Effect of external electromagnetic field and bias voltage on the chemical vapor growth of the carbon micro-coils and their properties

Abstract

Carbon micro-coils were obtained by the chemical vapor deposition using a Ni-catalytic pyrolysis of acetylene at 770°C with hydrogen sulfide as impurity, with and without an external electromagnetic field (EM) and applying a DC and/or AC bias voltage to the substrate. The effects of the EM field and bias voltage on the growth rate, morphology and properties of the as-grown carbon micro-coils were examined. A pale red-purple light emission was observed during the reaction. The EM field resulted in full decomposition of acetylene and coil yield of 1.6–2.3 times higher than that without the external EM field was obtained. The coil yield obtained by the application of bias voltage increased linearly with the increasing of bias voltage. The coil yield obtained with 400 V DC bias and 1000 V AC bias with the external EM field were 2.2 and 2.3 times higher than that without the EM field and no applied bias, respectively. The very regular-coiled carbon fibers with a flat fiber cross-section and irregular-coiled carbon fibers with a circular fiber cross-section were obtained with the EM field and without the EM field irrespective of the bias voltage, respectively.