Analyze and modelingofdamage behavior of a C0.12%Mn1.02%Si0.29% HLE steel solicited in selected physicochemical medium

The influence of environment and physical parameters on C0.12%Mn1.02%Si0.29% HLE steel steel corrosion damage behaviour in NaCl solutions was studied using weight loss, pH evolution at 300k to 370k, electro-exchanges, and passivity. Herein, the results show that the corrosion rate changes versus type of thermal treatment and cooling fluid, solution concentration, shape, size and cooling speed of the samples. The resolution of Nernst equation proves that the increase in temperature has a direct effect on hydrogen potential of the solution, current and corrosion potential of the metal. Moreover, the inhibition efficiency was determined by theoretical calculation using mechanical molecular and semi-empirical method. These results guided us to conclude that the inhibitor, which has low electronegativity than C0.12%Mn1.02%Si0.29% Steel has good efficienc

Kinetic, Isotherm and Thermodynamic Analysis on Adsorption of Cr(VI) Ions from Aqueous Solutions by Synthesis and Characterization of Magnetic-Poly(divinylbenzene-vinylimidazole) Microbeads

The magnetic-poly(divinylbenzene-1-vinylimidazole) [m-poly(DVB-VIM)] microbeads (average diameter 53–212 μm) were synthesized and characterized; their use as adsorbent in removal of Cr(VI) ions from aqueous solutions was investigated. The m-poly(DVB-VIM) microbeads were prepared by copolymerizing of divinylbenzene (DVB) with 1-vinylimidazole (VIM). The m-poly(DVB-VIM) microbeads were characterized by N2 adsorption/desorption isotherms, ESR, elemental analysis, scanning electron microscope (SEM) and swelling studies. At fixed solid/solution ratio the various factors affecting adsorption of Cr(VI) ions from aqueous solutions such as pH, initial concentration, contact time and temperature were analyzed. Langmuir, Freundlich and Dubinin–Radushkvich isotherms were used as the model adsorption equilibrium data. Langmuir isotherm model was the most adequate. The pseudo-first-order, pseudo-second-order, Ritch-second-order and intraparticle diffusion models were used to describe the adsorption kinetics. The apparent activation energy was found to be 5.024 kJ mol−1, which is characteristic of a chemically controlled reaction. The experimental data fitted to pseudo-second-order kinetic. The study of temperature effect was quantified by calculating various thermodynamic parameters such as Gibbs free energy, enthalpy and entropy changes. The thermodynamic parameters obtained indicated the endothermic nature of adsorption of Cr(VI) ions. Morever, after the use in adsorption, the m-poly(DVB-VIM) microbeads with paramagnetic property were separeted via the applied magnetic force. The magnetic beads could be desorbed up to about 97% by treating with 1.0 M NaOH. These features make the m-poly(DVB-VIM) microbeads a potential candidate for support of Cr(VI) ions removal under magnetic field

Neutralization degree effect on viscosimetric behaviour of hydrolyzed polyacrylamide-poly(4-vinylpyridine) [AD37-P4VP] mixture in aqueous solution

cited By 7International audienceIn the present work, we describe the dependence of the 27 % hydrolyzed polyacrylamide [AD37]-poly(4-vinylpyridine) [P4VP] mixture reduced viscosity as a function of the neutralization degree of P4VP polymer, in aqueous solutions at 25 °C. Measurements are performed using the viscosimetry technique. Viscosity results showed that the polymer chains expanded at low neutralization degrees (α1). We note that the viscosity get a maximum at α≈0.86 © 2008 Springer-Verlag

