Corrosion Problems Research Articles

Modification of conducting arylidene copolymers by formation of inclusion complexes: synthesis, characterization, and applications as highly corrosion inhibitors for mild steel

Modifying the metal surface is one solution to the industry’s growing corrosion problem. Thus, via threading approach and insertion of copolymers (CoP5-7) containing polyarylidenes through the internal cavity beta-cyclodextrin β-CD, novel pseudopolyrotaxanes copolymers (PC5-7) are developed, resulting in mild steel corrosion inhibition. Inhibitors of corrosion based on β-CD molecules adsorb strongly to metal surfaces because of their many polar groups, adsorption centers, many linkages of side chains, and benzene rings. The corrosion inhibition efficiencies IE % statistics have been revised via the Tafel polarization method and Spectroscopy based on the electrochemical impedance (EIS), with PC7 achieving the highest 99.93% in 1.0 M H2SO4; they are mixed-type inhibitors. The chemical composition of the resulting PCs is determined with Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) is utilized to examine the morphological structure of the produced polymers, and X-ray diffraction is employed to identify crystallinity. Encapsulating CoP5-7 with β-CD changes the morphological structures and increases the generated PCs' crystallinity. The thermal stability of PCs is studied, indicating the presence of these CoPs within the β-CD cavities enhances their thermal stability. This research will be a stepping stone for developing high-efficiency anti-corrosion coatings and various industrial applications.

Pyrolysis mechanism of R601a/R245fa mixture: A ReaxFF-MD and DFT study

R601a/R245fa mixture is one kind of promising working fluid in ORC. In this study, the thermal decomposition mechanism of R601a/R245fa mixture was studied by reactive molecular dynamic simulation (ReaxFF-MD) and density function theory (DFT). In the R601a/R245fa mixed working fluid system, pyrolysis begins with the CC bond breaking of R601a, generating a large number of CH3 radicals, which further decompose to produce a certain amount of H radicals. Due to the presence of R245fa, the hydrogen extraction reactions between CH3, H radicals and R601a, which have low energy barriers were inhabited to a certain extent. The addition of R245fa reduces the generation of small molecule flammable gases such as H2 and CH4, however, it increases the risk of HF generation. When the molar ratio of R245fa exceeds 0.5, pyrolysis will cause more serious HF corrosion problems than pure R245fa.

Application of Organic Coating in Marine Anticorrosion

The development of navigation technology has increased maritime trade and the corrosion problem of ships has received more and more attention. Marine corrosions are mainly electrochemical, mechanical and biological corrosion. Normally, the countermeasures for marine corrosion include sacrificial anode protection, applied current cathodic protection and anti-corrosion coating. However, the first two still have great shortcomings. The sacrificial anode protection is limited by the potential difference between the metal electrodes, and the protection range is small. The applied current cathodic protection requires continuous external batteries, and the cost of detection and maintenance is high. The anticorrosive coating not only has excellent anticorrosive performance, but also has the advantages of simple operation process and low cost. Hence, anticorrosive coatings have been gradually applied to ship anticorrosion. Finally, this paper reviews the application of organic coating method in ship mooring corrosion protection, and introduces three kinds of epoxy anticorrosive coatings, polyurethane anticorrosive coatings and graphene anticorrosive coatings to meet the increasingly stringent development requirements of marine anticorrosive coatings.

Multifunctional superhydrophobic composite with mechanochemical stability for concrete protection

