Major Corrosion Research Articles

Monitoring the Corrosion Resistance of Cold-Spray Coatings with Membrane-Based Sensors

Ensuring the management of gas transportation infrastructure requires the monitoring of internal corrosion within pipelines. The utilization of membrane-based electrochemical sensors is a promising advancement in corrosion risk monitoring. These sensors demonstrate an ability to operate within humidified gas environments, previously inaccessible to conventional electrochemical monitoring methods. Simultaneously, ongoing research is delving into novel sacrificial coatings and application methods to prolong the lifespan of existing pipeline structures and minimize associated repair costs. In this context, we broaden the application of membrane-based electrochemical sensors to investigate the response of electrodes equipped with cold-spray coatings. This examination encompasses a range of fluids exhibiting varying levels of corrosivity pertinent to natural gas pipelines. Multiple sensors with 316 stainless steel working electrodes were coated with cold spray sacrificial coating then exposed to humidified gases with differing relative humidities (RH) (5 %, 50 %, and 95 %) and condensed phases with differing salt content (deionized water and 0.1 mol kg-1 NaCl solution). Three electrochemical techniques (potentiometry, impedance spectroscopy and potentiodynamic scans) were used to monitor the corrosive environment and probe the extent of coating coverage. For the conditions studied, impedance values were extremely sensitive to changes in water content through changes in the membrane resistance (from ~1 kΩ in deionized water to ~5 MΩ with 5 % RH). Polarization resistances (Rp) consistently decreased with increasing corrosivity (~3 kΩ in deionized water to 15 GΩ with 5 % RH). Scanning electron microscopy and energy dispersive X-ray spectroscopy were used to identify the extent to which corrosion products permeated the membrane after major corrosion events.

Effect of Fe2O3 on the structure and properties of Mo‐containing borosilicate glasses for nuclear waste immobilization

AbstractAs a fission product in high‐level radioactive nuclear waste, Mo has low solubility in borosilicate glass. Fe2O3 is not only a prevalent transition metal element but also a major corrosion product in high‐level radioactive nuclear waste. Against this backdrop, the effect of Fe2O3 content on the structure and chemical durability of typical molybdenum‐containing sodium borosilicate glasses for nuclear waste immobilization are studied. The results show that the samples containing more than 3.85 mol% Fe2O3, a completely homogenous amorphous glass sample is obtained. Moreover, the mechanism of the effect of Fe2O3 on the solubility of Mo is discussed in detail. In this work, a portion of Fe3+ is reduced to Fe2+ and enters into the glasses as a charge compensation ion as Fe2+O6. Concurrently, Fe3+ ions contribute to the formation of the glass networks as Fe3+O4. Iron incorporation can improve the chemical durability of the sample.

Corrosion mechanism of potassium silicate coating on Ti–6Al–4V alloys under solid NaCl deposit at 700 °C

A potassium silicate coating cured by calcium hydrogen phosphate was prepared on Ti–6Al–4V, and its protection behavior against NaCl-induced corrosion was investigated at 700 °C for 500 h by the means of thermogravimetry, SEM, EMPA, XRD and TEM. The bare Ti–6Al–4V alloy suffered severe corrosion as the thickness of corrosion production layer exceeded 2 mm after 500 h. The major corrosion production was TiO2, and sodium titanates was observed within 100 h while disappeared after long-term tests. Accordingly, a novel model for NaCl-induced corrosion of Ti alloys at high temperatures was proposed. That is, the porosity of the corrosion product is strongly correlated with the reaction between water vapor in air and sodium titanates at high temperatures. The coating exhibited excellent protection as the corroded substrate layer, which is Ti5Si3 resulted from coating-substrate reaction, is ∼6.6 μm only, and no oxide scale was formed. Dissolution of Na in the coating was identified and is believed to be associated with the protective mechanism of the potassium silicate coating, i.e. this dissolution avoids chlorination-oxidation of Ti alloy.

Cr-Free Anticorrosive Primers for Marine Propeller Applications.

