Metallurgy Commons^™

Influence Of Microstructural Length Scale On Deformation Behavior Of Magnesium Alloys, Wei Yuan

Doctoral Dissertations

"Friction stir processing (FSP) is emerging as an effective tool for microstructural modification. Mg-Al-Zn alloys with different aluminum contents were subjected to FSP to achieve fine grained and ultrafine grained (UFG) structure. The objective of this work was to study the influence of microstructural length scale on the governing deformation and strengthening mechanisms of FSP magnesium alloys.

FSP introduced strong basal fiber texture and processing parameter dependent grain/precipitate size and distribution. Grain refinement promoted non-basal dislocation activation at room temperature. The strength of the alloy increased as a consequence of grain refinement following classic Hall-Petch relationship to different extents due …

Influence Of Grain Size And Texture On Hall-Petch Relationship For A Magnesium Alloy, W. Yuan, S. K. Panigrahi, J. Q. Su, R. S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

Friction stir processing was applied to a magnesium alloy to generate various grain sizes with the same intense basal texture. Subsequent tensile deformation along two orthogonal directions by easy activation or inhibition of basal slip follows the Hall-Petch relationship between yield stress and grain size in both directions. the Hall-Petch parameters are texture dependent. Easy activation of basal slip introduces lower values, while inhibition of basal slip leads to higher values. the Hall-Petch parameters are interpreted by texture and microstructural factors. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Grain Boundary Behavior In An Ultrafine-Grained Aluminum Alloy, P. S. De, R. S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

The low-angle grain boundary (LAGB) stability in an ultrafine-grained (UFG) Al alloy during monotonic loading was investigated by orientation imaging microscopy (OIM). the experiments show that boundaries with misorientation below ∼2.5 deg are stable, while boundaries with misorientation between 2.5 and 15 deg are unstable. Similar results were observed during cyclic loading of UFG Al alloy. This behavior was rationalized using the nonequilibrium thermodynamics concept. on the other hand, it is postulated that the grain boundary behavior in microcrystalline alloy is different because of the larger dislocation mean free path. © 2011 the Minerals, Metals & Materials Society and ASM …

Spark Plasma Sintering Of Tungsten And Tungsten-Ceria: Microstructures And Kinetics, Jeffrey Bryce Perkins

Boise State University Theses and Dissertations

Tungsten casting is impractical, and tungsten compacts are most often produced by press-and-sinter or by hot pressing. The temperatures typically required to sinter tungsten above 90% dense are above 1800 ºC, and sintering times are typically hours. Alternatively, spark plasma sintering (SPS) can be used to consolidate materials to high densities at lower temperatures and shorter times than traditional sintering techniques. In this study, pure tungsten and tungsten with 1, 4, 10, 15, and 20 weight percent ceria were spark plasma sintered at varying pressures, temperatures, and times to investigate the microstructures and the kinetics of sintering.

Densification of tungsten …

Modeling And Control Of A Flexible Ionic Polymer Metal Composite(Ipmc) Actuator For Underwater Propulsion, Shivakanth Gutta

UNLV Theses, Dissertations, Professional Papers, and Capstones

The goal of this research is to model and control the underwater vehicle propelled by IPMC actuator. IPMC consists of an ionic membrane sandwiched between two metallic electrodes. When an external voltage is applied, IPMC undergoes large deformation due to transport of ions. Due to its ability to work in aqueous environments, it can be used for developing small scale underwater vehicles.

First, Finite element approach is used to describe the dynamics of the both single and segmented IPMC actuator. In the approach presented, each element is attached with a local coordinate system that undergoes rigid body motion along with …

Flexible Connection Elastomeric Rubber As A Pounding Resisting Element Between Two Adjacent Buildings, Yuskar Lase, James Jatmiko Oetomo

Makara Journal of Technology

Flexible Connection Elastomeric Rubber as a Pounding Resisting Element between Two Adjacent Buildings To solve pounding problem of two adjacent buildings, structural designer usually employs a dilatation between the structures or make the two structures as a monolith structure. Other alternative is by using an elastomeric rubber as a pounding resisting element between the two structures. Effectiveness in applying elastomeric rubber component as flexible connection of two adjacent structures is the main focus of this paper. Various simulations such as structure models, earthquake excitations and openings in gap element are studied. Observation of maximum structural responses will be performed for …

Improvement Of High Temperature Oxidation Of Low Carbon Steel Exposed To Ethanol Combustion Product At 700 °C By Hot-Dip Aluminizing Coating, Mohammad Badaruddin

Makara Journal of Technology

Low carbon steel (AISI 1005) was coated by hot-dipping into a molten Al-10% Si bath at 700 °C for 18s. After hotdipping treatment, the coating layers consisted of Al, Si, FeAl3, τ5-Fe2Al8Si, and Fe2Al5. The bare steel and the aluminized steel were isothermally oxidized at 700 °C in ethanol combustion product at atmospheric pressure for 49 h. The aluminized steel shows good performance in high temperature oxidation because the formation of Al2O3 layer on the coating surface. The growth of iron oxide nodules on the surface coating was accelerated by rapid outward diffusion of Fe-ions due to the presence of …

