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Riccitiello, S. R.

Publications and source records attributed to Riccitiello, S. R..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Chemical-Vapor Deposition Of Silicon Carbide

Report describes experiments in chemical-vapor deposition of silicon carbide by pyrolysis of dimethyldichlorosilane in hydrogen and argon carrier gases. Directed toward understanding chemical-kinetic and mass-transport phenomena affecting infiltration of reactants into, and deposition of SiC upon, fabrics. Part of continuing effort to develop method of efficient and more nearly uniform deposition of silicon carbide matrix throughout fabric piles to make improved fabric/SiC-matrix composite materials.

Cagliostro, D. E.↗
NASA NTRS1993

Ceramic fibers from Si-B-C polymer precursors

Non-oxide ceramics such as silicon carbide (SiC), silicon nitride (Si3N4), and silicon borides (SiB4, SiB6) have thermal stability, oxidation resistance, hardness, and varied electrical properties. All these materials can be prepared in a fiber form from a suitable polymer precursor. The above mentioned fibers, when tested over a temperature range from 25 to 1400 C, experience degradation at elevated temperatures. Past work in ceramic materials has shown that the strength of ceramics containing both carbides and borides is sustained at elevated temperatures, with minimum oxidation. The work presented here describes the formation of ceramic fibers containing both elements, boron and silicon, prepared via the polymer precursor route previously reported by the authors, and discusses the fiber mechanical properties that are retained over the temperature range studied.

Riccitiello, S. R.↗
NASA NTRS1990

Pyrolysis Products Of Dimethyldichlorosilane

Report describes experimental study of chemical reactions and chemical products of chemical-vapor deposition of silicon carbide from dimethyldichlorosilane. Topic important because it relates to current interest in lightweight refractory materials for use in advanced aircraft and spacecraft. Analyses showed that at temperature of 700 to 1,100 degrees C and contact time of about 1 minute, SiC forms by two chemical-reaction paths.

Cagliostro, D. E.↗
NASA NTRS1988

Ceramic Fabric Coated With Silicon Carbide

Material used as high-temperature shell. Ceramic fabric coated with silicon carbide (SiC) serves as tough, heat-resistant covering for other refractory materials. Developed to protect reusable insulating tiles on advanced space transportation systems. New covering makes protective glaze unnecessary. Used on furnace bricks or on insulation for engines.

Riccitiello, S. R.↗
NASA NTRS1984

Advanced leading edge thermal-structure concept. Direct bond reusable surface insulation to a composite structure

An advanced leading-edge concept was analyzed using the space shuttle leading edge system as a reference model. The comparison indicates that a direct-bond system utilizing a high temperature (2700 F) fibrous refractory composite insulation tile bonded to a high temperature (PI/graphite) composite structure can result in a weight savings of up to 800 lb. The concern that tile damage or loss during ascent would result in adverse entry aerodynamics if a leading edge tile system were used is addressed. It was found from experiment that missing tiles (as many as 22) on the leading edge would not significantly affect the basic force-and-moment aerodynamic coefficients. Additionally, this concept affords a degree of redundancy to a thermal protection system in that the base structure (being a composite material) ablates and neither melts nor burns through when subjected to entry heating in the event tiles are actually lost or damaged during ascent.

Riccitiello, S. R.↗
NASA NTRS1980

Self-curing polyimide foam

Chemical formulation produces foamed polyimide plastic without externalheat. Foam is less dense and more flame and acid resistant than conventional polyimide foams. Self curing foam can be formed "onsite" in limitedaccess locations where application of heat is difficult or impossible.

Riccitiello, S. R.↗
NASA NTRS1979

Catalysts for polyimide foams from aromatic isocyanates and aromatic dianhydrides

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.

Riccitiello, S. R.↗
NASA NTRS1979

Wear, friction, and temperature characteristics of an aircraft tire undergoing braking and cornering

An investigation to evaluate the wear, friction, and temperature characteristics of aircraft tire treads fabricated from different elastomers is presented. The braking and cornering tests performed on aircraft tires retreaded with currently employed and experimental elastomers are described. The tread wear rate is discussed in relation to the slip ratio during braking and yaw angle during cornering. The extent of wear in either operational mode is examined in relation to the runway surface.

