添加热氧化鳞片石墨对高炉炭砖显微结构和性能的影响

Impact of the Addition of Thermo-activated Graphite Flake on the Microstructure and Properties of Carbon Blocks for Blast Furnace

首先采用热氧化方法对鳞片石墨进行处理得到热氧化鳞片石墨,以部分取代高炉炭砖中电煅煤细粉的方式将热氧化鳞片石墨引入到高炉炭砖中,借助X射线衍射仪、场发射扫描电镜以及激光导热仪等研究了热氧化鳞片石墨的添加对高温焙烧后高炉炭砖物相组成、显微结构、导热系数和抗铁水溶蚀等性能的影响。结果表明:与鳞片石墨相比,热氧化鳞片石墨的氧化活化能低,具有更高的反应活性。添加热氧化鳞片石墨在高温下促进了炭砖基体内原位陶瓷相SiC晶须的生成,从而优化了炭砖的微孔结构,提高了炭砖的耐压强度、导热系数和抗铁水溶蚀性能;但是热氧化鳞片石墨添加量过大时,炭砖的导热系数提高不明显,并且小于1 μm孔的容积率和耐压强度降低。对比引入相同量的天然鳞片石墨试样,添加热氧化鳞片石墨的炭砖耐压强度、导热系数和抗铁水溶蚀性能更优。当热氧化鳞片石墨的添加量为6%~8%(质量分数)时,高炉炭砖的综合性能最优。

Thermo-activated graphite flakes was firstly prepared by conducting thermal oxidation on graphite flake, and then they were introduced into blast furnace carbon blocks by partial substitution of anthracite powder. The effect of thermo-activated graphite flake on phase composition, microstructure, thermal conductivity and hot metal erosion resistance of carbon blocks fired at elevated temperatures was investigated by means of XRD, SEM and Laser thermal conductivity meter, etc. It could be found from the result that thermo-activated graphite flakes exhibit lower oxidation activation energy compared with graphite flakes, indicating a higher reactivity of thermo-activated graphite flakes than that of graphite flakes. The addition of thermo-activated graphite flakes accelerated the formation of in-situ β-SiC whiskers, so as to optimize the microporous structure and enhance the cold compressive strength, thermal conductivity and hot metal corrosion resistance of carbon blocks. However, there was no significant improvement on thermal conductivity of carbon blocks with excessive addition of thermo-activated graphite flakes, accompanied by the reduction in volume ratio of pore with aperture less than 1 μm and cold compressive strength. Taking the specimens with the same amount of gra- phite flakes in comparison, carbon blocks with addition of thermo-activated graphite flakes are superior in cold compressive strength, thermal conductivity and hot metal corrosion resistance. The optimal comprehensive performance of carbon blocks appeared under the condition of adding the 6wt%-8wt% of thermo-activated graphite flakes.