Identifier

etd-07112014-161623

Degree

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

Document Type

Thesis

Abstract

Microscale molding replication and transient liquid phase (TLP) bonding were used to fabricate Al-based microchannel heat exchangers (MHEs) and micro gas chromatograph (mGC) columns. Metal-based microchannel heat exchangers often experience corrosion as a result of their operating conditions. To address this problem, an internal anodization method was developed in Al microtubes by pulsing the flow of electrolyte through a microtube when the current dropped below a set value. The anodic aluminum oxide (AAO) films were characterized by scanning electron microscopy (SEM), focused ion beam (FIB) cross sections, and X-ray energy dispersive spectroscopy (EDS) to determine their growth rate and morphology. The AAO was sealed by immersing in near-boiling water, and then subjected to a linear sweep voltammetry corrosion test in NaCl, which showed an order of magnitude decrease in the corrosion current between un-anodized and anodized/sealed microtubes. The anodization process was extended to MHEs, and subsequent corrosion testing showed superior resistance to ion diffusion within the AAO film. Al-based mGC columns were fabricated and tested for carrier gas flow rate and single-compound efficiency, then they were subsequently anodized using the same process as the MHEs at 30V or 50V for 3 hours or 8 hours. They were re-tested for single compound efficiency then used to separate an n-C4 through n-C9 hydrocarbon standard. Comparison with a commercial column of the same length showed that the mGC columns had a lower resolution because of lower retention times for all compounds. Additionally, the n-C8 and n-C9 peaks had significant tailing. On the other hand, the mGC columns had higher efficiency than the commercial column for n-C5, n-C6, and n-C7. Characterization via SEM and EDS showed that inconsistent AAO morphology was one likely cause of the lower resolution and tailing. A series of recommendations for manufacturing improvements were provided, including changes to the anodization process and surface treatment of the AAO to lower the distribution of active site energies.

Date

2014

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Meng, Wen Jin

DOI

10.31390/gradschool_theses.3045

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