【作者】 纪文文；

【导师】 宋月鹏；

【作者基本信息】 山东农业大学 ， 机械设计及理论， 2010， 硕士

【摘要】 钇铝石榴石(简称YAG)透明陶瓷是近年来快速发展起来的重要的先进陶瓷材料,目前,YAG透明陶瓷成为国内外研究的热点,尤其在激光领域。但长期以来,该材料的制备技术一直沿用粉末冶金工艺流程,其制备周期长,生产成本高,质量难以保证。同时,由于陶瓷熔点高、盛装困难,且高温陶瓷凝固后形成粗大组织,很少有采用类似金属材料的熔融铸造工艺路线进行制备。基于此,本研究在中科院理化技术研究所成功研制出Al2O3透明陶瓷等的基础上,利用热力学分析、动力学分析、实验及仿真模拟等理论及技术手段对超重力燃烧合成透明YAG陶瓷进行了深入的研究,并得出较好的研究成果,具体包括以下内容。首先,本文在建立有关热力学数据库的基础上,根据热力学原理,使用VisualBasic语言编制了热力学数据计算系统,并对编程计算结果进行可靠性验证。通过对不同体系自蔓延高温合成绝热温度的计算结果与分析和体系优选应遵循的原则,进行合成YAG陶瓷体系的优化选择。结果显示,采用Al/NiO/Y2O3体系进行燃烧合成YAG陶瓷最为合适。其次,通过静态下合成YAG试验研究表明：铝热剂原料粒度和压块密度会对压块的燃烧速度产生一定影响,这点与文献(宋月鹏,2009)结论相同。超重力熔铸技术是将燃烧合成技术与超重力技术相结合,利用铝热燃烧合成体系的强放热获得超高温的陶瓷/金属混合熔体,并实现二者的彻底分离。在超重力场中进行燃烧合成YAG陶瓷实验的研究结果显示,陶瓷体内金属颗粒的含量、气孔的多少和各种晶格缺陷与超重力的大小、熔体存在的时间密切相关,进而影响到YAG陶瓷的透明度。最后,利用ANSYS有限元分析软件,对超重力燃烧合成过程的温度场和应力场进行模拟,并结合实验结果验证模拟结果的可靠性。通过对温度场有限元模拟结果结合绝热温度计算和试验数据,得出了重力系数对多相熔体分离及产物致密化的影响规律。应力场的模拟结果显示压块的尺寸和质量对陶瓷的应力场有很大的影响,且热应力随温度的降低而降低。更多还原

【Abstract】 Because of the important situation in the laser field, the Yttrium Aluminum Garnet (YAG) transparent ceramics, one of the advanced ceramic materials, has becomed a research hotspot at home and abroad. However, the powder metallurgy technical has been always mainly preparation method of YAG for a long time, which has so many defects such as long preparation time, high production costs, disguarantee quality and so on. At the same time, the high melting point of ceramics leads to liquid difficultly filling and thick organization formatting after high temperature solidification. Thereforce, it is very difficulty to prepare for the YAG by costing technique.It is reported that the Al2O3 transparent ceramics had been succeed to prepare by a new method-Combustion Synthesis under Ultra-high Gravity Field in Technical Institute of Physics and Chemistry of CAS. Based on this successful fact, some researches such as thermodynamic and kinetic analysis, simulation and experimental test and so on are carried on the YAG transparent ceramic in this paper. The results are lied on as follow:First of all, the thermodynamic database of materials is established. Combining with the common thermodynamic principle and Visual Basic language, a SHS system thermodynamic data calculation computer program is so obtained. And then, its reliability is verified by many ways. According to the adiabatic temperature of many SHS sytems, the thermite reaction system of YAG preparation is optimized by computer calculating. The results showed that the Al/NiO/Y2O3 thermite is the most appropriate system for YAG ceramic preparation.Secondly, the static experimental results of combustion synthesis show that the raw agents’facts such as sizes of aluminium powder and compact density have certain effect on combustion velocity. Melt-casting under ultra-high gravity integrates the combustion synthesis with ultra-high gravity technology. The ultra-temperature metal/ceramic mixing-melts can be achieved by heat generated from thermite combustion reaction. The ceramic product is separated in the ultra-high centrifugal field. The further researches show that the defects in YAG ceramic such as content of metal particles, the amount of pores and a variety of lattice defects are closely related to the magnitude of gravity and the existence time of melt, which can affect the transparency of YAG ceramic.Finally, the temperature and stress distribution during the combustion synthesis under ultra-high gravity were simulated and then were verified by ANSYS finite element analysis software. The experimental results agree very well with the simulation ones, which indicated the high reliability of this method. Combining with the adiabatic temperature calculation and experiments verification, the rules of the gravity coefficients effect on the separation of the multi-phase melts and on the densification of the products are so obtained. Furthermore, the stress field simulation results show that the size and quality of compacts have remarkable effects on the stress field of ceramics. And the thermal stress decrease along with system temperature decrease.更多还原