Abstract: The invention relates a powder in tube type method of making an HTc superconductive multifilament strand having a silver-based matrix, in which: a first envelope is filled with powder reagents for an HTc superconductor; the resulting billet is drawn down into a monofilament strand; said monofilament strand is cut up into lengths and a secondary envelope is filled with the resulting lengths, thereby making a multifilament billet which is drawn down into a multifilament strand; said multifilament strand is cut up into lengths and a new envelope is filled with the resulting lengths, thereby making a new multifilament billet which is drawn down into a new multifilament strand; and it is shaped and subjected to heat treatment; according to the invention, at least one face of the monofilament strand is electrically insulated; and during the first multifilament step the secondary envelope is filled with the resulting insulated lengths.

Abstract: The invention relates a powder in tube type method of making an HTc superconductive multifilament strand having a silver-based matrix, in which:

Abstract: The invention relates a powder in tube type method of making an HTc superconductive multifilament strand having a silver-based matrix, in which: a first envelope is filled with powder reagents for an HTc superconductor; the resulting billet is drawn down into a monofilament strand; the monofilament strand is cut up into lengths and a secondary envelope is filled with the resulting lengths, thereby making a multifilament billet which is drawn down into a multifilament strand; the multifilament strand is cut up into lengths and a new envelope is filled with the resulting lengths, thereby making a new multifilament billet which is drawn down into a new multifilament strand; and it is shaped and subjected to heat treatment; according to the invention, at least one face of the monofilament strand is electrically insulated; and during the first multifilament step the secondary envelope is filled with the resulting insulated lengths.

Abstract: A process for texturing an HTc superconductor of the matrix type based on silver and the superconductor material (Bi.sub.1-x Pb.sub.x).sub.2 Sr.sub.2 Ca.sub.y Cu.sub.1+y O.sub.6+2y where x.epsilon.[0; 0,4] and y.epsilon.{0, 1, 2} includes the following steps carried out in succession: raising the temperature of the superconductor from room temperature to the melting point of the superconductor material, maintaining the temperature of the superconductor constant at the melting point of the superconductor material for a relatively short period, varying the temperature of the superconductor between the melting point of the superconductor material and its synthesis temperature, maintaining the temperature of the superconductor constant at the synthesis temperature of the superconductor material for a relatively long period and reducing the temperature of the superconductor from the synthesis temperature of the superconductor material to room temperature.

Abstract: A sheathed twisted superconductor with a high critical temperature is made from a billet obtained by assembling square cross-section single strands in a square cross-section metal tube. The multistrand obtained by drawing the billet through a roller die is twisted with a particular lay and rolled using rollers the diameter of which is much greater than the twist lay. The sheathed twisted superconductor obtained by this method is intended for variable current applications.

Abstract: In a method for the manufacture of an encased high critical temperature superconducting wire by the "powder in tube" method, prior to the introduction of a compressed rod of superconducting material into a silver tube, the rod is heat treated so that grains of unwanted phase are reabsorbed. The tube can be drawn more easily, and strands can be produced with a regular geometry and no defects. The wire is constituted by 15 .mu.m to 20 .mu.m thick filaments (30) with a form factor of more than 60.

Abstract: A superconducting strand comprises a central superconducting filament (1), a covering (2) of oxide for ensuring sufficient oxygen pressure around the filament (1), a layer of cladding (3) made of aluminum, an alloy of copper and aluminum, or of stainless steel, a layer of cladding (4) made of niobium, of tantalum, or of vanadium, and an outer covering of copper (5).

Abstract: The method is intended to provide cables (10) having an optical fiber (1) and suitable for mechanically severe environments, while remaining small in section. Heretofore, the mechanical strength of optical fiber cables has been obtained by plastic structures of considerable cross-sectional area and reinforced by metal strands or by glass fibers. In the method of the present invention, the reinforcing is obtained by metal composites (3) having very high mechanical strength and very small diameter, said composites extending parallel to the fiber (1).