Accession Number : ADA309567

Title :   Experimental and Theoretical Investigation of the Ablative Performance of Five Phenolic-Nylon-Based Materials.

Descriptive Note : Technical note,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER

Personal Author(s) : McLain, Allen G. ; Sutton, Kenneth ; Walberg, Gerald D.

PDF Url : ADA309567

Report Date : APR 1968

Pagination or Media Count : 35

Abstract : Five composite ablation materials which contain various percentages of phenolic resin, powdered nylon, and silica (either as spheres or fibers) have been tested in the Langley 20-inch hypersonic arc-heated tunnel. The tests were carried out in air at a stream stagnation enthalpy of 4800 Btu/lbm (11.16 MJ/kg), a cold-wall aerodynamic heating rate of 119 Btu/sq ft-sec (1.35 MW/sq m), a stagnation pressure on the model surface of 0.066 atmosphere, and a free-stream Mach number of approximately 5. The data obtained from these tests have been used to evaluate the ablative performance of each of the materials and have been compared with theoretical predictions of char-recession rate and (for two of the materials) thermal response. During the tests, char removal was due primarily to oxidation and the char-recession rates were not significantly affected by either mechanical failure or SiO2-C reactions. The addition of 12.5 percent (by weight) SiO2 to the high-density materials produced a significant increase in both char integrity and char-virgin material interface strength but resulted in a decrease (approximately 20 percent) in thermal effectiveness. Reasonable agreement between measured and calculated char-recession rates was obtained by assuming chemical equilibrium at the char surface between the pyrolysis gases, the char, and the test stream, with CO as the primary reaction product. Reasonable agreement between measured and calculated thermal response could be obtained only when the char thermal conductivity was assumed to be approximately 1/3 of its measured value.

Descriptors :   *SILICON DIOXIDE, *COMPOSITE MATERIALS, *NYLON, *ABLATIVE MATERIALS, *PHENOLIC PLASTICS, TEST AND EVALUATION, THERMAL PROPERTIES, REMOVAL, POWDERS, SPHERES, GASES, SURFACES, OXIDATION, THERMAL CONDUCTIVITY, HIGH DENSITY, MACH NUMBER, FAILURE(MECHANICS), FREE STREAM, ENTHALPY, CHEMICAL EQUILIBRIUM, HYPERSONIC WIND TUNNELS, STAGNATION PRESSURE, PYROLYSIS, STREAMS, HYPERSONIC FLOW, CHARRING, ARC HEATING.

Subject Categories : Laminates and Composite Materials
      Inorganic Chemistry
      Organic Chemistry
      Plastics
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE