The objective of this project was to develop inexpensive structural cryogenic insulation foam that has increased impact resistance for launch and ground-based cryogenic systems. Two parallel approaches were used: a silica-polymer co-foaming technique and a post-foam coating technique. Structures were fabricated using both techniques to formulate insulation for the specified applications. The insulation will survive in space and terrestrial environments, provide a good moisture barrier, and exhibit thermal insulation properties.
The cryogenic insulation was developed to meet NASA's need to reduce fuel losses through boil-off, minimize materials and costs, and increase mission duration for both ground and on-orbit applications. InnoSense LLC's (ISL) organically modified silicate technology was used to formulate cryogenic insulating foams (CryoPore) with superior performance over the baseline polyurethane (PU) foams used by NASA.
Tests demonstrated that aerogel-impregnated polyurethane foams improved the insulative and hydrophobic properties of the baseline (PU) foams. The CryoPore foams also exhibit good flexibility, and are pourable and sprayable. Additionally, it was demonstrated that halogen-free flame retardants can be easily integrated into the foams. The CryoPore foams offer a moldable insulation that is lightweight and can be applied to aluminum tank substrates. Another blowing agent was identified that produces carbon dioxide to further reduce foam density. These primarily closed cell foams reduce the base foam density by about 1/3 for aerogel-impregnated foams, and offer improved insulating capabilities at cryogenic temperatures.
ISL accomplished the following: fine-tuned foam formulations resulting in coherent, low-density foams of closed-cell and fine-cell structure; developed a two-part pourable foam formulation applicable to a variety of substrates; improved the thermal properties of the foam by adding aerogel to the base PU foam; demonstrated that non-halogenated, flame-retardant additives improve flame-retardant properties without hindering foam formation; and conducted tests on the foam samples at cryogenic temperatures (20 K) under vacuum.
The cryogenic insulation will be conformable to almost any shape, and will be usable with cryogenic gases like oxygen, nitrogen, and hydrogen. NASA applications include insulation for earthbound and in-flight cryogenic transfer lines, pumps, storage tanks, and vessels; in-flight fuel tanks; and modular structures. Ground and launch operations currently make up 45-60% of total costs.