B4C／Al复合材料的制备工艺和组织研究

研究了用无压浸渗法制备的B1C/Al复合材料的制备工艺和组织。通过对碳化硼陶瓷预制体成型压力和保压时间的控制,采用X射线衍射、扫描电子显微镜及能谱仪分别对B1C／Al复合材料的相组成、微观形貌和微区成分进行分析。结果表明：成型压力为100MPa,保压时间选择1．5min,预烧温度在1700℃时,可以制得组织致密、均匀的B1C／Al复合材料。金属铝在高温下浸渗时与碳化硼陶瓷骨架反应生成Al3BC,AlB2,Al2C3等陶瓷相。Al3BC和AlB2为主要反应产物。B4C／Al复合材料中碳化硼是以连续的骨架结构存在,渗入的铝相则以连续基体的形式铺满整个组织。     

高含量Sip/Al热控制复合材料性能研究

首次采用无压浸渗工艺,使Al液自发浸渗进入多孔Si预制件中,制备出Al/70vol%SiP复合材料,对该材料的浸渗过程、组织特点和热物理性能进行了分析.研究发现,与其他方法相比,无压浸渗料获得的高含量Sip/Al复合材料,在性能上具有低密度、高导热率、低膨胀系数等特点,具备了热控制材料的基本特征,明显优于Cu-W、Fe-Ni合金、Kovar合金、SiCp/al复合材料,以及采用其他工艺制备的Si/Al复合材料.     

高体积分数B4C/ZL101复合材料力学性能的研究

高体积分数颗粒增强金属基复合材料结合了陶瓷和金属的性能优势,具有轻质、高强、高模量的特点,是一种颇具应用前景的装甲材料,但此方面的报道研究较少。采用压力浸渗法制备了颗粒体积分数为50%、不同粒径的B4C/ZL101复合材料。结果表明,预制件温度为550℃、浸渗熔体温度为750℃时,采用压力浸渗可以得到颗粒分布均匀、致密度高的复合材料,组成相简单;复合材料的力学性能表明,B4C颗粒的粒径越小,复合材料的力学性能越好。当B4C颗粒粒径为3μm时,压缩强度、抗弯强度、布氏硬度分别可达1000MPa、640MPa、285HB。     

无压浸渗工艺制备铝基复合材料的研究现状和机理探讨

无压浸渗法是一类先进的金属基复合材料制备方法.总结了无压浸渗方法制备陶瓷增强金属基复合材料的工艺特点及国内外的研究现状,分析了影响无压漫渗工艺的主要因素及存在的问题,探讨了该工艺的可能机理,并指出了该工艺存在的问题和今后的研究重点.     

无压浸渗制备含镍陶瓷/铁基合金复合材料微观组织及浸渗机理

通过铁合金无压浸渗含镍氧化铝陶瓷的方法,制备了陶瓷/铁合金复合材料.其工艺过程是:将镍粉与陶瓷粉混合球磨后,压制成具有网络结构的陶瓷体,经烧结成瓷后,铁合金无压浸渗,浸渗温度1600℃,保温4h.研究结果表明,含镍陶瓷与铁合金在界面处形成锯齿状的机械啮合,两相之间无过渡层以及微裂纹存在;铁合金中的Fe、Cr元素呈梯度分...     

网状结构Si3N4陶瓷增强金属基复合材料的研究

利用有机前驱体浸渍法制备了Si3N4网络陶瓷预制体,利用液态金属浸渗法制备出Al基、Mg基复合材料.分析了在浸渗过程中浸渗温度、润湿角、浸渗时间、浸渗高度的相互关系.在压力下金属液克服浸渗阻力,使浸渗得以完成.网络陶瓷骨架孔筋表面覆盖一层氧化膜有利于自发浸渗的进行.合金中适量镁元素的存在使界面上发生轻微化学放热反应,对浸渗有利.指出压力浸渗制备铝基复合材料与无压浸渗制备镁基复合材料的特点.探讨了这种复合材料抗压强度和摩擦磨损性能特点.指出Si3N4/Al复合材料,Si3N4/Mg复合材料抗磨擦性能明显优于基体,抗拉强度大大高于基体.     

浸渗时间对无压浸渗制备Al/SiCp陶瓷基复合材料的影响

本文采用无压浸渗法,研究浸渗时间对Al/SiCp陶瓷基复合材料组织、致密度、硬度的影响。浸渗保温时间1h,能浸透,但致密度差,硬度低。保温时间3h,发生粉化现象。结果表明浸渗保温时间2h是无压浸渗较好的工艺参数。     

无压渗透法制备SiCp/Al复合材料工艺优化研究

无压渗透法是制备SiCp/Al复合材料的重要技术.应用实验方法系统地研究了无压渗透法的工艺参数和添加元素对制备工艺的影响.结果表明,在无压渗透法制备SiCp/Al复合材料的工艺过程中,浸渗温度是浸渗过程顺利进行的重要因素,900℃的浸渗温度为最佳浸渗温度.适量加入Mg元素能提高熔融金属Al和增强体SiC颗粒之间的浸润性,获得结合强度好、孔洞和疏松较少的SiCp/Al复合材料,Mg元素的最佳含量约为1.2%(质量分数).适量添加Si元素能增强熔融铝液的流动性,降低SiC颗粒与Al液间的表面张力,改善其润湿性.     

