Increase In Corrosion Rate Research Articles

Blast fragility assessment of aging coastal RC columns exposed to non-uniform CIC attacks using LBE function

Along the service period of aging coastal reinforced concrete (RC) structures, chloride-induced corrosion (CIC) is a major cause affecting their life-cycle performance and durability. RC columns are the important vertical members of many long-span highway bridges and high-rise buildings, and they are vulnerable to the deterioration effects caused by non-uniform CIC and the intentional terror activities or accidental explosive attacks. The catastrophic failure of RC columns could trigger the progressive collapse of buildings and bridges, leading to huge economic losses and casualties. Very few studies have investigated the time-dependent blast fragilities of deteriorating coastal RC columns exposed to non-uniform CIC. To this end, we proposed an integrated time-dependent blast fragility assessment framework for aging coastal RC columns, considering the deterioration effects caused by non-uniform CIC in marine conditions. Firstly, a three-phase time-variant deterioration rate model for steel bars that considers the accelerated increase of the steel corrosion rate after the cover concrete cracking was incorporated in the analytical modeling of non-uniform CIC of aging RC structures. Secondly, Load-Blast-Enhanced (LBE) function in LS-DYNA was implemented to numerically simulate blast loads, and the effectiveness of the numerical models was validated by the available field blast test results reported in the literature. Subsequently, the performance damage states (e.g., low, medium, and high) of RC columns under intensive blast loads were defined in terms of the damage degree index (D) by using the LBE method, and the pressure-impulse (P–I) models were constructed accordingly. Finally, by using the scaled distance (Z) as the blast loading intensity measure (IM), Monte Carlo Simulations (MCS) were used to conduct the blast fragility analysis for a typical aging coastal RC column. The proposed time-dependent blast fragility assessment framework for aging RC columns is demonstrated to be appropriate and effective in evaluating their deteriorated blast loading-resistance, and it is also a good candidate to estimate the time-dependent blast fragilities of deteriorating coastal RC columns.

Comparative study on the corrosion behaviour of CNT-reinforced NiAl alloys in NaCl and Na2SO4 solutions

Various electrochemical techniques were used to study the corrosion behaviour of the CNT-reinforced NiAl alloys under NaCl and Na2SO4 environments. The potentiodynamic polarization curves revealed activation Tafel behaviour when the NiAl alloy specimens were immersed in NaCl solution while passivation followed by slight development of transpassivation resulted under Na2SO4 environment. The reinforcement of pure NiAl alloy with up to 1.0 wt.% CNT increased the corrosion rate from 0.10 to 0.63 mm/yr under NaCl environment, while under Na2SO4 environment, the corrosion rate increased from 0.04 to 0.12 mm/yr. The observed increase in corrosion rate with an increase in CNT reinforcement (under both NaCl and Na2SO4 environments) suggested that the reinforcement of NiAl alloys with CNT reduced the corrosion resistance of NiAl. The X-ray diffraction analysis revealed that the corrosion products consisted of oxides including Al2O3 under NaCl environment, while scanning electron microscope analysis showed a porous passive layer on the surface of the alloy specimens immersed in Na2SO4 solution.Graphical abstract

SYNTHESIS OF CALCIUM CHLORIDE FROM TECHNICAL LIME

Calcium chloride is a popular product for oil/oil, gas, chemical, chemical-pharmaceutical, forest, construction and other industries. The aim of this work is to synthesize calcium chloride from low-quality limestone, to calculate the material balance of the process of its production and to study the possibility of using CaCI2 in the oil industry. Methodology: Infrared spectra were filmed on an infrared spectrophotometer in the spectral region 225-4000 cm-1. The basic hydrochloric acid method is selected for producing calcium chloride from technical lime. The synthesis and purification of the CaCI2 solution were carried out according to a known method. Results and discussion. Experiments have shown that calcium chloride enhances the anti-corrosion properties of a seawater well-killing fluid. The highest degree of protection (89.83%) was observed at 35% CaCI2 concentration due to chemical composition. Introducing CaCI2 into wastewater increases its mineralization and overall hardness, resulting in the formation of a more aggressive environment and an increased corrosion rate. Conclusions: A feasibility study of the process of obtaining pure calcium chloride from technical raw materials was carried out, the material balance of this process was calculated, and it was shown that the cost of the resulting CaCl2 does not exceed the cost of 1 ton of pure CaCl2 on the market of services.

