Synthesis of Ni–TiC Composite by Ball Milling and Heat Treatment of NiO/TiO2/C Powder Mixture

Abstract

In this study, a Ni–TiC composite was synthesized by the carbothermic reduction of activated NiO/TiO2/C powder mixture. The effect of 0-, 2-, 5-, and 10-h ball milling of the sample on the reduction process was investigated. Results of XRD pattern from milled samples showed that no reaction occurred between NiO, TiO2, and carbon due to milling. FESEM images for samples milled for 2, 5, and 10 h revealed the fine distribution of the brittle oxide particles in the matrix of graphite, as a ductile phase. Particle size reduction was also noticeable, especially in the case of oxide particles. By increasing the milling time, agglomeration of particles was also observed. Results of the thermogravimetry analysis of milled and un-milled mixtures showed the onset temperature of reduction for NiO decreased from 867 °C in the un-milled sample to 582, 571, and 560 °C in samples activated for 2, 5, and 10 h, respectively. Also, the onset temperature of the reduction of TiO2 decreased from 1029 for the sample milled for 2 h to 1019 and 1004 °C for samples milled for 5 and 10 h, respectively. The XRD pattern of the heat-treated milled powder mixture for 1 h under vacuum proved that Ni–TiC composite was formed at 1100 °C. It was found that bulk Ni–TiC composite could be synthesized by the heat treatment of activated powder at 1300 °C. Formation of TiC quadrilateral particles as reinforcement in the continuous matrix of Ni was evident at this temperature. Furthermore, the best morphology with the most appropriate particle size distribution was observed in the sample milled for 2 h.