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Cyclic voltametry and potentiodynamic single sweep techniques are used to study the electrochemical behaviour of lead in Na₂CO₃ solutions containing various concentrations of ClO₄^‐ as aggressive anion. The effects of different concentrations, in terms of destruction of passivity and initiation of pitting corrosion, were monitored with reference to the change in integrated anodic charge. It was found that Δq_a (taken as a measure of the extent of pitting) varies linearly with log C_ClO4‐. The pitting corrosion potential, E_pitting, varies with log C_ClO4‐ according to sigmoidal curves. These curves are explained on the basis of formation of passive, active and continuously propagating pits. Additions of aliphatic amines shift the pitting corrosion potential, E_pitting, into the noble (positive) direction, indicating the inhibition action of the added amines on the pitting attack. E_pitting varies with the logarithm of the inhibitor concentration according to: E_pitting = a + b log C_inh. The inhibition of pitting corrosion by the aliphatic amines is assumed to be due to either competitive adsorption between the CO₃^2– with ClO₄^‐ anions, and/or the chemisorption of the amine on the metal with the formation of a metal‐nitrogen coordination bond. The efficiency of these compounds as pitting corrosion inhibitors increases with the increase in the chain length of the alkyl group.

The peristaltic motion for Carreau fluid by means of an infinite train of sinusoidal waves traveling along the walls of a circular cylindrical flexible tube is investigated. The fluid is subjected to a constant transverse magnetic field. A perturbation solution is obtained for the case in which Weissenberg number is small. The effects of Hartmann number, Weissenberg number, power‐law index and amplitude ratio on the pressure rise and the friction force are discussed. The trapping limit and the trapping occurrence region at the centerline decrease by increasing Hartmann number but they are independent approximately of Weissenberg number and power‐law index.

The effect of the addition of aggressive salts such as LiCl, NaCl, KCl, RbCl and MgCl2 on the steady‐state potential of a Zn electrode previously equilibrated in a passivating chromate solution is established. S‐shaped curves are obtained for the variation of the steady‐state potential with the quantity of aggressive salt added. For each inhibitor concentration, Cinh, the addition of aggressive ions up to a certain concentration has no effect on the passivity of Zn. However, higher Cl ion concentration causes destruction of the passive film and initiation of pitting corrosion. Destruction of passivity occurs after an induction period which decreases with the increase in the concentration of the attacking ion and/or the decrease in that of the inhibiting ions. The concentration of aggressive ion, Cagg, that can be tolerated by a certain concentration of the inhibiting ions, Cinh, is given by the relation : log Cinh =K + n log CCl−, where K and n are constants. The efficiency of these salts in initiating pitting corrosion increases in the order RbCl ≤ MgCl2, ≤ KCl < NaCl < LiCl. The change in the degree of aggressivity of these salts could be attributed either to the incorporation of the cations in the passive film or to their effect on pH.

In order to determined the characteristics of peristaltic transport of the Newtonian fluid with variable viscosity through a cylindrical tube having walls that are transversely displaced by an in finite, harmonic traveling wave of large wavelength and negligibly small Reynolds number was analyzed in the presence of magnetic field directed with an angle π A perturbation method of solution is thought. The viscosity parameter a <<1 is chosen as a perturbation parameter. It serves as a model for the study of flow of chyme through small intestines. The governing equations are developed up to first‐order in the viscosity parameter (a). In case of the first‐order system, simpling a complicated group of products of Bessel functions by approximating polynomial. The results show that, the increasing of magnetic field increases the pressure rise. Also, the pressure rise at normal magnetic field (ω=π/2) is greater than the pressure rise at inclined magnetic field (O<ω>π/2). In addition, the pressure rise increases as the viscosity parameter decreases at certain values of flow rate. Comparisons with other studies are given.

The potentiodynamic anodic polarization curves for the lead electrode were obtained in 0.1 mol L‐1 KOH solution in the absence and presence of C103‐ or C104‐ as aggressive ions at different concentrations. Lower concentrations of these ions have no significant influence on the passive film, while higher concentrations raise the active dissolution current density, and cause destruction of passivity and initiation of pitting corrosion. The critical pitting corrosion potential varies with the concentration of the aggressive ions according to sigmoidal curves. These curves were explained on the basis of the formation of passivitable, active and continuously propagagting pits depending on the range of the aggressive ion concentration. Additions of increasing concentrations of chromate, phosphate, sulphate and carbonate ions cause a shift of the critical pitting potential in the noble direction accounting for increase resistance to pitting attack (inhibition). The pitting corrosion potential varies with the concentration of the inhibitive ions, in the presence of a constant concentration of the aggressive ions, according to curves of sigmoidal shape. From these curves one can determine the minimum concentration of the inhibitive ions necessary for inhibition of pitting corrosion to occur.