Marine propellers work under severe service conditions, where they commonly suffer from mechanical, electrochemical, and biological corrosion damage. The major mechanical corrosion involves cavitation, erosion, and impingement corrosion. On the other hand, the major electrochemical corrosion involves galvanic corrosion and electrolysis. As a result, consideration of both desired mechanical and electrochemical properties is necessary when designing a marine propeller coating. In this study, a PVB (polyvinyl butyral) and an epoxy coating were formulated without corrosion inhibitors to investigate the desired coating properties for marine propeller applications. The two coatings were compared with a Cr-containing commercial marine propeller coating to investigate the advantages and disadvantages of using PVB and epoxy for marine propeller coatings. It was found that it is desirable for marine propeller coatings to be flexible to avoid cracking and flaking; to be able to withstand high pH in order to resist cathodic disbondment (electrolysis); to have adequate primer-substrate adhesion; and, ideally, to be able to self-heal when the coating is damaged (cavitation). It was found that the PVB-ZO coating has more desirable properties, and introducing self-healing properties could be one of the options for further optimization in the future.

Evolution of corrosion degradation in galvanised steel bolts exposed to a tropical marine environment

The time-dependent degradation of galvanised steel bolts subjected to marine atmospheric exposure for a maximum period of 2 years in the Wenchang marine environment of Hainan province, South China, was investigated. The results showed that the zinc coating used as a protective surface finish deteriorated quickly due to the harsh environmental conditions. The deterioration of the zinc coating resulted in premature corrosion of the underlying steel substrate as early as 6 months. The main Zn corrosion products found at the initial exposure time were simonkollite (Zn5(OH)8Cl2·H2O), hydrozincite (Zn5(OH)6(CO3)2), and zincite (ZnO). At subsequent exposure times, major steel corrosion products such as lepidocrocite (γ-FeOOH), akaganeite (β-FeOOH), goethite (α-FeOOH), magnetite (Fe3O4), and maghemite (γ-Fe2O3) were detected. Fe3O4/γ-Fe2O3 was consistently found in the rust formed at both the exposed and crevice thread regions between 6 and 24 months of exposure. Based on the geometry of the bolt fastener, the corrosion rate and phase composition distribution varied between the two regions. Differences in oxygen exposure levels, corrosion kinetics, and electrochemical stability of the corrosion products were primary factors in these distinctive corrosion behaviours.

Progress and Opportunities in Computational Modeling of Localized Corrosion

Corrosion can lead to mechanical damage near the material surface and reduce the material’s strength. It is essential to understand and simulate corrosion damage evolution for predicting the residual service life of engineering structure, reliability analysis, and corrosion-resistant design of materials. Several major novel corrosion simulation methods in the past 10 y are mainly introduced: cellular automata method, finite element method, phase field model, and peridynamics model. The computational modeling of localized corrosion is discussed and the advantages and disadvantages are compared. Finally, some difficulties in practical engineering applications such as dynamic interface tracking, multiscale and multiphysical field corrosion simulation, and standardization of corrosion simulation are proposed, and the future investigation direction is explored. With the rapid development of software science and computer technology, the operation speed and accuracy of numerical simulation will be greatly improved. The application advantages of numerical simulation in the field of corrosion will be more prominent.

Investigation on corrosion behavior of Zr-bearing TA10-based titanium alloys

This study elucidated the corrosion behavior of Ti-0.3Mo-0.8Ni-2Al-xZr (x = 0, 1, 2, 3, 4 and 5 wt.%) alloys utilizing electrochemical techniques and first-principles calculation. Results revealed that the Zr addition refined the lamellar α phase, and the corrosion resistance was monotonically enhanced by increasing the Zr content. The corrosion morphologies indicated that the β phase was more susceptible to corrosion than the α phase possessing a higher Volta potential and work function. The oxide film of the surface acted as a major corrosion influence factor instead of the microstructure of the matrix in determining the corrosion performance of Ti-0.3Mo-0.8Ni-2Al-xZr alloys.

Microstructural Understanding of Flow Accelerated Corrosion of SA106B Carbon Steel in High-Temperature Water with Different Flow Velocities.

All light or heavy water reactors fabricated with carbon steels suffer from flow-accelerated corrosion (FAC). The FAC degradation of SA106B with different flow velocities was investigated in terms of microstructure. As flow velocity increased, the major corrosion type changed from general corrosion to localized corrosion. Severe localized corrosion occurred in the pearlite zone, which can be the prior location for generating pits. After normalizing, the improvement in microstructure homogeneity reduced the oxidation kinetics and lowered cracking sensitivity, causing a decrease in FAC rates of 33.28%, 22.47%, 22.15%, and 17.53% at flow velocity of 0 m/s, 1.63 m/s, 2.99 m/s, and 4.34 m/s, respectively. Additionally, localized corrosion tendency was decreased by reducing the micro-galvanic effect and tensile stresses in oxide film. The maximum localized corrosion rate decreased by 21.7%, 13.5%, 13.8%, and 25.4% at flow velocity of 0 m/s, 1.63 m/s, 2.99 m/s, and 4.34 m/s, respectively.

Artemisia Capillaris Leaf Extract as Corrosion Inhibitor for Q235 Steel in HCl Solution and its Synergistic Inhibition Effect with L‐Cysteine

AbstractArtemisia capillaris leaf extract (ACLE) for corrosion inhibition of Q235 steel at 25–65 °C in 1 m HCl was analyzed by weight loss measurements, electrochemical tests, and quantum chemical calculations. Ultra‐high‐resolution electro‐spray time‐of‐flight mass spectrometry was used to determine the major components in ACLE. The results show that ACLE has an obvious corrosion inhibition effect. At 10 g L−1 of ACLE, the corrosion inhibition efficiency can reach 99 % at 25 °C, but the inhibition efficiency decreases with the increase of temperature. Caffeic acid (0.55 wt % in ACLE) is speculated to be a major effective corrosion inhibition component in ACLE. The adsorption of active molecules in ACLE on the Fe surface may involve both physisorption and chemisorption, and however it may incline to physisorption. The adsorption of ACLE on the Q235 steel surface is a spontaneous process and conforms to the Langmuir adsorption isotherm model. The presence of ACLE can obviously increase the apparent activation energy of the dissolution reaction of iron. The combination of ACLE and L‐cysteine has a preferable synergistic inhibition effect, with the optimal mass ratio of ACLE and L‐cysteine of 7 : 3 at 25 °C. This work may provide an alternative strategy for the corrosion inhibition of metals via the synergistic effect of plant extracts with other inhibitors.

Chemometrics applied quantitative analysis of iron oxide mixtures by terahertz spectroscopy.

A quantitative analysis method for corrosion products based on terahertz spectroscopy is proposed in this paper. Mixture samples consisting of three major corrosion products (magnetite, hematite, and goethite) were prepared in 51 different concentrations. The refractive index spectra measured by terahertz time-domain spectroscopy were projected to the 2D score diagram by performing principal component analysis. The Euclidean distances between the mixtures and pure analyte on the diagram were used to build a concentration prediction model. The results indicate that the established model can precisely predict the concentration of magnetite, which is essential for a stability evaluation of the corrosion system.

Standard testing of absorber surface durability according to ISO 22975–3 versus measured thermal and high-humidity stress of absorber surface at extreme test sites

One key component in solar thermal collectors, the solar absorber, is addressed in this paper. A well-established durability testing method for the solar absorber is the procedure described in ISO 22975–3. This standard testing procedure is used to determine the long-term behavior and service life of selective solar absorbers for use in vented flat-plate solar collectors. The thermal and humidity stress on different samples of solar absorbers during long-term outdoor exposure at different extreme sites with harsh conditions, in tropical, alpine, arid and maritime climates, were monitored. The samples were optically characterized before and after the outdoor exposure. For collectors placed in marine environments, chloride ions from sodium chloride are considered to be a major corrosion agent in these regions. To compare the effect of microclimate and ambient conditions on the corrosivity for selected outdoor exposure sites, two sets of standard corrosion coupons (aluminum, carbon steel, copper and zinc) were mounted inside and outside the solar thermal collector, respectively. After the evaluation of the measured stress factors, temperature and humidity, it was found that the corresponding testing time of the procedure for high temperature and resistance to condensed water of the absorber surface test was less than that specified by the standard, ISO 22975–3. Therefore, the standard testing procedure is testing at higher thermal and humidity loads than the investigated extreme test sites.

