SiCp／Si3N4复合材料的低温冷处理与强韧化

研究了ＳｉＣｐ粒径与ＳｉＣｐ／Ｓｉ３Ｎ４复合材料的抗弯强度和断裂韧性之间的关系，详细探讨了低温冷处理对材料性能的影响。研究结果表明，ＳｉＣｐ颗粒增加粒径范围为３０～５０μｍ增强的粒径范围为〈２５μｍ，低温冷处理不仅可以进一步提高强度和韧性，而且可以改变增韧的粒径范围，使增韧和增强的粒径范围部分重合，这为正确材料的强韧化设计和合理制定强韧化工艺提供了依据。     

TiC／Si3N4导电陶瓷复合材料的制备

通过气压烧结工艺制备了含１,５,２０,２５,３５ｗｔ％ＴｉＣ的Ｓｉ３Ｎ４陶瓷复合材料研究了其导电特性,该复合材料由充当绝缘体的Ｓｉ３Ｎ４和作为导电添加剂的ＴｉＣ组成,其电阻率主要取决于其中的ＴｉＣ含量。复合材料的渗流阈值ＶＣ为１６．４５－１８．５０ｖｏｌ％,当ＴｉＣ含量达到或超过该阈值时复合材料中就形成导电通路,电阻率迅速降低。     

稻壳制备SiC晶须及其Si3N4陶瓷复合材料的应用

本文对稻壳合成ＳｉＣ晶须进行了研究，生产了三种ＳｉＣｗ，并进行了复合Ｓｉ３Ｎ４陶瓷材料的研究。     

Si3N4／Si3N4陶瓷连接的研究进展

连接技术是Ｓｉ３Ｎ４陶瓷实用过程中必须解决的难题之一。本文综述了Ｓｉ３Ｎ４／Ｓｉ３Ｎ４陶瓷连接的研究现状以及不同连接工艺对连接强度的影响。     

TiN对Si3N4复合材料力学性能及电导率的影响

研究ＴｉＮ粒子对氮化硅材料力学和电导率的影响,发现ＴｉＮ粒子的引入,对基体材料能起到增韧补强的作用;在烧结过程中,ＴｉＮ和Ｓｉ３Ｎ４发生互熔,当ＴｉＮ粒子达到一定比例后,复合材料内形成导电网络,材料具有电导性。     

定向排布的SiC晶须补强Si3N4复合材料的制备

通过挤制成型和热压烧结成功地制备了具有很好的一维定向排布的ＳｉＣ晶须补强Ｓｉ３Ｎ４复合材料，并从力学上分析了挤制成型过程中流体的受力状态，使晶须定向排布的原因以及影响晶须定向度的因素。     

ZrO2纤维—ZrO2微粉—Si3N4基陶瓷复合材料的研究

采用高速搅拌、超声分散的湿法混合工艺制备出无规则取向ＺｒＯ２短纤维热压Ｓｉ３Ｎ４陶瓷复合材料。对复合材料的强度及韧性进行了研究，采用ＴＥＭ技术对材料的微观结构进行了分析。     

SiC晶须及原位增强Si3N4基复合材料的断裂过程

探讨了ＳｉＣ晶须增强和β－ｓｉａｌｏｎ细长晶粒原位增强Ｓｉ３Ｎ４基复合材料的断裂过程。２种材料的试验结果都显示出明显的二级增韧行为：一级增韧过程,断裂阻抗ＫＲ随微小的裂纹扩展而急剧增大,大裂纹扩展到大约０．２５ｍｍ时达到饱和;二级增韧过程,ＫＲ缓慢增长,一直持续到裂纹扩展达到１ｍｍ（原位增强）和１．８ｍｍ（晶须增强）,观察和分析表明：二级增韧行为的发生,本质上起因于裂纹尖端后方桥接晶须和细长晶粒与     

耐高热环境氮化硅基复合陶瓷头罩的研究现状

介绍了国内外耐高热环境氮化硅基复合陶瓷头罩材料的研究进展及应用情况,简要地介绍了氮化硅基复合陶瓷头罩研制过程中的关键技术。     

刚玉-氮化硅复合材料研究现状

分析了陶瓷杯的损毁机理及陶瓷杯耐火材料的发展。重点总结了目前刚玉-氮化硅复合耐火材料的研究现状。     

Seamless Joining of Silicon Nitride Ceramics

High-strength joining of Si₃N₄ ceramics has been achieved by developing a process that effectively eliminates the seam, and may allow for fabrication of large or complex silicon nitride bodies. This approach to joining is based on the concept that when sintering aids are effective in bonding individual grains, they could be equally effective in joining bulk pieces of Si₃N₄. Optimization of the process led to Si₃N₄/Si₃N₄ joints with room-temperature bend strengths as high as 950 MPa, corresponding to more than 90% of the bulk strength of the Si₃N₄. At elevated temperatures of 1000° and 1200°C joint strengths of 666 and 330 MPa, respectively, were obtained, which are the highest values reported to date for these temperatures. These bend strengths are also more that 90% of the strength of bulk Si₃N₄ measured at these temperatures.     

