Phase behavior of serpentine mineral by carbothermal reduction nitridation

In this paper, the effects of reductant addition and reaction temperature on phase behavior of serpentine by in situ carbothermal reduction nitridation (CRN) treatment were studied. A brief discussion on the synthesis mechanism of CRN process was also included. The results show that temperature and carbon content were two essential factors that determined the nitridation of serpentine and the formation of β-Si3N4 grains. Serpentine could be transformed into high-temperature composites containing Mg2SiO4, β-Si3N4, Si2N2O and β-SiC at temperatures higher than 1400 °C. At 1550 °C, more Si2N2O was nitrided to β-Si3N4 as the increase of carbon content, in the final products of samples with carbon addition excess 100 wt.% of theoretical quantity, Mg2SiO4 coexisted with β-Si3N4 as the main crystal phases. This transformation provided a feasible way of dealing with serpentine waste for high-temperature utilization.