Kinetic aspects of low-pressure nitriding process

The purpose of this work was to theoretically and experimentally study the reactions that occur during low-pressure nitriding. A series of specimens made of 42CrMo4 and 41CrAlMo7 and C22 steels were low-pressure nitrided. The structure of the materials, the hardness and the thickness of the nitride layers, as well as any reactions that occurred in the gas and solid phases were tested. The process kinetics were discussed. The findings showed that a build-up of the nitrided layer from a low-pressure process depends on the kinetics of surface processes. However, a characterization of the process with nitriding potential is not justified and should be replaced with a rate of ammonia dissociation in low-pressure processes.