Chemical or electrochemical corrosion of the concrete-based facilities causes potential safety hazards. Endowing the concrete with a commercial superhydrophobic coating with designed surface topography and chemical composition is an effective way to prevent the corrosion of the internal rebars. Although several methods have been adopted to combat the corrosion problem, developing an equipment-free, low-cost and scalable strategy for fabricating a robust superhydrophobic coating on the concrete surface is still a challenge. In this work, a robust superhydrophobic epoxy fixed corundum-silica-polydimethylsiloxane (ECSP) composite is fabricated as the concrete modification coating through an “armour” protection methodology via a facile and low-cost dip-coating process. The as-prepared ECSP composite consists of corundum microparticles (MPs) confined in the epoxy (EP) adhesive layer and silica nanoparticles (SiO2 NPs) modified with a low-surface-energy coating. The corundum MPs with high rigidness and hardness function as a robust, protective “armour” structure, while the polydimethylsiloxane-modified SiO2 NPs reside within the “armour” structure to provide superhydrophobicity. Benefitting from the armoured structure, the ECSP composite coated concrete exhibits an excellent robustness under various harsh conditions including mechanical abrasion, knife scratching, tape-peeling treatment, water jetting, UV irradiation, temperature treatment and chemical corrosion. Importantly, the ECSP composite coating successfully prevents the concrete (with a rebar in it) from the chemical and electrochemical corrosion. The corrosion current density (4.8 × 10−6 A·cm−2) of the ECSP coated concrete is two orders of magnitude lower than that of the unprotected concrete (1.17 × 10−4 A·cm−2), exhibiting its excellent corrosion resistance. Besides, the superhydrophobic ECSP composite coating can retard the formation of ice on the concrete surface at the temperature of −20 °C, exhibiting good anti-icing performance. This work opens a new avenue for the fabrication and application of the multifunctional superhydrophobic coating for concrete protection.

The Effects of Corrosion Problems on the Performance of Oil Wells Operated with Electrical Submersible Pumps: Lessons Learned

The Effects of Corrosion Problems on the Performance of Oil Wells Operated with Electrical Submersible Pumps: Lessons Learned

Experimental and computational optimization of eco-friendly mortar blocks for high temperature thermal energy storage of concentrated solar power plants

New avenues for thermal energy storage (TES) need to be investigated due to the lack of competitiveness of concentrated solar power (CSP) technologies. Solutions must be found to replace molten salt tanks which have a major economic impact and are difficult to maintain due to corrosion problems. In this sense, concrete represented an attractive candidate by proving excellent sensible TES in CSP. However, its main phase, made of Portland cement (PC), has significant environmental consequences. The production of PC is known to emit high levels of polluting gases, particularly the CO2. It is estimated to be responsible for between 5% and 7% of the world's CO2 emissions, making it a major contributor to climate change. This work presents greener cementitious materials, made of alkaline cements and hybrids cements, to be used as alternative eco-friendly TES media in CSP plants. An experimental campaign is presented which shows that these eco-efficient materials can have better mechanical properties, than the ordinary PC mortar, when exposed to high temperatures, in addition, can offer improvements of their thermal properties (thermal conductivity or specific heat). Second part of the work is devoted to Finite Element simulations, with the aim to find the best configuration, in terms of selection of materials and geometry, which are more efficient as TES system. The work is showing the following advancements in CSP technology by using alternative eco-friendly binders: the installation volume can be reduced by 17%, compared to a molten salt tank, while the heat exchanger's surface area can be resized by 29%, compared to the reference system using PC. These improvements enable wider variations in CSP operational efficiency and dynamic capabilities and represent important progress towards developing more efficient and sustainable CSP technologies.

SEQUENCE OF SELECTED QUALITY MANAGEMENT TOOLS TO ANALYZE QUALITIVE PROBLEMS OF PRODUCTS

Identification of causes of incompatibilities of the products treated with the powder method allows their elimination or minimization of those differences, which contributes to the improvement of the powder coating method and thus to the development of processes in the field of metallurgy. The aim of the article is to analyze the corrosion problem on the ventilator cover with the use of the sequence of selected quality management instruments (Ishikawa diagram and the 5Why method) and proposed actions to eliminate or minimize the problem and improve the powder coating process and organization within the workplace place of the selected company. The analysis was carried out at the request of the management of the Podkarpackie fan producer. The management wanted to analyze some of a problems in the simple and cheaper way, and thus in the enterprise this using the types of the method was not practiced. The management were wanted to analyze the problem with using these types of method because, in this enterprise, this was not practiced yet. The analysis of corrosion using the new sequence – Ishikawa diagram and 5Why method allowed, i.e.: appropriate analysis of the problem, identified the root cause of adequate problem and proposed the actions for the problem, thanks to which is possible to improve the powder coating process and a good organization workplace in the selected company. The sequence used and the proposed improvement actions can be used to analyze quality problems in other production and service companies.

