Self-propagating reaction mechanism of Mg–TiO2 system in preparation process of titanium powder by multi-stage reduction

• Published in: Rare metals 2021-09, Vol.40 (9), p.2645-2656
• Main Authors: Fan, Shi-Gang, Dou, Zhi-He, Zhang, Ting-An, Yan, Ji-Sen
• Format: Article
• Language: English
• Subjects: Adiabatic flow; Biomaterials; Chemistry and Materials Science; Compacts; Energy; Heating; Initial conditions; Materials Engineering; Materials Science; Mathematical analysis; Metallic Materials; Nanoscale Science and Technology; Original Article; Oxygen content; Physical Chemistry; Propagation modes; Reaction mechanisms; Reduction; Self propagating high temperature synthesis; Titanium; Titanium dioxide; Titanium oxides
• ISSN: 1001-0521; 1867-7185
• DOI: 10.1007/s12598-020-01554-7

The novel method for the preparation of titanium powder by multi-stage reduction was proposed. The primary reduction adopted self-propagating high-temperature synthesis (SHS) mode. This paper focuses on the primary reduction process of Mg–TiO 2 system under the condition of off-balance reaction. The effects of different material ratios, material arrangement methods and reaction initiation modes on the SHS reaction process of Mg–TiO 2 system and its reaction mechanism were systematically studied. SHS mode was used to Mg–TiO 2 system, and non-stoichiometric low-valent titanium oxide intermediate including α-Ti (Ti 2 O type) and TiO was directly obtained (with oxygen content of 13.93 wt%). SHS reaction initiated by local ignition is more sufficient than by overall heating method. Compared with the loose setting materials, the compacts can increase the effective contact interface of the reactants, and SHS reaction proceeds more sufficiently, which is favorable for obtaining lower oxygen content product. The adiabatic temperatures of the Mg–TiO 2 system at different initial conditions were calculated according to the improved calculation method. When the initial temperature is 298 K, the adiabatic temperature of Mg–TiO 2 system is between 1363 and 2067 K at different material ratios. Therefore, unreacted or partially excess Mg at the reaction front will diffuse into the unreacted region in gas or liquid form, thereby preheating the material and initiating further SHS reaction.