催化燃烧合成CNTs/铝酸钙复合粉及对含碳浇注料性能的影响

Carbon containing castables have integrated advantages of convenient installation, excellent slag penetration/corrosion resistance and thermal shock resistance. Their research and development play a key role in steel metallurgy industry. However, the performance and application are limited by their poor aqueous wettability. In the present project, the CNTs/calcium aluminate composite powders would be originally synthesized by the method of transition metal catalytic combustion synthesis using Al powder, CaCO3 powder, Al2O3 powder and phenolic resin as raw materials. The in situ forming of CNTs would not only overcome the drawbacks such as foaming of castables, inhomogeneous distribution of carbon, and coating spalling of surface modification, surface coatings and pelleting methods used to improve the aqueous wettability of carbon, but also reinforced the strength and toughness of castables. Based on analysis of combustion thermodynamics, the mechanisms of catalytic assistant combustion synthesis would be investigated, and the regulatory mechanisms of length/diameter ratio, content and distribution of CNTs would be illuminated. The aqueous wettability characteristics of CNTs/calcium aluminate composite powders would be researched, and the influence of CNTs/calcium aluminate composite powders on the slag penetration/corrosion resistance, anti-oxidation and thermal mechanical properties of carbon containing castables would be revealed. The catalytic combustion synthesis principles of Al-CaCO3-Al2O3-phenolic resin system would be originally understood. The novel technical route and theoretical basis would be provided for development of carbon containing castables.

含碳耐火浇注料不仅施工方便，而且具有优异的抗熔渣侵蚀性与抗热震性，其研发对钢铁冶金工业意义重大。但碳与水润湿性差，限制了含碳浇注料性能的发挥与广泛应用。本项目创造性提出以Al粉、CaCO3粉、Al2O3粉、酚醛树脂为原料，采用过渡金属催化燃烧合成CNTs/铝酸钙复合粉，在铝酸钙中原位形成CNTs，可避免采用表面活性剂法、石墨表面涂覆法、造粒法改善碳与水润湿性存在浇注料发泡、碳分布不均、涂层易剥落的缺点，同时发挥CNTs的强韧作用。基于热力学与燃烧学分析，研究催化燃烧合成机理，阐明CNTs长径比、含量及分布状态的调控机制。研究CNTs/铝酸钙复合粉与水润湿及分散特性，揭示CNTs/铝酸钙复合粉对含碳浇注料抗熔渣侵蚀性、抗氧化性及高温力学性能的影响规律。本研究不仅可以深刻认识Al-Al2O3-CaCO3-酚醛树脂体系催化燃烧合成规律，还可为含碳浇注料的研制提供新的技术途径与理论基础。

含碳耐火浇注料由于具有施工简便、抗渣侵蚀性强、抗热震性能好的优点，其发展对高温工业意义重大。然而，天然鳞片石墨较差的水润湿性限制了含碳浇注料性能的发挥与广泛应用。本项目分别使用燃烧合成法与埋碳烧结法制备了铝酸钙粉体和纳米碳/铝酸钙复合粉体。对淬熄试样进行分区表征，结合热力学与燃烧学分析，研究了CaO2-Al-Al2O3体系燃烧合成铝酸钙的机理,发现反应开始时CaO2最先分解，产生的O2与熔融金属Al反应生成Al2O3并放出热量，促使CaO和Al2O3共熔形成CaO-Al2O3液相，最终铝酸钙从液相中析出结晶，揭示了燃烧合成铝酸钙的溶解-析出机制。研究了CaCO3部分取代CaO2对燃烧合成一铝酸钙纳米纤维的影响规律，发现随着CaCO3取代量的增加，纤维产量先增高后降低，当取代量为40%时产量最高，并同时提出了纳米纤维的VLS底部生成模型。以柠檬酸钙、氧化铝为原料，埋碳烧结制备了含原位碳铝酸钙水泥（CCAC），发现柠檬酸钙首先分解形成乌头酸钙，而乌头酸钙的热解产生了一部分原位碳与CaCO3以及CH4、CO2、CO等气体，CaCO3进一步与CH4反应使更多的原位碳产生。研究了CCAC与水润湿及分散特性以及CCAC结合浇注料性能，发现CCAC结合浇注料熔渣侵蚀深度与含炭黑的浇注料相比降低23.6%，原因是原位碳均匀弥散分布在铝酸钙结合剂基质中，可提高基质的抗渣侵蚀性能，提高刚玉骨料抗熔渣侵蚀能力。发现氯化铁催化剂可溶于柠檬酸水溶液与碳酸钙反应生成的柠檬酸二氢钙溶液中，实现分子水平的分散，使铝酸钙中原位生成长径比超过10的多壁碳纳米管。发现碳纳米管/铝酸钙水泥结合Al2O3-SiC-C铁沟浇注料1100℃热震后残余强度保持率达44%，明显高于商用Secar71水泥结合浇注料的34%。本项目的实施丰富了含原位碳铝酸钙水泥的制备技术与理论，促进了含碳浇注料新型结合剂的发展。项目资助发表SCI/EI/CSCD论文11篇，申请发明专利5项。培养硕士研究生9名，培养博士2名，在站博士后1名。并在项目进行过程中，于2016年9月20日成功承办第七届国际耐火材料学术会议。