1M H2SO4 Solution Research Articles

Experimental and theoretical study of [N-substituted] p-aminoazobenzene derivatives as corrosion inhibitors for mild steel in sulfuric acid solution

[N-substituted] p-aminoazobenzene derivatives (1), (2), (3), (4) and (5) were prepared and investigated as corrosion inhibitors for mild steel in 1M H2SO4 solution by weight loss measurements. It has been observed that the corrosion rate decreases, inhibition efficiencies increase and surface coverage degree increases with increasing inhibitor concentration. Inhibition efficiencies for prepared compounds were ordered: (1)>(2)>(5)>(4)>(3) with the highest inhibiting efficiency of 63% for 10−3M. The values of ΔGadso are showing physisorption effect for all prepared compounds. Semiempirical molecular orbital calculations for (1), (2), (3), (4) and (5) could be used as a useful tool to obtain information for explaining the nature of interaction between the metal surface and the organic molecule as a corrosion inhibitor.

Tribocorrosion characteristics of laser deposited Ti–Ni–ZrO2 composite coatings on AISI 316 stainless steel

The tribocorrosion characteristics of laser deposited titanium–nickel–zirconia composite coatings onto AISI 316 substrates have been investigated. Feedstock powders were blended at varying compositions and deposited onto AISI 316 using Nd:YAG high power laser beam at varying scan speeds. The relationships between laser speed, structure and tribocorrosion properties of the synthesised composite coatings were studied. The corrosion and tribocorrosion behaviour of the coatings was studied in 1M H2SO4 solution using a potentiodynamic polarisation technique. The coatings displayed fine and slightly porous structures with relatively well dispersed constituent elements. The Ti–Ni coatings deposited under 0.0067m/s had the highest corrosion resistance while addition of 5% zirconia to the Ti–Ni coatings significantly improved its tribocorrosion resistance.

Highly porous carbon spheres for electrochemical capacitors and capacitive flowable suspension electrodes

In flowable and conventional electrochemical capacitors, the energy capacity is largely determined by the electrode material. Spherical active material, with high specific surface area (SSA) represents a promising material candidate for film and flow capacitors. In this study, we synthesized highly porous carbon spheres (CSs) of submicrometer size to investigate their performance in film and suspension electrodes. In particular, we studied the effects of carbonization and activation temperatures on the electrochemical performance of the CSs. The CSs activated at optimum conditions demonstrated narrow pore size distribution (<3nm) with high SSA (2900m2/g) and high pore volume (1.3cc/g), which represent significant improvement as compared to similar materials reported in literature. Electrochemical tests of CSs in 1M H2SO4 solution showed a specific capacitance of 154 F/g for suspension electrode and 168 F/g for film electrode with excellent rate performance (capacitive behaviors up to 100mV/s) and cycling performance (95% of initial capacitance after 5000 cycles). Moreover, in the film electrode configuration, CSs exhibited high rate performance (78 F/g at 1000mV/s) and volumetric power density (9000W/L) in organic electrolytes, along with high energy density (21.4Wh/L) in ionic liquids.

Electrochemical noise investigation of Aloe plant extract as green inhibitor on the corrosion of stainless steel in 1 M H2SO4

The inhibition action of Aloe Vera leaf extract as environmentally friendly inhibitor for the corrosion protection of stainless steel in 1M H2SO4 solution was studied by electrochemical techniques as well as scanning electron microscope. The results of linear polarization and electrochemical impedance spectroscopy proved the effectiveness of Aloe Vera extract as concentration increased. Corrosion inhibition of Aloe extract was also studied by electrochemical noise (EN). Employing EN, different aspects like transient analysis, noise resistant and characteristic charge were characterized. Moreover, a literature review of Aloe Vera characterization using high-performance liquid chromatography and GC-MS was carried out.

