关键词： 无机-有机精细复合功能材料   压电陶瓷颗粒   热释电材料   二氧化硅   压电聚合物复 合驻极体材料   有机改性二氧化硅(ORMOSIL)凝胶纳米多孔材料   复合光学材料  

摘要： 无机-有机精细复合功能材料是近年来功能材料领域中的一个研究热点.这种新材料 集无机材料与有机材料的优点于一体,并相互弥补各自的弱点,通过交叉耦合还可能会产生新的物理效应,从而使其具有优良的物理性能.由于复合材料的性能优于单一组分,采用适当的制备工艺将具有特定功能的无机材料与有机材料进行复合,可以获得性能优良的无机- 有机精细复合功能材料.怎样才能制备出满足要求的高性能无机-有机精细复合功能醭材料 的制备工艺及其微结构与牧师性能的关系.它们压电陶瓷颗粒-聚合物复合热释电与压电材 料、二氧化硅-压电聚合物复合驻极体材料、有机改性二氧化硅(ORMOSIL)凝胶纳米多孔材料和半导体微晶掺杂ORMOSIL纳米复合光学材料.

关键词： Silicon nitride  

摘要： The use of self-reinforcement by larger elongated grains in silicon nitride ceramics requires judicious control of the microstructure to achieve high steady-state toughness and high fracture strength. With a distinct bimodal distribution of grain diameters, such as that achieved by the addition of 2% rodlike seeds, the fracture resistance rapidly rises with crack extension to steady-state values of up to 10 MPa.m(1/2) and is accompanied by fracture strengths in excess of 1 GPa. When the generation of elongated reinforcing grains is not regulated, a broad grain diameter distribution is typically generated. While some toughening is achieved, both the plateau (steady-state) toughness and the R-curve response suffer, and the fracture strength undergoes a substantial reduction. Unreinforced equiaxed silicon nitride exhibits the least R-curve response with a steady-state toughness of only 3.5 MPa.m(1/2) coupled,vith a reduced fracture strength.

关键词： C10   E06   I05   N01   R02   V01  

摘要： The impact of solid transmutant generation and temperature transients during irradiation are new research subjects for application of fission neutron irradiation data to fusion materials development. Fundamental research for these issues is in progress, and includes such approaches as alloying the transmutant elements before irradiation and varying temperature irradiation with charged particles. In addition, novel uses of fission reactors are under way using neutron spectral changes to control solid transmutation, and highly controlled periodically-variable temperature irradiation. The understanding of microstructural processes in such complex and the variable irradiation conditions is growing. (C) 1998 Elsevier Science B.V. All rights reserved.

关键词： cement paste   silica fume   microstructure   small-angle scattering  

摘要： The effects on the microstructural development of adding silica fume to cements and concretes during cement hydration have been studied using small-angle neutron scattering and ultrasmall-angle X-ray scattering. A previously developed fractal based microstructural model has been applied to extract representative microstructural parameters from the small-angle scattering data. A link has been established between the existence of coarse or agglomerated particles in the silica fume particle size distribution and possible deleterious microstructural evolution during cement hydration. Published by Elsevier Science Ltd.

关键词： 氧化锆陶瓷   显微结构   力学性能   缺陷  

摘要： 为提高以ＺｒＯ２为主要成分的陶瓷水口新材料的力学性能，延长水口的使用寿命，用电子显微分析方法研究了材料的显微结构特征，提出材料的显微结构对力学性能的影响因素。认为晶粒大小是影响材料力学强度的主要因素，层错、位错缺陷的存在，可以提高材料的断裂韧性。并探讨了稳定剂对材料烧结温度的影响。

关键词： 微结构效应   流动应力   微观变形   复合材料   碳化硅  

摘要： 研究了在动态压缩时２１２４Ａｌ／ＳｉＣｐ复合材料的变形行为与微结构效应．分析结果表明，对于给定材料，复合材料的流动应力主要取决于微结构尺度效应．若增强相尺寸，基体晶粒尺寸以及增强相间距三者大小相当，则复合材料的流动应力取决于增强相的分散程度和位错密度；若增强相尺寸及其间距大小相当，但比基体晶粒大得多，那复合材料的流动应力主要取决于增强相的分散度．微观观测发现在同样加载条件下，变形局部化更容易在含较小碳化硅颗粒的复合材料内形成；变形区内的微损伤几乎都是基体与粒子界面脱粘和粒子角点邻近的微裂纹．对于所研究的这类复合材料，弹性模量及应变硬化几乎不受增强颗粒尺寸影响．

