Abstract: A superconductive element is described, comprising a rigid support made of a non-superconductive material, said support comprising at least one superconductive track formed by a groove containing a superconductive material having a density equal to at least 85% of the value of its theoretical density, and the process for producing said element. The present invention also relates to the possible uses of the superconductive elements, and also to superconductive devices comprising said superconductive elements.

Abstract: A superconductive element is described, comprising a rigid support made of a non-superconductive material, said support comprising at least one superconductive track formed by a groove containing a superconductive material having a density equal to at least 85% of the value of its theoretical density, and the process for producing said element. The present invention also relates to the possible uses of the superconductive elements, and also to superconductive devices comprising said superconductive elements.

Abstract: A process is described for the preparation of magnesium borohydride having a high purity and crystallinity, which comprises the reaction of an orgenometallic compound of magnesium of the type MgX2, wherein X is an organic binder selected from alkyl, amide, alkoxide, cyclopentadienyl, aryl, with a derivative of a boron hydride, in a hydrocarbon solvent.

Abstract: A method is described for the preparation of superconductor massive bodies of MgB2, having a density close to the theorical value, which comprises the following passages: mechanical activation of crystalline boron with the formation of activated powders; formation of a porous preform of said powders; assembly of the porous boron preform and massive precursors of metallic magnesium in a container and sealing thereof in an atmosphere of inert gas or with a low oxygen content; thermal treatment of the boron and magnesium as assembled above, at a temperature higher than 700° C. for a time greater than 30 minutes, with the consequent percolation of the magnesium, in liquid phase, through the activated crystalline boron powders.

Abstract: A process is described for the preparation of magnesium borohydride having a high purity and crystallinity, which comprises the reaction of an orgenometallic compound of magnesium of the type MgX2, wherein X is an organic binder selected from alkyl, amide, alkoxide, cyclopentadienyl, aryl, with a derivative of a boron hydride, in a hydrocarbon solvent.

Abstract: A method is described for the production of superconductive wires based on hollow filaments made of MgB2, which comprises: a) the formation of a composite billet by means of the coaxial insertion in a tubular metallic container of a cylindrical bar made of metallic magnesium and amorphous boron powder in the interspace between the container and bar, said powder being pressed between the metallic container and the magnesium bar, in such a quantity that the weight ratio magnesium/boron is higher than 1.2; b) at least one plastic deformation treatment of the composite billet thus obtained until a wire with a pre-fixed diameter is obtained, with the subsequent winding of the wire onto a support; c) a thermal treatment of the filament product thus obtained, at a temperature ranging from 700° C. to 950° C. for a time ranging from 15 minutes to three hours.

Abstract: A method is described for the production of superconductive wires based on hollow filaments made of MgB2, which comprises: a) the formation of a composite billet by means of the coaxial insertion in a tubular metallic container of a cylindrical bar made of metallic magnesium and amorphous boron powder in the interspace between the container and bar, said powder being pressed between the metallic container and the magnesium bar, in such a quantity that the weight ratio magnesium/boron is higher than 1.2; b) at least one plastic deformation treatment of the composite billet thus obtained until a wire with a prefixed diameter is obtained, with the subsequent winding of the wire onto a support; c) a thermal treatment of the filament product thus obtained, at a temperature ranging from 700° C. to 950° C. for a time ranging from 15 minutes to three hours.

Abstract: A method is described for the preparation of superconductor massive bodies of MgB2, having a density close to the theorical value, which comprises the following passages: mechanical activation of crystalline boron with the formation of activated powders; formation of a porous preform of said powders; assembly of the porous boron preform and massive precursors of metallic magnesium in a container and sealing thereof in an atmosphere of inert gas or with a low oxygen content; thermal treatment of the boron and magnesium as assembled above, at a temperature higher than 700° C. for a time greater than 30 minutes, with the consequent percolation of the magnesium, in liquid phase, through the activated crystalline boron powders.

Abstract: A method is described for the production of superconductive wires based on hollow filaments made of MgB2, which comprises: a) the formation of a composite billet by means of the coaxial insertion in a tubular metallic container of a cylindrical bar made of metallic magnesium and amorphous boron powder in the interspace between the container and bar, said powder being pressed between the metallic container and the magnesium bar, in such a quantity that the weight ratio magnesium/boron is higher than 1.2; b) at least one plastic deformation treatment of the composite billet thus obtained until a wire with a pre-fixed diameter is obtained, with the subsequent winding of the wire onto a support; c) a thermal treatment of the filament product thus obtained, at a temperature ranging from 700° C. to 950° C. for a time ranging from 15 minutes to three hours.

Abstract: A description follows of an article based on a nickel-chromium-silicon metal alloy, including microcrystalline borides, obtained by the rapid solidification and subsequent thermal treatment of a nickel-chromium-boron-silicon metal alloy comprising from 39.0 to 69.4 atom % of nickel, from 11.8 to 33.9 atom % of chromium, from 7.6 to 27.4 atom % of boron and from 7.6 to 17.5 atom % of silicon. The above article is preferably a tape or a sheet or a fiber having high mechanical properties and is particularly resistant to oxidation.

Abstract: Thermotropic melt processable liquid crystalline aromatic polyesters comprising units derived from a dicarboxylic acid and from a mixture of aromatic diols in which from 50% to 80% is (1-phenylethyl)hydroquinone and from 20% to 50% is hydroquinone.

Abstract: Preforms for metal matrix composites consisting of ceramic material belonging to the class of oxides, nitrides, carbides, borides, oxynitrides and the like, prevailingly in an acicular form and having monocrystalline or polycrystalline structure, having a density ranging from 0.2 to 1.6 g/cm.sup.3 and porosity ranging from 50 to 95%.

Abstract: A process for the production of primarily syndiotactic vinyl aromatic polymers by polymerizing or copolymerizing vinyl aromatic monomers such as styrene or styrene derivatives in the presence of a catalyst system comprising the product of the reaction between:a) a compound of a transition metal (M) different from titanium and containing at least a bond M-O, M-C, M-N, M-P, M-S or M-halogen, andb) an organoaluminum compound containing at least an oxygen atom bound to the aluminum atom or bound between two aluminum atoms.Compound a) can be used as such or may be supported on a suitable carrier.

Abstract: Refractory and electroconductive ceramic compositions having a density higher than 4 g/cm.sup.3, ultimate tensile strength higher than 250 MPa, Vickers microhardness higher than 1000 kg/mm.sup.2 and electric resistivity lower than 600 microohm.cm, essentially consisting of alumina and of a nitride component of at least one transition metal belonging to groups IVB, VB or VIB of the Periodic Chart of the Elements.

Abstract: Compositions comprising from 5 to 50% by weight of a polyphenylene ether and from 95 to 50% by weight of a styrene polymer having a syndiotactic structure. Such compositions are endowed with enhanced mechanical properties compared to those containing amorphous polystyrene, or polystyrene having an isotactic structure.

Abstract: Polyacetylene having an apparent density at 20.degree. C. greater than 0.6 g/ccm and a surface area below 60 m.sup.2 /g is prepared by polymerizing gaseous acetylene in the presence of a catalytic system consisting of:(a) an oxygenized compound of Ti or V, containing at least one metal-oxygen bond;(b) an organometallic compound of aluminum containing at least one hetero-atom, of the formula: ##STR1## wherein: ##STR2## while R=a hydrocarbon radical with 1-18 carbon atoms, and where R'.dbd.R, or halogen or alcoxyl.