Curing with (LN2) liquid nitrogen

Producing aircraft components such as radomes, control surfaces, and body panels from fibre-reinforced polymer composite structures can benefit from the use of liquid nitrogen.

The aircraft part is generally assembled using layers of fibre reinforcing and a resin to glue them together. After the parts are "laid up", they are inserted in an autoclave to cure the system to provide strength and integrity. After the parts are put into the autoclave, heat and nitrogen gas are added. As the temperature causes the resin to cure, the nitrogen at 200–400 psig is introduced to maintain a steady pressure. This is done to hold the laminates in place during the heating and curing cycle as well as to squeeze any air bubbles or excess resin from between the layers of the composite material.

The primary reason for using nitrogen, however, is safety. Nitrogen prevents the formation of combustible or explosive mixtures in the autoclave.