Effect of corrosion inhibiting compounds on the corrosion behaviour of pure magnesium and the magnesium alloys EV31A, WE43B and ZE41A

This paper studied corrosion of pure Mg and the Mg alloys EV31A,WE43B,ZE41A,coated with commercial corrosion inhibiting compounds(CICs)(LPS 3,LPS2,AMLGuard,Ardrox 3961)immersed in 3.5 wt%(0.6M)Na Cl solution saturated with Mg(OH)_(2).All four CICs reduced corrosion rates.LPS 3 resulted in zero corrosion rates and 100%inhibition in most cases.LPS 2 and AMLGuard had comparable inhibition efficiencies,whilst Ardrox 3961 had the lowest inhibition efficiency.Reduction in corrosion rates was tentatively attributed to barrier films formed by chemical adsorption for LPS 3 and AMLGuard,and by physical adsorption for LPS2 and Ardrox 3961.

Bio-inhibitive effect of an algal symbiotic bacterium on corrosion of magnesium in marine environment

It is a longstanding and challenging task to develop sustainable environment-friendly and cost-effective corrosion-protection technologies for Mg alloys, especially under marine conditions in which corrosion can normally be significantly accelerated by bacterial activity. However,this paper reports on the corrosion of highly active Mg interestingly inhibited by an algal-symbiotic bacterium Bacillus altitudinis. The corrosion of Mg in the presence of the bacterium drastically reduced by one order of magnitude after 14 days of immersion. This means that the algal-symbiotic bacterium widely available in natural ocean environments may be employed as a green and sustainable inhibitor in the marine industry. Based on electrochemical measurements, surface analyses and microbe experiments, a combined inhibition mechanism is proposed in the paper to interpret the interesting corrosion behavior of Mg.

Inhibition mechanism of air nanobubbles on brass corrosion in circulating cooling water systems

Air nanobubbles(A-NBs)were used to inhibit the brass corrosion in circulating cooling water for the first time in the study.The results of mass loss method and electrochemical method showed that A-NBs had the obvious corrosion inhibition effect.The inhibition rate reached 52%at 35℃.The impedance and surface characterization results of corrosion samples indicated that the corrosion inhibition mechanisms of A-NBs mainly included adsorption of corrosion ions,promoting the formation of the passivation film on metal surface and the formation of the bubble layer and scale film on metal surface.A-NBs are potential excellent corrosion inhibitors.

High-temperature corrosion of phosphate completion fluid and corrosion inhibition method by membrane transformation

By analyzing the corrosion of phosphate completion fluid on the P110 steel at 170 °C, the high-temperature corrosion mechanism of phosphate completion fluid was revealed, and a corrosion inhibition method by membrane transformation was proposed and an efficient membrane-forming agent was selected. Scanning electron microscope (SEM) images, X-ray energy spectrum and X-ray diffraction results were used to characterize the microscopic morphology, elemental composition and phase composition of the precipitation membrane on the surface of the test piece. The effect and mechanism of corrosion inhibition by membrane transformation were clarified. The phosphate completion fluid eroded the test piece by high-temperature water vapor and its hydrolyzed products to form a membrane of iron phosphate corrosion product. By changing the corrosion reaction path, the Zn2+ membrane-forming agent could generate KZnPO4 precipitation membrane with high temperature resistance, uniform thickness and tight crystal packing on the surface of the test piece, which could inhibit the corrosion of the test piece, with efficiency up to 69.63%. The Cu2+ membrane-forming agent electrochemically reacted with Fe to precipitate trace elemental Cu on the surface of the test piece, thus forming a protective membrane, which could inhibit metal corrosion, with efficiency up to 96.64%, but the wear resistance was poor. After combining 0.05% Cu2+ and 0.25% Zn2+, a composite protective membrane of KZnPO4 crystal and elemental Cu was formed on the surface of the test piece. The corrosion inhibition efficiency reached 93.03%, which ensured the high corrosion inhibition efficiency and generated a precipitation membrane resistant to temperature and wear.

Effect of water content on corrosion inhibition behavior of self-assembled TDPA on aluminum alloy surface

Self assembled monolayers （SAMs） of 1-tetradecylphosphonic acids （TDPA, CH3（CH2）13P（O）（OH）2 ） were formed on the 2024 aluminum alloy surface in TDPA-containing ethanol-water solutions with different water content. The adsorption and corrosion protection properties of the SAMs for 2024 alloy in 0.1 mol/L H2SO4 solution were examined and characterized by potentiodynamic polarization, electrochemical impedance spectrum （EIS）, Fourier transformed infrared spectroscopy （FTIR）, Auger electron spectra （AES） and atomic force microscopy （AFM）. FTIR and AES results show that the TDPA molecules were successfully adsorbed on the 2024 aluminum alloy surface, and the density of the SAMs increased with the increasing water content in the assembly solution. The results of electrochemical studies and corrosion morphologies observed by AFM show that a 4 h modification resulted in maximal inhibition efficiency, and the higher the water content in the assembly solution is, the better the inhibition performance of the SAMs can be achieved. The effect of water content in TDPA solutions on the performance of the SAMs is related to the hydration reaction of the metal surface.