Influence of Cavitation in Seawater on the Etching Attack of Manganese-Aluminum-Bronzes

During cavitation investigations with manganese-aluminum-bronzes (MAB) in seawater using ultrasound (US), it was found that the microstructure of the bronze was developed by etching. To investigate this phenomenon in more detail, metallographically polished MAB samples were US-treated in synthetic seawater. On the one hand, pulsed ultrasound was used with a sonotrode in order to be able to observe the effects of cavitation. On the other hand, an ultrasonic bath with less power than the sonotrode was used to investigate the influence of ultrasound on the electrochemical response of the MAB. It was found that the k-phase is attacked most severely by cavitation, followed by β-phase and the α-phase. Potentiostatic measurements indicated that the transport of oxygen to, and of metal ions from the metal surface is enhanced by the ultrasound, which then leads to increased corrosion rates.

Under-deposit microbial corrosion of X65 pipeline steel in the simulated shale gas production environment

The synergistic effect of sand deposit and sulfate-reducing bacteria on the X65 pipeline steel was investigated in the simulated shale gas production environment, by means of weight loss tests, EIS, SEM and EDS. The results indicated that the coexistence of sand deposit and sulfate reducing bacteria (SRB) resulted in 63% reduction in uniform corrosion, but 183% increase in localized corrosion rate. The EIS results revealed that the formation of biofilm altered the protectiveness of the surface mixed layer and showed a trend related to the bacterial growth curve. The mixed layer was also clarified from the cross-section morphology and EDS analysis. This mixed layer may hinder the diffusion of substances to the deposit/steel interface, thus creating a microenvironment at the deposit/steel interface that promotes localized corrosion.

Evaluation of microbial corrosion in biofuel storage tanks using split-chamber zero resistance ammetry

Split-chamber zero resistance ammetry (SC-ZRA) was used to study microbiologically influenced corrosion by aerobic chemoorganotrophic microeukaryotes isolated from biodiesel storage tanks. The magnitude and direction of electric current were measured between two shorted carbon steel electrodes, which were deployed in separate chambers connected by a salt bridge (via a SC-ZRA assembly). This approach permitted rapid screening for the corrosive activity of these previously understudied microeukaryotes. During this study, two previously understudied microeukaryotes (Byssochlamys sp. SW2 and Yarrowia lipolytica) showed increased biomass, an increase in electrochemical signal (current), and a corresponding increase in corrosion rate (weight loss). However, other previously understudied microeukaryote (Wickerhammomyces sp. SE3) showed an increase in biomass without an increase in electrochemical signal and minimal corrosion rate, indicating that the SC-ZRA technique can screen for the corrosive activity of a microorganism, regardless of overall microbial activity. This technique could be used to quickly assess the corrosive potential for a range of previously understudied microorganisms.Graphical Abstract

On the evolution of protective oxide chemistry and corrosion resistance of electrodeposited FeCrMnNiCo-carbon nanotube composite coatings

ABSTRACT Reinforcement of carbon nanotube (CNT) into FeCrMnNiCo High Entropy Alloys (HEA) was carried out using electrodeposition method. Different volume fractions of functionalised CNTs (0.5, 1.0, 5.0, 10.0, 20.0, 30.0 mg/L) were dispersed in the aqueous electrolyte bath to synthesise HEA-CNT composite coatings. Effect of CNT addition on the phase constitution, morphology, composition, roughness, contact angle and ultimately on corrosion resistance of the pristine coating was investigated. The study revealed that the corrosion behaviour of the composite coatings was highly sensitive to the volume fraction of CNTs in the coatings. The change in the corrosion rate was, however, not monotonic and it was observed that the corrosion rate decreased progressively with CNT addition reaching a minimum followed by a sharp increase in corrosion rate thereafter. The protection efficiency of pristine coating was enhanced remarkably by 74.27% with the addition of an optimum amount (10 mg/L) of CNTs. The enhanced corrosion resistance was due to fine-grained morphology, reduced surface roughness from 1194. 9 ± 3.6 nm for pristine coating to 721.3 ± 1.8 nm for the highest corrosionresistant coating, enhanced hydrophobicity with a tremendous increase in water contact angle from 85.2° to 152.8°. Additionally, the dominance of more stable oxides of chromium (Cr2O3) and nickel (NiO) on the passive oxide layer made the coating less susceptible to corrosive media. Beyond the optimum CNT volume fraction, the drastic deterioration in corrosion-resistance observed beyond the optimum was attributed to increased surface defects in the forms of cracks due to the incorporation of agglomerated CNTs into the coating matrix.

