Abstract: A method for producing an implant whose surface is roughened by the sandblast method using shot material containing fluoroapatite. Fluoroapatite, compared to hydroxyapatite, has poor biocompatibility, but is superior in hardness. It also has a property of being dissolved in acid. As a result, by the sandblast method using shot material containing fluoroapatite, the surface roughening is performed quite effectively, and shot materials remained on the surface can easily be removed by acid.

Abstract: A method for producing an implant whose surface is roughened by the sandblast method using shot material containing fluoroapatite. Fluoroapatite, compared to hydroxyapatite, has poor biocompatibility, but is superior in hardness. It also has a property of being dissolved in acid. As a result, by the sandblast method using shot material containing fluoroapatite, the surface roughening is performed quite effectively, and shot materials remained on the surface can easily be removed by acid.

Abstract: A process for preparing carbon fibers wherein carbon fibers are prepared from the mesophase-pitch containing not more than 80% by weight of a quinoline-insoluble component and showing, under a polarization microscope, more than 70% of optically anisotropic region, comprising the steps of subjecting a mesophase-pitch showing a viscosity of 10 to 100 poise at a temperature of spinning of 330.degree. to 450.degree. C., to rotating-centrifugal-spinning in a rotating-centrifugal spinning machine with a peripheral velocity of rotating nozzle thereof of 300 to 1000 m/min and exposing the thus spun fibers of the mesophase pitch to a flow of a gas spouting into a spinning direction at a temperature of 280.degree. to 400.degree. C. and at a linear velocity of 50 to 200 m/sec, thereby preparing carbon fibers showing a random-mosaic structural pattern in cross section thereof perpendicular to fiber axis.

Abstract: An electrode substrate for a fuel cell having a high porosity, a good mechanical strength and electroconductivity and a sharp distribution of pore radii is prepared by a process comprising mixing 30 to 50% by weight of carbon fiber, 20 to 50% by weight of a binder and 20 to 50% by weight of an organic granule, press-shaping the resultant mixture, curing the shaped product and calcinating the cured product.

Abstract: An artificial dental root comprised of a particulate or powdered form of synthetic hydroxyapatite or calcined or sintered synthetic hydroxyapatite or a mixture thereof and an organic matrix, the surface area of said artificial dental root to be brought into contact with a bone being composed of both a phase of said hydroxyapatite and a phase of said organic matrix. The artificial dental root is prepared by blending said hydroxyapatite with said organic matrix and molding the blend. The artificial dental root has moderate affinity for a bone and high mechanical strength.

Abstract: Disclosed herein is an organic friction material comprising 5 to 25% by volume of metallic fiber, 3 to 40% by volume of activated carbon, 3 to 15% by volume of carbon fiber, 7 to 47% by volume of an organic and inorganic filling material and 10 to 30% by volume of phenolic resin.

Abstract: Disclosed herein are shaped articles of porous carbon comprising carbon fibers having a compression strength of higher than 50 kg/cm.sup.2 and a porosity of 50 to 80%, in which radii of not less than 60% of the pores are distributed in a range wherein the difference between the upper pore radius and the lower pore radius is 20 microns.

Abstract: Disclosed herein is an organic friction material comprising 5 to 25% by volume of metallic fiber, 3 to 40% by volume of activated carbon, 3 to 15% by volume of carbon fiber, 7 to 47% by volume of an organic or inorganic filling material and 10 to 30% by volume of phenolic resin.

Abstract: An organic friction material having favorable mechanical, thermal and frictional properties and comprising phenolic resin, carbon fibers, steel fibers and filler is disclosed, the organic friction material not containing any asbestos.

Abstract: A method for manufacturing graphite whiskers which comprises: mixing one or more of gasified compounds having a condensed polycyclic structure of two to five benzene rings with a large amount of inert gas containing a small amount of CO, CO.sub.2 or H.sub.2 O; heating said gas mixture at 700.degree. to 1200.degree. C and a substantially atmospheric pressure to generate precursory carbon whiskers comprised of numerous carbon crystals orientated in a form of single sheet which is rolled up like a scroll or a plurality of separate sheets rolled in concentric relationships; and graphitizing said carbon whiskers at temperatures of 2700.degree. to 3000.degree. C in an atmosphere of inert gas.

Abstract: A carbon fiber is oxidized to form oxygen-containing functional groups on the entire surface of the fiber and then contacted with ammonia, an organic amine, a lactam, or an amino carboxylic acid at a temperature of 100.degree.-500.degree. C whereby the surfaces of the carbon fiber obtain good affinity for a synthetic resin.