Green approach in anticorrosive coating for steel protection by Gliricidia sepium leaf extract and silica hybrid

The lack of non-toxic, biodegradable and easily available green corrosion inhibitor that offer analogous anticorrosive property as that of commercial toxic inhibitors is the main tailback in the area of anticorrosive coatings. Current work presents a novel green corrosion inhibitor Gliricidia sepium leaf extract and investigation of its anticorrosive activity on steel in saline environment. Promising results from preliminary analysis of crude extract prompted to the isolation of active fraction and subsequent identification of major corrosion inhibitor in it. Structural elucidation substantiated the presence of disaccharide sucrose along with two other low yield components in the active fraction. The –OH functional group present in the sucrose moiety contributes towards developing a protective layer at the metal-electrolyte interface thereby retard corrosion. The crude extract explored as a novel green alternative in epoxy protective coatings via engineering an organic–inorganic hybrid GSL-PAS. The prepared hybrid coating offered an exceptional corrosion resistance than that of reported hybrids and commercial anticorrosive pigments. Two months continuous electrochemical study validated the durability of the prepared hybrid epoxy coating, authenticated the advantage of harmonious action of active and passive inhibitor GSL and PAS, respectively, in the epoxy matrix. The present work provides a new hope to the future researchers for the application of plant extract inhibitor in protective polymer coatings without hesitation.

Oxidation of iodide by PbO2, the major lead pipe corrosion product: Kinetics, mechanism and formation of toxic iodinated disinfection by-products

Lead oxide (PbO2) formed by the oxidation of lead pipes and lead-containing plumbing materials is an important corrosion product in some drinking water distribution systems. Under certain conditions it acts as an oxidant, and we report here the effects of pH on the oxidation of I¯ by PbO2, which leads to the formation of iodine (I2) and iodate (IO3¯) as well as dissolution of Pb2+. Oxidation of I¯ by PbO2 is a multi-step pH-dependent reaction, the rate of which can be expressed as: R = 6.92 × 109 × [SA]0.67 × [I¯]2.19 × [H+]0.59 (where SA is the PbO2 surface area). I2 was the major intermediate product formed along with some HOI, and was then further oxidized to IO3¯. Based on these results, a kinetic model was developed to simulate the evolution of I¯, I2 and IO3¯ in the PbO2/I¯ reaction system. In addition, the formation of iodinated disinfection by-products (I-DBPs) in the PbO2/I¯/NOM system was evaluated under different water quality conditions, and was found to be influenced by the form of the lead corrosion products in the order: Pb3O4 > PbO2 > Pb(CO3)2(OH)2 > PbCO3. Iodoform and monoiodoacetic acid were identified as the main I-DBPs, and their formation decreased with increasing pH. It is concluded that oxidation of I¯ by lead oxides in water distribution pipes probably contributes to the formation of I-DBPs as well as Pb2+ in tap water.

Non‐invasive surface analysis of ancient bronze arrowheads with scanning electron microscopy and X‐ray powder diffractometry

In this research, surfaces of eight ancient metal arrowheads were investigated regarding chemical composition, homogeneity, and products of corrosion. To perform that, two nondestructive techniques were applied: Scanning electron microscopy coupled with energy dispersive spectroscopy (SEM‐EDS), and X‐ray powder diffractometry (XRPD). Importantly, both methods did not require sampling, cutting, nor significant cleaning of the historical artifacts, which made the measurements not only nondestructive but noninvasive too. SEM‐EDS measurements provided information on the morphology and elemental composition of the surfaces of the studied objects as well as the distribution of chemical elements on the surfaces and supported crystalline phase analysis. It was revealed that the arrowheads were cast of tin bronze, but some of them contained high amounts of lead and admixtures of antimony and arsenic while copper and tin oxides and lead carbonates were found as the major corrosion products. In some cases, distribution of elements in the surface exhibited serious nonhomogeneity, probably resulting from limited solubility of the casting metals and degradation processes. Based on the obtained results, authenticity and declared provenience of the arrowheads were assessed in reference to the characteristics of similar objects described in literature.

