Experimental study of the effect of nitrogen on titanium-arc cathode erosion

Experimental data on the dependence of titanium erosion rate on cathode temperature, Ar, and N-2 pressure from vacuum to 1 torr and are motion are presented. Erosion rate is found to decrease with conditions that promote cathode poisoning/contamination. Higher cathode temperatures result in enhanced nitriding (poisoning), leading to a reduced erosion rate. A critical nitrogen pressure (0.001 torr) exists where a sharp drop in erosion is measured. Steered arcs show lower erosion rate values of 38 and 15 mu g/C for argon and nitrogen, when compared to random 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.