Toroidal anvils

Figure 5. Different types of opposed-anvil devices (a) Bridgman (b) Drickamer (c) girdle (d) belt (e) sample area of the toroidal anvil.

A diagrammatic plan of the Paris-Edinburgh press is shown in Eig. 2. The press can use a variety of anvil designs, with the toroidal anvils of Khvostantsev [132]... 

Fig. 2 A schematic diagram of the VX3 model of the Paris-Edinburgh (P-E) press. Key (1) Hardened steel main frame (2) Breech (3) Piston (4) Hydraulic fluid inlet (5) Tungsten carbide toroidal-profile anvils with 2° bevel angle (6) Sample chamber. Note the scale...

Fig. 1.17 Toroidal anvils used by Besson et al The sample space (S) has a volume of 100 mm a diameter of 6 mm (W) a flat Cu-Be washer, (T) a toroidal hardened Cu-Be gasket.

In the toroidal-anvil system, the pressure in the sample and gasket assembly is close to a parabolic function of the radial distance, r, to the centre. 

Fig. 3.16 A cross section of the toroidal anvil arrangement used in the Paris-Edinburgh cell (1) sample ( 100 mm ), (2) gaskets (null-scattering Ti-Zr alloy), (3) tungsten-carbide anvils, (4) tungsten-carbide seats, (5) steel binding rings, (6) hole for the incident neutron beam, (7) recess at the back of the anvils to reduce absorption, (a) cadmium plating, (e) transmitted neutron beam, (di, dj) diffracted neutron beams, and (i) incident neutron beam.

The belt-type is a modified piston-cylinder apparams, consisting of a cyhndrical belt with a mngsten carbide toroidal core for a tapered sample cavity (die) and two punches, or anvils, with concave surfaces, as shown in Fig. 7.5. The pressure medium has a cylindrical shape. To prevent outflow of the pressure medium between anvils pyrophylhte gaskets are used. A large scale belt-type apparatus is widely used for the production of diamond and c-BN. 

Two types of high-pressure apparatus are schematically illustrated in Fig. 38. They are the so-called belt-type apparams and the multianvil apparatus, both used in diamond and cBN factories. The belt type is a modified piston-cylinder apparatus. There is also an apparatus called the toroid type, whieh is a modified Bridgman-type anvil apparatus. 

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