Non Destructive Thermal Analysis and In Situ Investigation of Creep Mechanism of Graphite and Ceramic Composites using Phase-sensitive THz Imaging & Nonlinear Resonant Ultrasonic Spectroscopy
- Univ. of Rochester, NY (United States). Inst. of Optics
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Zomega Terahertz Corp., East Greenbush, NY (United States)
In this project, we conducted a comprehensive study on nuclear graphite properties with terahertz (THz) imaging. Graphite samples from Idaho National Laboratory were carefully imaged by continuous wave (CW) THz. The CW THz imaging of graphite shows that the samples from different billet with different fabricating conditions have different pore size and structure. Based on this result, we then used a phase sensitive THz system to study the graphite properties. In this exploration, various graphite were studied. By imaging nuclear graphite samples in reflection mode at nine different incident polarization angles using THz time-domain spectroscopy, we find that different domain distributions and levels of porosity will introduce polarization dependence in THz reflectivity. Sample with higher density is less porous and has a smaller average domain distribution. As a consequence, it is less polarization-dependent and the polarization-dependent frequency is higher. The results also show that samples oxidized at higher temperatures tend to be more polarization dependent. The graphite from the external billet is more polarization dependent compared to that from the center billet. In addition, we performed laser-based ultrasonic measurements on these graphite samples. The denser, unoxidized samples allow surface acoustic waves to propagate more rapidly than in the samples that had already undergone oxidation. Therefore, for the oxidized samples, the denser samples show less polarization-dependence, higher polarization-dependent frequency, and allow the surface acoustic waves propagate faster.
- Research Organization:
- Univ. of Rochester, NY (United States); Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE, Nuclear Energy University Programs (NEUP)
- DOE Contract Number:
- AC07-05ID14517
- OSTI ID:
- 1056847
- Report Number(s):
- DOE/NEUP-09-831; TRN: US1601028
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GRAPHITE
POLARIZATION
CREEP
TEMPERATURE RANGE 0400-1000 K
REFLECTIVITY
SPECTROSCOPY
COMPARATIVE EVALUATIONS
NONLINEAR PROBLEMS
POROUS MATERIALS
SOUND WAVES
WAVE PROPAGATION
VELOCITY
THERMAL ANALYSIS
CERAMICS
DENSITY
OXIDATION
SURFACES
IMAGES
POROSITY
COMPOSITE MATERIALS
THZ RANGE 01-100
ULTRASONIC WAVES