高压烧结硅酸镁陶瓷及其微波介电性能研究

发布时间：2018-01-29 11:55

  本文关键词： MgSiO3 介电常数 品质因子 高压烧结 抗弯强度　出处：《武汉理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：本文的主要研究目的是探索高压制备微波介电陶瓷的新方法。通过对介电陶瓷研究现状的调研,提出以硅酸镁(MgSiO3)微波介电陶瓷的快速烧结作为本文的研究内容。实验以氧化镁(MgO)和二氧化硅(SiO2)为原料、国产六面顶大腔体液压机为实验平台。在烧结实验之前,对六面顶大腔体液压机的腔体压力和温度进行了标定,并且与已有的标定结果进行了对比,证实了腔体压力和活塞直径之间存在平方正比关系。选择不同的烧结压力、温度和时间,制备了七组MgSiO3介电陶瓷。对陶瓷样品进行了密度、XRD、SEM、介电参数和力学特征测量,结论如下:1.在选择合适的压力和烧结温度的前提下,几分钟之内即可实现陶瓷体的烧结;在高压烧结过程中,MgSiO3可能发生结构相变。常压下制备的MgSiO3属于单斜晶系,当压力在4GPa、烧结温度高于1100℃时,MgSiO3转变为正交晶系;2.烧结温度的升高和时间的延长,都可以促进MgSiO3晶粒的生长,提高烧结压力的作用则恰好相反。晶粒越小陶瓷体的密度和抗弯强度越大;3.高压烧结的MgSiO3介电陶瓷,其介电常数最低值为6.7,达到了微波介电陶瓷的特性要求,并且烧结体具备较好的力学强度;4.烧结体晶粒较大、密度较高时烧结体介电常数较小,品质因子相对较高。由于晶粒的异常生长导致晶粒分布不均匀,晶粒间结合情况发生变化,品质因子增大的同时随频率的波动也会更加明显。本文借助高压设备,在极短时间内烧结出高致密度的MgSiO3陶瓷,一方面表明高压作为辅助条件可以极大程度地提高烧结效率,为介电陶瓷的制备提供了新的参考方法,另一方面也表明在微波频段(K波段)MgSiO3陶瓷的介电损耗相对较大,在Mg-Si-O体系的微波介电陶瓷烧结过程中,应当尽量避免MgSiO3的形成。
[Abstract]:The main purpose of this paper is to explore a new method for preparing microwave dielectric ceramics at high voltage. The rapid sintering of MgSiO _ 3 microwave dielectric ceramics is proposed as the research content in this paper. The materials of the experiment are MgO _ (2) and Sio _ (2). Before the sintering experiment, the pressure and temperature of the chamber were calibrated, and the results were compared with the existing calibration results. It is confirmed that there is a square proportional relationship between cavity pressure and piston diameter. Seven groups of MgSiO3 dielectric ceramics were prepared by selecting different sintering pressure, temperature and time. SEM, dielectric parameters and mechanical characteristics are measured. The conclusions are as follows: 1. Sintering of ceramic body can be realized in a few minutes under the premise of selecting appropriate pressure and sintering temperature; The MgSiO3 prepared under normal pressure belongs to monoclinic system. When the pressure is 4 GPA, the sintering temperature is higher than 1100 鈩，

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