复合相变储能材料制备工艺对其浸渗率和相对密度的影响

本文探索了Na2SO4/SiO2无机盐/陶瓷基复合相变储能材料的自发熔融浸渗工艺制度.讨论了预制体制备工艺的四个主要影响因素:造孔剂含量、成型压力、烧成温度和颗粒粒度与复合相变储能材料的浸渗率和相对密度的关系,分析了熔融盐与预制体浸渗合成时,浸渗温度、浸渗时间以及浸渗方式对复合相变储能材料浸渗率和相对密度的影响.对复合相变储能材料的物相组成和显微结构进行分析,结果表明:制备工艺对复合储能材料的物相组成影响不大,Na2SO4与SiO2两相表现出较好的高温稳定性和相容性,且分布均匀.     

Ti诱导反应熔体无压浸渗法制备(W,Ti)C/Fe复合材料

研究了一种Ti诱导反应熔体无压浸渗制备复合材料的方法: 通过凝胶注模成型工艺, 以蔗糖为造孔剂制备了多孔Ti-WC陶瓷骨架预制体, 真空状态下, 在1370℃以Fe-Cr-C合金熔体无压浸渗该预制体, 经过原位反应制备了(W,Ti)C/Fe复合材料。利用SEM-EDS、 XRD对复合材料的组织结构、 元素组成及相组成进行了测试和分析。采用旋转圆盘式摩擦试验机以SiC砂浆为磨料研究了(W,Ti)C/Fe复合材料的耐磨性。结果表明: 在浸渗过程中骨架中的Ti元素的溶解析出与C元素的原位反应促进了浸渗过程的进行, 在1370℃保温1 h, 金属液即渗透整个多孔骨架, 并且在浸渗过程中仍然维持着骨架的形状, 浸渗过程中Ti-C-WC原位反应生成具有芯-壳结构的中间富Ti、 边缘富W的(W,Ti)C增强相。摩擦磨损实验结果表明, (W,Ti)C/Fe复合材料具有优异的抗磨粒磨损性能, 其耐磨性优于工业用耐磨铸铁。     

The fabrication of metal matrix composites by a pressureless infiltration technique

A novel technique for fabricating metal matrix composites by the spontaneous (pressureless) infiltration of filler preforms with molten aluminium alloys is described. Numerous reinforcing materials, including Al₂O₃ and SiC of various configurations, such as particles, agglomerates, and fibres, have been incorporated as fillers. The effects of processing variables, such as alloy chemistry, process temperature, and filler material, on the infiltration kinetics and resultant microstructures are discussed. Comparisons with existing infiltration technology and preliminary composite properties are presented.     

Aluminium-matrix silicon carbide whisker composites fabricated by pressureless infiltration

Al-matrix SiC whisker composites were fabricated by pressureless infiltration of liquid Al-Mg or Al-Si-Mg alloys at 830–950°C in the presence of N₂ into a preform of nickel coated SiC whiskers. The nickel coating on the whiskers was obtained by electroless plating and made pressureless infiltration possible. The composite made by pressureless infiltration exhibited slightly lower tensile strength and modulus and slightly higher coefficient of thermal expansion than the corresponding composite made by pressure infiltration. However, the differences were small in spite of the lack of prior evacuation in the pressureless infiltration case. On the other hand, the hardness decreased with increasing distance from the preform-melt interface much more significantly in composites made by pressureless infiltration than those made by pressure infiltration. The hardness decrease, which was attributed to a porosity increase, was larger for composites made by pressureless infiltration without prior evacuation than those made by pressureless infiltration with prior evacuation. The Al-SiC reactivity was larger for composites made by pressureless infiltration than those made by pressure infiltration, because the infiltration time was longer in pressureless infiltration.[/p]     

B4C/Al Composites Processed by Metal-assisted Pressureless Infiltration Technique and its Characterization

In order to improve the wettability between Al melt and B₄C ceramic preform during fabricating B₄C/Al composites by pressureless infiltration technique, trace amount of Ti particulates with high melting point was added into the starting materials as infiltration inducer. A simple and cost-effective method, metal-assisted pressureless infiltration technique, was developed to fabricate light-weight B₄C/Al composites. The microstructure, phases, and mechanical behavior of B₄C/Al composites were characterized by SEM, XRD, and mechanical property test. The density of the as-fabricated B₄C/Al composites was about 2.75 g/cm³ and the relative density of this kind of composites was over 97%. The as-fabricated B₄C/Al composites exhibited rather well wear resistance. The flexural and compressive strengths of the as-fabricated B₄C/Al composites were about 200 MPa and 670 MPa, respectively.     