Preliminary studies on microbial induced corrosion of ferrous materials (EN-8 and 411143 steels) in the presence of Acidithiobacillus ferrooxidans

An electrochemical investigation was conducted to evaluate the corrosion behaviour of Iron alloys such as EN-8 and 411143 in absence and in presence of microbes Acidithiobacillus ferrooxidans. Linear polarization technique was employed to measure the Polarization Resistance and corrosion rates of two different ferrous metal samples. Polarization resistance (Rp) values of EN-8 were initially higher in the presence of Acidithiobacillus ferrooxidans than the values of 411143. Growth rate of the Acidithiobacillus ferrooxidans was more and sustained longer period with EN-8 in the presence of media than in the case of alloy ‘411143’. It was observed that there was a 1.5 fold increase in corrosion rate in both the cases of EN-8 and 411143 in the presence of bacteria.High corrosion rates were recorded with the steel 41143 rather than the En-8 with respect to the optical density of the microbes. It was concluded that EN-8 was exhibited high resistance to the microbial attack.

Inhibitorska svojstava ekstrakta Rosmarinus officinalis L. na koroziju legure AA8011 u 1,0M HCl

The adsorption mechanism of Rosmarinus officinalis L. as corrosion inhibitor for Al AA8801 alloy in 1.0M HCl was studied using gravimetric method and thermodynamics studies at 303, 313, 323 and 333K. Inhibitor concentrations ranged between 0 and 1000mg/L. Results show that the adsorption mechanism of Rosmarinus officinalis L. is via physisorption, generally endothermic and accompanied by a resulting decrease in disorder. Inhibitor efficiency largely decreased with increase in temperature, and decrease in concentration of the extract. The presence of an external magnetic field enhanced the dissolution of passivating Al2O3 films, thereby increasing corrosion rate.

Experimental study on bearing capacity of corroded angle steel members of in-service transmission towers

The tower is the load-bearing structure of the overhead transmission line. Due to the complex operating environment and other factors, the transmission tower is prone to corrosion, which weakens the bearing capacity of the tower and affects the safe operation of the power grid. Through the investigation of the corrosion situation of the transmission towers in service, the angle steel members were removed from the in-service transmission towers, and the axial compression bearing capacity test was carried out. As the corrosion rate increases, the bearing capacity of components shows a decreasing trend, and due to the existence of corrosion, and at the same corrosion rate, due to the location of corrosion, The corrosion depth and corrosion area are different, and the axial compression bearing capacity of the components fluctuates greatly.

Reduced graphene oxide (RGO) reinforced Mg biocomposites for use as orthopedic applications: Mechanical properties, cytocompatibility and antibacterial activity

