Abstract: A multilayer ceramic composite is described which contains at least one supporting zone having oxidation-sensitive reinforcing fibers as well as a matrix. The matrix optionally contains oxidation-sensitive components. The composite further contains at least one surface layer, as well as at least one additional protective layer disposed between the supporting zone and surface layer, and whose matrix is composed substantially of at least one component of the matrix of the supporting zone or cover layer. The protective layer further contains additives that form self-healing layers.

Abstract: A composite pipe includes a polytetrafluoroethylene (PTFE) inner layer and a covering layer of fiber-reinforced plastics material which are joined to one another by force-locking and form-locking through an intermediate layer. The intermediate layer is formed of a PFA layer and a layer of glass or carbon fibers, in order to improve adhesive and shear strength between the PTFE inner layer and the covering layer. The PFA layer is adjacent the PTFE inner layer and the layer of glass or carbon fibers is adjacent the covering layer of fiber-reinforced plastics material.

Abstract: Bodies made of expanded graphite are impregnated with low-viscosity, solvent-free, storage-stable, polymerizing resins from the group of isocyanates and their co-reactants and/or epoxy resins up to resin contents of 50% by weight. A primary product is made of expanded graphite with an open pore system, with a particularly preferred range of bulk densities of from 0.5 to 1.3 g/cm3 and with an ash value of not more than 4% by weight. Such bodies can also contain a proportion of additives. Sealing elements, components in fuel cells and heat-conducting elements are formed of the impregnated, shaped and rapidly curable graphite bodies. A process for producing such bodies is also provided.

Abstract: A molded part of a ceramic material derived from polymers includes a composite body of a single-phase or multi-phase, amorphous, partially crystalline or crystalline matrix of silicon carbide (SiC), silicon nitride (Si3N4), silicon dioxide (SiO2) or mixtures thereof. The matrix contains graphite inclusions and the density of the ceramic material is at least 85% of the theoretical value. The molded part is produced by subjecting a mixture formed of a polymer component in an amount of 30 to 80 wt. % referred to the total weight of the mixture, fillers in an amount of 0 to 30 wt. % and graphite in an amount of 10 to 70 wt. %, to a forming process with heating to effect crosslinking of the polymer components, followed by a pyrolysis process. In particular, the molded parts are produced from polymers of the group including polysilanes, polysiloxanes, polysilazanes or polycarbosilanes. A process for producing ceramic molded parts and a sliding element having a molded part are also provided.

Abstract: Protection products and armored products made of a fiber-reinforced composite material with a ceramic matrix, include a protection element for partial or complete absorption of at least one impact-like load focussed at a point. The protection element has a body having at least one dimension at least equal to 3 cm, in a direction perpendicular to a load to be absorbed. The body includes a fiber-reinforced composite material having a ceramic matrix with at least 10% by weight of silicon carbide and having reinforcing fibers. At least 5% by weight of the reinforcing fibers are carbon fibers and/or graphite fibers.

Abstract: This invention relates to bipolar plates for electrochemical cells, particularly low-temperature fuel cells, with surface modification to enhance through-plate conductivity, processes for improving the surface properties of those bipolar plates, and fuel cell assemblies made with such plates. Graphite-polymer composite bipolar plates with high bulk conductivity are subjected to an abrasive surface treatment to improve the surface contact as well as the reactant transfer to the adjacent gas diffusion electrodes.

Abstract: A friction or sliding body includes at least two composite materials reinforced with fiber bundles and containing a ceramics matrix. A first composite material forms the outside of the sliding body as a friction layer and a second composite material forms a supporting body joined areally to the friction layer. The fiber bundle lengths of the friction layer are significantly shorter than the fiber bundle lengths of the supporting body. The fiber bundles of the friction layer have a clear alignment perpendicular to the surface. The surface of the friction layer is formed substantially only of small regions of free carbon with a diameter of at most 1.2 mm, and a total fraction of the area of free carbon on the surface is at most 35%. The surface has an extremely fine crack structure and the friction layer exhibits virtually no stresses in the vicinity of the surface. A process for producing a friction or sliding body and a brake disc or brake lining are also provided.

Abstract: A developable structural part, such as a component, includes at least one layer made from a resin-impregnated fabric (prepreg) and at least one layer made from wound threads, yarns, rovings or ribbons. At least one constant thread tension, but preferably a thread tension increasing from layer to layer, is applied during winding of the threads, yarns, rovings or ribbons. An outer ply is always formed of wound threads, yarns, rovings or ribbons. A process for producing the structural parts, a thermal insulation cylinder, a protective tube, a heating element, a stay pipe, a hot-press die and a thermal insulation element are also provided. The developable component or structural part can be obtained due to a combination of the application of fabric prepreg layers and windings made from threads, yarns, rovings or ribbons.

