Type
Text
Type
Dissertation
Advisor
Sampath, Sanjay | Herman, Herbert | Johnson, Curt | Nakamura, Toshio.
Date
2015-12-01
Keywords
Materials Science | Coating, Fatigue, Thermal Spray
Department
Department of Materials Science and Engineering.
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/76350
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
Thermal Spray (TS) coatings have seen extensive application as protective surfaces to enhance the service life of substrates prone to damage in their operating environment (wear, corrosion, heat etc.). With the advent of high velocity TS processes, the ability to deposit highly dense (>99%) metallic and cermet coatings has further enhanced the protective ability of these coatings. In addition to surface functionality, the influence of the coating application on the mechanical performance of a coated component is of great concern when such a component will experience either static or cyclic loading during service. Using a process mapping methodology, the processing-property interplay between coating materials meant to provide damage tolerant surface or for structural restoration are explored in terms of relevant mechanical properties. Most importantly, the residual stresses inherent in TS deposited coatings are shown to play a significant role in the integrated mechanical performance of these coatings. Unique to high velocity TS processes is the ability to produce compressive stresses within the deposit from the cold working induced by the high kinetic energy particles upon impact. The extent of these formation stresses are explored with different coating materials, as well as processing influence. The ability of dense TS coatings to carry significant structural load and synergistically strengthen coated tensile specimens is demonstrated as a function of coating material, processing, and thickness. The sharing of load between the substrate and otherwise brittle coating enables higher loads before yield for the bi-material specimens, offering a methodology to improve the tensile performance of coated components for structural repair or multi-functionality (surface and structure). The concern of cyclic fatigue damage in coated components is explored, since the majority of service application are designed for loading to be well below the yield point. The role of coating properties and residual stress, processing effects, and substrate choice on the changes in specimen fatigue life is explored, with a mechanism for failure postulated. | 230 pages
Recommended Citation
Vackel, Andrew, "Structurally Integrated, Damage Tolerant Thermal Spray Coatings: Processing Effects on Surface and System Functionalities" (2015). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 2274.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/2274