MRS Proceedings最新文献

{"title":"Preparation and characterization of UV-cured epoxy/clay nanocomposite coatings on carbon steel","authors":"J. L. V. Caselis, M. A. Sánchez, J. Aguilar, E. Rosas","doi":"10.1557/OPL.2016.77","DOIUrl":"https://doi.org/10.1557/OPL.2016.77","url":null,"abstract":"Polymer-clay nanocomposites are compounds in which nanoclay particles are distributed in a polymer matrix. Epoxy-clay nanocomposites have become a very interesting topic among researchers in the past two decades because nanoclays have a positive effect on the mechanical, thermal and especially barrier anticorrosive performance of the polymers. In this study, epoxy-montmorillonite organoclay (OMMT) nanocomposite coatings were prepared and deposited on carbon steel substrates. The coatings were prepared through in situ polymerization and by UV-curing technique. The OMMT was added to epoxy resin at loadings between 0 wt.% and 5 wt.%, the particles of OMMT were dispersed using forced agitation-sonication and deposited on carbon steel coupons. The nanocomposite coatings obtained have been characterized by scanning electron microscopy (SEM), spectroscopy Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and evaluated their corrosion protection effect on cold rolled carbon steel coupons by performing visual analysis. The X-ray analysis showed that exfoliation occurred for the OMMT in the polymer matrix, the SEM analysis showed that OMMT was homogenous dispersed in the polymer matrix and the coatings were uniform. The FTIR analysis showed the characteristic bands of epoxy resin and OMMT in the composite. The results showed that 1 wt.% OMMT coating exhibit better anticorrosive properties than pure epoxy.","PeriodicalId":18884,"journal":{"name":"MRS Proceedings","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75261645","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":"Soluble Silicates as Additives for Self-Sealing and Self-Healing Concrete","authors":"L. D. Miron, M. E. L. Magaña","doi":"10.1557/OPL.2016.7","DOIUrl":"https://doi.org/10.1557/OPL.2016.7","url":null,"abstract":"Tensile strength of concrete is limited and therefore is sensitive to crack formation. Steel reinforcement is added to bear the tensile forces; nonetheless, this does not completely omit crack formation. Repair of cracks in concrete is time-consuming and expensive. Self-sealing and self-healing of cracks upon appearance would therefore be a convenient property. We propose a mechanism to obtain self-repair of the concrete by adding soluble silicates (ASS) which will induce a self-sealing and self-healing process catalyzed by natural periods of wet and dry states of the concrete. Self-sealing approaches prevent the ingress of harsh chemical substances which may deteriorate the concrete matrix. This can be achieved by self-healing of concrete cracks (e.g. further cement hydration, calcium carbonate precipitation) and autonomous healing (e.g. further hydration of partially soluble silicates added as healing agents). The autogenous healing efficiency depends on the amount of deposited reaction products (ASS), its solubility (ratio of calcium to sodium silicate), the availability of water, and the crack width (restricted by adding microfibers). The self-sealing efficiency is generally evaluated by measuring the decrease in water permeability and air flow through the crack. The healing efficiency is usually evaluated by testing concrete´s regain in mechanical properties after crack formation; by reloading the cracked and autonomously healed specimen and comparing the obtained mechanical properties with the original ones. Self-sealing and self-healing of concrete gives a broad perspective and new possibilities to make future concrete structures more durable.","PeriodicalId":18884,"journal":{"name":"MRS Proceedings","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81885970","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":"Remote Measurement of Linear Polarization Resistance In Concrete Structures","authors":"F. B. Castillo, W. Aperador, G. Roa-Rodríguez","doi":"10.1557/opl.2016.95","DOIUrl":"https://doi.org/10.1557/opl.2016.95","url":null,"abstract":"","PeriodicalId":18884,"journal":{"name":"MRS Proceedings","volume":"143 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79844468","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 Niobium on the Microstructure of