Study Of Surface Microstructure Research Articles

Surface Microstructure Study of Self Cured Acrylic Resin after Immersion in Arabica Gayo Coffee

The water absorption on self-cured acrylic resin is higher than the heat cured acrylic resin. Incoming water positions itself between the polymer chains and affects the surface microstructure of self-cured acrylic resin. The absorption of liquids such as Arabica Gayo coffee may aggravate the surface structure of self-cured acrylic resins due to their acid content. This study aims to find out the microstructure of self-cured acrylic resin surface after immersed in Arabica Gayo coffee for 2 and 7 days. This study used 5 specimens of self-cured acrylic resin (MeliodentTM) with size 10x10x1,5 mm3. Each specimen was immersed in aquades for 24 hours to reduce the residual monomer and then be given different immersion treatments. The immersion temperature used was 55°C. After immersion, surface microstructure observation was done using Scanning Electron Microscope (JEOL JSM 6510 LA). The images obtained were bubbles after being immersed in aquades for 2 days and more on day 7, micro porous after being immersed in Arabica Gayo coffee for 2 days and more on day 7 than untreated specimens. The conclusion of this study is micro porous formed more on the surface of self-cured acrylic resin along with the duration of self-cured acrylic resin immersion in Arabica Gayo coffee.

Effect of SiC Reinforcement and Its Variation on the Mechanical Characteristics of AZ91 Composites.

In this study, the processing of SiC particulate-strengthened magnesium alloy metal matrix composites via vacuum supported inert atmosphere stir casting process is presented. The effects of small variations in the SiC particulate (average size 20 µm) reinforcement in magnesium alloy AZ91 were examined. It was found that with the addition of SiC particulate reinforcement, the hardness improved considerably, while the ultimate tensile and yield strength improved slightly. The density and porosity of the magnesium alloy-based composites increased with the increase in the wt.% of SiC particulates. The tensile and compressive fracture study of the fabricated composites was also performed. The tensile fractures were shown to be mixed-mode fractures (i.e., ductile and cleavage). The fractured surface also disclosed tiny dimples, micro-crack, and cleavage fractures which increases with increasing reinforcement. For the compression fracture, the surface microstructural studies of AZ91 displayed major shear failure and demonstrated the greater shear bands when compared to AZ91/SiC composites, which instead revealed rough fracture surfaces with mixed-mode brittle and shear features.

Machining parameters optimization of surface roughness analysis for AA5083 – Boron carbide (B4C) composites

This study concentrated to optimize the surface roughness analysis for the AA5083 – Boron carbide (B4C) composites with three process factors. The high strength aluminium alloy 5083 is considered for this study and increasing the strength by the reinforcement of boron carbide particles with different percentage of weight. The aluminium matrix composites are produced by the stir casting route. The stirring action implies 600 rpm constantly to increase the strength of the composite for improving the machining parameters. The optimization of machining (drilling) parameters for this study considered as drilling speed (1000 rpm, 1500 rpm and 2000 rpm), drilling feed (60 mm/min, 100 mm/min and 140 mm/min) and percentage of reinforcement (5%, 10% and 15%). The Design of experiments (DOE) is involved to find the minimum surface roughness of the composites efficiently, using the L9 OA to optimize the factors of the drilling operation. Surface microstructure study is conducted through 3D surface profilometry approach with the aid of gwyddion software.

Estudio comparativo de la nitrocarburación de los aceros AISI 4340 y AISI 347 mediante el proceso Tenifer-QPQ®

Este trabajo estudia las diferencias microestructurales y tribológicas de las capas formadas durante la nitrocarburación ferrítica del acero aleado AISI 4340 y la nitrocarburación austenítica del acero inoxidable estabilizado AISI 347. Las muestras se sometieron a distintos tiempos de inmersión en un baño de nitrocarburación (60, 75, 90, 105 y 120 min) a 580 ºC. Posteriormente se sometieron a un proceso de oxidación a 480 ºC para formar una capa de Fe3O4. Los estudios de la microestructura de la capa nitrocarburada se realizaron por microscopía electrónica de barrido (SEM), espectroscopía de dispersión de energías (EDS) y difracción de rayos X (XRD). Se estudió el desgaste y el coeficiente de fricción de las muestras nitrocarburadas y las muestras no tratadas mediante el ensayo pink-on disk. Los resultados muestran tres zonas bien diferenciadas en el acero AISI 4340: una capa de óxidos externa, una capa blanca o de combinación y zona de difusión. Sin embargo, no se detectó la presencia de la capa de combinación en el acero AISI 347. En ambos aceros, el coeficiente específico de desgaste (k) de las muestras nitrocarburadas fue aproximadamente treinta veces menor que el de las muestras de referencia.

