Abstract: A contact material, a shaped article or contact piece and a process for producing a shaped article from a contact material based on silver, include forming a powder mixture from silver and a metal oxide, and metallurgically processing the powder to form the shaped article with the metal oxide being reduced to metal. Since metal oxide powders are obtainable with a very much smaller particle size than metal powders, it is possible to obtain a contact material with a mean particle size of the metal incorporated as an active component of less than 1 .mu.m. Such a contact material has particularly favorable switching properties as a result of the fine particle size.

Abstract: Substitute materials are increasingly proposed for contact pieces in low-voltage switches, which until now frequently consisted of silver-nickel. In the case of such a substitute material which, besides silver, contains at least iron oxide (Fe.sub.2 O.sub.3 /Fe.sub.3 O.sub.4) and zirconium oxide (ZrO.sub.2) as active components, the making capacity with regard to the critical welding current is improved by an addition of a further oxide of the sixth subgroup of the Periodic System and/or of a mixed oxide that consists of iron oxide and the oxide of an element of the sixth subgroup of the Periodic System. In this connection, the further additive is, in particular, ferro-wolframate (FeWO.sub.4).

Abstract: In particular for contacts in low-voltage switches, the contact material consists of silver and further active components. In accordance with the invention, there are present as active components, in combination, iron oxide (Fe.sub.2 O.sub.3 /Fe.sub.3 O.sub.4) in a proportion of between 1 and 50% by weight and at least one oxide of a further chemical element in a proportion of between 0.01 and 5% by weight. In particular, contact materials of the constitution AgFe.sub.2 O.sub.3 ReO.sub.2 and AgFe.sub.2 O.sub.3 ZrO.sub.2 have proven suitable in practice. The manufacture of the material and fabricating of the contacts can be effected by methods of powder metallurgy with the inclusion of molding or extrusion technique.

Abstract: In a known process, oxide powders derived from the four-component systems yttrium-barium-copper-oxygen or lanthanum-strontium-copper-oxygen are mixed, pressed, sintered, ground and then heat-treated to produce a superconducting material which can be shaped to the desired cross-section. According to the invention, the powder is compacted by isostatic pressing and the blank so obtained is extruded at a temperature.gtoreq.500.degree. C. to form a metallic sheath with a deformation ratio of at least 50%. The extruded blank is then converted to wire or strip. The current-carrying capacity of the high-temperature superconductor is improved by the extrusion and the resulting alignment of the crystallites. The process can be implemented using known high-temperatures superconducting material.

Abstract: A device for manufacturing a laminated semifinished material by indirect extrusion of a sintered-bond blank consisting of layers of metal, metal alloys, metal mixtures or mixtures of metals and nonmetals comprises a vessel with a rectangular cutout or extrusion chamber and a one- or multipart extrusion die with one or several cutouts. A surface of the die facing the blank is profiled in the form of one or more roof gables, the surfaces of which gable forms extend perpendicularly towards the cutout from a sliding surface of the extrusion die.