Nitriding and nitrocarburizing under reduced pressure
Nitriding and nitrocarburizing - Industrial Processes and Practices

This process is similar to gas nitriding in a vacuum purge furnace, comparable to the furnaces used for tempering steels after vacuum quenching. The nitriding medium is a gaseous mixture under reduced pressure (100 to 400 hPa). The compounds used are ammonia-based, with possible additions of methane (nitrocarburizing) and oxygen (pure or in the form of oxidized varieties, N ₂ O), whose role seems paramount in controlling the combination layer . The reduction in pressure increases the mean free path and thus the stability of the gaseous molecules introduced, as well...