Low Emittance Coatings For High Temperature Solar Collectors

D. R. McKenzie; N. Savvides; R. C. McPhedran; D. R. Mills

doi:10.1117/12.936316

1 December 1983 Low Emittance Coatings For High Temperature Solar Collectors

D. R. McKenzie, N. Savvides, R. C. McPhedran, D. R. Mills

Proceedings Volume 0428, Optical Materials and Process Technology for Energy Efficiency and Solar Applications; (1983) https://doi.org/10.1117/12.936316
Event: 27th Annual Technical Symposium, 1983, San Diego, United States

Abstract

We discuss the importance of low emittance and temperature stability for solar-selective high-temperature coatings. We show experimentally that high stagnation temperatures can be achieved by reducing the coating emissivity below previously-obtained values. We have investigated amorphous hydrogenated carbon (a-C:H) and silicon-carbon alloy (a-Si_xCi_-x:H) films prepared by magnetically-enhanced glow discharge decomposition. In the latter case, we have prepared alloys from acetylene, ethylene and methane mixed with silane. We have shown by electron microprobe analysis that the atomic C/Si ratio in the film is the same as that in the gas. We show that both the emittance of a-C:H films and their high temperature stability can be enhanced by annealing in vacuum. The film properties change substantially in the first hour of heat treatment at 500°C, before stabilizing after about 24 hours. Thereafter, the properties do not change during a further 300 hours of heat treatment. The heat -stabilized films, when placed on copper substrates and used in non-concentrating systems, have been shown to yield stagnation temperatures up to 459°C in preliminary experiments. The a-Si_xC_1-x :H films investigated have the potential to provide lower emittance coatings than the a-C:H alloys which are currently employed in composite metal-amorphous semiconductor films. The use of silicon/carbon alloys also provides greater flexibility in grading profiles for the composite films, permitting greater control in the trade-off between high solar absorptance and low emissivity.

Citation Download Citation

D. R. McKenzie, N. Savvides, R. C. McPhedran, and D. R. Mills "Low Emittance Coatings For High Temperature Solar Collectors", Proc. SPIE 0428, Optical Materials and Process Technology for Energy Efficiency and Solar Applications, (1 December 1983); https://doi.org/10.1117/12.936316

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available