高炉用电煅煤基炭砖中高导次生相形成机理及其铁水溶蚀行为研究

The quality of carbon blocks is the decisive factor for the serve life of blast furnace. High thermal conductivity, high micro-pore rate and high molten iron corrosion resistance become the development direction of carbon blocks to fulfill the requirements of the longevity of blast furnace. However, it is difficult to get electric-calcined anthracite based carbon blocks with high thermal conductivity and high molten iron corrosion resistance simultaneity. Focus on above attention, the catalysis of binder and in situ reduction technology of TiO2 will be adopted in the preparation of carbon blocks, and the secondary phases such carbon nano-tubes, SiC and Ti (C, N) will play important roles in constructing of thermal network, reducing the thermal resistance between the different phases, and improving the interfacial characteristics between carbon block and molten iron. In this project, the catalyst loading in the surface of low thermal conductivity phases such as anthracite and corundum and the physical and chemical conditions for in situ formation of carbon nano tubes/lines in the composite materials will be investigated; the formation of silicon carbide whisker and graphite-silicon carbide heterostructure will be investigated, and the mechanism of constructing of high conductivity network will be discussed; the molten iron corrosion behavior of the composite materials with the direct introduction of TiO2 fine powders will be investigated, and the formation mechanism of Ti(C, N) and the effect of their content and distribution on the interfacial characteristics between carbon block and molten iron will be studied, which provide theoretical guidance for the preparation of carbon blocks with high thermal conductivity, high molten iron corrosion resistance and long service life for blast furnace.

炭砖寿命决定着高炉一代炉役。为满足高炉长寿要求，高导热、高微孔化率和高抗蚀已成为炭砖的发展方向。针对目前电煅煤基炭砖存在导热性与抗铁水溶蚀性难以兼顾的问题，拟在炭砖制备过程中采用结合剂催化、碳源活化及原位还原TiO2技术，充分发挥原位形成次生碳、SiC和Ti(C, N)等的作用，在材料中构建连续的高导网络、减少组分间的界面热阻，改善炭砖与铁水的界面特性，以期同时实现炭砖的高导热和高抗蚀。项目拟系统研究电煅煤和刚玉等低导相的表面改性及其过渡金属元素催化剂的负载，探明高温复杂环境下低导原料表面原位形成碳纳米管/线所需物理化学条件；研究材料中SiC晶须及石墨-SiC异质结构的形成，探明构筑纳米碳-高导陶瓷相协同导热网络所需物理化学条件；研究炭砖中Ti(C, N)的原位生成及其对炭砖铁水溶蚀行为的影响，探明原位形成合适的炭砖/铁水界面所需的物理化学条件，为开发高导热、高抗蚀、长寿命炭砖提供指导。

本项目针对电煅煤基炭砖存在的导热系数低、铁水溶蚀性能有待改善的问题，研究了电煅煤骨料表面催化剂的负载以及热处理温度对电煅煤表面生长纳米碳的影响，分析了电煅煤与原位纳米碳之间的界面特征；研究了电煅煤的活化处理方式对其表面碳化硅晶须生成的影响；研究了负载催化剂骨料和活化处理骨料、沥青粉、热氧化鳞片石墨和超细石墨的引入对炭砖中原位陶瓷相生成及其导热性能、微孔化程度的影响，探讨了炭砖内部原位形成纳米碳/碳化硅晶须以及石墨-碳化硅异质结构所需物理化学条件；研究了炭砖中Ti(C, N)的原位生成，分析了电煅煤骨料浸渍处理及其临界粒度的减小对炭砖显微结构和抗铁水溶蚀性能的影响。研究结果表明，在电煅煤骨料上负载含镍催化剂，可以在骨料表面催化生长结合良好的碳纳米管；热氧化和微波活化处理电煅煤，均可以提高其石墨相含量和反应活性，有利于在其表面生成大量晶须；在炭砖中引入活化处理骨料、催化剂以及活性碳源，可以大量生成碳化硅等陶瓷相，引入的热氧化鳞片石墨有利于形成石墨-碳化硅异质结构，并形成连续的石墨-高导陶瓷相导热网络，大幅度提高了炭砖的导热系数和微孔化程度。对电煅煤骨料进行真空浸渍氧化铝浆体处理可以提高骨料的致密度，降低电煅煤骨料的临界粒度有利于形成陶瓷包裹电煅煤结构；这两种途径均可以增加炭砖与铁水间的润湿角，提升了炭砖的铁水溶蚀性能。本项目通过电煅煤骨料表面生成纳米碳或碳化硅晶须改善骨料与基质之间的界面结合来降低其界面间热阻，在炭砖中引入活性碳源、TiO2和含镍催化剂构筑纳米碳-高导陶瓷相协同高导热网络，显著提高了炭砖的导热系数和微孔化程度；通过强化骨料、基质中大量形成高抗蚀陶瓷相以及构建陶瓷包裹电煅煤结构，大幅改善了炭砖的抗铁水溶蚀性能。相关研究成果可以为开发高导热、高抗蚀、长寿命炭砖提供指导，也可以为含碳耐火材料的强韧化和其他耐火材料导热性能和抗侵蚀性能的提升提供借鉴。