Smooth Sheet Research Articles

Electrochemical Corrosion Characteristic of Structured Low Carbon Steel DC04 and Stainless Steel 304 Sheets in Sodium Chloride Solution

In this work structured sheet metals were investigated using electrochemical measurement techniques. The main purpose is obtaining fundamental information about the corrosion resistance of structured sheet metals in comparison to smooth sheet metals as well determination of the influence of the structuring process on the corrosion properties. The corrosion resistance of structured sheet metals is affected by manufacturing process. One of the main influence factors is the change of the surface roughness. In this study the low carbon steel DC04 and the stainless steel 304 (X5CrNi18-10) were investi-gated. The electrochemical tests were carried out in 3%-NaCl solution. Potentiodynamic linear polarization was used to determine such electrochemical characteristics as the free corrosion potential, the corrosion current, the pitting and protection potential. Furthermore, the corrosion rate was calculated for smooth and structured sheet metals of the low carbon steel DC04. For the stainless steel 304 the pitting density was estimated. The surface roughness was measured for both materials. The electrochemical corrosion tests show a small difference in the corrosion behaviour of structured and smooth sheet metals. Structured sheet metals have a lower corrosion resistance than smooth sheet metals. The steel DC04 shows the worst corrosion properties at the structure location “negative” in comparison to the structure location “positive”. The corrosion resistance of the stainless steel 304 is better at the structure location “negative” than at the structure location “positive”. Moreover, the results show the correlation between the surface roughness and the corrosion resistance for structured sheet metals.

A priori Estimates for 3D Incompressible Current-Vortex Sheets

We consider the free boundary problem for current-vortex sheets in ideal incompressible magneto-hydrodynamics. It is known that current-vortex sheets may be at most weakly (neutrally) stable due to the existence of surface waves solutions to the linearized equations. The existence of such waves may yield a loss of derivatives in the energy estimate of the solution with respect to the source terms. However, under a suitable stability condition satisfied at each point of the initial discontinuity and a flatness condition on the initial front, we prove an a priori estimate in Sobolev spaces for smooth solutions with no loss of derivatives. The result of this paper gives some hope for proving the local existence of smooth current-vortex sheets without resorting to a Nash-Moser iteration. Such result would be a rigorous confirmation of the stabilizing effect of the magnetic field on Kelvin-Helmholtz instabilities, which is well known in astrophysics.

Structural and electronic bistability in ZnS single sheets and single-walled nanotubes

We investigate a single sheet graphene analogue and a single-walled nanotube of ZnS using electronic structure calculations. Unlike the nearly perfectly flat structures of graphene and graphene analogues of other binary compounds (e.g., BN, ZnO, SiC), ZnS sheets are predicted to attain higher stability as complex, radically reconstructed structures. This predisposition to reconstruct also persists when ZnS sheets are rolled up into single-walled nanotubes. Smooth nanotubes and flat single sheets of ZnS have significantly smaller band gaps than their reconstructed counterparts, and are found to be metastable minima that are accessible from the reconstructed structures via external strain. This bistable electromechanical coupling may have significant technological potential (e.g., nanosensors, optomechanical switches).

Analytical and Numerical Calculation of the Force and Power Requirements for Air Bending of Structured Sheet Metals

Structured sheet metals with regular bumps offer higher stiffness compared to smooth sheet metals. They can be produced by a hydroforming process. The application of the structured sheet metals, however, is inhibited by the lack of knowledge for the subsequent processing steps. In this paper, the force and power requirements for air bending of structured sheet metals are calculated with a Finite Element Simulation (FE) and an analytical approach. In the first step, the hydroforming manufacturing process of the structured sheet metals is simulated in order to predict the exact geometry and the change in the material properties. Following, air bending simulations have been done taking into account the results of the hydroforming simulation. The FE-Simulations have been carried out with the software package LS-DYNA. The simulation models are validated with the optical displacement measuring system ARGUS and by a series of bending tests. For the analytical calculation the model based on the bending theory is adapted by simplifying the cross section of the structured sheet metals. The results of the FE-Simulation, the analytic calculation and the experiments are compared. The advantages and disadvantages as well as the application areas of the considered methods are indicated.

