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原位合成铝基复合材料中颗粒沉降的研究 总被引:12,自引:3,他引:12
对混合盐法制备原位TiB2 颗粒增强铝基复合材料进行了研究。试验发现当TiB2 颗粒含量较高 [w(TiB2 ) >8% ]时 ,出现组织恶化的现象。从颗粒团聚、偏聚及沉降的角度 ,系统地分析了产生此种现象的原因。通过界面活性元素Mg的适量加入 ,改善TiB2 颗粒与Al液界面的润湿情况 ,阻止了颗粒的团聚 ;通过改善工艺参数 ,利用快速搅拌技术 ,有效地抑制了颗粒的偏聚与沉降 相似文献
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采用碳纳米管改善纤维与基体间的界面结合,同时利用碳纳米管自身的优异性能对碳化硅纤维增强碳化硅复合材料(SiCf/SiC)进行二次增强。通过化学气相沉积工艺(CVD)在SiC纤维编织件内原位生长碳纳米管,优化碳纳米管原位生长过程中的碳源流量、反应温度和反应时间等工艺参数,对碳纳米管的原位生长工艺及机理进行系统分析,并结合先驱体浸渍裂解工艺(PIP)制备CNTs-SiCf/SiC复合材料,探讨原位生长碳纳米管的引入对复合材料力学性能的影响。结果表明,优化后的工艺参数如下:反应温度750℃,C2H2、H2和N2流量比1/1/3,C2H2流量100~150 mL/min,反应时间60 min;碳纳米管的引入使SiCf/SiC复合材料的弯曲强度、弯曲模量和断裂韧性分别提高了16.3%、90.4%和106.3%。 相似文献
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选用Al-Zr(CO3)2反应组元,通过熔体直接反应法原位合成了(Al3 Zr Al2O3)p/Al颗粒增强铝基复合材料,增强颗粒粒度为0.5~3.0μm.采用旋转柱体法测试了合成过程中复合材料熔体的表观粘度.结果表明,颗粒体积分数为5%时,熔体表观牯度-时间曲线呈抛物线形状,25 min后粘度稳定在0.75 Pa·s,较纯铝的0.24 Pa·s增加了两倍多,原因是悬浮于铝液中的增强颗粒属于微米级,凝固组织中颗粒分布弥散均匀;颗粒体积分数为15%时,熔体表观粘度随时间增加逐渐上升,凝固组织中出现颗粒团聚现象.因此在原位合成复合材料工艺中,要综合考虑反应物加入量与收得率之间的关系,以及熔体表观粘度与凝固组织的关系. 相似文献
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原位合成铝基复合材料凝固组织中TiB2粒子的特征 总被引:8,自引:2,他引:8
杨平 《中国有色金属学报》1999,9(4):752-758
分析了原位合成制备的TiB2 粒子强化铝基复合材料不同凝固组织中TiB2 粒子的分布规律和形貌特征。研究结果表明, TiB2 在该复合材料中细化晶粒的作用较弱, 但有明显的聚集倾向, 其聚集程度与熔炼方式和加热温度有关; 经半固液成型处理的组织中TiB2 的分布特征未改善; 六边形和长条形TiB2 可以是同一形态的粒子在空间不同方位的表现, 六边形TiB2 的侧面为{1210} 面; 测定了TiB2粒子的尺寸分布。 相似文献
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多元氧化物和铝原位反应制备铝基复合材料的组织和性能 总被引:2,自引:0,他引:2
采用SEM、EDS、XRD、TEM和拉伸强度测试等研究Al2O3粒子增强的ZL109铝基复合材料。结果表明:多元氧化物和铝原位反应生成的Al2O3粒子尺寸细小,粒径约为0.1μm,在基体中弥散分布,与基体存在共格关系,(001)α(Al)//(010)α-Al2O3,[110]α(Al)//[001]α-Al2O3。原位反应中生成的金属间化合物经T6处理后,以Al5FeSi、FeCr、Mg2Si、Al3Ni、Al2Cu和Al7Cu4Ni相的形式存在于基体中,使得复合材料在300℃的拉伸强度达到163.4 MPa,较基体的提高7.9%。随Al2O3粒子含量的增加,25℃时,复合材料断口断裂方式由韧性断裂转变为解理断裂,再到穿晶断裂;而300℃时,断口断裂转变方式为脆性断裂到延性断裂。 相似文献
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利用激光熔铸技术制备多壁纳米碳管增强铝基复合材料,并使用SEM、XRD对其熔铸成形性以及纳米碳管与基体金属界面结合行为进行观察和分析.结果表明,在单位面积激光能量为800×105J/m2时,纳米碳管增强铝基复合材料能够熔合而不破坏纳米碳管结构;在该复合材料中适量添加表面张力较低的金属Mg,可降低基体铝的表面张力,进而降低铝-纳米碳管的液固界面能,改善铝合金和纳米碳管的润湿性;当纳米碳管含量为5%(质量分数)时,并添加3%(质量分数)合金化元素Mg,激光熔铸的复合材料熔合性较好,铸块致密,在复合铸块的断口上能观察到增强体纳米碳管. 相似文献
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Dong Shurong 《中国有色金属学会会刊》1999,9(3)
1 INTRODUCTIONBecauseoftheirstrength,highelasticmodulus,largeratioofslenderness(100~1000)andwearresistance,thediscoveryofthecarbonnanotubeshasdrawngreatattentions[1~3].Theyshowgreatpotentialasfiberreinforcements.TsinghuaUniversityhassuccessfullyap… 相似文献
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Structure formation during processing short carbon fiber- reinforced aluminum alloy matrix composites 总被引:1,自引:0,他引:1
S. Ciby B. C. Pai K. G. Satyanarayana V. K. Vaidyan P. K. Rohatgi 《Journal of Materials Engineering and Performance》1993,2(3):353-357
Nickel- and copper-coated, as well as uncoated, short carbon fibers were dispersed in melts of aluminum or aluminum alloys
by stirring followed by solidification of composite melts. Microstructural examina-tion of cast composites indicated extensive
damage to the surface of the carbon fibers when uncoated carbon fibers were introduced into the melt under the conditions
of the present investigation. When nickel- or copper-coated carbon fibers were used to make composites under similar conditions,
the fibers generally did not exhibit observable amounts of fiber surface degradation at the interface, except for small islands
of an Al4C3 phase. When nickel-coated carbon fibers were used to make composites, the coating reacted with the melt, and NiAl3 intermetallic phase particles were observed in the matrix away from the fibers, indicating a preference for nucleation of
NiAl3 away from the fiber surfaces. Under a transmission electron microscope (TEM), the NiAl3 phase was not observed on the surface of carbon fi-bers, except in some regions where the NiAl3 phase engulfed the carbon fibers during growth. When cop-per-coated carbon fibers were used to make composites, the coating
reacted with the melt, and particles of CuAl2 intermetallic compound were generally dispersed in the matrix away from the fibers, except for a few locations where the