Hybrid Semiconductor Photocatalyst Nanomaterials for Energy and Environmental Applications: Fundamentals, Designing, and Prospects

AbstractThe degradation of fossil fuel and worse environmental conditions leads to the emergence of hybrid semiconductor (SC) nanomaterials as photocatalysts. Hybrid SCs have interesting physical, mechanical, optical, chemical, and electronic characteristics. Due to these properties’ absorption of light and transfer of charge takes place frequently and hence act as multifunctional surface. These materials should be attributed to their optical and electrical properties and act as multifunctional surfaces in energy production, fuel generation, environmental remediation, sensing, etc. When SCs combine with noble, non‐noble metal, metal oxide, and some carbon‐based materials, they explore wide applications in various fields. Photocatalysis is an effective and sustainable technology to reduce or fix energy concerns and environmental corrosion problems. By going through the extensive literature review, few topics are focused on designing and working mechanisms of hybrid materials. In this way, the present review article explains the properties, surface‐interface engineering, design, and applications (energy and environmental) of hybrid nanomaterials, emphasizing their photocatalytic nature. Additionally, the appealing directions, scientific challenges, and the reasons behind the poor stability of Hybrid SC photocatalyst nanomaterials for energy and environmental applications are discussed. Finally, the concluding remarks and the current challenges with future prospects in this domain are highlighted.

Eccentric compression behavior of seawater and sea sand concrete columns reinforced with GFRP and stainless steel bars

Using FRP bars instead of steel bars to reinforce concrete columns in harsh environments has become an important method for solving corrosion problems. FRP bars have high tensile strength but low compressive strength and high brittleness, while stainless steel (SS) bars have high tensile and compressive strength and good ductility. Therefore, this paper studied the eccentric compression behavior of seawater and sea sand concrete (SSC) columns reinforced with GFRP and SS bars, in which GFRP bars were arranged on the tension side and SS bars were arranged on the compression side to improve the ductility and to analyze the effect of axial stiffness of reinforcement on the N-M interaction diagrams. A total of 48 SSC columns were designed, of which 20 were reinforced with GFRP and SS bars, 14 were reinforced with GFRP bars and 14 were reinforced with SS bars. To analyze the eccentric compression performance of SSC columns and propose the bearing capacity calculation equation, test variables were designed, including the reinforcement type, reinforcement ratio, and eccentricity, to ensure that the equation had certain universal applicability. The three failure modes of compression failure, combined compression-bending failure, and bending failure were found with the increase in the eccentricity for the GFRP and SS bars reinforced SSC (GFRP-SS-SSC) columns. The ductility indices of the GFRP-SS-SSC columns were approximately 1.5 times those of the GFRP bars reinforced SSC columns, which indicated that the ductility could be improved by replacing the compression GFRP bars with SS bars. Finally, the theoretical N-M interaction diagrams were established through the cross-section force analysis and compared with the experimental N-M interaction diagrams. Moreover, the failure mode is influenced by varying the axial stiffness of the longitudinal bars on both sides of the column section by analyzing the N-M interaction diagrams.

