低温烧结硅酸镁陶瓷及其微波介电性能研究

发布时间：2018-06-07 18:32

  本文选题：硅酸镁(Mg_2SiO_4)陶瓷 + 烧结性能　； 参考：《陕西师范大学》2015年硕士论文

【摘要】：微波介电陶瓷目前是电介质材料研究中的一类热门材料,具有不同介电常数(εr)的微波介电材料在不同领域中各有所长,根据介电常数的不同,可以把微波介电陶瓷分为多种类型,其中低εr值的微波介电陶瓷材料是低温共烧陶瓷(LTCC)技术中的一类重点研究对象,但此类材料大都有较高的烧结温度,针对其中有优良微波介电性能的微波介质陶瓷,许多研究者投入大量的精力来改善它们的烧结性能和微波介电性能,以实现此类材料在通信领域的广泛应用,进而满足现代通信技术在各个领域的发展需求。硅酸镁(Mg2SiO4)陶瓷作为一种典型的低ε,微波介电陶瓷同样具有烧结温度高、难致密的特点,其本身良好的微波介电性能难以发挥,从而限制了其在LTCC等技术领域的使用。本文以Mg2SiO4陶瓷为研究对象,针对其烧结温度高,易生成第二相等问题,在参考已有文献的基础上制定实验方案,利用X射线衍射、扫描电子显微镜(SEM)以及微波网络分析仪等技术手段来研究不同工艺对Mg2SiO4微观结构、烧结性能和微波介电性能的影响,主要内容包括：(1)利用化学法合成Mg2SiO4粉体并制备其陶瓷,通过控制反应条件实现原料分子间的充分接触,在较低预烧温度(890℃)获得了以Mg2SiO4为主相的预烧粉体,通过不同的测试手段研究Mg2SiO4陶瓷的物相组成、显微结构和微波介电性能,XRD图谱分析结果显示：实验过程中一直伴有MgO存在,陶瓷样品的烧结温度区间在1350℃-1500℃,1475℃烧结的陶瓷表现出良好的微波介电性能：εr=6.34, Q×f=128000GHz,τf=-46ppm/℃。(2)采用传统固相法制备Mg2SiO4陶瓷,通过调控Mg/Si非化学计量比(Mg/Si=2.2.025.2.04.2.05)合成Mg2SiO4,使MgO适量增多,当Mg/Si=2.05时得到较纯物相的Mg2SiO4粉体,通过分析不同组分制备的Mg2SiO4陶瓷的性能,探究了物相组成对Mg2SiO4陶瓷微波介电性能的影响。结果表明：Mg/Si=2.05组分配比的陶瓷粉体在1350℃烧结的Mg2Si04陶瓷具有较好的微波介电性能：εr=5.67,Q×f=64800GHz,τf=-40ppm/℃。(3)在采用MgO:SiO2=2.05:1非化学计量比制备物相较纯Mg2SiO4粉体的基础上,添加氟化锂(LiF)来改善Mg2SiO4陶瓷的烧结性能,实验研究了LiF对该陶瓷烧结温度、微观形貌及微波介电性能的影响,实验结果显示,添加一定量的LiF可以使Mg2SiO4陶瓷的最佳烧结温度从1350℃降到950℃左右,并且陶瓷的介电常数εr和品质因数Q×f与LiF的添加量和烧结温度有关。添加4wt%LiF,在940℃烧结5h的陶瓷样品表现出良好的微波介电性能：εr=6.58,Q×f=132900GHz, τf=-57ppm/℃,且Mg2SiO4+4wt%LiF的陶瓷胚体可以与银粉在950-C的条件下实现共烧。(4)Mg2SiO4陶瓷具有负的谐振频率温度系数(tf值),在添加4wt%LiF降温的基础上,同时添加24wt%TiO2来调节陶瓷的tf值。通过XRD图分析发现在烧结过程中LiF、TiO2和Mg2SiO4之间发生了化学反应,具有较多的物相存在,微波介电性能测试和分析表明：添加24wt%TiO2可以将Mg2SiO4陶瓷的tf值调节近零,LiF作为烧结助剂可以降低陶瓷的烧结温度,使样品在950℃-970℃的烧结温区得到性能稳定的陶瓷,950℃烧结制备的陶瓷具有最佳微波介电性能：8,=7.44,Q×f=38400GHz,τf=0.37ppm/℃。近零的tf值可以使该陶瓷有更加广泛的应用价值。
[Abstract]:Microwave dielectric ceramics are currently one of the most popular materials in the research of dielectric materials. Microwave dielectric materials with different dielectric constant (R) have their own advantages in different fields. Microwave dielectric ceramics can be divided into various types according to the dielectric constant, and microwave dielectric ceramics with low R value are low temperature co fired ceramics (LTCC). However, most of these materials have high sintering temperature. In view of the microwave dielectric ceramics with excellent microwave dielectric properties, many researchers have invested a lot of energy to improve their sintering and microwave dielectric properties, so as to realize the wide application of such materials in the field of communication and to meet the present situation. Magnesium silicate (Mg2SiO4) ceramics, as a typical low epsilon, has the characteristics of high sintering temperature and difficult density, and its good microwave dielectric properties are difficult to play. Thus, the use of Mg2SiO4 ceramics in the field of LTCC technology is limited. This paper takes Mg2SiO4 ceramics as the research object. In view of its high sintering temperature and easy generation of second equal problems, the experimental scheme was formulated on the basis of reference literature. X ray diffraction, scanning electron microscope (SEM) and microwave network analyzer were used to study the effects of different processes on the microstructure, sintering properties and microwave dielectric properties of Mg2SiO4. The main contents included the main