El-Sayed M. Sherif

A Comparative Study on the Electrochemical Corrosion Behavior of Iron and X-65 Steel in 4.0 wt % Sodium Chloride Solution after Different Exposure Intervals

In this work, the results obtained from studying the anodic dissolution of pure iron and API X-65 5L pipeline steel after 40 min and 12 h exposure period in 4.0 wt % NaCl solutions at room temperature were reported. Potential-time, electrochemical impedance spectroscopy, potentiodynamic polarization, and chronoamperometric current-time at constant potential techniques were employed. It has been found that the iron electrode corrodes in the chloride test solutions faster than the API X-65 5L steel does under the same conditions. Increasing the exposure period for the electrodes from 40 min to 12 h showed a significant reduction in the corrosion parameters for both iron and steel in the 4.0 wt % NaCl solution. Results together confirmed clearly that the X-65 steel is superior to iron against corrosion in sodium chloride solutions.

Synthesizing New Hydrazone Derivatives and Studying their Effects on the Inhibition of Copper Corrosion in Sodium Chloride Solutions

O-methoxybenzaldehydebenzoylhydrazone (O-MBH) and bis-(o-methoxybenzaldehyde)-thiocarbodihydrazone (O-MTH) were synthesized. The O-MBH and O-MTH effects on the inhibition of copper corrosion in 3.5% NaCl solution were investigated. Electrochemical measurements showed that the addition of O-MBH and O-MTH decreased the corrosion parameters of copper in the test solutions. The weight loss experiments indicated that O-MBH and O-MTH decreased the corrosion rate of copper. The data pointed out that O-MBH and O-MTH inhibit the copper corrosion in NaCl solution with inhibition efficiency in the order of O-MTH > O-MBH.

Antibacterial effect of carbon nanofibers containing Ag nanoparticles

Silver nanoparticles imbedded in polyacrylonitrile (PAN) nanofibers and converted into carbon nanofibers by calcination was obtained in a simple three-step process. The first step involves conversion of silver ions to metallic silver nanoparticles, through reduction of silver nitrate with dilute solution of PAN. The second step involves electrospinning of viscous PAN solution containing silver nanoparticles, thus obtaining PAN nanofibers containing silver nanoparticles. The third step was converting PAN/Ag composites into carbon nanofibers containing silver nanoparticles. Scanning electron microscopy (SEM) revealed that the diameter of the nanofibers ranged between 200 and 800 nm. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) showed silver nanoparticles dispersed on the surface of the carbon nanofibers. The obtained fiber was fully characterized by measuring and comparing the FTIR spectra and thermogravimetric analysis (TGA) diagrams of PAN nanofiber with and without imbedded silver nanoparticles, in order to show the effect of silver nanoparticles on the electrospun fiber properties. The obtained carbon/Ag composites were tested as gram-class-independent antibacterial agent. The electrosorption of different salt solutions with the fabricated carbon/Ag composite film electrodes was studied.

Corrosion Inhibition of Cast Iron in Arabian Gulf Seawater by Two Different Ionic Liquids

In this paper we report on the corrosion inhibition of cast iron in Arabian Gulf seawater by two different ionic liquids namely, 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) and 1-butyl-1-methylpyrrolidinium chloride ([Py1,4]Cl). The inhibiting influence of the employed ionic liquids was investigated by weight loss, open circuit potential electrochemical impedance spectroscopy, and cyclic potentiodynamic polarization. The results show the corrosion inhibition impact of the employed ionic liquids (ILs). Compared with [Py1,4]Cl, [EMIm]Cl shows a higher inhibition efficiency at a short immersion time, for the examined ILs concentrations. However, [Py1,4]Cl exhibits a higher efficiency upon increasing the immersion time indicating the persistence of the inhibiting influence. The corrosion inhibition of the employed ionic liquids is attributed to the adsorption of the cations of the ionic liquids onto the surface of cast iron forming a corrosion barrier.

Effects of Immersion Time and 5-Phenyl-1H-tetrazole on the Corrosion and Corrosion Mitigation of Cobalt Free Maraging Steel in 0.5 M Sulfuric Acid Pickling Solutions

The effect of exposure time and 5-phenyl-1H-tetrazole on the corrosion and corrosion mitigation of cobalt free maraging steel in 0.5 M H2SO4 pickling solutions has been reported using electrochemical and spectroscopic investigations. Potentiodynamic polarization data showed that the increase of immersion time from 0 min to 120 min increases the corrosion rate and decreases the polarization resistance of the maraging steel. On the other hand, the addition of PHTA and the increase of its concentration decrease all the corrosion parameters of the steel at all exposure test periods. Electrochemical impedance spectroscopy measurements agreed with the obtained polarization data. Scanning electron spectroscopy and energy dispersive X-ray investigations confirmed that the inhibition of the steel corrosion is achieved via the adsorption of the PHTA molecules onto the steel precluding its surface from being dissolved.

