The United States of America As Represented by the Administrator of the

The United States of America As Represented by the United States

Domenick E Cagliostro

Ming-ta S Hsu

Timothy S Chen

Salvatore R Riccitiello

Daniel B Leiser

Narcinda R Lerner

Thermal insulation composed of porous ceramic material can be waterproofed by producing a thin silicone film on the surface of the insulation by exposing it to volatile silicone precursors at ambient conditions. When the silicone precursor reactants are multi-functional siloxanes or silanes containing alkenes or alkynes carbon groups higher molecular weight films can be produced. Catalyst are usually required for the silicone precursors to react at room temperature to form the films. The catalyst are particularly useful in the single component system e.g. dimethylethoxysilane (DMES) to accelerate the reaction and decrease the time to waterproof and protect the insulation. In comparison to other methods, the chemical vapor technique assures better control over the quantity and location of the film being deposited on the ceramic insulation to improve the waterproof coating.

Waterproof silicone coatings of thermal insulation and vaporization

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.

Method for waterproofing ceramic materials

Rigid and flexible porous ceramics, including thermal insulation of a type used on space vehicles, are waterproofed by a treatment which comprises applying an aqueous solution of an organopolysiloxane waterproofing agent having reactive silanol groups to the surface of the ceramic and then heating the treated ceramic to form a waterproofed ceramic. The organopolysiloxane is formed by the hydrolysis and partial condensation of di- and trialkoxyfunctional alkylalkoxysilanes having 1-10 carbon atom hydrocarbyl groups.

Organopolysiloxane waterproofing treatment for porous ceramics

The present invention relates to a method for producing ceramic articles and the articles, the process comprising the chemical vapor deposition (CVD) and/or chemical vapor infiltration (CVI) of a honeycomb structure. Specifically the present invention relates to a method for the production of a ceramic honeycomb structure, including:

Ceramic honeycomb structures and method thereof

This invention relates to a method of carbonizing polyacrylonitrile fibers (PAN fibers) by exposing the fibers at an elevated temperature to an oxidizing atmosphere, then exposing the oxidized fibers to an atmosphere of an inert gas such as nitrogen containing a carbonaceous material such as acetylene. The fibers are preferably treated with an organic compound, for example benzoic acid, before the exposure to an oxidizing atmosphere. The invention also relates to the resulting fibers. The treated fibers have enhanced tensile strength.

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Berkeley, CA, United States of America

Domenick E Cagliostro