ORCID

0009-0001-1423-441X

Keywords

Yttria-stabilized zirconia, Si(B)CN, Boron nitride nanotube, Ceramic Matrix Composites, Hydrogen Combustion, Thermal Stability

Subject Categories

Ceramic Materials | Materials Science and Engineering | Mechanical Engineering

Abstract

The growing demand for carbon-neutral energy conversion has accelerated the development of hydrogen-fueled gas turbine systems, which operate at significantly higher temperatures and more chemically aggressive environments than conventional natural gas turbines. To meet these stringent requirements, ceramic matrix composite (CMC) materials consisting of yttria-stabilized zirconia (YSZ) fiber reinforced Si(B)CN ceramic matrix were developed. To further enhance in-plane heat dissipation, thermal stability, thermal shock resistance, and thermal cycling performance, a Si(B)CN/Boron Nitride Nanotubes (BNNT) nanocomposite coating was incorporated onto the YSZ/Si(B)CN composites. Microstructural characterization confirmed the formation of a continuous Si(B)CN ceramic matrix reinforced with uniformly distributed BNNTs. The resulting YSZ/Si(B)CN composites coated with BNNT/Si(B)CN exhibited excellent thermal stability and thermal cycling performance. During hydrogen torch testing at temperatures exceeding 1,400 °C for 45 min, the composite maintained structural integrity while exhibiting a temperature gradient greater than around 840 °C between the front and back surfaces, demonstrating outstanding thermal insulation performance. In thermal cycling tests, the composites were repeatedly heated from room temperature to 1,400 °C–1,500 °C, held for 10 min, and cooled to room temperature. The composites remained intact after multiple cycles without damage. At elevated temperatures, the BNNT/Si(B)CN coating formed a viscous molten phase that infiltrated cracks and gaps between YSZ fibers. Upon cooling, this phase solidified and helped mitigate thermal stresses, thereby enhancing thermal cycling durability. Furthermore, the interconnected BNNT network provides load transfer pathways and suppresses shrinkage-induced cracking during pyrolysis. This study demonstrates an effective strategy for reinforcing polymer-derived Si(B)CN ceramics with BNNT networks to achieve directional heat dissipation and superior thermal durability. The developed composite system shows a strong potential for thermal management and structural protection in extreme hydrogen combustion environments and offers a promising material solution for next-generation hydrogen-fueled gas turbine components.

Completion Date

2026

Semester

Summer

Committee Chair

Gou, Jihua

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Department of Mechanical and Aerospace Engineering

Format

PDF

Document Type

Dissertation

Language

English

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