EFFICIENCY OF DIFFERENT CARBON SOURCES DURING SINTERING OF CR-PREALLOYED PM STEELS: GRAPHENE, GRAPHITE OR CARBON BLACK?

Paper in proceeding, 2014

Prerequisite for development of inter-particle necks as well as carbon dissolution in the steel matrix is efficient removal of the iron oxide layer, covering surface of the base steel powder. Reactivity of admixed carbon source strongly affects efficiency of the surface oxide removal and so determines inter-particle necks development, further carbon dissolution and connected to this microstructure development. The present study is focused on the critical evaluation of the parameters, determining chemical reactivity of different carbon sources. Effect of admixing of number of different carbon sources – graphene nanoplatelets, synthetic and natural graphite grades with different particle size as well as carbon black powders – on the sintering behaviour of Cr-prealloyed powder was evaluated. Deoxidation, microstructure and inter-particle necks development were studied by means of metallography and fractography. Carbon source structure, powder size and interatomic bond characteristics were established to be the most important properties determining carbon reactivity.