Abstract: A method of manufacturing a coated reinforcing fiber for use in Ceramic Matrix Composites, the method comprising pre-oxidizing a plurality of silicon-based fibers selected from the group consisting of silicon carbide (SiC) fibers, silicon nitride (Si3N4) fibers, SiCO fibers, SiCN fibers, SiCNO fibers, and SiBCN fibers at between 700 to 1300 degrees Celsius in an oxidizing atmosphere to form a silica surface layer on the plurality of silicon-based fibers, forming a plurality of pre-oxidized fibers; applying a rare earth orthophosphate (REPO4) coating to the plurality of pre-oxidized fibers; and heating the plurality of REPO4 coated pre-oxidized fibers at about 1000-1500 degrees Celsius in an inert atmosphere to react the REPO4 with the silica surface layer to form a rare earth silicate or disilicate. The pre-oxidizing step may be 0.5 hours to about 100 hours. The heating step may be about 5 minutes to about 100 hours.

Abstract: A method of manufacturing a coated reinforcing fiber for use in Ceramic Matrix Composites, the method comprising pre-oxidizing a plurality of silicon-based fibers selected from the group consisting of silicon carbide (SiC) fibers, silicon nitride (Si3N4) fibers, SiCO fibers, SiCN fibers, SiCNO fibers, and SiBCN fibers at between 700 to 1300 degrees Celsius in an oxidizing atmosphere to form a silica surface layer on the plurality of silicon-based fibers, forming a plurality of pre-oxidized fibers; applying a rare earth orthophosphate (REPO4) coating to the plurality of pre-oxidized fibers; and heating the plurality of REPO4 coated pre-oxidized fibers at about 1000-1500 degrees Celsius in an inert atmosphere to react the REPO4 with the silica surface layer to form a rare earth silicate or disilicate. The pre-oxidizing step may be 0.5 hours to about 100 hours. The heating step may be about 5 minutes to about 100 hours.

Abstract: An improved method for coating ceramic fibers and woven cloths of ceramic fibers is disclosed, wherein the ceramic fibers are thoroughly wetted with precursors in a solution before the precursors react to form a coating by heterogeneous nucleation and growth. The fibers are then rinsed and fired and, where desired, the process may be repeated in stages to increase the coating thickness as desired. This method is amenable to operation in both the batch and continuous modes. This flexible method reduces both the cost and time of producing ceramic matrix composites (CMCs).

Abstract: A carbon-rich zirconia-silica sol is prepared by the steps of dissolving zirconyl nitrate hydrate in absolute ethanol, mixing the solution thus obtained with a silicon alkoxide, and mixing the latter solution with a polyelectrolyte. The resulting carbon-rich sol/polyelectrolyte mixture can be employed to coat continuous fiber tow or filaments, to make nanosized zircon powder and to make a porous zircon membrane material.

Abstract: An improved method for producing a fiber-reinforced ceramic composite having a monazite interface between the reinforcing fiber and the ceramic matrix, which comprises the steps of coating each filament in a continuous fiber tow with an aqueous sol that forms monazite after high temperature heat treatment, heat treating the thus-coated fiber tow to provide a coated tow having a layer of monazite thereon, embedding the fiber in a suitable ceramic matrix, and densifying the composite.