| 摘要 |
<p>A cold heat accumulating material for extremely low temperatures which comprises magnetic cold heat accumulating granular bodies in which a rate of particles, which are destroyed when a compressive force of 5 MPa is applied thereto by a mechanical strength evaluation die, out of the magnetic cold heat accumulating particles constituting the magnetic cold heat accumulating granular bodies is not more than 1 wt.%. In this magnetic cold heat accumulating granular bodies, a rate of magnetic cold heat accumulating particles having more than 1.5 form factor R expressed by L<2>/4 pi A, wherein L represents a circumferential length of a projected image of each magnetic cold heat accumulating particle, and A a real area of the projected image, is not more than 5 %. Such a cold heat accumulating material for extremely low temperatures is capable of providing excellent mechanical properties with respect to mechanical vibration with a high reproducibility. A cold heat accumulator for extremely low temperatures is formed by filling a cold heat accumulating container with a cold heat accumulating material for extremely low temperatures comprising the above-mentioned magnetic cold heat accumulating granular bodies. Such a cold heat accumulator for extremely low temperatures can display excellent refrigerating performance for a long period of time. <IMAGE></p> |
