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

Other

The United States of America As Represented by the United States

Salvatore R Riccitiello

Ming-ta S Hsu

Timothy S Chen

Paul M Sawko

Daniel J Rasky

Huy K Tran

William D Henline

James C Fletcher

Robert A Frosch

Edward S Harrison

Charles L Hamermesh

Howard E Goldstein

Marnell Smith

Domenick E Cagliostro

Ming-Ta Hsu

Chadwick B Delano

Carlos A Estrella

Norman B Zimmerman

A low-density resin impregnated ceramic article advantageously employed as a structural ceramic ablator comprising a matrix of ceramic fibers. The fibers of the ceramic matrix are coated with an organic resin film. The organic resin can be a thermoplastic resin or a cured thermosetting resin. In one embodiment, the resin is uniformly distributed within the ceramic article. In a second embodiment, the resin is distributed so as to provide a density gradient along at least one direction of the ceramic article. The resin impregnated ceramic article is prepared by providing a matrix of ceramic fibers; immersing the matrix of ceramic fibers in a solution of a solvent and an organic resin infiltrant; and removing the solvent to form a resin film on the ceramic fibers.

Low-density resin impregnated ceramic article and method for making the

A low-density resin impregnated ceramic article advantageously employed as a structural ceramic ablator comprising a fired preform of ceramic fibers. The fibers of the ceramic preform are coated with an organic resin film. The organic resin can be a thermoplastic resin or a cured thermosetting resin. In one embodiment, the resin is uniformly distributed within the ceramic article. In a second embodiment, the resin is distributed so as to provide a density gradient along at least one direction of the ceramic article. The resin impregnated ceramic article is prepared by providing a fired preform of ceramic fibers; immersing the preform of ceramic fibers in a solution of a solvent and an organic resin infiltrant; and removing the solvent to form a resin film on the ceramic fibers.

Low-density resin impregnated ceramic article having an average density

The present invention concerns novel high strength ceramic fibers derived from boron, silicon, and carbon organic precursor polymers. The ceramic fibers are thermally stable at and above 1200.degree. C. in air. The method for preparation of the boron-silicon-carbon fibers from a low oxygen content organosilicon boron precursor polymers of the general formula Si(R.sub.2)BR.sup.1 by melt-spinning, crosslinking and pyrolysis. Specifically, the crosslinked (or cured) precursor organic polymer fibers do not melt or deform during pyrolysis to form the silicon-boron-carbon ceramic fiber. These novel silicon-boron-carbon ceramic fibers are useful in high temperature applications because they retain tensile and other properties up to 1200.degree. C., from 1200.degree. to 1300.degree. C., and in some cases higher than 1300.degree. C.

Ceramic silicon-boron-carhon fibers from organic silicon-boron-polymers

The present invention relates to a process for the production of an organoborosilicon preceramic polymer of the structure: ##STR1## wherein R.sup.1 is selected from alkyl having from 1 to 10 carbon atoms or phenyl, and x is selected from 0, 1, 2 or 3;

Boron-carbon-silicon polymers and ceramic and a process for the

Boron-carbon-silicon polymers and the ceramic thereof

The present invention relates to a polyorganoborosilane ceramic precursor polymer comprising a plurality of repeating units of the formula: ##STR1## with the segments being linked together by second units of the formula: --[(R.sup.2)--Si--R.sup.3)--q, where R.sup.1 is lower alkyl, cycloalkyl, phenyl, or ##STR2## and R.sup.2 and R.sup.3 are each independently selected from hydrogen, lower alkyl, vinyl, cycloalkyl, or aryl, n is an integer between 1 and 100; p is an integer between 1 and 100; and q is an integer between 1 and 100. These materials are prepared by combining an organoborohalide of the formula R.sup.4 --B--(X.sup.1).sub.2 where R.sup.4 is selected from halogen, lower alkyl, cycloalkyl, or aryl, and an organohalosilane of the formula: R.sup.2 (R.sup.3) Si(X.sup.2).sub.2 where R.sup.2 and R.sup.3 are each independently selected from lower alkyl, cycloalkyl, or aryl, and X.sup.1 and X.sup.2 are each independently selected from halogen, in an anhydrous aprotic solvent having a boiling point at ambient pressure of not greater than 160.degree. C. with in excess of four equivalents of an alkali metal, heating the reaction mixture and recovering the polyorganoborosilane. These silicon boron polymers are useful to generate high-temperature ceramic materials, such as SiC, SiB.sub.4, and B.sub.4 C, upon thermal degradation above 600.degree. C.

Boron-containing organosilane polymers and ceramic materials thereof

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

The present invention relates to a polyorganoborosilane ceramic precursor polymer comprising a plurality of repeating units of the formula: ##STR1## with the segments being linked together by second units of the formula: --(R.sup.2)--Si--R.sup.3)--q, where R.sup.1 is lower alkyl, cycloalkyl, phenyl, or ##STR2## and R.sup.2 and R.sup.3 are each independently selected from hydrogen, lower alkyl, vinyl, cycloalkyl, or aryl, n is an integer between 1 and 100; p is an integer between 1 and 100; and q is an integer between 1 and 100. These materials are prepared by combining an organoborohalide of the formula R.sup.4 -B-(X.sup.1).sub.2 where R.sup.4 is selected from halogen, lower alkyl, cycloalkyl, or aryl, and an organohalosilane of the formula : R.sup.2 (R.sup.3) Si(X.sup.2).sub.2 where R.sup.2 and R.sup.3 are each independently selected from lower alkyl, cycloalkyl, or aryl, and X.sup.1 and X.sup.2 are each independently selected from halogen, in an anhydrous aprotic solvent having a boiling point at ambient pressure of not greater than 160.degree. C. with in excess of four equivalents of an alkali metal, heating the reaction mixture and recovering the polyorganoborosilane. These silicon boron polymers are useful to generate high-temperature ceramic materials, such as SiC, SiB.sub.4, and B.sub.4 C, upon thermal degradation above 600.degree. C.