The production of Al-Mg alloy/SiC metal matrix composites by pressureless infiltration

Metal matrix composites have been produced by pressureless infiltration of Al-Mg alloys into SiC preforms at 900°C under N₂ for different infiltration times. The wettability of the ceramic reinforcement by the Al-Mg alloy is crucial in determining whether an MMC can be produced by pressureless infiltration. Sessile drop results show that Al alloys with Mg contents greater than 8 wt% had a contact angle lower than 90°C after 5 minutes contact time. This was in agreement with the pressureless infiltration results as MMCs have been produced after 30 minutes with these alloys. Sessile drop experiments also show that SiC is similarly wetted by Al-Mg alloys under both N₂ and Ar. It is concluded that the infiltration process does not involve the intermediate nitride phase suggested by other authors.     

Mg对无压渗透制备Al/SiCp陶瓷基复合材料的影响

本文采用无压浸渗法,研究了Mg对Al/SiC.(SiC体积分数为40%-70%)陶瓷基复合材料制备及组织影响.结果表明,Al浸渗液中添加Mg可以显著提高铝液的浸润性,因为Mg扩散并富集于Al/SiCp界面,通过界面反应促使Al2O3膜的破裂降低界面张力,增加了铝合金液的流动性,而且Mg与骨架孔隙内的气氛反应形成负压,促...     

网状结构Si3N4陶瓷增强金属基复合材料的研究

利用有机前驱体浸渍法制备了Si3N4网络陶瓷预制体,利用液态金属浸渗法制备出Al基、Mg基复合材料：分析了在浸渗过程中浸渗温度、润湿角、浸渗时间、浸渗高度的相互关系。在压力下金属液克服浸渗阻力．使浸渗得以完成。网络陶瓷骨架孔筋表面覆盖一层氧化膜有利于自发娄渗的进行。合金中适量镁元素的存在使平面上发生轻微化学放热反应．对浸渗有利。指出压力浸渗制备铝基复合材料与无压浸渗制备镁基合材料的特点。探计了这种复合材料抗压强度和摩擦磨损性能特点。指出Si3N4／Al复合材料，Si3N4/Mg复合材料抗磨擦性能明显优于基休．抗拉强度大大高于基体。     

Designing of a powder compressing device with vibration and investigation of compressibility of MgO powders with this device

One of metal matrix composite (MMC) production methods is infiltration of liquid metal into preformed reinforcement. In this method, MMCs are produced by infiltration of liquid metal into preformed reinforcement using one of pressure, vacuum or pressureless (free) infiltration methods. For infiltration purposes, reinforcement materials in different figuration are preformed in desired shape and reinforcement volume ratio. In this study a vibration apparatus has been designed to compress the particulate reinforcement in a tube so that pressure or vacuum infiltration can be carried out. The compressibility of MgO powders with different sizes with this apparatus has also been investigated. It has been found that with this apparatus, it is possible to compress desired number of specimens uniformly at the same time and at the same ratio. It has also been determined that MgO powders can be compressed in different ratio due to particle sizes with this device. Compressing time of 3 min is enough to reach maximum compression ratio in MgO powders.     

无压浸渗法制备氧化态SiC颗粒增强铝基复合材料

研究了SiC颗粒在1000~1200℃的氧化行为, 其氧化增重率与保温时间符合抛物线规律, 氧化增重受扩散过程控制, 氧化激活能为219 kJ/mol. 采用预氧化处理的SiC颗粒为增强体, 含Si、Mg的铝合金为基体, 通过无压浸渗方法制备了SiC_p/Al复合材料, 分析了复合材料的微观组织与界面形貌, 探讨了无压浸渗机理. 复合材料中颗粒分布均匀, 无偏聚现象. 材料制备过程中存在界面反应, SiC颗粒表面的氧化层与铝合金中的Mg、Al反应形成了一定数量的MgAl₂O₄. 界面反应的存在提高了润湿性, 促进了无压自发浸渗.     

无压渗透法制备BN增强铝基复合材料

本文讨论了无压渗透法制备BN增强铝基复合材料的制备过程和粉体成分对于渗透的影响.采用无压渗透法制备了BN增强Al基复合材料.在800℃、N2气氛中,铝基合金可以自发的渗入Al-Mg-BN粉体.实验结果显示,渗透气氛、Mg、粉体的烧结对于无压渗透过程有重要影响.     

High strain rate characteristics of 3-3 metal-ceramic interpenetrating composites

3-3 interpenetrating composites (IPCs) are novel materials with potentially superior multifunctional properties compared with traditional metal matrix composites. The aim of the present work was to evaluate the high strain rate performance of the metal-ceramic IPCs produced using a pressureless infiltration technique through dynamic property testing, viz. the split Hopkinson's pressure bar (SHPB) technique and depth of penetration (DoP) analysis, and subsequent damage assessment. Though the IPCs contained rigid ceramic struts, the samples plastically deformed with only localised fracture in the ceramic phase following SHPB. Metal was observed to bridge the cracks formed during high strain rate testing, this latter behaviour must have contributed to the structural integrity and performance of the IPCs. Whilst the IPCs were not suitable for resisting high velocity, armour piercing rounds on their own, when bonded to a 3 mm thick, dense Al₂O₃ front face, they caused significant deflection and the depth of penetration was reduced.