EXPERIMENTAL-STUDY OF THE EFFECT OF NITROGEN ON TITANIUM-ARC CATHODE EROSION

Experimental data on the dependence of titanium erosion rate on cathod e temperature, Ar, and N-2 pressure from vacuum to 1 torr and are moti on are presented. Erosion rate is found to decrease with conditions th at promote cathode poisoning/contamination. Higher cathode temperature s result in enhanced nitriding (poisoning), leading to a reduced erosi on rate. A critical nitrogen pressure (0.001 torr) exists where a shar p drop in erosion is measured. Steered arcs show lower erosion rate va lues of 38 and 15 mu g/C for argon and nitrogen, when compared to rand om are values of 45 and 35 mu g/C. Erosion rate studies on TiN-coated cathodes show a low value of around 22 mu g/C.