Formation of nanocarbon structures in MgO-C refractories matrix: Influence of Al and Si additives

摘要

The in-situ catalytic formation of various nanocarbon structures in the matrix of MgO-C refractories with Ni-containing catalyst and different additives was investigated in the present work. In comparison with the specimens containing Si powder, the addition of metallic Al can be more favorable for the growth of straight and bamboo-like carbon nanotubes in the specimens under the function of the catalyst. Nevertheless, only Ni-encapsulating and hollow carbon onions appeared in the specimens without any additives at all the investigated temperatures. It was suggested that adding metallic Al or Si powder can decrease the partial pressures of oxidizing gases and increase that of hydrocarbon gases in the specimens due to the information of ceramic phases, and the influence of metallic Al was more considerable. Also, the formation mechanisms of these various nanocarbon structures can be determined by the competing processes between the catalyst forward and the carbon shell growth. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.