RESISTENCIA AL CORTE DE UNIONES Al 2 O 3 -Nb PRODUCIDAS POR SOLDADURA FUERTE USANDO UNA ALEACIÓN Cu-Zn COMO ELEMENTO DE UNIÓN

Abstract

Metal brazing is a widely used technique to join advanced ceramics and metal. In this study, we have investigated the microstructure and mechanical properties of Al 2 O 3 /Nb joint brazed using a 70Cu-30Zn alloy as joining element. Cylindrical Al 2 O 3 disks were produced by sintering of powder at 1550°C and the Al 2 O 3 /Cu-Zn/Nb/Cu-Zn/ Al 2 O 3 arrangements were bonded at 920°C to 980°C in argon atmosphere. Effective bonding of Al 2 O 3 to Nb was observed at 950°C and 980°C, however joining was not possible at 920°C. Scanning electron micrographs of the reaction layer show the growth of the interface zone increasing with both bonding temperature and time. Evidence of Nb diffusion towards the joining element forming spherical Nb-rich precipitates near to the Al 2 O 3 bonding line was evident from the SEM observations. Mechanical characterization of the joints at 980°C showed shear stress results varying from 57 to 127 MPa in samples joined for different times.