Kinetics of hydrogen evolution on a stainless steel electrode

The kinetic parameters for the hydrogen evolution reaction on a stainless steel substrate have been obtained from a study of the steady-state polarization curves as well as the galvanostatic transients. The high Tafel slope obtained in the steady-state polarization measurements was ascribed to the presence of an oxide film present on the surface of the stainless steel electrode.

Tax transparency can work for companies if they do it right

The Tax Transparency Package released by the European Commission last week comes amid global moves by the G20 and others to make it more difficult for companies to avoid paying their fair share of tax. But as serious information sharing plans are hammered out between nations around the world, the Australian government is considering protecting the privacy of some of Australia’s richest people, diluting transparency measures aimed at private companies.

Conserving Biodiversity as If People Matter: A Case Study from India

India has rich traditions of nature conservation as well as a vigorous official program of protection of nature reserves developed over the last 40 years. However, the officialp rograms uffers fromt otal relianceo n authoritarianm anagement arrangements in which decisions are made centrally and coercion is used to implement them. At the same time, the state apparatus organises subsidized resource flows to the urbanindustrial- intensivea griculturalc omplex which promote inefficient,n on-sustainable resource-use patterns that are inimical to conservation of biodiversity. These processes are illustrated within the concrete setting of the district of Uttara Kannada in southern India. It is suggested that the interests of conservation would be served far better by an approach that withdraws the subsidies to the elite so that a much more efficient, sustainable and equitable pattern of resource use, compatible with conservation of biodiversity, can be instituted. In conjunction with this, the larger society should involve local people in working out detailed plans for conservation of biodiversity and offer them adequate authority as well as appropriate financial incentives to implement these plans. The paper goes on to illustrate how such an approach may be implemented in the case of Uttara Kannada.

Electrochemical reduction of hydrogen peroxide on stainless steel

Electrochemical reduction of hydrogen peroxide is studied on a sand-blasted stainless steel (SSS)electrode in an aqueous solution of NaClO4.The cyclic voltammetric reduction of H2O2 at low concentrations is characterized by a cathodic peak at -0 center dot 40 V versus standard calomel electrode(SCE).Cyclic voltammetry is studied by varying the concentration of H2O2 in the range from 0 center dot 2 mM to 20 mM and the sweep rate in the range from 2 to 100 mV s(-1)Voltammograms at concentrations of H2O2 higher than 2 mM or at high sweep rates consist of an additional current peak, which may be due to the reduction of adsorbed species formed during the reduction of H2O2. Amperometric determination of H2O2 at -0 center dot 50 V vs SCEprovides the detection limit of 5 A mu M H2O2. A plot of current density versus concentration has two segments suggesting a change in the mechanism of H2O2 reduction at concentrations of H2O2 a parts per thousand yen 2 mM. From the rotating disc electrode study, diffusion co-efficient of H2O2 and rate constant for reduction of H2O2 are evaluated.

Microtribology and Friction-Induced Material Transfer in Layered MoS2 Nanoparticles Sprayed on a Steel Surface

Frictional performance of molybdenum disulfide (MoS2) particles sprayed on a substrate is investigated in a ball-on-disc tribometer. The ability of large (similar to 2 mu m) and small (similar to 50 nm) particles to generate low-friction transfer film is investigated with a view to elucidate the requirement for film formation. Particle migration, particle stability in the contact region, oxidation potential, and particle adhesion to the substrate are explored within a span of operating parametersp; normal load, and sliding velocity. It is found that the larger particles are able to migrate to the contact to raise a homogeneous but nonuniform low-friction transfer film that flows plastically to yield large contact areas, which aid in wear protection. Within the present load and speed range, the inability of small particles to stay in the contact region and undergo basal slip militates against the formation of a low-friction transfer film.

