Abstract

A technique using evaporated Al coated with double layers of Al₂O₃ and silicon oxide to produce surface films having low solar absorptivity (α) and high total normal and hemispherical emissivities (∊_N and ∊) is described. High vacuum evaporation with an electron gun was used for preparing undecomposed films of Al₂O₃ and SiO₂. α and ∊_N were determined from reflectance measurements made in the wavelength region from 0.2 μ, to 50 μ. ∊ was measured calorimetrically by a transient thermal method. α of all Al + Al₂O₃ + silicon oxide film combinations was determined to be about 0.12. The greatest increase in ∊_N and ∊ was obtained when Al was first coated with Al₂O₃ about λ/4 thick at 10 μ and then overcoated with 2000 Å to 4000 Å of silicon oxide. With such film combinations α/∊ values of less than 0.2 could be readily achieved. Surface films of this type were found to be extremely stable during simulated solar uv irradiation.

© 1971 Optical Society of America

Solar Absorptivity and Thermal Emissivity of Aluminum Coated with Silicon Oxide Films Prepared by Evaporation of Silicon Monoxide

A. P. Bradford, G. Hass, J. B. Heaney, and J. J. Triolo
Appl. Opt. 9(2) 339-344 (1970)

Reflectance, Solar Absorptivity, and Thermal Emissivity of SiO₂-Coated Aluminum

G. Hass, J. B. Ramsey, J. B. Heaney, and J. J. Triolo
Appl. Opt. 8(2) 275-281 (1969)

Reflectance and durability of Ag mirrors coated with thin layers of Al₂O₃ plus reactively deposited silicon oxide

G. Hass, J. B. Heaney, H. Herzig, J. F. Osantowski, and J. J. Triolo
Appl. Opt. 14(11) 2639-2644 (1975)

Reflectance and preparation of front-surface mirrors for use at various angles of incidence from the ultraviolet to the far infrared

Georg Hass
J. Opt. Soc. Am. 72(1) 27-39 (1982)

Increasing the Far-Ultraviolet Reflectance of Silicon-Oxide-Protected Aluminum Mirrors by Ultraviolet Irradiation*

Alan P. Bradford and Georg Hass
J. Opt. Soc. Am. 53(9) 1096-1100 (1963)