Papers by Keyword: Nanostructured

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Authors: Zhi Fang Cheng, Hong Sheng Ding, Hui Rong, Li Geng Zhao
Abstract: Nano-structured and micron Al2O3-13%TiO2 coatings were deposited by air plasma spraying.Wear properties of the coatings under different temperature trough SRV friction and wear testing machine were studied, the results shows that the friction coefficient of nano and micron Al2O3-13%TiO2 coatings both have rising trend.with the temperature increases.The wear volume of micron coating is 1.8-2 times that of the nano coating..The nanometer Al2O3-13%TiO2 coating slide with ZrO2 is still compact and has no large crack after abrasion.
Authors: Kenong Xia, Wei Xu, Xiao Lin Wu, S. Goussous
Abstract: Severe plastic deformation (SPD) has received considerable attention for its capability to produce ultrafine and nano structured materials. On the one hand, SPD, especially in the forms of equal channel angular pressing (ECAP) and high pressure torsion (HPT) is able to refine bulk materials with coarse grain structures. On the other hand, SPD has been used to synthesise bulk materials from particles. It enables particles from nano to micro scales to be consolidated into fully dense materials at much lower temperatures and shorter times, compared to the conventional sintering processing. It is particularly relevant to consolidating particles with non-equilibrium microstructures and to producing complex multiphase alloys. In this summary, ECAP as an effective process to synthesise a range of light metal based materials from particles with various sizes and structures, including aluminium and aluminium composites, titanium and magnesium, will be demonstrated. Full density and good bonding are achieved easily with the application of a back pressure. Microstructures from nano to ultrafine scales have been produced, resulting in significantly enhanced strength. Simultaneous increase in ductility has also been achieved in some alloys by virtue of multi-scale structures.
Authors: Kenong Xia
Abstract: The progress in bulk ultrafine and nanostructured materials through consolidation of particles by severe plastic deformation (SPD) is reviewed. The focus is on the processes of high pressure torsion (HPT) and equal channel angular pressing (ECAP) with or without the application of a back pressure. Various materials consolidated are described in terms of their densities, microstructures and mechanical properties. The important processing parameters and their effects on the resulting materials are discussed. It is shown that SPD consolidation of particles is an effective way of producing bulk nanostructured materials although much work is needed to understand the consolidation behaviour and to design the optimum compositions and microstructures.
Authors: Nur Arifah Ismail, Mohd Hasmizam Razali, Khairul Anuar, Mat Amin
Abstract: In this research, the effect of different hydrothermal treatment temperature (100, 150, and 200 °C) on the products obtained by hydrothermal method was studied. Various characterization techniques was carried out such as X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive of x-ray spectroscopy (EDX) and fourier transform infrared spectroscopy (FTIR). XRD analysis shows that titanate phase was formed at 150 and 200 °C hydrothermal treatment. On the other hand, at 100 °C anatase TiO2 phase structured was gained which is similar with the TiO2 precursor. Morphological study using FESEM revealed that nanofibers and nanorods samples obtained at 150 °C and 200 °C, respectively. At 100°C, irregular shaped particle was attained similar with TiO2 precursors. FTIR spectra for the all studied sample displayed three main broad peaks at the range of 3700-2800, and 1800-1400 assigned to –OH stretching and deformation mode due to H2O molecules and M-O stretching mode at 900-400 cm-1 assigned to Ti-O bond.
Authors: Z.B. Wang, N.R. Tao, W.P. Tong, Jian Lu, K. Lu
Abstract: By means of surface mechanical attrition treatment (SMAT), nanostructured (NS) surface layers were fabricated on a pure iron plate and a low carbon steel plate. Cr diffusion behaviors in the NS Fe phase and the SMAT low carbon steel were investigated. Experimental results showed the activation energy of Cr diffusion in the NS Fe is comparable to that of the GB diffusion, but the pre-exponential factor is much higher. A much thicker Cr-diffusion surface layer was obtained in the SMAT low carbon steel plate than in the coarse-grained one after the same chromizing treatment. The much enhanced diffusivities of Cr in the SMAT samples can be attributed to numerous GBs and triple junctions with a high excess stored energy in the NS surface layer.
Authors: Yusoff M.S. Meor, Muslimin Masliana, Paulus Wilfred
Abstract: Black aluminium dross produced from a local aluminium smelting plant was used in this study. Solvothermal method was used to produce nanostructured alumina from this waste. Initial product obtained is of low quality with 86.9% Al2O3 content and mixed crystalline phases of 71% α-alumina and 29% calcium dodeca aluminate (CaO(Al2O3)6). The introduction of the fractional precipitation stage into the process helps in improving the purity of the alumina product to 96.5% and also produces 100% α-alumina crystalline phase. The study also shows that the crystallite size of the α-alumina products produced from this process is less than 100nm.
Authors: Xin Fang Zhang, Xiao Qing Guo, Chang Yin Gao, Zhi Qiang Jiang
Abstract: The effects of 2at.% Ga addition on the microstructure and mechanical properties of the TiCu-base nano/ultrafine bimodal structured alloy were investigated systematically through XRD, OM, compressive test and SEM. The results showed that constitutional phases were changed from bcc -Ti(M) to unknown nanostructure + bcc -Ti(M), content of nanostructured matrix is increased, the calculated mean crystalline size was decreased from 12.6 to 11.7nm, and also, the yield and maximum strengths and plasticity were enhanced markedly. The reasons, which caused these phenomenons, were discussed.
Authors: A. Norhidayah, A. Noriham, Mohamad Rusop
Abstract: In this study, the effect of nanonization on antioxidant activity of Zingiber officinale (ginger) Ross rhizome prepared using a wet milling process were investigated. The antioxidant activity was estimated based on the Total Phenolic Content (TPC) and Total Flavonoid Content (TFC) and measured using FRAP, ABTS and DPPH assays. Particle size of the initial ginger rhizome (approximately 20μm) was successfully reduced to 222.3 nm after the wet milling process. Higher degree of granules surface destruction occurred as a result of nanonization process based on FESEM image. Findings revealed that nanostructured ginger (NG) had the highest TPC and TFC which were 946.43 mgGAE/g and 20.16 mgQE/g followed by submicron ginger (SM) (712.68 mgGAE/g; 16.22 mgQE/g) and micron ginger (MG) (700.89 mgGAE/g; 14.45 mgQE/g) of dry matter respectively. Moreover, NG rhizome showed around 30 to 40% (p<0.05) greater radical scavenging activity as well as ferric reducing antioxidant power as compared to the other samples tested. The antioxidant activity was in the following in sequence: NG>SM>MG. Hence it can be concluded that reduction of particle size of ginger rhizome into nanoparticles using a wet milling process enhanced its antioxidant activity as compared to micron and submicron particles.
Authors: Hong Qi Li, Kai Xiang Tao, Hahn Choo, Peter K. Liaw
Abstract: The compressive behavior was investigated on an electrodeposited nanocrystalline Ni-20%Fe alloy with a grain size of about 22 nm at room temperature (RT), 298 K, and the liquid nitrogen temperature (LN2T), 77 K. The sensitivity of the yield strength and plastic strain to the test temperature at different grain sizes was discussed. Moreover, through the Transmission Electron Microscopy (TEM) examination and microhardness measurement, the microstructures before and after the compression test at RT and LN2T were studied.
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