Corrosion Inhibition of a Green Scale Inhibitor Polyepoxysuccinic Acid

The corrosion inhibition of a green scale inhibitor, polyepoxysuccinic acid (PESA) was studied based on dynamic tests. It is found that when PESA is used alone, it had good corrosion inhibition. So, PESA should be included in the category of corrosion inhibitors. It is not only a kind of green scale inhibitor, but also a green corrosion inhibitor. The synergistic effect between PESA and Zn2+ or sodium gluconate is poor. However, the synergistic effect among PESA, Zn2+ and sodium gluconate is excellent, and the corrosion inhibition efficiency for carbon steel is higher than 99%. Further study of corrosion inhibition mechanism reveals that corrosion inhibition of PESA is not affected by carboxyl group, but by the oxygen atom inserted. The existence of oxygen atom in PESA molecular structure makes it easy to form stable chelate with pentacyclic structure.

Corrosion Inhibition Synergism between Lanthanum(Ⅲ) Ion and 8-Hydroxyquinoline for Zinc in Hydrochloric Acid

The effects of La 3+ ion and chelate reagent 8 hydroxyquinoline on the corrosion rate of zinc in hydrochloric acid were investigated by using weight loss method and electrochemical method. It is found that in a specific concentration range of La 3+ ion and 8 hydroxyquinoline, the obvious corrosion inhibition synergism is obtained. The mechanism of corrosion inhibition synergism was discussed on basis of adsorption theory.

ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY STUDY OF CORROSION INHIBITION OF MODIFIED LIGNOSULPHONATE FOR CARBON STEEL

The corrosion inhibition for carbon steel in circulating cooling water by modified lignosulphonate has been investigated using electrochemical impedance spectroscopy technique. Results show that the inhibition efficiency of modified lignosulphonate GCL2 is a great improvement on that of lignosulphonate. The maximum inhibition efficiency of GCL2 reaches 99.21% at the concentration of 400mg·L^-1 at 303K. The corrosion inhibition of GCL2 is attributed to forming adsorption film on the metal surface for the electrochemical impedance spectroscopy in GCL2 solution shows more than one time-constant.Moreover,results also indicate that it is more efficient in stirring solution than in still solution for GCL2 because the constant of adsorption in stirring solution is much larger than that in still solution. The adsorption of inhibitor GCL2 follows Langmuir＇s adsorption isotherm.

Preparation and characterization of a chitosan-based low-pH-sensitive intelligent corrosion inhibitor

A chitosan （CS）-based low-pH-sensitive intelligent corrosion inhibitor was prepared by loading a pH-sensitive hydrogel with benzotriazole （BTA）; the pH-sensitive hydrogel was synthetized by crosslinking CS with glutaraldehyde （GTA）. Analysis by Fou- tier-transform inflared （FT-IR） spectroscopy showed that Schiff reactions occurred between amino and aldehyde groups. The swelling abil- ity of the hydrogel was investigated using a mass method, and it was observed to swell more in an acidic environment than in an alkaline en- vironment. The hydrogel＇s loading capacity of BTA was approximately 0.377 g·g ^-1, and its release speed was faster in an acidic environment than in an alkaline environment because of its swelling behavior. The corrosion inhibition ability of the intelligent inhibitor was tested by immersion and electrochemical methods. The results showed that after 4 h of immersion, the polarization resistance （Rp） value of copper with the intelligent inhibitor was approximately twice of that of copper with BTA, indicating that the intelligent inhibitor could effectively prevent copper from corroding.

Role of dissolved oxygen reduction in improvement inhibition performance of ascorbic acid during copper corrosion in 0.50 mol/L sulphuric acid

The kinetics of dissolved O_2 reduction and hydrogen evolution reactions on copper surface was studied in naturally aerated and air and O_2-saturated 0.50 mol/L H_2SO_4 solutions using polarization measurements combined with the rotating disc electrode (RDE).The Koutecky-Levich plot indicated that the dissolved O_2 reduction at the copper electrode was an apparent four-electron process.A correlation between the presence of dissolved O_2 and the formation of Cu_2O,confirmed from XRD,was discussed. Ascorbic a...

