Advances in Materials Sciences最新文献

{"title":"Lattice boltzmann modeling for mass and velocity fields of casting flows","authors":"Hu Zhi, Dong Anping, Du Dafan, Sun Dongke, Wang Donghong, Zhu Guoliang, Shu Da, Sun Baode","doi":"10.15761/ams.1000140","DOIUrl":"https://doi.org/10.15761/ams.1000140","url":null,"abstract":"The Lattice Boltzmann Method (LBM)-D2Q9 model is used to simulate velocity development and mass transfer of flows in casting. To quantify the basic flows in casting, stable flows in planes and pipes are simulated, which confirmed the LBM-D2Q9 model’s validation and numerical stability. Solute diffusion and vortex development are also investigated using LBM-D2Q9 model. The results show that the LBM model is capable to describe the velocity and solution field, which in a good match with the analytical calculations. *Correspondence to: Dong Anping, Shanghai Key Lab of advanced Hightemperature Materials and Precision Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China, Tel: +86 13817882779; E-mail: apdong@sjtu.edu.cn Received: June 28, 2018; Accepted: July 20, 2018; Published: July 23, 2018 Introduction The ongoing demanding of advanced aero engines, which possess high thrust and lightweight, have caused a tremendous application of the near net shape forming technology of complex thin-wall superalloy casts [1]. During the casting, the solidification sequence, temperature and solute concentration distribution are affected by the complexity of geometry shape and thinness of the cast wall. These’re bringing a challenge for cast perfect forming and metallurgical quality improvement. It has been found that counter-gravity casting with additional pressure is more capable for complex thin wall cast near net shape forming than regular gravity casting [2-3]. During the pressured counter-gravity casting, forming and solidification are experiencing forced convection and constrained space condition. The mechanisms of melt flow and crystallization and the relation of microflows between dendrites and porosity suppression and microstructure evolution are complicated and have been a top focused area in the solidification researches [3-5]. Lattice Boltzmann method (LBM) has been proved that is an effective and powerful method to gain a numerical solution of Navier-Stokes equation [6], compared to other traditional numerical solutions of the Navier-Stokes equation, like Lax-Wendroff, MacCormack or SIMPLE method. To reveal the solidification microstructure evolution of superalloy complex thin-wall casting under complex constrained space and forced convective condition, simulations of the mass and heat transfer and distribution in this complex constrained cast is needed to carry out to understand the solidification condition. In the first step, it’s our goal to verify the LBGK model for representing the basic thermo-flow in the casting. Lattice Boltzmann modeling In this work, Lattice Boltzmann Method (LBM) is adapted to simulate fluid flow, solute and heat transfer. The LBM is a discrete approximation of Boltzmann equation, based on gas kinetic theory. The BGK approximation, proposed by Bhatnagar, Gross and Krook who replaced the collision term J(ff1) by a single relaxation time Ωf [7], has been widely accepted an","PeriodicalId":408511,"journal":{"name":"Advances in Materials Sciences","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116865629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lipidic nanoparticules: a model function to predict the transition temperature of DPPC-DMPC mixtures","authors":"F. E. Buffo, M. B. Sierra, V. Pedroni, M. A. Morini","doi":"10.15761/AMS.1000117","DOIUrl":"https://doi.org/10.15761/AMS.1000117","url":null,"abstract":"Thermotropic behavior of unilamellar liposomes prepared from binary mixtures of phosphatidylcholines in aqueous suspensions was analyzed by means of the temperature dependence of the Zeta Potential (ZP). This technique presents high sensitivity and small amount of sample required, that is, 70% less than that required in the use of conventional calorimeters. A model function is proposed to adjust the thermotropic behavior of the DPPC-DMPC system. From the adjustment, temperature transition (Ttransition) data as a function of the composition are obtained. The objective of this paper is to propose, from those few Ttransition-composition data, a function that allows obtaining Ttransition for any composition of the mentioned system. Moreover, graph of phase boundaries for these mixed-lipid vesicles was constructed by plotting the delimiting temperatures of the main phase transition as a function of the lipid composition of the vesicle. The combination of the zeta potential technique and the mathematical processing of their data would be a simple and useful tool for determining the transition temperatures of more complex mixtures. Correspondence to: Laboratorio de Fisicoquímica, INQUISUR, Departamento de Química, Universidad Nacional del Sur (UNS)-CONICET, Av. Alem 1253, 8000 Bahía Blanca, Argentina , E-mail: mamorini@criba.edu.ar","PeriodicalId":408511,"journal":{"name":"Advances in Materials Sciences","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124403851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanoindentation of flexible graphite: experimental versus simulation