Identifier

etd-06182013-192815

Degree

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

Document Type

Thesis

Abstract

Thermal Barrier Coatings or TBCs when abbreviated are an imperative part of the thermal protection system of expensive equipment and machinery in the automobile and aeronautics industry. They provide protection to expensive alloy materials upto a temperature of 2700° C without expensive metallurgical additions. Unfortunately, the problem of coating adhesion has plagued the TBC field for years, leading to catastrophic failures in critical TBC systems. Efforts to chemically improve bond strength has not been entirely successful, so the only other efficient way to do this would be some kind of mechanical interlocking that occurs at micro/nano scales. This research work deals with the improvement of adhesion in TBC systems by numerical simulation and bench-marking of micro-geometric surface features that has been synthesized or reproduced in laboratory environment through electrochemical operations. For this, several geometries that benefit mechanical interlocking, and consequently improvements in mechanical 'adhesion' in TBCs has been compared. To simulate the mechanical and thermal loading on the micro geometries and to observe their effect, the commercial finite element software COMSOL was used. An analogy was drawn between the biological, Van der Waals dry adhesion mechanism in Gecko feet and that in the top surface of the thermally grown oxide (TGO) layer in TBC whereas the 'mushroom head geometry' in the Gecko feet provides improved adhesion (as much as 10 folds) compared to other geometries (spatular head, spherical head, or plain triangular crevices). An affordable synthesis process, termed “Electrolytic Plasma Processing (EPP)" for recreating this specific geometry, is also proposed and its utility briefly entertained. The work ends with recommendations and suggestions for future works on this topic.

Date

2013

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Wahab, Muhammad A.

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