Search results

This study aims to assess the performance of SAF 2205 duplex stainless steel against pure wear, tribo-corrosion, corrosion and the synergism between wear and corrosion. The effect of plasma nitriding conducted at low temperature (380°C) on SAF 2205 steel was analyzed.

Three systems were used for assessing the synergism between wear and corrosion: tribo-corrosion – wear tests conducted using the micro-scale abrasion test, performed under a slurry of alumina particles containing 3.5% NaCl; pure wear – tests conducted using the previous system but isolated in a glovebox with a 99% N2 atmosphere; and cyclic polarization under 3.5% NaCl solution. A hard nitrided layer of 3 µm thickness was characterized using X-ray diffraction, presenting expanded austenite.

The wear mode after micro-scale abrasion tests changed in the absence of an oxygen atmosphere. During pure wear, a mixed mode was identified (rolling + grooving), with the grooving mode more intense for the untreated steel. For tribo-corrosion tests, only rolling wear was identified. For all cases, the nitrided samples presented less wear. The corrosion results indicated a higher repassivation potential for the nitrided condition.

The synergism was more positive for the nitrided sample than for the untreated one, which can be considered for surface treatments of duplex stainless steels in practical applications.

A detailed description of wear mechanisms showed a significant change in the presence of oxygen atmosphere, a new approach for isolating pure wear.

Sodium oleic sulfonate (SOS), polyoxyethylene (20) sorbitan monooleate (Tween 80 or T₈₀) and their mixtures have been studied as acid corrosion inhibitors for mild steel in 1M HCl using adsorption and gravimetric techniques. All the data reveal that the compounds act as inhibitors in the acid environment. The adsorption and inhibition efficiency are discussed as a function of the concentration and the nature of mixing the two surfactants. T₈₀ + α_SOS mixtures show a better inhibition effect than SOS + α_T80, that increases with the value of α_SOS. The interaction and synergism of the investigated mixtures are studied by calculating the interaction parameters (β) and the degree of synergism (S) from surface tension‐concentration and corrosion data. The degree of synergism for T₈₀ + α_SOS is higher than that of SOS + α_T80. This is believed to be due to the presence of the small amount of the co‐surfactant SOS which serves as an anchor molecule for the nonionic molecules.

This paper aims to explain the modern unintended human-personal self-destruction and the importance of diverse society-specific holistic cultures (“native cultures”) and social value systems as the remedy.

This paper is a viewpoint, as both the explanation and the proposed remedy are based on the present author’s historical, theoretical and normative considerations.

First, the author’s interpretation of pre-modern to modern Western societies reveals that some important pre-modern Western values are given to the modern era as part of the market value system. Second, some Mercantilist ideas have strong influences on Classical economic theory and methodology. Third, the modern Western value system – the market value system – corresponds to the Core Synergism of Modern Civilization or the complex driving force of Modern Civilization.

This paper is designed to facilitate reflection on the excessive emphasis on economic/market values.

The present author’s normative framework for social value system (“integral harmony”) is used for explaining a likely remedy of the unintended human-personal self-destruction. Also, for solving the human-personal predicament, this article integrates native culture, balance and harmony into economic thinking to promote sustainable development for a viable human future. Concluding remarks provide a summary for clarification of the remedy.

Meticulous formulation is required to optimize performance of non‐toxic corrosion inhibitors. The proper loading level and pigment volume concentration must be obtained. The old adage “more is better” does not apply to these new pigments. While research is still underway to find the perfect replacement for leads and chromes, formulators today need techniques which will help them now. It has been found that several of today’s non‐toxic corrosion inhibitors can work synergistically with each other to produce performance greater than either one can alone. This paper will summarize some of the results found by the proper combination of non‐toxic anti‐corrosive agents.

The aim of this paper is to investigate the synergism effect between lanthanum salt (La(NO₃)₃) and benzotriazole (BTAH) on the corrosion inhibition of commercial brass and to further study the inhibition mechanism.

Potentiodynamic polarization curves were carried out on bare brass and brass treated with additions of optimum concentration of BTAH, La salt and La salt+BTAH to the basal deposition solutions in 3.5 wt. percent sodium chloride solution. The inhibition mechanism of the composite conversion coatings on brass obtained in optimal deposition techniques were investigated by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), X‐ray diffraction (XRD), and FT‐IR reflection spectra.

