造孔剂含量对无压浸渗法制备SiC/Al复合材料性能的影响

采用无压浸渗法制备了SiC/Al复合材料,研究了造孔剂含量对SiC/Al复合材料性能的影响。实验结果表明:不同含量的造孔剂对残余气孔率的影响不同,随着造孔剂加入量的增加,残余气孔率先减小后增大,但试样抗弯强度呈先增加后减小。在SiC/Al复合材料中加入质量分数为20%的造孔剂时,SiC/Al复合材料的抗弯强度出现最大值,其残余气孔率达到最小值0.9%左右。     

Development of Si3Na/Al composite by pressureless melt infiltration

Pressureless infiltration process to synthesize Si3N4/Al composite was investigated. Al-2%Mg alloy was infiltrated into Si3N4 and Si3N4 containing 10% Al2O3 preforms in the atmosphere of nitrogen. It is possible to infiltrate Al-2%Mg alloy in Si3N4 and Si3N4 containing 10% Al2O3 preforms. The growth of the dense composite of useful thickness was facilitated by the presence of magnesium powder at the interface and by flowing nitrogen. During infiltration Si3N4 reacted with aluminium to form Si and AIN, the growth of composite was found to proceed in two ways, depending on the Al2O3 content in the initial preform. Firstly, preform without Al2O3 content gives rise to AIN, Al3.27Si0.47 and Al type phases after infiltration. Secondly, perform with 10% Al2O3 content gives rise to AIN-Al2O3 solid solution phase （AION）, MgAl2O4, Al and Si type phases. AlON phase was only present in composite, containing 10% Al2O3 in the Si3N4 preforms before infiltration.     

铸件表面合金化评述

简要介绍了铸件表面合金化的基本情况和应用。分析了影响合金化质量的各种因素 ,以及存在的基本问题 ,并讨论了用消失模法实现表面合金化的优点     

多孔体制备工艺对C/C-SiC复合材料弯曲性能的影响

以针刺整体炭毡为坯体,采用CVD和树脂浸渍／炭化混合法增密制备了4种C／C多孔体,然后熔硅浸渗C／C多孔体制备了C／C-SiC复合材料;研究了不同炭涂层、高温热处理对C／C-SiC复合材料弯曲强度和断裂方式的影响。结果表明：热解炭涂层可减少制备过程中炭纤维的损伤,具有适中的界面结合强度,使复合材料的弯曲强度达到161．5MPa,表现出良好的“假塑性”;适当选择高温热处理工艺可制备弯曲性能较高,具有一定“假塑性”的C／C-SiC复合材料。     

无压渗透制备金属间化合物陶瓷基复合材料的研究进展

介绍了目前国内外使用无压渗透制备金属间化合物陶瓷基复合材料几个系列：FeAl/TiC、NiAl、Ni_3Al/TiC、FeAl/WC和Ni_3Al/WC。     

Preparation and characterization of biomorphic SiC hollow fibers from wood by chemical vapor infiltration

Biomorphic SiC hollow fibers were prepared by the reactive infiltration of SiO vapor into basswood-derived charcoal. Gaseous SiO was produced from a SiO₂/Si powder mixture in Ar at elevated temperatures. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and Fourier transform-infrared spectroscopy were employed to characterize the structural morphology and phase compositions of the final products. The results show that the tubular cells in bulk charcoal are converted into lots of SiC hollow fibers with pore diameters of 10–50 μm and lengths ranging from hundreds of μm to several mm. Resulting SiC hollow fibers consist of β-SiC with a minute amount of α-SiC. The formation mechanism of SiC hollow fibers is based on the gas–solid reaction between SiO and carbon.     

金属基复合型材气压浸渗系统进口模具研究

就金属基复合型材主要是复合丝气体浸渗水平连续制备工作室模具系统进行了讨论.实践表明,合理的模具系统可以制备出合格的金属基复合型材.     

Infiltration kinetics of pressureless infiltration in SiCp／Al composites

The pressureless infiltration kinetics was investigated by plotting the infiltration distance as function of the infiltration time. The effects of key process parameters such as time, temperature, Mg content on the pressureless infiltration of silicon carbide particle compacts were studied and quantified. The preform with high volume fraction SiC was obtained by mixing SiC particles with bimodal size distribution, whose diameters are 5 and 50 btm, respectively. The results show that an incubation period exists before infiltration, the influence of temperature on the incubation time exceeds that of Mg content, infiltration rate increases with the increasing temperature and Mg content, infiltration rate decreases as Mg consumes. A model of macroscopical infiltration and microscopical infiltration of liquid alloy in porous SiC preform was proposed.     

碳纤维增强氮化物基复合材料的制备及其性能表征

合成了全氢聚硅氮烷和硼氮烷的混杂先驱体并对其结构进行了表征；以混杂先驱体和3D碳纤维编制体为原料，采用先驱体浸渍-裂解（PIP）工艺制得了碳纤维增强氮化硼．氮化硅混杂基体的复合材料，并对复合材料的力学性能和抗烧蚀性能进行了研究。结果表明，混杂先驱体中含有B—N，B—H，Si—N，Si—H，N—H等结构，无其它杂质出现；随着PIP工艺循环次数的增加，复合材料的密度随之提高：当进行4个循环时基本致密，密度达到1．50g／cm^3，弯曲强度达到156．4MPa；轨道模拟实验显示复合材料具有优异的抗烧蚀性能。