Magnesium (Mg) has attracted wide interest in orthopedic applications as they exhibit great biodegradability and strong biocompatibility, while corrosion is the main concern for Mg that should be addressed prior to biomedical applications. In this work, ZM31 (Mg-3Zn-1Mn)/xRGO ( x = 0, 0.5, 1 and 1.5 wt%) biocomposites were synthesized by semi-powder metallurgy method. The results showed that the RGO acting as an effective reinforcing filler to prevent deformation and showed better compressive strength (282.3 ± 9 MPa) and revealed enhancement in failure Strain (7.8 ± 2.1%) at 1 wt% RGO concentration compared to Mg alloy (244.5 ± 9 MPa and 7.1 ± 1.5% respectively). Moreover, fracture analysis indicated a more ductile fracture of the nanocomposites after the incorporation of RGO. Crack bridging, crack deflection and crack branching are dominant mechanisms for reinforcement of Mg-based containing RGO. Mg composites containing 0.5 wt% RGO showed a low corrosion rate (2.75 mm/year), while more incorporation of RGO resulted in an increased corrosion rate (4.38 mm/year). In addition, the degradation rate of ZM31 alloy (2.57 mg.cm − 2 .d −1 ) obviously decreased with the addition of 0.5 wt% RGO (1.84 mg.cm − 2 .d −1 ) in the SBF. Besides, continuous apatite layers were created on the composites in the SBF solution. Also, the cell culture examinations showed good cell viability and adhesion on composites with 0.5 and 1 wt% RGO, which was demonstrated by the SEM and MTT assay The alkaline phosphatase (ALP) activity of the ZM3–0.5RGO composite was considerably higher than that of ZM31 matrix alloy in 24 h and 48 h, implying higher osteoblastic differentiation. The antibacterial behavior toward both bacteria ( E. coli and S. aureus ) exhibited that escalating RGO concentration in Mg-matrix composites leads to further inhibition of bacteria growth. These findings suggested that ZM31–0.5RGO biocomposite could be a more promising candidate for orthopedic implants.

Acoustic Emission Assessment of Corroded RC Columns Jointly Reinforced with Concrete Canvas and CFRP

To explore the crack behaviors of corroded concrete columns jointly reinforced by concrete canvas (CC) and carbon fiber reinforced polymer (CFRP), a total of six specimen sets with different reinforcement forms and corrosion rates are designed and tested by acoustic emission (AE) technology. The assessed methods are AE characteristic parameters, RA-AF values, b values, and AE event spatial location map. The results show that the presence of CC changes the failure morphology of the specimen and improves the uneven deformation of concrete in the core area, which proves that the jointly reinforced method exhibits high plasticity deformation ability. The crack mode of the jointly reinforced specimen undergoes multiple transformations between tensile cracks and shear cracks, before ending in the final crush failure. The fluctuations in both amplitude and frequency of the b values of the jointly reinforced specimens increase significantly with time. The crack activity of concrete is more intense in this period, which proves that the jointly reinforced method ensures a more complete failure. Moreover, the increases in corrosion rate reduced the probability of shear cracks in the core concrete and further increased the failure degree of the specimen. The present study demonstrated that AE monitoring can effectively capture the characteristics of the cracking process of jointly reinforced concrete.

PENGARUH MEDIA PERENDAMAN NaCl TERHADAP LAJU KOROSI PADA BAJA ST 42 DALAM EKSTRAK INHIBITOR KULIT PISANG KEPOK

Effect of NaCl Immersion Media on Corrosion Rate on ST 42 Steel in Kepok Banana Peel Inhibitor Extraction. This study aims to determine the corrosion rate of ST 42 steel using an inhibitor of kepok banana peel extraction with various NaCl immersion media. Sample immersion time is 168, 336, 504 hours. The method used to calculate the corrosion rate is to measure the weight loss. The sample of this research was carried out in the Mechanical Engineering laboratory, Faculty of Engineering and the Pharmacy laboratory, Faculty of Mathematics and Natural Sciences, Tadulako University. The results obtained in the variation of NaCl 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, inhibitor kepok banana peel extraction 300 ppm, an increase in corrosion rate with increasing NaCl variation with the same amount of extraction inhibitor, this is because the percentage of NaCl variation greatly affects the corrosion rate.

AM60-AlN Nanocomposite and AM60 Alloy Corrosion Activity in Simulated Marine-Coastal Ambience

The initial stages of AM60-AlN nanocomposite and AM60 corrosion behaviors were compared over 30 days of exposure to solution (NaCl, Na2SO4 and NaHCO3), simulating the marine-coastal environment (SME). The incorporation of AlN nanoparticles (1.0 wt.%) in the AM60 alloy matrix favored the lower roughness of the AM60-AlN, associated with the grain refinement in the matrix. During the immersion of the alloys, pH of the SME solution shifted to alkaline values >9, and therefore, the solubility of AlN aluminum hydroxide phases were raised, followed by a slightly higher release of Mg-ions and corrosion rate increase. The chloride ions attributed to the unstability of the Al-Mn phase and Al(OH)3 corrosion product was formed in a low content. The composite AM60-AlN presented lower value of the electrochemical noise resistance (Rn), suggesting that the corrosion process occurs with less difficulty. The localized corrosion near the Al-Mn cathodes seems to be stronger on the composite surface, in area and depth of penetration. The corrosion current fluctuations suggested that the corrosion is a weakly persistent process, dominated by the fractional Gaussian noise (fGn).