A Study of Chromium, Cooper, and Lead Distribution from Lignite Fuels Using Cultivated and Non-cultivated Plants as Biological Monitors

Concentrations of chromium, copper, and lead were determined in soil and plant specimens collected from the area of coal power plant (CPP), A. Dimitrios, the largest CPP in Greece located on the eastern part of Ptolemais basin, Macedonia. Two cultivated plants (Brassica oleracea var. capitata L. and Zea mays L.) and two non-cultivated plants (Rumex acetosa L. and Verbascum phlomoides L.) were chosen. The mean heavy metal content in the soil is described in the descending order of Cr>Pb>Cu, while for the plant material, the order was Cr>Cu>Pb. Stations in the vicinity of the CPP showed a distinctly high load of Cr in the soil, whereas for the other metals, no such correlation has been noted. Unexpectedly, high levels of chromium and copper have been found in plant samples of the control station (Grevena) where there is no significant point source of air pollution by particulate matter. In general, roots revealed a higher metal concentration than that of the other plant organs. This is more obvious in B. oleracea var. capitata for all metals studied. Thus, B. oleracea var. capitata possesses the potential for phytoremediation of soils contaminated by metals since this plant is removable together with its roots from the contaminated soil. The most contaminated leaves showed a variation in surface roughness. In V. phlomoides the non-glandular, branched candelabrum-like trichomes on the leaf epidermis effectively trapped and retained a considerable number of particles. In contrast, the waxy cuticle of R. acetosa, which forms a smooth sheet over the epidermal cells, enabled the fast removal of particles by rain or wind. In the case of Z. mays, seeds accumulated the lowest amount of all metals.

More than a century of bathymetric observations and present-day shallow sediment characterization in Belfast Bay, Maine, USA: implications for pockmark field longevity

Mechanisms and timescales responsible for pockmark formation and maintenance remain uncertain, especially in areas lacking extensive thermogenic fluid deposits (e.g., previously glaciated estuaries). This study characterizes seafloor activity in the Belfast Bay, Maine nearshore pockmark field using (1) three swath bathymetry datasets collected between 1999 and 2008, complemented by analyses of shallow box-core samples for radionuclide activity and undrained shear strength, and (2) historical bathymetric data (report and smooth sheets from 1872, 1947, 1948). In addition, because repeat swath bathymetry surveys are an emerging data source, we present a selected literature review of recent studies using such datasets for seafloor change analysis. This study is the first to apply the method to a pockmark field, and characterizes macro-scale (>5 m) evolution of tens of square kilometers of highly irregular seafloor. Presence/absence analysis yielded no change in pockmark frequency or distribution over a 9-year period (1999–2008). In that time pockmarks did not detectably enlarge, truncate, elongate, or combine. Historical data indicate that pockmark chains already existed in the 19th century. Despite the lack of macroscopic changes in the field, near-bed undrained shear-strength values of less than 7 kPa and scattered downcore 137Cs signatures indicate a highly disturbed setting. Integrating these findings with independent geophysical and geochemical observations made in the pockmark field, it can be concluded that (1) large-scale sediment resuspension and dispersion related to pockmark formation and failure do not occur frequently within this field, and (2) pockmarks can persevere in a dynamic estuarine setting that exhibits minimal modern fluid venting. Although pockmarks are conventionally thought to be long-lived features maintained by a combination of fluid venting and minimal sediment accumulation, this suggests that other mechanisms may be equally active in maintaining such irregular seafloor morphology. One such mechanism could be upwelling within pockmarks induced by near-bed currents.

10.2478/s11814-009-0271-y

M/S Hindustan Copper Limited (HCL), India generates large amounts of lean sulfide ores of copper. The current production of lean copper ores in India is 0.55 million tons with ∼0.3% average copper content. Heap-bioleaching of the lean copper ores in 15 and 30 ton scales was undertaken at IMMT, Bhubaneswar. The leaching study showed 0.09% dissolution of copper from the ore body per day. The leach liquor was processed through solvent extraction and electrowinning. Extraction of copper from the actual leach liquor was carried out with 1.5% LIX 622N in kerosene with zero co-extraction of iron. The copper-free raffinate was fed back to the leaching unit. Stripping of copper from the loaded organic was carried out with 180 kg/m3 H2SO4. The copper pregnant electrolyte was passed through a carbon column to make it free from entrained organic and was fed to the electrowinning unit. The increase in current efficiency was due to the increase in the concentration of electrolyte. The energy consumption was 1.7 kWh/kg at a flow rate of 4.5 L/h. Smooth and bright sheets of copper of 99.99% purity were obtained.

