Process for the preparation of an insulating material for thermo elements used in high-pressure furnaces

摘要

An insulating material 1 for thermo elements used in high- pressure furnaces is prepared by the isostatic compression of hexagonal boron nitride containing at most 1.5 wt-% of impurities other than carbon and oxygen at a temperature of at least 1600 degrees C and at a pressure of at least 50 MPa.