【作者】 张巍；

【导师】 韩亚苓； 孙泰礼；

【作者基本信息】 沈阳工业大学 ， 材料学， 2008， 硕士

【摘要】 本课题针对普通陶瓷热电偶保护管耐急冷急热性差,很容易断裂这一问题,对氧化铝陶瓷进行了改进,以提高氧化铝陶瓷的抗热震性。在实验过程中采用以Al₂O₃为基的纳米陶瓷粉料,再分别加入适量的堇青石、钛酸铝和锂霞石等粉料。通过混料、成型、排塑、烧结等工艺制备出Al₂O₃基纳米复相陶瓷。成型工艺采用干压成型和冷等静压成型技术,烧结工艺为无压烧结。通过实验确定了制备Al₂O₃—堇青石复相陶瓷、Al₂O₃—钛酸铝复相陶瓷和Al₂O₃—锂霞石复相陶瓷的最佳工艺,以及合成堇青石和锂霞石的最佳合成工艺。从XRD检测结果可以看出,合成堇青石的最佳工艺为:最高合成温度为1400℃,保温2h,降温速度为0.8℃/min;合成锂霞石的最佳工艺为:最高合成温度为1310℃,保温2h,降温速度为0.8℃/min。采用SEM对陶瓷进行组织结构分析,发现氧化铝—堇青石复相陶瓷中形成长柱状颗粒,互相连接的长柱状颗粒能较好地抵抗由于热震引起的裂纹的扩展,使材料的抗热震性能大大改善;在Al₂O₃—钛酸铝复相陶瓷中,存在大量的强化相颗粒,这些强化相颗粒镶嵌在基体上,可以阻止裂纹的扩展,有效的缓解了热应力,因此提高了材料的抗热震性。结果表明:堇青石加入量w（堇青石）=10%,烧结温度为1520℃时,陶瓷样品能够承受1500℃温差（空冷）的热震破坏,并且是制备Al₂O₃—堇青石复相陶瓷的最佳工艺;钛酸铝加入量w（钛酸铝）=20%,烧结温度为1510℃时,陶瓷样品能够承受1500℃温差（空冷）的热震破坏,并且是制备Al₂O₃—钛酸铝复相陶瓷的最佳工艺;锂霞石加入量w（锂霞石）=20%,烧结温度为1500℃时,陶瓷样品能够承受钢水中1500℃温差（空冷）的热震破坏,并且是制备Al₂O₃—锂霞石复相陶瓷的最佳工艺。更多还原

【Abstract】 This project is to study the method of improving the thermal shock resistance of alumina ceramics,because the tube for protecting thermocouples which is made of common ceramics bears the quick cooling and heating badly,splits very easily.In the experiment,Al₂O₃ powder is the basic material of nano-composite ceramics. We added appropriate amount of other kinds of powder,such as cordierite,aluminium titanate and eucryptite.The progress of making alumina matrix ceramics can be divided into mixing,shaping,discharging plastic and sintering,etc.In the process of shaping and sintering,dry pressing,isostatically pressing shaping technology and pressureless sintering technology were used respectively in the experiment.After the experiment,we determined the material gradient and the best technical process of alumina-cordierite mullite ceramics,alumina-aluminium titanate mullite ceramics and alumina-eucryptite mullite ceramics.In addition,the best synthesis technical of cordierite and eucryptite was also determined.Results of XRD show that the best synthesis technical of cordierite is synthesis temperature is 1400℃,heat preservation time is 2h,cooling rate is 0.8℃/min;The best synthesis technical of eucryptite is synthesis temperature is 1310℃,heat preservation time is 2h,cooling rate is 0.8℃/min.The microstructure of ceramics was observed in SEM.It was founded that the solid solution has formed in the matrix of alumina-cordierite mullite ceramics,and it looks as the shape of long strip distributing without any orderliness.It is effective to abate thermal stress and raise the strength of ceramics for such microstructure,and it is one of the most important reason that the properties of thermal shock resistance of the ceramics can be improved effectively.There are a lot of strengthened grains in the alumina-aluminium titanate mullite ceramics,these grains bond in the matrix so that they can prevent the expansion of crack and abate thermal stress effectively,and it is one of the most important reason that the properties of thermal shock resistance of the ceramics can be improved.The results show that when the amount of additive cordierite w（cordierite）=10%and the sintering temperature is 1520℃,the ceramics can endure the thermal shock with a temperature difference of 1500℃（cooling in air）,and this is the best component of alumina-cordierite ceramics.When the amount of additive aluminium titanate w（aluminium titanate）=20%and the sintering temperature to be 1510℃,the ceramics can endure the thermal shock with a temperature difference of 1500℃（cooling in air）,and this is the best component of alumina-aluminium titanate ceramics.When the mount of additive eucryptite w（eucryptite）=20%and the sintering temperature is 1500℃,the ceramics can endure the thermal shock with a temperature difference of 1500℃（cooling in air）,and this is the best component of alumina-eucryptite ceramics.更多还原