RARE EARTH OXYSULFIDE CERAMIC COLD STORAGE MATERIAL, ITS MANUFACTURING PROCESS, AND CRYOGENIC COLD ACCUMULATOR USING THE COLD STORAGE MATERIAL

PROBLEM TO BE SOLVED: To provide a rare earth oxysulfide ceramic cold storage material that gives (1) an improved high pressure He gas permeability and a reduced pressure loss, (2)fully withstands the vibration or impact caused by the reciprocal motion of the operating medium such as high pressure He gas and the like or the fluid dynamical stress caused by the high pressure He gas passing through the inside of a cold storage accumulator and (3) maintains an excellent refrigeration capacity in the cryogenic region for a long period of time for improving the refrigeration capacity of a refrigerator. SOLUTION: The cold storage material is composed of porous bodies as the constituent grains in which primary grains made up of crystal grains of a rare earth oxysulfide such as Gd2O2are sintered at the neck. To obtain the constituent grains, a grainy rare earth oxysulfide is HIP-fired at 1,150-1,350°C. The relatively low temperature HIP-firing controls the growth of the primary grains and the densification of the constituent grains, which favorably grows the necks among the primary grains. The ceramic cold storage material is obtained with which the destruction of the constituent grains and the occurrence of fine powders are reduced during the operation of a refrigerator and the refrigeration capacity is increased. COPYRIGHT: (C)2004,JPO