【作者】 赵国林；

【导师】 汪涛；

【作者基本信息】 南京航空航天大学 ， 材料加工工程， 2007， 硕士

【摘要】 本文以亚微米级立方相钛酸钡粉体为原料,采用放电等离子烧结技术在各种不同工艺条件下制备了钛酸钡陶瓷。首先,以烧结温度为1150℃的样品为例研究了SPS烧结陶瓷的脱碳工艺,发现在800℃下脱碳2小时即可基本除去烧结体内的碳污染。此外,在其它工艺条件相同时,分别研究了烧结温度、保温时间、升温速率和压力对烧结体微观组织和结构的影响。研究结果表明:烧结温度、保温时间是影响样品微观组织的主要工艺参数,升温速率次之,压力的变化对样品组织的影响最不明显。X-Ray、EDS和SEM分析表明,SPS烧结样品为纯净的、单一的四方相结构,没有第二相和其它成分的存在,所有样品的晶粒大小在3~10μm之间。TEM结果显示,烧结体整体上结构非常致密,分布均匀,晶粒间结合比较紧密,晶界平直洁净,无杂质元素存在。样品室温介电性能较好,室温介电常数均在2000以上,介电性能频率稳定性较好;样品介电、压电性能与其晶粒度密切相关,SPS技术可以通过各工艺参数的变化来控制烧结样品的晶粒度,从而实现对材料性能的控制。对样品进行击穿电压和压电系数的测试表明:烧结体内极其微量的游离碳元素对样品的压电性能仍然有较大的劣化作用,建议使用BN等涂料代替碳纸作为模具包覆填料。与常规烧结相比,SPS技术可以大大地缩短烧结时间,降低烧结温度,快速制备组织致密、均匀的材料,同时,在同等晶粒度情况下获得较好的介电性能。对SPS烧结的机理分析认为:脉冲电磁场效应和局部等离子体的产生是促进扩散和加速物质迁移,降低烧结温度,从而促进烧结的主要原因。更多还原

【Abstract】 In this paper, BaTiO₃ piezoceramic was prepared by Spark Plasma Sintering （SPS） under different processing conditions using submicron cubic BaTiO3 powder as raw material.Firstly, the decarburization process was conducted by taking the sample sintered at 1150℃as example, of which the result indicates that after being held at 800℃for 2 hours, the carbon pollution in the SPS-sintered body can be completely removed, whereas, the BaTiO3 ceramic exhibits a high density and homogeneous microstructure.Furthermore, the effects of sintering temperature, holding time and heating rate on microstructures were investigated respectively. It was found that sintering temperature and holding time are the main processing parameters in influencing the microstructures of samples; heating rate take second place, whereas the change of sintering pressure only makes little effect on microstructures of samples.According to X-ray, EDS and SEM results, all the samples prepared by SPS are pure tetragonal lattice without second phase and other components. The grain sizes are between 3 and 10 micron. TEM result of sintered ceramics demonstrates a compact and homogeneous microstructure. The grain boundaries are clean and straight without impurities.The room temperature dielectric properties of samples are better than those prepared by conventional sintering method. Due to the dielectric and piezoelectric properties of samples depend on the grain size strongly, as well as by using SPS technique the grain size of the sintered body can be controlled by changing the parameters including sintering temperature, holding time, sintering pressure and so on, therefore SPS provides a method to conveniently adjust the dielectric and piezoelectric behaviors of materials through grain sizes controlling.Testing of Breakdown voltages and piezoelectric coefficients indicates that even a small amount of free carbon in the sintered body can deteriorate the piezoelectric property. It was recommended that use BN paste as die filler instead of carbon paper.Compared to conventional sintering method, SPS can greatly reduce sintering time and sintering temperature in preparing dense and homogeneous materials, and especially provide better dielectric properties than those conventionally sintered in the same grain sizes. The mechanism of SPS process has been revealed that pulse electric/magnetic effect and sparking plasma are main causes for accelerating diffusion, promoting matter migration, decreasing sintering temperature and promoting sintering.更多还原