Effects of SO42− concentration on corrosion behaviour of carbon steels

2015 ◽  
Vol 62 (5) ◽  
pp. 322-326 ◽  
Author(s):  
Zhiping Zhu ◽  
Xiaocui Jiao ◽  
Xueying Tang ◽  
Haiwei Lu
Keyword(s):  
Water Chemistry ◽  
Pitting Corrosion ◽  
Design Methodology ◽  
Competitive Adsorption ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Carbon Steels ◽  
Boiler Water ◽  
Content Type ◽  
Condition Solution

Purpose – The purpose of this paper was to investigate the effects of SO42− concentration on the corrosion behaviour of T23 and T12 steels in simulated water chemistry condition solution of 600 MW fossil-fired power boilers. Design/methodology/approach – The influence and mechanism of SO42− ions on the pitting corrosion of T23 and T12 steels in simulated oxygenated treatment water chemistry solution was studied using electrochemical potentiodynamic polarization scans and electrochemical impedance spectroscopy. Findings – The results showed that T23 and T12 were susceptible to pitting corrosion in the simulated solution with full SO42− concentration for the competitive adsorption of OH− and SO42− on the surface of steels. The pitting sensitivity of the steels improved with increasing SO42− concentration. The corrosion resistance for SO42− of T23 was stronger than that for T12. Originality/value – This study is an attempt to provide direction for regulating the concentration of SO42− in boiler water and for selecting the material for boiler water wall tubes.

Effect of carbides on sensitivity of pitting corrosion in Inconel 718 alloy

2020 ◽  
Vol 67 (2) ◽  
pp. 158-165
Author(s):  
Xianping Wei ◽  
Wen Jie Zheng
Keyword(s):  
Pitting Corrosion ◽  
Inconel 718 ◽  
Design Methodology ◽  
Electrochemical Impedance ◽  
Immersion Test ◽  
Nacl Solution ◽  
Inconel 718 Alloy ◽  
Content Type ◽  
Corrosion Susceptibility ◽  
Dynamic Electrochemical Impedance Spectroscopy

Purpose This paper aims to expand the application area of Inconel 718 alloy in marine environment, the sensitivity of pitting corrosion should be analyzed and discussed, especially the effect of block carbides. Design/methodology/approach Effect of carbides on the sensitivity of pitting corrosion for Inconel 718 alloy was carried out at 30°C in 3.5% NaCl solution using dynamic electrochemical impedance spectroscopy and anodic polarization techniques. In addition, the initiation of pitting corrosion was investigated by immersion test in 0.05 M HCl + 6% FeCl3 solution. Findings As a result, the precipitation of carbides, as the initiation of pitting corrosion, increased pitting corrosion susceptibility, especially the block carbides could lead to deep-spalling. Within that process, temperature and potential acted as the main controlling factors, and the effect of the latter was more distinct. Originality/value The initiation of pitting corrosion was revealed by the immersion test. The mechanism of pitting corrosion was analyzed and discussed.

Applicability of EIS for evaluation of corrosion resistance of aluminum flakes

2016 ◽  
Vol 63 (5) ◽  
pp. 355-359
Author(s):  
Naghmeh Amirshaqaqi ◽  
Mehdi Salami-Kalajahi ◽  
Mohammad Mahdavian
Keyword(s):  
Corrosion Resistance ◽  
Conventional Method ◽  
Design Methodology ◽  
Electrochemical Impedance ◽  
Quantitative Estimation ◽  
Surface Modifications ◽  
Organic Coatings ◽  
Nacl Solution ◽  
Content Type ◽  
Alkaline Conditions

Purpose The conventional method for evaluation of corrosion resistance of aluminum flakes is based on the volume of evolved hydrogen in acidic and basic environments. This study aims to introduce electrochemical impedance spectroscopy (EIS) as a method to evaluate corrosion resistance of aluminum flakes. Design/methodology/approach Aluminum flakes with different surface modifications were compressed to build a disk. Then, the disks were examined by EIS in NaCl solution. Also, the corrosion resistance of the flakes was evaluated by the conventional method. Findings The results revealed applicability of EIS for evaluation of corrosion resistance of aluminum flakes. Originality/value Application of EIS to evaluate corrosion resistance of aluminum flakes is novel. As it can provide fast, reliable and quantitative estimation of the corrosion resistance of the aluminum flakes in the 3.5 per cent NaCl solution. This medium is highly encountered for the aluminum flakes used in organic coatings, that is why test in NaCl solution is more convenient compared to the conventional methods using acid and alkaline conditions.

