Accession Number : ADA306032

Title :   Study for Development of Elastomeric Thermal Shield Materials.

Descriptive Note : Contract rept.,

Corporate Author : GENERAL ELECTRIC CO PHILADELPHIA PA

Personal Author(s) : Dolan, C. M.

PDF Url : ADA306032

Report Date : MAR 1965

Pagination or Media Count : 115

Abstract : Work was performed to (a) define, evaluate, and demonstrate new concepts for an easier and more reliable manufacturing process for silicone elastomeric thermal shields, while maintaining high ablation performance and resistance to the general space environment, and (b) define problems and conduct preliminary investigations of materials and methods leading to the development of shape stable elastomers for lifting reentry vehicles. The approaches to achieve an easier manufacturing process included investigation of resin systems, char improving additives, and physical reinforcement approaches. These materials and approaches were evaluated by consideration of manufacturing ease and by critical performance criteria of ability to withstand temperature cycling environment and satisfactory ablation performance. After various screening and evaluation phases, two material systems were selected, properties were generated, a thermostructural analysis made, and a scale-up unit fabricated and thermal cycled. One of the material systems, a foamed phenyl silicone reinforced with aluminum silicate fibers in a discontinuous supporting matrix, met the performance criteria. The second material, a syntactic silicone foam filled with phenolic and silica microspheres in a discontinuous supporting matrix was used in a composite with an underlay of an unsupported foamed phenyl silicone. This formulation met the performance criteria except the extreme low temperature exposure in the scale-up thermal cycle. Modifications of these materials were tested in an ablation environment simulating the reentry conditions of a leading edge and control surface of a typical lifting reentry vehicle. The materials exhibited high heats of ablation combined with minimum shape change to indicate feasibility for this application. In addition, studies were conducted for shield refurbishability, and fastening

Descriptors :   *ELASTOMERS, *HEAT SHIELDS, *LIFTING REENTRY VEHICLES, *THERMAL INSULATION, ABLATION, FIBERS, LOW TEMPERATURE, STABILITY, ALUMINUM COMPOUNDS, ENVIRONMENTS, MANUFACTURING, ATMOSPHERE ENTRY, SPACE ENVIRONMENTS, EXPOSURE(GENERAL), MODIFICATION, PHYSICAL PROPERTIES, SILICON DIOXIDE, MATERIALS, POLYMERS, REACTION TIME, SHAPE, RELIABILITY, RESPONSE, SCALING FACTOR, ADDITIVES, LEADING EDGES, FASTENINGS, THERMAL CYCLING TESTS, SILICATES, PHENOLS, SILICONES, CONTROL SURFACES, FOAM, SYNTACTIC FOAMS, MICROSPHERES.

Subject Categories : Elastomers and Rubber
      Unmanned Spacecraft
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE