Ambrish Singh

Aqueous Extract of Kalmegh (Andrographis paniculata) Leaves as Green Inhibitor for Mild Steel in Hydrochloric Acid Solution

The inhibition of the corrosion of mild steel in hydrochloric acid solution by the extract of Kalmegh (Andrographis paniculata) leaves extract has been studied using weight loss, electrochemical impedance spectroscopy, linear polarization, and potentiodynamic polarization techniques. Inhibition was found to increase with increasing concentration of the extract. The effect of temperature, immersion time, and acid concentration on the corrosion behavior of mild steel in 1 M HCl with addition of extract was also studied. The inhibition was assumed to occur via adsorption of the inhibitor molecules on the metal surface. The adsorption of the molecules of the extract on the mild steel surface obeyed the Langmuir adsorption isotherm. The protective film formed on the metal surface was analyzed by FTIR spectroscopy. The results obtained showed that the extract of Kalmegh (Andrographis paniculata) leaves extract could serve as an effective inhibitor of the corrosion of mild steel in hydrochloric acid media.

Corrosion Inhibition of Carbon Steel in HCl Solution by Some Plant Extracts

The strict environmental legislations and increasing ecological awareness among scientists have led to the development of “green” alternatives to mitigate corrosion. In the present work, literature on green corrosion inhibitors has been reviewed, and the salient features of our work on green corrosion inhibitors have been highlighted. Among the studied leaves, extract Andrographis paniculata showed better inhibition performance (98%) than the other leaves extract. Strychnos nuxvomica showed better inhibition (98%) than the other seed extracts. Moringa oleifera is reflected as a good corrosion inhibitor of mild steel in 1 M HCl with 98% inhibition efficiency among the studied fruits extract. Bacopa monnieri showed its maximum inhibition performance to be 95% at 600 ppm among the investigated stem extracts. All the reported plant extracts were found to inhibit the corrosion of mild steel in acid media.

Corrosion inhibition of N80 steel in 15% HCl by pyrazolone derivatives: electrochemical, surface and quantum chemical studies

The corrosion protection of N80 steel in 15% HCl by two pyrazolone derivatives namely 2-(3-amino-5-oxo-4,5-dihydro-1H-pyrazol-1-yl)(p-tolyl)methyl)malononitrile (PZ-1) and 2-((3-amino-5-oxo-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methyl)malononitrile (PZ-2) has been investigated by using gravimetric, electrochemical and quantum chemical studies. The observed results reveal that PZ-1 is a better inhibitor than PZ-2. Tafel polarization showed that PZs are mixed type inhibitors but dominantly affect the cathodic reaction. Both inhibitors were found to obey the Langmuir adsorption isotherm. Scanning electron microscopy (SEM) and scanning electrochemical microscopy (SECM) images support the protection of the N80 steel in the presence of the PZs. Quantum chemical study reveals that both inhibitors have a tendency to get protonated and this result supports the experimental observations.

Porphyrins as Corrosion Inhibitors for N80 Steel in 3.5% NaCl Solution: Electrochemical, Quantum Chemical, QSAR and Monte Carlo Simulations Studies

The inhibition of the corrosion of N80 steel in 3.5 wt. % NaCl solution saturated with CO2 by four porphyrins, namely 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphyrin (HPTB), 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphyrin (T4PP), 4,4′,4″,4‴-(porphyrin-5,10,15,20-tetrayl)tetrakis(benzoic acid) (THP) and 5,10,15,20-tetraphenyl-21H,23H-porphyrin (TPP) was studied using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electrochemical microscopy (SECM) and scanning electron microscopy (SEM) techniques. The results showed that the inhibition efficiency, η% increases with increasing concentration of the inhibitors. The EIS results revealed that the N80 steel surface with adsorbed porphyrins exhibited non-ideal capacitive behaviour with reduced charge transfer activity. Potentiodynamic polarization measurements indicated that the studied porphyrins acted as mixed type inhibitors. The SECM results confirmed the adsorption of the porphyrins on N80 steel thereby forming a relatively insulated surface. The SEM also confirmed the formation of protective films of the porphyrins on N80 steel surface thereby protecting the surface from direct acid attack. Quantum chemical calculations, quantitative structure activity relationship (QSAR) were also carried out on the studied porphyrins and the results showed that the corrosion inhibition performances of the porphyrins could be related to their EHOMO, ELUMO, ω, and μ values. Monte Carlo simulation studies showed that THP has the highest adsorption energy, while T4PP has the least adsorption energy in agreement with the values of σ from quantum chemical calculations.

The extract of Jamun (Syzygiumcumini) seed as green corrosion inhibitor for acid media

The corrosion inhibition of mild steel in hydrochloric acid and sulfuric acid solutions by the extract of Syzygium cumini seed was studied using chemical, electrochemical impedance spectroscopy, linear polarization, and potentiodynamic polarization techniques. The inhibition was assumed to occur via adsorption of the inhibitor molecules on the metal surface. The adsorption of the extract on the mild steel surface obeyed Langmuir’s isotherm. The results obtained showed that the extract of S. cumini could act as an effective inhibitor of the corrosion of mild steel in hydrochloric and sulfuric acid media.