Characterization of corrosion inhibition performance of azole compounds through power spectral density of electrochemical noise

The power spectral density was focused to analyze the electrochemical noise data of stainless steel samples dipped in 1M H2SO4 solution without and with different concentrations of benzotriazole and benzothiazole corrosion inhibitors. Accordingly, a good correlation was observed between corrosion intensity and PSD (I) and PSD (V) distributions calculated for each frequency point as a percentage of total energy, over the frequency domain. In addition to indicating the inevitable role of PSD distribution in determining characteristic charge from shot noise theory, an approach was developed to choose minimum frequency range to calculate q, in particular for the systems with different types of PSD distributions.

Anti-corrosion performance of nanostructured poly(aniline-co-metanilic acid) on carbon steel

In order to investigate the effect of a strongly hydrophilic substituent group on the anticorrosion properties of polyaniline (PANI) coatings, sulfonic acid groups (SO3H) were introduced into the polyaniline molecular structure by the copolymerization of aniline (ANI) and 3-aminobenzenesulfonic acid (metanilic acid, MA), using ammonium persulfate as an oxidant. The MA/ANI monomer ratio of the poly(aniline-co-metanilic acid) (PANIMA) products was systematically varied in the range 0–1. The PANIMA copolymers contained sulfur in the following forms: HSO4− from the external dopant (H2SO4 obtained from the reduction of the persulfate oxidant) or SO3H groups from the external MA dopant, and SO3H groups from the metanilic copolymerization unit. The influence of HSO4− or SO3H in the external dopant and SO3H in the copolymerization unit on the anticorrosive properties of PANIMA was observed. The morphologies of the different PANIMA products were characterized by SEM. At low MA/ANI ratios, PANIMA nanofibres formed whereas at near stoichiometric MA/ANI ratios PANIMA nanogranules were obtained. The chemical structure of the PANIMA products was determined by FTIR, UV–vis spectroscopy and XRD. The anti-corrosion behavior of PANIMA coated carbon steel electrodes was investigated in 1M H2SO4 solutions by the potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS). Results show that the PANIMA coatings offer good anti-corrosion protection to carbon steel in 1M H2SO4 solutions, with the degree of protection depending on the sulfonic acid group and HSO4− dopant content in the coatings. Low sulfur content in the PANIMA coatings afforded the best protection, though the performance of all PANIMA coatings was inferior to PANI itself under the applied testing conditions.

Corrosion Inhibition Effects of Some New Synthesized N-Aroyl-N\ -Aryl thiourea Derivatives for Carbon Steel in Sulfuric Acid Media

This research includes the synthesis of some new N-Aroyl-N -Aryl thiourea derivatives namely: N-benzoyl-N -(p-aminophenyl) thiourea (STU1), N-benzoyl-N -(thiazole) thiourea (STU2), N-acetyl-N ` -(dibenzyl) thiourea (STU3). The series substituted thiourea derivatives were prepared from reaction of acids with thionyl chloride then treating the resulted with potassium thiocyanate to affored the corresponding N-Aroyl isothiocyanates which direct reaction with primary and secondary aryl amines, The purity of the synthesized compounds were checked by measuring the melting point and Thin Layer Chromatography (TLC) and their structure, were identified by spectral methods [FTIR, 1 H-NMR and 13 C-NMR].These compounds were investigated as a corrosion inhibitor for carbon steel in 1M H2SO4 solution using weight loss, potentiostatic polarization methods; the obtained results showed that the substituted thioureas retard both cathodic and anodic reactions in acid media, by virtue of adsorption on the carbon steel surface. This adsorption obeyed Langmuir’s adsorption isotherm. The inhibition efficiency of (STU1-3) is ranging between (60-95)%. By using different (STU3) derivative concentration and temperature, the carbon steel corrosion rate was decreased with increasing (STU3) concentration and the highest inhibition efficiency reach to 98.5% by using 5×10 -4 M (STU3) concentration at 338 K, the inhibition efficiency increases with increasing temperature in the range of (308-338)K.

