Corrosion inhibition of gatifloxacin on mild steel in 3% HCL solution北大核心CSCD

The inhibition effect of gatifloxacin on the corrosion of mild steel in 3%HCl solution was investigated by means of mass loss measurements and electrochemical measurements. The surface morphology of the steel after corrosion was studied by scanning electron microscope (SEM). The results demonstrated that the highest inhibition efficiency of gatifloxacin reached 95.6% for a dose of gatifloxacin 700 mg/L. Gatifloxacin acted as a mixed-type inhibitor, the cathodic and anodic processes of corrosion were suppressed. Thermodynamic parameters were acquired from data of weight loss at different experimental temperatures, which suggested that the adsorption of gatifloxacin on metal surface obeyed Langmuir adsorption isotherm model. The adsorption processes were exothermic, and belong to chemisorption and physisorption. The entropy of adsorption processes increased. © 2016, Corrosion Science and Protection Technology. All rights reserved.     

Corrosion protection studies of CeO2–TiO2 nanocomposite coatings on mild steel

Nanocomposite coatings have evolved as corrosion-resistant materials to protect metals and alloys in various environments. The need for development of corrosion-resistant materials for mild steel in marine environment is still in demand. The CeO₂–TiO₂ nanocomposite powders were produced via hydrothermal synthesis and the corrosion resistance behaviour of the nanocomposite coatings were evaluated in 3.5% NaCl solution using Tafel polarisation and electrochemical impedance spectroscopy techniques. The trends of open-circuit potential curves provided clear evidence that the incorporation of CeO₂ in TiO₂ nanostructures is beneficial, as it introduces potential shift towards noble positive potential for nanocomposite coatings. Also, the corrosion resistance was enhanced with increase in the CeO₂ content in TiO₂ nanocomposite coatings. Almost 22 times decrease in the corrosion current densities of mild steel were attained for 15?wt-% CeO₂–TiO₂, which demonstrated the advantage of CeO₂–TiO₂ nanocomposite coatings for corrosion protection of mild steel.     

Corrosion properties of anodic oxide coatings on Ti–6Al–4V in simulated body solution

Abstract

Anodic oxide coatings were synthesised on Ti–6Al–4V substrates using aqueous electrolytes containing dissolved calcium and phosphorus. Different coatings were produced by varying the time of synthesis. Inherent features of the coatings were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Uniform corrosion, electrochemical polarisation and ac impedance tests were performed in simulated body fluid (SBF). Small amounts of calcium and phosphorus are deposited from the electrolyte on to the coating and their levels increase with increasing duration of synthesis. Maximum values of porosity and thickness are obtained for oxides coated for 3 h. Coatings produced from shorter times showed very good resistance to the attack of SBF.     

Electrochemical behavior of organic and inorganic zinc-rich coatings in 3.5% NaCl solution

1　INTRODUCTIONZinc richcoatings (ZRP)havebeenusedformanyyearsinordertoprotectsteeleffectivelyinag gressiveatmospheres ,mainlyinmarineandindustrialenvironments,againstcorrosion .ItiscommonlyacceptedthattwofundamentalprotectionmechanismsoperateinZRP[13] :1)thegalvanicprotectionstage ,whichrequires goodelectricalcontactamongthezincparticlesthemselvesaswellasbetweenthemandthesteelsubstrate ;2 )thebarrier likebehaviorstage ,whichisreinforcedbytheamountandnatureofzinccorrosionproductslead ing…     

Corrosion resistance of Ti–6Al–4V alloy with nitride coatings in Ringer’s solution

The corrosion behaviour of Ti–6Al–4V alloy with nitride coatings was investigated in Ringer’s solution at 36 and 40 °С. Nitride coatings of different composition, thickness and surface quality were formed because of changing nitrogen partial pressure from 1 to 10⁵ Ра and nitriding temperature from 850 to 900 °С. Results shown that nitride coatings improve anticorrosion properties of alloy at both solution temperatures. Corrosion resistance of alloy increases with the content increase of TiN phase in nitride coating. With increase of temperature from 36 to 40 °С the corrosion resistance of alloy is determined significantly by quality of nitride coating.     

