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  • 1
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    Space processing of chalcogenide glasses (1975)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Chalcogenide glasses are discussed as good infrared transmitters, possessing the strength, corrosion resistance, and scale-up potential necessary for large 10.6-micron windows. The disadvantage of earth-produced chalcogenide glasses is shown to be an infrared absorption coefficient which is unacceptably high relative to alkali halides. This coefficient is traced to optical nonhomogeneities resulting from environmental and container contamination. Space processing is considered as a means of improving the infrared transmission quality of chalcogenides and of eliminating the following problems: optical inhomogeneities caused by thermal currents and density fluctuation in the l-g earth environment; contamination from the earth-melting crucible by oxygen and other elements deleterious to infrared transmission; and, heterogeneous nucleation at the earth-melting crucible-glass interface.
    Keywords: ASTRONAUTICS (GENERAL)
    Type: NASA-CR-120745 , AR-1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Unknown
    Space processing of chalcogenide glass (1976)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The manner in which the weightless, containerless nature of in-space processing can be successfully utilized to improve the quality of infrared transmitting chalcogenide glasses was investigated. The following conclusions were reached: (1) Laboratory experiments have established the techniques, processes and equipment necessary for the production of high purity chalcogenide glasses. (2) Processing techniques have been successfully adopted for Ge28Sb12Se60 glass in a 1-g environment. (3) The Ge28Sb12Se60 glasses that have been processed have optical transmission around 63% (5 mm thick). (4) Laboratory experiments have established that the use of precursor materials in powdered form increases the oxygen contamination of the processed glass. This indicates that high purity precursor materials in bar or pellet form should be used. (5) Modifications were made on the MSFC acoustic levitator in an attempt to improve levitation stability during long-time experiments. Room temperature experiments on As2S3 glasses and high temperature experiments on polystyrene were conducted.
    Keywords: ASTRONAUTICS (GENERAL)
    Type: NASA-CR-144278 , ASR-2
    Format: application/pdf
    Location Call Number Expected Availability
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    NASA TECHNICAL REPORTS
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