THE EFFECT OF ENVIRONMENTALLY BENIGN FRUIT EXTRACT OF SHAHJAN (MORINGA OLEIFERA) ON THE CORROSION OF MILD STEEL IN HYDROCHLORIC ACID SOLUTION

The inhibition of the corrosion of mild steel in hydrochloric acid solution by the fruit extract of shahjan (Moringa oleifera) was studied using weight loss, electrochemical impedance spectroscopy (EIS), linear polarization, and potentiodynamic polarization techniques (Tafel). Inhibition was found to increase with increasing concentration of the extract. The effect of temperature, immersion time, and acid concentration on the corrosion behavior of mild steel in hydrochloric acid solutions with addition of extract was also studied. The inhibition occurred via adsorption of the inhibitor molecules on the mild steel surface obeying the Langmuir adsorption isotherm. Thermodynamic activation parameters such as activation energy, enthalpy (ΔH*), and entropy (ΔS*) of activation for corrosion process were calculated and discussed. The results obtained show that both chemical and physical adsorption of inhibitor molecules occur simultaneously and the fruit extract of shahjan (Moringa oleifera) could serve as an effective inhibitor of the corrosion of mild steel in hydrochloric acid media.

Some Pyrimidine Derivatives as Corrosion Inhibitor for Mild Steel in Hydrochloric Acid

The inhibition effect of four pyrimidine derivatives (PPDs) on the corrosion of mild steel in hydrochloric acid medium has been investigated using gravimetric measurements, electrochemical impedance spectroscopy, potentiodynamic polarization, and energy dispersive x-ray spectroscopy (EDX) techniques. Electrochemical impedance spectroscopy (EIS) data showed that the addition of PPDs increases the charge-transfer resistance (Rct) and decreases the double-layer capacitance (Cdl). Potentiodynamic polarization revealed that PPDs acted as mixed-type inhibitors but are predominantly cathodic. The adsorption of studied compounds obeyed the Langmuirs adsorption isotherm. EDX and quantum chemical calculations support the experimental results. GRAPHICAL ABSTRACT

Effect of Different Heat Treatments on Microstructure and Mechanical Properties of Ti6Al4V Titanium Alloy

Abstract This paper analyzed the microstructure of Ti6Al4V titanium alloy after different heat treatments. The tensile experiment and instrumented impact test were performed. The relationship among the microstructure, impact fracture characteristic and mechanical properties was analyzed by metallurgical microscope and environment scanning electron microscope (ESEM). Results show that the microstructure, mechanical properties and impact toughness of Ti6Al4V titanium alloy are affected by the solution and aging treatment. The yield strength and ultimate tensile strength are improved remarkably. The ductility increases firstly, and then decrease. The good comprehensive properties can be obtained when the Ti6Al4V titanium alloy is treated under the condition of 960 °C/1 h + WQ and 500 °C/4 h + AC. σ0.2 is 1050 MPa, σb is 1120 MPa and Ak is 46.22 J·cm−2. The microstructure of the titanium alloy after solution and aging treatment consists of the β matrix and the precipitation of the α-phase. The lamellar β-phase and the α-phase structure of the small needle plexiform can enhance comprehensive properties.

Chromenopyridin derivatives as environmentally benign corrosion inhibitors for N80 steel in 15% HCl

Abstract This research work was to investigate the corrosion inhibition performance of two newly synthesized chromenopyridine derivatives namely 2,4-diamino-5-(phenylthio)-5H-chromeno[2,3-b]pyridine-3-carbonitrile (PPC-1) and 2,4-diamino-5-phenoxy-5H-chromeno[2,3-b]pyridine-3-carbonitrile (PPC-2) as potential environmentally friendly corrosion inhibitors for N80 steel in 15% hydrochloric acid (HCl). Various techniques like gravimetric, electrochemical impedance spectroscopy (EIS), Tafel polarizations, scanning electron microscope (SEM) and atomic force microscopy (AFM) have been used. The inhibition efficiencies given by PPC-1 and PPC-2 at 200 mg L–1 are 92.4% and 82.1% respectively. Tafel polarization revealed that both inhibitors are cathodic in nature. Langmuir adsorption isotherm was found to be the best fit. The experimental result was further supported by quantum chemical study.

Use of HPHT autoclave to determine corrosion inhibition effect of poly(methyl methacrylate-co-N-vinyl-2-pyrrolidone) on carbon steels in 3.5% NaCl solution saturated with CO2

The influence of poly(methylmethacrylate-co-N-vinyl-2-pyrrolidone), P(MMA-co-VP), on corrosion of carbon steels (J55, N80, P110SS and C110 steels) in 3.5 wt% NaCl solution saturated with CO2 was evaluated using static high pressure and high temperature (HPHT) autoclave. The surface was further evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and contact angle measurements. Quantum chemical calculations have been used to evaluate the structural, electronic and reactivity parameters of the inhibitor on the steels surface. SEM, XRD and contact angle measurement studies reveal that the surface of metals are quite unaffected after use of inhibitor in 3.5% NaCl solution saturated with CO2.