STUDIES FOR IMPROVED HIGH TEMPERATURE COATINGS FOR SPACE SHUTTLE APPLICATION.

Several concepts for improvement of the current Class 2 Space Shuttle Orbiter RCG coating were investigated experimentally under NASA Contract, NAS2-9809. Coatings, which are applied to LI-900 or LI-2200 tiles were prepared to provide increased performance in the areas of thermal expansion, impact, residual strain and increased viscosity. Turbulent duct arc-plasma tests at NASA/Ames Research Center are continuing on two candidates that show improved low residual strain and increased high temperature viscosity. In the course of this investigation, a coating system with lower fusion-temperature (1950 degree F) was identified. This coating has the potential of significantly improving tile yield through reduced LI-900 shrinkage and distortion since it can be fused at 250 degree F lower than the present Class 2 coating.