: Low-boron, high-barium glass compositions and fine-diameter glass fibers for forming clean room HEPA and ULPA filters, are provided. The compositions and resulting glass fibers preferably comprise a low concentration, less than about 1 weight percent, of boric oxide, a relatively high concentration of barium, such as from about 5.5 to about 18 weight percent barium oxide, and a concentration of alkali oxide ranging from about 10 to about 14.5 weight percent. Alumina is preferably present in the glass fiber compositions and the resulting glass fibers in a range of from about 4 weight percent to about 8 weight percent, and calcium oxide and magnesium oxide are preferably present in a range of from about 1 weight percent to about 6 weight percent and from about 0 weight percent to about 3.5 weight percent, respectively. The glass fiber compositions also preferably include from about 2 to about 6 weight percent zinc oxide, from about 0.1 to about 1.

Abstract: Low-boron, high-barium glass compositions and fine-diameter glass fibers for forming clean room HEPA and ULPA filters, are provided. The compositions and resulting glass fibers preferably comprise a low concentration, less than about 1 weight percent, of boric oxide, a relatively high concentration of barium, such as from about 5.5 to about 18 weight percent barium oxide, and a concentration of alkali oxide ranging from about 10 to about 14.5 weight percent. Alumina is preferably present in the glass fiber compositions and the resulting glass fibers in a range of from about 4 weight percent to about 8 weight percent, and calcium oxide and magnesium oxide are preferably present in a range of from about 1 weight percent to about 6 weight percent and from about 0 weight percent to about 3.5 weight percent, respectively. The glass fiber compositions also preferably include from about 2 to about 6 weight percent zinc oxide, from about 0.1 to about 1.

Abstract: Low-boron, high-barium glass compositions and fine-diameter glass fibers for forming clean room HEPA and ULPA filters, are provided. The compositions and resulting glass fibers preferably comprise a low concentration, less than about 1 weight percent, of boric oxide, a relatively high concentration of barium, such as from about 5.5 to about 18 weight percent barium oxide, and a concentration of alkali oxide ranging from about 10 to about 14.5 weight percent. Alumina is preferably present in the glass fiber compositions and the resulting glass fibers in a range of from about 4 weight percent to about 8 weight percent, and calcium oxide and magnesium oxide are preferably present in a range of from about 1 weight percent to about 6 weight percent and from about 0 weight percent to about 3.5 weight percent, respectively. The glass fiber compositions also preferably include from about 2 to about 6 weight percent zinc oxide, from about 0.1 to about 1.

Abstract: A glass composition specially useful in the glass envelope of TV receiver tubes and which is of the lead silicate type is disclosed comprising in weight percent 30-65% SiO.sub.2, 20-40% PbO, 5-20% alkali metal oxides, 0-2% Al.sub.2 O.sub.3, 0-10% alkaline earth metal oxides, 0.2-2% Sb.sub.2 O.sub.3, and 0.1-0.5% CeO.sub.2. The improvement resides in employment of a novel refining system when the glass is formed which employs Sb.sub.2 O.sub.3, niter and CeO.sub.2 as the refining agents in particular weight proportions to reduce the seed count in the molten glass while also reducing thermal shock breakage when the solid glass product is thereafter thermally reworked.

Abstract: A glass composition specially useful in the glass envelope of TV receiver tubes and which is of the lead silicate type is disclosed comprising in weight percent 30-65% SiO.sub.2, 20-40% PbO, 5-20% alkali metal oxides, 0-2% Al.sub.2 O.sub.3, 0-10% alkaline earth metal oxides, 0.2-2% Sb.sub.2 O.sub.3, and 0.1-0.5% CeO.sub.2. The improvement resides in employment of a novel refining system when the glass is formed which employs Sb.sub.2 O.sub.3, niter and CeO.sub.2 as the refining agents in particular weight proportions to reduce the seed count in the molten glass while also reducing thermal shock breakage when the solid glass product is thereafter thermally reworked.

Abstract: Addition of from about 1.0 to about 15% by weight of a vanadium oxide or boric oxide promoter to a zirconia (ZrO.sub.2) powder promotes rapid densification at temperatures below about 1300.degree. C. For example, a density of greater than 92% of estimated theoretical density can be achieved by addition of 4% by weight of ZrV.sub.2 O.sub.7 to monoclinic ZrO.sub.2 and sintering at 1100.degree. C. for about 24 hours. Sintering at temperatures below about 1150.degree. C. avoids the destructive monoclinic/tetragonal phase transformation and provides for better control of microstructure and composition. A density of greater than 98% of estimated theoretical density can be achieved by addition of from about 2 to about 5% by weight of a boric oxide promoter to stabilized cubic ZrO.sub.2 and sintering at about 1200.degree. C. for about 4 hours.

Abstract: Glass compositions with a particularly high alkali resistance comprise, in weight percentages:______________________________________ SiO.sub.2 45 to 65% ZrO.sub.2 6 to 20% RO 20 to 45% ______________________________________The total of SiO.sub.2 + ZrO.sub.2 + RO being not less than 94% by weight of the glass, where RO represents CaO, in an amount from 20 to 45%, with or without lesser amounts of further divalent oxides of the group consisting of MgO, SrO, BaO and ZnO, the balance (if any) of the composition consisting of compatible constituents such as TiO.sub.2, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, Fe.sub.2 O.sub.3, F.sub.2 and R.sub.2 O, where R.sub.2 O represents K.sub.2 O, Na.sub.2 O or Li.sub.2 O, the amount of any one of these compatible constituents not exceeding 5% by weight. Preferably R.sub.2 O does not exceed 3%.