Accurate glass forming for high-temperature solar applications. Final report
Development work was undertaken to thermally form glass for solar concentrators. Sagging and pressing glass to parabolic shapes was investigated with goal of achieving slope errors less than 2.0 mr RMS and costs of $1.25/ft/sup 2/. In addition, a laminating process was investigated to overcome the problem of silvering of a curved surface and to reduce corrosion of the silver. Thermal sagging is a process in which glass is shaped by heating the glass until it is sufficiently soft to deform under its own weight and conform to a mold. For cylindrical parabolic shapes, a method for producing low cost high accuracy molds was developed using castable ceramics and a grinder. Thermal conditions were established for a commercial glass bending furnace to obtain good replication of the mold. The accuracy and cost goals were met for glass size up to 30 x 30 x 0.125 inches and for low iron and regular iron float and sheet glasses. Lamination of two curved pieces of glass using automotive technology was investigated. A silver film was placed between two layers of polyvinyl and butyral (PVB) and this was used to bond two sheets of glass. Economically, and technically, the process appears feasible. However, the non-uniform thickness of PBV cause distortion in the reflected image. More work is needed to assess accuracy of curved laminated composites. Thermal pressing of glass is accomplished by heating the glass until it is soft and mechanically stamping the shape. Equipment was built and operated to determine important parameters in pressing. Control of thermal stresses in the glass is critical to preventing cracks. No glass pieces were produced without cracks.
- Research Organization:
- Suntec Systems, Inc., St. Paul, MN (USA)
- DOE Contract Number:
- AC01-79ET21008
- OSTI ID:
- 5139743
- Report Number(s):
- DOE/ET/21008-T1; ON: DE82014091
- Resource Relation:
- Other Information: Portions of document are illegible
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
GLASS
MATERIALS WORKING
ACCURACY
COST
DEFORMATION
IMAGES
LAYERS
MOLDING
PARABOLIC TROUGH REFLECTORS
POLYVINYLS
PRESSING
SHEETS
SILVER
WEIGHT
ELEMENTS
EQUIPMENT
FABRICATION
METALS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PARABOLIC REFLECTORS
POLYMERS
SOLAR CONCENTRATORS
SOLAR EQUIPMENT
SOLAR REFLECTORS
TRANSITION ELEMENTS
141000* - Solar Collectors & Concentrators
360601 - Other Materials- Preparation & Manufacture