Modelling of 3D periodic cathodic protection problems in reinforced concrete structures with accelerated boundary element method

The steel used for concrete reinforcement exhibits either active or passive electrochemical behavior. As long as the concrete environment remains highly alkaline, the steel remains passive. However, carbonation and/or chloride contamination of concrete will cause steel to become active and corrode. In the latter case, a common strategy is the use of cathodic protection (CP) systems to lower the potential of the steel at a protective level. The numerical modelling of cathodically protected concrete buildings and infrastructures usually requires large-scale models due to their size and complex geometry. An efficient modelling approach is to consider any possible periodicity in these problems by applying periodic boundary conditions to a representative volume element of the structure. The boundary element method (BEM) is extensively used for solving CP problems. A BEM formulation is proposed for solving 3D periodic CP problems in this work. The computation cost is reduced by applying acceleration techniques based on adaptive cross approximation (ACA). As an engineering application, a sacrificial anode CP system of a reinforced concrete column is designed, illustrating the importance of detailed modelling in the design of such systems. To this end, the macrocell corrosion problem is initially solved, and a parametric study with respect to concrete conductivity is carried out.

Enhancement of corrosion protection of metal carbon steel C45 and stainless steel 316 by using inhibitor (Schiff base) in sea water

This research has presented a solution to the problem faced by alloys: the corrosion problem, by reducing corrosion and enhancing protection by using an inhibitor (Schiff base). The inhibitor (Schiff base) was synthesized by reacting of the substrates materials (4-dimethylaminobenzaldehyde and 4-aminoantipyrine). It was diagnosed by infrared technology IR, where the IR spectrum and through the visible beams proved that the Schiff base was well formed and with high purity. The corrosion behavior of carbon steel and stainless steel in a saline medium (artificial seawater 3.5%NaCl) before and after using the inhibitor at four temperatures: 20, 30, 40, and 50 C° was studied by using three electrodes potentiostat. The corrosion behavior was studied by cathode and anode polarization through which all corrosion parameters were investigated which include: corrosion current icorr (1341× 10-7- 5393 × 10-9A/cm2), corrosion potential Ecorr (-1.031- -0.227 mV vs SCE) , corrosion rates CR (0.658-0.007 mm.y-1), inhibition efficiency %IE (92-98%), and energy activation barriers Ea (4.709-26.733 kJ/mole). The thermodynamic and kinetic properties of the corrosion behavior of these two metals under study, which include: enthalpy ∆H*(2.153-24.176 kJ/mole), entropy ∆S*(-197 -156 J/mole), and free Gibbs energy ∆G*(59.87-74.56 kJ/mole) before and after using the inhibitor, were also studied.

A Critical Review on Corrosion and Fouling of Water in Water Distribution Networks and Their Control

Corrosion and scaling are among the problems that may arise when storing water in tanks. Several factors affect the corrosion and scaling of water, which include pH, temperature, alkalinity, Ca2+ hardness, TDS, concentrations of Cl–, SO42–, CO32–, and HCO3–. Also, several indices can be measured using these properties such as the Langelier saturation index, Ryznar index, Aggressive index, Larson, Scold index, water quality index, and Puckorius index. These indicators determine the degree of corrosiveness and sedimentation of water. The purpose of this review article was to study the impact of various factors on the corrosiveness and sedimentation of water. To this end, different sources of water in different countries were studied and the impact of physical and chemical parameters on their corrosiveness was investigated. Also, the reaction mechanism of water corrosion inside the pipe was studied. Finally, practical and constructive suggestions were presented to solve the problems of corrosion and sedimentation of desalination water.

Quantitative Evaluation of Corrosion Defects on Structural Steel Plates via Metal Magnetic Memory Method

ABSTRACT The detection and evaluation of corrosion defects take on a critical significance to ensure the service safety of steel structures in civil engineering. The quantitative evaluation of corrosion defects has not been well addressed though metal magnetic memory (MMM) testing technology has been investigated in steel corrosion problems. In this study, the Q345qD steel plates were taken as the specimens of MMM testing. Specimens with different corrosion degrees were developed through electrochemical corrosion, and the change laws of the MMM signals and the characteristics of different corrosion specimens were analyzed. A three-dimensional (3D) magnetic charge model of the corrosion area was built based on the magnetic charge theory, such that the change laws of the MMM signal in the corrosion area from the mechanism were explained. The finite element simulation results of the corrosion specimens were well consistent with the experimental and theoretical results. A quantitative evaluation method for corrosion defect depth was proposed in combination with finite element simulation and experimental data. Comparing the experimental data and the inversion data, the relative errors of the determined defect depth h were within 20%, suggesting that the proposed evaluation method is feasible for the quantitative evaluation of steel corrosion depth.

