Molten Sand Induced Degradation of Ultra High Temperature Ceramic Diborides
Abstract
The desire for increased performance of gas turbine engines (GTE) is leading to higher operational temperatures within GTEs. Thermal and environmental barrier coatings (T/EBC) applied to turbine blades (typically the hottest component) allow for temperatures to reach as high as 1700 deg C. T/EBCs; however, they are susceptible to deterioration when in contact with liquified atmospheric particulates. These particulates are composed of varying amounts of calcia, magnesia, alumina, and silicates (CMAS). At elevated GTE operating temperatures, the molten CMAS attacks the T/EBC, greatly reducing the performance and lifespan of turbine blades. The goal of this thesis is to examine how three different ceramic compositions withstand CMAS penetration. The ceramics are hafnium diboride (HfB2), zirconium diboride (ZrB2), and a high entropy ceramic diboride (Ta0.20, Zr0.20, Nb0.20, Hf0.20, Ti0.20)B2. The ceramics were exposed to a 1:1 CMAS water slurry then placed in the furnace at 1300 deg C and 1600 deg C for 1 and 10 hours. The samples were then analyzed via scanning electron microscope (SEM) and x-ray diffraction (XRD) to identify CMAS penetration and reaction products. Nano-indentation hardness testing was then performed to evaluate how the CMAS impacted the hardness. All samples experienced CMAS intrusion and oxidation with varying effects on the materials nano-hardness.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2023
- Accession Number
- AD1213698
Entities
People
- Collin L. Vorbroker
Organizations
- Naval Postgraduate School