Infrared transmittance of borosilicate based fiber insulations
Review articleOpen access
1989/09/01 Full-length article DOI: 10.1016/0165-1633(89)90028-2
Journal: Solar Energy Materials
AbstractCollimated transmittance spectra for boroxide alkali-silicate glass wool with different fiber diameter distributions are reported. Three distinct maxima at 1520, 1300 and 600 cm−1 were observed. Using a normalizing procedure it is demonstrated that the peaks at 1520 and 600 cm−1 decrease with increasing average fiber diameter. The transmittance maximum at 1300 cm−1 shows a much weaker fiber size dependence which is explained by the refractive index of the fiber material n being close to 1 at that wavenumber, thus greatly reducing the refractive losses. Comparison with bulk glass data and model calculations shows that the collimated transmittance at this wavenumber is enhanced by reduction of the extinction coefficient of the fiber material presumably caused by the rapid quenching of the glass.
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