Reduced brittleness of multi-walled carbon nanotubes (MWCNTs) containing Al_2O_3-C refractories with boron carbide

摘要

Boron carbide (B_4C) additive was adopted to decrease the brittleness of MWCNTs and silicon (Si) containing Al_2O_3-C refractories through accommodating the formation of ceramic phases. The corresponding phase compositions and microstructures of Al_2O_3-C refractories were investigated by means of X-ray diffraction (XRD), Raman spectra, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The mechanical properties were investigated by means of three-point bending test and the thermal shock resistance was evaluated through traditional water quenching method combined with wedge splitting test. The results show that B_4C could favor the growth of in-situ MWCNTs from pyrolysis of resin binder at 800 ℃. Additionally, B_4C additive suppresses the SiC formation at 1400 ℃ attributes to the decreased SiO (g) pressure. In comparison with the Si alone containing refractories, much more residual MWCNTs and in-situ formed MWCNTs contribute to lower brittleness, leading to better thermal shock resistance of B_4C and Si containing Al_2O_3-C refractories.