Metehan ERDOĞAN, Emre ERGÜL, İshak KARAKAYA

ERİMİŞ TUZ İÇİNDE ELEKTROKİMYASAL İNDİRGENME YÖNTEMİYLE SİLİSYUM ÜRETİMİ

Gözenekli silisyum dioksit peletlerinin 2,8 V potansiyel farkı uygulanarak CaCl2 tuzu ve CaCl2NaCl tuz çözeltisi içerisinde elektrodeoksidasyon yöntemiyle indirgenmesi incelenmiştir. Çalışma, katotta kullanılan iletken malzemelerin, sıcaklığın ve tane boyutunun indirgenmeye olan etkilerinin araştırılmasını içermektedir. Başlangıçta kullanılan malzemelerin ve elektroliz sonucunda elde edilen ürünlerin yapısı ve morfolojisi X-ışınları kırınımı analizi ve taramalı elektron mikroskobu ile belirlenmiştir. Nikel ve paslanmaz çelik katotta iletken malzemeler olarak kullanılmış ve katotta oluşan silisyumun katot iletken malzemesi olarak kullanılan metallerle reaksiyona girdiği görülmüştür. Xışınları kırınımı analizi ile silisyumun, katot iletken malzemesi olarak kullanılan nikelle nikel-silis bileşikleri oluşturduğu, paslanmaz çelik içindeki demirle de demir-silis bileşikleri oluşturduğu belirlenmiştir. Oluşan nikel-silis bileşiklerinin, miktar olarak, demir-silis bileşiklerinden daha fazla olduğu görülmüştür. Sonuçlar, akım zaman grafikleri, kompozisyonlar ve mikroyapılar incelenerek yorumlanmıştır

Production of Silicon by the Electrochemical Reduction Technique in Molten Salt

Electrodeoxidation of porous SiO2 pellets in molten CaCl2 salt and CaCl2-NaCl salt mixture was investigated by applying 2.8 V potential. Aim of the study was to investigate the effects of cathode contacting materials, temperature and particle size. The structure and morphology of starting materials and electrolysis products were determined by X-ray diffraction analysis and scanning electron microscopy. Nickel and stainless steel cathode contacting materials were used to see the extent of reactions between silicon produced at the cathode and the contacting materials. X-ray diffraction patterns showed that silicon produced at the cathode reacted with nickel, and iron in stainless steel to form Ni-Si and Fe-Si compounds respectively. It was also observed that the amount of Ni-Si compounds formed at the nickel cathode was more than the amount of Fe-Si compounds formed at the stainless steel cathode. The results were interpreted from variation of current versus time graphs under different conditions, microstructures and composition of the reduced pellets

PDF

___

Baker, H., 1993, ed. ASM Handbook, Cilt 3, ASM International: Ohio.
Barin, I., Knacke, O., Kubaschewski, O., 1977, Thermochemical Properties of Inorganic Substances, Springer, Berlin.
Carleton K. L., Olson J. M., Kibbler A., 1983, "Electrochemical Nucleation and Growth of Silicon in Molten Fluorides", Journal of Electrochemical Society, Cilt 130, Sayı: 4, ss. 782-786.
Chen G. Z., Fray D. J., Farthing T. W., 2000, "Direct Electrochemical Reduction of Titanium Dioxide to Titanium in Molten Calcium Chloride", Nature, Cilt 407, ss. 361-364.
Elwell D., Rao G. M., 1988, "Electrolytic Production of Silicon", Journal of Appled Electrochemistry, Cilt 18, ss. 15-22.
Henneberg, E., Acker J., Roever I., Roewer G., Bohmhammel K., 2002, "Synthesis of Nanocrystalline Silicon in the System La-Si-HCl: Thermoanalytical Investigations, Thermochimica Acta, Cilt 382, ss. 297-301.
Jin X., Gao P., Wang D., Hu X., Chen G. Z., 2004, "Electrochemical Preparation of Silicon and its Alloys from Solid Oxides in Molten Calcium Chloride", Angewandte Chemie, Cilt 43, ss. 733-736.
Nohira T., Yasuda K., Ito Y., 2003, "Pinpoint and Bulk Electrochemical Reduction of Insulating Silicon Dioxide to Silicon", Nature Materials, Cilt 2, ss. 397-401.
Olson J. M., Carleton K. L., 1981, "A Semipermeable Anode for Silicon Electrorefining", Journal of Electrochemical Society, Cilt 128, Sayı 12, ss. 1152-1156.
Pistorius P. C., Fray D. J., 2006, "Formation of Silicon by Electrodeoxidation, and Implications for Titanium Metal Production", Journal of the South African Institute of Mining and Metallurgy, Cilt 106, ss. 31-41.
Rao G. M., Elwell D., Feigelson R. S., 1981, "Electrodeposition of Silicon onto Graphite", Journal of Electrochemical Society, Cilt 128, Sayı 8, ss. 1708-1711.
Sharma I. G., Mukherjee T. K., 1986, "A Study on Purification of Metallurgical Grade Silicon by Molten Salt Electrorefining", Metallurgical Transactions B, Cilt 17B, ss. 395.
Xiao W., Jin X., Deng Y., Wang D., Hu X., Chen G. Z., 2006, "Electrochemically Driven Three-phase Interlines into Insulator Compounds: Electroreduction of Solid SiO2 in Molten CaCl2", ChemPhysChem, Cilt 7, ss. 1750-1758.
Yasuda K., Nohira T., Amezawa K., Ogata Y. H., Ito Y., 2005, "Electrolytic Reduction of a Powdermolded SiO2 Pellet in Molten CaCl2 and Acceleration of Reduction by Si Addition to the Pellet", Journal of The Electrochemical Society, Cilt 152, Sayı: 12, ss. D69-D74.
Yasuda K., Nohira T., Hagiwara R., Ogata Y. H., 2007, "Direct Electrolytic Reduction of Solid SiO2 in Molten CaCl2 for the Production of Solar Grade Silicon", Journal of the Electrochemical Society, Cilt 154, ss. E95-E101.
Zulehner W., 1993, Ullman's Encyclopedia of Industrial Chemistry, (ed. B. E. W. Zulehner, S. Hawkins, W. Russey, G. Schulz), VHC, Weinheim.