Flexural behavior and serviceability performance of SSC beams reinforced with hybrid GFRP-stainless steel bars

Using fiber-reinforced polymer (FRP) bars instead of steel bars to reinforce concrete structures has become an important method to solve the corrosion problems. FRP bars reinforced concrete (FRP-RC) beams suffer sudden failure owing to the brittleness of FRP bars. Therefore, it is suggested to add steel reinforcements in FRP-RC beams to improve the ductility. This study analyzes the flexural performance of seawater and sea sand concrete (SSC) beams reinforced with hybrid GFRP and stainless steel (SS) bars, in which GFRP bars are used as tension bars while SS bars are used as compression bars. The flexural performances of GFRP bars reinforced SSC beams and SS bars reinforced SSC beams were also studied for comparison. Based on the test results, the cracking moment, load-carrying capacity, deflection, and ductility of the SSC beams are discussed and compared with the guidance in current design codes. Results show that ACI 440.1R-15 and CSA S806-12 reasonably predict the cracking moment and bearing capacity, but both underestimate the deflection at the service load. Furthermore, the moment capacity calculation equation is proposed with good accuracy. The ratio between the reinforcement ratios of GFRP bars and SS bars is suggested to meet the ductility requirement.

Corrosion Resistance of CeO2-GO/Epoxy Nanocomposite Coating in Simulated Seawater and Concrete Pore Solutions.

Reinforced concrete structures in the marine environment face serious corrosion risks. Coating protection and adding corrosion inhibitors are the most economical and effective methods. In this study, a nano-composite anti-corrosion filler with a mass ratio of CeO2:GO = 4:1 was prepared by hydrothermally growing cerium oxide on the surface of graphene oxide. The filler was mixed with pure epoxy resin at a mass fraction of 0.5% to prepare a nano-composite epoxy coating. The basic properties of the prepared coating were evaluated from the aspects of surface hardness, adhesion grade, and anti-corrosion performance on Q235 low carbon steel subjected to simulated seawater and simulated concrete pore solutions. Results showed that after 90 days of service, the corrosion current density of the nanocomposite coating mixed with corrosion inhibitor was the lowest (Icorr = 1.001 × 10-9 A/cm2), and the protection efficiency was up to 99.92%. This study provides a theoretical foundation for solving the corrosion problem of Q235 low carbon steel in the marine environment.

Catalytic hydrolysis of epoxyfatty esters with solid sulfonic acids

Four sulfonic resins are able to promote the hydrolysis of several epoxyfatty esters becoming a very interesting strategy to obtain polyols from epoxyfatty derivatives. The choice of the aqueous solvent and temperature is critical to improve the accessibility of reagents to the acidic catalytic sites. Tert-butanol/water mixture as solvent at 80 °C allows to obtain good results with all resins. The recovery of the heterogeneous catalyst during at least 11 reaction cycles avoids the drawbacks of the homogeneous ones including corrosion problems. In addition, this procedure can be applied to several epoxyfatty esters with different chain size, stereochemistry of the epoxide or with additional functionalities, obtaining good yields of structurally different polyols.

