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Why doesn't ceramic melt when hypersonic vehicles re-enter the atmosphere?
The ceramics used in the space shuttle’s Thermal Protection System in the form of silica fibers have a very high melting point. The melting point is higher than the temperature those parts of the shuttles reached.
The space shuttles used ceramics because ceramics have the ability to radiate heat at high temperatures, and they are poor conductors of the heat. Ceramics are used in the Low-Temperature Reusable Surface Insulation Tiles (LRSI) and High-Temperature Reusable Surface Insulation Tiles (HRSI). These tiles combined the thermal properties of ceramics with the structure of Styrofoam, making these tiles almost 90% empty space. This made the tiles light weight, while still protecting the internal structure of the craft at temperatures of 650°C to 1,300°C (1,200°F to 2,300°F)! These materials were perfect for the space shuttles during reentry, because they did not melt! However, there were other materials used on different parts of the space shuttle which got even hotter. Thanks again for the question!
