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In this study, co-deposition of zinc (Zn)-submicron sized alumina (Al2O3) particles via electrodeposition method was investigated. Composite coatings were produced using different coating parameters such as current density, pH, temperature, agitation type, and ceramic powder content of the bath solution. Structural and microstructural properties of the coatings were characterized by X-ray diffractometer (XRD) and scanning electron microscopy with electron dispersive spectroscopy (SEM–EDS). Mechanical properties of the coatings were evaluated by dynamic ultra-micro hardness (DUH) tester, a micro-indentation technique, in detail. It was found that, co-deposition of submicron sized Al2O3 particles and Zn metal was successfully achieved via electrodeposition method without any chemical interaction between the ceramic particles and the electrolyte. Comparison of SEM images belonging to the coatings fabricated to those of the reference coatings revealed that homogenous grain structure was obtained. Finally, a boost in the micromechanical properties of the coatings was gained by changing the effective co-deposition parameters such as current density and particle content in the electrolyte. 相似文献
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通过填加造孔剂方法制备了碳纳米管(CNTs)增强铝基复合泡沫,采用热机械分析仪研究了测试温度、频率、外加振幅、泡沫的孔隙率和CNTs含量对其阻尼性能的影响,并分析了相关阻尼机制。结果表明:复合泡沫铝的阻尼性能随孔隙率和振幅的增大而提高,随着频率的增加而下降。在环境测试温度25~200℃范围内,复合泡沫的损耗因子变化较小;当温度高于200℃后,损耗因子随温度升高有明显的提高。CNTs的加入可以显著提高泡沫铝的阻尼性能,常温下3.0% CNTs增强的铝基复合泡沫的损耗因子达0.27,为泡沫铝的3.71倍。复合泡沫的阻尼机制主要为位错阻尼、晶界阻尼、孔隙阻尼、CNTs的本征阻尼和CNTs-Al间界面阻尼,其中本征和界面阻尼发挥了重要的增强作用。 相似文献
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The large quantities of the petroleum-based foam materials used have raised concern due to their negative effects on the environment, predominantly single-use articles in packaging applications. Thus, considerable efforts have been put forth to develop environmentally friendly alternatives and, in particular, starch foams. Many techniques including extrusion, hot-mold baking/compression, microwave heating, freeze-drying/solvent exchange, and supercritical fluid extrusion can be used to produce starch foams with different cellular structures and properties. Starch by itself is, however, rather weak and water sensitive. To improve microstructure, mechanical and thermal properties, moldability, water resistance, lightness and other properties of starch-based foams, many approaches, e.g., chemical modification of starches, blending with various biodegradable polymers, incorporation of natural fibers, and addition of nanofillers, have been attempted and are intensively reviewed in this article. 相似文献
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《Materials Science & Technology》2013,29(5):923-927
AbstractThe aluminium composite foams reinforced by different volume fractions of SiC particles were manufactured with the direct foaming route of melt using different contents of CaCO3 foaming agent. The density of produced foams changed from 0·43 to 0·76 g cm?3. The microstructural features and compressive properties of the Al/SiCp composite foams were investigated. Compressive stress–strain curve of Al/SiCp composite foams is not smooth and exhibits some serrations. At the same relative density of composite foams, the plateau stress of the composite foams increases with increasing volume fraction of SiCp and decreasing weight percentage of CaCO3. The relation between plateau stress, relative density, weight percentage of CaCO3 and SiCp volume fraction of Al/SiCp composite foams with a given particle size was investigated. 相似文献
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《Materials Letters》2007,61(8-9):1771-1774
Closed-cell Al–Mg alloy (A5052) foams are produced through accumulative roll-bonding (ARB) process. The preform plate containing uniform titanium hydride (TiH2) particles is manufactured after six ARB cycles. Macroscopic porosity is as large as 47% in the condition of infrared heating at 913 K. Compressive tests are carried out in the condition of different loading axes. Yield stress in the normal direction (ND) was lower than other loading directions. Anisotropic deformation behavior is due to the anisotropic cell morphology which was induced during the ARB process. 相似文献
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Satendra Kumar T.S.N. Sankara Narayanan S. Ganesh Sundara Raman S.K. Seshadri 《Materials Chemistry and Physics》2010,119(1-2):337-346
