Process for making diamond and cubic boron nitride compacts

摘要

Optical windows for hostile environments have been made from diamond and adamantine boron nitride compacts. The compact windows can comprise a single layer of large crystals bonded in a matrix. For example, they are made by exposing a sample of diamond (425-1700 micron) in a diamond and graphite matrix to high pressure-high temperature conditions (e.g., 50 Kbar at 1400 DEG C. to 85 Kbar at 1800 DEG C.). A typical boron nitride reaction zone assembly (cell) is shown in FIG. 1, in which carbon heater tube 1 is surrounded by tantalum foil sleeve 2. The sample of pyrolytic boron nitride 3 is disposed between carbon discs 5, tantalum foil discs 4 and hot pressed boron nitride plugs 6. The optical windows produced are capable of transmitting infrared light and visible light.