Accession Number:

ADA235713

Title:

Metal/Ceramic Interfaces: Relationships between Structures, Chemistry and Interfaces

Descriptive Note:

Annual rept. 15 Mar 1989-15 Mar 1991

Corporate Author:

CALIFORNIA UNIV BERKELEY COLL OF ENGINEERING

Personal Author(s):

Report Date:

1991-03-15

Pagination or Media Count:

135.0

Abstract:

Interface fracture resistance measurements have been conducted on metalceramic 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 metalceramic 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 oxidemetal 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.

Subject Categories:

  • Laminates and Composite Materials

Distribution Statement:

APPROVED FOR PUBLIC RELEASE