CuAl2 phase was found at the interface under TEM observation. These micro-structures are discussed in terms of nucleation of primary
α aluminum and NiAl3 or CuAl2 phases and the interaction between short carbon fibers and these phases during growth while the composite was so-lidifying.
Additionally, the role of the reaction between nickel or copper coatings and the melt on struc-ture formation is discussed;
some of the differences between the nickel and copper coatings are attributed to the fact that nickel dissolves with an exothermic
reaction. The differences between solidification of short fiber composites and particle or fiber composite are also discussed. 相似文献
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Multiwalled carbon nanotubes(CNTs) were coated by a molybdenum layer using carbonyl thermal decomposition process with a precursor of molybdenum hexacarbonyl.The Mo-coated CNTs(Mo-CNTs) were added into copper powders to fabricate Mo-CNT/Cu composites by means of mechanical milling followed by spark plasma sintering.The Mo-CNTs were uniform dispersion in the Cu matrix when their contents were 2.5 vol.%-7.5 vol.%,while some Mo-CNT clusters were clearly observed at additions of 10.0 vol.%-15.0 vol.% Mo-CNTs in the mixture.The mechanical,electrical,and thermal properties of the Mo-CNT/Cu composites were characterized,and the results showed that the tensile strength and hardness were 2.0 and 2.2 times higher than those of CNT-free specimens,respectively.Moreover,the Mo-CNT/Cu composites exhibited an enhanced thermal conductivity but inferior electrical conductivity compared with sintered pure Cu.The uncoated CNT/Cu composites were fabricated by the similar processes,and the measured tensile strength,hardness,thermal conductivity,and electrical conductivity of the CNT/Cu composites were lower than those of the Mo-CNT/Cu composites. 相似文献
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E. Titus N. Ali G. Cabral J. Gracio P. Ramesh Babu M. J. Jackson 《Journal of Materials Engineering and Performance》2006,15(2):182-186
This article reports key findings on the chemical functionalization of carbon nanotubes (CNT). The functionalization of chemical
vapor-deposited CNT was carried out by treating tubes with polyvinyl alcohol through ultrasonication in water with the aid
of a surfactant. The surfactant is expected to promote the unbundling of aggregated CNT. The characterization of functionalized
samples using thermogravimetric analysis, Fourier transform infrared spectroscopy, and Raman spectroscopy revealed that the
CNT were functionalized by the interaction of carboxylic acid and hydroxyl groups. From the characterization studies, it is
apparent that there is a strong interaction between these functional groups and the covalently bonded carbon in the CNT network.
The functionalization process enabled good CNT dispersion in the solution, and the CNT remained in suspension for many days.
To support the effective functionalization of the tubes, the interaction of functionalized CNT with Ni ions is also demonstrated.
This paper was presented at the fourth International Surface Engineering Congress and Exposition held August 1–3, 2005 in
St. Paul, MN. 相似文献
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Short carbon fiber felts with an initial porosity of 89.5% were deposited by isobaric, isothermal chemical vapor infiltration using natural gas as carbon source. The bulk density of the deposited carbon/carbon (C/C) composites was 1.89 g/cm3 after depositing for 150 h. The microstructure and mechanical properties of the C/C composites were studied by polarized light microscopy, X-ray diffraction, scanning electron microscopy and three-point bending test. The results reveal that high textured pyrolytic carbon is deposited as the matrix of the composites, whose crystalline thickness and graphitization degree highly increase after heat treatment. A distinct decrease of the flexural strength and modulus accompanied by the increase of the toughness of the C/C composites is found to be correlated with the structural changes in the composites during the heat treatment process. 相似文献