Corrosion resistance of calcium-modified zinc phosphate conversion coatings on magnesium–aluminium alloys

The influence of the microstructure of the calcium-modified zinc phosphate (Zn–Ca–P) conversion coatings of Mg–Al alloys on corrosion resistance was investigated using OM and SEM and hydrogen evolution tests. The results demonstrated that the Zn–Ca–P coatings markedly enhanced the corrosion resistance of the alloys. The microstructure and chemical compositions of the alloys exerted a significant influence on the corrosion resistance of their coatings. A model was proposed to elucidate the formation mechanism of the porous Zn–Ca–P coating on the AM30 alloy.     

Incorporation graphene into sprayed epoxy–polyamide coating on carbon steel: corrosion resistance properties

In this study, the graphene incorporated into epoxy–polyamide coatings were successfully obtained on carbon steel substrates by spraying process. The corrosion resistance properties of the coatings were investigated, including salt spray corrosion, sea water corrosion and electrochemical corrosion resistance. The results show that the addition of graphene could improve the corrosion resistance properties of the epoxy–polyamide coatings. The coatings in the presence of graphene had better salt spray corrosion than that in the absence of graphene. The surface of the epoxy–polyamide coating exhibited lots of pitting corrosion. The coatings with the addition of graphene showed better sea water corrosion than the coating without graphene. After drying, the epoxy–polyamide coating in the absence of graphene was broken and failed. The coating with 1?wt-% graphene exhibited the best anticorrosion capability as evidenced by the highest corrosion potential and the lowest corrosion current density. The graphene incorporated into epoxy–polyamide coatings were shown to effectively protect carbon steel against corrosion because the graphene nanosheets could be acted as the good chloride ions, oxygen and water molecules barrier.     

Anisotropic mechanical properties of polymorphic hybrid inorganic–organic framework materials with different dimensionalities

Hybrid inorganic–organic framework materials have recently developed into an important new class of solid-state materials. Their mechanical properties are as yet unexplored, although they could be of great utility in view of their enormous structural and chemical diversity. The anisotropic mechanical properties of two new copper phosphonoacetate polymorphs, one a three-dimensional coordination polymer and the other a layered material with inter-layer hydrogen bonding, have been studied by nanoindentation with single crystals. The elastic and plastic anisotropy, the onset of plasticity and the fracture toughness anisotropy have been investigated along the main crystallographic directions. The anisotropy of the mechanical properties can be correlated directly with the underlying crystalline structures. For example, the elastic modulus is largest (up to ～90 GPa) along directions that are dominated by inorganic chains or sheets and smallest (～35 GPa) along directions where the organic ligands provide the primary linkages. This study also highlights the capabilities and limitations of nanoindentation for studying the anisotropic mechanical properties of hybrid framework materials.     

Fabrication and anticorrosion performance of Ni–P–BN nanocomposite coatings on mild steel

Ni–P–BN composite coatings were successfully obtained on low carbon steel by the electroless plating technique. Deposits were characterized by the X-ray diffraction, scanning electron microscopy, and energy-dispersive analysis. The hardness and microstructure of as plated and heat treated Ni–P and Ni–P–BN composites were analyzed. Change in microstructure and higher hardness was noticed for the heattreated composite. The corrosion resistance of as plated and heat treated Ni–P and Ni–P–BN coatings was investigated by the Tafel plots and electrochemical impedance spectroscopy studies in 3.5 wt % NaCl. The heat-treated composite coatings exhibited enhanced corrosion resistance over that of Ni–P coatings.     

Electrodeposition of multi-layer Pd–Ni coatings on 316L stainless steel and their corrosion resistance in hot sulfuric acid solution

Pd–Ni coating shows good corrosion resistance in strong corrosion environments. However, in complex aggressive environments, the performance of the coatings is limited and further improvement is necessary. The effects of the applied plating current density on the composition, structure and properties of Pd–Ni coatings were studied. By changing the current density in the same bath, multi-layer Pd–Ni coatings were prepared on 316L stainless steel. Scanning electronic microscopy, weight loss tests, adhesion strength, porosity and electrochemical methods were used to study the corrosion resistance of the films prepared by different coating methods. Compared with the single layer Pd–Ni coating, the multi-layer coatings showed higher microhardness, lower internal stress, lower porosity and higher adhesive strength. The multi-layer Pd–Ni coating showed obviously better corrosion resistance in hot sulfuric acid solution containing Cl^?.     