Microstructure and corrosion behavior of multipass gas tungsten arc welded 304L stainless steel

The purpose of this study was to discuss the effect of single pass and multipass (double and triple pass) gas tungsten arc welding (GTAW) on microstructure, hardness and corrosion behavior of 304L stainless steel. In this investigation, 308 stainless steel filler metal was used. Microstructures and hardness of the weldments were investigated using optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD) and Vickers microhardness (HV0.5). A ferritescope was also used in the non-destructive evaluation to observe the ferrite content on the weldments. Corrosion behavior of weldments in 1M H2SO4 solution at 25±1°C was investigated using potentiodynamic polarization and immersion tests. Results indicated that the microstructure of fusion zones exhibited dendritic structure contained lathy and skeletal δ-ferrite. The contents of δ-ferrite in the weld zone increased by increasing the number of passes. Therefore, as the number of passes increased, the hardness and corrosion resistance increased.

Modeling of the cadmium transport through a bulk liquid membrane

The model of metal ion permeation through a bulk liquid membrane (BLM), based on the Nernst–Planck equation, was developed. It was satisfactorily tested using the experimental data on the cadmium permeation from Cd(NO3)2 solution through BLM (D2EHPA in kerosene) to 1M H2SO4 solution. According to the model simulations, the cadmium permeation was controlled by Keq on the feed side; the knowledge of the exact Keq value on the strip side under the condition cH2SO4≫cCd was not required. None of the following: an assumed Cd-D2EHPA complex (CdP2(HP)2, CdP2HP), presence of undimerized D2EHPA in BLM, or ion pair formation Cd2+·SO42- in the strip solution, influence the goodness of fit. Assuming the model based on the Fick’s law with the constant cadmium mass transfer coefficient, a large dispersion of its optimal fitting values which depends on the model assumption was found. Thus, that coefficient can only be treated as a fitting parameter.

Effects of Mo additions on the corrosion behavior of WC–TiC–Ni hardmetals in acidic solutions

The corrosion behavior of WC–TiC–Ni cemented carbides with the additions of molybdenum was investigated in 1M H2SO4 and 1M HCl solutions utilizing potentiodynamic polarization, long-term immersion tests and surface analytical techniques. The results show that the Mo additions can enhance the corrosion resistance of WC–TiC–Ni hardmetals owing to the formation of new (Ti, W, Mo)C phase based on TiC. Pseudopassivity was observed in the polarization curves of WC–Ni and WC–TiC–Ni hardmetals in HCl. However, the additions of molybdenum can make WC–TiC–Ni hardmetals passivated visibly in curves at 600mV–1000mV and enhance the pitting corrosion resistance due to the formation of MoO3 film. In addition, all nickel based alloys show the typical passivation behavior in H2SO4 caused by the formation of NiSO4, NiWO4 and continuous metal oxide films.

Electrocatalyst oxidation of formic acid on Pt nanoparticles/Ti electrode

A potent catalyst, platinum nanoparticles (Pt-NPs) supported on titanium substrate (Pt-NPs/Ti), was prepared. The morphology and surface analysis of Pt-NPs/Ti electrodes were investigated using scanning electron microscopy and energy dispersive X-ray spectroscopy respectively. The results indicate that Pt-NPs are homogeneously deposited on the surface of titanium plates. Electrochemical characteristics of formic acid oxidation on Pt-NPs/Ti electrodes were investigated via cyclic voltammetric in mixed 0·1M formic acid and 0·1M H2SO4 solutions. The results were compared to those at a polycrystalline smooth platinum electrode. It was found that the electrocatalytic oxidation of formic acid on the Pt-NPs/Ti electrode increases the rate of formic acid electro-oxidation several times larger than a smooth platinum electrode and confirmed the better electrocatalytic activity and stability of Pt-NPs/Ti electrodes.

Corrosion behaviors of coatings fabricated using bulk metallic glass powders with the composition of Fe68.5C7.1Si3.3B5.5P8.7Cr2.3Mo2.5Al2.0

Two different types of coatings were prepared, by a high velocity oxy-fuel spraying method and a laser spraying method, respectively, using bulk metallic glass powders with the nominal composition of Fe68.5C7.1Si3.3B5.5P8.7Cr2.3Mo2.5Al2.0. The corrosion behaviors of the two coatings in 1M HCl, H2SO4, NaCl and NaOH solutions were investigated based upon the microstructural differences originating from the different coating methods. The amorphous coating layer formed by the high velocity oxy-fuel spraying method exhibited higher, excellent corrosion resistance in the 1M HCl solution. The coating layer formed by the laser spraying method exhibited a high pitting tendency attributed to the dendritic microstructure with various borides and carbides. Due to a great number of pores, the HVOF coating exhibits slightly lower corrosion resistance than the LS coating in alkaline solution.

