Swales Aerospace

Charles J Stouffer

Patrick Bourke

Lawrence H Ryczek

Brian Marland

James M Marder

A cryogenic thermal switch operates based on the principle of differential coefficients of thermal expansion of differing materials. A small gap is either closed or opened, dependant upon the relative dimensions of two pieces of differing materials. As the temperature of the pieces is raised, the piece having the greater coefficient of thermal expansion (C,) increases its dimensions at a greater rate, causing a gap to open up. Conversely, when the temperature of the pieces is lowered, the piece having the greater C,shrinks proportionally faster, thereby closing the gap. The present invention makes use of a reliable flat-faced geometry for the two sides of the gap.

Cryogenic thermal switch employing materials having differing coefficients of thermal expansion

A process of bonding metal parts to one another to form seamless, hollow metal articles, particularly made from beryllium. Tooling is assembled to the parts, prior to hot pressing, to cause pressure to be applied to selective portions of the parts. The parts, assembled together with the tooling, are then subjected to hot isostatic pressing at a temperature of about 1700&deg; F. to 1750&deg; F., and at a pressure of about 2000 psi to 2500 psi, for around 3 hours. The tooling surrounding the metal parts functions to limit the amount of compression of the parts. Articles formed by this process are particularly useful in space flight applications because they are formed of a homogeneous material. Strength of the bond is enhanced because no filler metal is used. The absence of a filler metal also eliminates any thermal stress problems as a result of differences in coefficients of thermal expansion.

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Kensington, MD, United States of America

Charles J Stouffer