Multilayer Impregnated Fibrous Thermal Insulation Tiles

Temperature rises are limited by transpiration cooling.

The term “secondary polymer layered impregnated tile” (“SPLIT”) denotes a type of ablative composite-material thermal- insulation tiles having engineered, spatially non-uniform compositions. The term “secondary” refers to the fact that each tile contains at least two polymer layers wherein endothermic reactions absorb considerable amounts of heat, thereby helping to prevent overheating of an underlying structure. These tiles were invented to afford lighter-weight alternatives to the reusable thermal-insulation materials heretofore variously used or considered for use in protecting the space shuttles and other spacecraft from intense atmospheric- entry heating. Tiles of this type could also be useful on Earth as relatively lightweight components of fire-retardant structures.

A Pulse of Heat was applied, by an arc jet in a partial vacuum, to the front surface of a 2.73-cm-thick specimen impregnated with a silicone in the front layer and poly (methyl methacrylate) in the back layer. The rear- surface temperature rise, measured by use of thermocouples, was limited to a range that would be safe for an underlying aluminum structure or for most composite-material structures.