Fiber Materials, Inc.

Roger T Pepper

Daniel C Nelson

James R Lennox

Ernest G Kendall

Roy D Marangoni

Paul V Chayka

Douglas S Lewing

Thomas A Zack

Horst Gigerenzer

Layered carbon-carbon composites having improved interlaminar tensile strength are disclosed together with a process for making such composites. A metal catalyst is first deposited on a panel comprising a plurality of layers of carbon fiber cloth. The panel is then exposed to a gaseous hydrocarbon in an inert atmosphere at elevated temperature in order to promote the growth of graphite whiskers between the carbon cloth layers.

Reinforced carbon composites

Monocrystalline ceramic fibers are disclosed together with a process for preparing such fibers. Polycrystalline ceramic fibers in a tow are coated with a coating that is chemically substantially non-reactive with the ceramic (e.g. alumina fibers coated with molybdenum), and the coated fibers are drawn through a heating zone maintained at a temperature high enough to melt the fibers without melting the coating. The coated fibers are withdrawn from the heating zone and cooled rapidly enough to form a substantially monocrystalline ceramic. The protective coating may thereafter be removed to leave a tow of substantially single-crystal ceramic fibers. Monocrystalline ceramic fibers about 8-20 microns in diameter are prepared by the disclosed process.

Monocrystalline ceramic fibers and method of preparing same

A carbonizable body is formed by infusing a plurality of preoxidized (preferably stabilized by known processing to have about 9 to 14 weight percent oxygen) polyacrylonitrile fibers in a polar liquid plasticizer, preferably water, capable of extracting a tarry leachate from the fibers. The infusion of the fibers in the plasticizer is continued for a sufficient time for a substantial amount of leachate to form on the surface of the fibers, and are then consolidated or diffusion-bonded to one another or other fibers, as by orienting the treated fibers in a mold and subjecting them to isostatic pressing at relatively low temperatures and pressure. Further processing of the consolidated fibers with appropriate heat treatment in an inert atmosphere will produce a carbonized bulk product with higher values of Young's modulus for the carbonized material than have been previously achieved at such carbonization temperatures. This carbonaceous product can be truly graphitized by subsequent heat treatment to obtain material with a modulus of at least 40.times.10.sup.6 psi, and a tensile strength of at least 20.times.10.sup.3 psi.

High carbon composite

A carbonizable body is formed by infusing a plurality of preoxidized, preferably stabilized by known processing to have about 9 to 14 weight percent oxygen, polyacrylonitrile fibers in a polar liquid plasticizer, preferably water, capable of extracting a tarry leachate from the fibers. The infusion of the fibers in the plasticizer is continued for a sufficient time for a substantial amount of leachate to form on the surface of the fibers, and are then consolidated or diffusion-bonded to one another or other fibers, as by orienting the treated fibers in a mold and subjecting them to isostatic pressing at relatively low temperatures and pressure. Further processing of the consolidated fibers with appropriate heat treatment in an inert atmosphere will produce a carbonized bulk product with higher values of Young's modulus for the carbonized material than have been previously achieved at such carbonization temperatures. This carbonaceous product can be truly graphitized by subsequent heat treatment to obtain material with a modulus of at least 40.times.10.sup.6 psi, and a tensile strength of at least 20.times.10.sup.3 psi.

Method of making a structure

A carbonizable body is formed by infusing a plurality of preoxidized, preferably stabilized by known processing to have about 17 to 30 weight percent oxygen, fibers prepared from pitch, in a non-polar liquid plasticizer, typically quinoline, capable of extracting a tarry leachate from the fibers. The infusion of the fibers in the plasticizer is continued for a sufficient time for a substantial amount of leachate to form on the surface of the fibers. The treated fibers are then consolidated or diffusion-bonded to one another or other fibers, as by orienting the treated fibers in a mold and subjecting them to isostatic pressing at relatively low temperatures and pressure. Further processing of the consolidated fibers with appropriate heat treatment in an inert atmosphere will produce a carbonized bulk product with higher values of Young's modulus for the carbonized material than have been previously achieved at such carbonization temperatures. This carbonaceous product can be truly graphitized by subsequent heat treatment to obtain material with a modulus of at least 40.times.10.sup.6 psi, and a tensile strength of at least 20.times.10.sup.3 psi.

Method of making a structure from carbonaceous fibers

A novel process is provided for the formation of improved carbonized fibrous materials with increased modulus of elasticity and strength as well as decreased diameter. Preferably, the precursor material is acrylonitrile, typically copolymerized with a minor amount of an acrylic monomer such as methyl acrylate. Drawing of the polymer fiber during oxidation is effected at an elevated temperature in the presence of a carboxylic acid (other than formic acid), or its anhydride, within the fiber. It is believed that the acid and/or its anhydride which is formed at the oxidizing temperature serves as a plasticizer and reduces the fiber yield stress and increases fiber plasticity so that the fibers may be drawn by as much as 300% or more in the presence of the acid and/or its anhydride during oxidation, thereby providing the desired improvement in increased modulus of elasticity and tensile strength of carbon fibers formed subsequently by carbonization of the oxidized fibers.

Method of producing carbon fiber and product thereof

An acoustical insulating material comprises a fiber reinforced lead composite sheet or panel. In a preferred embodiment of the invention the fibers are substantially axially parallel aligned with one another. The frequency absorption and transmission characteristics of the material may be varied by mechanically stressing the material, e.g. as by placing the material under tension in the direction of fiber orientation.

Acoustic filter

A carbon fiber reinforced metal matrix composite is produced by depositing a metal boride coating on the surface of the fibers and subsequently immersing the fibers in a molten bath of the metal matrix material. The boride coating is formed by passing carbon fiber through a gaseous mixture of chlorides of the metal and boron in the presence of zinc vapor at elevated temperatures. The subsequent reaction deposits out a submicron lamina of metal boride on the carbon fibers serving to enhance wetting of the fibers by the molten metal, with the lamina preventing chemical reaction between the fibers and metal matrix materials and also providing a strong mechanical bond therebetween.

Reinforced metal matrix composite

A novel graphite fiber/metal composite material in which the graphite fibers have an adherent coating of silicon oxide and silicon carbide. The coating protects the graphite surface from attack by carbide forming matrix metals such as aluminum, titanium, magnesium and nickel. In a preferred embodiment of the invention the coating is formed by an intermediate temperature vapor deposition technique involving the reduction of silicon tetrachloride in the presence of hydrogen and an oxygen containing gas.

Growing community of inventors

Scarborough, ME, United States of America

Roger T Pepper