High Chromium White Cast Iron","authors":"C. D. Oliveira, I. P. Pinheiro","doi":"10.1557/OPL.2016.65","DOIUrl":"https://doi.org/10.1557/OPL.2016.65","url":null,"abstract":"Equipment wear is caused by the disintegration of material due to the contact between the machines components and the ore, resulting in stress to the surface of the material. Wear causes loss of efficiency, vibration, misalignment and, in severe cases, cracks that may lead to fracture and damage to the equipment. In mining, wear is caused by operational problems in which generate high costs. Some researchers studied white cast iron alloys with high chromium and the addition of niobium for wear plates manufacturing and therefore, plates to protect structural parts of the equipment have been developed. This study presents the characterization of the microstructure of two alloys of white cast iron with high chromium containing 3.8 wt.% C and 27.1 wt.% Cr and the addition of 0.9 wt.% Nb (alloy 1) and 1.6 wt.% Nb (alloy 2), respectively. Samples of the two alloys were subjected to metallographic tests, microhardness and abrasion type rubber wheel tests, according to the ASTM: G65-91 standard. Complexes carbides have been identified in both alloys. The results of microhardness and wear resistance tests were correlated and identified the effect of niobium addition. The findings suggest that the addition of niobium in these alloys contributes to the formation of NbC and increase of Cr in the matrix; consequently increase in the hardenability of the material. The wear resistance of alloy 2 was 47.95% higher than alloy 1 in abrasion type rubber wheel tests. It demonstrates that the increase of niobium in the alloy has contributed to improve wear resistance due to the substantial change in the microstructure and distribution of NbC carbides.","PeriodicalId":18884,"journal":{"name":"MRS Proceedings","volume":"88 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88564870","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":"Synthesis and characterization of new materials with pyrrole units and their semiconductor behavior","authors":"Olivia Monroy, L. Fomina, R. Salcedo","doi":"10.1557/OPL.2016.75","DOIUrl":"https://doi.org/10.1557/OPL.2016.75","url":null,"abstract":"New organic materials with semiconductor behavior were prepared from diphenyldiacetylene and aromatic amines with withdrawing groups by Reisch-Schulte reaction and characterized by IR, RMN spectroscopy. The obtained materials share the property of having electron withdrawing groups joint to the attached aromatic ring, it seems this feature accounts in large fashion to improve the semiconducting behavior of this kind of substances, this topic was studied by means theoretical calculations and the results are also discussed. The calculations were carried out by means the Gaussian09 software and all the involved species were geometrically optimized.","PeriodicalId":18884,"journal":{"name":"MRS Proceedings","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86394047","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":"Study of Photoluminescence Properties of CuxO Thin Films Prepared by Reactive Radio Frequency Magnetron Sputtering","authors":"Jiantuo Gan, A. Galeckas, V. Venkatachalapathy, H. N. Riise, B. Svensson, E. Monakhov","doi":"10.1557/OPL.2015.596","DOIUrl":"https://doi.org/10.1557/OPL.2015.596","url":null,"abstract":"CuxO thin films have been deposited on a quartz substrate by reactive radio frequency (rf) magnetron sputtering at different target powers Pt (140-190 W) while keeping other growth process parameters fixed. Room-temperature photoluminescence (PL) measurements indicate considerable improvement of crystallinity for the films deposited at Pt>170 W, with most pronounced excitonic features being observed in the film grown using Pt=190 W. These results corroborate well with the surface morphology of the films, which was found more flat, smooth and homogeneous for Pt >170 W films in comparison with those deposited at lower powers.","PeriodicalId":18884,"journal":{"name":"MRS Proceedings","volume":"1 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86769614","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":"MOCVD of a Nanocomposite Film of Fe, Fe 3 O 4 and Carbon Nanotubes from Ferric Acetylacetonate: Novel Thermodynamic Modeling to Reconcile with Experiment","authors":"S. Dhar, Pallavi