Interfacial bond between modified micro carbon fiber and high-strength cement paste in UHPC: Bond-slip tests and molecular dynamic simulation

The use of carbon fiber (CF) as the reinforcement in ultra high performance concrete (UHPC) can avoid the steel fiber corrosion problem in harsh environment. The interfacial bonding between CF and matrix play a key role on the composite performances. However, the interfacial bonding between CFs with different surface treatments and the high strength paste in UHPC are not yet clear. According to micro CF pull-out tests in this study, the chemical debonding energy of anodized CF and epoxy sizing CF increased by 117.0% and 41.8%, respectively, compared with that for non-modified CF. Correspondingly, the CF/matrix bond strength enhanced by 88.6% and 29.1%, respectively. More attachments were found on the surface of the anodized CF pulled out from the matrix, and its interfacial friction bond strengths was improved by 67.8% after anodizing. Molecular dynamic simulation shows that the oxygen-containing groups (-OH, =O and –COOH) on the surface of CF can form a strong van der Waals force with C–S–H gel, and hydroxyl and carboxyl groups can also form hydrogen bonds with oxygen atoms in C–S–H gel, which is even stronger than van der Waals force. Moreover, the hydrogen bonding ability of carboxyl groups is 1.5 times higher than that of hydroxyl groups. Therefore, it can be more effective to improve the bonding between CFs and paste matrix by grafting carboxyl groups to the CF.

Finite Element Method Analysis in Simulation of Induction Heater Using Helical Coil Method

The problem of corrosion is very common in aircraft structure. This phenomenon is happened because of the two different types of material are in contact under moist or water. Along the operational hours of the aircraft structure, this corrosion is identified during the maintenance activity. To study about the corrosion removal by using the helical coil method, in this research the simulation of the removal corrosion in bolt and nut joint are conducted. The aim of the analysis i.e., to get the optimum electric current and frequency for induction heaters to heat stainless steel nuts that cannot be open, or the threads are stuck. The study was carried out so that the stainless-steel nuts reached a temperature of 400°C in one minute. Several variations of the electric current are carried out with magnitudes, namely 30 A, 40 A, 50 A and frequency variations of 300 kHz, 400 kHz, 500 kHz. Based on the variation of the electric current and frequency, the optimal electric current and frequency is generated to heat a stainless-steel nut that cannot be opened, or the screw is stuck at 50 A and 500 kHz with a temperature of 394°C in one minute.

Perspectives of Flow Assurance Problems in Oil and Gas Production: A Mini-review

Flow assurance is essential to a sustainable oil and gas production system; if not managed appropriately, it may cause huge CapEx/OpEx and is also a life-threatening phenomenon. Therefore, a systematic investigation of the formation/deposition mechanisms and reliable mitigation/management strategies is vital to control the significant flow assurance problems of gas hydrates deposition/blockage, wax/asphaltenes deposition, multiphase flow, scale formation, sand transport, and corrosion problems. This review aims to deliver rationalized and brief information accumulated in the current state of the art on all kinds of flow assurance issues faced by the oil and gas industries. This review will offer new insights into the fundamental mechanistic steps of deposition and blockage in oil and gas production systems that assist in developing new inhibition chemistries. The innovative techniques utilized to probe the depositions and assess the inhibitor’s performance are also presented along with their advantages and limitations. Overall, this paper will support flow assurance engineers in managing pipeline blockage risk triggered due to the problems mentioned above.

Trace Lattice S Inserted RuO2 Flexible Nanosheets for Efficient and Long-Term Acidic Oxygen Evolution Catalysis.

Pursuing highly active and long-term stable ruthenium (Ru) based oxygen evolution reaction (OER) catalyst for water electrolysis under acidic conditions is of great significance yet a tremendous challenge to date. To solve the problem of serious Ru corrosion in an acid medium, the trace lattice sulfur (S) inserted RuO2 catalyst is prepared. The optimized catalyst (Ru/S NSs-400) has shown a record stability of 600 h for the solely containing Ru (iridium-free) nanomaterials. In the practical proton exchange membrane device, the Ru/S NSs-400 can even sustain more than 300 h without obvious decay at the high current density of 250mA cm-2 . The detailed investigations reveal that S doping not only changes the electronic structure of Ru via forming RuS coordination for high adsorption of reaction intermediates but also stabilizes Ru from over-oxidation. This strategy is also effective for improving the stability of commercial Ru/C and homemade Ru-based nanoparticles. This work offers a highly effective strategy to design high-performance OER catalysts for water splitting and beyond.