【作者】 陆洪彬；

【导师】 陈建华；

【作者基本信息】 南京工业大学 ， 材料学， 2006， 硕士

【摘要】 钛酸铝（AT）具有熔点高、热膨胀系数低、导热系数低、弹性模量低、抗热震和抗冲击性能优异等特点,但是存在热稳定性差和机械强度低的两大缺点,限制了其实际应用。钛酸铝—莫来石（MAT）复相陶瓷是将AT热膨胀系数低、抗热震性好的优点与莫来石机械强度、高温性能良好的特性相结合的一种新型高温材料,具有广阔的应用前景。注凝成型工艺是一种可制备高均匀性、高密度、复杂形状陶瓷制品的新型成型方法。采用干压法和注凝法两种成型工艺,在系统地研究添加剂MgO、SiO₂、Fe₂O₃对AT热稳定性影响的基础上,以稳定AT和工业莫来石为原料,制备了MAT复相陶瓷。通过测定其物理、力学、热学及高温性能,进行XRD和SEM分析,对其组成、工艺、结构及性能之间的关系进行了研究。采用注凝成型工艺制备AT的研究结果表明:研磨时间、分散剂、固含量对Al₂O₃-TiO₂注凝成型料浆的流变性能有重要影响。制备AT的最佳注凝成型工艺条件为:研磨时间4h,分散剂含量3%,固含量45%。对AT热稳定性的研究结果表明,MgO和Fe₂O₃作为添加剂均能够促进钛酸铝的合成和抑制其热分解,且MgO的效果优于Fe₂O₃。在一定范围内提高烧成温度和延长保温时间有利于钛酸铝的合成和提高其热稳定性。MgO-SiO₂、MgO-Fe₂O₃、Fe₂O₃-SiO₂复合添加剂均能够抑制钛酸铝的高温热分解,其效果优于单一添加剂。添加MgO 10 mol %和SiO₂15 mol %所制备的AT试样在1100℃保温50h后没有分解,即使在保温150h后,其分解率仅为9.5%。采用干压成型和注凝成型工艺制备MAT复相陶瓷。研究发现,干压成型的体积密度较高,抗弯强度和热膨胀系数较低;而注凝成型的体积密度较低,抗弯强度和热膨胀系数较高。注凝成型工艺制备的MAT复相陶瓷材料的抗弯强度最高达110.05MPa,而干压成型工艺制备的最高为65.45Mpa。干压成型MAT复相陶瓷的致密度较高,内部空隙较少。注凝成型MAT复相陶瓷的致密度稍低,但钛酸铝和莫来石颗粒分布均匀,结合良好。热震试验结果表明,MAT复相陶瓷材料抗热震性能优异。热震试验后,AT含量较低（≤20%）的MAT复相陶瓷的抗弯强度明显提高,而AT含量较高（30%）的MAT复相陶瓷有所降低。其原因在于,前者在热震过程中钛酸铝内部的微裂纹发生钝化,更多还原

【Abstract】 Aluminium titanate （AT） has characteristics of high melting point, low thermal expansion coefficient, low heat conductivity, low elastic ratio, excellent thermal shock resistance and shock resistance. But AT has two fatal defects of poor thermal stability and low mechanical strength, and its application was restricted. Aluminium titanate and mullite （MAT） composite ceramic is a kind of new high-heat material, which combines low thermal expansion coefficient and good thermal shock resistance merits of AT with good mechanical strength and high-heat performances of mullite,and has extensive applied prospect. Gelcasting process is a new molding method that can prepare high homogeneous, high density, complicated shape ceramic products.On the basis of the effects of MgO, SiO₂ and Fe₂O₃ additives on thermal stability of AT were systematically studied, and use stable aluminium titanate and industrial mullite as major raw materials, MAT composite ceramics were prepared by two molding process of drying and gelcasting. The relationships of performances dependence of composition, process and structure were investigated through measuring the physical, mechanical, thermal, and high-heat properties and analyzing XRD and SEM of MAT composite ceramics.The results of AT prepared by gelcasting showed that mill time, dispersant content and solid volume fraction have great influence on rheological behaviors of Al₂O₃-TiO₂ slurry. When the mill time was 4h, the additive of dispersant was 3%, and the solid volume content was 45%, this technological condition was optimal to prepare AT by gelcasting.Research on the stability of AT indicated that MgO and Fe₂O₃ used as additives could promote the synthesis of AT and restrain the decomposition of AT, moreover, the effects of MgO were better than Fe₂O₃. Multiple additives of MgO-SiO₂, MgO-Fe₂O₃, Fe₂O₃-SiO₂ all could restrain the high-heat thermal decomposition of AT, and multiple additives were superior to single additives on the effects of restraining thermal decomposition of AT. The test examples of AT, which were prepared by both adding 10mol% MgO and 15mol % SiO₂, didn’t decompose after 50h thermal retardation at 1100℃, and even after 150h thermal retardation the decomposition ratio was only 9.5%.更多还原