【作者】 张立；

【导师】 肖国庆；

【作者基本信息】 西安建筑科技大学 ， 材料学， 2016， 硕士

【摘要】 AlB₂-Al₂O₃复合粉中的AlB₂可做为低碳MgO-C质耐火材料的新型抗氧化剂,Al₂O₃在高温下与低碳MgO-C质耐火材料中的MgO反应生成镁铝尖晶石（MgAl2O4）,可提高耐火材料的抗侵蚀性,所以AlB₂-Al₂O₃复合粉体在低碳MgO-C质耐火材料领域,具有潜在的应用前景。本文研究了以Al和B₂O₃粉为原料,采用自蔓延高温合成方法制备AlB₂-Al₂O₃复合粉体。利用热力学理论计算了Al-B₂O₃体系的绝热温度,并用差热-热重法分析了反应过程中的物理化学变化。采用X射线衍射仪、扫描电镜和能谱仪分析手段,探究了Al粉形状、Al粉粒度、原料配比对燃烧合成复合粉体产物相组成和微观组织的影响,并研究了化学炉辅助对自蔓延高温合成Al B2-Al₂O₃复合粉体相组成的影响。热分析结果表明:Al-B₂O₃体系绝热温度为2327 K,该体系发生的物理化学变化过程为:温度399 K时,B₂O₃吸热脱水;温度增加到723 K时,B₂O₃吸热熔化;继续增加温度到937 K时,Al熔化;温度升高至1131 K时发生Al和B₂O₃强放热效应的氧化还原反应,同时生成Al B2-Al₂O₃复合粉体。研究表明:Al-B₂O₃体系自蔓延高温合成产物为AlB₂、Al₂O₃以及残留的少量Al。分别研究了球状、不规则状、鳞片状Al粉对该体系燃烧合成产物相组成的影响,结果发现:以球状Al粉为原料,产物中AlB₂含量更高。进而研究了球状Al粉100目、300目及600目三种粒度对产物相组成的影响,结果表明:随着Al粉粒度的减小,自蔓延高温合成反应的最高燃烧温度提高,燃烧波速增大,复合粉体中AlB₂含量增加,当Al粉为600目时燃烧波速为2.08 mm/s,AlB₂和Al₂O₃含量最高。相对于理论配比,随着Al过量10%、20%、30%、40%,产物中Al₂O₃含量先增加后减少,在Al过量30%时达到最大值,AlB₂含量保持不变。采用Ti和C粉混合物为化学炉辅助自蔓延高温合成,结果表明:化学炉有助于促进反应的发生,有利于Al B2相的发育,相对Al过量30%的常规自蔓延高温合成,AlB₂和Al₂O₃含量增加。更多还原

【Abstract】 AlB₂-Al₂O₃ compound powders have potential application as additives in low carbon MgO-C refractory, because AlB₂ could act as antioxidant and Al₂O₃ could improve the corrosion resistance due to magnesium aluminate spinel which was generate by the reaction between Al₂O₃ and MgO. AlB₂-Al₂O₃ compound powders were prepared by combustion synthesis using Al and B₂O₃ powder as starting raw materials in this thesis. Based on thermodynamic theory, the adiabatic temperature（Tad） of Al-B₂O₃ system was calculated. The physical and chemical changes during the reaction were analyzed by differential thermal analysis and thermogravimetry（DTA-TG）. The product were characterized by X-ray diffraction（XRD）, scanning electron microscope（SEM） and energy dispersive spectrometer（EDS）, and the effects of particle size of Al powder, morphology of aluminum powder and raw material ratio on combustion parameters, phase composition and microstructure of final products were discussed. The influence of using chemical oven self-propagating high-temperature synthesis（C.O.SHS）in the phase composition of the AlB₂-Al₂O₃ compound powders were also focused on.The results of thermal analysis showed that the adiabatic temperature of Al-B₂O₃ system is 2327 K, the physical and chemical changes including lost of absorbed water when the temperature reaches 399 K, endothermic melting of B₂O₃ at 723 K, melting of Al at 937 K, the strong exothermic redox reaction between Al and B₂O₃ occurs at about1131 K, and finally forming of AlB₂-Al₂O₃ compound powders.The results showed the final synthesized products of Al-B₂O₃ system are AlB₂,Al₂O₃ and remained Al. The experimental results of phase composition of final product synthesized using spherical, irregular shape and flaky aluminum powder as raw material showed that the content of AlB₂ is the highest when the spherical Al was used as raw material. Different particle size of spherical Al was used as raw materials. The results show that the maximum combustion temperature, velocity of combustion wave spread increased, and content of AlB₂ in final product increased, with the particle size of Al decreasing. The velocity of combustion wave spread is 2.08 mm/s and the content of AlB₂ and Al₂O₃ is the highest, when the particle size of Al was 600 mesh.The content of Al₂O₃ in the product increases and then decreases with Al increasing comparing with that prepared by stoichiometric ratio. The content of Al₂O₃ is the highest, when the excessive amount Al is 30%.AlB₂-Al₂O₃ compound were prepared by C.O.SHS using Ti and C powder. It was showed that the C.O.SHS is favor for the growth of AlB₂, there are higher content of both AlB₂ and Al₂O₃, comparing with that prepared by SHS, when the excessive Al amounts of both SHS and C.O. SHS are 30%.更多还原