Sensitivity analysis of parameters affecting nano-polymer solution for water shutoff in carbonate rocks

Excessive water production impacts the economics of petroleum reservoir and often leads to their premature shut-in. Production of high saline water represents a major corrosion for casing, tubing, flow lines, and production facilities. Polymer solution has been used to control water production and to plug in high-temperature reservoirs. Most of these polymer solutions consist of polyacrylamide-based polymer and an organic or inorganic cross linker. Polyethylene mine has been used as an organic cross-linked for polyacrylamide. Literature reported that polyethylene mine can also form ringing gels with polyacrylamide copolymers in addition to polyacrylamide concentration. In this study, nano-chemical solutions has been prepared and studied in detail for their efficacy at reservoir condition. The compositions of the nano-chemicals mainly consisted of polyacrylamide mixed with nano particles, cement, coated-clay and polyethylene mine as cross-linker. The aim of using nano particles and coated-clay was to control gel performance and strength under the reservoir condition. Moreover, the effect of nano-chemical composition at higher temperature have been studied extensively on the gelation properties, elastic modulus, viscosity, and swelling ratio. Results showed that the elastic modulus and viscosity improve significantly with the increasing nano particle concentration. Coated-clay can control the gelation time as clay swallows and absorbs more formation water in the target zone, when its thin coated film breaks down, lesser water production can be predicted. Cited as: Soka, S., Sidiq, H. Sensitivity analysis of parameters affecting nano-polymer solution for water shutoff in carbonate rocks. Advances in Geo-Energy Research, 2022, 6(3): 230-240. https://doi.org/10.46690/ager.2022.03.06

Numerical simulation and constructal design applied to biaxial elastic buckling of plates of composite material used in naval structures

Thin plates when subjected to compressive loads can present a structural instability phenomenon known as buckling, causing displacements out of the plane of the plate. In addition, it is known that the use of composite materials in naval engineering can bring many benefits in the medium and long term, like the major corrosion resistance, when compared with steel structures. Moreover, for specific applications perforated plates are necessary, like passage of cables and pipes, inspection windows, among others. Therefore, to find the optimal geometry of a composite plate with a centered elliptical hole the Constructal Design (CD) was applied in association with the Exhaustive Search (ES) technique and Finite Element Method (FEM). The CD allows the evaluation of the geometry that provides the optimal distribution of imperfections, leading to the maximum value of the performance parameter used for the analysis of solids mechanics problems. Applying different laminations, it was observed an increase in the critical buckling load for a composite plate without perforations of up to 10.47%. In its turn, despite suffering a reduction in the critical load value if compared to the plate without holes, an improvement of 16.89% was observed when optimal and worst geometries for the perforated plates are compared.

Marine atmospheric corrosion of carbon steel in the tropical microclimate of Port Louis

AbstractThe atmospheric corrosion performance of S235 carbon steel is assessed when exposed to the tropical/marine aerosol pollutants of Port Louis, Mauritius. Port Louis is situated on the northwest coast and has a distinct microclimate, leading to major atmospheric corrosion concerns. In addition, sulphur dioxide emissions from three heavy oil‐fired power stations complicate corrosion prediction within the region. Mass‐loss analysis shows distinctive corrosion progression behaviours linked to the environmental and geographical variables. The formation of porous surface layers leads to a continuous increase in metal dissolution during the electrochemical process. The surface analysis reveals lepidocrocite and goethite () as the predominant rust phases, with low percentages of magnetite (), akageneite and jarosite . A key insight in the S235 atmospheric corrosion involves two stages: the early rapid corrosion stage followed by a slow stage of linear or power‐law corrosion kinetics due to the formation of stable rust phases.