A “Critical La(NO₃)₃ content” and “Critical BTAH content” were both observed, at which the coatings prepared performs the highest protectiveness, and La(NO₃)₃ and BTAH had an excellent synergism effect on the corrosion inhibition of brass. The corrosion mechanisms for uncoated and coated brass are different. A remarkable enhancement of the brass's corrosion protection was obtained by the formation of composite conversion coatings consisted of Cu(I)BTA and La coordinate thing except for Cu₂O and La₂O₃, which acted as a barrier avoiding the release of metal ions and inhibited the diffusion of the oxygen.

The results from this paper showed that La(NO₃)₃ and BTAH could be used together to prepare the novel composited conversion coatings on commercial brass for the good corrosion inhibition.

Politics in human societies represents a variation, and elaboration, on a major evolutionary theme. Political processes have played an important functional role in goal-oriented, cooperative social systems in the natural world. This view of politics is also consistent with a causal theory – known as the Synergism Hypothesis – which explains the rise of complexity in evolution over time and, equally important, the frequent examples of devolution and dissolution. In addition to a brief discussion of this theory, the evolution of political systems in humankind will be described, from its possible origins among our remote australopithecine ancestors to the emergence of complex modern civilizations. Now, however, we confront an existential threat to our species, and to many others, due mainly to climate change. The future is very problematic. I will argue here that the only viable path going forward is a new social contract coupled with (democratic) global governance – a global “superorganism.”

The aim of this work is to study the tribocorrosion behaviors of Hastelloy C276 alloy sliding against AISI 316 stainless steel in artificial seawater and distilled water.

The electrochemical behaviors of Hastelloy C276 alloy are measured by potentiodynamic polarization method. The tribocorrosion properties are evaluated using an MRH-03 type ring-on-block test rig in artificial seawater with different salinity. The wear loss is determined by the difference of sample weight before and after tribocorrosion tests.

The results show that the typical passivation behavior is observed for C276 alloy in seawater. The Hastelloy C276 alloy has the maximum corrosion current density in 3 percent seawater, which is the synergism of salt concentration and dissolved oxygen in seawater. Friction coefficients are in general larger in distilled water compared with seawater. The wear loss in seawater is always higher than that in distilled water for both alloys. Seawater could reduce the friction coefficient and the wear resistance.

Many scientists focused on studying the friction behavior of passive metals sliding against alumina or zirconia, which was considered to act as inert antagonist in the experiments. However, there are few papers available on the tribocorrosion properties of passive metals sliding each other in corrosion mediums.

Some thiourea derivatives, non‐ionic surfactants and their synergism when used simultaneously were evaluated for their efficiency as corrosion inhibitors for mild steel in 1N H₂SO₄ solution at different temperatures (303, 313 and 323K). A marked inhibition synergism occurred within an optimum concentration range even at higher temperature. The thiourea derivatives obey the Langmuir adsorption isotherm. The effect of these compounds on the corrosion behaviour of carbon steel was studied using open circuit potential measurements and potentiodynamic polarization measurements. These data were utilized to calculate activation energy.

The inhibition efficiency of the HEDP‐Zn²⁺ system, in a wider concentration range of Zn²⁺ and HEDP (10, 50, 100, 150, 200 and 300ppm), in controlling corrosion of mild steel immersed in low chloride medium (Cl^‐ = 60ppm) has been evaluated by weight‐loss study. Synergism parameters have been calculated between HEDP and Zn²⁺. The plot of C/θ vs. C gives a straight line. The HEDP‐Zn²⁺ system functions as a mixed inhibitor. The protective film has been analysed by UV‐visible reflectance spectra and X‐ray diffraction.

The synergistic influence caused by iodide ions on the inhibition of corrosion of mild steel in 0.5M H₂SO₄ in the presence of n‐hexyl amine (n‐HA) has been studied using potentiodynamic polarization, linear polarization and a.c impedance technique. n‐HA accelerates the corrosion of mild steel at lower concentrations but inhibits the corrosion at higher concentrations. The addition of iodide ions enhances the inhibition efficiency to a considerable extent. The adsorption of this compound is found to obey Temkin’s adsorption isotherm. The increase in surface coverage in the presence of iodide ions indicates that iodide ions enhance the adsorption of n‐HA on the metal surface. Defines and evaluates synergism parameter (S_I). Values of the parameter which are more than unity indicate the fact that the enhanced inhibition efficiency in the presence of iodide ions is only due to synergism and there is a definite contribution from the inhibitor molecule. n‐HA is then adsorbed by coulombic interaction on the metal surface, where iodide ions are already adsorbed, and thus reduces the corrosion rate.