Direct Electrochemical Preparation of Nanostructured Silicon Carbide and Its Nitridation Behavior

Abstract

Silicon carbide was synthesized from mixtures of SiO 2 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 SiO 2 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 CaCl 2 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 CaSiO 3 as a transient phase. Based on the experimental results a multipath reaction mechanism is proposed, consisting of the electrochemical reduction of SiO 2 and CaSiO 3 to Si and the subsequent in-situ carbonization of the Si formed to SiC. The effect of N 2 at high temperature on the electrochemically synthesized SiC was investigated and the formation of nanowire Si 2 N 2 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.

Facile Electrochemical Synthesis of Nanoscale (TiNbTaZrHf)C High‐Entropy Carbide Powder

“…It is noted that the final product contained no residual carbon since any unreacted graphite was converted during polarisation into CaC 2 that was then removed in the washing step. [37] High-magnification BS-SEM images of the HEC products obtained by electro-deoxidation illustrated that both products had a powdery morphology and consisted of approximately equiaxed but noticeably jagged particles with sizes between 15-80 nm, typically agglomerated into clusters (Figures 2 d,e). Figure 2.…”

Facile and Scalable Electrochemical Synthesis of Ta-Nb Alloy Powders for Capacitors

“…About 500 g of anhydrous CaCl 2 salt, prepared from CaCl 2 •2H 2 O (98+%, Sigma Aldrich) via thermal and vacuum drying, 37 was filled into an alumina crucible. This was placed inside an Inconel hightemperature reactor that was sealed leak-tight with a steel lid that had feedthroughs for the various cell components.…”

Facile Electrochemical Preparation of Nano-sized Ultra-high-temperature Ta1−xHfxC Ceramic Powders

“…24,25 The method has also been extended towards the preparation of several binary and ternary carbides, by reducing oxides in the presence of carbon so as to enable the in situ reaction of the freshly released metals with the surrounding carbon. [26][27][28][29][30][31][32][33][34][35] In this way, the first synthesis of a nano-sized high-entropy carbide powder has lately been accomplished. 36 z E-mail: jagadeesh.sure@vit.ac.in; hkk@kangwon.ac.kr *Electrochemical Society Member This article reports the successful synthesis of Ta 1−x Hf x C ceramic powders via the FFC electro-deoxidation technique.…”