CERAMIC JOINING-III BONDING OF ALUMINA VIA CU NB/CU INTERLAYERS/

A method of ceramic-ceramic joining that exploits a multilayer interla yer designed to form a thin, potentially transient layer of liquid pha se has been used to join alumina to alumina. Microdesigned multilayer Cu/Nb interlayers were used to achieve bonding at 1150-degrees-C. Flex ure strengths of as-bonded samples ranged from 119 to 255 MPa, with an average of almost-equal-to 181 MPa. The ability to form 'strong' cera mic/metal interfaces is also indicated by instances of ceramic failure . Microstructural and chemical characteristics of fracture surfaces we re evaluated using SEM, EDS and microprobe. The impact of post-bonding anneals of 10 h duration at 1000-degrees-C in gettered argon on room- temperature joint strength was assessed. High strengths (198 to 238 MP a) were obtained. The retention of strength following annealing in low oxygen partial pressure argon differs from the behaviour previously o bserved in Cu/Pt bonded alumina. Effects of the anneal on interfacial microstructure were determined, and an explanation for this difference in behaviour is proposed.