Iron Sheet Research Articles

Optical microscopic analysis of constrained groove pressed followed by cold rolled ARMCO iron sheet material

ABSTRACT This paper is entitled to investigate microstructure of ARMCO Fe after constrained groove pressing and further after merging of both constrained groove pressing and cold rolling processes. Optical microscopic studies revealed increased number of equiaxed grains as a function of constrained groove pressing cycles. Such grain morphology was later transformed into a complete elongated grain structure due to plain strain compression during different percentage cold rolling reductions. Cold rolling not only increased strain progressively in the constrained groove pressed samples, but also had a pronounced influence in bringing in ultrafine grained structures (less than ~1 µm) in the material.

Building a Community Library

This paper chronicles interventions to renovate and repurpose a community library in one of the poorest countries in the world; Malawi, where over 80% of the population lives below the poverty line (less than US$1.25/day). This initial report is based on activities undertaken by a team of individuals with diverse expertise and cultural backgrounds, and a common vision for repurposing the Kwakupokela Community Library. To date, key achievements include: the Kwakupokela Educational Trust has been created and registered with the Malawi government as a non-governmental organization which now operates the library; a Memorandum of Understanding (MoU) has been signed with Mzuzu University; new books have been donated; and both new and old library books have been processed; the dilapidated and relentlessly leaking roof has been replaced with new iron sheets; the ceiling has been fixed; and the inner walls painted. More importantly, the library has opened its doors to the community. Challenges remain for this ongoing initiative, and include outdated and limited information resources, sustainability of library operations, space shortages and hygiene issues, including lack of restrooms. Strategies have been developed to deal with the mentioned challenges, though their implementation will depend on availability of resources. This paper describes the role librarians can play in uplifting the living conditions of people in rural areas by taking relevant information resources to these segregated, neglected and dejected communities.

Investigation on Spring-Back Effect of Galvanized Iron Sheet

Sheet metal bending is a useful process utilized in varying applications. Investigations in sheet bending find its importance as it is subjected to spring-back upon withdrawal of load and it differs based on material property and its size, etc. Therefore, maintaining specification of a bent object requires appropriate strategy to adopt. In this work, influence of thickness of galvanised iron sheet metal, punch radius and die corner radius on spring-back is considered. Three different values are taken for punch radius, die corner radius and thickness. Experiments are designed according to response surface methodology (RSM) and analysed by ANOVA technique. From various contour plots and surface plots, it is observed that sheet thickness has significant effect on springback. Influence of other two parameters is comparatively less if considered individually, but the combined effect is quite significant.

Mold Flow Analysis of Motor Core Gluing with Viscous Flow Channels and Dipping Module.

A motor core is formed by stacking iron sheets on top of each other. Traditionally, there are two stacking methods, riveting and welding, but these two methods will increase iron loss and reduce usage efficiency. The use of resin is the current developmental trend in the technology used to join iron sheets, which has advantages including lowering iron loss, smoothing magnetic circuits, and generating higher rigidity. The flow behavior of resin in gluing technology is very important because it affects the dipping of iron sheets and the stacking of iron sheets with resin. In this study, a set of analytical processes is proposed to predict the flow behavior of resin through the use of computer-aided engineering (CAE) tools. The research results are compared with the experimental results to verify the accuracy of the CAE tools in predicting resin flow. CAE tools can be used to predict results, modify modules for possible defects, and reduce the time and costs associated with experiments. The obtained simulation results showed that the filling trend was the same as that for the experimental results, where the error between the simulation results for the final dipping process and the target value was 0.6%. In addition, the position of air traps is also simulated in the dipping process.

Novel, simple, and environmentally safe method for wastewater pollutant removal

In this work, a new methodology has been developed for the elimination of cobalt, nickel and a mixture of both metals from synthetic wastewater in a continuous way. This methodology consists of the electrochemical formation of ferrites of these metals through the oxidation of iron sheets and the reduction of water. Two critical process parameters, current densities and initial pollutant concentration, were analysed. An initial batch prototype resulted in efficiencies on the order of 98% under conditions of applied densities of 50 mA/cm2 and concentrations of both metals of until 100 ppm of the ions. The obtained particles have been characterized by X-ray diffraction to determine the formation of ferrites without the appearance of secondary phases. The formed particle sizes are approximately 30 nm, with hemispherical or flower-like shapes. A flow system prototype was designed for the recirculation of the solution with 100 ppm of both contaminating metals, obtaining approximately 90% recovery with an easy magnetic harvesting.