Thermal oxidation (TO) of Ti6Al4V alloy was performed at 500, 650 and 800 °C for 8, 16, 24 and 48 h in air. The morphological features, structural characteristics, microhardness and corrosion resistance in Ringer's solution of TO Ti6Al4V alloy were evaluated and compared with those of the untreated one. The surface morphological features reveal that the oxide film formed on Ti6Al4V alloy is adherent to the substrate at 500 and 650 °C irrespective of the oxidation time whereas it spalls off when the alloy is oxidized at 800 °C for more than 8 h. X-ray diffraction (XRD) measurement reveals the presence of Ti(O) and α-Ti phases on alloy oxidized at 500 and 650 °C, with Ti(O) as the dominant phase at 650 °C whereas the alloy oxidized at 800 °C exhibits only the rutile phase. Almost a threefold increase in hardness is observed for the alloy oxidized at 650 °C for 48 h when compared to that of the untreated one. Thermally oxidized Ti6Al4V alloy offers excellent corrosion resistance in Ringer's solution when compared to that of the untreated alloy. 相似文献
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Metal foams are used as absorbers for kinetic energy but predominantly, they have only been investigated under quasi-static load-conditions. Coating of open-cell metal foams improves the mechanical properties by forming of Ni/Al hybrid foam composites. The properties are governed by the microstructure, the strut material and geometry. In this study, the strain-rate effects in open-cell aluminium foams and new Ni/Al composite foams are investigated by quasi-static compression tests and low-velocity impact. For the first time, drop weight tests are reported on open-cell metal foams, especially Ni/Al composite foams. Furthermore, size-effects were evaluated. The microstructural deformation mechanism was analysed using a high-speed camera and digital image correlation. Whereas pure aluminium foams are only strain-rate sensitive in the plastic collapse stress, Ni/Al foams show a general strain-rate sensitivity based on microinertia effects and the rate-sensitive nano-nickel coating. Ni/Al foams are superior to aluminium foams and to artificial aluminium foams with equal density. 相似文献
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采用熔体发泡法,以原位自生Mg2Si/Al复合材料为基体,CaCO3作发泡剂,通过控制温度和搅拌参数,成功制备出不同密度的闭孔泡沫铝。通过静态压缩性能试验发现:泡沫Mg2Si/Al复合材料的压缩过程具备泡沫金属压缩变形的三阶段(弹性变形、应力平台区、致密化阶段)特征;压缩屈服强度和平台应力均随密度增加而增大;屈服点附近应力值下降,应力平台区出现锯齿波形,暴露出孔壁的脆性破裂特征。经过人工时效热处理,泡沫Mg2Si/Al复合材料的屈服强度显著增大。通过观察孔壁的微观组织发现,Al基体被孔壁中粗大的Al+Mg2Si伪共晶组织所割裂。 相似文献
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To enhance the wear resistance and friction-reducing capability of titanium alloy, a process of laser cladding γ-NiCrAlTi/TiC + TiWC2/CrS + Ti2CS coatings on Ti–6Al–4V alloy substrate with preplaced NiCr/Cr3C2–WS2 mixed powders was studied. A novel coating without cracks and few pores was obtained in a proper laser processing. The composition and microstructure of the fabricated coating were examined by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) techniques, and tribological properties were evaluated using a ball-on-disc tribometer under dry sliding wear test conditions at 20 °C (room-temperature), 300 °C, 600 °C, respectively. The results show that the coating has unique microstructure consisting of α-Ti, TiC, TiWC2, γ-NiCrAlTi, Ti2CS and CrS phases. Average microhardness of the composite coating is 1005 HV0.2, which is about 3-factor higher than that of Ti–6Al–4V substrate (360 HV0.2). The friction coefficient and wear rate of the coating are greatly decreased due to the combined effects of the dominating anti-wear capabilities of reinforced TiC and TiWC2 carbides and the CrS and Ti2CS sulfides which have excellent self-lubricating property. 相似文献
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In an effort to explore alternate means of mechanical characterization of small material volumes, a nanocrystalline Al–Mg alloy synthesized via cryomilling and consolidated by cold isostatic pressing with subsequent extrusion was subjected to nanoindentation testing. The data collected from these tests was subjected to two different data analysis techniques (one proposed by Dao et al. (2001) and one proposed by Ogasawara et al. (2006)) in an effort to investigate the capabilities of such techniques in full, accurate elastoplastic characterization. A commercially available, coarse-grained sample of this same Al–Mg alloy was also tested to investigate