Processing Behaviour of High-cis Polybutadiene in Rubber Compounds

Compounding and extrusion are critical steps in the production of rubber compounds of a reliable quality within a given timeframe and hence at a reasonable cost. The materials used - including the rubber types -are varied in order to obtain improvements in product performance. One of the most important of the synthetic rubbers is neodymium polybutadiene (NdBR) which, because of its exceptional microstructure and macrostructure, offers outstanding properties. Through the use of high-cis NdBR, marked improvements have been obtained in end products in terms of dynamic performance and good fatigue and wear characteristics. At the same time, however, the processing behaviour of this type of rubber requires adjustments to be made at the compounding and extrusion stage. This can lead to problems in the handling of the milled sheet and profiles, resulting for example in severe surface roughness or die swell. In extreme cases the benefits of NdBR can be masked altogether if no adjustments are made to the processing stages. This paper presents countermeasures to improve the processability of NdBR by adapting the compounding and extrusion conditions to its specific requirements. The ratio of viscosity and elasticity is specific to each type of rubber and therefore requires individual adjustment of the processing conditions. We show that under appropriately adjusted conditions, even using NdBR grades with the highest molecular weights (e.g. Buna CB22), short compounding times and smooth milled sheets and extrusion profiles with a glossy surface can be obtained. Under these conditions neodymium polybutadiene rubbers provide a basis for an ideal combination of excellent material properties and improved processing behaviour. The positive characteristics of NdBR are retained when it is used in blended rubbers such as an SSBR/BR blend. The rules regarding the optimisation of process conditions for pure NdBR systems apply here too.

Instability of Confined Water Films between Elastic Surfaces

We investigated the dynamics of nanometer thin water films at controlled ambient humidity adsorbed onto two atomically smooth mica sheets upon rapidly bringing the surfaces into contact. Using a surface forces apparatus (SFA) in imaging mode, we found that the water films break up into a distribution of drops with a typical thickness of a few nanometers and a characteristic lateral size and spacing of several micrometers. Whereas the characteristic length is found to be independent of the ambient humidity, the characteristic time of the breakup decreases from approximately 1 to 0.01 s with increasing humidity. The existence of characteristic length and time scales shows that this breakup is controlled by an instability rather than a conventional nucleation and growth mechanism for SFA experiments. These findings cannot be explained by a dispersion-driven instability mechanism. In contrast, a model involving the elastic energies for the deformation of both the mica sheets and the underlying glue layer correctly reproduces the scaling of the characteristic length and time with humidity.

Asymptotic modelling of conductive thin sheets

We derive and analyse models which reduce conducting sheets of a small thickness ε in two dimensions to an interface and approximate their shielding behaviour by conditions on this interface. For this we consider a model problem with a conductivity scaled reciprocal to the thickness ε, which leads to a nontrivial limit solution for ε → 0. The functions of the expansion are defined hierarchically, i.e. order by order. Our analysis shows that for smooth sheets the models are well defined for any order and have optimal convergence meaning that the H 1-modelling error for an expansion with N terms is bounded by O(ε N+1) in the exterior of the sheet and by O(ε N+1/2) in its interior. We explicitly specify the models of order zero, one and two. Numerical experiments for sheets with varying curvature validate the theoretical results.

Recovery of copper values from bio-heap leaching of low grade Malanjkhand chalcopyrite ore

M/S Hindustan Copper Limited (HCL), India generates large amounts of lean sulfide ores of copper. The current production of lean copper ores in India is 0.55 million tons with ∼0.3% average copper content. Heap-bioleaching of the lean copper ores in 15 and 30 ton scales was undertaken at IMMT, Bhubaneswar. The leaching study showed 0.09% dissolution of copper from the ore body per day. The leach liquor was processed through solvent extraction and electrowinning. Extraction of copper from the actual leach liquor was carried out with 1.5% LIX 622N in kerosene with zero co-extraction of iron. The copper-free raffinate was fed back to the leaching unit. Stripping of copper from the loaded organic was carried out with 180 kg/m3 H2SO4. The copper pregnant electrolyte was passed through a carbon column to make it free from entrained organic and was fed to the electrowinning unit. The increase in current efficiency was due to the increase in the concentration of electrolyte. The energy consumption was 1.7 kWh/kg at a flow rate of 4.5 L/h. Smooth and bright sheets of copper of 99.99% purity were obtained.

