In this paper, spectroscopic and electrostatic probe measurements are made to examine the characteristics of a supersonic dc plasma jet near the surface of titanium plate during a nitriding treatment. The low-pressure nitriding process is done using a mixture of ammonia, nitrogen, and hydrogen gasses. Heating effects from the plasma are evaluated with nickel slug and thermocouple attached to the plate. The authors present the results of their study along with observations, insights, and suggestions on how to improve plasma nitriding processes. Paper includes a German-language abstract.

Ammonia and a mixture of nitrogen and hydrogen are used for material processing. Since these gases are chemically active, the processing efficiency is enhanced. This article describes a study to understand the physical properties of ammonia and a mixture of nitrogen and hydrogen plasmas inside and outside an arcjet generator. Spectroscopic measurement is made, and several plasma properties are determined from the data. The result shows that the H-atom electronic excitation temperature and the nitrogen rotational excitation temperature decreased from 7000-11000 K in the constrictor to about 4000 K and to 1000-1500 K, respectively, on the nozzle exit with mass flow rates of 0.1-0.2 g/s at input powers of 7-12 kW. However, the NH rotational excitation temperature did not show a significant axial decrease even in the downstream plume. Paper includes a German-language abstract.