Notes on Compressible Gasket and Bridgman-Anvil Type High Pressure Apparatus

The squeezing process of a disc-shaped gasket, which is compressed between Bridgman anvils, is analyzed by a simple model. It is made clear that plastic flow and pressure distribution in the disc is governed by its thickness. A normalized characteristic thickness, which can be determined for each disc material by thickness measurement on squeezed discs, is defined and correlated experimentally with shear strength of the material under pressure. According to the correlation, a simple method is developed to evaluate substances for solid pressure materials. A Bridgman anvil apparatus and sample assemblies for it are so designed as to provide the best performance in a range of from 100 kbar to 200 kbar. Noncatalytic syntheses of diamond, stishovite and cubic boron nitride are described as examples of utilizing the apparatus. Some features of anvil fracture are also described.