Basic forensic identification of artificial leather for hit-and-run cases

Single fibers retrieved from a victim's garments and adhered to the suspect's automobile have frequently been used to prove the relationship between victim and suspect's automobile. Identification method for single fiber discrimination has already been conducted. But, a case was encountered requiring discrimination of artificial leather fragments retrieved from the victim's bag and fused fibers from the bumper of the suspect's automobile. In this report, basic studies were conducted on identification of artificial leathers and single fibers from leather materials. Fiber morphology was observed using scanning electron microscopy (SEM), color of these leather sheets was evaluated by microspectrophotometry (MSP), the leather components were measured by infrared micro spectrometry (micro-FT-IR) and the inorganic contents were ascertained by micro-X-ray fluorescence spectrometry (micro-XRF). These two methods contribute to other analytical methods too, in the case of utilized single fiber analytical methods. The combination of these techniques showed high potential of discrimination ability in forensic examinations of these artificial leather samples. In regard with smooth surface artificial leather sheet samples, a total of 182 sheets were obtained, including 177 colored sheets directly from 10 of 24 manufacturers in Japan, and five of them were purchased at retail circulation products. Nine samples of suede-like artificial leather were obtained, 6 of them were supplied from 2 manufacturers and 3 sheets were purchased as retailing product. Single fibers from the smooth surface artificial leather sheets showed characteristic for surface markings, and XRF could effectively discriminate between these sheets. The combination of results of micro-FT-IR, color evaluation by MSP and the contained inorganic elements by XRF enabled to discriminate about 92% of 15,576 pairs comparison. Five smooth surface samples form retailing products were discriminated by their chemical composition into four categories, and in addition color information to this result, they were clearly distinguished. Suede-like artificial leather sheets showed characteristic extra-fine fibers on their surface by the observation of SEM imaging, providing high discriminating ability, in regard with suede-like artificial leather sheets were divided into three categories by micro-FT-IR, and the combination of these results and color evaluation information, it was possible to discriminate all the nine suede-like artificial leather sheets examined.

Dispersion of Graphene Sheets in Organic Solvent Supported by Ionic Interactions

Organic solution-processable graphene sheets were prepared using a large-scale novel approach based on a transfer process assisted by ionic interactions. Smooth monolayer graphene sheets were easily fabricated on a substrate from organic solution. Such a noncovalent functionalization preserves the extended aromatic conjugation of reduced graphene sheets, giving rise to high-conductivity cast films.

Biomagnetic field detection using very high sensitivity magnetoimpedance sensors for medical applications

AbstractThis paper demonstrates the performance of magnetoimpedance (MI) sensors for biomagnetic field recording. The rms noise of an amorphous wire MI sensor with 600 turns of pick‐up coil was estimated as approximately 3 pT/Hz1/2 at 1 Hz. Here, we demonstrate that this sensitivity is enough to clearly detect magnetic cardiogram signals. We also measured the biomagnetic field around a smooth muscle tissue sample taken from a guinea‐pig. We discovered that the magnetic‐field waveform of a small tissue sample is similar to the voltage waveform measured by a microelectrode array in a smooth muscle sheet sample. The results suggest that the localized biomagnetic field generated by smooth muscle cells can be detected by an MI sensor. We concluded that the MI sensor is a promising device for use as a noninvasive tool to test cell activity or function through magnetic‐field measurement. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

One-step electrodeposition synthesis and electrochemical properties of Cu6Sn5 alloy anodes for lithium-ion batteries

Cu6Sn5 alloys were successfully electrodeposited on rough Cu foils and smooth Cu sheets using a facile one-step electrodepositing method, and their structural and electrochemical properties were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), galvanostatic charging/discharging testing and electrochemical impedance spectroscopy (EIS). The influence of surface morphology of the current collectors on the cycleability and the interfacial performance of the Cu6Sn5 alloy electrode are both discussed. The results demonstrate that the Cu6Sn5 alloy electrode on the rough Cu foil presented better electrochemical performance than that on the smooth Cu sheet because its rough surface could buffer the volume changes to some extent. The first discharging (lithiation) and charging (delithiation) capacities were measured at 462 and 405 mAh g−1 respectively with high initial coulomb efficiency of 88%, with charging capacity in the 50th cycle remaining 76% of that in the first cycle. The phase transformation during initial lithiation was detected by electrochemical impedance spectroscopy (EIS) and its trend versus electrode potential is also discussed.

FMF-06 CONTACT CHARACTERISTICS OF A RUBBER ROLLER AND A FLEXIBLE MEDIUM(Flexible Media Feeding and Handling Machines II,Technical Program of Oral Presentations)

A method for of numerically calculating the asperity contact mechanics between a rubber roller and a smooth sheet was developed by considering the van der Waals force at the contacting asperities. As the rms asperity height decreased, adhesion and a jump-in contact phenomenon were observed. When the friction force was assumed to be proportional to either the total contact area or the real contact force, the obtained friction coefficient was decreased with an increase in the applied load.