Arod, K. Achari, S. Shivashankar","doi":"10.1557/OPL.2015.7","DOIUrl":"https://doi.org/10.1557/OPL.2015.7","url":null,"abstract":"Thermodynamic modeling of the MOCVD process, using the standard free energy minimization algorithm, cannot always explain the deposition of hybrid films that occurs. The present investigation explores a modification of the procedure to account for the observed simultaneous deposition of metallic iron, Fe 3 O 4 , and carbon nanotubes from a single precursor. Such composite films have potential application in various device architectures and sensors, and are being studied as electrode material in energy storage devices such as lithium ion batteries and supercapacitors. With ferric acetylacetonate [Fe(acac) 3 ] as the precursor, MOCVD in argon ambient results in a nanocomposite of CNT, Fe, and Fe 3 O 4 (characterized by XRD and Raman spectroscopy) when growth temperature T and total reactor pressure P are in the range from 600°C-800°C and 5-30 torr, respectively. No previous report could be found on the single-step formation of a CNT-metal-metal oxide composite. Equilibrium thermodynamic modeling using available software predicts the deposition of only Fe 3 C and carbon, without any co-deposition of Fe and Fe 3 O 4 , in contrast with experimental observations. To reconcile this contradiction, the modeling of the process was approached by taking the molecular structure of the precursor into account, whereas “standard” thermodynamic simulations are restricted to the total number of atoms of each element in the reactant(s) as the input. When O con (statistical average of the oxygen atom(s) taken up by each metal atom during CVD) is restricted to lie between 0 and 1, thermodynamic computations predict simultaneous deposition of FeO 1-x , Fe 3 C, Fe 3 O 4 and C in the inert ambient. At high temperature and in a carbon-rich atmosphere, iron carbide decomposes to iron and carbon. Furthermore, FeO 1-x yields Fe and Fe 3 O 4 when cooled below 567°C. Therefore, the resulting film would be composed of Fe 3 O 4 , Fe and C, in agreement with experiment. The weight percentage of carbon (∼40%) calculated from thermodynamic analysis matches well with experimental data from TG-DTA.","PeriodicalId":18884,"journal":{"name":"MRS Proceedings","volume":"17 1","pages":"45-50"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83798716","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":"Automated Reel-to-Reel Fluidic Self-Assembly for the Production of Solid State Lighting Modules","authors":"Se‐Chul Park, Jun Fang, Shantonu Biswas, Mahsa Mozafari, T. Stauden, H. Jacobs","doi":"10.1557/OPL.2015.679","DOIUrl":"https://doi.org/10.1557/OPL.2015.679","url":null,"abstract":"We report the implementation of an automated reel-to-reel fluidic self-assembly system based on surface-tension driven self-assembly for macroelectronics application. The reported system incorporates precisely controlled and automated agitation, web moving, component recycling, and dispensing system. The system enables continuous parallel assembly of semiconductor chips at a high rate (15,000 chips per hour using 2.5 cm wide web) and assembly yield (>99%) under optimal condition. In principle, scaling to any throughput should be possible considering the parallel nature of self-assembly. The process overcomes the limitations on area and throughput of prior methods. It provides a new platform for macroelectronics to enable the integration of microscopic high performance inorganic semiconductors on flexible substrates with any desired location, pitch, and integration density. As an example we demonstrate the fabrication of a solid state area lighting module.","PeriodicalId":18884,"journal":{"name":"MRS Proceedings","volume":"9 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87963322","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":"Deformable Microsystem for In Situ Cure Degree Monitoring of GFRP (Glass Fiber Reinforced Plastic)","authors":"Yang Yang, G. Chiesura, T. Vervust, F. Bossuyt, G. Luyckx, Markus Kaufmann, J. Degrieck, J. Vanfleteren","doi":"10.1557/OPL.2015.790","DOIUrl":"https://doi.org/10.1557/OPL.2015.790","url":null,"abstract":"Fibre Reinforced Polymer (FRP) is becoming a valid alternative to many traditional heavy metal industries because of its high specific stiffness over the more classical construction metals. Recent trend of more