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High Temperature Damage Characterization Of Ceramic Composites And Protective Coatings

Appleby, Matthew P.
http://orcid.org/0000-0002-9089-3863
http://rave.ohiolink.edu/etdc/view?acc_num=akron1461932405

Abstract Details

2016, Doctor of Philosophy, University of Akron, Mechanical Engineering.
Novel high-temperature experiments were conducted in ordered to address some of the most critical life-limiting issues facing woven melt-infiltrated, silicon carbide (SiC) fiber-reinforced SiC ceramic matrix composites (CMCs) as well as protective thermal and environmental barrier coatings (T/EBC). Heating of specimens was achieved using laser-based approaches that simulate the high heat-flux thermal gradient environments that these materials will be subjected to in service. Specialized non-destructive evaluation (NDE) and inspection techniques were developed to investigate damage modes and material response. First, in order to examine the capabilities of utilizing the emerging technique of electrical resistance (ER) measurement for use in high temperature mechanical testing in SiC/SiC CMCs, the temperature dependent ER response of several systems was determined. A model was developed to establish the contribution to overall ER from the individual composite constituents and applied thermal gradient. Then, elevated temperature tensile tests were performed to characterize the damage of composite materials to localized stress concentrations. Further experiments were done to assess the differences in damage mechanisms and retained tensile strength properties of uncoated SiC/SiC CMCs and EBC-CMC systems after prolonged exposure to high pressure, high velocity water vapor containing environments. Differences in damage modes were described using ER monitoring and post-test inspection. Localized strain fields were measured using a novel digital image correlation (DIC) technique and stress-dependent matrix crack accumulation was monitored using in-situ modal acoustic emission (AE). Coupled AE and thermography measurements were also used to describe failure of protective ceramic coatings due to the life-limiting case of thermal cyclic loading. Due to the complex nature of T/EBC failure, the decrease in coating life and durability due to thermal stress concentrations and degradation via molten calcium-magnesium-aluminosilicate (CMAS) infiltration was also examined. Finally, the use of ER measurements for damage characterization was extended to the complex case of creep and stress-rupture of damaged and undamaged composites as well as the dramatic increase in stress-rupture life to SiC/SiC CMCs from environmental barrier coatings. Post-test microscopy was performed to further explain differences in material response and damage morphology.
Gregory Morscher (Advisor)
Manigandan Kannan (Committee Member)
Kwek Tze Tan (Committee Member)
Craig Menzemer (Committee Member)
Alper Buldum (Committee Member)
224 p.
Mechanical Engineering
ceramic matrix composites; environmental barrier coatings, thermal barrier coatings; non-destructive evaluation; electrical resistance; acoustic emission; digital image correlation

Recommended Citations

Citations

  • Appleby, M. P. (2016). High Temperature Damage Characterization Of Ceramic Composites And Protective Coatings [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1461932405

    APA Style (7th edition)

  • Appleby, Matthew. High Temperature Damage Characterization Of Ceramic Composites And Protective Coatings. 2016. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1461932405.

    MLA Style (8th edition)

  • Appleby, Matthew. "High Temperature Damage Characterization Of Ceramic Composites And Protective Coatings." Doctoral dissertation, University of Akron, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1461932405

    Chicago Manual of Style (17th edition)

akron1461932405
2,645
© 2016, some rights reserved.Creative Commons License High Temperature Damage Characterization Of Ceramic Composites And Protective Coatings by Matthew P. Appleby is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Akron and OhioLINK.