Axial compressive responses of concrete canvas and CFRP reinforced corroded concrete short columns

To evaluate the axial compression performance of corroded concrete short columns reinforced by concrete canvas (CC) and carbon fiber reinforced polymer (CFRP), a total of 16 specimen sets with different reinforcement forms and corrosion rates are designed and examined in this paper. Specimens are subjected to electrochemically-induced corrosion before being mechanically tested under the compressive load. The assessed variables are theoretical corrosion rate (0, 5%, or 10%), number of CFRP wrapping layers (0, 1, 2, or 3), and number of CC layers (0 or 1). Through the signal localization of acoustic emission (AE) and the variation in characteristic parameters, it is found that the presence of CC changes the failure morphology of the specimen and improves the uneven deformation of concrete in the core area. Also, under the same number of CFRP wrapping layers, the peak stress of the CC and CFRP jointly reinforced specimens is reduced by about 10% but has a more than 70% increase in the ultimate strain compared with those of CFRP reinforced only, which proves that the jointly reinforced method exhibits high plasticity deformation ability. With an increase in corrosion rate, compared with the uncorroded specimens, the peak stress of JC specimens decreases by more than 6.9% but the ultimate strain increases by more than 15.4%. The JC specimens’ peak stress and ultimate strain models are then determined through fitting, from which a good correlation with those observed is witnessed. The comparison shows that the model has good accuracy and can provide a theoretical basis for further research for CC- and CFRP-reinforced corroded concrete short columns.

Preliminary assessment of the mooring fatigue performance of a semi-submersible platform in time-domain utilizing fracture mechanics-based approach

• Fully coupled dynamic analysis of platform-mooring system is performed in time-domain. • A self-integrated program is developed for mooring fatigue analysis through fracture mechanics-based approach. • Mooring fatigue performance of a submerged platform is studied through the remaining fatigue life at different positions of diverse lines. • The influence of corrosion on fatigue performance is investigated through a finite element model with gradual degradation. This paper aims to propose a universal time-domain fatigue evaluation method for mooring fatigue analysis of marine structures utilizing a fracture mechanics-based approach. First, the tension history of the mooring lines is calculated in the time-domain through hydrodynamic analysis and converted into mooring tension cycles with corresponding ranges via the rain-flow counting method. Subsequently, mooring fatigue performance is characterized through a self-integrated program which can realize the automatic crack propagation, Stress Intensify Factor (SIF) calculation and fatigue life prediction. Finally, a comparative study is implemented to further investigate the fatigue performance at different evaluation positions of various mooring lines under various corrosion rates. Results illustrate that fatigue life is relatively longer for mooring lines on the wave-ward side and greater at both ends of each line for the applied semi-taut mooring system. Most residual mooring fatigue life is more than 129 years with an initial surface crack of a = 0.5 mm, and the crack growth rate accelerates dramatically when reaching about 2.1% of the chain diameter. Remaining fatigue life decreases significantly under increasing corrosion rates, which is typically reduced by 39.4%, 48%, 47.8% and 38.6% for mooring lines 2, 5, 8, and 11 at 0.2 mm/year corrosion rate.

