[T13] Non Ferrous Materials

[15F-T13-03] Passivation Coating on Titanium Powder Surface via SnCl4-Ti Gas-Solid Fluidization Reaction

*F. Yang^{1, 2}, Z. Feng^{1, 2}, X. Li^{1, 2}, C. Chen^{1, 2}, Z. Guo^{1, 2} (1.University of Science and Technology Beijing, China, 2.Southern Marine Science and Engineering Guangdong Laboratory, China)

Keywords:Passivation behavior, Gas–solid fluidization, Stannic chloride

In this study, a passivation coating is formed on Ti powder surface via SnCl₄-Ti gas-solid fluidization reaction using fluidized bed. It is found that at 200–350 ℃, Ti-Sn-Cl-O passivation layer is formed on Ti powder surface on account of the reaction among SnCl₄, oxide film on powder surface, and Ti matrix. Upon further increasing the temperature to above 500℃, deoxygenation reaction occurs accompanied by the formation of gaseous TiCl_m and TiO_xCl_y escaping from Ti powder matrix, resulting in the decreasing of surface oxygen content. Besides, elemental Sn and Ti-Sn compounds are formed on Ti powder surface, and part of Sn is diffused into titanium matrix. The passivation behavior is mainly consisted of oxygen film destruction and oxygen removal with the fluidization temperature increasing. Overall, the suitable temperature is about 350℃ to form a passivation coating on Ti powder surface, which can achieve oxidation isolation and deoxygenation in subsequent forming and sintering process.