Effect of metal ions on the anti-corrosion properties of γ-glycidoxypropyltrimethoxysilane coatings on cold-rolled iron

2016 ◽  
Vol 63 (2) ◽  
pp. 82-88 ◽  
Author(s):  
Shengsong Ge ◽  
Menglong Li ◽  
Qian Shao ◽  
Ke Liu ◽  
Junxiang Wang ◽  
...  
Keyword(s):  
Metal Ions ◽  
Design Methodology ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Coating Process ◽  
Neutral Salt ◽  
Corrosion Properties ◽  
Content Type ◽  
Fourier Transformed Infrared Spectroscopy ◽  
Cold Rolled

Purpose – This paper aims to clarify the effect of metal ions added in the γ-glycidoxypropyltrimethoxysilane (γ-GPS) solutions on the anti-corrosion properties of the γ-GPS coatings on cold-rolled iron (CRI). Design/methodology/approach – The transformations of functional groups involved in reactions during the coating process were characterized by Fourier transformed infrared spectroscopy (FTIR), and the thickness of the γ-GPS coatings on the CRI substrates was measured using high-powered microscopy. The anti-corrosion properties of γ-GPS-treated samples were evaluated by neutral salt spray tests, polarization curves and electrochemical impedance spectroscopy measurements. Findings – The results show that Zn2+ and Mg2+ in the γ-GPS solutions promote the formation of Si-O-Si and Si-O-Fe bonds and improve the anti-corrosion properties of the γ-GPS coatings on CRI. However, Al3+ and Na+ in the γ-GPS solutions do not play this role. Originality/value – Although there have been previous research studies on the γ-GPS coatings on CRI, this paper is the first to study the effect of metal ions added in the silane solutions on the anti-corrosion properties of the γ-GPS coatings, and it has been confirmed that the anti-corrosion properties changed when Zn2+ (or Mg2+) is present.

Synergistic effect of chloride and NO2 on the atmospheric corrosion of bronze

2009 ◽  
Vol 56 (6) ◽  
pp. 299-305 ◽  
Author(s):  
Xia Cao ◽  
Ning Wang ◽  
Ning Liu
Keyword(s):  
Synergistic Effect ◽  
Design Methodology ◽  
Atmospheric Corrosion ◽  
Electrochemical Impedance ◽  
X Ray Diffraction ◽  
Impedance Measurements ◽  
Content Type ◽  
X Ray ◽  
Corrosion Kinetics ◽  
Tension Tests

PurposeThe purpose of this paper is to investigate the effect of chloride along with NO2 on the atmospheric corrosion of bronze using exposure tests.Design/methodology/approachSurface tension tests and electrochemical impedance measurements together with scanning electron microscopy (SEM) with energy dispersive atomic X‐ray, and X‐ray diffraction are used to characterize the corrosion behavior.FindingsThe results of the weight loss measurements show that the whole corrosion kinetics can be described approximately by: ΔW=atb; the synergistic effect of chloride and NO2 is observed clearly, though no nitrate existed in the corrosion products.Originality/valueA new catalyst theory has been suggested in this paper, i.e. that NO2 acts as a catalyst during the corrosion process when significant quantities of chloride also are present.

Surface white spot and pitting corrosion of 316 L stainless steel

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Guanghui Yi ◽  
Dajiang Zheng ◽  
Guang-Ling Song
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Pitting Corrosion ◽  
Electrochemical Impedance ◽  
White Spot ◽  
General Corrosion ◽  
Corrosion Performance ◽  
Content Type ◽  
White Spots ◽  
316 L Stainless Steel

Purpose The purpose of this paper is to address the concern of some stainless steel users. To understand the effect of surface white spots on corrosion performance of stainless steel. Design/methodology/approach White spots appeared on some component surfaces made of 316 L stainless steel in some industrial applications. To address the concern about the pitting performance in the spot areas, the pitting corrosion potential and corrosion resistance were measured in the spot and non-spot areas by means of potentiodynamic polarization and electrochemical impedance spectroscopy and the two different surface characteristics were analytically compared by using optical microscopy, laser confocal microscopy, scanning electron microscopy, x-ray diffraction, energy dispersive spectroscopy and auger energy spectroscopy. The results indicated that the pitting performance of the 316 L stainless steel was not negatively influenced by the spots and the white spots simply resulted from the slightly different surface morphology in the spot areas. Findings The white spots are actually the slightly rougher surface areas with some carbon-containing species. They do not reduce the pitting resistance. Interestingly, the white spot areas even have slightly improved general corrosion resistance. Research limitations/implications Not all surface contamination or roughening can adversely affect the corrosion resistance of stainless steel. Practical implications Stainless steel components with such surface white spots are still qualified products in terms of corrosion performance. Originality/value The surface spot of stainless steel was systematically investigated for the first time for its effect on corrosion resistance and the conclusion was new to the common knowledge.

