Effect of Zirconium on Boron Removal in Electromagnetic Solidification Refinement of Silicon from Si-Al Melt

Abstract:

This work investigates the removal of B in Si by the addition of Zr in the electromagnetic solidification refinement of silicon-aluminum melts. As Zr has a strong affinity for B and can form the thermodynamically stable compound of ZrB₂, the B content of lower-grade Si is expected to be effectively removed by adding a small amount of Zr to the Si-55 at% Al melt. The results show that Zr is strongly responsible for the decrease in B content of refined Si. The removal fraction of B significantly increased from 60.2% to 97.3% by adding a small amount of Zr (0 to 3500 ppmw). In addition, the removal fraction of Zr from Si was found to be as high as 98.6%; however, its residual content in the refined Si was significantly larger than its solid solubility in Si, possibly due to the non-equilibrium solidification occurring during the refining process.

• Periodical: Materials Science Forum (Volume 833)
• Pages: 97-100
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.833.97
• Online since: November 2015
• Authors: Yun Lei*, Wen Hui Ma, Kui Xian Wei, Ji Jun Wu, Guo Qiang Lv, Yong Nian Dai, Kazuki Morita
• Keywords: Boron Removal, Electromagnetic Solidification Refining, Si Purification, Si-Al Melt, ZrB₂

References

[1] K. Morita and T. Yoshikawa, Thermodynamic evaluation of new metallurgical refining processes for SOG-silicon production, Trans. Nonferrous Met. Soc. China, 21(2011), 685-690.

DOI: 10.1016/s1003-6326(11)60766-8

[2] T. Yoshikawa and K. Morita, Continuous solidification of Si from Si-Al melt under the induction heating, ISIJ Int., 47(2007), 582-584.

DOI: 10.2355/isijinternational.47.582

[3] T. Yoshikawa, K. Arimura and K. Morita, Boron removal by titanium addition in solidification refining of silicon with Si-Al melt, Metall. and Mater. Trans. B, 36B (2005), 837-842.

DOI: 10.1007/s11663-005-0085-1

[4] I. Barin, Thermochemical data of pure substances, VCH, Weinheim, Germany, 1989, p.1384, 1523 and 1708.

[5] H. Okamoto, The Si-Zr (Silicon-zirconium) system, Bull. Alloy Phase Diagr., 11 (1990), 513-519.

DOI: 10.1007/bf02898272

[6] J. Murray, A. Peruzzi and J. P. Abriata, The Al-Zr (Aluminum-zirconium) system, J. Phase Equilib., 13(1992), 277-291.

DOI: 10.1007/bf02667556

[7] E. T. Turkdogan, Physical Chmestry of High Temperature Technology, Academic Press, New York, 1980, p.5, 22, 24.

[8] S. H. Whang, D. P. Pope and C. T. Liu, Proceedings of the Second ASM Conference on High Temperature Aluminides and Intermetallics, Elsevier Science Publisher Ltd., San Diego, 1992, p.27.

[9] Y. Q. Li, Y. Tan, J. Y. Li, Q. Xu and Y. Liu, Effect of Sn content on microstructure and boron distribution in Si-Al alloy, J. Alloy Compd., 583 (2014), 85-90.

DOI: 10.1016/j.jallcom.2013.08.145

[10] K. Tang, E.J. Øvrelid, G. Tranell, M. Tangstad: Thermochemical and kinetic databases for the solar cell silicon materials, The Twelfth International Ferroalloys Congress: Sustainable Future, June 6-9, Helsinki, Finland, (2010).

DOI: 10.1007/978-3-642-02044-5_13