An Equilibrated Error Estimator for the Multiscale Finite Element Method of a 2-D Eddy Current Problem

The multiscale finite element method (MSFEM) is a valuable tool to solve the eddy current problem in laminated materials consisting of many iron sheets, which would be prohibitively expensive to resolve in a finite element mesh. It allows using a coarse mesh that does not resolve each sheet and constructs the local fields using predefined micro-shape functions. This article presents for the first time an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a posteriori</i> error estimator for the MSFEM, which considers the error with respect to the exact solution. It is based on flux equilibration and a modification of the theorem of Prager and Synge and provides an upper bound for the error that does not include generic constants. Numerical examples show a good performance in both linear and nonlinear cases.

Comparison of the efficiency of solar-powered prototype vapour compression cooler with evaporative charcoal cooler in maintaining quality of French beans

The quality and shelf life of French beans is affected by the time of harvesting and storage period. Cooling immediately after harvesting is important. The use of a solar evaporative cooling system is suitable for use in rural areas with no power grid connections. This study compared evaporative charcoal cooler and solar cooling systems on improving the quality and shelf life of French beans. The prototype was made using mathematical modeling equations and was powered by solar power while the evaporative charcoal cooler was made from iron sheets with charcoal walls. Freshly harvested French beans were stored under the two cooling systems. The weight and temperature of the stored produce were checked hourly. At the end of the day, produce was packed into modified atmosphere packaging (MAP) bags and stored for 7 days in a cold room. After seven days, oxygen and carbon dioxide levels were measured using a Bridge gas analyzer. The results show significant differences in weight loss between produce stored in evaporative charcoal shed and solar cooler prototype with those stored in evaporative charcoal cooler having 5% weight reduction while those solar coolers having 3% weight loss. A higher accumulation of CO2 was realized in the evaporative charcoal cooler than in the solar-powered cooler. The solar-powered cooler maintained weight, reduced the temperature of products, and maintained the balance between carbon dioxide and oxygen thus reduction in metabolic activities. This enhanced the shelf life and quality of the produce.

Transparent and Flexible Amphiphobic Coatings with Excellent Fold Resistance via Solvent-Free Coating and Photocuring of Fluorinated Liquid Nitrile-Butadiene Rubber.

Amphiphobic surfaces have been developed for various applications. However, the harsh construction conditions and multistep processes limit their practical application. Especially for those with a particular surface roughness and morphology, the amphiphobic property might provide a slight deformation. Here, a facile large-area construction of transparent and flexible amphiphobic coatings with excellent fold resistance has been established by simple casting of the fluorinated liquid nitrile-butadiene rubber (F-LNBR) followed by solvent-free photocuring. It was found that the fluorocarbon groups could concentrate onto the coating surface during the UV-induced photocuring. With a certain coating amount, a stable oleophobic coating was achieved with static contact angles of about 95° and 111° for nonpolar oil (n-hexadecane) and polar oil (diiodomethane). Most importantly, the static contact angles of water and diiodomethane of the amphiphobic coatings on the iron sheet increased after bending and remained around 131° and 120° after being completely folded in half for 100 cycles because the inner fluorocarbon groups could be squeezed out from the flexible cross-linked rubber matrix as a reservoir. Such features indicated the promising self-cleaning and surface protection of the proposed transparent and flexible amphiphobic coatings for deformable substrates.