Microstructure and corrosion resistance of Ni/Cr3C2-NiCr composite coating

2019 ◽  
Vol 66 (4) ◽  
pp. 471-478 ◽  
Author(s):  
Majid Hosseinzadeh ◽  
Abdol Hamid Jafari ◽  
Rouhollah Mousavi ◽  
Mojtaba Esmailzadeh
Keyword(s):  
Corrosion Resistance ◽  
Composite Coating ◽  
Design Methodology ◽  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Thermal Spraying ◽  
Content Type ◽  
Bath Solution ◽  
Electrochemical Deposition Method ◽  
Base Composite

Purpose In this study, electrochemical deposition method which have cheaper equipment than thermal spraying methods and is available for the production of composite coatings were used. Design/methodology/approach Composite coatings were electrodeposited from a Watts's bath solution in which the suspended Cr3C2-NiCr particles were dispersed in the bath solution during deposition. Potentiodynamic polarization and electrochemical impedance spectroscopy techniques have been used to evaluate the corrosion resistance of the composite coating in the 3.5 Wt.% NaCl solution. Findings It was found that the submicron Cr3C2-NiCr particles distributed uniformly in the coating and depend on the current density of deposition, different amount of particles can be incorporated in the coating. The results showed that the corrosion resistance of the Ni/ Cr3C2-NiCr composite coatings is more comparable to the pure nickel coating. Originality/value Production of Ni-base composite coating from an electrolytic bath containing Cr3C2-NiCr particles is possible via electrodeposition.

Effect of residual stress and microstructure on corrosion resistance of carburised 18CrNiMo7-6 steel

2020 ◽  
Vol 67 (4) ◽  
pp. 357-366
Author(s):  
Gang Wang ◽  
Yue Zhang ◽  
Chen Gao ◽  
GuangTao Xu ◽  
MingHao Zhao
Keyword(s):  
Aqueous Solution ◽  
Residual Stress ◽  
Compressive Stress ◽  
High Speed ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Electrochemical Potential ◽  
Residual Compressive Stress ◽  
Content Type ◽  
Electrochemical Tests

Purpose The purpose of this paper is to investigate, the effects of residual stress and microstructure on the corrosion behaviour of carburised 18CrNiMo7-6 steel in a 3.5% NaCl aqueous solution. Design/methodology/approach The electrochemical tests were conducted using an electrochemical workstation with a three-electrode system in a 3.5% NaCl aqueous solution, the residual stress of each working face was measured by a high-speed residual stress analyser, and microstructure of different carburised layers were observed scanning electron microscopy. Finally, the effect of carbon content, microstructure and residual stress on the corrosion behaviour of the steel was discussed. Findings The results showed that the residual compressive stress in the carburised layer initially increased and subsequently decreased with increasing depth of the carburised layer, reaching stability in the matrix layer. The electrochemical tests before and after stress reduction showed that the electrochemical impedance and the electrochemical potential increased with the reduction of residual compressive stress. Originality/value The residual compressive stress in the carburised layer initially increases and subsequently decreases with increasing carburised layer depth. The electrochemical impedance and the electrochemical potential increased with the reduction of residual compressive stress. The general relationship between electrochemical potential and residual stress was established.

