微波加热陶瓷动态过程的数值模拟

本文结合中国科学院上海硅酸盐研究所高性能陶瓷开放实验室研制成功的小功率微波烧结陶瓷的实验装置,对微渡加热陶瓷棒的动态过程进行了数值模拟,建立起一个变物性,变内热源的二维传热数学模型,并对模型进行了求解计算。计算结果和实测数据基本吻合。利用本模型可求出不同物性参数和尺寸的陶瓷材料在不同微波加热功率下的升温速率和温度场的变化,为控制微波烧结陶瓷的温度及热应力提供了理论参数。     

羟基磷灰石的微波烧结

对羟基磷灰石的微波烧结进行了系统研究，确定了制备致密HAP生物陶瓷材料的最佳微波烧结工艺条件．通过XRD、SEM等手段研究了烧结温度和时间对HAP生物陶瓷的物相和显微结构的影响，测试了烧结收缩率和抗折强度．结果表明，微波烧结利于HAP陶瓷坯体的致密化，可以实现低温快速烧结，并提高陶瓷的机械强度；微波烧结对HAP的分解有促进作用，而且随着烧结温度升高和时间延长HAP分解程度增大．1200℃烧结30min的HAP陶瓷样品抗折强度最高，为（95．42±3．45）MPa，其主晶相为HAP和β-TCP．     

微波烧结ZTA陶瓷力学性能研究

选用微波烧结新工艺，对ＺＴＡ陶瓷力学性能进行了研究，获得了较传统烧结工艺优良的陶瓷力学强度和断裂韧性，同时，新工艺陶瓷体积显微结构。     

微波烧结BaTiO3陶瓷的微结构

本文报道了微波烧结ＢａＴｉＯ３陶瓷的初步研究结果。利用微波烧结的ＢａＴｉＯ３陶瓷、与常规烧结相比，其轴向收缩率显著地不同。采用ＳＥＭ观察其微观结构也与常规烧结有显著的差异。ＸＲＤ分析其结构为四方晶系，初步推断此现象与ＢａＴｉＯ３陶瓷在微波场中的取向生长有关。     

高性能微波陶瓷材料应用研究

利用化学方法制备出高纯亚微米级BaCO3,MgO，钽酸镁及纳米级钽镁酸钡粉体，解决了TaCl5溶解问题，通过原材料提纯及细化，粉体晶型控制，实现了高性能微波陶瓷原材料的国产化。采用搅拌球磨等静压成型，烧结后期热处理等工艺，研制出Q0值高，工作频率高，温度稳定性好的高性能钽镁酸钡微波陶瓷材料；突破了烧结过程中成分挥发，离子序化及杂相控制等关键技术，采用简化波法进行介质谐振器设计，配合机械精加工工艺制作的介质谐振器工作频率高，频率一致性好，互换性高。该项目研制的高性能微波陶瓷材料及高Q0介质谐振器已成功地得到应用，取得了良好的应用效果。     

羟基磷灰石的微波烧结

对羟基磷灰石的微波烧结进行了系统研究,确定了制备致密HAP生物陶瓷材料的最佳微波烧结工艺条件.通过XRD、SEM等手段研究了烧结温度和时间对HAP生物陶瓷的物相和显微结构的影响,测试了烧结收缩率和抗折强度.结果表明,微波烧结利于HAP陶瓷坯体的致密化,可以实现低温快速烧结,并提高陶瓷的机械强度;微波烧结对HAP的分解有促进作用,而且随着烧结温度升高和时间延长HAP分解程度增大.1 200℃烧结30 min的HAP陶瓷样品抗折强度最高,为(95.42±3.45)MPa,其主晶相为HAP和β-TCP.     

陶瓷的微波烧结

在介绍微波加热基本理论的基础上，以实例综述了微波烧结陶瓷工艺的特点以及微波频率，添加剂和感应器在微波烧结中的应用。     

2 450 MHz/5 kW改进的单模腔型微波烧结系统研制

分析了微波烧结的特点和原理,介绍了一种自制的改进的ＴＥ１０３单模谐振腔型微波烧结系统,给出了在该系统上微波烧结Ａｌ２Ｏ３陶瓷材料的实验结果。结果表明,该系统可同时实现三根尺寸为４０ｍｍ×６ｍｍ×６ｍｍ的陶瓷材料的微波烧结,是一种理想的微波烧结系统。     

常压烧结与微波烧结ZTA陶瓷性能

选择Al2O3-ZrO2系统,采用微波烧结及常压烧结两种工艺,分别对ZTA陶瓷的力学性能和摩擦性能进行了测试比较,简单分析了影响ZIT陶瓷摩擦性能的主要因素,微波烧结使陶瓷的烧结温度降低,致密度提高,摩擦因数增大,磨损量减小。     

