Effects of processing conditions and ambient environment on the microstructure and fracture strength of copper/niobium/copper interlayer joints for alumina
- Univ. of California, Berkeley, CA (United States); LBNL Library
Partial transient liquid phase (PTLP) bonding is a technique which can be used to join ceramics with metals and is used to form niobium-based joints for alumina. The principal advantage to PTLP bonding is that it enables refractory joints to be fabricated at temperatures below those typically required by solid state diffusion bonding. A thorough review of the important parameters (chemical compatibility, thermal expansion match, sufficient wettability of the liquid phase on the solid phases) in choosing a joining material for ceramics by the PTLP method is provided. As in conventional PTLP joining, the current study uses thin (=3 μm) copper layers sandwiched between the alumina (bulk) and niobium (127 μm). However, unlike the case of copper/nickel/copper obium is limited. Consequently, the copper is not entirely dissolved in the process, resulting in a two phase (copper-rich and niobium-rich phases) microstructure. Different processing conditions (temperature and applied load) result in different morphologies of the copper-rich and niobium-rich phases at the interface. These different microstructures exhibit distinct strength characteristics. Extended annealing of as-processed joints can influence the strengths differently depending on the ambient partial oxygen pressure at the annealing temperature. The focus of this work is to correlate processing conditions, microstructure, and resulting joint strength. Under optimum processing conditions (1400°C, 2.2 MPa), joints with strengths in excess of 200 MPa at 1200°C are fabricated.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 843055
- Report Number(s):
- LBNL--47199
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANNEALING
BONDING
CERAMICS
COMPATIBILITY
COPPER
DIFFUSION
FRACTURE PROPERTIES
MICROSTRUCTURE
NIOBIUM
OXYGEN
PROCESSING
THERMAL EXPANSION
TRANSIENTS
WETTABILITY
alumina ceramic
joining copper niobium copper interlayers
joining transient liquid phase
metal ceramic interfaces
wetting interfacial dewetting