Høj Stene – en monumental skibssætning ved Gudenåen

Høj Stene – en monumental skibssætning ved Gudenåen

Preparation and properties of catechol-based waterborne polyurethane based on thiol-ene click chemistry reaction

A highly effective way is found to incorporate dopamine (DA) containing catechol groups into waterborne polyurethane backbone. Firstly, prepolymer polyurethane (PPU) containing sulfydryl were created through stepwise polymerization in which isophorone diisocyanate (IPDI) was as hard segment, polyethylene glycol (PEG)(Mn=600) was as soft segment, dimethylolpropionic acid (DMPA) was as hydrophilic monomer and monothioglycerol (MON) was as chain extender. Then a series of catechol-based waterborne polyurethanes (MON-PPU-DOMA) was obtained by introducing methacrylamide dopamine (DOMA) into polyurethane backbone via thiol-ene click chemistry. FT-IR, 1H-NMR and UV–vis spectra showed that DOMA was successfully incorporated into polyurethane backbone. TG and mechanical properties testing results indicated that the heat resistance and tensile strength of MON-PPU-DOMA films were obviously improved. Moreover, MON-PPU-DOMA/Fe3+ complex was obtained by MON-PPU-DOMA with Fe3+ triggered via adjusting pH and their color and state change was apparent, which also made it possible for MON-PPU-DOMA/Fe3+ to become an injection adhesion material. MON-PPU-DOMA was used to bonding different substrates. The results showed that the lap shear strength of MON-PPU-DOMA to iron sheet was 3.23 MPa, which was obviously bigger than that of MON-PPU without DOMA. The introduction of DOMA can significantly improve adhesive ability of polyurethane. Because it is difficult to dissolve in DMF, MON-PPU-DOMA emulsion has the potential of being an environmentally friendly coating on the surface of iron substrates.

High affinity lanthanum doped iron oxide nanosheets for phosphate removal

• New synthesis route leading to nano La(OH) 3 cluster interlayered iron oxides. • Sorbent affinity for phosphate increases with La content with partitioning coefficients up to 10 5 L/kg. • La doped sorbents show high selectivity for phosphate in presence of competing solutes. • Sorption of phosphate dominated by inner sphere La-O-P complexation. Phosphorus induced eutrophication of freshwaters is one of the great global challenges. As the critical threshold concentration for eutrophication is very low, there is a strong need for development of phosphate sorbents with high affinity and selectivity. Single sheet iron oxide (SSI), a nanomaterial prepared from oxidation and exfoliation of layered iron(II)-iron(III) hydroxide (green rust), is a fast reacting and promising sorbent. Phosphate sorption affinity and selectivity may be improved by incorporation of lanthanum (La) in the structure. Lanthanum was added during SSI synthesis resulting in La-SSIs with 0 to 22.5 wt% of La content. XPS and EXAFS showed all La was present as La(OH) 3 nanoclusters between iron hydroxide layers and on the surface of SSI. The sorbent showed fast phosphate sorption with 90% completion within 30 min and high stability with minimal La leaching. All La-SSI nanomaterials showed better sorption affinity than non-doped SSI, and the La-SSI with the highest La content showed an extreme affinity with K d of 10 5 L/kg at solution concentration of 0.1 mg P/L. The sorption affinity was not seriously affected by pH. The La-SSIs showed high selectivity for phosphate with<10% reduction in phosphate sorption in presence of co-existing solutes (Cl – , NO 3 – , SO 4 2- , HCO 3 – and humic acid). Similar high affinity and selectivity was seen for phosphate sorption in real natural waters. The main phosphate sorption mechanism is attributed to inner sphere Fe-O-P and La-O-P surface complexation. In conclusion La doping turns SSI into a high-affinity and selectivity sorbent that has potential for polishing low-phosphate yet eutrophying natural waters such as drainage and lake waters.

Effects of Ammonium Thiocyanate and pH of Aqueous Solutions on Hydrogen Absorption into Iron under Cathodic Polarization

To evaluate the susceptibility of steels to hydrogen embrittlement, it must be hydrogen charged and have its hydrogen content controlled before any mechanical testing. In this study, hydrogen permeation tests of an iron sheet were performed during potentiostatic hydrogen charging in various solutions containing ammonium thiocyanate to obtain a guideline for efficient hydrogen charging for a wide range of hydrogen contents. As the polarization potential shifted in the negative direction, the hydrogen permeation current increased before becoming almost constant. In all cases, besides when an aqueous sodium hydroxide solution was employed, the hydrogen permeation current increased due to the addition of ammonium thiocyanate. The effect of adding ammonium thiocyanate was enhanced as the aqueous solution pH was decreased. The hydrogen permeation current under various hydrogen charging conditions obtained in this study can be used as a reference for hydrogen charging of steels.