Pomegranate arils extract as a green corrosion inhibitor for mild steel: effect of concentration and temperature in hydrochloric acid

Corrosion inhibitors generated from plants and organic compounds are critical for achieving a greener environment. In this work we investigated the corrosion inhibition of pomegranate arils extract (PAE) for mild steel in 1M HCl by potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and profilometry measurements. The effects of PAE concentration (100, 200, 400 mg l–1) and temperature (298, 313, and 333 K) on the PAE inhibition efficiency were evaluated. Polarization measurements revealed that PAE was a mixed anodic-cathodic inhibitor. Corrosion inhibition efficiency was around 74% at a PAE concentration of 400 mg l–1 at 298K. However, at 333 K, the corrosion current density in the solution containing 400 mg l–1 of PAE was measured to be 1.28 mA cm−2, which was higher than that in the blank solution (0.92 mA cm−2). This increase in corrosion rate at 333 K demonstrates the negative influence of high temperatures on PAE inhibition efficiency. The PAE green inhibitor was discovered to have a physical adsorption characteristic and to obey the Langmuir adsorption isotherm.

The finite element model of chloride diffusion in pre-stressed corroded reinforcement bars of reinforced concrete structures

Introduction. The general corrosion model, made for reinforced concrete structures, must include the initiation of environmental influences such as carbonation, cracking and chloride ion penetration. It depends on the rate and degree of corrosion, corrosive effects in reduced areas, as well as the lower strength of bond between pre-stressed and unstressed reinforcement bars and concrete. The majority of earlier studies were focused on one-dimensional diffusion problems with an assumed constant corrosion rate.
 
 Materials and methods. In the aftermath of general corrosion, localized corrosion is accompanied by a release of hydrogen and alkaline water, chlorine ions. Crack propagation in reinforcement wires is calculated using the transient finite element software for chloride diffusion, which is time-dependent.
 
 Results. In most cases, the diffusion equation does not have a closed form solution, and therefore, the finite difference method can be used. The authors have shown that the corrosion rate decreases with time if current density has different water-cement ratios. If the water-cement ratio increases, the corrosion rate increases, as well.
 
 Conclusions. In a pre-stressed reinforced concrete beam, the corrosion of one bar affects the total corrosion of all bars and the reduction in the cross-sectional area of bars that does not exceed 15 %.

Corrosion behavior on carbon steel in a simulated soil solution under the interaction effect of chloride and bicarbonate ions

The effect of HCO3− and Cl− on the corrosion behavior of Q345 carbon steel in soil simulated solutions was investigated through electrochemical and surface characterizations. The results show that the sample behaves with active dissolution state in low concentration of Cl− solution while pseudo passivation of sample is observed in high concentration of Cl− solution. However, in solutions containing low concentration of HCO3−, the addition of high concentration Cl− does not result in the pseudo passivation of sample due to the formation of discontinuous film, which increases the corrosion rate. In addition, in solution containing high concentration of HCO3−, the addition of high concentration Cl− leads to much higher increase of corrosion rate. The deep corrosion pit is observed on the matrix due to the rapid rupture of FeCO3 film and the sufficient development of pitting.

The effect of bird droppings on the corrosion of steel and aluminum used in offshore applications

AbstractEngineering materials in service are frequently exposed to bird droppings (BDs). In this study, the interaction has been studied of BDs from chicken with a carbon steel, AISI 316, 22% Cr duplex stainless steel (DSS), 25% Cr super duplex stainless steel (SDSS), carbon steel with a thermally sprayed aluminum (TSA) coating, and aluminum alloy EN AW 6082. Samples with and without BDs are exposed to a cyclic salt spray test for up to 692 h (29 days). Electrochemical experiments in the presence of BDs were conducted in a syringe‐based droplet cell. Characterization of the corrosion products by infrared (IR) and Raman spectroscopy shows no build‐in of organic components into the corrosion products in the samples exposed to BDs. In general, BDs affect the anodic dissolution mechanism of metals and increase the critical pitting potential. For carbon steel, a component of the BDs acts as an anodic inhibitor, leading to passivation of the surface and decreasing corrosion rates by 1–2 orders of magnitude. For 316, BDs increase the critical pitting potential but may facilitate crevice‐like initiation of localized corrosion. There are negligible effects of BDs on the corrosion of SDSS, and no evidence either for adverse effects on DSS. TSA shows an increased corrosion rate by half to one order of magnitude with BDs, but its ability to galvanically protect a steel base material is not compromised. AW 6082 shows decreased corrosion rate, no difference in mass loss, but increased pitting in the presence of BDs. Overall, these model experiments may only be seen as the start of a more systematic understanding of the interaction of BDs with engineering materials.