Cracking mechanisms in Ag-SnO/sub 2/ contact materials and their role in the erosion process

Author

Kang, Shinhoo ; Brecher, Charles

Author_Institution

GTE Lab. Inc., Waltham, MA, USA

Volume

12

Issue

1

fYear

1989

fDate

3/1/1989 12:00:00 AM

Firstpage

32

Lastpage

38

Abstract

An investigation has been conducted into the factors governing the erosion of Ag-SnO/sub 2/ electric contact materials by repeated electric arcing, and the manner in which these factors are altered by chemical effects. Two features found to have major influence were the inhomogeneous interfaces between the Ag matrix and the SnO/sub 2/ granules, and the wetting characteristics of the surface. The Ag-SnO/sub 2/ interfaces, which serve as paths for crack propagation, appear to be the dominant influence during the earlier stages of erosion, while the extent of surface wetting by molten silver, which was found capable of altering the stress intensity at the crack tip, predominates in the later stages. The effect of dopant additives in altering the surface activity was also examined.<>

Keywords

arcs (electric); electrical contacts; materials testing; silver; thermal stress cracking; tin compounds; Ag matrix; Ag-SnO/sub 2/ contact materials; Ag-SnO/sub 2/ interfaces; SnO/sub 2/ granules; arc erosion; chemical effects; crack propagation; crack tip; cracking mechanism; dopant additives; erosion process; inhomogeneous interfaces; repeated electric arcing; stress intensity; surface activity; wetting characteristics; Additives; Chemical processes; Conducting materials; Contacts; Mechanical factors; Silver; Stress; Surface cracks; Testing;

fLanguage

English

Journal_Title

Components, Hybrids, and Manufacturing Technology, IEEE Transactions on

Publisher

ieee

ISSN

0148-6411

Type

jour

DOI

10.1109/33.19009

Filename

19009