TIME-VARYING ABLATIVE-SURFACE RECESSION RATES OF REFRACTORY COMPOSITES.
Rept. for 1 May 65-30 Apr 66,
AEROSPACE CORP EL SEGUNDO CA LAB OPERATIONS
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In plasma arc tunnel materials testing a finite test time is required at each heat flux and enthalpy level for a material to reach a constant surface recession rate. Until this time has elapsed, measured recession rates will be variable and, most important, will not be valid for determination of surface ablation for longer periods of time. This study determined recession stabilization time for graphitic and tungsten materials and hafnium carbide-carbon alloys. A motion picture photographic technique for recession measurement was developed in which the bright image of the plasma stream was eliminated to clearly outline the magnified specimen hot face during test. In spite of the varied thermal diffusivities of the materials, their recession stabilization times were similar at each enthalpy level studied.
- Metallurgy and Metallography