Dimensionally stable high surface area anode comprising graphitic carbon fibers

The surface of a carbon fiber is treated to improve the strength of its bond with a matrix. The fiber is made an anode by connecting it electrically with the anode current input terminal of an electrolytic treatment bath containing an electrolyte and having a cathode. The fiber is subjected to electrolysis in the bath. The relative distance between the fiber and the cathode in the bath decreases as the distance from the anode current input terminal along the fiber is increased.

Carbon fiber surface treatment

An ultrahigh strength carbon fiber having a surface layer having a crystalline completeness which is substantially the same as or higher than that of the central region of the fiber, and a functional group amount ratio (Ols /Cls) of 0.1 to 0.4 as detected in the fiber surface by X-ray photoelectron spectroscopy, the surface layer preferably having an ultrathin outermost layer having a lower crystalline completeness than the central region of the fiber.

Ultrahigh strength carbon fibers

Yarns or tows of high strength composite fibers the majority of which comprise a core of carbon or the like and a thin, uniform firmly adherent electrically conductive layer or an electrodepositable metal, such as nickel or the like, the bond strength of the metal to the core being greater than 10 percent of the intermetallic bond strength of the metal layer. The composites can be produced by electrodeposition from a bath onto the core but the procedure must use external voltages high enough both (i) to dissociate the metal at the core and (ii) to nucleate the metal through the boundary layer into direct contact with the core.

Apparatus for the production of continuous yarns or tows comprising high strength metal coated fibers

A method of electrochemically surface-treating carbon fibers, fibers treated by the method, and composite materials including such fibers. The method consists in positively polarizing fibers relative to a cathode in an aqueous solution of an electrolyte constituted by a weak amino base. Nitrogen-containing groups are thus fixed to the surface of the fibers thereby improving the adhesion of the fibers to the resin in a composite material constituted by carbon fibers embedded in a synthetic resin matrix.

Method of electrochemically surface treating carbon fibers, fibers treated by the method, and composite materials including such fibers

An improved electrolytic process is provided for modifying the surface characteristics of an electrically conductive high modulus graphitic carbonaceous fibrous material (i.e., exhibiting a mean single filament Young''s modulus of at least about 60 million psi) and to thereby facilitate enhanced adhesion between the fibrous material and a resinous matrix material. The electrolytic process is carried out upon immersion of the fibrous material in an aqueous electrolytic solution of sodium hypochlorite (as defined) provided at a moderate temperature for a relatively brief residence time (i.e., about 2 to 10 minutes) while subjected to a relatively low current density (i.e., about 2.5 to 12 milliamps per square centimeter of surface area of fibrous material), and thereafter washing the same. Composite articles of enhanced interlaminar shear strength may be formed by incorporating the fibers modified in accordance with the present process in a resinous matrix material.

Parker James A

Papers

Electrolytic process for the surface modification of high modulus carbon fibers