Formation of massive cementite layers on iron by ferritic carburising in the additional presence of ammonia

Abstract

Massive Fe3C compound layers were grown on α-Fe substrates at 823 K by a gas carburising process in the additional presence of NH3. Whereas pure carburising employing a CO/H2/N2 gas mixture leads, besides Fe3C formation, to severe graphite formation, the latter can be suppressed by a partial substitution of N2 in the gas mixture by NH3. The growth kinetics of the obtained massive Fe3C layer can be described by a two-stage process.