Ultimate Deoxidation Method of Titanium Utilizing Y/YOCl/YCl3 Equilibrium

• Published in: Metallurgical and materials transactions. B, Process metallurgy and materials processing science Vol. 51; no. 2; pp. 433 - 442
• Main Authors: Iizuka, Akihiro, Ouchi, Takanari, Okabe, Toru H.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.04.2020; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Deoxidizing; Equilibrium; Equilibrium methods; Materials Science; Metal scrap; Metallic Materials; Nanotechnology; Scrap; Structural Materials; Surfaces and Interfaces; Thin Films; Titanium; Yttrium
• ISSN: 1073-5615; 1543-1916
• DOI: 10.1007/s11663-019-01742-6

Deoxidation methods of titanium (Ti) scrap and Ti powder have become increasingly important in recent years. Some rare earth (RE) metals with strong deoxidizing capabilities, including Y, La, Ce, and Ho, are candidate agents for the development of a new deoxidation technology. In this study, a new method was developed to directly remove oxygen (O) from Ti using the Y/YOCl/YCl 3 equilibrium. According to the calculation based on available thermodynamic data in the literature, the O concentration in β-Ti can be reduced to less than 10 ppm O at 1300 K (1027 °C) in the Y/YOCl/YCl 3 equilibrium. To demonstrate the effectiveness of this method using the Y/YOCl/YCl 3 equilibrium, the deoxidation limits of Ti samples using Y metal in YCl 3 ( l ) or in YCl 3 -NaCl-KCl ( l ) at 1300 K (1027 °C) were experimentally investigated in this study. As a result, the O concentrations in the Ti samples were from 30 to 60 ppm O in YCl 3 ( l ). This result revealed that Ti with extremely low O concentration can be reliably obtained using the RE/REOCl/RECl 3 equilibrium for the first time. The establishment of this process will realize efficient recycling of Ti scrap and production of low O concentration Ti powder, which contribute to the large-scale use of Ti products.