Abstract: Controlled buoyancy of underwater pipe installations, typically subsea risers, is achieved by securing to the pipe at least two buoyancy members each comprising a plurality of rigid hollow tubular members arranged side-by-side to form a group which is enclosed in a rigid liquid-tight shell. Advantageously, the tubular members have flat sides lying in planes which are radial with respect to the pipe when the buoyancy member is in place, and adjacent pairs of the tubular members are in flush side-wall-to-side-wall contact. Superior results are obtained when the tubular members are pultrusions of polymeric material and the shells are continuous layers of fiber-filled polymeric material.

Abstract: Fibrous carbon material such as graphite cloth which is to be combined with a thermosetting resin and a boron containing compound to form a carbon-carbon composite is provided with a protective coating consisting of cured furfuryl alcohol copolymers. When formed into a laminate and heated to at least 2150.degree. C. to carbonize and at least partially graphitize the thermosetting resin, the boron greatly increases the interlaminar tensile strength while the coating protects the fibrous material from adverse effects of the boron which reduce the tensile strength in the directions of the fibers of the fibrous carbon material of the composite.

Abstract: A finish composition for fibrous material such as carbon, graphite or silica fibers comprises an aqueous emulsion of an elastomer and a lubricious substance which are both dispersed in the aqueous emulsion. The elastomer comprises a latex of butyl rubber or butadiene/nitrile type rubbers, and the lubricious substance comprises an emulsion of a hydrocarbon type wax such as paraffin. The aqueous emulsion which includes a dispersant such as water proportioned to provide the emulsion with a solids concentration of up to about 1% is applied as a size to the fibrous material, following which the water is driven off such as by use of elevated temperatures to cause the lubricious substance to separate from the elastomer and exude to the surface of the elastomeric sheath surrounding the fibrous material. The finish may be used as an aid to weaving, in which event it is applied to fibers such as carbon or graphite fibers prior to weaving and then removed after the weaving is completed.

Abstract: A high-strength, low weight, electromechanical cable is manufactured from aromatic polyamide multifilament yarns impregnated with a hydrolytically stable polyurethane resin to form a protective coating. The coating provides load adjustment from fiber to fiber, eliminates abrasive self-destruction of the fibers during flexing of the yarn under load, protects the fiber to some extent from ultraviolet radiation, aggressive chemicals or abrasive particles and makes it possible to preform the yarn. The coating comprises a reaction product of a liquid tetramethylene glycol, an aliphatic/cycloaliphatic diisocyanate and a diamine coupling-curing agent. The impregnated yarns are dried, twisted together, heated above the softening point of the resin to fuse the coatings of adjacent yarns, and then cooled to form a set twisted helix of the yarns.

Abstract: In a metal reheating furnace, a resilient, vibration resistant and easily installed thermal insulative structure is defined by an inner batt of refractory fibers held in place by an outer wrapping of woven refractory fibers and so arranged as to be self-retaining. This relatively soft, resilient structure supports an outer shell of refractory mortar which adheres to but does not substantially penetrate the woven wrapping, such that vibration and mechanical shock are absorbed in the soft insulation while the exterior layer protects against molten slag and high speed impinging gas flows.

Abstract: There are disclosed furfuryl alcohol copolymers of a polyester prepolymer of maleic acid or anhydride and a polyhydric alcohol which incorporate tungsten and/or molybdenum metal atoms. The metal atoms are incorporated into the copolymers by reacting the polyester prepolymer with a reaction product of tungsten or molybdenum and pyrrolidine.

Abstract: An underwater panel comprises a three-dimensional structure for housing sound absorbing material therein, the structure being waterproof and extremely rigid in construction to prevent compression of the sound absorbing material in an environment of relatively high water pressure while at the same time being relatively highly sound transmissive so as to readily pass energy waves from the surrounding water into the sound absorbing material. The panel comprises an integrally woven and resin impregnated fabric which is relatively highly sound transmissive and which has a pair of waterproof opposite faces joined by a pair of intermediate ribs. A plurality of generally planar stiffening elements which are highly sound transmissive and which may be made from resin impregnated fabrics are inserted into the fabric so as to extend between the opposite faces and provide substantial resistance to compression of the panel due to the pressure of the surrounding water.

Abstract: Buoyancy members in the form of a segment of a hollow cylinder are produced by providing a cylindrical mold having two longitudinally extending flanges spaced apart by not more than 180.degree.

Abstract: A low toxicity, castable, fast curing, polyurethane high strength elastomer is prepared from a liquid prepolymer diol, a cycloaliphatic diisocyanate, a polyalkanol amine and a small amount of soluble metal salt catalyst. The composition can be formulated by either a prepolymer or "one-shot" technique and cures at ambient temperature.

Abstract: A high-strength, low weight, electromechanical cable is disclosed. The cable is formed by polyamide multifilaments impregnated with a hydrolytically stable polyurethane to form a protective coating. The coating provides load adjustment from fiber to fiber, eliminates abrasive self-destruction of the fibers during flexing of the yarn under load, protects the fiber to some extent from ultraviolet radiation, aggressive chemicals or abrasive particles and makes it possible to preform the yarn. The coating comprises a reaction product of a liquid tetramethylene glycol, an aliphatic/cycloaliphatic diisocyanate and a diamine coupling-curing agent. The impregnated fibers are dried, twisted and then heated to the melting temperature of the coating.