Effect of the temperature of cerium nitrate–NaCl solution on corrosion inhibition of mild steel

In this study, the effect of temperature on corrosion inhibition is studied in the absence and presence of an optimal concentration of cerium nitrate (600 mg/L) as an inhibitor of mild steel in sodium chloride. Corrosion tests are carried out through electrochemical techniques such as impedance spectroscopy and d.c. polarization measurements. The surface morphology of the films is investigated by optical microscopy, white-light interferometry, and scanning electronic microscopy, coupled with energy-dispersive spectroscopy analysis for chemical composition. The results obtained show that the activation energy for the corrosion inhibition process to occur increases in the presence of a cerium nitrate inhibitor. However, the corrosion resistance of mild steel is somewhat lost upon increasing the solution temperature up to 55°C, which leads to more cracked films. The enthalpy and entropy values suggest a mixed mechanism of chemisorption and physisorption inhibition, with a major dominance of physisorption control.     

A study of zinc phosphate coatings on 12·5Cr–21·0Ni stainless steel

Abstract

12·5Cr–21·0Ni stainless steel was chemically treated with zinc phosphate in order to find the most suitable phosphate solution and its operating parameters. The phosphate coatings were tested for their corrosion protection of stainless steel using three methods: the salt spray test, the humidity cabinet test and the brine immersion test. The phosphate coatings were also mechanically tested using a tensile test for determining their mechanical properties. Results clearly show that phosphate coatings with a uniform appearance and full coverage can give high corrosion protection to 12·5Cr–21·0Ni stainless steel by forming a physical barrier against the corrosive environment. The 12·5Cr–21·0Ni stainless steel after coating with zinc phosphate still retains reliable mechanical properties, thereby providing valuable applications in the engineering field.     

Post-weld heat treatment influence on galvanic corrosion of GTAW of 17-4PH stainless steel in 3·5%NaCl

Abstract

The influence of post-weld heat treatment (PWHT), solution annealing followed by aging at 480, 550 and 620°C on the galvanic corrosion in 17-4PH stainless steel weldment in 3·5%NaCl was studied. Potentiodynamic polarisation revealed that all PWHTs improve the passivity of weld region by increasing the pitting potential. Heat affected zone disappears, and base and weld regions act as the anode and the cathode respectively. Zero resistance ammetry measurement for 42 h showed that PWHTs improve the galvanic corrosion resistance by decreasing the galvanic current density to a few to tenths of nanoampere per square centimetre. Aging at 620°C has the highest risk of galvanic corrosion among the three PWHTs. Difference in corrosion characteristic of base and weld were addressed to microstructure variations including ferrite, copper rich precipitates and reverted austenite.     

Fabrication of hydrophobic and antireflective coatings based on hybrid silica films by sol–gel process

This paper reports the synthesis of hydrophobic and antireflective coatings by sol–gel process at room temperature (25 °C), using tetraethylorthosilicate (TEOS) as a precursor and methyltriethoxysilane (MTES), phenyltriethoxysilane (PTES), vinyltriethoxysilane (VTES), and octyltriethoxysilane (OTES) as surface modifying agents. The silica sol was prepared by keeping the molar ratio of TEOS:RTES at 1:1, in acidic conditions with ethanol and 0.1 M HCl. All hybrid systems were enriched with titanium(IV) isopropoxide as the cross-linking agent. It was observed that the obtained silica films become hydrophobic with the introduction of the hydrophobic organic group. The higher value of static water contact angle (107 ± 3°) was obtained for the silica film prepared with TEOS + OTES. Under optimal synthesis condition, we obtained antireflection coatings, exhibiting a low reflection in the visible range.     

