A framework for designing interlayers for ceramic-to-metal joints

Engineering ceramics have become widely used as structural materials due to their excellent mechanical and thermal properties at high temperature. In most structural applications, ceramics are integrated as critical components in a system that is largely metallic and have to be joined frequently to metals. During joining processes, residual stresses are induced in the joints due to the large differences in physical properties between ceramics and metals, which degrades the mechanical integrity of the joints. This thesis proposes improved design rules for interlayers used to accommodate residual stresses in ceramic-to-metal joints. Efforts have been made on developing theoretical understanding of the important factors affecting residual stresses. Using Finite Element Method (FEM) simulations and Order of Magnitude Scaling (OMS), our understanding could be summarized and generalized as closed-form analytical equations. In these equations, the accumulated elastic strain energy in the ceramic has been used as a more reliable metric for quantifying residual stresses and predicting failure stress. The equations provide a useful functional relationship between the strain energy, material properties, and joint geometry. To the best of our knowledge, they are the first analytical expressions explaining the plasticity effect in the ceramic-to-metal joints. In these equations, the strain energy normalized by the scaling factor consisting of dominant parameters is a linear function of dimensionless groups of secondary important parameters. The physical implication of each dimensionless group also has been clearly defined. Based on analytical equations, improved interlayer design rules have been proposed and verified experimentally.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Park, Jin-Woo, 1972-

Advisor dc:contributor.advisor

• Thomas W. Eagar.

• Materials Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/29913

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/29913