When the carbon content of the magnesia carbon brick is reduced and is still introduced by the -100 mesh graphite used in the conventional magnesia carbon brick, there is a problem that the amount of graphite is small and cannot be continuous, which is resistant to slag penetration and mitigation of expansion stress. In terms of it, it is very unfavorable. In order to achieve the continuous distribution of carbon components in magnesia carbon bricks, the main research directions at home and abroad are basically the miniaturization of carbon components.
In 2003, Japan proposed the concept of “nanostructured matrix”, which is the transformation of materials through thermal expansion and contraction through the addition of nano-carbon black with high specific surface area, and the flexibility between nano-particles and nanopores. Wait to absorb. Tang Guangsheng et al. prepared a low carbon magnesium carbon sample with a carbon mass fraction of 3% using different types of carbon black. By evaluating the thermal shock resistance of the sample, a conventional magnesium carbon sample containing 16% by mass of graphite was used. Contrast, it was found that after 5 thermal cycles, the low carbon magnesium carbon sample added with nano carbon black N220 has thermal shock resistance comparable to that of the conventional sample. Shi Xiaoqiang et al studied the effects of the addition of nano-carbon black on the mechanical properties and thermal shock resistance of magnesia-carbon bricks. The results show that the addition of nano-carbon black can improve the mechanical properties and thermal shock resistance of magnesia-carbon bricks; When it is 5% (according to phenolic resin), the comprehensive mechanical properties of magnesia carbon bricks are optimal. Based on the strong specific surface area, nano carbon black has greatly improved and improved the performance of magnesia carbon brick.
Since nano-carbon black is amorphous and has a large specific surface area, carbon black is more easily oxidized than scaly graphite. To this end, some scholars have proposed pre-treatment of nano-carbon black to prepare composite powder to improve its oxidation resistance. For example, Yan Zhengguo used boric acid and carbon black as raw materials to prepare B4C-C composite powder by carbothermal reduction method, which obviously enhanced the thermal shock resistance and oxidation resistance of magnesia carbon brick. Hua Xujun et al. The TiC-C composite powder also plays a good role in protecting carbon oxidation. In addition, the attractive form of carbon is carbon nanotubes and carbon nanofibers. Carbon nanotubes or carbon nanofibers have superior performance in terms of mechanical properties and thermal properties compared to isotropic nanocarbon blacks. Fuchimoto et al. first introduced nano-scale carbon fiber into the material. The introduction of fiber changed the matrix structure and reduced the expansion of thermal stress crack, which effectively improved the thermal shock resistance of magnesia carbon brick. By introducing carbon nanotubes, Zhu et al. make low carbon magnesium carbon have higher strength retention and thermal shock resistance than traditional magnesium carbon materials.
Although the introduction of carbon nanotubes and the like plays a certain role in improving the performance of low carbon magnesia carbon bricks, carbon nanotubes or carbon nanofibers are in magnesia carbon bricks due to high cost, difficulty in dispersion, and structural alteration at high temperatures. The application in the middle has not been continuously studied.