Anti-corrosion properties of magnesium oxide/magnesium hydroxide coatings for application on concrete surfaces (sewerage network pipes)

The corrosion of concrete sewer pipes, mainly due to biogenic sulfuric acid (bio-corrosion), may lead to the degradation of sewerage system. The purpose of this study is to evaluate the corrosion protection that the combined magnesium oxide/magnesium hydroxide coatings can offer to concrete substrates. Four coatings with different proportions of magnesium oxide/magnesium hydroxide were prepared and applied as consumable coatings onto the surface of concrete specimens. Accelerated sulfuric acid spraying tests were used to simulate the acidic conditions, existing in most sewer pipes, and to trigger the consumption of protective coatings, due to their reaction with sulfuric acid. XRD analysis was used to evaluate the formation of gypsum, as the major corrosion product of concrete degradation. The coatings exhibited good adhesion onto the concrete substrate and their progressive consumption was confirmed by performing mass and thickness measurements. All coatings preserved the alkaline surface pH values (around 9–10) throughout the duration of acid spraying tests. The respective XRD semi-quantitative results indicated the small or zero formation of gypsum in the protected samples. Surface hardness and roughness values of the coated concrete specimens presented smaller variation, in respect to the uncoated concrete specimens. According to the results, magnesium oxide/magnesium hydroxide coatings can offer sufficient protection to concrete substrates against the sulfuric acid bio-corrosion.

Limiting nitrate triggered increased EPS film but decreased biocorrosion of copper induced by Pseudomonas aeruginosa

Biocorrosion of Cu remains a significant challenge in marine engineering but the mechanism is still not clear. The nutrients in marine environment affect the microbe’s growth and the formation of biofilm, and then affect biocorrosion of metal to a large extent. In this study, the effect of NO3− concentration in Pseudomonas aeruginosa (P. aeruginosa) medium on the formation of extracellular polymer substance (EPS) film and biocorrosion of Cu were studied. The experiments results showed that limiting NO3− in culture medium triggered increased EPS film but decreased biocorrosion of Cu induced by P. aeruginosa. With increase of NO3− content in the culture medium, the Cu surface attached less polysaccharides and proteins, but the Cu corrosion rate was accelerated. The weight loss of Cu and the maximum pit depth were both increased with increase of NO3− content. The XPS and XRD analyses indicated that the major corrosion product is Cu2O. The increased corrosion rate with increase of the NO3− level were attributed to the EET-MIC route, the formation of Cu(NH3)2+, and the more loose EPS film.

Efficacy of glutaraldehyde enhancement by D-limonene in the mitigation of biocorrosion of carbon steel by an oilfield biofilm consortium.

Microbiologically influenced corrosion (MIC) is one of the major corrosion threats in the oil and gas industry. It is caused by environmental biofilms. Glutaraldehyde is a popular green biocide for mitigating biofilms and MIC. This work investigated the efficacy of glutaraldehyde enhancement by food-grade green chemical D-limonene in the biofilm prevention and MIC mitigation using a mixed-culture oilfield biofilm consortium. After 7 days ofincubation at 37°C in enriched artificial seawater in 125mL anaerobic vials, the 100ppm (w/w) glutaraldehyde + 200ppm D-limonene combination treatment reduced the sessile cell counts on C1018 carbon steel coupons by 2.1-log, 1.7-log, and 2.3-log for sulfate reducing bacteria, acid producing bacteria, and general heterotrophic bacteria, respectively in comparison with the untreated control. The treatment achieved 68% weight loss reduction and 78% pit depth reduction. The 100ppm glutaraldehyde + 200ppm D-limonene combination treatment was found more effective in biofilm prevention and MIC mitigation than glutaraldehyde and D-limonene used individually. Electrochemical tests corroborated weight loss and pit depth data trends.