complex geometry of composites is causing increasing difficulty in composite manufacturing. A method to optimize the manufacturing process is thus imposed to ensure and improve the quality of manufactured parts. Because of the irregular 3D shapes of the composites, traditional flat sensor system is becoming unfavorable and nonpractical for monitoring purpose. In this work, the current development status of a deformable microsystem for in situ cure degree monitoring of a glass fibre reinforced plastic is presented. To accommodate the non-flat shape of the composites, the proposal is to interconnect non-deformable functional island, which contains the capacitive sensor for cure degree monitoring, with meander-shaped deformable interconnections. The developed sensor system is able to withstand the manufacturing process where change of pressure and internal strain, thus force exerted on the sensor system, is involved.","PeriodicalId":18884,"journal":{"name":"MRS Proceedings","volume":"25 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84139707","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 Evolution of AuPt and AuPd Nanoparticles Fabricated by Microwave Assisted Synthesis: A Comparative Study","authors":"T. Som, R. Wendt, S. Raoux, J. Jordan-Sweet, M. Wollgarten, K. Rademann","doi":"10.1557/OPL.2015.383","DOIUrl":"https://doi.org/10.1557/OPL.2015.383","url":null,"abstract":"Bimetallic nanoparticles (NPs), particularly Au/Pd and Au/Pt, have attracted extensive attention due to their wide-spread application in catalysis, optoelectronics and energy recuperation.[1] Here we have attempted the fabrication of Au/Pt and Au/Pd bimetallic NPs by an energy-efficient eco-friendly microwave methodology. The microwave-assisted reactions enable considerably large product yields over conventional colloidal methods due to (a) almost two-fold increased reaction kinetics, (b) localized superheating at reaction sites and rapid rise of initial temperature.[2] Au NPs (sizes 20 ± 3 nm) are fabricated in the first step followed by the reduction of [PdCl2(NH3)2] or [K2PtCl6]in tetraethylene glycol at 180 oC for 2 min. Controlling and understanding the atomic structure and elemental distributions of these NPs are crucial for their optimized performances. So, we address the fundamental question of the most likely arrangement of Au and Pd or Pt atoms in these bimetallic NPs prepared under similar conditions by complementary characterizations using UV-Vis spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The UV-Vis spectroscopy reveals the formation of an alloy shell. The extent of depression of the plasmon peak of Au and its blue-shift reveals substantial deposition of Pd atoms on an Au core and significant alloying in comparison to Au/Pt NPs. XRD reveals the gradual shift of the diffraction peak from the position of Au to the position of Pd or Pt with change in composition. XRD supports the formation of a thick alloy shell in these NPs. However, the TEM images reveal a very interesting result. With increase in Pt concentration, the size of the dispersed NPs decreases from 20 ± 3 nm to about 16 nm (± 1 nm) and there is evolution of a bimodal particle size distribution with small particles about 1-2 nm diameters. On the contrary, with increasing Pd concentration, the particle size of the dispersed particles increases to about 32 nm (± 1 nm). This discrepancy of particle size evolution for the two systems arises due to the differences in surface energies (Pt > Pd > Au atoms). Pt atoms tend to diffuse towards the core with the formation of Au nano-islands which eventually segregates leading to a reduction in particle size and bimodal distribution. At higher concentration of Pt, Pt and Au atoms tend to nucleate separately also contribute to the bimodal distribution. While for Au/Pd NPs, we have an Au core with an alloyed shell having higher Pd concentration. This is further supported by experimental evidence by selective etching and dissolution of Au by potassium-iodide solution. Furthermore, the Au/Pd bimetallic NPs are found to possess better catalytic activities in the reduction of 4-nitrophenol to 4-aminophenol than Au/Pt and monometallic NPs.","PeriodicalId":18884,"journal":{"name":"MRS Proceedings","volume":"52 1","pages":"13-18"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79759766","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}