Thermal Imaging to Characterize Performance of Space Grade Ablative Silicones

For decades Dow Silicones has been developing silicone solutions for aerospace, defense, and avionics. Silicone ablative coatings are a part of DOWSIL™ materials family and have been designed to prevent direct flame contact with underlying surfaces and protect rocket launch infrastructure and deployment devices, as well as aircraft engines, from extreme temperatures and oxygen attack. During launch, the rocket exterior is subjected to extreme temperatures over 1500 ^oC in seconds, chemical exposure to fuel and intense vibration during takeoff. Silicone ablatives are easy to apply and offer superior performance under high shear, high heat flux environments, toughness, low thermal conductivity, and extended operation temperature range. The ablative coatings dissipate heat through thermochemical degradation. Slow release of pyrolysis gases creates a cooling effect within the material. The goal of this work was to demonstrate the performance of these formulations at close-to-reality thermal conditions. A custom imaging solution was designed to record heating and cooling behavior of a subset of application-tailored ablative coatings. In the experiments the coatings were applied to ceramic tiles and subjected to extreme temperatures for up to 30 seconds. The heating and cooling events were recorded with a high-resolution scientific long-wave infrared camera coupled with a machine vision camera. The details of the experimental set up, time-temperature profiles of the coated substrates, and thermal and digital images of the ablatives will be reported.