微波烧结PTC BaTiO3陶瓷的工艺与性能研究

利用微波烧结这种新技术，进行了微波烧结ＰＴＣ ＢａＴｉＯ３陶瓷的研究，分析了烧结工艺性能的影响，并给出了实验结果和结论。     

常压烧结与微波烧结ZTA陶瓷性能

选择Al2 O3 -ZrO2 系统 ,采用微波烧结及常压烧结两种工艺 ,分别对ZTA陶瓷的力学性能和摩擦性能进行了测试比较 ,简单分析了影响ZTA陶瓷摩擦性能的主要因素 ,微波烧结使陶瓷的烧结温度降低 ,致密度提高 ,摩擦因数增大 ,磨损量减小     

纳米复相陶瓷的制备方法综述

纳米复相陶瓷是一种新型复合材料，它的综合性能相对传统陶瓷有了很大的提高。目前为止，纳米复相陶瓷粉体的制备方法主要有机械球磨、均相复合、非均相复合等，纳米复相陶瓷的烧结方法有无压烧结、热压烧结、热等静压烧结、放电等离子烧结、微波烧结等。对于纳米复相陶瓷而言，热等静压烧结、放电等离子烧结、微波烧结是比较理想的烧结方法。     

Kinetics mechanism of microwave sintering in ceramic materials

Based on the traditional sintering model incorporating the characteristic of microwave sintering, the ionic conductance diffusion mechanism in microwave sintering was studied. A flat-ball model was presented to describe the kinetics process in microwave sintering, and was applied to the sintering process of TZP and ZrO₂-Al₂O₃ ceramics. The results indicate that the shrinkage rate of materials in microwave sintering is proportional to t ^2/3 and r ^−4/3, respectively, where t is the sintering time and r is the particle radius. Whereas, the shrinkage rate of materials in conventional sintering is proportional to sintering time t ^2/5. Our model suggests that microwave sintering is faster than conventional sintering, which shows a good agreement with the experimental observation in sintering process of TZP and ZrO₂-Al₂O₃. Supported by the State Key Program of National Natural Science of China (Grant No. 50332010) and the National Key Technology Research and Development Program for Resource and Environment of China (Grant Nos. 2006BAB12B03, 2006BAB12B05)     

RESEARCH ON MICROWAVE SINTERING ALUMINA CERAMICS

This paper introduces the characteristic of microwave sintering,introduces and analyses the process of microwave sintering of the alumina ceramics, moreover, compared with the experiments of conventional sintering method. Based on the researcb, some results are obtained, and experimental basis for microwave sintering of ceramecs is put forwarrd.     

Microstructure and strength modification of relaxor ferroelectric ceramics through microwave sintering for multilayer capacitors

Relaxor ferroelectric ceramics with the composition of xPb( Mg_(1/3) Nb_(2/3)O_3-yPb (Zn_(1/3)Nb_(2/3)O_3-zPbTiO_3 was fast sintered in a 2.45 GHz microwave system. Microwave-sintered samples illustrate more rapid densification and much smaller grain size microstructure than eonventional sintered samples. Also the microwave processing significantly increases the dielectric strength and flexural strength of the relaxor so that its strength becomes comparable with modified BaTiO_3, and could obtain comparable dielectric properties in comparison with conventional sintering process. Microwave processing has many advantages for sintering of relaxor ferroelectrie ceramics used as multilayer capacitors.     

Low-temperature sintering and microwave dielectric properties of Li2MgTi3O8 ceramics doped with BaCu（B2O5）

The influences of BaCu(B₂O₅) (BCB) addition on sintering, microstructure and microwave dielectric properties of Li₂MgTi₃O₈ ceramics were investigated using X-ray diffractometry, scanning electron microscopy and microwave dielectric measurements. The experimental results show that a small amount of BaCu(B₂O₅) addition can effectively reduce the sintering temperature to 900 °C, and induce only a limited degradation of the microwave dielectric properties. Typically, the best microwave dielectric properties of ɛ _r=24.5, Q×f =24 622 GHz, τ _f=4.2×10⁻⁶ °C⁻¹ are obtained for 1.0% BCB-doped Li₂MgTi₃O₈ ceramics sintered at 900 °C for 3 h. The BCB-doped Li₂MgTi₃O₈ ceramics can be compatible with Ag electrode, which may be a strong candidate for low temperature co-fired ceramics applications.     

微波介质陶瓷材料的研制

研制了Ｔｉ－Ｚｒ－Ｓｎ系微波介质陶瓷材料．用该材料制成的１２００ＭＨｚ二级式介质滤波器，各项性能满足技术要求．讨论了提高这种材料性能的途径．     

多模腔双频微波烧结炉的设计

通过对微波发生器的合理选择、安装和微波场场型的特殊设计,克服了多模腔微波烧结炉中微波场均匀性差的缺点,使多模腔微波烧结炉达到了好的烧结效果并降低了成本。特殊的保温结构设计不但起到了节能的效果还扩大了微波烧结炉的适用范围。     

多模腔双频微波烧结炉的设计

通过对微波发生器的合理选择、安装和微波场场型的特殊设计，克服了多模腔微波烧结炉中微波场均匀性差的缺点，使多模腔微波烧结炉达到了好的烧结效果并降低了成本。特殊的保温结构设计不但起到了节能的效果还扩大了微波烧结炉的适用范围。