contents. (1) the Mg2SiO4 powders were synthesized by chemical method and their ceramics were prepared. By controlling the reaction conditions, the full contact between the raw materials was realized. The prefired powders with Mg2SiO4 as the main phase were obtained at the lower prefiring temperature (890 degrees C). The phase composition, microstructure and microwave dielectric properties of Mg2SiO4 ceramics, and the XRD atlas were studied by different testing methods. The results show that MgO has been accompanied by the presence of MgO, the sintering temperature range of ceramic samples at 1350 C -1500 C and 1475 C sintered ceramics showed good microwave dielectric properties: epsilon r=6.34, Q x f=128000GHz, tau f=-46ppm/ C. (2) the traditional solid-phase method was used to prepare Mg2SiO4 ceramics by controlling the non stoichiometric ratio of Mg/Si (Mg/Si=2.). 2.025.2.04.2.05) synthesis of Mg2SiO4, increase the amount of MgO, and get Mg2SiO4 powder of pure phase when Mg/Si=2.05. By analyzing the properties of Mg2SiO4 ceramics prepared by different components, the influence of phase composition on the microwave dielectric properties of Mg2SiO4 ceramics is explored. The results show that the ceramic powders of Mg/Si= 2.05 groups are sintered at 1350 degrees centigrade at Mg2Si04. The ceramics have good microwave dielectric properties: epsilon r=5.67, Q x f=64800GHz, tau f=-40ppm/ C. (3) on the basis of MgO:SiO2=2.05:1 non stoichiometry compared with pure Mg2SiO4 powder, lithium fluoride (LiF) is added to improve the sintering properties of Mg2SiO4 ceramics. The sintering temperature, micromorphology and microwave dielectric properties of LiF on the ceramics are studied experimentally. The experimental results show that the optimum sintering temperature of Mg2SiO4 ceramics can be reduced from 1350 to 950 C by adding a certain amount of LiF, and the dielectric constant epsilon R and the quality factor Q x f are related to the addition of LiF and the sintering temperature. The ceramic samples sintered at 940 C at 940 C show good microwave dielectric properties. : epsilon r=6.58, Q x f=132900GHz, tau f=-57ppm/ C, and Mg2SiO4+4wt%LiF ceramic embryo can be co fired with silver powder under the condition of 950-C. (4) Mg2SiO4 ceramics have a negative resonant frequency temperature coefficient (TF value). On the basis of adding 4wt%LiF cooling, the 24wt% TiO2 is added to regulate the ceramic TF value. During the process, the chemical reaction between LiF, TiO2 and Mg2SiO4 has a lot of phase. The microwave dielectric properties test and analysis show that the addition of 24wt%TiO2 can adjust the TF value of Mg2SiO4 ceramics to nearly zero. The sintering temperature of the ceramics can be reduced by LiF as the sintering agent, and the sample can be stable in the sintering temperature zone of 950 C -970. Ceramics prepared by sintering at 950 C have the best microwave dielectric properties: 8, =7.44, Q x f=38400GHz, tau f=0.37ppm/ C. The near zero TF value can make the ceramics more widely applied.
【学位授予单位】：陕西师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ174.1

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相关期刊论文 前1条

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