Abstract: A flat semi-finished product includes a filled fluoroplastics substrate in the form of a sheet, which is coated at least partially on at least one surface with a soft, thin coating of fluoroplastics. The substrate material of the sheet has a Shore-D hardness of at least 65 and the average layer thickness of the thin sheet coating is at most 20 &mgr;m. A component, in particular a flat gasket, is made from the semi-finished product. A process for the production thereof is also provided.

Abstract: A metal-reinforced layered composite includes at least one intermediate metal layer. The intermediate metal layer includes at least two at least partially overlapping metal foils which are joined to one another in an overlap region by at least one weld seam. There are no leakage channels and/or no continuous leakage channels at the weld seam of the metal foils in the longitudinal extent of the overlap region. At least one of the weld seams may have a course which at least at one point has a direction component at right angles to the longitudinal extent of the overlap region of the metal foils. The intermediate metal layer may be provided with at least one passage in the overlap region of the metal foils. A gasket, a gasket sheet, a metal layer and a method of manufacturing a layered composite are also provided.

Abstract: A flat gasket includes a gasket body and at least one eyelet enclosing the gasket body. The gasket body is formed of a pressure-resistant core which is resistant to temperatures of at least 150° C. and a covering that completely covers flat outer sides of the core and is made of a gas-tight foil of an organic polymer having a long-term temperature resistance of at least 150° C. The eyelet or eyelets enclose the gasket body with a gas-tight joining. The core is formed of a plastic or elastomer reinforced with fibers and/or fillers, or it is formed of mica or graphite. If mica or graphite are used, the core is preferably formed of layers disposed alternately on top of one another and formed of graphite foils and metal foils or layers of mica and metal foils.

Abstract: A method for the production of brake discs having friction areas made of ceramic materials, in particular composite materials, includes placing at least one ceramic portion in a diecasting mold and joining the ceramic portion with molten metals by casting under pressure into a rotationally symmetrical body which contains at least one ceramic (composite) segment that is disposed symmetrically relative to the axis of rotation of the metal body and juts out over at least one surface of the metal body perpendicular to the axis. A brake disc produced according to the method is also provided.

Abstract: This invention relates to electrode substrates for electrochemical cells, particularly low-temperature fuel cells, and processes for their production. Graphitized fiber web structures are used that have a preferred non-planar fiber alignment resulting in high through-plane conductivity. These structures are further impregnated and processed to adjust the final product properties.

Abstract: A slip-ring configuration for electric motors and generators is provided, in which brushes made of carbon materials and slip rings of a slip-ring body are electrically conductively connected to each other. The slip rings include metallic rings of standard construction as a slip-ring base and an electrically conductive sliding layer made of a graphite material. The sliding layer has a thickness which amounts to a maximum of 11% of a radius of the slip ring and is electrically conductively fastened to the periphery of the metallic slip-ring base by gluing. A method for retooling slip-ring bodies having metallic slip rings includes machining the metallic slip rings and gluing on a sliding layer.

Abstract: An internally or externally geared pump for conveying fluids lacking or only having insufficient lubricating ability, includes gearwheels moving in an operating chamber of the pump, conveying fluids and being mounted completely in parts formed of a carbon material. Supports are formed from accurately worked lateral walls and a jacket of the operating chamber formed of the carbon material. The jacket surrounds the gearwheels in the radial direction and is likewise constructed as a support. Chambers on the suction side and on the pressure side for fluid supply and fluid removal, which are necessary for the operation of the pump, are molded into side walls of the operating chamber which is formed of carbon.

Abstract: A transversely or longitudinally heated atomizing furnace for flameless atomic absorption spectrometry. The atomizing furnace has a tube furnace segment and a specimen support disposed in the tube furnace segment. The specimen support is rigidly fixed in the tube furnace. For that purpose, the specimen support has on its underside a central peg or foot which is fixed in a complementary depression or recess formed centrally in the inner wall of the tube furnace, approximately opposite the sample insertion opening. The specimen support and the tube furnace segment are formed from electrographite. The gas-accessible surfaces of the specimen support and the tube furnace segment are coated with pyrocarbon. The two members are non-detachably connected to each other by means of the pyrocarbon coating. The specimen support extends over as large as possible a portion of the length of the tube furnace. On its upper side, the specimen support is formed with a trough that can receive up to 50 .mu.