Rapid resistive consolidation of YBa2Cu3O7 powder
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Resistance heating by passage of direct current with simultaneous application of pressure had previously proven to be a very fast means of consolidation of YBa2Cu3O7 powder. This work extended the technique to the rapid production of larger, high density specimens and solved problems of poor surface quality. Improved procedure and equipment produced cylindrical specimens 13 mm in diameter by 10 mm in length. A 5 min processing time produced a density of 81% (low density), and 15 min produced a density of 91% of the theoretical maximum (high density). Oxygen annealed specimens exhibited the Meissner effect, had a transition temperature of 94 K, and had a critical current density of 130 A/cm2. High density specimens had large grain size and little porosity. Low density specimens were 100% YBa2Cu3O7, while high density specimens contained CuO and BaCuO3, indicating localized melting and the need for closer temperature control. Specimens were suitable for feed rod or crucible blanks for the laser heated pedestal growth (LHPG) method. Rapid heating and concentration of heat and pressure in the region of powder particles where sintering occurs are great advantages over conventional methods.
KeywordsCritical Current Density Sinter Time Silver Paint Meissner Effect Material Shaping Technology
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