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.