Abstract
Carbon source precursors for high-grade, clean, and low-carbon refractories were obtained by in situ exfoliation of flake graphite (FG) and phenol–formaldehyde resin (PF) composites with three-roll milling (TRM) for the fabrication of graphite nanoplatelets. In addition, by using Ni(NO3)2·6H2O as a catalyst in the pyrolysis process, multidimensional carbon nanostructures were obtained with coexisting graphite nanoplatelets (GNPs), glassy carbon (GC), and carbon nanotubes (CNTs). The resulting GNPs (exfoliated 16 times) had sizes of 10–30 μm, thicknesses of 30–50 nm, and could be uniformly dispersed in GC from the PF pyrolysis. Moreover, Ni(NO3)2·6H2O played a key role in the formation and growth of CNTs from a catalytic pyrolysis of partial PF with the V–S/tip growth mechanisms. The resulting multidimensional carbon nanostructures with GNPs/GC/CNTs are attributed to the shear force of the TRM process, pyrolysis, and catalytic action of nitrates. This method reduced the production costs of carbon source precursors for low-carbon refractories, and the precursors exhibited excellent performances when fabricated on large scales.
Highlights
Carbon-containing refractories, which exhibit excellent thermal shock resistances and corrosion resistances because of the additional carbon, have been widely applied over the last few decades [1,2]
The structure of flake graphite (FG) in phenol–formaldehyde resin (PF) exfoliated with the three-roll milling (TRM) technology and the catalytic pyrolysis of PF with Ni(NO3)2·6H2O at 1000 ◦C were investigated
The following conclusions can be drawn: (1) The TRM method enabled the simple exfoliation of FG into micro/nano graphite platelets (GNPs) in high-viscosity PF
Summary
Carbon-containing refractories, which exhibit excellent thermal shock resistances and corrosion resistances because of the additional carbon, have been widely applied over the last few decades [1,2]. Carbon black (CB), as a zero-dimensional nano-sized carbon source, replaced FG partially or entirely Thereby, it reduced the carbon content and improved the mechanical performance and thermal shock resistance of Al2O3–C LCCRs [10,11]. The previously mentioned nano-carbon sources (CB, CNTs/CFs, graphene, and GONs) are expensive because of their complicated fabrication processes, and it becomes very difficult to disperse/distribute them homogeneously in the whole LCCR matrix. This restrains their large-scale applications in LCCRs and the potential for long-term development of high-quality steelmaking and external refining technologies. A low-cost route for the large-scale preparation of an applicable carbon source precursor for LCCRs must be developed to meet the performance requirements of advanced steelmaking
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