Date of Award

12-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

Committee Member

Dr. Rodrigo Martinez-Duarte, Committee Chair

Committee Member

Dr. Joshua B. Bostwick

Committee Member

Dr. Phanindra Tallapragada

Abstract

Heat treatment is a vital step in various disciplines of research and fabrication. As the level of detail to which materials are scrutinized increase, so does our understanding of their sensitivity to temperature. Many processes rely on precise temperature control so that the end products exhibit properties such as crystallinity, purity and material composition in the desired range. The presence of temperature variations during thermal treatment may vary the quality of the product. In this thesis, the possibility of creating temperature differences on a specimen undergoing thermal treatment in a horizontal tube furnace under vacuum is explored. In a furnace system where heat transfer occurs due to both conduction and radiation, it is hypothesized that geometric, conductive or radiative parameters selected to discourage heat flow could increase the magnitude of temperature differences on the heated specimen. Using the help of computerized finite element simulations of a tube furnace model undergoing a heating experiment, the role of these parameters, and ultimately the role of conduction and radiation, in exacerbating or ameliorating these temperature differences are assessed. It was found that impeding uniform heat flow to the specimen causes higher temperature differences on it. This is shown through the analysis of individual parameters such as conductivity and emissivity of the objects inside the furnace, the rate of heating, and the geometry of the heated sample. Wherever a design function restricted heat flow to the specimen’s surface or through its volume, the transient thermal analysis of the process indicated the occurrence of higher magnitudes of temperature difference, giving merit to the hypothesis.

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