Phase behavior of serpentine mineral by carbothermal reduction nitridation

Abstract 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-Si 3 N 4 grains. Serpentine could be transformed into high-temperature composites containing Mg 2 SiO 4 , β-Si 3 N 4 , Si 2 N 2 O and β-SiC at temperatures higher than 1400 °C. At 1550 °C, more Si 2 N 2 O was nitrided to β-Si 3 N 4 as the increase of carbon content, in the final products of samples with carbon addition excess 100 wt.% of theoretical quantity, Mg 2 SiO 4 coexisted with β-Si 3 N 4 as the main crystal phases. This transformation provided a feasible way of dealing with serpentine waste for high-temperature utilization.