Magnetic properties of as-cast and nanocrystallized Fe 73,5

This work concerns the study of soft iron-based magnetic materials. More specifically, concerning based iron amorphous materials, it will be done by combining structure and magnetic properties while acting on various parameters, by annealing to characterize the nanocrytallization. An experimental approach of magnetic properties is applied to the amorphous or nanocrystalline ultra soft materials evaluation of power losses, permeability as properties of the cycle of hysteresis. According to the scale of constraints and the nature of heat treatment (without magnetic field or magnetic field), it is induced an anisotropy which changes the magnetization properties. Thus, for ferromagnetic amorphous alloys, the anisotropy induced constraints is eliminated giving rise to a uniaxial anisotropy. FeBSi amorphous type materials can therefore, after introduction of copper (multiplication of germs) and niobium (growth inhibition), get nanocrystallized compositions of Fe73,5Cu1Nb3Si13,5B9 after annealing around of 500 - 600 °C

Characterization by Tga and Uv-visible of new pigment materials containing mica, P4VP and D&C red 6 dye

DOI: 10.3303/CET1332356International audienceThe pigments and dyes industry must constantly develop new products with more innovative visual effects. Various industrial sectors such as cosmetics, textile fibers, painted paper and ceramics...etc, need new optical effects for their commercial products. The field of study of these pigments is vast and the market is in full expansion. Among the desired optical effects, manufacturers try to imitate nature by creating the appearance of increasingly sophisticated products: for example interferential compounds changing color and aspect under the effect of the light and according to angle. These effects can be achieved through the existence of highly ordered structures defined and organized within compounds to be developed. In our work, we succeeded in formulating new pigmentary materials by adsorption of polymer on mica particles and fixation of D&C Red 6 dyes on polymer. These new pigmentary materials can either differ by their colors, or to present interferential effects. Copyright © 2013, AIDIC Servizi S.r.l

Viscosimetric behaviour of hydrolyzed polyacrylamide-poly(4-vinylpyridine) [AD37-P4VP] mixture in aqueous solution

cited By 16International audienceThe interactions between 27% hydrolyzed polyacrylamide [AD37] and poly(4-vinylpyridine) [P4VP], in aqueous solutions and at neutralization degree α = 1, were studied by using viscosimetry technique. The reduced viscosities of these copolymer mixture solutions, at 25 °C, reach several orders of magnitude higher than the reduced viscosity of each polymer taken separately, and according to the ratio R of the chain numbers. Intermolecular electrostatic associations are favoured by increasing the P4VP concentration corresponding to high R values. Thus, mixtures rich in P4VP are characterized by a high decrease in the viscosity due to interpolymer complete complexation AD37-P4VP, leading to the totally contraction or collapse of the polymer chains. Strongest reduced viscosities, due to the inter-chain AD37 associations, are observed for the mixtures poor in P4VP (so the weakest ratios R of the chain numbers). In order to understand the relative effects of these two polymers on the reduced viscosity, two mixtures containing the same total quantity are compared. Reduced viscosities of each copolymer alone strongly increase by dilution of the aqueous solution. In the case of the mixture, an opposite behaviour is observed with a reduction in the reduced viscosity by dilution. So, the increase of the reduced viscosity according to AD37 concentration, at α constant, shows an intra and an inter-chain associative phenomenon. © 2006 Elsevier Ltd. All rights reserved

Rheological behavior study of cationic surfactant-polyelectrolyte complex (AD37/P4VP-DPC) in aqueous medium

cited By 1International audiencePolyelectrolyte 27% hydrolyzed polyacrylamide-poly(4-vinylpyridine) (AD37-P4VP) complex with cationic surfactant dodecylpyridinium chloride (DPC) interactions in aqueous solution, is investigated by rheological measurements, at 20-°C with a fixed neutralization degree α-=-0.1. The results show that the interaction of complex (AD37-P4VP) is favored in the presence of the DPC where the electrostatic interactions are dominant. This interaction is governed by electrostatic and hydrophobic interactions. In the presence of salt, it is more cooperative. Three rheological behaviors are determined of this system show a shear thinning behavior, shear thickening for the strong shear rate and a newtonian behavior. Then, we determine the rheological models of the system to different concentration of P4VP in the presence and absence of salt to justify the rheological behavior of the complex.