The present invention discloses a ceramic reusable externally applied thermal protection system (TPS). The system functions by using the composite device created by combining an upper shell, thermal insulation and lower tile components shown in FIG. 2. The upper shell effectively separates its primary functions as a toughened outer-surface and load carrier. In a preferred embodiment, a structurally strong ceramic/ceramic upper shell is manufactured from ceramic cloth upon which additional ceramic material has been deposited and maintains the configuration of the upper shell. The lower tile is composed of lightweight ceramic normally acceptable in this application. One or more lightweight rigid or flexible insulation materials are used in the cavity created by combining the upper shell and lower tile. The assembly of the overall tile is facilitated by attachment means effective to withstand the temperature and stress conditions. These attachment means include a self-locking wedge and complementary surface, ceramic pins, augers and the like. The device is useful on the interior surface of a kiln or the like and is also attached to the exterior surface of an aerospace vehicle for thermal protection.

Ceramic/ceramic shell tile thermal protection system and method thereof

The present invention relates to a method of preparing B-trichloroborazine, B.sub.3 N.sub.3 Cl.sub.3 H.sub.3. Generally, the method includes the combination of gaseous boron trichloride in an anhydrous aprotic organic solvent followed by addition of excess gaseous ammonia at ambient temperature or below. The reaction mixture is heated to between about 100.degree. to 140.degree. C. followed by cooling, removal of the solid ammonium chloride at ambient temperature, distillation of the solvent under vacuum if necessary at a temperature of up to about 112.degree. C., and recovery of the B-trichloroborazine. Solvents include, toluene, benzene, xylene, chlorinated hydrocarbons, chlorinated aromatic compounds, or mixtures thereof. Toluene is a preferred solvent. The process provides a convenient synthesis of a material which often decomposes on standing. B-trichloroborazine is useful in a number of chemical reactions, and particularly in the formation of high temperature inorganic polymers and polymer precursors.

Preparation of B-trichloroborazine

Flame and temperature resistant polyimide foams are prepared by the reaction of an aromatic dianhydride, e.g., pyromellitic dianhydride, with an aromatic polyisocyanate, e.g., polymethylene polyphenylisocyanate (PAPI) in the presence of an inorganic acid and a lower molecular weight alcohol, e.g., dilute sulfuric acid or phosphoric acid and furfuryl alcohol. The exothermic reaction between the acid and the alcohol provides the heat necessary for the other reactants to polymerize without the application of any external heat. Such mixtures, therefore, are ideally suited for in situ foam formation, especially where the application of heat is not practical or possible.

Ambient cure polyimide foams prepared from aromatic polyisocyanates,

Polyimide foam products having greatly improved burn-through and flame-spread resistance are prepared by the reaction of aromatic polyisocyanates with aromatic dianhydrides in the presence of metallic salts of octoic acid. The salts, for example stannous octoate, ferric octoate and aluminum octoate, favor the formation of imide linkages at the expense of other possible reactions.

Catalysts for polyimide foams from aromatic isocyanates and aromatic

New, flexible intumescent protection sheeting of unusually uniform thickness have been prepared from epoxy-polysulfide compositions containing microfibers and the ammonium salt of 1,4-nitroaniline-2-sulfonic acid, as disclosed in U.S. Pat. No. 3,663,464, except that an ammonium salt particle size in the order of 5 to 8 microns and a fiber size of about 1/128th inch in length and 3 to 5 microns in diameter have been found critical to obtain the required density of 1.46 to 1.50 g/cc. The insulation sheeting is prepared by a continuous process involving vacuum mixing, calendering, and curing under very strict conditions which depend to some extent upon the thickness of the sheet produced. The resulting flexible sheet can be wrapped easily and tightly around small diameter missiles, thus affording them for the first time, protection from fire for at least 5 minutes. The material is also suited for the protection of other articles with convoluted or contoured surfaces, which require covering of highly uniform thickness.

Fire protection covering for small diameter missiles

Foamed cross-linked poly-N-arylenebinzimidazoles are prepared by mixing an organic tetraamine and an ortho substituted aromatic dicarboxylic acid anhydride in the presence of a blowing agent and then heating the prepolymer to a temperature sufficient to complete polymerization and foaming of the reactants. In another embodiment of the process, the reactants are heated to form a prepolymer. The prepolymer is then cured at higher temperatures to complete foaming and polymerization.

Polymeric foams from cross-linkable poly-N-ary lenebenzimidazoles

An intumescent-ablator coating composition which comprises an intumescent agent such as the ammonium salt of 1,4-nitroaniline-2-sulfonic acid or 4,4-dinitrosulfanilide, a polymeric binder system and about 5 to 30% by weight, based on the total weight of the intumescent agent and the binder, of an endothermic filler having a decomposition temperature about or within the exothermic region of the intumescent agent.

Growing community of inventors

San Jose, CA, United States of America

Salvatore R Riccitiello