Date of Graduation

12-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Mechanical Engineering

Advisor/Mentor

Huang, Po-Hao Adam

Committee Member

Gordon, Matthew H.

Second Committee Member

Spearot, Douglas E.

Third Committee Member

Wejinya, Uche C.

Fourth Committee Member

Chen, Linfeng

Keywords

Applied sciences; Corrosion sensors; MEMS; Metal particles

Abstract

This research is to develop a MEMS-based corrosion sensor, which is used for monitoring uniform, galvanic corrosion occurring in infrastructures such as buildings, bridges. The corrosion sensor is made up of the composite of micro/nano metal particles with elastomers. The mechanism of corrosion sensor is based on the mass transport of corrosive species through the sensor matrix. When the metal particles in the matrix corrode, the electrical resistivity of the material increases due to increasing particle resistances or reduction of conducting pathways. The corrosion rate can be monitored by detecting the resistivity change in sensing elements. The life span of the sensor can be ensured due to the barrier effect of polymeric matrix without losing sensor's sensitivity. The mechanism of corrosion sensor relies on the diffusion process, through which diffusive species penetrate into sensor and react with embedded particles to increase its resistivity. The diffusion process couples the chemical reaction which is described according to concentration rate gradient and collision theory with the diffusion which is usually governed by Fick's diffusion theory.

In this research project, three objectives are achieved:

1. Micro-fabrication approach to fabricate corrosion sensor in terms of developed DPPOST techniques

2. Study of the fundamental mechanism of diffusion through the metal particle PDMS polymer composites and diffusion coefficients

3. Characterization of the electric properties of the composites before and after etching oxide layers of metal particles. Two approaches have been posted to investigate the oxide removal: etching first and mixing first.

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