Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


29183.pdf (157.68 MB)

ETD Abstract Container

Abstract Header

Development of High Temperature Erosion Tunnel and Tests of Advanced Thermal Barrier Coatings

Shin, Dongyun
http://orcid.org/0000-0001-9235-0902
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1522415020378523

Abstract Details

2018, PhD, University of Cincinnati, Engineering and Applied Science: Aerospace Engineering.
The thermal barrier coating is applied to the surfaces of the metal components of the gas turbine hot section, for example, a combustor liner, vanes, and rotating turbine blades. The coating contributes to increasing the operating temperature by providing a heat shield between the hot gas and the metallic substrate of the gas turbine engines. As well as increasing the service life of the gas turbine engine, the specific fuel consumption can also be improved with the increased overall pressure ratio. In particular, 6-9% wt. Yttria partially stabilized zirconia (7YSZ) ceramic coating has been widely used because of its excellent hardness, good erosion resistance, low thermal conductivity, and thermal expansion coefficient similar to Nickel based super-alloys. However, the experimental erosion resistance study of TBC by solid particle impact has not been extensively carried out within the operating range of the gas turbine. Through presented study, a preliminary design was conducted for the development of a new advanced high-temperature capable erosion test facility. The optimized length of the accelerating tunnel and design parameters were obtained using the combination of analytical and computational analysis. The performance of developed erosion test facility was validated with the predicted data and compared with the existing legacy erosion tunnel at the University of Cincinnati. This dissertation presents an experimental investigation of the effects of microstructures of topcoat of air plasma sprayed 7 wt\% YSZ thermal barrier coatings (APS 7YSZ TBCs) on erosion resistance at high temperature. A combination of air plasma sprayed YSZ TBCs with three different microstructures (porosities of 12.9 +- 0.5%, 19.5 +- 1.2%, and 3.7 +- 0.7%) was tested in the advanced high-temperature erosion test facility under gas turbine operating temperatures. Experiments were conducted to investigate erosion of TBCs over a range of temperatures between 537C and 980C, gas velocities between 122 m/s and 305 m/s, and impingement angles between 20 degrees and 90 degrees. The two types of erodent powders used in the presented study were nominal 27-micrometer white fused Alumina and nominal 15-micrometer A3 test dust. Experimental results have shown a strong association between increased porosity in the topcoat and reduced erosion resistance. The erosion resistance of advanced TBCs developed to withstand temperatures higher than 7YSZ was also investigated in this study. NASA developed low-k YbGd-YSZ TBCs and Gadolinium Zirconated TBCs (GZO) were experimentally studied under the same test conditions as 7YSZ TBCs to identify their erosion resistance. It was found from the research that, the advanced TBCs showed significantly lower erosion resistance than the 7YSZ TBCs because of their low fracture toughness. However, this study also confirmed that the possibility of enhanced erosion resistance of the low-k YbGd-YSZ by introducing an advanced plasma spraying techniques, such as a dense vertical crack micro-structure and multi-layer top-coat systems.
Awatef Hamed, Ph.D. (Committee Chair)
San-Mou Jeng, Ph.D. (Committee Member)
Jongguen Lee, Ph.D. (Committee Member)
Robert W. Bruce, Ph.D. (Committee Member)
183 p.
Aerospace Materials
erosion; gas turbine; TBC; thermal barrier coating; thermal spray

Recommended Citations

Citations

  • Shin, D. (2018). Development of High Temperature Erosion Tunnel and Tests of Advanced Thermal Barrier Coatings [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1522415020378523

    APA Style (7th edition)

  • Shin, Dongyun. Development of High Temperature Erosion Tunnel and Tests of Advanced Thermal Barrier Coatings. 2018. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1522415020378523.

    MLA Style (8th edition)

  • Shin, Dongyun. "Development of High Temperature Erosion Tunnel and Tests of Advanced Thermal Barrier Coatings." Doctoral dissertation, University of Cincinnati, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1522415020378523

    Chicago Manual of Style (17th edition)

ucin1522415020378523
331
© 2018, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.