Magnetic Resistance of HTS Maglev Moving Above a Permanent Magnet Guideway with Large Magnetic Field Fluctuations

Unlike the magnetic levitation characteristics that most research focuses on, this article focuses on the magnetic resistance of high-temperature superconductor (HTS) maglev system. By superimposing iron sheets on the permanent magnet (PM) track to create significant magnetic field fluctuations, we studied the magnetic resistance of HTS-PM maglev caused by the fluctuating magnetic field, and used the rotating orbit platform to study the influence of the running speed and the field cooling height (FCH) on the magnetic resistance. The magnetic resistance is found mainly originating from the self-stabilizing characteristic of type II superconductor in an uneven external magnetic field, showing oscillation characteristics near a certain equilibrium value, with nearly constant amplitude at a given FCH and running speed. Spectrum analysis shows that the main frequency of the oscillation is the same as the frequency of the alternating magnetic field received by the maglev vehicle during running above the fluctuating magnetic field, revealing that this is a forced vibration driven by a fluctuating magnetic field. The oscillation amplitude and power density increase steadily with the increase of FCH, and show the characteristics of first increasing and then reaching saturation with the increase of running speed. The research results reveal that there is an inherent correlation between the oscillation of the magnetic resistance and the stability of the system.

Laser Welding of Grey Cast Iron with Spheroidal Graphite-Influence of Process Parameters on Crack Formation and Hardness

In the investigation at hand, sheets of ferritic and pearlitic grey cast iron with spheroidal graphite are welded using a fiber-laser. The influence of varying laser power and welding speed on the macroscopic characteristics of the weld seam and crack formation are analyzed and discussed. Substantial crack formation with crack densities of up to 2.93 cm−1 are found. Furthermore, hardness measurements are conducted to evaluate the formation of brittle phases within the weld metal and heat-affected zone. Peak hardness values of up to 860 HV0.3 and 975 HV0.3 are identified in EN-GJS-400-15 and EN-GJS-700-2, respectively. Subsequently, a proposition on the dependence of crack formation on weld seam width is given. Furthermore, the influence of nickel-containing filler material on the microstructure, crack formation and hardness is studied. It can be derived from the results that laser-beam welding of grey cast iron with spheroidal graphite requires further research in order to achieve crack-free weld seams and hinder the formation of undesirable, brittle phases.

Electrosynthesis of Co, Ni and Zn ferrites nanoparticles in the presence of external magnetic field

Magnetic complex oxides of iron nanoparticles are among the most important materials that have been studied. They have been widely used in different areas such as electronic devices, information storage, biomedical areas, drug-delivery, catalyst, and wastewater treatment. In different applications of nanoparticles, the shape and size of particles are very important because the electrical, optical, and magnetic properties of the nanoparticles depend on their dimension. In this study, nanoparticles of cobalt, nickel, and zinc ferrites were synthesized in uniform size by an electrochemical technique. First, the anode was made electrochemically by depositing each metal of zinc, nickel, and cobalt on the iron sheet from the solutions of 0.1 M Co2+, Ni2+, and Zn2+ ions as the precursor. Then the electrosynthesis of ferrite nanoparticles was performed in a second electrochemical cell where the prepared electrode was anode and stainless steel (316L) was cathode in the electrolyte solution of CTAB 0.04 M. The optimized value of current density was applied to the electrochemical cell. After then the same synthesis was carried out in the magnetic field supplied by two magnets. The prepared nanoparticles were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The magnetic properties were investigated by vibrating sample magnetometer (VSM). The comparison of two samples prepared in the magnetic field and without it showed the average size of the samples synthesized in the magnetic field was in the narrower size distribution of 20–30 nm and the saturation magnetization of the nanoparticles increased in the magnetic field.

A Hierarchical Error Estimator for the MSFEM for the Eddy Current Problem in 3-D

The aim of this article is to develop an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a posteriori</i> hierarchical error estimator for the multiscale finite element method (MSFEM). The MSFEM is used to solve the linear eddy current problem in a stack of iron sheets. It allows for a calculation of the solution without having to resolve each sheet in the finite element mesh. A hierarchical local error estimator for nodal elements and edge elements is adapted to the multiscale setting. The estimator allows for adaptive p-refinement on the coarse multiscale mesh. Numerical examples show an increased order of convergence compared to uniform refinement. The proposed error estimator increases the efficiency of the MSFEM, requiring even fewer degrees of freedom. It is the first error estimator presented for the 3-D MSFEM for the eddy current problem.

