Chemical erosion of carbon doped with different fine-grain carbides

Several carbide-doped (SiC, TiC, V8C7, WC, ZrC) graphites have been produced. The erosion of these materials at low-energy (eV) hydrogen ion bombardment has been investigated using the weight-loss method, mass spectroscopy, ion beam analysis, and scanning electron microscopy (SEM). The erosion yields of the WC- and V8C7-doped graphites are reduced by a factor of 2 for 30 eV D at 300 K compared to pure graphite. This observed reduction is partly attributed to surface enrichment of carbide due to preferential C erosion. The other part is assigned to changes in the chemical erosion process (Y-surf) as well as at elevated temperatures in the thermal activated process (Y-therm). The reduction of both erosion processes is determined for all dopants to be more than 25% of the erosion yield of the undoped graphite. (C) 2001 Elsevier Science B.V. All rights reserved.