【作者】 田勃然；

【导师】 刘家臣；

【作者基本信息】 天津大学 ， 材料学， 2005， 硕士

【摘要】 异种陶瓷连接为不同的陶瓷材料在特种条件下共同发挥其特性提供了技术上的可能性,其意义可与焊接在金属间的连接相比拟,为多功能陶瓷制品的开发提供了广阔的前景。然而以往的陶瓷连接多集中在烧结体的连接。坯体连接是最近发展起来的,但是目前连接成功的例子多局限于单组分或属性相似组分的陶瓷坯体连接,而对于基体的物理性能如热膨胀系数差异较大的体系的陶瓷连接的研究很少。本论文研究了两种最常用的氧化物陶瓷—氧化铝和氧化锆之间的连接性能。连接采用工艺上最简单的注浆成形和坯体状态下直接连接的技术。实验表明由于氧化铝和氧化锆热膨胀系数的差别,两种坯体在烧结过程中,在界面附近产生了很大的残余应力,导致直接连接的失败。为了降低两侧的热膨胀系数差异导致的残余应力,连接中采用了梯度的概念,设计了三种由不同含量的氧化铝和氧化锆复合的中间层——75Al₂O₃/25ZrO₂,50Al₂O₃/50ZrO₂和25Al₂O₃/75ZrO₂,研究了各层之间的连接效果。实验中用三点弯曲法测得了连接体的弯曲强度,并用扫描电镜观测了连接界面的形貌。通过研究三种中间层以及氧化铝和氧化锆它们之间的连接情况,我们发现组分相近的基体,烧结后的坯体的连接成功率最大。而且通过梯度层的设计,大大提高了连接的强度,界面处不但没有明显裂纹和气孔缺陷,而且不同属性和大小的颗粒在界面处相互镶嵌,实现了界面上不同组分的逐渐过渡。本文分析了坯体梯度连接的异种氧化物陶瓷连接成功的原因。并分析了影响连接成功的关键因素,通过对比试验,找到了最佳的工艺条件。实验中还结合残余应力的分析和计算,对连接中产生的裂纹进行了探讨。因为不同梯度层的连接具有很高的连接强度和界面结构,这样就能通过若干梯度层把氧化铝和氧化锆连接起来。更多还原

【Abstract】 The joining of different ceramics has been a promising and dynamic field since it provides possibility of combining ceramics with different specialties to work in special circumstance which would definitely broaden the application of ceramics. It is a kind of technique which is comparable with the welding in metal area. Although there have been some successful experiments in green state joining of ceramics, there were limited in the area of joining ceramics with similar properties such as thermal expansion coefficients, sintering shrinkage et al. Therefore, joining dissimilar, oxide ceramics with different properties is truly challenging but necessary.Zirconia and Alumina are widely used in many fields because of their good properties. In order to join the two different matrixes together successfully, the slurry was carefully examined to achieve high plasticity which contribute a lot for the modeling and joining in the green state. The experiments showed that the direct joining of Al2O3 and ZrO2 is unsuccessful since the large residual stress induced by the difference of thermal expansion coefficient made the interface or the Al2O3 side near the interface cracked after sintering.In order to reduce the residual stress, three kinds of graded composite are designed to be joined between Al2O3 and ZrO2. It was found that the matrix was joined most successfully with the one which was most similar in component. So we examined the flexural strengths and the interfaces of Al2O3-75Al2O3/25ZrO2, 75Al2O3/25ZrO2-50Al2O3/50ZrO2, 50Al2O3/50ZrO2-25Al2O3/75ZrO2 and 25Al2O3/75ZrO2-ZrO2 (75 and 25 refer to the weight fraction of Al2O3 or ZrO2 in the composite). The flexural strength of each group was satisfactory since it was larger than the weak matrix in the joining. SEM microstructure analysis of interfaces between different joining parts showed that the particles in both interfaces closely inlayed and integrated each other with less deformation, cracks and pores. Therefore, we can join the Al2O3 and ZrO2 if there are some layers of graded composite inserted between them. At last, the influence of the shrinkage of matrix after sintering to the joining was examined.更多还原