NEW MEASUREMENT TECHNIQUE FOR THERMAL CONDUCTIVITY OF ABLATIVE MATERIALS

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Abstract
The development of a transient thermal conductivity apparatus specifically for ablative materials is presented. This innovative apparatus is capable of determining thermal conductivity of materials over the temperature range of 340–1200 K, covering the pyrolytic stage of the composite material. The target specifications of the apparatus are the measurement of thermal conductivity in the range of 0.1–5.0 W · m-1 · K-1 using specimen thickness in the range of 7–25 mm. This is achieved by using a new design of a symmetric heater-specimen assembly, creating an adiabatic state along its centerline. The temperature-controlled system is sustained in a closed chamber, capable of introducing specific gases, enabling tests under a wide range of environmental conditions. Comparison of test results with available data of known materials shows good agreement. Testing of different ablative materials reveals similarities and differences associated with specific compositions and processing features. These results can support modeling of ablative materials for various applications such as solid rocket nozzle throat.