Takao Nakagawa

Lunar and deep–space exploration and astronomical observation missions equipped with cooling systems for high–sensitivity observations require thermal switches (also called heat switches) that can adjust the heat flow to control the temperature inside spacecraft appropriately. In this study, we proposed a mechanical heat switch utilizing a single–crystal Cu–Al–Mn shape memory alloy for its drive unit. The effect of aging treatment on the martensitic transformation temperature (heat switch drive temperature) of a Cu–17Al–11.6Mn (at.％) alloy was investigated, and it was found that the transformation temperature could be adjusted in the range of −80 to −50°C by varying the duration from 15 min to 2 h at an aging temperature of 150°C. A prototype heat switch was fabricated using a single crystal with an orientation exhibiting a large transformation strain. Cooling–heating tests for the drive unit demonstrated thermal drive with a large displacement of approximately 0.8 mm and a small temperature hysteresis, indicating that the single–crystal Cu–Al–Mn shape memory alloy is highly applicable to heat switches.