Direct Electrochemical Preparation of Nanostructured Silicon Carbide and Its Nitridation Behavior. Issue 14 (30th October 2018)

• Record Type: Journal Article
• Authors: Vishnu, D. Sri Maha; Sure, Jagadeesh; Kim, Hyun-Kyung; Kim, Ji-Young; Kumar, R. Vasant; Schwandt, Carsten
• Is Part Of: Journal of the Electrochemical Society. Volume 165:Issue 14(2018)
• Page Start: D731
• Page End: D742
• Publication Date: 2018-10-30
• Subjects: Electrosynthesis -- High Temperature Materials -- Molten Salts -- electrochemical reduction -- FFC-Cambridge process -- silicon carbide; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0591814jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Silicon carbide was synthesized from mixtures of SiO2 and graphite by applying the concept of the FFC-Cambridge process and several fundamental aspects of the synthesis route were investigated. Porous disks composed of powders of SiO2 and graphite in molar ratios of 1:0.5, 1:1 and 1:1.5 were prepared by sintering in inert atmosphere and subjected to electro-deoxidation in molten CaCl2 at 1173 K under a range of experimental conditions. Disks of molar ratio 1:1.5, reduced at an applied voltage of 2.8 V for a duration of 6 h, yielded exclusively phase-pure SiC of nanowire morphology as the reaction product, while the other precursor compositions provided significant amounts of calcium silicides. Voltages lower than 2.8 V gave mixtures of SiC with elemental Si and graphite, and voltages higher than that gave CaSi alone. Shorter electro-deoxidation times led to incomplete reduction and allowed for the identification of CaSiO3 as a transient phase. Based on the experimental results a multipath reaction mechanism is proposed, consisting of the electrochemical reduction of SiO2 and CaSiO3 to Si and the subsequent in-situ carbonization of the Si formed to SiC. The effect of N2 at high temperature on the electrochemically synthesized SiC was investigated and the formation of nanowire Si2 N2 O was observed. Overall, the process presented is a facile single-step and low-temperature method for the synthesis of SiC with possible commercial prospects.