3D Hyperpure Silica-Silica Testing

  • T. L. Hackett
  • E. L. Rusert


High purity (hyperpure silica <10 ppm and Astroquartz <500 ppm) three dimensionally woven silica-silica composite materials were evaluated for potential use as a tough reflective heat shield for planetary entry probes. A special weave design was selected to minimize light piping effects through the heat shield thickness. Various Y-yarn weave spacings (0.15, 0.23 and 0.32 cm) were evaluated. Densification efficiency was determined with an 0.7 pm particle size high purity silica binder (1 ppm total metallic impurities) as an initial screening operation. The 0.23 cm Y-yarn spacing was selected as the optimum spacing. Spectral hemispherical reflectance was measured from 0.2 to 2.5 microns at room temperature. Reflectance of three dimensional hyperpure silica-silica composite (0.23 cm Y-7arn spacing) was higher than reflectance of three dimensional Astroquartz silica-silica composite at all three Y-yarn spacings and at all wavelengths measured. Mechanical properties were measured in beam flexure. Because of a lower specific gravity (1.3 to 1.4), the strength results were lower than the slip cast hyperpure fused silica (1.6 gm/cc) evaluated under NASA CR152118. Thermal conductivity of the hyperpure silica-silica composite was measured from room temperature to 908°C. With improved densification techniques a viable Jupiter atmospheric entry probe heat shield could be fabricated from 3D woven silica-silica materials. The lower density material evaluated had very promising reflectance characteristics and improved toughness but the strength did not meet the design requirements.


Heat Shield Fiber Spacing Silica Composite Auxiliary Heater Light Piping 
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  1. 1.
    Nachtsheim, P. R., Peterson, D. L., and Howe, J. T., “Reflecting Ablative Heat Shields for Radiative Environments,” American Astronautical Society, the 17th Annual Meeting, 28–30 June 1971.Google Scholar
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    Blome, J. C., Drennan, D. N., Schmitt, R. J., “High Purity Silica Reflective Heat Shield Development,” NASA CR-137617, MDC E1139, October 1974.Google Scholar
  3. 3.
    Rusert, E. L., Drennan, D. N., and Biggs, M. S. Development, Fabrication and Test of a High Purity Silica Heat Shield,“ NASA CR-152117, April 1978.Google Scholar

Copyright information

© Purdue Research Foundation 1983

Authors and Affiliations

  • T. L. Hackett
    • 1
  • E. L. Rusert
    • 1
  1. 1.McDonnell Douglas Astronautics Company - St. LouisSt. LouisUSA

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