层状氮化硅陶瓷的性能与结构

从结构设计的角度出发研究了层状复合Ｓｉ３Ｎ４陶瓷材料，利用轧膜使层内的晶粒，晶须产生定向增韧，通过调整外部层状复合结构得到材料的两级增韧效果，并实验制备了高韧性层状复合Ｓｉ３Ｎ４基陶瓷材料。     

热压烧结透明β-Si3N4陶瓷

采用MgSiN2作为烧结助剂,在2000℃高温下热压26h,制备了透明β-Si3N4陶瓷.X射线衍射分析表明:透明β-Si3N4陶瓷由纯β-Si3N4相组成.透明-Si3N4陶瓷的透过率随波长增加而增加,当波长为2.5 μm时透过率达到最大值,为70％,波长在0.7～4.0 μm区间,透过率保持在60％以上,截止波长为5.0 μm.     

加入纳米氮化硅对氮化硅陶瓷性能与结构影响

本文以亚微米级氮化硅为起始原料，加入纳米氮化硅来增强基体，添加氧化铝和氧化钇为烧结助剂，等静压成型，采用无压烧结的方式来制备具有优良性能的氮化硅陶瓷。主要研究了纳米氮化硅的分散；纳米氮化硅的加入量对氮化硅陶瓷力学性能的影响；纳米氮化硅的加入量对氮化硅陶瓷使用性能的影响；纳米氮化硅的加入量对氮化硅陶瓷显微结构的影响。研究结果表明：乙醇作为溶剂在分散介质为聚乙二醇的情况下，超声波震荡40分钟时，纳米氮化硅分散效果最好；随纳米氮化硅加入量的增加，显气孔率增加，吸水率增大；加入3wt％的纳米氮化硅时，试样的体积密度最大，抗弯强度、洛氏硬度、断裂韧性最好，具有较理想的显微结构。     

高速数控机床主轴用陶瓷轴承的研究

综述了国内外陶瓷滚动轴承的研究和发展现状，阐述了陶瓷球轴承的运动学、动力学的研究。     

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。     

自由扩散式高温合成氮化硅制造的热压陶瓷

创造出一种价格比较适宜的不太昂贵的工艺和材料：其性能可视为显著的成就，犹如创造出一种高性能的材料。氮化硅陶瓷制品的成本昂贵系由于原料砂的价格偏高所致。研究了以自扩散式高温合成法制造的α－Ｓｉ３Ｎ４砂在热压工艺中使用的可能性。查明，自扩散式高温合成α－Ｓｉ３Ｎ４砂在工作温度方面不如等离子化学复合材料。但是自扩散式高温合成α－Ｓｉ３Ｎ４砂在适宜的密度下具有较高的强度、抗裂性和硬度，其成本也比ＯＴＭ－９     

氮化硅对石英陶瓷性能的影响

研究了氮化硅加入物对石英陶瓷性能的影响。结果表明,氮化硅有助于石英陶瓷的烧结,而对烧结温度无影响。在1150－1200℃的温度范围内,添加0．5－1．5％的氮化硅不会引导石英玻璃的析晶。烧成在1150－1200℃温度范围内,石英陶瓷的强度、体积密度随氮化硅的添加量增大和烧结温度提高而增大,而石英陶瓷的显气孔率随氮化硅添加量的增大和烧结温度的升高而减小。     

低成本氮化硅陶瓷

对从事陶瓷行业一段时间的人来说,“低成本氮化硅陶瓷(Si_3N_4)”这个观点有些矛盾。生产氮化硅陶瓷所要求的原料和制造过程很昂贵,导致终端产品制造费用较高、价格也极高。为此,氮化硅陶瓷仅限于最高级的技术应用,其用户愿意并且有能力为氮化硅的强度和性能付出代价。     

热压氮化硅在1200℃的高温疲劳损伤

研究了热压氮化硅陶瓷的室温和高温力学性能及在１２００℃的高温疲劳损伤行为，发现材料的弹性模量、抗变强度与断裂韧性均随温度升高而下降，但在１０００℃以上降低最为显著。在１２００℃高温疲劳寿命与应力之间符合单对数线性关系经分析发现这种现象与失效的热激活过程有关。通过对实验数据，ＸＲＤ相结构、变形动力学过程和断口的微观分析证明，陶瓷高温疲劳失效机理为“杂质空穴复合作用机制”。对热压氮化硅来说，失效机理主     

废瓷掺量料对陶瓷烧成性能影响

陶瓷行业的快速发展带来了废瓷污染问题,其危害日趋严重,亟待解决.充分利用废瓷的特性,将其变废为宝,能提高产品的质量,同时也是缓解环境压力和实现节能降耗的一条重要途径,具有广阔的应用前景.     

