Effect of catalytic condition on the properties of carbon nanotubes/calcium aluminate cement and its synthesis mechanism

Abstract Carbon nanotubes/calcium aluminate cement (CNTs/CAC) have endowed refractory castables with excellent performance. However, the properties of CNTs/CAC at varying catalytic conditions were significantly affected by the characteristics of carbon matters and the microstructure of cement, especially oxidation resistance and water dispersibility. The CNTs/CAC and the pyrolysis process of its precursors were characterized by X‐ray diffractometry, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and thermogravimetry‐Fourier transform. The optimum catalyst content of cement was determined to be 0.2 wt.% (Fe count), the optimal catalytic temperature was 700°C, and the optimal catalytic time was 3 h. The graphitization degree of carbon and the microstructure of cobweb‐like carbon/cement particles were optimized within the optimal catalytic conditions, thereby improving the oxidation resistance and water dispersion of CNTs/CAC. In addition, the research of the CNTs/CAC pyrolysis process has also shown that bamboo‐shaped carbon nanotubes were aggregated, interweaved, and embedded within the interstices of calcium aluminate particles to form a cobweb‐like microstructure during the CNTs/CAC formation process.