Metal/Ceramic Interfaces: Relationships between Structures, Chemistry and Interfaces
Abstract
Interface fracture resistance measurements have been conducted on metal/ceramic interfaces with and without reaction products. Both ductile and brittle interface fracture have been documented. Some effects of residual stress have also been investigated. The influence of thermal expansion misfit on the mechanical behavior of metal/ceramic bonded systems has been shown to be strongly governed by the sign of the misfit strain, its magnitude, the yield strength of the metal and to be subject to substantial geometric effects. In some cases, the misfit causes interface failure, while in other, cracking occurs in the ceramic. Generally, misfit has detrimental effects on bond strength, but in special cases, the bond strength can actually be improved. Reaction products exhibit a wide variety of fracture behaviors. In some cases, the reaction products are brittle and subject to residual stress, leading to low fracture energy interfaces governed by the fracture resistance of the reaction product. In other cases ductile reaction products occur, resulting in good bond properties and fracture energies that increase as the reaction product layer thickness increases. Stress corrosion has been found to occur at oxide/metal interfaces, leading to substantial reductions in the fracture resistance. The phenomenon is governed by water vapor and is similar to, but more pronounced than, that found in oxides.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 15, 1991
- Accession Number
- ADA235713
Entities
People
- A. G. Evans
Organizations
- University of California, Berkeley