Abstract: Readily installable, highly efficient insulating structures for affixation to bodies requiring insulation comprise successive sheets of closely spaced heat resistive metal foil configured to maintain the intersheet spacing under the stress of gravity and other external forces. Each sheet of foil includes a plurality of corrugations which extend through part but not all of the gaps between adjacent sheets to minimize convection, and which in one embodiment abut corrugations of adjacent sheets to maintain the intersheet spacing. In one embodiment the corrugations are V-shaped in cross section and extend along the length of the sheet on one side thereof.

Abstract: A laminated article of hollow, circular shape includes an outer layer of relatively hard and strong carbonaceous material, an intermediate layer of highly deformable carbonaceous material disposed within the outer layer, and an inner layer of pyrolytic graphite deposited on the inner surface of the intermediate layer. The intermediate layer undergoes substantial compresssion with some permanent compaction thereof as the article cools following deposition of the pyrolytic graphite, due to the much greater shrinkage of the outer layer as compared with the layer of pyrolytic graphite. At the same time the intermediate layer has a desired amount of elasticity so as to exert nominal compressive stress on the layer of pyrolytic graphite. The intermediate layer may be comprised of porous carbon, and may have a surface thereof made very smooth in preparation for receipt of the pyrolytic graphite by infiltration, seal coating or other techniques.

Abstract: At least partially carbonized fibers formed by pyrolysis from precursor fibers are converted to graphitic fibers in successive heating and stretching zones in which a transitional phase of high fiber reactivity is utilized. Chemical agents applied to the fibers during this transition increase matrix-fiber adhesion properties by reacting with the fibers before they develop excessive levels of crystallographic order and become inert at graphitization temperature levels. Improved control of fiber properties is achieved by employment of short residence times and resistive heating with concurrent stretching in the zones, and by imparting high stretch levels at relatively low temperatures to the fibers. The resultant fibers have superior properties for component structures and at the same time have excellent tenacity and modulus values as well.

Abstract: A multi-ply woven article has elements positioned within pockets formed by double plies of the article to provide the article with desirable acoustical properties as well as considerable strength and rigidity. The double plies may comprise a generally parallel pair of rib plies which extend between the opposite faces of the article in generally zig zag fashion to form a plurality of intermediate rib portions, or a pair of generally parallel, spaced apart face plies forming each of the opposite faces of the article, or both. Some of the pockets formed by the double plies are filled with acoustical elements having a selected number of holes of appropriate size so as to pass sound waves therethrough at a controlled rate, while still other pockets are filled with non-acoustical elements which are generally impervious to sound waves.

Abstract: A multi-ply woven article has stiffening elements positioned within pockets formed by double plies of the article to provide the article with substantial strength and rigidity. The double plies may comprise a generally parallel pair of rib plies which extend between the opposite faces of the article in generally zig zag fashion to form a plurality of intermediate rib portions, or a pair of generally parallel, spaced apart face plies forming each of the opposite faces of the article, or both. The various stiffening elements may comprise one or more layers of relatively stiff material. The various layers comprising each stiffening element may comprise unidirectional fibers or materials oriented relative to the woven article so as to impart maximum strength in selected directions.

Abstract: Acoustical panels are comprised of woven fabrics which have at least one face ply portion woven of warp and fill yarns comprising yarns of non-fugitive and fugitive material. The fabric is woven relatively densely to facilitate handling and use thereof in fabrication of the acoustical panel. The substantial disintegration of the fugitive strands of yarn at the completion of the fabrication process provides a selected porosity in the face portion of the woven fabric for controlled transmission of sound waves into the interior of the panel.In a preferred method of making an acoustical panel, the fabric is woven of yarns comprising a mixture of non-fugitive and fugitive material. After installation of porous acoustical elements into pockets formed in the face portion and insertion of mandrels into flutes formed within the fabric, the fabric is impregnated with resin, cured, and the mandrels removed.

Abstract: A coherent, adherent, thin coating for metal surfaces is disclosed. The coating comprises a polymeric composition of a high vinyl content, liquid, hydroxy-terminated butadiene prepolymer, chain extended and cured by polyisocyanates and polyamines. The coating is sprayed onto an aluminum surface and after evaporation of solvent and curing for a short period at elevated temperature exhibits an adhesion to aluminum of between 0.2 lb/in to 2 lb/in, an elongation of 75% to 150%, and a tensile strength from 1,000 to 4,000 psi. The coating is strippable when applied at 2-5 mil thickness onto aluminum, and protects the metal surface during etching in chromic acid, during high temperature bonding and during final assembly operations. The coated surfaces can be machined, riveted, drilled and stretch formed without any lifting or tearing of the coating.

Abstract: The transverse properties of high modulus fabric such as graphite are significantly improved by continuously processing the material through a multiple roller unit under warp tension while restraining fill shrinkage by wrapping the material no less than 180.degree. around each roll and by minimizing unrestrained inter-roll travel by controlling the inter-roll span. Graphite precursor fabrics such as polyacrylonitrile (PAN) can be stretched as high as 45% in the warp direction with as little as 1-2% shrinkage in the fill direction. The invention also relates to simultaneous stretching and preoxidation of the precursor fabric under tension and while minimizing fill shrinkage.

Abstract: A multi-ply woven fabric article as disclosed has opposite woven face plies and a pair of woven rib plies which extend alternately between and are interwoven with the face plies. The rib plies which are interwoven with each other at the regions of interweaving with the face plies form parallel pairs of ribs extending between the opposite face plies in zig zag fashion and defining generally planar pockets therebetween. The pockets so formed are capable of readily receiving generally planar stiffening elements to provide a woven fabric article of substantial compressive strength.