Graphite etch rate

At 720°C diamond will burn in an oxygen jet. It is often stated in the literature that oxidation starts at 600°C. The theoretical onset of oxidation should be well below 600°C, because from the etching rates of Evans [44] for the lll)-plane in 1 bar oxygen a well below zero (w 0.02) is calculated. Linear extrapolation would give T w 340°C for = 0. However, in analogy with graphite there may be an accumulation of C-O complexes at the surface, which is faster then their removal between 300°C and 500°C [49]. Surface graphitization at F > 600°C points in this direction. 

Fig. 81 Variation of creep rate within the narrow range of strains for the neat amorphous polyimide (Vespel , DuPont) (a) and for the same polyimide filled with graphite micro-particles (b) [320]. T = 327°C, compressive stress a = 20MPa. In (c), SEM micrograph of the etched cut surface of graphite-containing sample is shown. Black graphite particles of about 5 2nm in size are seen...

---