these models’ capabilities of distinguishing between the two types of material. Nanoindentation, as expected, proved to accurately predict the elastic modulus of a tested material. Also, these methods provided evidence that through determination of strain-hardening exponent and yield stress, they could reasonably estimate the plastic properties of a tested material. Both models seemed to slightly overestimate the strength of the nanocrystalline material (according to previously reported values for similar material). In terms of the coarse-grained material, Ogasawara’s model appeared to overestimate the strength while Dao’s model provided estimations closer to values reported in literature. Finite element analysis was used as a verification mechanism for the property values extracted from the nanocrystalline material, and initial results show signs of good accuracy of characterization. 相似文献
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The ageing response of 2124 Al-SiC particulate metal-matrix composite (MMC) and unreinforced alloy has been examined using hardness measurements and Arrhenius analysis. The formation of phases during precipitation has been studied using differential scanning calorimetry (DSC). The MMC exhibits accelerated ageing compared to unreinforced alloy, due to enhanced S formation. The activation energy for diffusion is lower in the MMC than in the unreinforced alloy. DSC scans show Guinier-Preston B (GPB) zone nucleation to occur at a lower temperature in the MMC, whilst the total volume of GPB zones formed is smaller than in the unreinforced alloy. A model has been proposed to explain the GPB zone formation behaviour, in which ease of GPB zone nucleation varies within the MMC, as a function of ageing time and of position within the matrix. S formation is enhanced in the MMC because of improved diffusion and a large increase in density of heterogeneous nucleation sites compared to the unreinforced alloy. 相似文献
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Dynamic compressive behavior of aluminum alloy foams 总被引:3,自引:0,他引:3
Feng Yi Zhengang Zhu Shisheng Hu Pan Yi Linghui He Tao Ning 《Journal of Materials Science Letters》2001,20(18):1667-1668
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聚甲基丙烯酰亚胺(PMI)泡沫制备及结构表征 总被引:4,自引:0,他引:4
以甲基丙烯酸、甲基丙烯腈和甲基丙烯酰胺为主要单体原料,在适当的发泡剂存在下,以过氧化物为引发剂引发单体共聚,制得甲基丙烯酸-甲基丙烯腈-甲基丙烯酰胺共聚物,并在高温下进行发泡和环化反应,制得聚甲基丙烯酰亚胺(PMI)泡沫,并表征了PMI泡沫的结构. 相似文献
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Fei-Yi Hung Truan-Sheng Lui Li-Hui Chen Han-Wen Chang Zong-Fu Chen 《Journal of Materials Science》2007,42(13):5020-5028
Both Al–Zn alloy and Mg–Al–Zn alloy are considered as high damping and light materials. This study investigated the effects
of the structure and the composition on the vibration fracture characteristics of the Al–xZn alloy and the Mg–xAl–Zn alloy under resonance. For Al–xZn (x = 7, 11, 49, and 83 wt.%) alloys, under both constant force and initial-deflection conditions, the 7Zn specimen showed the
greatest vibration life. For Mg–xAl–Zn (x = 3, 6, and 9 wt.%) alloys, experimental results indicate that the AZ31-F as-extruded samples showed a greater vibration
life, while high Al fully annealed samples (AZ91-O) had greater vibration fracture resistance under constant force conditions. 相似文献
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A centrifugal casting method is presented in this paper for processing Al/SiCp Functionally Gradient Material (FGM), along with the corresponding microstructural characterization. Results are presented and discussed on SiC particles distribution, particles-solidification front interactions, matrix micro-structure, and porosity distribution in the castings as a function of the centrifugal forces applied. Three different casting rotational speeds (700, 1000 and 1300 rpm) were utilized while keeping all other casting conditions constant. For the highest speed applied, a variation of graded composition in the range of 20 to 44 vol% of SiC was obtained. Moreover, such progressive concentration of particles was observed to be very homogeneous due to engulfment of particles (promoted by the high relative velocity between the solidification front and particles) and also as a consequence of elevated cooling rates developed in this case. Additional results showed that the matrix micro-structure is modified according to the SiC reinforcement content and cooling rates, which both depend on the centrifugal forces applied. 相似文献