Improvements in plunger dies

摘要

A very high pressure apparatus comprising a core ring and dies co-operating therewith to form a cylindrical cavity, at least one of said dies being movable, is characterized by the provision of a metal collar surrounding the protruding portion of the movable die located so as to be compressed between said core ring and the pressure member of a press which bears upon the movable die. The pressure member and the movable die may be integral. As shown in Fig. 1, separate dies 22 form with a ring 14 buttressed by further rings 16, 18 and 20, a pressure chamber 12. The dies are inwardly urged by pressure members or anvils 36 attached to the platens of a hydraulic press and supported by a collar comprising an outer metal part 28 and an inner portion 32 of a material such as lead having low shear strength and insignificant compressibility. A pyrophyllite body 64 serves to surround the sample cavity and under stress is extruded to a limited extent into the gaps between the parts of the apparatus. Electrical insulation, e.g. of mica may be provided and a layer of metal may be introduced as shown between the rear faces of the dies 22 and the anvils 36. Fig. 2 shows an alternative construction in which the dies are integral with the anvils and the collars comprise rings 58 of high tensile steel. Linings 60 e.g. of lead are provided between the collars and the dies. Fig. 3 shows an arrangement for heating a specimen: within the body 44 (Fig. 2) or 64 (Fig. 1) is a conductive tube 70 e.g. of graphite insulated from the specimen by inner tube 68. Current is applied from the tip of the die 48 to a conductive pad 72 which is insulated from the specimen by disc 74. A corresponding arrangement is provided at the lower end of the tubes 68, 70.