Effect of Multiwalled Carbon Nanotubes on the Thermal Conductivity and Porosity Characteristics of Blast Furnace Carbon Refractories

Abstract

Different amounts of carbon nanotubes (CNTs) (0-5 mass pct) containing carbon refractory specimens for a blast furnace were prepared and coked for 3 hours at 1473 K (1200°C) and 1673 K (1400°C). The thermal conductivity and porosity characteristics of the coked specimens were evaluated using the flash diffusivity technique and mercury porosimetry, respectively. It was found that CNTs acted as carbon source, and most of them were consumed during coking. With the increase of CNT content, the aggregation of CNTs became more severe, the amount of SiC whiskers formed increased and their aspect ratio became larger, and the SiC whiskers tended to be distributed nonhomogeneously. The thermal conductivity of a 4 mass pct CNT containing a carbon specimen was highest because of the contributions of SiC and residual CNTs. The porosity characteristics of a 0.5 mass pct CNT containing a carbon specimen was best because of the uniform filling of SiC whiskers. The excessive addition of CNTs degraded the porosity characteristics because of the severe aggregation of CNTs.

Effect of mixing on the properties of nanocarbon containing Al2O3‐C continuous casting refractories

“…Nano carbon sources possess high reactivity because of its high surface area, which can form in situ ceramic phases like carbides and nitrides at much lower temperature, thereby improving mechanical properties . But the uniform dispersion and distribution of nano carbon sources in the composition are the most important to get the advantages of its use . In the present study, nanocarbon is used as a carbon source along with graphite in alumina‐carbon system.…”

Effect of Artificial Graphite and Nickel Nitrate on the Microstructure and Properties of Carbon Blocks for Blast Furnace

“…For instance, Li Yiwei et al [5] reported that thermal conductivity of carbon blocks could be increased from 9 W•m -1 •K -1 to 35 W•m -1 •K -1 when anthracite was totally replaced by artificial graphite. Xilai Chen et al [6] demonstrated that thermal conductivity of carbon blocks fired at 1400 o C could be increased from about 16.5 W•m -1 •K -1 to 20.5 W•m -1 •K -1 when 4 mass pct CNTs was added. Also, Xilai Chen et al [7] found that adding reactive-Al 2 O 3 had positive effect on mean pore diameter and thermal conductivity of carbon blocks due to its more efficient filling of pores and higher thermal conductivity than that of brown corundum.…”