GB924840A - Improvements in plunger dies - Google Patents

Abstract

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 <PICT:0924840/III/1> <PICT:0924840/III/2> <PICT:0924840/III/3> 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.