Ceramic Properties of Europium Oxide

Europium oxide of 99.7% purity was compacted into small bars and pellets which were fired at temperatures from 1050° to 1700°C. for 2 to 120 hours in atmospheres that were oxidizing, mildly reducing (open furnace), or strongly reducing. It was found that (1) europium oxide compacts fired in oxygen for 2 hours at 1500°C. bad attained a density of 90% of theoretical and were stable in boiling water, (2) compacts fired under mildly reducing conditions at 1500°C. for 2 hours had attained a density of 84% of theoretical and disintegrated in boiling water, and (3) those fired similarly in a hydrogen atmosphere began to fuse at 1500°C. The linear thermal expansion of the compacts fired at 1500°C. in the open furnace was 10.5 x 10^-6in. perin. per°C. between 0° and 1000 °C. and their molar specific heat between 0° and 800°C. was 33.3 cal. Careful investigation of the structural changes occurring in europium oxide with rising temperature revealed that (1) the low-temperature (body-centered cubic) form inverts slowly to the high-temperature form at approximately 1050°C., (2) the high-temperature form has monoclinic symmetry, and (3) it does not revert readily to the cubic form; its theoretical density was calculated to be 8.18 gm. per cm.³.     

陶瓷轴承的特性与制造

对工程陶瓷，轴承钢等材料的重要性能进行了对比分析，对陶瓷轴承的生产工艺，检测手段，应用前景进行了介绍，论证了将工程陶瓷用于轴承制造的可行性和重要性。     

陶瓷墨水的制备及其性能研究

作为陶瓷装饰材料与计算机科学结合的交叉应用技术,陶瓷数字喷墨打印技术具有传统陶瓷装饰技术无可比拟的优势。研究利用研磨分散法成功制备出蓝色的陶瓷墨水,并探究了不同的超分散剂体系及其用量对墨水性能的影响。     

Tensile Properties of Ceramic Matrix Fiber Composites

The mechanical properties of various 2D ceramic matrix fiber composites were characterized by tension testing, using the gripping and alignment techniques development in this work. The woven fabric composites used for the test had the basic combinations of Al₂O₃ Fabric/Al₂O₃, SiC fabric/SiC, and SiC minofilament uniweave fabric/SiC. Tension testing was performed with strain gauge and acoustic emission instrumentation to identify the first-matrix cracking stress and assure a valid alignment. The peak tensile stresses of these laminate composites were about one-third of the flexural strengts. The SiC monofilament uniweave fabric (14 vol%)/SiC composites showed a relatively high peak stress of 370 MPa in tension testing.     

Preparation and Properties of Ultrafiltration Ceramic Membranes

A technology for preparing ceramic ultrafiltration membranes with a ZrO₂-based selective layer and their pore and separating characteristics are determined. The potential use of these membranes for separation or fractionation of polyvinylpyrrolidone and purification of apple pectin is demonstrated.     

Properties of a Tin Oxide-Base Ceramic Body

Some thermal and mechanical properties were measured for tin oxide-matrix compacts which nominally were composed of 99% by weight tin oxide (SnO₂) and 1% zinc oxide (ZnO). The sintered compacts were similar in strength to high–fire mullite porcelains, had superior resistance to thermal shock, and had high thermal conductivity. The tin oxide body might be expected to give good service under conditions of severe thermal shock and in an oxidizing atmosphere at temperatures up to 1500°F.     

Microstructure and Properties of Sprayed Ceramic Coating

The potential benefits of a thermal barrier coating on the heated side of diesel or turbine components are well documented, and this as well as other applications of ceramics in heat engines are being actively pursued. The ceramic coatings used in heat engines must be able to withstand severe thermal stress. The microstructure and properties of several sprayed coatings are described, including flame-sprayed alumina coatings, plasma-sprayed alumina coatings, and plasma-sprayed zirconia coatings. The results show that the modulus ( E ) of the coatings depends mainly on porosity and phase composition, and nonlinear stress-strain behavior is caused by the laminar grain structure of the coatings. The fracture strain of a coating is a major factor in the thermal shock resistance of that coating.     

陶瓷化硅橡胶的性能研究

采用甲基乙烯基硅橡胶为主体材料,在以氢氧化铝和玻璃粉为阻燃剂的基础上添加铂络合物和耐火填料(高岭土、白云母粉或硅灰石)制备陶瓷化硅橡胶,研究铂络合物和耐火填料对硅橡胶物理性能、热稳定性能和烧结性能的影响。结果表明:铂络合物与氢氧化铝有很好的阻燃协同效应,铂络合物适宜的质量分数为7.2×10~(-6);随着耐火填料用量的增大,硅橡胶的物理性能下降,耐火填料的适宜用量为20份;添加铂络合物和耐火填料的硅橡胶热稳定性能下降;烧蚀温度越高,硅橡胶的烧结产物陶瓷化效果越明显。陶瓷化硅橡胶具有优异的阻燃性能和耐火性能,添加白云母粉的陶瓷化硅橡胶的物理性能和陶瓷化效果最好。     

Mechanical Properties of Silicon Oxycarbide Ceramic Foams

The mechanical properties of ceramic foams obtained through a novel process that uses the direct foaming and pyrolysis of preceramic polymer/polyurethane solutions were investigated. The elastic modulus, flexural strength, and compressive strengths were obtained for foams in the as-pyrolyzed condition; values up to 7.1 GPa, 13 MPa, and 11 MPa, respectively, were obtained. The strength of the foam was virtually unchanged at temperatures up to 1200°C in air; however, long-term exposure at 1200°C led to a moderate degradation in strength, which was attributed to the evolution of intrastrut porosity during the oxidation of residual free carbon, as well as devitrification of the foams struts.