Abstract: The present invention relates to an electrical contact material comprising a matrix made of conductive metal and an unstable fraction incorporated into this matrix. The unstable fraction has the property of decomposing between the operating temperature of the electrical contact and the melting point of the metal with the release of a gas capable of destabilizing an electric arc.

Abstract: The invention relates to a method of producing a sheath for a high-temperature multifilament superconducting cable. According to the invention, the sheath is obtained through the co-extrusion of a cylindrical billet (50) comprising at least two concentric cylinders (52, 54, 56). The invention also relates to a sheath for a high-temperature multifilament superconducting cable which is produced using the aforementioned method. The inventive sheath consists of a tube (10) with a multi-layer wall comprising: a pure silver inner layer (12, 16, 22) and at least one second silver-based alloy layer (14, 18, 24, 26).

Abstract: A method for producing a contact material made of copper and chromium in a proportion of 40 to 75 wt.-% copper and 25 to 60 wt.-% of chromium for contact pieces for vacuum switch devices by pressing the powder mixture, sintering and infiltrating the compact and subsequent reshaping into a semi-finished contact material product having a density which corresponds to at least 99% of the theoretical density, as well as to contact pieces made of this semi-finished contact material product.

Abstract: A method for producing a contact material made of copper and chromium in a proportion of 40 to 75 wt.-% copper and 25 to 60 wt.-% of chromium for contact pieces for vacuum switch devices by pressing the powder mixture, sintering and infiltrating the compact and subsequent reshaping into a semi-finished contact material product having a density which corresponds to at least 99% of the theoretical density, as well as to contact pieces made of this semi-finished contact material product.

Abstract: A process for producing a product made of a contact material. The contact material is formed of a powder mixture containing silver and iron as a main active component. The iron is an iron powder having an average particle size in excess of 1 .mu.m. Further processing of the powder mixture using powder metallurgy methods are performed for forming a product in which the iron has been oxidized to an iron oxide.

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: Contact material based on silver, use of such a contact material in a switching device in power engineering, and process for preparing the contact material.For contact pieces in low-voltage switches, in particular, substitute materials based on silver-iron oxide are proposed for the silver-nickel hitherto often used in practice. According to the invention, such a material contains, as a further effective component, an oxide of a metal of the third sub-group, yttrium oxide (Y.sub.2 O.sub.3) being especially designed for this purpose. For example, a material of the composition Ag/Fe.sub.2 O.sub.3 10/Y.sub.2 O.sub.3 1 meets, with its favourable temperature behaviour, the properties required with respect to the contact property spectrum. In addition, at least one metal oxide which contains elements of the sixth sub-group of the Periodic Table of the Elements, preferably iron tungstate (FeWO.sub.4), can be present. In particular, a material of the composition Ag/Fe.sub.2 O.sub.3 9/Y.sub.2 O.sub.3 1/FeWO.sub.4 0.

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: A contact facing is normally bonded to the carrier by brazing or welding, for which purpose, the bonding side has to have a suitable layer. According to the invention, prior to the bonding operation, the contact facings are treated without fusion in such a way that the metal oxide is at least partially reduced to metal at least on the solder side at the surface and in the subsurface region of the contact facing. The reduction can be carried out by heat treatment in reducing atmosphere. In the case of contact materials based on silver/iron oxide (AgFe.sub.2 O.sub.3 /Fe.sub.3 O.sub.4), in particular, the iron oxide may also be reduced to iron on the switching side since iron oxide is again formed after switching. Alternatively, contact facings may be provided with carbon as reducing agent on the solder side. In particular, the reduction may take place locally in this case.

Abstract: Contacts such as contact points, contact strips, or contact sections are usually provided with hard solder on a copper-silver basis in the form of a flat solder layer. The contact is then connected over this solder layer with a contact carrier. The solder layer is melted, whereupon the free surface of the solder layer (13, 130) is covered during melting with a material (1, 5, 15) that has no solubility with silver or copper. The material can, during melting of the solder, form a covering (1, 15) beneath the contact (10, 12, 100) provided on its solder side with the solder layer (13, 130) or can also form a covering over the contact (10, 12, 100) provided on its solder side with the solder layer (13, 130). As materials for covering the solder layer (13, 130), high-melting metals, preferably tantalum, or a ceramic are used.

Abstract: Contact materials with the composition AgSnO.sub.2 Bi.sub.2 O.sub.3 CuO have proven themselves, particularly for low-voltage switching devices. These materials can contain an additive of other metal oxides. In addition to the required useful lifetime and suitable excess high temperature behavior, such materials are also supposed to fulfill all the requirements under short-circuit current stress. This is accomplished, according to the invention, in that the additional metal oxide is separately added stannic oxide and/or iron containing at least one element of the sixth sub-group of the periodic system. In the sintered composite material according to the invention, the other metal oxide is particularly ferric tungstate (FeWO.sub.4). Preferably, separately added SnO.sub.2 is present in combination with 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: The contact material in particular for contacts in low-voltage switches consists of silver and further active components. In accordance with the invention, iron (Fe) in proportions of between 1 and 50% by weight and rhenium (Re) in proportions of between 0.01 and 5% by weight are present in combination as active components. The manufacture of the material and the fabricating of the contacts can be effected by methods of powder metallurgy with inclusion of molding or extrusion techniques, the active components being used in the form of separate powders, as fusible alloy or as mechanically alloyed powder.

Abstract: Particularly in the case of contacts consisting of a silver-metal oxide-(AgMeO)-based material which are provided on their the back side with solder, it is noted, upon hard soldering, on a contact base that solder can ascend in undesired manner up to the contact surfaces. This is due to the heating upon the hard soldering. In accordance with the invention, the wettability of the side surfaces of the contacts is reduced to such an extent that the ascent of solder to the surface on the contact mating area is avoided. For this purpose, metal oxides are preferably introduced into the surfaces of the contacts. In the case of contacts having a base of silver-metal oxide (AgMeO), metal oxides which are already contained as active elements in the material can preferably be used.

Abstract: Purely powder-metallurgical processes or sinter-impregnation processes are often used to manufacture CuCr contact materials. Here the aim is to obtain the lowest possible residual porosity, which should be <1%. According to the invention, a powder moulding of the components is densified in two stages; the first stage is a sintering process with a densification of the sintered body to a closed porosity, and the second stage is a hot-isostatic pressing operation (HIP), in which the unencased workpieces are taken to a final density amounting to a space occupation of at least 99%. Thus, an economical method of manufacturing high grade material is obtained. It is possible to produce multi-layer contacts or self-adhesive bonds between the sintered body and a solid substrate, e.g. a copper contact bolt.