Joining of alumina via copper/niobium/copper interlayers
- LBNL Library
Alumina has been joined at 1150 degrees C and 1400 degrees C using multilayer copper/niobium/copper interlayers. Four-point bend strengths are sensitive to processing temperature, bonding pressure, and furnace environment (ambient oxygen partial pressure). Under optimum conditions, joints with reproducibly high room temperature strengths (approximately equal 240 plus/minus 20 MPa) can be produced; most failures occur within the ceramic. Joints made with sapphire show that during bonding an initially continuous copper film undergoes a morphological instability, resulting in the formation of isolated copper-rich droplets/particles at the sapphire/interlayer interface, and extensive regions of direct bonding between sapphire and niobium. For optimized alumina bonds, bend tests at 800 degrees C-1100 degrees C indicate significant strength is retained; even at the highest test temperature, ceramic failure is observed. Post-bonding anneals at 1000 degrees C in vacuum or in gettered argon were used to assess joint stability and to probe the effect of ambient oxygen partial pressure on joint characteristics. Annealing in vacuum for up to 200 h causes no significant decrease in room temperature bend strength or change in fracture path. With increasing anneal time in a lower oxygen partial pressure environment, the fracture strength decreases only slightly, but the fracture path shifts from the ceramic to the interface.
- Research Organization:
- Lawrence Berkeley National Lab., CA (US)
- Sponsoring Organization:
- USDOE Director, Office of Science. Office of Basic Energy Studies. Division of Materials Sciences (US)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 775106
- Report Number(s):
- LBNL--45299
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 18-19 Vol. 48; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINA NIOBIUM COPPER CERAMIC JOINING CERAMIC/METAL INTERFACES INTERFACIAL DEWETTING GRAIN BOUNDARY GROOVING FRACTURE ADHESION FRACTURE STRENGTH TEMPERATURE DEPENDENCE OF STRENGTH
ALUMINIUM OXIDES
BONDING
CERAMICS
COPPER
FLEXURAL STRENGTH
FRACTURE PROPERTIES
INTERFACES
NIOBIUM
PARTIAL PRESSURE
SAPPHIRE