분무건조법에 의해 제조된 Ti-Co-O계 산화물 분말의 고체 탄소에 의한 환원/침탄

Abstract

In the present study, the focus is on the analysis of carbothermal reduction of the titanium-cobalt-oxygen based oxide powder by solid carbon for the optimizing synthesis process of ultra fined TiC/Co composite powder. The titanium-cobalt-oxygen based oxide powder was prepared by the combination of the spray drying and desalting processes using the titanium dioxide powder and cobalt nitrate as the raw materials. The titanium-cobalt-oxygen based oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under a flowing argon atmosphere. The changes in the phase structure and thermal gravity of the mixture during carbothermal reduction were analysed using XRD and TGA. The synthesized titanium-cobalt-oxygen based oxide powder has a mixture of TiO2 and CoTiO3. This oxide powder was transformed to a mixed state of titanium carbide and cobalt by solid carbon through four steps of carbothermal reduction steps with increasing temperature; reduction of CoTiO3 to TiO2 and Co, reduction of TiO2 to the magneli phase(TinO2n-1, n>3), reduction of the magneli phase(TinO2n-1, n>3) to the TinO2n-1(2≤n≤3) phases, and reduction and carburization of the TinO2n-1(2≤n≤3) phases to titanium carbide.