Investigation of adsorption and corrosion inhibition effect of 1,1’-thiocarbonyldiimidazole on mild steel in hydrochloric acid solution

The adsorption and inhibition effect of 1,1′-thiocarbonyldiimidazole (TCDI) on the corrosion of mild steel (MS) in 0.5 M HCl solution was studied in both short and long immersion time (120 h) with the help of electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques. For long-time tests, the hydrogen gas evolution (VH₂-t) and the change of open circuit potential with immersion time (E _ocp-t) were also utilized in addition to the former two techniques. The surface morphology of MS after its exposure to 0.5 M HCl solution with and without 1.0 × 10⁻² M TCDI was examined by scanning electron microscopy (SEM). It was demonstrated that the inhibition efficiency of studied inhibitor is concentration depended and increased with TCDI concentration. The higher value of inhibition efficiency was obtained after longer immersion time merely on the basis of strong increase of corrosion rate of mild steel in the blank solution. The high inhibition efficiency was discussed in terms of adsorption of inhibitor molecules and protective film formation on the mild steel surface which was substantiated by SEM micrographs. The adsorption of TCDI on MS was found to obey Langmuir adsorption isotherm.     

Cyclic oxidation resistance of Ni–Al alloy coatings deposited on steel by a cathodic arc plasma process

The cyclic oxidation resistance of nickel-aluminide coatings deposited on steel using a cathodic arc plasma (CAP) process has been investigated. Our results show that nickel-aluminide films can be successfully deposited on carbon steel and stainless steel substrates by this process; NiAl₃ is the major phase in the deposited films. The thermal cycling behaviour suggests that such coatings can resist oxidation through physical blocking of oxygen, either by the coating itself or by the aluminium oxide scale subsequently formed in-service. Aluminium diffusion inwards to the substrate may also be beneficial to the thermal oxidation resistance. The coating protects stainless steel substrate materials at 500°C by transforming the NiAl₃ phase into NiAl, producing aluminium oxide on the open substrate surface. At 800°C, oxide flaking is suppressed by the trace amounts of nickel or aluminium which have partially diffused into the substrate.     

Corrosion inhibition of carbon steel in diethanolamine–H2O–CO2 system by some organic sulphur compounds

ABSTRACT

This paper presents an electrochemical investigation of the corrosion inhibition of carbon steel in diethanolamine–water–carbon dioxide systems by four sulphur-containing organic compounds: 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, diethyl thiourea and dimethyl sulfoxide which were found to be effective in the same order as introduced. Potentiodynamic polarisation revealed their cathodic mechanism of action. The adsorption–desorption behaviour of the inhibitors was studied using capacitance-potential and the constant phase element exponent-potential profiles obtained from dynamic electrochemical impedance spectroscopy measurements. Furthermore, quantum chemical calculations at the density functional theory level were performed to help in the analysis of the experimental results. The inhibition power of mercaptobenzazoles was found regardless to whether they were dissociated or not. The double layer capacitance values showed a rather consistent increasing trend with some theoretical parameters namely, the fraction of transferred electrons, the highest occupied molecular orbital energy level, and the permanent dipole moments of the inhibitor molecules.     

Study of pitting corrosion on mild steel during wet–dry cycles by electrochemical noise analysis based on chaos theory

Electrochemical noise (EN) was used to investigate the corrosion behaviour of mild steel (Q235) in 0.1 M Na₂SO₄ and 0.1 M NaCl aqueous solutions during wet–dry cycles. The positive fraction and value of the Largest Lyapunov Exponent (LLE) of electrochemical current noise (ECN) were found out to represent the number and isolation degree of the pits formed in two electrolyte conditions. The calculated results indicate that metastable pits are more plentiful and uniformly distributed in wet cycles and in Na₂SO₄ solution than those in dry cycles and in NaCl solution respectively.     

Corrosion fatigue behavior of epoxy-coated Mg–3Al–1Zn alloy in NaCl solution

The corrosion fatigue behavior of epoxy-coated Mg–3Al–1Zn alloy was investigated in air and 3.5 wt%NaCl solution. Epoxy coating as a new method was used to improve the corrosion fatigue property of the material.Results show that the fatigue limit(FL) of the coated specimens is higher than that of the uncoated specimens in3.5 wt% NaCl solution because of the strengthening and blocking functions of the epoxy coating. The FL of the coated specimens in 3.5 wt% NaCl solution is as high as that in air. It implies that the coated specimens are not as sensitive to the environment as the magnesium alloy. The low tensile strength and the short elongation of the pure epoxy coating lead to that the fatigue crack of the coated specimen is always initiated from the epoxy-coating film Pores and pinholes accelerate the fatigue crack initiation process. Pinholes are caused by the corrosion reactions between the epoxy coating and the NaCl solution.