Abstract: Flat and slightly convex pyrolytic graphite grid electrodes are very suitable for use in electric discharge tubes, are example in ion sources, cathode-ray tubes, travelling waveguides and transmitter tubes. It has proved possible to manufacture such electrodes by manufacturing the grid and the grid holder of the pyrolytic graphite electrode from one piece of pyrolytic graphite. Such integral grid electrodes have very good mechanical and thermal properties.

Abstract: A basic body for an anode disc is provided with laminations which are situated at a short distance from one another. Pyrolytic graphite is provided in the narrow intermediate spaces between the laminations by deposition of carbon from the gaseous state. Because of the small distances between laminations, these intermediate spaces are quickly filled with pyrolytic graphite.

Abstract: Method and equipment for the manufacture of glass bodies wherein a porous green body is formed by extrusion from the starting material for the glass body in the form of a plastic mass and this green body is then purified and sintered, the plastic mass being transformed into a state of reduced viscosity by the application of mechanical forces utilizing the thixotropic effect and being extruded in this state.

Abstract: In a heating device for atomic absorption spectrometers with electrothermal excitation of a sample, a tubular body for receiving the sample comprises a radial aperture (15) for introducing the sample at the central part of the tubular body. A pair of contacts (1, 2) can be cooled comprise current supplies (3), each consisting of a detachable upper part (5) and a fixed lower part (6) with the upper part and the lower part being connected together so as to be detachable. Each contact comprises an aperture (9) which is coaxial with the tubular body with the apertures extending partly in the upper part and partly in the lower part of the contacts and holding the ends of the tubular body. Damage and deformations of the contacts are avoided in that the diameters of the apertures (9), with the upper parts (5) laid flush on the lower parts (6), are shorter in the vertical direction than in the horizontal direction.

Abstract: A cuvette consisting of a basic hollow member of pyrolytic graphite which is treated at least on the outside surface by a local mechanical abrasion is provided for use in atomic absorption spectroscopy. Since the mechanically treated surfaces may form the inner and outer surfaces of the cuvette, it has been found that the cuvette need not be after-coated or sealed with pyrolytic graphite, but may be of a finally finished form following this mechanical abrasion. Accordingly, cuvettes of substantially smaller wall thicknesses, and substantially smaller mass, are formed with the same or even increased rigidity than commercially available graphite cuvettes which may have or not have a pyrolytic graphite coating.

Abstract: A cuvette for atomic absorption spectrometry includes a tube of pyrolytic graphite, electrographite or vitreous carbon with flanges provided at the ends of the tube, or in the proximity thereof, and having a common envelope of pyrolytic graphite. The flanges consist of solid layers of pyrolytic graphite in which the layer planes of the pyrolytic graphite are either directed perpendicularly to the longitudinal axis of the tube, or extend everywhere parallel to the longitudinal axis and the surface of the tube. Cuvettes with flanges having an orientation of the solid layer planes directed perpendicularly to the longitudinal axis of the tube are considered and operate as "fast", whereas those having an orientation extending everywhere parallel to the longitudinal axis are considered.

Abstract: A cuvette having a thin-walled basic member of pyrolytic graphite is provided with annular graphite components in proximity to its ends. These parts are connected to form a unit which is further coated by an enveloping pyrolytic graphite coating. This cuvette having flanged parts is simpler to electrically contact and is mechanically stable.

Abstract: The atomizer of the present invention serves for generating free atoms and an atomic cloud by heating a sample for analysis. The device includes a preferably tubular cuvette for receiving the sample, and the cuvette consists either of a basic body of carbon, which is enveloped by a pyrolytic graphite layer, or only of pyrolytic graphite layers. An electric supply unit for Joule heating the cuvette is in contact with the cuvette by contact members. In order to achieve a radial temperature distribution in the cuvette such that the inner wall of the cuvette is at an essentially higher temperature than the outer wall of the cuvette, the contact surfaces of the cuvette and the contact surfaces of the contact members contact each other in such a manner that the electric current applied during operation of the atomizer preferably flows through the inner wall of the cuvette.

Abstract: A method of making crucibles for flameless atomic spectroscopy comprises coating carbon crucible preforms with pyrolytic graphite in a reaction vessel by deposition of the graphite from a gas phase wherein the carbon crucible preforms are removed from the reaction vessel after cooling to room temperature and are re-introduced into the reaction vessel orientated in different positions before application of a second or subsequent coating to give a total thickness of the coatings of 20 to 80 .mu.m.

