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

Some phenomena occurring under the simultaneous influence of oxygen ga s and helium ion bombardment of graphite and graphite compounds contai ning Ti and B are described. The ion energy was 800 eV. The incoming f luxes 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 du e to ion induced stresses was observed on the pure fine grain graphite and on the graphite compounds. Under oxygen influence, relief formati on 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 ou tput from ultradeep layers seems to be the result of a number of proce sses including ion assisted oxygen penetration in graphite layers, dis solution of titanium in the graphite and its segregation on the surfac e.