Identification of source and control of oxygen and nitrogen impurities in Kroll process for preparation of Ultra-soft titanium sponge

The titanium sponge is an important material for various applications, including in aerospace and defense fields. The impurity content in titanium sponge has a direct impact on the impurity content and defect formation of pure titanium and titanium alloys. In this study, the distribution of oxygen and nitrogen impurity elements in a titanium sponge specimen was studied, and the forms of O and N impurity elements were analyzed. Further, the forms of the impurity element O in TiCl 4 and liquid magnesium, and the introduction of O and N impurities during the titanium-sponge preparation were analyzed. Finally, the sources and contents of O and N impurities at different stages in the production were determined. The following measures were identified for producing the low-hardness and Ultra-soft titanium sponge. (1) The amounts of impurities MgO, SiO 2 , and Al 2 O 3 in refined magnesium need to be controlled. (2) The organic impurities containing O and C in TiCl 4 needs to be decreased. (3) The air tightness should be ensured during the whole process of preparing titanium sponge by magnesium thermal reduction distillation.