Ceramic Springs

Hypersonic aircraft, especially reusable hypersonic aircraft, require advancements in high temperature materials because of the extreme temperatures resulting from frictional heating. One aspect of this problem is making seals that can function through a very large temperature range, perhaps up to 1000 °C or higher. Metallic springs essentially lose their ability to function at 600 °C or below. Silicon nitride compression springs have previously been evaluated by NASA and have been found to be capable of functioning throughout that temperature range, but lack the strength required for most applications. They undergo very limited deformation before failure. TDA will improve the feedstocks and modify the existing process for manufacturing ceramic springs. Through improvements to the grain structure, the resulting springs will overcome their previous limitations.

Ceramic compression springs are being developed so that scramjet engines’ high temperature seals can be preloaded. However, the high temperature – capable springs could also solve problems in the control surface and/or leading edge thermal protection system. These needs are particularly acute for re-usable hypersonic transports, including the descendants for the National Aerospace Plane. High-temperature springs with sufficient strength could also potentially be used to create a seal between the heat and the back shell of (re-)entry vehicles.

Many uses exist outside of NASA, including certain (single-use) air-breathing hypersonic weapon systems; the chemical resistance and high temperature stability of ceramic springs will allow new sealing options in many high-temperature industrial processes. Ceramic springs allowing seals between smaller, simpler pieces of tooling can cut costs by obviating the need for larger, more complex tooling.

This is early/mid-stage (TRL 5) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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