Н2О as a Possible Initiator of Surface Graphitization of Impact Diamonds

The experimental results on etching of diamond crystals with octahedral and cubooctahedral habits at a temperature of 1000°С in wet argon are presented. It is found that at a low partial pressure, Н2О can act as an initiator (catalyst) of the surface graphitization of diamonds at the Р–Т-parameters of thermodynamic stability of graphite. The limiting stage of the diamond etching process in the presence of graphite on diamonds is the stage of graphite coating oxidation. Since the outer graphite coating is oxidized, there is no dependence of the etching (oxidation) rate on the morphology of diamond crystals.