Protective coatings and sealants for solar applications
An aging study has been completed which evaluated a number of polymeric materials for potential use as (1) protective coatings for back surfaces of mirrors and (2) solar heliostat edge seals. These investigations were conducted in an artificial weathering chamber that accelerated thermal cycling. The primary mirror failure mode was observed to be silver corrosion resulting from moisture exposure. To increase mirror longevity in current heliostat designs, intimate bonding at all the composite interfaces is essential to minimize moisture pathways to the silvered surface. If any voids or delaminations are present, mirror degradation will eventually occur. Delaminations can also occur as the result of mechanical stresses brought about by mismatches in the various materials coefficients of thermal expansion. If good bonding cannot be achieved or mechanical stresses avoided, then improved moisture barriers must be designed to assure mirror longevity. With good adhesion, a KRATON rubber was found to exhibit superior back surface mirror protection (12 months in environmental chamber with no corrosion). An ultraviolet stabilized butyl rubber appeared to be the best edge seal. All heliostats edge sealed with silicones showed silver corrosion which indicated either poor bonding or moisture permeation.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5139922
- Report Number(s):
- SAND-80-0808
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HELIOSTATS
SEALS
MIRRORS
PROTECTIVE COATINGS
SERVICE LIFE
SOLAR REFLECTORS
AGING
FIBERGLASS
PAPER
PLASTICS
RUBBERS
SILICONES
THERMAL CYCLING
WEATHERING
COATINGS
ELASTOMERS
EQUIPMENT
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
POLYMERS
SILOXANES
SOLAR CONCENTRATORS
SOLAR EQUIPMENT
CSP
Concentrating Solar Power
141000* - Solar Collectors & Concentrators