Accession Number : ADA305140

Title :   Protective Coatings and Sealants for Solar Applications,

Corporate Author : SANDIA NATIONAL LABS ALBUQUERQUE NM

Personal Author(s) : Wischmann, K. B. ; Gonzales, M. H.

PDF Url : ADA305140

Report Date : SEP 1980

Pagination or Media Count : 47

Abstract : 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. We observed the primary mirror failure mode 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. jg p6

Descriptors :   *MIRRORS, *PROTECTIVE COATINGS, *SEALING COMPOUNDS, *SOLAR SATELLITES, STRESSES, MECHANICAL PROPERTIES, AGING(MATERIALS), CORROSION, DEGRADATION, EXPOSURE(GENERAL), INTERFACES, MATERIALS, POLYMERS, LAMINATES, FAILURE, CYCLES, SURFACES, COEFFICIENTS, THERMAL EXPANSION, HEATING, BARRIERS, MOISTURE, ACCELERATED TESTING, CHAMBERS, SILVER, WEATHERING, BUTYL RUBBER, HELIOSTATS.

Subject Categories : Coatings, Colorants and Finishes
      Astrophysics
      Adhesives, Seals and Binders
      Astronautics

Distribution Statement : APPROVED FOR PUBLIC RELEASE