Corrosion and Corrosion Inhibition of High Strength Low Alloy Steel in 2.0 M Sulfuric Acid Solutions by 3-Amino-1,2,3-triazole as a Corrosion Inhibitor

The corrosion and corrosion inhibition of high strength low alloy (HSLA) steel after 10 min and 60 min immersion in 2.0 M H2SO4 solution by 3-amino-1,2,4-triazole (ATA) were reported. Several electrochemical techniques along with scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) were employed. Electrochemical impedance spectroscopy indicated that the increase of immersion time from 10 min to 60 min significantly decreased both the solution and polarization resistance for the steel in the sulfuric acid solution. The increase of immersion time increased the anodic, cathodic, and corrosion currents, while it decreased the polarization resistance as indicated by the potentiodynamic polarization measurements. The addition of 1.0 mM ATA remarkably decreased the corrosion of the steel and this effect was found to increase with increasing its concentration to 5.0 mM. SEM and EDS investigations confirmed that the inhibition of the HSLA steel in the 2.0 M H2SO4 solutions is achieved via the adsorption of the ATA molecules onto the steel protecting its surface from being dissolved easily.

Titanium Carbide Nanofibers-Reinforced Aluminum Compacts, a New Strategy to Enhance Mechanical Properties

TiC nanofibers reinforced Al matrix composites were produced by High Frequency Induction Heat Sintering (HFIHS).The titanium carbide nanofibers with an average diameter of 90 nm are first prepared by electrospinning technique and high temperature calcination process. A composite solution containing polyacrylonitrile and titanium isopropoxide is first electrospun into the nanofibers, which are subsequently stabilized and then calcined to produce the desired TiC nanofibers. The X-ray diffraction pattern and transmission electron microscopy results show that the main phase of the as-synthesized nanofibers is titanium carbide. The TiC nanofibers is then mixed with the aluminum powders and introduced into high frequency induction heat sintering (HFIHS) to produce composites of TiC nanofibers reinforced aluminum matrix. The potential application of the TiC nanofibers reinforced aluminum matrix composites was systematically investigated. 99.5% relative density and around 85 HV (833 MPa) Vickers hardness of the Al reinforced with 5 wt % TiC nanofiber has been obtained. Furthermore, the sample of Al contains 5 wt % TiC, has the highest value of compression and yield strength of about 415 and 350 MPa, respectively. The ductility of the Al/5 wt % TiC showed increasing with increasing the TiC contents.

Corrosion Behavior of Cast Iron in Freely Aerated Stagnant Arabian Gulf Seawater

In this work, the results obtained from studying the corrosion of cast iron in freely aerated stagnant Arabian Gulf seawater (AGS) at room temperature were reported. The study was carried out using weight-loss (WL), cyclic potentiodynamic polarization (CPP), open-circuit potential (OCP), and electrochemical impedance spectroscopy (EIS) measurements and complemented by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) investigations. WL experiments between two and 10 days’ immersion in the test electrolyte indicated that the weight-loss the cast iron increases with increasing the time of immersion. CPP measurements after 1 h and 24 h exposure period showed that the increase of time decreases the corrosion via decreasing the anodic and cathodic currents, as well as decreasing the corrosion current and corrosion rate and increasing the polarization resistance of the cast iron. EIS data confirmed the ones obtained by WL and CPP that the increase of immersion time decreases the corrosion of cast iron by increasing its polarization resistance.

The Role of Corrosion Inhibitors in Protecting Metallic Structures against Corrosion in Harsh Environments

The present review discusses the latest reported studies on the role of corrosion inhibitors in mitigating the corrosion of metals and alloys in corrosive aqueous media and in the atmosphere. Included is basic information about inhibitors such as their definitions, classifications, efficiencies, and applications in the industrial sector as well as the most frequently used techniques, either conventional or nonconventional, to evaluate their efficiencies in controlling corrosion. Corrosion inhibitors are usually chemical compounds used in low concentrations to mitigate the corrosion rate of metallic materials when they are in contact with aggressive media. The use of corrosion inhibitors in this regard has been one of the most successful methods in minimizing corrosion in aqueous solutions and in the atmosphere. Compounds with this feature are classified as passivating, cathodic, organic, precipitation, and volatile corrosion inhibitors. Each class of these inhibitors is divided into subcategories that reflect their mechanism in controlling the corrosion rate either by decreasing the severity of the surrounding environment or by modifying or blocking the surface of the material to be protected. This review also reports the evaluation of the inhibition efficiency of corrosion inhibitors by using both conventional and modern measuring techniques. Conventional methods include the use of gravimetric weight-loss, electrochemical anodic, linear, cathodic, and cyclic polarization, and chronoamperometric current-time techniques. The nonconventional tests involve employing the electrochemical impedance spectroscopy and electrochemical quartz crystal microbalance. The characterization of the surface of the materials after being inhibited is usually performed by scanning electron microscopy, infrared spectroscopy, UV-visible spectroscopy, energy dispersive X-ray analyzer, and so on. Also covered in this chapter is the use of corrosion inhibitors in industry.

Anodic Dissolution of API X70 Pipeline Steel in Arabian Gulf Seawater after Different Exposure Intervals

The anodic dissolution of API X70 pipeline steel in Arabian Gulf seawater (AGSW) was investigated using open-circuit potential (OCP), electrochemical impedance spectroscopy (EIS), cyclic potentiodynamic polarization (CPP), and current-time measurements. The electrochemical experiments revealed that the X70 pipeline steel suffers both general and pitting corrosion in the AGSW solution. It was found that the general corrosion decreases as a result of decreasing the corrosion current density (), corrosion rate () and absolute currents as well as the increase of polarization resistance of X70 with increasing the exposure time. On the other hand, the pitting corrosion was found to increase with increasing the immersion time. This was confirmed by the increase of current with time and by the SEM images that were obtained on the steel surface after 20 h immersion before applying an amount of 0–.35 V versus Ag/AgCl for 1 h.