Mechanism of aluminum corrosion in LiFSI-based electrolyte at elevated temperatures

Lithium bis(fluorosulfonyl)imide(LiFSI) is a promising replacement for lithium hexafluorosphate due to its excellent properties. A solution to the corrosion of aluminum(Al) current collectors by LiFSI at elevated temperatures is essential. The mechanisms of Al corrosion in LiFSI-based electrolyte at 45 ℃ were studied with density functional theory calculations and spectroscopic investigations. It is found that the irregular, loose and unprotected AlF3 materials caused by the dissolution of co-generated Al(FSI)3 can exacerbate Al corrosion with the increase of temperature. Lithium bis(oxalate)borate(LiBOB) can effectively inhibit the Al corrosion with a robust and protective interphase;this can be attributed to the interfacial interactions between the Al foil and electrolyte. Boron-containing compounds promote the change from AlF3 to LiF, which further reinforces interfacial stability. This work allows the design of an interface to Al foil using LiFSI salt in lithium-ion batteries.

A novel green inhibitor for C-steel corrosion in 2.0 mol·L^-1 hydrochloric acid solution

The corrosion inhibition characteristics of aqueous extract of seeds of Melia azedarach L.(MA) have been studied as eco-friendly green inhibitor for corrosion control of C-steel in 2 mol·L^(-1) HCl solution by gravimetric and electrochemical methods. The results depict that, the extract inhibits efficiently the corrosion of carbon steel in hydrochloric acid. The efficiency of extract is increased with increasing the extract concentration but independent on the studied temperature. The adsorption of the extract components onto the steel surface was found to be spontaneous, and follows Langmuir adsorption isotherm. The surface morphology of C-steel, in the absence and presence of MA extract in 2.0 mol·L^(-1) hydrochloric acid solution, was studied using scanning electron microscopy(SEM).

Influence of alkyl group of imidazolinyl-quaternary-ammonium-salt on corrosion inhibition efficiency

The action between imidazolinyl-quaternary-ammonium-salt(IQAS) molecule and Fe atom was studied, and the influence of the alkyl group connected with N atom of imidazoline ring on corrosion inhibition efficiency was explored. Quantum chemical methods, HF/6-31 G and HF/Lan L2 dz, were applied successively to calculate the parameters such as front molecular orbit energy of IQASⅠ-Ⅳ and chemical adsorption for IQASⅠ-Ⅳ and Fe atom. The corrosion inhibition efficiency was measured with the weight loss method of carbon steel samples in acidic solution and oil field sewage. Based on the theoretical analyses and experimental results, it is concluded that N-Fe coordination bond is formed between IQAS molecule and Fe atom, corrosion inhibition efficiency is decreased in the following order(from large to small): IQAS Ⅳ, IQAS Ⅲ, IQAS Ⅱ, IQASⅠ.

Corrosion inhibition of layered double hydroxides for metal-based systems

Layered double hydroxide(LDH),a kind of 2D layered materials,has been recognized as the promising anticorrosion materials for metal and its alloy.The microstructure,physical/chemical properties,usage in corrosion inhibition and inhibition performance of LDH have been studied separately in open literature.However,there is a lack of a complete review to summarize the status of LDH technology and the potential R&D opportunities in the field of corrosion inhibition.In addition,the challenges for LDH in corrosion inhibition of metal-based system have not been summarized systematically.Herein,we review recent advances in the rational design of LDH for corrosion inhibition of metal-based system(i.e.Mg alloy,Al alloy,steel and concrete)and high-throughput anticorrosion materials development.By evaluating the physical/chemical properties,usage in metal-based system and the corrosion inhibition mechanism of LDH,we highlight several important factors of LDH for anticorrosion performance and common features of LDH in applying different metal alloys.Finally,we provide our perspective and recommendation in this field,including high-throughput techiniques for combinatorial compositional design and rapid synthesis of anticorrosion alloys,with the goal of accelerating the development and application of LDH in corrosion inhibition of metal-based system.

2,3,5-Triphenyl-2H-tetrazolium Chloride and 2,4,6-Tri（2-pyridyl）-s-triazine on the Corrosion of Mild Steel in HCl

Electrochemical measurement, quantum chemical method, and scanning electron microscopy （SEM） were performed to investigate the inhibitive effect of 2,3,5-triphenyl-2H-tetrazolium chloride （TTC） and 2,4,6-tri（2-pyridyl） -s-triazine（TPT） on the corrosion of mild steel in lmol.L^-1 HCl at room temperature. Impedance spectroscopy measurement showed that the polarization resistance increased and that double layer capacitance decreased with the increase in the inhibitive concentration, and the results of potentiodynamic polarization showed that the inhibitors suppressed both cathodic and anodic processes of steel corrosion without change in the mecha-nism. Higher the orbital density distribution strength of the lowest unoccupied molecular orbital, higher is the molecule dipole, and lower energy gap between the energy of the highest occupied molecular orbital and the energy of the lowest unoccupied molecular orbital resulted in higher inhibitory efficiency. The results of SEM analysis showed that the metal-was protected from aggressive corrosion by the addition of TTC and TPT.

