Study of Low Temperature Materials (1)

Thermal and Mechanical Properties of Structural Support Materials at Cryogenic Temperatures

Abstract

In designing a cryogenic storage system with low heat leak, a cautions consideration must be paid on the selection of a support structure and materials connecting the inner vessel with the outer vessel. In view of the structural and thermal requirements on a cryogenic storage system, support materials must exhibit high tensile yield strength accompanied by low thermal conductivity, and these properties must be retained even at cryogenic temperatures. From these points of view, measurements were carried out on mechanical and thermal properties of candidate materials for cryogenic structural support down to liquid helium temperature. The experimental results show that in metallic materials, Titanium Alloys displayed a large ratio of tensile yield strength to thermal conductivity. On the other hand, non metallic materials such as glass- or carbon-fiber reinforced plastics (GFRP, CFRP) exhibited higher strength/conductivity ratios than metallic materials. One particular result is that CFRP showed the extra low thermal conductivity in the temperature range 77K to 4.2K. On the contrary, in the temperature over 77K, GFRP showed lower thermal conductivity than CFRP. Thus, the combined use of GFRP and CFRP will be recommended for cryogenic structural support system.