Tribocorrosion behavior of low temperature plasma carburized stainless steel

Low temperature plasma carburizing is a plasma surface engineering technique developed for austenitic stainless steels to achieve combined improvements in tribological and corrosion resistant properties. However, until recently very little work has been conducted to study the response of carburized stainless steel to combined actions by wear and electrochemical corrosion. In this paper, the tribocorrosion behavior of low temperature plasma carburized AISI 316L stainless steel under unidirectional sliding in 1M H2SO4 and 0.5M NaCl solutions is compared. It is found that in both test solutions, the carburized layer exhibits much better resistance to material removal than the untreated specimen at anodic potentials, but its effectiveness in improving wear resistance at open circuit and cathodic potentials is less significant. Particularly, in the pitting environment containing 0.5M NaCl, numerous corrosion pits are formed inside the wear track on the untreated specimen at potentials much lower than the pitting potential, while no corrosion pits are observed inside the wear track on the carburized specimen at anodic potentials as high as 1000mV(SCE). Further experiments conducted in 1M H2SO4 solution at various contact loads and frequencies reveal that the carburized layer has a much better ability to repassivate than the untreated specimen. The much improved tribocorrosion behavior of the carburized layer can thus be attributed to its high hardness, good corrosion resistance and excellent repassivation ability.

Preparation and electrochemical performances of porous polypyrrole film by interfacial polymerization

AbstractIn this study, porous polypyrrole (PPy) film was synthesized by facile interfacial polymerization using ionic liquid as oxidant. The morphology of PPys changed from dense microspherical/nanospherical agglomerated structure to porous structure with the increasing concentration of the oxidant. The magnetic ionic liquid, 1‐butyl‐3‐methylimidazolium tetrachloroferrate (Bmim[FeCl4]), played a major role of oxidant when the concentration was lower than 0.075M. As the concentration increased to 0.075M, the π–π interactions between pyrrole cations and iminazole ring of Bmim[FeCl4], as evidenced by Fourier transform infrared spectrometer results, may affect the packing of PPy chains and subsequently cause the formation of porous structure of PPys. Electrochemical performances showed that PPy with porous structure displayed the highest specific capacitance of 170 F/g at a current density of 2 A/g in 1M H2SO4 solution and a good capacitive behavior, which has potential application as supercapacitor materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Synthesis and electrochemical properties of hollow polyaniline microspheres by a sulfonated polystyrene template

AbstractHollow polyaniline microspheres (HMsPANI) for supercapacitors were prepared successfully with sulfonated polystyrene microspheres as the template. The prepared electrode materials of HMsPANI consisted of nanoparticles and, thus, had a hierarchical structure. The electrochemical behaviors of the materials were investigated with cyclic voltammetry and galvanostatic charge–discharge tests. A maximum specific capacitance of 421 F/g was achieved in a 1M H2SO4 solution, with the potential ranging from −0.2 to 0.8 V (vs a saturated calomel electrode), in a three‐electrode glass cell at room temperature for the HMsPANI electrode. This suggested its potential application in electrochemical capacitors. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Investigation of the effect of piperidin-1-yl-phosphonic acid on corrosion of iron in sulfuric acid

The inhibitive effect of the piperidin-1-yl-phosphonic acid (PPA) on the corrosion of iron in 1M H2SO4 solution has been investigated by weight loss measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The presence of (PPA) reduces remarkably the corrosion rate of iron in acidic solution. The effect of temperature on the corrosion behavior of iron was studied in the range of 298–328K. Results clearly reveal that the (PPA) behaves as a mixed type corrosion inhibitor with the highest inhibition at 5×10−3M. The adsorption of PPA on the iron surface obeys the Langmuir's adsorption isotherm.

