Some characteristics of the formation of chromium nitrides

An investigation was carried out into the kinetics of the formation of chromium nitrides in nitrogen and ammonia streams. The kinetic parameters of the process were calculated. It was established that the reaction of chromium with nitrogen results in the simultaneous formation of Cr2N and CrN. The difference in thermal stability between the chromium nitrides in a nitrogen atmosphere is responsible for the preparation in a pure form of chromium nitride of composition Cr2N. The methods of chemical and x-ray diffraction analyses were used to determine more accurately the boundaries of the Cr2N homogeneity range. The nitrogen content of Cr2N in its homogeneity range is controlled by the time factor. In a nitrogen stream, it is impossible to produce CrN free from Cr2N. The thermal stability of CrN is greater in an ammonia atmosphere, which enable this nitride to be obtained in a pure form.