Abstract: The current-limiting resistor has two connection electrodes (1, 2) which are arranged parallel to one another as well as a resistance body (3) which has PTC behavior and with which large-area contact is made by the connection electrodes (1, 2). A varistor (40) is in electrically conductive contact with the resistance body (3). The resistance body (3) contains two contact areas (50, 51) as well as a response point (60) which is connected in parallel with the varistor (40) via the two contact areas (50, 51) and implements a PTC transition above a threshold value of a current flowing through the resistor.Since the resistance body effects the electrical contact with the varistor (40) in the case of this resistor, no metal connection electrodes are required for the varistor. At the same time, due to the outward displacement of the response point (60) away from the varistor (40), the operational reliability of the resistor is considerably improved.

Abstract: Metal-ceramic composite materials which combine advantageous properties of ceramic and metal and have the composition (Mg.sub.1-x Cu.sub.x)O+Ag.sub.y, where 0.03.ltoreq.x.ltoreq.0.25 and 0.001.ltoreq.y.ltoreq.0.5, can be produced in a one-stage process. In this process, sintering is carried out in air at a sintering temperature in the temperature range of 980.degree. C.-1100.degree. C. for a sintering time in the range of 1.5-2.5 hours. The rate of temperature rise from room temperature to the sintering temperature is in the range of 8-50 K/min. When 0.01.ltoreq.y.ltoreq.0.1, such composite materials are suitable as materials having high toughness for low-friction, self-lubricating sliding bearings, in particular of ceramic. When 0.1.ltoreq.y.ltoreq.0.2, they are suitable as electrical contact materials in fuel cells and for abrasion-resistant sliding contacts. When 0.15.ltoreq.y.ltoreq.0.5, the composite materials have a high conductivity.

Abstract: A current-limiting component having an electrical resistance body arranged between two contact terminals. The resistance body contains a first resistance material having PTC behavior. Below a limit temperature, the first resistance material has a low cold resistivity and at least one current-carrying path extending between the two contact terminals. Above the limit temperature, the first resistance material has a high hot resistivity compared with its cold resistivity. The current-limiting component has uniform switching capability and high rated current-carrying capacity despite simple and inexpensive construction. The resistance body additionally contains second resistance material having a resistivity which is between the cold resistivity and the hot resistivity of the first resistance material. The second resistance material is in intimate electrical contact with the first resistance material and forms at least one resistance path connected in parallel with the current-carrying path.

Abstract: An electric resistor has a resistor body arranged between two contract terminals. This resistor core includes an element with PTC behavior which, below a material-specific temperature, forms an electrically conducting path running between the two contact terminals. The resistor can be simple and inexpensive, but still have a high rate current-carrying capacity protected against local and overall overvoltages. This is achieved by the resistor core additionally containing a material having varistor behavior. The varistor material is connected in parallel with at least one subsection of the electrically conducting path, forming at least one varistor, and is brought into intimate electrical contact with the part of the PTC material forming the at least one subsection. The parallel connection of the element with PTC behavior and the varistor can be realized both by a microscopic construction and by a macroscopic arrangement.

Abstract: Process for the production of a polycrystalline, crystal-oriented layer of a high temperature superconductor of the class (Y,RE) Ba.sub.2 Cu.sub.3 O.sub..apprxeq.7 on a substrate or between two substrates of Ag or an Ag alloy containing up to 20% by weight Au, Pd or Pt, wherein a first powder layer, of at most 5 .mu.m thickness and consisting of the simple oxides and/or mixed oxides of the elements Y, Ba, Cu in the ratio Y:Ba:Cu:O=1:2:3:6.5, is first applied, and on it is applied a second powder layer of the superconducting substance (Y,RE) Ba.sub.2 Cu.sub.3 O.sub..apprxeq.7 in a thickness of 5-10 .mu.m, and the whole is sintered in an O.sub.2 -containing atmosphere.

Abstract: Method of applying a catalyst layer consisting of precious metals and/or precious metal compounds to a substrate of ceramic material by an electrically conducting SnO.sub.2 intermediate layer, doped with Sb, being pyrolytically applied to the surface of the substrate and subjected to an additional heat treatment for the purpose of consolidation and sintering, whereupon the catalyst layer is applied electrolytically to the intermediate layer.

Abstract: A method for purifying industrial waste water by direct oxidation of the organic pollutants in an electrochemical cell the anode of which contains, in its active part or in any intermediate layer present, neither noble metals in any form nor PbO.sub.2 nor graphite, but instead comprises in this part exclusively SnO.sub.2 which is doped with F, Cl, Sb, Mo, W, Nb, Ta or with a mixture of at least two of these elements. The anode has an oxygen overvoltage which is higher than that of a PbO.sub.2 comparison anode and reaches the value of at least 1.85 V at a current density of 0.1 mA/cm.sup.2 in 1 normal H.sub.2 SO.sub.4 under a pressure of 1 bar at a temperature of 20.degree. C. in the presence of a Pt counterelectrode.

Abstract: A voltage-dependent ceramic resistance (varistor) based on ZnO and other addition elements, mostly in the form of oxides, is prepared, in that the addition elements are added to a suspension of ZnO powder in H.sub.2 O as chemical substances in the form of aqueous, mutually compatible, non-separating solutions of organic salts, acids, complex compounds and/or colloids, the suspension/aqueous solution formed in this manner is dried in the presence of air in a spray dryer, the free-flowing powder/granules prepared in this manner are pressed to a body and the pressed body is subjected to heat treatment, in order to decompose the organic substances, convert them into oxides, remove the decomposition products, and is finally sintered by successive heating to 650.degree. C., 900.degree. C. and 1100.degree. to 1300.degree. C. The water-soluble chemical substances to be used are preferably organic salts such as formates, acetates, lactates, tartrates, citrates, ammonium citrates and ammonium tartrates.

Abstract: A collector for electric machines, including a rotationally symmetrical sintered ceramic body and a plurality of radially disposed metallic segments which are separated from each other by one interspace each and which are bonded to the ceramic body via a eutectic intermediate layer. The segments are bonded to the ceramic body in accordance with the eutectic method by being surface-oxidized on their inside narrow side and radially pressed against the ceramic body with the totality being brought to the melting temperature corresponding to the metal/metal-oxide eutectic and subsequently being cooled down again. A preferred embodiment includes: copper segments on an Al.sub.2 O.sub.3 ceramic body.

Abstract: A controllable electrochromic indicator device is disclosed which includes two electrodes, an electrochromic layer and an adjacent charge-carrier-transmitting insulator layer situated between the two electrodes and at least one of the electrodes being deposited on a supporting plate and at least one of the electrodes being transparent. The charge carrier transmitting insulator layer is a good ion conductor and functions to almost completely block the flow of electrons. At least one of the electrodes is non-polarizable and is disposed in direct contact with the ion conductor.