Elevated-Temperature Mechanical Properties of Silicon Nitride/Boron Nitride Fibrous Monolithic Ceramics

A unique, all-ceramic material capable of nonbrittle fracture via crack deflection and delamination has been mechanically characterized from 25° through 1400°C. This material, fibrous monoliths, was comprised of unidirectionally aligned 250 μm diameter silicon nitride cells surrounded by 10 to 20 μm thick boron nitride cell boundaries. The average flexure strengths of fibrous monoliths were 510 and 290 MPa for specimens tested at room temperature and 1300°C, respectively. Crack deflection in the BN cell boundaries was observed at all temperatures. Characteristic flexural responses were observed at temperatures between 25° and 1400°C. Changes in the flexural response at different temperatures were attributed to changes in the physical properties of either the silicon nitride cells or boron nitride cell boundary.     

氮化硅复合材料的研究进展

简述了氮化硅的结构、性质和粉体制备,综述了近年来氮化硅基复合材料的研究进展。     

低成本制备氮化硅材料的研究

采用工业用纯净水作分散介质,制备了氮化硅陶瓷试样。并对试样进行了力学性能的测试,结果表明其常温力学性能指标略低于用酒精作分散介质材料的试样,断裂韧性为6.42MPa·m~(1/2),硬度为1522kgf·mm~(-2),证明了这种材料在常温下是可以使用的。     

氮化硅陶瓷在现代制造业中的应用

本文论述了氮化硅结构陶瓷材料的性能,着重介绍了此种材料在国内外制造业中的应用现状,也讨论了氮化硅陶瓷的缺陷及研究方向。     

Silicon Carbide Monofilament-Reinforced Silicon Nitride or Silicon Carbide Matrix Composites

SiC-monofilament-reinforced SiC or Si₃N₄ matrix composites were fabricated by hot-pressing, and their mechanical properties and effects of filaments and filament coating layers were studied. Relationships between frictional stress of filament/matrix interface and fracture toughness of SiC monofilament/Si₃N₄ matrix composites were also investigated. As a result, it was confirmed experimentally that in the case of composites fractured with filament pullout, the fracture toughness increased as the frictional stress increased. On the other hand, when frictional stress was too large (>about 80 MPa) for the filament to be pulled out, fracture toughnesses of the composites were almost the same and not so much improved over that of Si₃N₄ monolithic ceramics. The filament coating layers were found to have a significant effect on the frictional stress of the SiC monofilament/Si₃N₄ matrix interface and consequently the fracture toughness of the composites. Also the crack propagation behavior in the SiC monofilament/Si₃N₄ matrix composites was observed during flexural loading and cyclic loading tests by an in situ observation apparatus consisting of an SEM and a bending machine. The filament effect which obstructed crack propagation was clearly observed. Fatigue crack growth was not detected after 300 cyclic load applications.     

MoSi2增韧Si3N4陶瓷的研究

以Ｓｉ粉和Ｍｏ粉为原料,采用反应烧结－热压吉二步法得到了Ｓｉ３Ｎ４－ＭｏＳｉ２复合材料,并对材料进行了力学性能和Ｘ－射线衍射（ＸＲＤ）及扫描电子显微镜（ＳＥＭ）研究。认为：Ｓｉ３Ｎ４－ＭｏＳｉ２复合材料的高韧性与材料的相组成、显向下 结构、裂纹扩展方式及应力诱导开裂等有关。     

烧结助剂对氮化硅陶瓷显微结构和性能的影响

氮化硅中氮原子和硅原子的自扩散系数很低，致密化所必需的扩散速度和烧结驱动力都很小，在烧结过程中需采用烧结助剂。烧结助剂是影响氮化硅陶瓷的显微结构和性能的关键因素之一。有效的烧结助剂不但可以改善氮化硅陶瓷的显微结构，而且可以提高氮化硅陶瓷的高温性能和抗氧化性能。