【作者】 孙志华；

【导师】 刘开平；

【作者基本信息】 长安大学 ， 材料学， 2006， 硕士

【摘要】 钛酸铝陶瓷是一种具有广泛应用前景的高熔点,高耐热震,接近于零的热膨胀系数,低的导热系数,低的密度,优越的耐蚀性,对铝和铁有良好的浇铸性等特点的高温结构材料。根据钛酸铝的不同特性有不同的应用。譬如汽车的引擎构件是利用其绝热性能好和熔点高;而由于它的高抗热冲击性和对熔融金属的低浸润性,又可以应用在有色金属铸造和玻璃制造业;高抗热震性则使它可以作为喷口内衬复式接头的材料。随着钛酸铝性能的不断改善,其应用将越来越广泛。但同时该材料也存在着两大致命弱点:一是晶体在各个晶轴方向上的差异很大,导致在冷却时产生大量微裂纹,机械强度很低:二是在750-1300℃区间易分解为金红石和刚玉相,失去了钛酸铝的优良性能,因而大大限制了这种材料的推广应用前景。本文对钛酸铝陶瓷的结构,热稳定性、热分解、热膨胀、机械强度以及影响它们的因素进行了综合阐述,并且通过液相法实验,以碳酸氢氨作沉淀剂的共沉淀法制备了钛酸铝陶瓷前驱体粉末,加入各种添加剂,在1550℃烧结,分析了制备过程中的各种影响因素;通过固相法加入各种添加剂,在不同温度烧结钛酸铝陶瓷,得出添加剂、温度以及其他因素对钛酸铝陶瓷性能的影响。引入添加剂后,由于阳离子进入钛酸铝晶格取代对Al³⁺和Ti⁴⁺,增大了钛酸铝的晶格常数c值,降低了钛酸铝晶格的畸变程度,使钛酸铝晶格趋于稳定,提高了钛酸铝的热稳定性。烧成温度及保温时间对材料性能有重要影响,选择适宜的烧成温度和保温时间可获得晶粒均匀,成份均一的瓷体。更多还原

【Abstract】 Aluminium titanate as a kind of new ceramic material has special capability as thermal expand coefficient which is close to zero, low transmit heat coefficient, high melting point, thermal shock resistance and thermal beat resistance. It’s high temperature resistance is the best of low expand materials at present. Aluminium titanate material is a kind of excellent material which has high melting point and low dilatability. According to aluminium titanate’s different properties, it can be used differently. Such as it can be used as vehicle’s engine component for it’s good thermal resistance and high melting point. As it has high thermal beat resistance and low soakage to melting metal, it can be used in colored metal found and glass industry. It is used as inner liner compound tie-in material. But the material has two fatal defects: one was that the crystal was very large anisotropy which made its mechanical strength very low because there was much crack in the material when it cooled. Another was that itwould be very easy to decompose into rutile and corundum between 750～1300℃, which made it lose the excellent properties. So its application was restricted.The paper makes an overview about the microstructure of AT, simply thermal stability, thermal decomposition, low thermal expansion, coefficient mechanical strength, as well as the factors that influenced the properties mentioned above. Nevertheless, the article stated the making method of the AT powder. The AT powder is prepared by co-precipitation method using NH₄HCO₃ as precipitator. The progress in the research of AT ceramic is the key and it is showed that the PH is playing an important role in the co-precipitation of AT .Meanwhile, methods used to suppress thermal decomposition and how to improve the mechanical strength are also discussed, especially, the influence of different additive, suchasMgO、Fe₂O₃、SiO₂ and ZrO₂ on the capability of AT ceramic are discussed. Aluminum titanate is well stabilized by introducing ferric oxide and compositing with mullite. Aluminum titanate received a thermal stress from mullite around it because their differences of structure and property. The aberration of aluminum titanate was not easy to happen, so the thermal stability of aluminum titanate was promoted. After ferric oxide was added, the lattice constant of c increased because Fe³⁺ and Si⁴⁺ replaced Al³⁺ and Ti⁴⁺, the aberrance extent of aluminum titanate decreased, crystal latice of aluminum titanate was made to be stable, and the thermal stability was promoted.The thermal expansion coefficient of aluminum titanate-mullite composite is containing. Sintering temperature is important to the final properties of AT ceramic. It can be obtained AT ceramic of crystal granularity uniformity and component equality at proper temperature and heat preservation time.更多还原