Patent GB-969782-A (GB)
Title: High temperature resistant vitreous material and method for producing same
IPC: C03C3/06
Filed: 1961-08-03
Abstract: A silica body in the form of fibre, flake or foam and of at least 90% purity and substantially free of any fluxing ingredient, has a surface coating of at least one compound selected from the group consisting of the silicates, oxides and compounds convertible by heat to oxides of the metals chromium, aluminium, zirconium, titanium, beryllium and magnesium, the coating constituting at least 3% by weight of the coated body. The fibre, flake or foam is preferably initially of a glass comprising in weight per cent SiO2 52.9; Al2O3 13.8; CaO 21.2; B2O3 9.1; TiO2 0.6; Na2O + K2O 0.5; Fe2O3 0.3; F2 1.4 and traces of mgO and MnO.  The fibres may then be woven into a tape or made into paper and the body in the form of fibre, flake, foam, tape or paper leached as by dilute HCl and fired to give a high content of silica.  The body is then immersed in the solution or solutions to give the required coating, dried and then heated. Examples, other than the direct immersion in the metal oxide or silicate, are immersion in salts of the metals such as sulphates, chlorides, oxalates, formates, lactates or acetates followed by immersion in an hydroxide solution, preferably ammonium hydroxide, or a silicic acid solution, resulting in a gelatinous coating of the metal hydroxide or silicate, the hydroxide being converted to the oxide by heating.  Particular examples are given.ALSO:A silica body in the form of fibre, flake or foam and of at least 90% purity and substantially free of any fluxing ingredient, has a surface coating of at least one compound selected from the group consisting of the silicates, oxides and compounds convertible by heat to oxides of the metals chromium, aluminium, zirconium, titanium, beryllium and magnesium, the coating constituting at least 3% by weight of the coated body. The fibre, flake or foam is preferably initially of a glass comprising in weight per cent SiO2 52,9; Al2O3 13,8; CaO 21,2; B2O3 9,1; TiO2 0,6; Na2O+K2O 0,5; Fe2O3 0,3; F2 1,4 and traces of MgO and MnO.  The fibres may then be woven into a tape or made into paper and the body in the form of fibre, flake, foam, tape or paper leached as by dilute HCl and fired to give a high content of silica.  The body is then immersed in the solution or solutions to give the required coating, dried and then heated.  Examples, other than the direct immersion in the metal oxide or silicate, are immersion in salts of the metals such as sulphates, chlorides, oxalates, formates, lactates or acetates followed by immersion in a hydroxide solution, preferably ammonium hydroxide, or a silicic acid solution, resulting in a gelatinous coating of the metal hydroxide or silicate, the hydroxide being converted to the oxide by heating.  Particular examples are given.ALSO:A silica body in the form of fibre and of at least 90% purity and substantially free of any fluxing ingredient, has a surface coating of at least one compound selected from the group consisting of the silicates, oxides and compounds convertible by heat to oxides of the metals chromium, aluminium, zirconium, titanium, beryllium and magnesium, the coating constituting at least 3% by weight of the coated body.  The fibre is preferably initially of a glass comprising in weight per cent SiO2 52.9; Al2O3 13.8; CaO 21.2; B2O3 9.1; TiO2 0.6; Na2O + K2O 0.5; Fe2O3 0.3; F2 1.4 and traces of Mg O and Mn O.  The fibres may then be woven into a tape or made into paper and the body in the form of fibre, tape or paper leached as by dilute HCl and fired to give a high content of silica. The body is then immersed in the solution or solutions to give the required coating, dried and then heated. Examples other than the direct immersion in the metal oxide or silicate, are immersion in salts of the metals such as sulphates, chlorides, oxalates, formates, lactates or acetates followed by immersion in a hydroxide solution, preferably ammonium hydroxide, or a silicic acid solution, resulting in a gelatinous coating of the metal hydroxide or silicate, the hydroxide being converted to the oxide by heating.  Particular examples are given.  Glass fibre paper is made with silica fibres having a surface crating of at least one compound selected from the group consisting of the silicates, oxides and compounds convertible to oxides by heat of the metals chromium, aluminium, zirconium, titanium, beryllium and magnesium.  In an example, a slurry of silica fibres was pulped into lengths of about 1/100 inch in a 10% by weight solution of chromium sulphate in water and formed into a paper in normal paper-making apparatus.  The paper was then impregnated by pouring over a 50% solution of ammonium hydroxide, giving a highly heat-resistant paper.