Thesis
Mechanism and an application of electrically induced liquid metal flow
Washington State University
Master of Science (MS), Washington State University
2010
Handle:
https://hdl.handle.net/2376/103043
Abstract
This work reports on the effect of electric field and electromigration producing controllable range flow of pure liquid metals (Ga, Sn, Bi, Pb, and Al). The flow of atoms due to electromigration in liquid metals was found to be different from that in solid state in two ways: (a) the flow occurs along the applied electric field, which is opposite to solid state electromigration, and (b) the flow-rate was ~104 times larger than observed in solid state. These were attributed to (i) the larger scattering cross-section of atoms in liquid state, and (ii) the higher mobility of liquid atoms due to the low activation energy of self diffusion. It was found that the drift velocity of migrating atoms was proportional to the diffusivity of the liquid metal, the effective charge number of the metal, and the current density in the liquid metal. It was established that the operative mechanism of flow was predominantly electromigration. The phenomenon was henceforth termed "liquid electromigration" (LEM). During observation, pure liquid metal flowed in a smooth, continuous stream that fully coated the conductive substrate on which motion occurred and transitioned to a discontinuous transport regime where stationary beads of metal sequentially grew and shrank after a long flow time. In the discontinuous transport regime, the beads remained stationary and changed size while current was flowing in the liquid while new beads continually nucleated ahead of the previous providing a definitive 'melt front' ahead of which there were no beads. The relationship between substrate surface roughness, apparent wetting angle, and the transition from continuous to discontinuous transport was examined. The form of LEM transport (i.e. continuous or discontinuous) was found to correlate to the apparent wetting angle of the liquid metal. Liquid electromigration can be applied to improve on several existing technologies, for example, reversible metal coating on conductive grids, as well as to engender many new technologies, like contact based nanolithography tools, and micro-/nano-fluidic pumps. The present study reports the application of this technology for metal coating on a linear and a non-linear conductive path as well as the development of a lithography tool.
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Details
- Title
- Mechanism and an application of electrically induced liquid metal flow
- Creators
- Jacob James Howarth
- Contributors
- Indranath Dutta (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525031101842
- Language
- English
- Resource Type
- Thesis