Synthesis of β-sialon/Ti(C, N) powders from mineral waste residue via carbothermal reduction nitridation
Abstract
β-sialon/Ti(C, N) composite powders were synthesized via carbothermal reduction nitridation method with low-grade bauxite and ilmenite as starting materials and coke as the reducing agent. The influences of the synthesis temperature, the low-grade bauxite–ilmenite mass ratio, and the amount of coke additive on the phase transformation and morphology of β-sialon/Ti(C, N) composite powders were investigated with X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The results showed that the optimal experimental conditions for the CRN synthesis of β-sialon/Ti(C, N) composite powders were as follows: 4 h treatment, nitrogen atmosphere, and the theoretical coke quantity. When the ratio of ilmenite in raw materials increased from 10% to 50%, the synthesis temperature declined from 1400 °C to 1350 °C. The morphology of well-developed β-sialon crystals was columnar. After the carbothermal reduction nitridation process of ilmenite, the resultant Ti(C, N) particles were distributed dispersedly among the composite powders, and either Fe or Fe3Si existed in the products, depending on the reaction temperature.