25 research outputs found
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Explosive consolidation of (Bi,Pb)-Sr-Ca-Cu-O superconductor powders during powder-in-tube processing
Superconducting (2212) Bi-Sr-Ca-Cu-O (BSCCO) and BSCCO-Ag composites were explosively consolidated in silver tubing and then drawn and rolled into tapes. The silver-sheathed tapes were then subjected to repeated cycles of pressing and heat treatment, which resulted in enhanced texturing and grain growth and a subsequent increase in critical current density (J{sub c}). The effect of silver flake additions to the superconducting powder further increased texturing and J{sub c}, with optimal properties occurring in powders with 10 vol.% silver flake. Density measurements on the superconductor tapes showed that near-theoretical densities had been achieved at the end of the thermomechanical treatment (TMT). Scanning electron microscopy indicated that grain alignment increased after TMT, with an apparent reduction in grain size after the fourth treatment. X-ray diffraction studies showed that grain orientation and conversion of 2212 to Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10{minus}x} are improved when explosive consolidation is introduced before the drawing step in the powder-in-tube process
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Effect of shock loading on critical current density of BSCCO/Ag tapes
Shock-loading has been used to introduce a variety of defects into superconducting BSCCO/Ag tapes. In theory, these defects will pin the movement of flux in these superconductors, allowing higher current densities to be passed through them. The tapes in the present study have been subjected to different peak shock pressures and pulse durations. Critical current density (J{sub c}) and magnetization measurements have been made on shock-loaded and pressed samples. The shocked samples have shown a degradation of transport current properties, but have maintained their high transition temperatures. It is thought that a postshock annealing to heal the microcracks in the material may improve the superconducting transport properties. It is also believed that the pressures to which these tapes were subjected completely saturated the material with defects. Investigation of the use of lower pressures may be advisable
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Characterization of plasma sprayed and explosively consolidated simulated lunar soil
Two methods for the use of lunar materials for the construction of shelters on the Moon are being proposed: explosive consolidation of the soil into structural components and plasma spraying of the soil to join components. The plasma-sprayed coating would also provide protection from the intense radiation. In this work, a mare simulant was plasma-sprayed onto a stainless steel substrate. Deposition of a 0.020 inch coating using power inputs of 23, 25, 27 and 29 kW were compared. Hardness of the coatings increased with each increase of power to the system, while porosity at the interface decreased. All coatings exhibited good adhesion. Simultaneously, an explosively consolidated sample was similarly characterized to afford a comparison of structural features associated with each mode of proposed use