Transparent, smooth, fracture resistant, discreet, refractory oxide fibers of homogeneous chemical composition comprising 96 to 100 weight percent of a mixture or chemical combination of 67 to 77 parts by weight alumina and 23 to 33 parts by weight silica, said fibers having a predominant polycrystalline phase of mullite, transitional alumina, or a mixture of both, said refractory fibers being made by fiberizing a viscous liquid of oxide precursors comprising a silica sol and a water dispersible alumina sol or water soluble or dispersible organic aluminum salt, and drying, collecting, and calcining the resulting green fibers.
The present invention relates to a ceramic fiber yarn, which has higher weaving and knitting performance. The ceramic fiber yarn comprises a group of filaments, the filaments being made by the steps of spinning mother liquid, which comprises colloidal silica and basic aluminum chloride, and firing, the filaments comprising 67-75 wt % of alumina and 25-33 wt % of silica and mainly having polycrystalline transition alumina, and is characterized in that: the loop strength of each the filament, which is measured by a wire having diameter of 0.5 mm, is at or greater than 2.5.times.10.sup.-2 N (N: Newton); and the crystal structure of the filament substantially changes to polycrystalline mullite after heating for 30 minutes at the temperature of 1,400.degree. C.
A binder system useful in formulating coatings for glass, metal, wood and especially light diffusive coatings for glass light bulb envelopes is disclosed. Excellent coatings can be formed using a binder system comprising dispersible colloidal particles of alumina and finely divided, precipitated silica. When a stable dispersion of these two materials is combined properly with a pigment and/or filler system and then dried upon a glass, metal or wood surface, a tough, continuous, tightly adhering coating is formed. By using the correct pigments, a light diffusive coating for light bulb envelopes can be formed.
The composition for texturing a magnetic disk contains 0.1-5 weight %, based on the composition, of polycrystalline sintered alumina abrasives in a grinding fluid, the abrasives being produced by a sol-gel method comprising the steps of mixing a slurry of alumina hydrate with a dilute acid for solation, mixing the resultant alumina hydrate sol with a seed and/or a modifier, drying said alumina hydrate sol at 50.degree.-120.degree. C. for gelation, pulverizing and classifying the resultant gel, calcinating said gel at 400.degree.-900.degree. C., sintering the calcinated alumina particles at 1100.degree.-1400.degree. C., and pulverizing and classifying the resultant sintered alumina particles to a maximum particle size of 5 .mu.m or less and an average particle size of 0.1-3 .mu.m.
A probe for measuring hydrogen in aluminum melts includes straight inner and outer tubes, the latter having upper and lower plugs and a ceramic fiber sleeve in contact with said upper plug, a straight, ceramic blanketed third tube surrounding said plugs and preventing melt from passing therethrough.
A method for treating the surface of the inner wall of a furnace, said inner wall being lined with ceramic fibers, involves placing a source generating an alkali component in a furnace for firing a material into a product, in which at least the inner wall is lined with a ceramic fiber body, and heating the interior of the furnace to vaporize the alkali component, thereby impregnating the surface layer portion of the ceramic fiber body with the thus vaporized alkali component.
