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1.
Utilizing the existing properties of steel, a modern technological society has been constructed. While there are over 25,000
worldwide equivalent steels based on manipulating the eutectoid transformation, there exist only a handful of commercial nanostructured
steel alloys based on manipulating the more complex glass devitrification transformation. Thus, research on nanostructured
steels is in its infancy, and many further developments are expected with the demonstrated promise of developing new combinations
of superior properties. In this article, seven enabling metallurgical factors are presented that ultimately allow a variety
of nanostructured steel products to be produced in an ever-increasing array of industrial processing techniques. Additionally,
a case example of the formation of nanostructured steel are given showing how these factors can be harnessed on an industrial
scale. 相似文献
2.
Due to increasing use of clay/epoxy nanocomposites in industry, investigation of mechanical properties of clay nanocomposites has become of great interest. While the stiffening mechanism of clay nanocomposites is well documented, there is still not a clear understanding about how addition of clays affect the fracture behavior of clay/epoxy nanocomposites. The main aim of this paper is to measure and explain the effect of clays on ductility reduction of these nanocomposites. First, epoxy and clay/epoxy nanocomposites with different clay weight ratio were built. Then, the damage parameters of epoxy and clay/epoxy nanocomposites were measured by variation of the elasticity modulus. Based on loading–unloading experiments, the Lemaitre damage parameters for epoxy and clay/epoxy nanocomposites were extracted. Crack initiation and propagation in dog-bone sample were simulated for epoxy and clay/epoxy nanocomposites using the eXtended Finite Element Method (XFEM). The comparison between experimental and numerical results shows that the proposed method can predict the crack initiation location and propagation path in clay/epoxy nanocomposites. 相似文献
3.
通过溶胶凝胶法和氢气还原法制备出Co纳米颗粒并以此作为催化剂材料,通过催化裂解苯的方法,实现了较低温度(460℃)下在Co纳米颗粒表面上合成碳纳米管。采用X射线衍射、激光喇曼光谱、场发射扫描电镜、透射电子显微镜和振动样品磁强计对所合成的碳纳米材料进行了表征。通过优化实验参数,可制备出最大产率和纯度分别为约50和98.02%(质量分数)的碳纳米管。由于铁磁性Co纳米颗粒的进入,使得整个复合物表现出比较好的磁性能。和以往以苯作为碳源合成碳纳米材料相比,此合成方案简单、成本低,且对环境无任何危害,非常适用于磁性碳纳米复合物的批量合成。 相似文献
4.
V. Sivasubramaniam N.S. Bosco J. Janczak-Rusch J. Cugnoni J. Botsis 《Journal of Electronic Materials》2008,37(10):1598-1604
The effects of particle reinforcement of Sn-4.0wt.%Ag-0.5wt.%Cu (SAC405) lead-free solder on interfacial intermetallic layer
growth and strength of the ensuing joints through short-term isothermal aging (150°C) were studied. Composite solders were
prepared by either incorporating 2 wt.% Cu (3 μm to 20 μm) or Cu2O (∼150 nm) particles into SAC405 paste. Aggressive flux had the effect of reducing the Cu2O nanoparticles into metallic Cu which subsequently reacted with the solder alloy to form the Cu6Sn5 intermetallic. While all solders had similar interfacial intermetallic growth upon reflow, both of the composite solders’
growth rates slowed through aging to reach a common growth rate exponent of approximately 0.38, considerably lower than that
of the nonreinforced solder (n = 0.58). The nanoscale reinforced solder additionally exhibited the highest tensile strength in both the initial and aged
conditions, behavior also attributed to its quick conversion to a stable microstructure. 相似文献
5.
Bo Lei Xiaofeng Chen Yingjun Wang Naru Zhao Guohou Miao Zhengmao Li Cai Lin 《Materials Letters》2010,64(21):2293-12734
In this study, we reported a facile method to prepare porous bioactive glass microparticles. Porous particles were synthesized by sintering hollow bioactive glass microspheres obtained using a sol-gel co-template technology. The results showed that porous bioactive glass particles possessed a narrow particle size distribution, a relatively porous surface morphology and a hollow structure. It is worth to say that the resulting microparticles present an amorphous structure although the sintering temperature was improved compared to hollow microspheres. The presence of macropore on the shell may provide an efficient method to carry drugs in the hollow cores. Considering the high deposit rate of nanoscale apatite for bioactive glass materials, the porous microparticles should have potential applications in drug and bioactive molecules delivery, in addition to bone tissue regeneration. 相似文献
6.
7.
Aim: The purpose of this study is to develop an appropriate dispersion system containing flunarizine, and most of all, to improve the chemical stability of flunarizine. Method: In this study, a higher incubation temperature (60°C), to induce a faster chemical degradation, was adopted to optimize a better vehicle, an appropriate pH value, and an effective antioxidant system for flunarizine. Results: The chemical stability of flunarizine was improved significantly in lipid microspheres (LMs) compared with the aqueous solution. The optimal formulation of LMs for flunarizine at pH 8.0 is composed of (w/v): flunarizine 0.1%, dl-α-tocopherol 0.1%, medium-chain triglyceride 5%, long-chain triglyceride 5%, soybean lecithin 1.8%, poloxamer 188 0.4 %, Tween-80 0.2%, glycerol 2.5% and l-cysteine 0.05%, Na2SO3 0.15%, and EDTA 0.01%. Conclusions: The long-term stability investigation, stored at 10 ± 2°C and 25 ± 2°C for 6 months, witnessed the better chemical stability of flunarizine in LMs. An intravenous delivery system of LMs for flunarizine focusing on a better chemical stability of flunarizine has been successfully developed and optimized. 相似文献
8.
Mehdi Abdollahi Masoud Rezaei Gholamali Farzi 《International Journal of Food Science & Technology》2014,49(3):811-818
A combination of chitosan biopolymer, nanoclay and rosemary essential oil was prepared as a functional bionanocomposite (FBN). Its ability to improve the shelf life of refrigerated (4 ± 1 °C) silver carp fillets was studied. The fresh fillets were left untreated as a control or coated with chitosan, chitosan/clay bionanocomposite and chitosan/clay/rosemary essential oil (Ch/clay/REO) FBN. Then, they were evaluated for chemical, microbial and sensory properties over 16‐day storage. The samples coated with the FBN had the lowest pH and total volatile basic nitrogen. Ch/clay/REO coating efficiently retarded lipid oxidation by decreasing peroxide, free fatty acid and thiobarbituric acid production in the samples. The coating also reduced total viable and psychrotrophic count of the fillets more than 1.5 log by the end of storage. 相似文献
9.
Biodegradable amino acid modified nanocaly was applied to produce nylon-6/nanoclay composite fibers using melt blending and melt spinning processes. Field emission scanning electron microscopy images showed that the surface of composite fibers was uniform and free from defects. Layer spacing of modified nanoclay was increased due to the penetration of polymer molecules into clay layers. Crystallinity, γ crystalline percentage and total molecular orientation of composite fibers were higher in comparison to neat nylon-6 fibers, as revealed by WAXD and birefringence measurements. Tensile strength of composite fibers was lower when compared to neat nylon-6 fibers. This may be attributed to some aggregation of nanoclay and its weakening effect. Melting and glass transition temperature of composite fiber was decreased due to the addition of modified nanoclay, indicating the formation of γ crystals and also breaking of some hydrogen bonds between the polymer molecules and the formation of new hydrogen bonds between the modified clay and the polymer molecules. 相似文献
10.