Tribological properties of γ-Y2Si2O7 ceramic against AISI 52100 steel and Si3N4 ceramic counterparts

Reciprocating ball-on-flat dry sliding friction and wear experiments have been conducted on singlephase γ-Y2Si2O7 ceramic flats in contact with AISI 52100 bearing steel and Si3N4 ceramic balls at 5-15N normal loads in an ambient environment. The kinetic friction coefficients of γ-Y2Si2O7 varied in the range over 0.53-0.63 against AISI 52100 steel and between 0.51-0.56 against Si3N4 ceramic. We found thatwear occurred predominantly during the running-in period and it almost ceased at the steady friction stage. The wear rates of γ-Y2Si2O7 were in the order of 10-4mm3/(N m). Besides, wear debris strongly influenced the friction and wear processes. The strong chemical affinity between γ-Y2Si2O7 and AISI 52100 balls led to a thick transfer layer formed on both contact surfaces of the flat and counterpart ball, which changed the direct sliding between the ball and the flat into a shearing within the transfer layer. For the γ-Y2Si2O7/Si3N4 pair, a thin silica hydrate lubricant tribofilm presented above the compressed debris entrapped in the worn track and contact ball surface. This transfer layer and the tribofilm separated the sliding couple from direct contact and contributed to the low friction coefficient and wear rate.

Anodic deposition of porous RuO2 on stainless steel for supercapacitor studies at high current densities

Ruthenium dioxide is deposited on stainless steel (SS) substrate by galvanostatic oxidation of Ru3+. At high current densities employed for this purpose, there is oxidation of water to oxygen, which occurs in parallel with Ru3+ oxidation. The oxygen evolution consumes a major portion of the charge. The oxygen evolution generates a high porosity to RuO2 films, which is evident from scanning electron microscopy studies. RuO2 is identified by X-ray photoelectron spectroscopy. Cyclic voltammetry and galvanostatic charge–discharge cycling studies indicate that RuO2/SS electrodes possess good capacitance properties. Specific capacitance of 276 F g−1 is obtained at current densities as high as 20 mA cm−2 (13.33 A g−1). Porous nature of RuO2 facilitates passing of high currents during charge–discharge cycling. RuO2/SS electrodes are thus useful for high power supercapacitor applications.

Influence of roughness parameters and surface texture on friction during sliding of pure lead over 080 M40 steel

In the present investigation, tests were conducted on a tribological couple made of cylindrical lead pin with spherical tip against 080 M40 steel plates of different textures with varying roughness under both dry and lubricated conditions using an inclined pin-on-plate sliding tester. Surface roughness parameters of the steel plates were measured using optical profilometer. The morphologies of the worn surfaces of the pins and the formation of transfer layer on the counter surfaces were observed using a scanning electron microscope. It was observed that the coefficient of friction and the formation of transfer layer depend primarily on the surface texture of hard surfaces. A newly formulated non-dimensional hybrid roughness parameter called 'xi' (a product of number of peaks and maximum profile peak height) of the tool surface plays an important role in determining the frictional behaviour of the surfaces studied. The effect of surfaces texture on coefficient of friction was attributed to the variation of plowing component of friction, which in turn depends on the roughness parameter 'xi'.

Steel-concrete-steel composite columns subjected to lateral impact

Concrete-filled double skin tube (CFDST) is a creative innovation of steel-concrete-steel composite construction, formed by two concentric steel tubes separated by a concrete filler. Over the recent years, this column form has been widely used as a new sustainable alternative to existing structural bridge piers and building columns. Since they could be vulnerable to impact from passing vessels or vehicles, it is necessary to understand their behaviour under lateral impact loads. With this in mind, physical tests on full scale columns were performed using an innovative horizontal impact testing system to obtain the failure modes, the time history of the impact force, reaction forces and global lateral deflection as well as permanent local buckling profile of the columns. The experimental testing was complemented and supplemented by developing and using an advanced finite element analysis model. The model was validated by comparing the numerical results against experimental data. The findings of this study will serve as a benchmark reference for future analysis and design of CFDST columns.

