Papers by Keyword: Particle Size Effect

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Authors: Lin Geng, Yi Wu Yan
Abstract: The coefficients of thermal expansion (CTEs) of the 20 vol% SiCp/Al composites fabricated by powder metallurgy process were measured and examined from room temperature to 450°C The SiC particles are in three nominal sizes 5μm, 20μm and 56μm. The CTEs of the SiCp/Al composites were shown to be apparently dependent on the particle size. That the larger particle size, the higher CTEs of the composites, is thought to be due to the difference in original thermal residual stresses and matrix plasticity during thermal loading. The thermal conductivity of the composites also increases with particle size increasing.
Authors: Yi Wu Yan, Lin Geng, Ai Bin Li, Guo Hua Fan
Abstract: By incorporating the Taylor-based nonlocal theory of plasticity, the finite element method (FEM) is applied to investigate the effect of particle size on the deformation behavior of the metal matrix composites. In the simulation, the two-dimensional plane strain and random distribution multi-particles model are used. It is shown that, at a fixed particle volume fraction, there is a close relationship between the particle size and the deformation behavior of the composites. The yield strength and plastic work hardening rate of the composites increase with decreasing particle size. The predicted stress-strain behaviors of the composites are qualitative agreement with the experimental results.
Authors: Young Soon Kwon, Pyuck Pa Choi, Ji Soon Kim, Dae Hwan Kwon, K.B. Gerasimov
Abstract: The particle size effect on the peritectic melting of FeSn2 particles in FeSn-FeSn2 nanocomposites was studied using differential scanning calorimetry and X-ray diffraction. FeSn-10 wt.% FeSn2 compounds, mechanically milled for 30 min and slowly heated in a differential scanning calorimeter, showed incongruent melting at 680 K. Although FeSn2 grains grew from 10 to 40 nm upon heating before peritectic melting set in, the melting temperature was more than 100 K lower than the equilibrium value. A small latent heat during peritectic melting and a large amount of interfacial energy of FeSn-FeSn2 nanocomposites are held responsible for this large particle size effect. Grain growth is hardly possible in the case of rapid local heating during mechanical milling. Therefore, a decrease in the peritectic melting temperature is even expected to be substantially larger.
Authors: Karol Campos, Eric Guibal, Francisco Peirano, M. Ly, Holger Maldonado
Abstract: Mercury sorption on chitosan was investigated in batch and continuous systems. Chitosan sorption properties were determined through sorption isotherms. Langmuir and Freundlich equations were used for the modeling of isotherms at pH 5. In batch systems, maximum sorption capacities reached 550 mg Hg/g. Sorption kinetics have been studied as a function of sorbent particle size and stirring rate. Dynamic removal of mercury was tested in a fixed bed reactor investigating the following parameters: particle size, column size, flow velocity and metal ion concentration. Clark and Adams-Bohart models were evaluated for the simulation of breakthrough curves. This study shows that chitosan is an effective sorbent for the treatment and recovery of mercury from dilute effluents at near neutral pH.
Authors: Chong Yau Wong, Joan Boulanger, Gregory Short
Abstract: It is known that particle size has an influence in determining the erosion rate, and hence equipment life, on a target material in single phase flows (i.e. flow of solid particles in liquid only or gas only flows). In reality single phase flow is rarely the case for field applications in the oil and gas industry. Field cases are typically multiphase in nature, with volumetric combinations of gas, liquid and sand. Erosion predictions of multiphase flows extrapolated from single phase flow results may be overly conservative. Current understanding of particle size distribution on material erosion in multiphase flows is limited. This work examines the effect of particle size distribution on material erosion of a cylindrical aluminium rod positioned in a 2" vertical pipe under slug and distributed bubble regimes using various water and air volume ratios. This is achieved through physical erosion experiments and computational fluid dynamics (CFD) simulations tailored to account for particle dynamics in multiphase flows.
Authors: Man Yang, Xian Feng Chen, Yu Jiao Shang, Ren Dong Bao
Abstract: In order to evaluate the effect of particle size on FeS Spontaneous Combustion Characters, four different grain diameters of FeS particles (100, 170, 220, 320-mesh) were detected in the experiment. The reaction process at heating rates of 5°C /min in air flow from 30°C to 900°C were studied by TG-DSC and oxidation kinetic analysis. The activation energies of samples were calculated by the Coats-Redfern method. It is found that four reaction mechanisms are involved in FeS spontaneous combustion for different particle sizes; the activation energy values change from 307.4 to 398.05 kJ/mol; larger size particles have higher activation energy values; so grain diameters larger than 100-mesh size samples are less inclined to be oxidized and self-ignited.
Authors: A.V. Tripković, V. Jovanović, J.D. Lović, K.Dj. Popović, A. Kowal
Abstract: The methanol oxidation was studied at two differently prepared supported Pt electrodes (Pt-C/GC and Pt/GC) in 0.5 M H2SO4 and 0.1 M NaOH. The supported Pt electrodes were characterized by AFM, STM TEM and HRTEM. The higher activity of Pt-C/GC than of Pt/GC catalyst, as well as negligible differences in the activities between the supported Pt catalysts and the corresponding single crystal electrodes oriented as the sites in the catalyst deposits in which Pt particles are dominant, clearly suggest the influence of the particle size effect on the catalyst activity.
Authors: Wan Fahmin Faiz Wan Ali, Norazharuddin Shah Abdullah, Mohd Fadzil Ain, Zainal Arifin Ahmad
Abstract: The phase evolution of yttrium iron garnet (YIG) during reaction 3Y2O3-5Fe2O3 was investigated by modifying Fe2O3 particle sizes (FPS). Five different sizes of Fe2O3, (d50) are used to prepare YIG powder. Solid state reaction (SSR) was applied at 1200 °C in order to gain insight on the effect of FPS towards the YIG formation. Rietveld refinement method was used to quantify the amount of YIG yielded (%). Larger FPS (> 50 μm) initiates only 5Fe2O3 + 3Y2O3 à 3YFeO3 + Fe2O3 + Y3Fe5O12.. However, when the fine FPS (5 μm) is used, the reaction pathway was changed into 5Fe2O3 + 3Y2O3 à 6YFeO3 + 2Fe2O3 à 2Y3Fe5O12. These behaviors is explained that the smaller FPS consumed quickly to form YIG due to the smaller particle distance between Fe2O3 and Y2O3. This shall be leading to higher reaction rates (mass-transfer kinetics).
Authors: Ali Sadrmomtazi, O. Alidoust, Akbar K. Haghi
Abstract: The amount of waste glass sent to landfill has increased over recent years due to an ever growing use of glass products. Landfilling can cause major environmental problems because the glass is not biodegradable material. However, waste glass can be used as fine aggregate, coarse aggregate and powder form in concrete. The fine and coarse aggregate can cause alkali-silica reaction (ASR) in concrete, but the powder form can suppress their ASR tendency and acts as a pozzolanic material. This paper studies the expansion properties in concrete containing waste glass, silica fume, rice husk ash and polypropylene fibers in detail.
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