studies","authors":"M. Khelifa, Fierro, J. Macutkevič, A. Celzard","doi":"10.15761/AMS.1000142","DOIUrl":"https://doi.org/10.15761/AMS.1000142","url":null,"abstract":"","PeriodicalId":408511,"journal":{"name":"Advances in Materials Sciences","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130456508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization and photocatalytic activity of N and Pt doped titania prepared by microemulsion technique","authors":"Wein-Duo Yang, Y. Hsu, Wen-Churng Lin, I-Lun Huang","doi":"10.15761/AMS.1000144","DOIUrl":"https://doi.org/10.15761/AMS.1000144","url":null,"abstract":"","PeriodicalId":408511,"journal":{"name":"Advances in Materials Sciences","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124013904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of TiO2 and ZnO on PLA degradation in various media","authors":"A. Marra, S. Cimmino, C. Silvestre","doi":"10.15761/AMS.1000122","DOIUrl":"https://doi.org/10.15761/AMS.1000122","url":null,"abstract":"This work shows the effect of 2 and 5 wt% TiO2 nanoparticles (modified by fluorocarbons and not) and of 1, 3 and 5 wt% ZnO particles on PLA degradation evaluated under UV irradiation, hydrolytical 1N NaOH solution, enzymatical proteinase K solution, and isothermal condition. The presence of TiO2 nanoparticles and ZnO particles decreases the degradation processes of PLA under UV light exposure and increases the PLA hydrolytic degradation. The enzymatic degradation is faster with TiO2 nanoparticles than with ZnO particles, respect neat PLA; whereas the opposite effect is identified in the PLA enzymatic degradation. Correspondence to: CAntonella Marra, Istituto per i Polimeri Compositi e Biomateriali (IPCB), Consiglio Nazionale delle Ricerche (CNR), Via Campi Flegrei 34, Comprensorio Olivetti, 80078 Pozzuoli (NA), Italy, E-mail: marranto.nella@libero.it","PeriodicalId":408511,"journal":{"name":"Advances in Materials Sciences","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127318450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Degradation study of used polystyrene with UV irradiation","authors":"Syed Sikandar Shah, I. Ahmad, M. Ishaq","doi":"10.15761/AMS.1000130","DOIUrl":"https://doi.org/10.15761/AMS.1000130","url":null,"abstract":"","PeriodicalId":408511,"journal":{"name":"Advances in Materials Sciences","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132280315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanohybrid materials from amine functionalization of sepiolite: Preparation, characterization and application as electrode modifiers for the electroanalytical detection of heavy metal ions","authors":"Ervice Ymélé, Jiokeng Z. L. Sherman, Tchieno M. M. Francis, I. Tonle","doi":"10.15761/AMS.1000133","DOIUrl":"https://doi.org/10.15761/AMS.1000133","url":null,"abstract":"Sepiolite-based organic–inorganic hybrid materials bearing amine groups were prepared by chemical grafting using 3-aminopropyltriethoxysilane (APTES) and [(3-(2-aminoethylamino)propyl)]trimethoxysilane (AEPTMS). The structural properties of the pristine sepiolite and the obtained composites materials were analysed using XRD, TG/DTA analysis and FTIR. The surface ion exchange ability of the functionalized clay minerals coated as thin film on glassy carbon electrodes and exposed to [Ru(NH3)6] or [Fe(CN)6] electroactive probes was also investigated by multisweep cyclic voltammetry (MSCV) and by Electrochemical impedance spectroscopy (EIS). From MSCV data, it was found that sepiolite and organosepiolites display a permselective behavior depending on the charge on its surface while EIS results showed that the functionalization of sepiolite enhanced its conductivity. The organosepiolites were tested in a comparative way for the voltammetric detection of mercury (II), and some preliminary experiments based on differential pulse voltammetry highlighted the interest of using the most sensitive organoclay (i.e. the sample grafted by AEPTMS) for the electroanalysis of several heavy metals in the same solution. Correspondence to: Ignas Kenfack Tonle, Chemistry of Materials and Electrochemistry, Department of Chemistry, Faculty of Science, University of Dschang, P.O. Box 67 Dschang, Cameroon, Tel: +237 696 141 545; Fax: +237 245 507 092; E-mail: ignas.tonle@univ-dschang.org","PeriodicalId":408511,"journal":{"name":"Advances in Materials Sciences","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132512406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural improvement of a bio-inspired 3D globular carbon foam by a continuously thermal treatment: A comprehensive study","authors":"J. Marx, H. Beisch, S. Garlof, B. Fiedler","doi":"10.15761/AMS.1000132","DOIUrl":"https://doi.org/10.15761/AMS.1000132","url":null,"abstract":"","PeriodicalId":408511,"journal":{"name":"Advances in Materials Sciences","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132821932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Isolation of cellulose nanofibrils from coconut waste for the production of sewing thread","authors":"M. Rojas-Valencia, Elsa Galeana-Olvera, D. Y. Fernández-Rojas, Christian Mendoza-Buenrostro, H. Nájera-Aguilar, M. Vaca-Mier","doi":"10.15761/AMS.1000135","DOIUrl":"https://doi.org/10.15761/AMS.1000135","url":null,"abstract":"Coconut waste is a by-product of commercial, industrial or agricultural activities, so that alternative uses for such waste are currently being sought. In Mexico, 66,203.22 tons of coconut waste were