The electrochemical behaviour of zinc in different concentrations of Na₂SO₄ (pH = 6.0) was investigated using the potentiodynamic anodic polarization single sweep and cyclic voltammogram techniques. The anodic portion is characterized by one distinct peak corresponding to Zn(OH)₂ or ZnO. This is followed by a passive region up to a certain potential; the passive current suddenly rises steeply without any sign of oxygen evolution. This denotes the breakdown of the passive film and initiation of pitting corrosion. It was found that the breakdown potential depends on the sulphate concentration, type of aeration, scan rate, solution temperature and pH. The pitting initiation may be explained through the adsorption of SO₄^2– anion on the oxide film formed. This decreases the repair efficiency and causes further metal dissolution. From the cyclic voltammogram of zinc in different concentrations of Na₂SO₄, it was found that the change in the integrated anodic charge, Δq_a, which is taken as a measure of the extent of pitting, varies linearly with concentration of SO₄^2– anion.

Results and discussion Adsorption isotherms of stearic acid on the surface of manganese ore samples:

The purpose of this paper is to study the electrochemical behavior of Sn electrode in Na₂B₂O₇ solutions in the absence and presence of NaNO₃ as a pitting corrosion agent.

The electrochemical behavior of Sn electrode was studied by using cyclic voltammetry and potentiodynamic polarization measurements and complemented with scanning electron microscopy examinations.

This paper shows that in the absence of NO₃ − ions, the anodic polarization of Sn electrode exhibits active/passive transition. Addition of various concentrations of NO₃ − anions to the borate solution enhances active anodic dissolution and tends to break down the passive oxide film at a certain pitting potential. The pitting potential, and hence the pitting corrosion resistance, decreases with increasing NO₃-ion concentration and temperature but increases with scan rate and repetitive cycling. Addition of CrO₄²⁻, WO₄²⁻ or MoO₄²⁻ oxyanions to the borate nitrate solution inhibits the pitting corrosion of Sn.

This is the first study that shows the effect of NO₃ − ion as a pitting corrosion agent.

This paper aims to study the physical and chemical characteristics of inkjet titanium dioxide inks for cotton fabric digital printing.

Different dispersing agents through the reaction of glycerol monooleate and toluene diisocyanate were prepared and then performed by using three different polyols (succinic anhydride-modified polyethylene glycol PEG 600, EO/PO Polyether Monoamine and p-chloro aniline Polyether Monoamine), to obtain three different dispersing agents for water-based titanium dioxide inkjet inks. The prepared dispersants were characterized using FTIR to monitor the reaction progress. Then the prepared dispersants were formulated in titanium dioxide inkjet inks formulation and characterized by particle size, dynamic surface tension, transmission electron microscopy, viscosity and zeta potential against commercial dispersants. Also, the study was extended to evaluate the printed polyester by using the prepared inks according to washing and crock fastness.

The obtained results showed that p-chloro aniline Polyether Monoamine (J) and succinic anhydride modified polyethylene glycol PEG 600 (H) dispersants provided optimum performance as compared to commercial standards especially, particle size distribution data while EO/PO Polyether Monoamine based on dispersant was against and then failed with the wettability and dispersion stability tests.

These ink formulations could be used for printing on cotton fabric by DTG technique of printing and can be used for other types of fabrics.

The newly prepared ink formulation for digital textile printing based on synthesized polyurethane prepolymers has the potential to be promising in this type of printing inks, to prevent clogging of nozzles on the printhead and to improve the print quality on the textile fiber.

Modifies short and medium alkyd resins using perfluori‐nated urethane toluene isocyanate (PFUTI), and incorporates the modified resins in a set of paint formulations containing different ratios of zinc phosphate as an inhibitive pigment. Achieves promising results and illustrates corrosion‐protective properties in various paint formulations and also a paint formulation free of the inhibitive pigment. Shows enhancement of the corrosion protection efficiencies by the improvement in the hydrophobicity of alkyd resin modified with PFUTI. In view of these results, minimizes or neglects the most expensive inhibitive pigments from an economical standpoint.