Análise da liga quasicristalina Al62,2Cu25,3Fe12,5 para a reforma a vapor do metanol

<p>Este trabalho mostra o bom desempenho do quasicristal Al<sub>62,2</sub>Cu<sub>25,3</sub>Fe<sub>12,5</sub> como catalisador em reações catalíticas. Este catalisador metálico sem ser lixiviado com ácido ou base, a seco com composição estequiométrica de Al<sub>62,2</sub>Cu<sub>25,3</sub>Fe<sub>12,5</sub> revelou dentre as reações ocorrida haver uma oxidação parcial; cuja formação dos produtos foram metanol, metanal+ácido metanóico, água e éter dimétilico. Para esta pesquisa utilizou de técnicas experimentais como a Difração de Raios-X (DRX) para acompanhar a evolução das fases da liga, a Microscopia Eletrônica de Varredura (MEV) que permite o estudo de microestrutura de superfície, e a Microscopia Eletrônica de Transmissão (MET), estuda a morfologia de fases internas, núcleos quasicristalinos e defeitos; os testes catalíticos para conversão e seletividade de metanol e produtos formados a partir deste material usado como catalisador. A atividade e estabilidade do catalisador de quasicristal para a reformação do vapor de metanol mostrou uma desempenho suficiente em comparação aos demais catalisadores. As espécies Fe e Cu altamente dispersa na camada homogênea do catalisador quasicristal aumentam a atividade catalítica e suprime a agregação de Cu partículas. Neste artigo, se propusemos em analisar o quasicristal, como um bom catalisador para ser usado na reação de reforma a vapor, com elevada atividade catalítica e a excelente estabilidade térmica.</p>

Use Alloy Quasicrystalline Al62, 2cu25, 3fe12, 5 for Steam Reforming of Methanol

This study shows the good performance of quasicrystal Al62,2Cu25,3Fe12,5 as catalyst in catalytic reactions. The metal catalyst without being leached with acid or base with the stoichiometric composition of dry Al62,2Cu25,3Fe12,5 among the reactions shown to be a partial oxidation occurred , which formation of the products was methanol, methanal + methanoic acid, water and dimethyl ether. For this research used experimental techniques as X-Ray Diffraction-XRD to follow the evolution of the alloy phase, the Scanning Electron Microscopy-SEM allowing the study of surface microstructure, and Transmission Electron Microscopy-TEM studies the morphology of internal phase, and defects quasicrystalline nuclei; tests for the catalytic conversion of methanol and selectivity and products formed from this material used as catalyst. The activity and stability of catalyst quasicrystal for steam reforming of methanol showed sufficient performance compared to other catalysts. The Fe and Cu species highly dispersed in the homogeneous layer quasicrystal catalyst increases the catalytic activity and suppresses the aggregation of Cu particles. We propose that the quasicrystal can be a good catalyst to be used in catalytic steam reforming, with high catalytic activity and excellent thermal stability.

Surface Microstructure Study of Polyethylene Blends for Developing Environmental Degradable Plastic Bags

The morphology of the polymer blends retrieved from degradation experiments was investigated by studying the fractured surfaces using Scanning Electron Microscope for investigating the degradability of environmentally degradable plastic bags. We study the influence of adding photodegradable additives to film grade polyethylene under natural weathering conditions in Saudi Arabia. The films were exposed in outdoor environments located in Dhahran, Saudi Arabia. Comparison of different additives was determined and the additive PDQ-H shows the highest performance on the basis of degradation rate in the harsh environment of Saudi Arabian desert. DOI: http://dx.doi.org/10.3329/jce.v27i1.15847 Journal of Chemical Engineering, IEB Vol. ChE. 27, No. 1, June 2012: 8-11

Growth of molybdenum disulphide using iodine as transport material

In the present paper an attempt has been made to describe the chemical vapor transport (CVT) technique used for the growth of molybdenum disulphide (MoS2) single crystals. Iodine (I2) is used as transporting material for this purpose. The energy dispersive analysis by X-ray (EDAX) confirmed the stoichiometry of the as-grown crystals. The lattice parameters of these crystals were determined from the X-ray diffraction analysis. The grown crystals were examined under the optical zoom microscope for their surface microstructure study.

A methodology for combined palynological and molecular geochemical high-resolution analysis of lake sediments

Continuous lake sediment records are increasingly important for a detailed reconstruction of Holocene paleoenvironmental and paleoclimatic conditions. Currently a variety of biotic, isotopic and biochemical proxies are routinely applied in multidisciplinary reconstructions, to compensate for deficits of individual analytical approaches. High-resolution records that can show evidence for environmental change on centennial or decadal scales require the analysis of small-sized samples of only a few grams or less, which often limits the application of multiple techniques on one discrete sample. Here, we describe a novel procedure for sequential analysis of molecular biomarkers and subsequent determination of pollen distribution on a single, small sediment sample. Lipids were efficiently recovered from freeze-dried sediment using organic solvent mixtures of dichloromethane in hexane (1:5, v/v) or a mixture of dichloromethane/methanol (l:l, v/v) via accelerated solvent extraction at 100°C and 75 bar pressure. Solvent extraction was shown to have no effect on pollen preservation, including surface microstructure study by scanning electron microscopy analysis, or pollen distribution. Sample amounts of 5.1, 3.6 and 1.1 g that were processed in triplicate gave identical results for pollen and molecular biomarker distribution. The analytical approach is applicable to high-resolution studies where very small amounts of only 1 g of sample material are available.

Growth and transport properties of tin monosulphoselenide single crystals

The binary and ternary mixed single crystals of the orthorhombic IV–VI family in the form of SnS x Se 1− x (where x=0, 0.25, 0.50, 0.75 and 1) were grown by direct vapor transport technique. The lattice parameters of each grown crystal were determined from the X-ray diffraction analysis. The grown crystals were examined under the optical zoom microscope for their surface microstructure study. The low-temperature resistivity measurements were carried out in the temperature range 123–303 K using four-probe method. The Hall coefficient, carrier concentration and Hall mobility of each sample was determined from Hall effect measurements at room temperature. From the optical absorption spectra obtained in the range 1000–1500 nm, optical band gap of each sample was determined at room temperature. The results obtained are reported systematically.