EROSION OF GRAPHITE AND GRAPHITE COMPOUNDS UNDER OXYGEN GAS AND LIGHT-ION IRRADIATION

Some phenomena occurring under the simultaneous influence of oxygen gas and helium ion bombardment of graphite and graphite compounds containing Ti and B are described. The ion energy was 800 eV. The incoming fluxes of ions as well as oxygen molecules were as much as 2.0 x 10(16) cm-2 s-1. It is shown, that the presence of oxygen increased graphite erosion by approximately a factor of 100 at T = 1300-degrees-C owing to CO molecule formation. Relief (pores, whiskers, cones) formation due to ion induced stresses was observed on the pure fine grain graphite and on the graphite compounds. Under oxygen influence, relief formation was accelerated. Titanium output from a depth of more than 100 mum was registered when a compound containing C + (15% TiC + 1% B) by mass was irradiated by combined He+/O2 flow at 1300-degrees-C. Titanium output from ultradeep layers seems to be the result of a number of processes including ion assisted oxygen penetration in graphite layers, dissolution of titanium in the graphite and its segregation on the surface.