Preparation of Polycrystalline‐Mixed Graphene Film with Benzene Solution by Electromagnetic Induction for Application in Metal Corrosion Protection

AbstractMetals used in the electronics, machinery manufacturing, and construction industry are often chemically reactive and corrosion‐prone, while barriers on a metal as a conventional method for anticorrosion always have negative effects including a toxic nature, thickness increase over time, and changes of electrical and optical properties after surface coating. This study employs a benzene solution to induce a rapid formation of a polycrystalline graphene film on copper foils or iron sheet substrates under atmospheric conditions by electromagnetic induction, which is non‐toxic and environment‐friendly and produces favorable anticorrosive effects. The microscopic analysis shows that the as‐grown film is a polycrystalline graphene complex of graphene crystallites. It is revealed that the copper foils or iron sheets with the graphene film is significantly resistant to strong corrosion, with the corrosion current density is one order of magnitude lower when compared with samples without the graphene films. The polycrystalline structure of the graphene film can prevent the electronic conduction of the surface, thereby reducing corrosion and local over‐corrosion phenomena when metals are situated in a long‐term exposure to corrosive environments.

Household-Level Effects of Energy Insecurity on Welfare in Southern Africa: A Malawian Case Study

The debate of energy security has, over the past decades, centered on supply factors within the energy policy framework in the public policy discourse. Much more empirical evidence is required to fully understand the household-level effects of energy security on development outcomes. This paper explores the characteristics of the households that face energy insecurity and also analyze the effects of energy insecurity on household welfare using the recent data from the Malawi Fourth Integrated Household Survey(IHS4) 2016-2017. Overall, 42.58% of Malawian households were found to be energy insecure and the study findings show that the energy insecure were a heterogenous group compared to the energy secure. The heterogeneity exist because of differences in demographics (likely to be advanced in age, likely to be females, less likely to have a household head with formal education); socioeconomic status (likely to be poor, had low wealth levels); geography (likely to be rural dwellers in the central and southern parts of Malawi); housing and dwelling status (less likely to be renters, less likely to be found in permanent or semi-permanent buildings that have iron sheets and cement floor). Additional results from econometric analysis showed that energy insecure households reduced their food consumption by 2.3% for each 1% unit increase in the share of the energy costs in their total household budget. Similarly, on the education outcome, the energy insecure households reduced their education expenditure by 3.6% for each 1% unit increase in the share of the energy costs over the total household expenditure. These findings show that energy security plays a key role towards improvement of household welfare in general as this might have short term and long-term negative implications on human capital development.

Structure Design and Flow Field Analysis of a Model Test Box Used to Study Freezing Temperature Field of Seepage Stratum

To meet the research needs of the freezing temperature field under seepage, we investigate and design a seepage‐freezing model test box, which can meet the requirements of strength, deformation, dispersed flow, simulated laminar flow, and water sealing performance. Using theoretical analysis and calculation, the pressure design index of the model box was obtained. Based on safety considerations, the model test box was designed with a pressure vessel bearing of 0.05 MPa. The structure of “sink + porous plate” was used inside the box. By flow field analysis, the porous plate can effectively reduce the influence of flow convergence to the orifice on the flow field and achieve the purpose of dispersed‐water flow and laminar flow simulation. The composite structure form of “panel + frame beam” was adopted to perform the load‐bearing test. Under the pressure of 0.05 MPa, the maximum deformation in the x, y, and z directions was &lt;2.4 mm, and the maximum stress was approximately 248 MPa. The model box could meet the requirements of strength and deformation. Water sealing between the upper cover plate and lower box body was achieved by arranging bolts, iron sheets, and silica gel strips. After testing the processed box, we found that the designed box can fully meet the test requirements. These research results may be used as a reference for the development and design of other seepage‐freezing model test boxes.

Grain refinement of the surface layer of an iron sheet by the burnishing method

Grain refinement of the surface layer of an iron sheet by the burnishing method