Influence of the Physical Properties of a Liquid on Perforations in a Radial Liquid Sheet Jet

Perforations caused by the laminar-turbulent transition of a radial liquid sheet are described. A liquid film discharged from a small gap between a disk and a nozzle flows radially outward on the disk and forms a radial liquid sheet beyond the disk edge. The radial liquid sheet is unstable because of the internal velocity profile with an inflexion point. The instability causes a laminar-turbulent transition just beyond the disk edge and the transition leads to strong turbulence. Flow patterns depend completely on the frequency of perforations produced by this turbulence; that is, a large number of perforations leads to atomization of the liquid sheet, whereas no perforations results in a smooth liquid sheet. In this paper, we clarified the dependence of perforation on the physical properties of test liquids.

Lithiation/delithiation performance of Sn–Co alloy anode using rough Cu foil as current collector

Sn–Co alloys were electrodeposited on the rough Cu foil and smooth Cu sheet, respectively. The capacity retention of the Sn–Co alloy electrode electrodeposited on the rough Cu foil in the 70th cycle was found to be 80.0% compared with the maximal capacity, which was much better than that of the Sn–Co alloy electrode on the smooth Cu sheet. The revolution of the surface morphology of the Sn–Co alloy electrode during cycling was investigated by scanning electron microscopy. The result indicated that the reversibility of the expansion and contraction of the Sn–Co alloy electrode on the rough Cu foil during charging/discharging assisted by the unique rough surface was one main reason of improving the cycleability. Solid electrolyte interphase (SEI) film was detected on the Sn–Co alloy electrode surface by electrochemical impedance spectroscopy (EIS) during lithiation/delithiation, and the result demonstrated that the SEI film suffered breaking and repairing at different lithiation status. In addition, the unique phase transformation process for the Sn–Co alloy electrode during first lithiation was also investigated by EIS.

Sn–Co alloy anode using porous Cu as current collector for lithium ion battery

Porous Cu was prepared by electrodepositing Cu on a Cu foil using hydrogen bubbles as dynamic template, followed annealing at appropriate conditions to strengthen the adhesion between the porous Cu layer and the Cu foil substrate. Sn–Co alloy was then electrodeposited on the porous Cu substrate which served as current collector to be used as anode of lithium ion battery. X-ray diffraction (XRD) and EDS analysis indicated that the Sn–Co alloy was an intermetallic compound of CoSn 3, whose surface structure is stable as illustrated by scanning electronic microscopy (SEM) images obtained before and after electrochemical cycles. It has also revealed that the Sn–Co alloy anode on the porous Cu substrate possessed a relative large capacity and a superior cycleability than that of the Sn–Co alloy anode on the smooth Cu sheet. The first discharge and charge capacities were measured respectively at 726 and 563 mAh g −1, and its capacity in the 50th cycle was retained at ca. 71% of that in the second cycle, which has been improved more than 3 times higher of that of the Sn–Co alloy anode on the smooth Cu sheet under the same conditions.

Pemeriksaan Mutu Malam Model yang Beredar di Yogyakarta

Modelling wax is an auxiliary material in acrylic denture fabrication. This material should have standard quality. Many local and imported brand of modelling waxes are distributed in Yogyakarta. The aim of this study is to examine the quality of modelling waxes in Yogyakarta. The aim of this study is to examine the quality of modelling waxes in Yogyakarta based on international standard. Seven brand of modelling waxes (Rusco tropical, Cavec Tropical, Ruby, SMIC, Anchor Brand medium, Anchor Brand Hard, and Anchor Brand Medium) were exained by ISO 12163 (ANSI/ADA no. 24) specification. The specification which were examined were general requirements (uniform shapes, free from foreign materials, smooth sheets, uniform texture, cohere if softened, and uniform dimension), special requirements (color, odor & flavour, softening, trimming and flaming), and preparation for delivery requirements (packaging and marking). The modelling waxes were stated fulfill the requirements if all 5 samples of each brands were suitable with the specification. The results showed that one brand (Cavec Tropical) fulfilled general and specific requirements, 1 brand (SMIC) only fulfilled general requirements and 3 brands (Rusco tropical, Ruby and Anchor Brand Hard) only fulfilled special requirements. No brand fulfilled preparation for delivery requirements. The conclusion of this study was no brand of modelling waxeds distributed in Yogyakarta fulfilled all requirements.