THE SINTERING KINETICS OF AG-Y1BA2CU3O7-DELTA LAMINATES AND THE INTERFACIAL METAL-CERAMIC REACTION

The tape casting technique was successfully applied for making Ag-Y1Ba 2Cu3O7-delta laminates having alternative layers of Ag and Y1Ba2Cu3O7- delta (YBC), forming a YBC/Ag/YBC/Ag/ YBC multilayer composite. For th e Ag-YBC composite two well differentiated temperature ranges for dens ification were observed. A low temperature range from 200 to 800 degre es C, where the principal densification could be assigned to the silve r part of the structure, and a high temperature range where the main d ensification features of YBC were still observed for the Ag-YBC lamina tes. Silver provoked a noticeable decrease in the ''on-set'' temperatu res for each one of the regimes operating in the densification of YBC. From kinetic analysis, it may be advanced that silver alters signific antly the diffusivities in the YBC ceramic system. For temperatures in the range 500-600 degrees C, the Ag and the YBC ceramic were found to react to a significant extent causing decomposition of YBC close to t he interface. At the interface on the YBC ceramic side, we observed Ba CuO2 and CuO grains containing Ag. After treatment we observed an inte rface on the Ag side with silver grains much smaller in size than thos e in the bulk of the Ag layer.