Study of carbide zirconium surface degassing using auger electron spectroscopy

Stabilization of the ZrC chemical composition is studied in 10-9 torr vacuum at 1500 K using electron auger spectroscopy, the methods of thermal electron emission and thermal desorption. Using the nondifferentiated auger spectra obtained is the relation of the carbon auger peak height to the background of inelastically reflected electrons - 2:3, and to the noise - 50:1. ZrC heat up to 2300 K is sufficient for cleaning its surface from O and S and does not promote its noticeable decarbonization. On the ZrC surface sulphur segregation is observed at 1750-2100 K. At 300-2100 K sulphur can exist on the ZrC surface in three different electron states. Its intensive desorption begins at 2300 K. In the 300-2300 K temperature range nitrogen is not a surface active addition. In the ZrC near-surface layer oxygen appears that decreases the ZrC work function and changes the n(E) density curve of the occupied states on the ZrC surface. The first peak of n(E) expands over 0.7 eV, the second one becomes lower. The stabilization rate of the ZrC surface composition is limited by the adsorption rates of CO, CO2, H2O and diffusion rates of C, O. The thermal emission and desorption methods are more sensitive to oxygen injection, than the method of electron auger spectroscopy