Mccarty, J. L.↗
NASA NTRS1979

Fire protection covering for small diameter missiles

Flexible intumescent protection sheeting of unusually uniform thickness were 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 were found critical to obtain the required density of 1.46 to 1.50 g/cc. The insulation sheeting was 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.

Riccitiello, S. R.↗
NASA NTRS1979

Improved imide polymerization catalyst

Catalyzation of imide polymers with metallic salts of 2-ethyl hexanoic acid allows reaction in production of flame resistant foams to proceed in one step without formation of undesirable heat-sensitive byproducts.

Estrella, C. A.↗
NASA NTRS1979

Fire-retardant covering for small containers

Flexible intumescent sheets of exceptionally uniform thickness may be used to protect containers and other small objects less than 25.4 cm in diameter from fire hazards.

Riccitiello, S. R.↗
NASA NTRS1979

Ambient curing fire resistant foams

The feasibility of development of an ambient curing foam is described. The thermal stability and flame spread index of the foams were found to be comparable to those of the high-temperature cured polyimide foams by Monsanto two-foot tunnel test and NASA T-3 Fire test. Adaptation of the material to spray in place applications is described

Hamermesh, C. L.↗
NASA NTRS1978

Ambient cure polyimide foams

Flame and temperature resistant polyimide foams are prepared by the reaction of an aromatic dianhydride, (pyromellitic dianhydride) with an aromatic polyisocyanate, (polymethylene polyphenylisocyanate), in the presence of an inorganic acid and furfuryl alcohol. Usable acids include dilute sulfuric acid, dilute nitric acid, hydrochloric acid, polyphosphoric acid, and phosphoric acid, with the latter being preferred. The dianhydride and the isocyanate in about equimolar proportions constitute about 50% of the reaction mixture, the rest being made up with the acid and the alcohol in a ratio of about 1:10. An exothermic reaction between the acid and the alcohol provides the heat necessary for the other components to polymerize without recourse to external heat sources. The mixture can be sprayed on any surface to form polymeric foam in locations where the application of heat is not practical or possible, for instance, between walls or on mine tunnel surfaces.

Sawko, P. M.↗
NASA NTRS1978

Intumescent-ablator coatings using endothermic fillers

An intumescent-ablator coating composition which contains the ammonium salt of 1,4-nitroaniline-2-sulfonic acid or 4,4 dinitrosul fanilide, a polymeric binder system and about 5 to 30% weight of an endothermic filler is reported. The filler has a decomposition temperature about or within the exothermic region of the intumescent agent.

Sawko, P. M.↗
NASA NTRS1977

Intumescent coatings containing 4,4'-dinitrosulfanilide

A coating which is stable to the environment and to exposure to water, and which intumesces at a favorable temperature was developed. The composition comprises a mixture of 4, 4 prime dinitrousulfanilide as the intumescent agent in a polymer binder mixture of a chlorinated polyolefin, a bisphenol A epoxy resin, and a rubber-like amine hardener.

Sawko, P. M.↗
NASA NTRS1977

Improved intumescent coating

Fire-retardant intumescent coating has increased environmental stability and improved insulative characteristics.

Sawko, P. M.↗
NASA NTRS1977

Intumescent-ablators as improved thermal protection materials

Nitroaromatic amine-based intumescent coatings were improved with regard to their thermal protection ability by adding endothermic decomposing fillers with endotherms at or near the exothermic reaction of the intumescent agent, since the effectiveness of the intumescent coatings without fillers is reduced by the exothermic behavior of the coatings during thermal activation. Fillers were dispersed directly in the base coating. Potassium fluoborate, ammonium fluoborate, zinc borate, and ammonium oxalate function as endothermic ablative materials at specific temperature regions, and also enhance the char formation during the intumescent process.

Sawko, P. M.↗