Microscopic Frictional Response of Sodium Oleate Self-Assembled on Steel

The article peruses the frictional response of an important metal working lubricant additive, sodium oleate. Frictional force microscopy is used to track the response of molecules self-assembled on a steel substrate of 3–4 nm roughness at 0% relative humidity. The friction-normal load characteristic emerges as bell-shaped, where the peak friction and normal load at peak friction are both sensitive to substrate roughness. The frictional response at loads lower than that associated with the peak friction is path reversible while at higher loads the loading and unloading paths are different. We suggest that a new low-friction interface material is created when the normal loads are high.

Influence of surface texture and roughness parameters on friction and transfer layer formation during sliding of aluminium pin on steel plate

Surface texture of harder mating surfaces plays an important role during sliding against softer materials and hence the importance of characterizing the surfaces in terms of roughness parameters. In the present investigation, basic studies were conducted using inclined pin-on-plate sliding tester to understand the surface texture effect of hard surfaces on coefficient of friction and transfer layer formation. A tribological couple made of a super purity aluminium pin against steel plate was used in the tests. Two surface parameters of steel plates, namely roughness and texture, were varied in the tests. It was observed that the transfer layer formation and the coefficient of friction along with its two components, namely, the adhesion and plowing, are controlled by the surface texture and are independent of surface roughness (R-a). Among the various surface roughness parameters, the average or the mean slope of the profile was found to explain the variations best. Under lubricated conditions, stick-slip phenomena was observed, the amplitude of which depends on the plowing component of friction. The presence of stick-slip motion under lubricated conditions could be attributed to the molecular deformation of the lubricant component confined between asperities. (C) 2009 Elsevier B. V. All rights reserved.

Replacement of water on a steel substrate by a surrounding oil reservoir

With an objective to replace a water droplet from a steel surface by oil we study here the impact of injecting a hydrophilic/lipophilic surfactant into the droplet or into the surrounding oil reservoir. Contact angle goniometery, Grazing angle FTIR spectroscopy and Atomic force microscopy are used to record the oil/water interfacial tension, surface energetics of the substrate under the oil and water phases as well as the corresponding physical states of the substrates. Such energetics reflect the rate at which the excess surfactant molecules accumulate at the water/oil interface and desorb into the phases. The molecules diffuse into the substrate from the phases and build up specific molecular configurations which, with the interfacial tension, control the non-equilibrium progress of and the equilibrium status of the contact line. The study shows that the most efficient replacement of water by the surrounding oil happens when a surfactant is sparingly soluble in the supplier oil phase and highly soluble in the recipient water phase.

Phosphorus Partition between Liquid Steel and CaO-SiO2-P2O5-MgO Slag Containing Low FeO

CaO-SiO2-FeOx-P2O5-MgO bearing slags are typical in the basic oxygen steelmaking (BOS) process. The partition ratio of phosphorus between slag and steel is an index of the phosphorus holding capacity of the slag, which determines the phosphorus content achievable in the finished steel. The influences of FeO concentration and basicity on the equilibrium phosphorus partition ratios were experimentally determined at temperatures of 1873 and 1923 K, for conditions of MgO saturation. The partition ratio initially increased with basicity but attained a constant value beyond basicity of 2.5. An increase in FeO concentration up to approximately 13 to 14 mass pet was beneficial for phosphorus partition.

Semi-empirical procedures for estimation of residual velocity and ballistic limit for impact on mild steel plates by projectiles

This paper deals with the development of simplified semi-empirical relations for the prediction of residual velocities of small calibre projectiles impacting on mild steel target plates, normally or at an angle, and the ballistic limits for such plates. It has been shown, for several impact cases for which test results on perforation of mild steel plates are available, that most of the existing semi-empirical relations which are applicable only to normal projectile impact do not yield satisfactory estimations of residual velocity. Furthermore, it is difficult to quantify some of the empirical parameters present in these relations for a given problem. With an eye towards simplicity and ease of use, two new regression-based relations employing standard material parameters have been discussed here for predicting residual velocity and ballistic limit for both normal and oblique impact. The latter expressions differ in terms of usage of quasi-static or strain rate-dependent average plate material strength. Residual velocities yielded by the present semi-empirical models compare well with the experimental results. Additionally, ballistic limits from these relations show close correlation with the corresponding finite element-based predictions.