Effect Of Copper Addition On Mechanical Properties And Electrical Conductivity Of Pp/C-Cu Bipolar Plate Composites, Anne Zulfia, Taufik Abimanyu, Verina Warga Dalam

Makara Journal of Technology

Effect of Copper Addition on Mechanical Properties and Electrical Conductivity of PP/C-Cu Bipolar Plate Composites. Bipolar plate is a major component in PEM fuel cell which possess main function of collecting and removing electrons from anode to cathode. Therefore, materials for bipolar plates produced must have high electrical conductivity. To obtain bipolar plate materials which is cheap, lightweight and high conductivity, so it is developed bipolar plates material based on PP/C-Cu composite. PP/C-Cu composites has been made by mixing all materials then compounding, rheomix, hot blending and hot press. Cu (Copper) has been used various from 0.1 wt%, 1 wt% …

Application Of Principal Component Proximity Transform And Geostatistics Methods For Volume Shale Distribution As Reservoir Characreristic Imaging In Seismic 3d, Nur Islami

Makara Journal of Technology

Application of Principal Component Proximity Transform and Geostatistics Methods for Volume Shale Distribution as Reservoir Characreristic Imaging in Seismic 3D. Principal component proximity transform (PCPT) technique was used to predict the content of volume shale into seismic data in reservoir modeling framework. The goal in this research is to get the volume shale imaging in three dimensions and allow for reservoir modelling. The reservoir modelling requires an integrated quantitative and qualitative data sources collected separately, such as well and seismic data. Integrating PCPT and Geostatistic methods can generate the detail information for characterization of reservoir’s properties. Finally, it shows that …

Application Of Empirical Orthogonal Function Models To Analyze Shoreline Change At Bangkalan Madura, Darius Arkwright, Suntoyo Suntoyo

Makara Journal of Technology

Bangkalan’s shoreline, especially on the opposite side of Surabaya, has been evaluated to determine the morphological changes due to wave attack, near-shore current, long-shore sediment transport and coastal configuration. This research aims to determine the dominant patterns of variation of Bangkalan’s shoreline change, expressed by Eigen-function in empirical orthogonal function (EOF) models. That was started with data collection such as oceanographic data (wave and tidal), bathymetry and topographic map and sediment data. All data was used for forecasting two-monthly shoreline. Coordinate of two-monthly shoreline was used as input of EOF model. The first Eigen mode is a profile of shoreline …

Establishment Code Hand Palm (Palm Code) 2d Gabor-Based Method, I Ketut Gede Darma Putra, Wira Bhuana, Erdiawan Erdiawan

Makara Journal of Technology

Establishment Code Hand Palm (Palm Code) 2D Gabor-Based Method. Palmprint is relatively new in physiological biometrics. Palmprint ROI segmentation and feature extraction are two important issues in palm print recognition. This paper introduces two steps in the center of mass moment method for ROI segmentation that will be applied in the Gabor 2D filter to obtain palm code as palmprint feature vector. Normalized Hamming distance was used to measure the similarity degrees of two feature vectors of palmprint. The system was tested using database 1000 palmprint images generated from 5 samples from each of the 200 persons randomly selected with …

The Effectiveness Of Anaerobic Baffled Reactor And Rotating Biological Contactor In Batik Wastewater Treatment, Augustinus Ignatius Kristijanto, Widhi Handayani, Purwanti Asih Anna Levi

Makara Journal of Technology

Batik is one of popular arts of Indonesia. The batik industries in Sragen, Central Java, are prepared to compete in global market. In order to realize that objective, batik products should fulfill some qualifications, one of which is “environmental friendliness”. As batik production is usually generating wastewater which pollutes the environment, the technology of wastewater treatment should be developed to solve the problem. This preliminary study has been done to assess the effectiveness of anaerobic baffled reactor (ABR) and rotating biological contactor (RBC) in batik wastewater treatment. In 40 days of treatment period, the ABR performance in reducing pollutants showed …

Physical Characterization And Desulfurization Of Biobriquette Using Calcium-Based Adsorbent, Mahidin Mahidin, Asri Gani, Khairil Khairil

Makara Journal of Technology

Combustion of coal and co-combustion of their co-fuel contribute to gas emissions. Among the gas emissions are SOx, NOx, CO and CO2. Introduction of calcium based adsorbent is addressed to absorb SO2 that release to the atmosphere during the combustion process. Objective of the research is at first to observe the physical characteristics of biobriquettes as a function of briquette compositions (coal to palm kernel shell ratios) and Ca/S ratios (Ca in adsorbent and S in briquette) using a natural adsorbent (shellfish waste). The second objective is to investigate desulfurization characteristics as a function of Ca/S ratios and desulfurization temperatures …

Flutter Analysis Of Rx-420 Balistic Rocket Fin Involving Rigid Body Modes Of Rocket Structures, Novi Andria

