Abstract
The ‘belt’ type high pressure apparatus, which has widely been used industrially for the synthesis of diamond and cBN in the pressure and temperature ranges of about 6 GPa and 1600°C, was modified to increase the pressure and temperature to the regions of 8 GPa and above 2000°C for the routine experiments of the new synthesis research on diamond and cBN. This was realized by adopting the optimum values of the shape parameters in the central parts of the apparatus and the press fitting conditions. An apparatus with the bore diameter of 30mm was constructed and used successfully in more than 600 runs for the synthesis, crystal growth and sintering of diamond and cBN in the 8 GPa pressure region.