关键词： 振动陀螺   微机械陀螺   微机械加工   微结构设计   制造工艺  

摘要： 本论文研究出了我国第一个振动轮式微机械陀螺(MMG)的模型样机。文中重点阐述了微结构设计和制造工艺以及设计与工艺同步改进的过程。\n 1.按照振动形式分类，推导了目前存在的几种主要的MMG结构的动力学方程和灵敏度公式。经过全面分析和比较后，选择了振动轮式微结构，并依据制造工艺条件，确定了本MMG的总体方案。进一步依据有限元模态仿真结果，进行了结构参数设计并估算了预期的性能指标。此外，提出了驱动回路的锁相环自激振荡方案和检测回路的力平衡反馈控制方案。\n 2.研究了微结构的制造工艺——体硅溶解薄片法，并分硅片工艺、玻璃片工艺和组合片工艺讨论了整个工艺流程。重点研究了两项工艺专题：高深宽比硅槽的刻蚀和硅——玻璃静电键合。在第一个专题中，探讨了Cl基等离子和F基等离子对硅的刻蚀特性，在代用设备ICP790上探索出了分别用CCl2F2/O2和SF6/O2混和气体刻蚀高深宽比(5：1～7：1)硅槽的技术。在第二个专题中，自建了静电键合台，考察了本系统的温度特性，针对研究结果，改善实验参数，解决了多次流片中出现的键合强度较差和接触电阻较大的问题，并解释了自建系统与正规系统的差异，本键合台与光刻机配合使用，成功地实现了静电键合这一工序。\n 3.

关键词： SHS法   尖晶石   显微结构   原料   耐火材料  

摘要： 自变燃法（简称SHS：Self-propagatingHightemperatureSgnthesis）合成MgO－MgO·Al2O3耐火材料是一种新的工艺方法。岩相分析证明：该方法合成的材料具有大颗粒方镁石＋中颗粒方镁石＋铬和尖晶石交织气孔构造。反应合成的尖晶石将方镁石包裹起来，使材料具有更好的使用性能。

关键词： SiAlON   SiCnp   复合材料   力学性能   显微结构  

摘要： 本文采用机械混合Ｓｉ３Ｎ４，ＡｌＮ，Ａｌ２Ｏ３，Ｄｙ２Ｏ３和纳米β－ＳｉＣ粉料，通过热压烧结，制备了１０ｗｔ％纳米ＳｉＣ颗粒增强α－ＳｉＡｌＯＮ复合材料。力学性能测试表明，在室温时复合材料的维氏硬度，压痕断裂韧性和三点弯曲强度比单相α－ＳｉＡｌＯＮ略高。但复合材料的三点弯曲强度可以保持到１０００℃，其值为这时单相α－ＳｉＡｌＯＮ的两倍。断口形貌表明复合材料的晶粒尺寸比单相α－ＳｉＡｌＯＮ的小，这两种材料的室温断裂方式均以穿晶断裂为主。研究表明，低粘度的玻璃相是造成单相α－ＳｉＡｌＯＮ高温性能下降的主要原因，而纳米ＳｉＣ的加入可以促使晶界相结晶，从而使复合材料的高温性能维持到较高的温度。

关键词： meso-scale modeling   multiple-scale modeling   Voronoi cell finite element method  

摘要： This paper presents an overview of physically motivated computational models that are developed to link quantitative metallography, meso- and multiple-scale analysis for discretely reinforced non-uniform composites. Three-dimensional microstructure models are constructed by serially arranging the digitally acquired section micrographs obtained through serial sectioning. Characterization studies using spatial correlation, intensity and distribution functions show significant differences between 2D and 3D images. Mesoscopic analyses for particle damage by cracking and splitting are carried out in 2D by the Voronoi cell finite element method (VCFEM) and validated against experimental observations. Finally, the microstructural VCFEM is coupled with structural analysis models to concurrently predict evolution at macroscopic and microscopic scales. (C) 1998 Elsevier Science S.A. All rights reserved.