Corrosion Inhibition of Carbon Steel in Hot Hydrochloric Acid Solutions

The dissolution of carbon steel in 5% HCl in the temperature range of 30~90℃ was inhibited by two organic compounds having the general formula: ClR NH2(CH2)n NH2 RCl where R is a benzyl group. The behaviour of these inhibitors in acidic medium were investigated using weight loss method, open circuit potential and linear polarization technique. These inhibitors provided satisfactory corrosion inhibition for carbon steel in hydrochloric acid solutions even at higher temperature and acid concentration (10%). The electrochemical results showed that the polarization resistance (Rp) values increased with increasing inhibitor concentration, also the corrosion current decreased and a higher inhibition efficiency was obtained. The protective properties of these two organic inhibitors were attributed to the chemisorption mechanism

Effects of different simulated fluids on anticorrosion biometallic materials

The corrosion behaviors of SUS316L stainless steel, Co Cr alloy and Ti 6Al 4V alloy in Ringer’s, PBS(-) and Hank’s solutions have been investigated. The results indicate that the corrosion of Ringer’s solution is the strongest, then followed by PBS(-) and Hank’s solution. The presence of HPO 2- 4, H 2PO - 4, SO 2- 4 and glucose in the PBS(-)and Hank’s solution probably reduces the corrosion inhibitor and corrosion current. The decrease of the solution’s pH significantly increases the corrosion rate and susceptibility to localized corrosion of SUS316L SS and Co Cr alloy. However, Ti 6Al 4V alloy exhibits an exceptional stability and has only a slight increase of corrosion rate with decreasing pH.

Synergistic inhibition effect of poly(ethylene glycol) and cetyltrimethylammonium bromide on corrosion of Zn and Zn-Ni alloys for alkaline batteries

The synergistic inhibition effect of poly(ethylene glycol)-400(PEG-400)and cetyltrimethylammonium bromide(CTMAB)on the corrosion of Zn and Zn-Ni alloys in 8 mol/L KOH solution saturated with Zn O was observed by potentiodynamic anodic/cathodic polarization(PDP),and electrochemical impedance spectroscopy(EIS)measurements.The electrochemical studies confirmed that there was a synergism between PEG-400 and CTMAB on corrosion inhibition of Zn and its alloys.Corrosion inhibition efficiency of the mixed inhibitors,250 mg/L CTMAB+250 mg/L PEG-400,was found to be much higher than that of the single inhibitor,500 mg/L PEG-400 or 500 mg/L CTMAB.Scanning electron microscopic(SEM)investigations before and after the corrosion inhibition process emphasize the synergistic effect of the mixed inhibitors.Accordingly,it was found that the addition of the investigated inhibitors to the alkaline solution enhanced the discharge and capacity of the alkaline battery anodes.The obtained electrochemical data exhibited a good correlation with the computational one.

Synergic Mechanism of an Organic Corrosion Inhibitor for Preventing Carbon Steel Corrosion in Chloride Solution

The inhibition effect of dimethylethanolamine（DMEA） and its composite with carboxylic acid was studied with the electrochemical tests. The experimental results indicate that DMEA is not a good inhibitor but the composite of DMEA with caprylic acid exhibits excellent inhibiting efficiency. The synergic mechanism of the organic corrosion inhibitors（OCIs） was studied with quantum chemical calculations. It is found that the DMEA forms a quaternary ammonium salt with the proton in carboxylic acid, and a cyclic complex formed between the salt and Fe may be responsible for the enhancement of inhibiting efficiency. The possible hydrogen bond formed between DMEA and carboxylic acid is not enough for the inhibiting effect. This work is helpful to proposing theoretical interpretation as well as developing a functional organic inhibitor to improve the durability of reinforced concrete contaminated with chloride.

Laccase Immobilized on Mesoporous Silica Materials and Its Corrosion Inhibition Performance in Circulating Cooling Water System

Mesoporous SiO_2 microspheres were synthesized using the sol-gel method and were characterized by TEM, FT-IR and BET techniques. The diameter of the microspheres is about 100—150 nm, and the average mesopore diameter is 2.55 nm, while the specific surface area is 1 088.9 m2/g. Mesoporous SiO_2 microspheres adsorb glutaraldehyde and immobilize laccase by means of the aldehyde group in glutaral which can react with the amidogen of laccase. The immobilization conditions were optimized at a glutaraldehyde concentration of 0.75%, a crosslinking time of 8 h, a laccase concentration of 0.04 L/L and an immobilization time of 10 h. When diesel leakage concentration was 80 mg/L, the highest corrosion inhibition efficiency of immobilized laccase reached 49.23%, which was slightly lower than the corrosion inhibition efficiency of free laccase(59%). The diesel degradation ratio could reach up to 45%. It has been proved that the immobilized laccase could degrade diesel to inhibit corrosion.