Abstract: A layer of pyrolytic graphite is deposited on the surface of the basic body of the anode of a rotary-anode X-ray tube. On the layer of pyrolytic graphite there is provided a further layer of a high-melting metal on the surface of which the focal path extends during operation of the tube. A basic body which has substantially all advantages of the pyrolytic graphite but whose manufacture is much simpler, faster and hence also more economical than an equivalent carrier body comprising a ring of solid, thick-walled pyrolytic graphite, is obtained in that the basic body consists of a lamination of graphite foils at least in the region beneath the focal path.

Abstract: A rotary anode comprising a basic body of carbon whose surface is provided with a pyrolytic graphite coating having a crystallographic layer structure. A metallic layer of high-melting temperature, in which X-rays are generated during operation in an X-ray tube, is provided on the body. The metallic layer and the pyrolytic graphite coating have a common contact face which cuts through the crystallographic layers in the pyrolytic graphite. Heat developed in the metallic layer is discharged through the face into the pyrolytic graphite layers.

Abstract: A preform made of carbon, and especially electrical graphite (electro-graphite), is given a protective coating of pyrolytic graphite which, in turn, is activated by further coating with a carbon with a very low degree of orientation (soot) or by roughening. The process of activation reduces the effect of the sample to be analysed, while the protective effect of the pyrolytic graphite coating is preserved.

Abstract: In a rotary anode X-ray tube, comprising an anode disc which is mounted on a rotary shaft and which comprises a basic body of graphite, the anode disc is subject to such loads during the operation of the X-ray tube that a connection between the disc and the shaft is liable to fracture if it consists of pressed and sintered graphite. In order to counteract fracturing, the basic body is connected to the shaft by a bushing of pyrolytic or microporous graphite. A pyrolytic graphite bushing may be formed by deposition from the gaseous phase in situ or on a mandril, and should have a radial direction of growth. Both materials have a high strength and, moreover, a lower thermal conductivity in the radial direction. As a result, not only is the strength improved, but the thermal loading of the shaft bearings is also reduced.

Abstract: The yield of good-quality bodies consisting of vitreous carbon is increased to substantially 100% when the pyrolysis is performed in a reaction vessel in which a collecting container or a collecting disc for the condensable volatile decomposition products which is open at its upper side is arranged above the polymeric substances to be pyrolyzed. The collecting disc divides the interior of the reaction vessel into two parts, a passage for gases remaining between the upper part and the lower part. During the pyrolysis, a spatial temperature distribution is adjusted in the reaction vessel which results in a pulsating evaporation and condensation of the decomposition products, so that the decomposition products are completely removed.

Abstract: An intermediate layer comprising several sub-layers is sandwiched between the support and a target layer of a rotary X-ray anode. The sub-layer of the intermediate layer which contacts the support and the sub-layer of the intermediate layer which contacts the target layer both consist of pure rhenium. Interposed between these two sub-layers is a further sub-layer consisting of a rhenium alloy containing at least one carbide-forming metal, for example tungsten, tantalum or hafnium. This construction of the intermediate layer provides a barrier against carbon diffusion, which barrier has substantially the heat conduction properties of metals and which offers a sufficient protection against the penetration of carbon into the target layer, even at temperaturers above 1500 K.

Abstract: The focal path (4) of an anode disc in accordance with the invention is provided on a pyrographite ring (1) which is oriented so that the surfaces of higher thermal and electrical conductivity extend parallel to the axis of rotation (3) of the anode disc. As a result, suitable removal of heat can be ensured without thermal overloading of the bearings.

Abstract: The life of AAS cuvettes coated with pyrolytic graphite is increased to more than 3000 injections when the coated substrata are additionally coated at least once with pyrolytic graphite, pyrolytic graphite layers having an overall thickness of 20-80 .mu.m then being applied.

Abstract: The yield of good-quality bodies consisting of vitreous carbon is increased to substantially 100% when the pyrolysis is performed in a reaction vessel in which a collecting container or a collecting disc for the condensable volatile decomposition products which is open at its upper side is arranged above the polymeric substances to be pyrolized. The collecting disc divides the interior of the reaction vessel into two parts, a passage for gases remaining between the upper part and the lower part. During the pyrolysis, a spatial temperature distribution is adjusted in the reaction vessel which results in a pulsating evaporation and condensation of the decomposition products, so that the decomposition products are completely removed.

Abstract: Cathodes having a support for emissive material of foamed carbon are mechanically stable and resistant to detrition and have a homogeneous pore distribution.

Abstract: Cuvettes of carbonized laminated fabric with a surface layer of pyrolytic graphite are easy to manufacture, have a high mechanical rigidity and no memory effect and enable the operation of analysis apparatuses at normal mains voltage (220 V).