Makara Journal of Technology

Flutter Analysis of RX-420 Balistic Rocket Fin Involving Rigid Body Modes of Rocket Structures. Flutter is a phenomenon that has brought a catastrophic failure to the flight vehicle structure. In this experiment, flutter was analyzed for its symmetric and antisymmetric configuration to understand the effect of rocket rigid modes to the fin flutter characteristic. This research was also expected to find out the safety level of RX-420 structure design. The analysis was performed using half rocket model. Fin structure used in this research was a fin which has semispan 600 mm, thickness 12 mm, chord root 700 mm, chord tip …

Analytical And Computational Simulation Approaches To Design Low Energy Glass Block, Floriberta Binarti, Agustinus Djoko Istiadji, Prasasto Satwiko, Priyo Tri Iswanto

Makara Journal of Technology

Analytical and Computational Simulation Approaches to Design Low Energy Glass Block. An environmentally friendly process was developed to produce a low embodied energy glass block from waste glasses. The energy efficiency of the glass block is represented by its thermal conductance (U)

Medium Density Fibreboard Made Of Acetylated Sludge From Paper Mill, Luthfi Hakim, Evalina Herawati, I Nyoman Jaya Wistara

Makara Journal of Technology

Medium Density Fibreboard Made of Acetylated Sludge from Paper Mill. Research of using sludge as raw material for making medium density fibreboard (MDF) was useful to create additional value of sludge. The objective of the research was to evaluate physical properties, mechanical properties, and durability of MDF from acetylated sludge in 4 levels of acetate anhydride (0%, 3%, 5%, and 7%) with 3 replicates. The MDF was made using dry process. After materials were mixed with adhesives, they were pressed using hotpress under 170 oC temperature and 45 Pa pressure for 25 minutes. The size of the MDF sample was …

Optimation Of Nitrogen And Phosphorus In Azolla Growth As Biofertilizer, Hany Handajani

Makara Journal of Technology

Nitrogen is one of the most important minerals for living organisms. Azolla is known as a small water fern which can fix nitrogen through the symbiotic association with the blue green algae Anabaena. Experimental studies were carried out in the glass house, investigating the growth of Azolla using different levels of nitrogen and phosphorus in the media. The experiment used 12 treatments with 3 levels of nitrogen (0, 5, and 10 mg atom/L) and 4 levels of phosphorus (0, 10, 20, and 30 mg atom/l) in a factorial design with 3 replicates. The results show that the highest biomass for …

Antibacterial Activity Of Papaya Leaf Extracts Against Pathogenic Bacteria, Elisa Friska Romasi, Jessica Karina, Adolf Jan Nexson Parhusip

Makara Journal of Technology

It was reported that the extracts of papaya leaves could inhibit the growth of Rhizopus stolonifer. Antibacterial activity of Carica papaya leaf extracts on pathogenic bacteria was observed in this study. Papaya leaves were extracted by using maceration method and three kinds of solvents: ethanol, ethyl acetate, and hexane. Papaya leaf extracts were tested against Bacillus stearothermophilus, Listeria monocytogenes, Pseudomonas sp., and Escherichia coli by agar diffusion method. The objectives of this study were to determine extract ability against pathogenic bacteria, to observe the influence of pH, NaCl, and heat on extracts ability, and to observe extract ability against B. …

Cassava Pulp As A Biofuel Feedstock Of An Enzymatic Hydrolysis Proces, Djuma’Ali Djuma’Ali, Nonot Soewarno, Sumarno Sumarno, Dyah Primarini, Wahono Sumaryono

Makara Journal of Technology

Cassava pulp, a low cost solid byproduct of cassava starch industry, has been proposed as a high potential ethanolic fermentation substrate due to its high residual starch level, low ash content and small particle size of the lignocellulosic fibers. As the economic feasibility depends on complete degradation of the polysaccharides to fermentable glucose, the comparative hydrolytic potential of cassava pulp by six commercial enzymes were studied. Raw cassava pulp (12% w/v, particle sizeμm) hydrolyzed by both commercial pectinolytic (1) and amylolytic (2) enzymes cocktail, yielded 70.06% DE. Hydrothermal treatment of cassava pulp enhanced its susceptibility to enzymatic cleavageas compared to …

Alos/Palsar Image Processing Using Dinsar And Log Ratio For Flood Early Detection In Jakarta Based On Land Subsidences, Dodi Sudiana, Mia Rizkinia

Makara Journal of Technology

Flood that occurred in Jakarta is not only influenced by rainfall, urban planning system and drainage alone, but also may be involved land subsidence (LS). LS is possible in because Jakarta stands on top of layers of sediments and the presence of ground water consumption in very large quantities. In this research, the Advanced Land Observing Satellite (ALOS)/Phased Array type L-band Synthetic Aperture Radar (PALSAR) data was processed to determine the level of LS in Jakarta area and its relation to flood potential area. Differential interferometry method (DInSAR) was performed on two PALSAR data with different acquisition years, i.e. 2007 …