Ablative Materials for High Heat Loads. Part I. Environmental Simulation and Materials Characterization.

摘要

Ablative plastic composite materials were investigated and developedfor long time heating environments. The desirable materials performancegoals were high erosive resistance, insulative ability, spallation orother thermomechanical effects. Carbon cloth reinforced phenolic resinand silica cloth reinforced phenolic resin heat shield materials haveacceptable thermochemical ablative surface patterns, erosive rates, andinternal temperatures, but these heat shield materials are relativelyheavy. The multilayer concept was examined with the objective ofdetermining if such constructions could perform comparably withappropriate weight savings. Low density quartz (LDQ) was an effectiveinsulative layer, when bonded between the heat shield and metallicsubstrates. The LDQ consisted of phenolic impregnated silica strands,which alternated at right angles to yield a square wall, non-lacedconstruction. The environment to which the specimens were subjectedwas generated by a five megawatt arc heater which was operatedstepwise for 300 seconds. The ablative response to high heat loadswas found to be dependent upon material composition and construction.Asymmetrical erosion, excessive erosion, or high internal temperatureswere found for six of the candidate composites. (Author, modified-PL)