Calendar of Events - Event

Event Scheduled for Jul 24, 2015

Event: MSE PhD Dissertation Proposal: Haibo Yu

Location: IMS-159

Time: 02:00 pm

Details of Event:
Ph.D. Dissertation Proposal

Haibo Yu

Microstructural Studies of Ag/W and Ag3Sn/Cu3Sn alloys for Electrical Circuit Breaker Contacts

Friday, July 24th, 2015 2:00 pm


Advisory Committee:
Major Advisor Prof. Mark Aindow
Associate Advisors Prof. S. Pamir Alpay, Prof. Rainer J. Hebert, Prof. Harris L. Marcus, Prof. Avinash M. Dongare.

Contact materials composed of Ag and W have been used in circuit breakers and other electrical switching systems for decades due to their excellent performance. A series of standard acceptance tests have been established by UL (Underwriters Laboratories) to ensure that circuit breakers meet certain criteria for performance and safety. These standard tests include: overload/temperature-rise, endurance and short-circuit conditions. In the dissertation we present a study on the near-surface microstructures exhibited by untested commercial Ag/W circuit breaker contacts and by those that have been subjected to the UL standard tests. The microstructural characteristics were investigated to deduce the degradation mechanisms during each type of test. We also adopt a similar approach to investigate the effects of aging in dry and humid environments on the structure and degradation mechanisms for this type of contacts. The Ag3Sn/Cu3Sn alloy was proposed as a candidate alloy for use of circuit breaker contacts to reduce the cost without compromising the performance. The microstructure characteristics exhibited by the as-cast Ag3Sn/Cu3Sn alloys and by those that have been subjected to standardized UL testing and aging tests will be investigated. The consequences of these observations for the degradation mechanism during testing will be discussed. Some fundamental scientific researches on pure Ag3Sn and Cu3Sn alloys regarding the deformation mechanisms and phase stability will also be conducted.

Sponsored By: Materials Science and Engineering Department

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