Synthesis, Characterization and Electrochemical Capacitance of Urchin-Like Hierarchical Polyaniline Microspheres

Urchin-like hierarchical polyaniline (PANI) microspheres were synthesized by a simple template-free method. The morphology and structure of the PANI microspheres were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The results indicated that the microspheres had sez-urchin-like architectures with their surfaces consisting of nanofibers with diameters of about 100 nm and length of 2 μm. Cyclic voltammetry and galvanostatic charge/discharge measurements in 1M H2SO4 solution revealed that the microspheres had typical electrochemical supercapacitor behavior but showed lower specific capacitance, due to low conductivity or doping level of the PANI microspheres, in comparison with conventional PANI or PANI nanofibers. The effect of experimental parameters on the morphology and electrochemical properties of PANI microspheres is also discussed.

Corrosion resistance of a new high strength interstitial free steel

Potentiostatic polarisation studies have been carried out on a new high strength copper containing interstitial free steel for automotive applications under various industrially important processing conditions in 0·1M H2SO4 solution at room temperature. It is revealed that corrosion rate in the new steel is lower than that in the conventional mild and high strength interstitial free steels.

Various Temperatures Affecting Characteristics of Pt/C Cathode Catalysts for Polymer Electrolyte Membrane Fuel Cells

This study is aimed to increase the activity of cathodic catalysts for PEMFCs(Polymer Electrolyte Membrane Fuel Cells). we investigated the temperature effect of 20wt% Pt/C catalysts at five different temperatures. The catalysts were synthesized by using chemical reduction method. Before adding the formaldehyde as reducing agent, process was undergone for 2 hours at the room temperature (RT), <TEX>$40^{\circ}C$</TEX>, <TEX>$60^{\circ}C$</TEX>, <TEX>$80^{\circ}C$</TEX> and <TEX>$100^{\circ}C$</TEX>, respectively. The performances of synthesize catalysts are compared. The electrochemical oxygen reduction reaction (ORR) was studied on 20wt% Pt/C catalysts by using a glassy carbon electrode through cyclic voltammetric curves (CV) in a 1M H2SO4 solution. The ORR specific activities of 20wt% Pt/C catalysts increased to give a relative ORR catalytic activity ordering of <TEX>$80^{\circ}C$</TEX> > <TEX>$100^{\circ}C$</TEX> > <TEX>$60^{\circ}C$</TEX> > <TEX>$40^{\circ}C$</TEX> > RT. Electrochemical active surface area (EAS) was calculated with cyclic voltammetry analysis. Prepared Pt/C (at <TEX>$80^{\circ}C$</TEX>, <TEX>$100^{\circ}C$</TEX>) catalysts has higher ESA than other catalysts. Physical characterization was made by using X-ray diffraction (XRD) and transmission electron microscope (TEM). The TEM images of the carbon supported platinum electrocatalysts (<TEX>$80^{\circ}C$</TEX>, <TEX>$100^{\circ}C$</TEX>) showed homogenous particle distribution with particle size of about 2~3.5 nm. We found that a higher reaction temperature resulted in more uniform particle distribution than lower reaction temperature and then the XRD results showed that the crystalline structure of the synthesized catalysts are seen FCC structure.

Corrosion Resistance and Electrical Conductivity of TiN/CrN Multilayer Coated Stainless Steel

In this study, various multilayered TiN/CrN coatings were deposited on the SS316L stainless steel substrates by the cathodic arc deposition technique. By varying the turntable rotation speed, the multilayered coatings with different periodic layer thickness were obtained. The main target of this study is to enhance the corrosion resistance and electrical conductivity of the stainless steel for potential application of metallic bipolar plate of PEMFC. The results showed that all of the TiN/CrN coated samples presented a better corrosion resistance than the bare stainless steel substrate. The multi-layered coatings deposited at the 2 rpm provided the best corrosion resistance of the coated stainless steels when they were subjected to polarization test in 1M H2SO4 solution. The result of single fuel cell test shows that the TiN/CrN multi-layered coating with the best corrosion resistance is considered to be a candidate for PEMFC bipolar plate application in this study.