Optimization of pre-oxidation time for corrosion resistance of cobalt based coating alloy in mixed sulphates

2021 ◽  
Vol 68 (1) ◽  
pp. 29-35
Author(s):  
Abdul Rehman ◽  
Mohammad Hassan Shirani Bidabadi ◽  
Liang Yang ◽  
Zheng Yu ◽  
Chen Hao ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Hot Corrosion ◽  
Design Methodology ◽  
Corrosion Behaviour ◽  
Ambient Air ◽  
Oxidation Time ◽  
Oxidation Treatment ◽  
Content Type ◽  
Surface Oxides ◽  
Oxidation Effect

Purpose This study aims to optimise the effect of pre-oxidation on hot corrosion behaviour of Tribaloy T-900 at 900 °C in mixed Na2SO4 and K2SO4. Design/methodology/approach Prior to hot corrosion experiment, pre-oxidation treatments were carried in ambient air at 900 °C for 1, 5 and 10 h, respectively. The hot corrosion experiments were performed in a box type furnace at 900 °C. Both surfaces of specimens were brushed with saturated salt solution of 75 wt.% Na2SO4 + 25 wt.% K2SO4. After brushing, the salt-coated specimens were placed in electric stove to ensure drying of salt. After drying, presence of 3 mg/cm2 salt on specimen’s surface was ensured through weighting. Findings The 1-h pre-oxidation treatment prior to hot corrosion showed superior hot corrosion resistance against molten salt attack. An optimum pre-oxidation time of 1 h helped timely formation of protective Cr2O3 layer and inhibited the formation of less stable and porous surface oxides of Ni and Mo during hot corrosion. Originality/value Pre-oxidation effect on hot corrosion behaviour of refractory metal (such as Mo in investigated alloy) containing alloy has never been reported previously. Refractory metals oxide (e.g. MoO3) could transform the corrosion phenomena to catastrophic failure through acidic fluxing.

Study of corrosion of copper in industrial cooling systems

2015 ◽  
Vol 6 (5) ◽  
pp. 617-635 ◽  
Author(s):  
Ioannis A Kartsonakis ◽  
Elias P. Koumoulos ◽  
Antonis Karantonis ◽  
Costas A. Charitidis ◽  
S Dessypris ◽  
...  
Keyword(s):  
Design Methodology ◽  
Corrosion Inhibitors ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Water Cooling ◽  
Optimum Structure ◽  
Copper Corrosion ◽  
Cooling Systems ◽  
Content Type ◽  
Industrial Systems

Purpose – The purpose of this paper is to perform the evaluation of copper susceptibility to corrosion in industrial cooling systems. Microstructure and defects of copper are observed, while divergences from optimum structure are discussed. Design/methodology/approach – Various types of corrosion are examined. Electrochemical techniques such as electrochemical impedance spectroscopy and potentiodynamic polarisation are applied in these materials, using corrosion inhibitors. Microscopic observations and electrochemical measurements are interpreted according to possible mechanistic scenarios. Findings – It is evident that, under specific conditions (e.g. high pH), water cooling ingredients can enhance corrosion, leading to significant copper mass loss from the inner surface of the pipe and thus leading to failure. Originality/value – Evaluation of copper corrosion in cooling industrial systems was done, as well as studies of copper corrosion in sodium chloride.

Effect of r-GO/TiO2 hybrid composite as corrosion-protective coating on magnesium in sulphur-based electrolyte

2018 ◽  
Vol 65 (4) ◽  
pp. 375-382 ◽  
Author(s):  
A.G. Mohan Das Gandhi ◽  
K. Soorya Prakash ◽  
V. Kavimani
Keyword(s):  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Electrochemical Behaviour ◽  
Time Interval ◽  
Nano Materials ◽  
X Ray Diffraction ◽  
Corrosive Media ◽  
Content Type ◽  
Tafel Polarization ◽  
Reduced Graphene

Purpose This paper aims to examine the investigations made on the corrosion behaviour of magnesium (Mg) substrate electrodeposited using different nano-materials. Design/methodology/approach This study uses nano-materials such as those of reduced graphene oxide (r-GO), titanium-di-oxide (TiO2) and also r-GO/TiO2 nano-composites (dispersed through ultra-sonication process) at 3-min time interval. Crystalline nature of synthesized TiO2 is studied through X-ray diffraction and its pore volume is measured to be approximately 0.1851ccg-1 by Brunauer Emmett Teller analysis. Findings Surface morphology of the developed set of specimens inspected through scanning electron microscopy and energy dispersive spectroscopy establishes a clean surface coating and further witnesses for only minimal defects. Electrochemical behaviour of the developed coating is studied exhaustively using Tafel polarization and electrochemical impedance spectroscopy in 0.1 M Na2SO4 solution. Originality/value Incremental corrosion resistance exhibited by developed composite coating owes to the factors viz. chemical stability and hydrophobic tendency of TiO2 and r-GO; these known engineering facts resist the flow of ions into the corrosive media and thereby reduce the rate of corrosion.

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