Book ; Online: Temperature-Dependent Diffuse Reflectance Measurements of Ceramic Powders in the Near- and Mid-Infrared Spectra
2022
Abstract: This study focuses on experimentally measuring temperature-dependent diffuse reflectance in the near- and mid-infrared spectra for ceramic particles with applications as heat-transfer and thermal-storage media in concentrated solar power (CSP) plants. ... ...
| Abstract | This study focuses on experimentally measuring temperature-dependent diffuse reflectance in the near- and mid-infrared spectra for ceramic particles with applications as heat-transfer and thermal-storage media in concentrated solar power (CSP) plants. Specifically, a commercially available sintered bauxite ceramic powder, ACCUCAST ID80, and its primary chemical constituents, alumina (Al2O3) and silica (SiO2), are measured using a Fourier transform infrared spectrometer (FTIR) coupled with a specialized diffuse reflectance accessory and a heated stage. Room-temperature diffuse reflectance measurements show increased absorption in tests with greater mass fractions of the ceramic samples. There is a strong correlation in the measured reflectance spectra of ACCUCAST with alumina and silica in the spectral range 2000-500 cm-1. For the first time, temperature-dependent diffuse reflectance measurements are reported for ACCUCAST, including a novel technique for accessing reflectance values above the limiting temperature of the background material KBr. All three materials exhibit a calculated emittance of ~0.9 at room temperature. However, this value drops to 0.68 at 1000 C for ACCUCAST and ~0.43 for alumina and silica. Thermal cycling in air from 25 C to 1000 C resulted in a visible color change from dark grey to light orange for ACCUCAST and a subsequent 5X greater increase in reflectance at 4000 cm-1 as compared to ACCUCAST thermally cycled at 1000 C in vacuum. Alumina and silica spectra proved to be largely unaffected by thermal cycling under atmospheric and evacuated conditions. |
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| Keywords | Condensed Matter - Materials Science ; Physics - Instrumentation and Detectors ; Physics - Optics |
| Subject code | 660 |
| Publishing date | 2022-04-13 |
| Publishing country | us |
| Document type | Book ; Online |
| Database | BASE - Bielefeld Academic Search Engine (life sciences selection) |
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