Production of Silicon by the Electrochemical Reduction Technique in Molten Salt

Abstract

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.

Keywords

• Electrochemical Reduction
• Electrodeoxidation
• Silicon
• Silicon Dioxide

ERİMİŞ TUZ İÇİNDE ELEKTROKİMYASAL İNDİRGENME YÖNTEMİYLE SİLİSYUM ÜRETİMİ

Öz

Gözenekli silisyum dioksit peletlerinin 2,8 V potansiyel farkı uygulanarak CaCl2 tuzu ve CaCl2-NaCl 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. X-ışınları 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.

Anahtar Kelimeler

• Elektrodeoksidasyon
• Elektrokimyasal İndirgeme
• Silisyum
• Silisyum Dioksit

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