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AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsDomenick E. Cagliostro, Ming-Ta S. Hsu
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Hygroscopic ceramic materials which are difficult to waterproof with a silane, substituted silane or silazane waterproofing agent, such as an alumina containing, fibrous, flexible and porous, fibrous ceramic insulation used on a reentry space vehicle, are rendered easy to waterproof if the interior, porous surface of the ceramic is first coated with a thin coating of silica. The silica coating is achieved by coating the interior surface of the ceramic with a silica precursor, converting the precursor to silica either in-situ or by oxidative pyrolysis and then applying the waterproofing agent to the silica coated ceramic. The silica precursor comprises almost any suitable silicon containing material such as a silane, silicone, siloxane, silazane and the like applied by solution, vapor deposition and the like. If the waterproofing is removed by, e.g., burning, the silica remains and the ceramic is easily rewaterproofed. An alumina containing TABI insulation which absorbs more that five timed its weight of water, absorbs less than 10 wt. % water after being waterproofed according to the method of the invention.
A method for waterproofing porous ceramic thermal insulation having an exterior and an interior surface which comprises coating said exterior and interior surfaces with a silica precursor, converting said precursor to silica to form a silica coating less than one micron thick, and then coating said silica coated ceramic with a coating of a silicon containing waterproofing agent less than one micron thick.
A flexible waterproofed ceramic composite comprising a porous ceramic blanket insulation fabricated from ceramic fibers, wherein said composite has an exterior surface which is coated with a thin coating of silica less than one micron thick and wherein a thin coating of a silicon containing waterproofing agent less than one micron thick is disposed over said silica coating.
A method for waterproofing porous thermal insulation having an exterior and an interior surface which comprises at least one ceramic material and which is useful for the thermal protection system on a space vehicle, said method comprising coating said exterior and interior surface with a silica precursor, converting said precursor to silica to form a silica coating less than one micron thick, and then coating said silica coated exterior and interior surfaces with a coating less than one micron thick of a silicon containing waterproofing agent.
A method for waterproofing a porous and flexible thermal insulating material having an exterior and an interior surface and comprising at least one material from the group consisting of fabric, batting, fiber and felt made of at least one member from the group consisting of ceramic fiber, thread and filament, said method comprising coating said exterior and interior surfaces with a silica precursor, converting said precursor to silica to form a silica coating less than one micron thick, and then coating said silica coated surfaces with a coating less than one micron thick of a silicon containing waterproofing agent.
A waterproofed, porous and flexible thermal insulating material having an exterior and an interior surface and comprising at least one material from the group consisting of fabric, batting, fiber and felt made of at least one member from the group consisting of ceramic fiber, thread and filament, wherein exterior and interior surfaces are coated with a silica coating less than one micron thick and wherein said silica coated surfaces are coated with a coating less than one micron thick of a silicon containing waterproofing agent.
A material according to claim comprising alumina and which absorbs less than 25 wt. % water after being immersed in water for fifteen minutes.
Dependencies are inferred from the claim text.