generated during the 2016 production cycle. Mexico City’s Central Market produces 108,000 kg/year of coconut fiber waste, which is sent directly to final disposal without being submitted to any type of treatment. Therefore, the general objective of this work was to find a way to use the cellulose nanofibrils obtained from coconut fiber residues to elaborate biomaterials that may substitute synthetic fibers in textile manufacturing. The methodology was divided into two phases. The first phase, performed in Mexico City’s Central Market, was field work focused on the study of the generation and sampling by quartering method based on Mexican Standard NMX-AA-15-1985. In the second phase, cellulose nanofibrils were obtained from the coconut fiber residues at laboratory level by means of a chemical method with sodium hydroxide. Subsequently, the cellulose nanofibrils were dissolved in a solution of 1-ethyl3-methylimidazolium acetate and N, N-dimethylformamide. Then, this solution was mixed with PCL and acetone and introduced in an electrospinning device. According to the results of proximate and cell wall analysis, coconut fiber waste contains 28.72% cellulose. It was determined that the solution containing 16% cellulose by weight was the most appropriate for yarn manufacturing purpose. Because of their high resistance to biodegradation and their durability, coconut fibers are a suitable material for obtaining cellulose nanofibrils that can be used in the textile industry. *Correspondence to: Neftalí Rojas-Valencia, National Autonomous University of Mexico, Institute of Engineering, Coordination of Environmental Engineering Building 5, cubicle 212, Avenida Universidad # 3000, Colonia Coyoacán, Distrito Federal, México, Tel: +55 52-56-23-36-00 ext. 8663; E-mail: nrov@ pumas.iingen.unam.mx","PeriodicalId":408511,"journal":{"name":"Advances in Materials Sciences","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114411626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Micromechanical and microstructural DEM modeling of the viscoelastic behavior of oil sands","authors":"E. Gbadam, S. Frimpong","doi":"10.15761/AMS.1000116","DOIUrl":"https://doi.org/10.15761/AMS.1000116","url":null,"abstract":"Oil sand is a composite material of quartz aggregates, bitumen, water, and air void in which the bitumen exhibits a time and temperature dependent behavior under loading. The soil skeleton (quartz aggregates) comprises dense, highly incompressible, uncemented fine interlocked grains exhibiting low in-situ void ratio, and high shear strengths and dilatancy under low normal stresses. In this work, a two-dimensional discrete element method (DEM) is developed to model the viscoelastic response of an oil sand formation. A digital sample of the oil sand with varying particle shapes and sizes were built using the discrete element software PFC2D. The oil sand microstructure was captured from an electron scanning micrograph image of a 14.5% bitumen content Athabasca oil sand. The micromechanical approach is based on discretizing the oil sands microstructure and modeling particle interactions (contacts) of its constituents at microscale. The quartz aggregates, water, and bitumen included in the digital samples were modeled using different contact models. Rheological data for the bitumen was obtained from a stress/strain controlled rheometer equipped with a parallel plate. This data was used to calibrate the parameters of the viscoelastic contact models among the different material phases. The resulting parameters of Burger’s model were used to simulate the micromechanical behavior of the material. A 2D DEM model with two temperatures and three loading frequencies subjected to a constant amplitude sinusoidal compression tests was simulated. The results of the study show a good agreement between the model prediction and the measured dynamic modulus and phase angle. This indicates that the linear viscoelastic DEM model developed is capable of simulating timedependent behavior of oil sands material. Additionally, the effect of rate of loading and temperature on the deformational mechanics of the material was evident in the dynamic modulus determination. Correspondence to: Samuel Frimpong, Department of Mining and Nuclear Engineering, Missouri University of Science and Technology, Rolla, MO 65401, USA, Tel: (573) 341-7617; Fax: (573) 341–6934; E-mail: frimpong@mst.edu Received: January 18, 2017; Accepted: February 26, 2017; Published: March 02, 2017 Introduction Oil sand is a dense granular material whose two main physical compositions are quartz grains and large quantities of interstitial bitumen, as shown in Figure 1. The pore spaces of oil sands are also filled with dissolved gasses and water [1-3]. The water is a thin film (~10 μm) that surrounds the quartz grains (about 99% water-wet) [4]. The connate water fills 10-15% of the pore spaces and the remaining is occupied by bitumen [1]. Figure 1(b) reveals that the grain-grain contact in oil sand formations exhibit mainly long and concavo-convex contacts. This structure is known as interpenetrative and is responsible for both the low void ratio and high shear strength [5]. Additionally, a large number of cont","PeriodicalId":408511,"journal":{"name":"Advances in Materials Sciences","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114353916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}