Cathodic Corrosion Protection Research Articles

One pot synthesis of amino silane grafted cerium phosphate (AS@CePO4) as an effective anticorrosion nanopigment for epoxy coating

This work proposed a facile method to synthesize an effective anticorrosion nanopigment based on amino silane grafted cerium phosphate for epoxy coated steel system. CePO4 nanoparticles were synthesized from Ce(NO3)3 and Na3PO4 precursors, then surface-grafted with a coupling agent N-2-(aminoethyl)-3-aminopropyl trimethoxysilane (denoted as AS) via a one-pot reaction to obtain the AS@CePO4 nanopigment. The effectiveness of this nanopigment on corrosion protection, dry/wet adhesion strength, and cathodic disbondment resistance was thoroughly evaluated on an epoxy-coated steel system. The composition and morphology of pigments as well as epoxy containing pigments were characterized by Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) methods. The adhesion strength, cathodic disbondment resistance and corrosion protection performance characteristics of the coatings were evaluated by pull-off test, cathodic disbondment test, electrochemical and salt spray tests, respectively. The synergic effect from stronger bonding of AS coupling agent and excellent inhibitory ability of CePO4 led to strengthened adhesion strength, better corrosion protection performance, and higher cathodic disbondment resistance of epoxy coated steel system.

Efficient self-powered cathodic corrosion protection system based on multi-layer grid synergistic triboelectric nanogenerator and power management circuits

The last few years have seen a boom in the use of triboelectric nanogenerators (TENGs) for capturing wave energy in the ocean. This work reports a multi-layer grid synergistic triboelectric nanogenerator (MLGS-TENG). In this work, the independent layer triboelectric nanogenerator in the grid format is skillfully employed, and the design of the multi-layer parallel structure can effectively increase the capture rate of blue energy in the ocean. The shell of the triboelectric nanogenerator adopts a gyroscopic structure, which, when combined with its internal architecture, operates effectively on the surface of ocean waves. Moreover, it can be very effective in harvesting low-frequency wave energy in the ocean and converting it into mechanical energy, and then converting it into electrical energy through the friction of the internal self-assembly layer. In low-frequency mechanical tests, when the frequency is about 1 Hz and the load impedance is 400 MΩ, the peak power output of the generator in a single layer can reach 77 mW/m2. Given the excellent energy harvesting performance of MLGS-TENG, it is applied to build a high-efficiency cathodic corrosion protection system in conjunction with a buck rectifier circuit. This work is of great significance for the wide application of triboelectric nanogenerators in the marine environment and provides a feasible way to ensure the long-term stability of offshore platforms.

Cathodic Corrosion Protection on Low Carbon Steel Type H-beam (SM490YB) Using Zinc (Zn) Anode with Soil Corrosive Media Mixed with NaCl

Cathodic Corrosion Protection on Low Carbon Steel Type H-beam (SM490YB) Using Zinc (Zn) Anode with Soil Corrosive Media Mixed with NaCl

Corrosion monitoring of reinforced concrete structures: The DGZfP specification B12 Collaboration

AbstractCorrosion monitoring of reinforced or prestressed concrete structures has become increasingly important in recent years. Areas of application include components that are no longer accessible after completion or where potential field measurements cannot be carried out due to existing coatings. Corrosion monitoring can also be used to monitor the progress of corrosion in corroding systems, e.g. to prove the success of repair measures according to repair principle 8 in accordance with EN 1504‐9 or repair method 8.3 in accordance with the DIBt repair guideline. It also could be used to prove the functionality of cathodic corrosion protection systems in accordance with ISO 12696. Despite the increasing importance of corrosion monitoring, no guidelines or recommendations existed until 2018. This gap was closed by the English version of specification B12, “Corrosion Monitoring of Reinforced and Prestressed Concrete Structures,” of the German Society for Non‐Destructive Testing, which was published in 2021. This article introduces specification B12 by explaining the basic measurement principles and illustrating the potential of corrosion monitoring in new and existing buildings.

Binary Aluminum Alloys from 1-ethyl-3-methylimidazolium-based Ionic Liquids for Cathodic Corrosion Protection

Aluminum cannot provide continuous cathodic corrosion protection under ambient conditions due to the formation of an insulating oxide layer and therefore it should be alloyed. Binary aluminum alloys with Cr, Zn and Sn from AlCl3/1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) containing CrCl2, ZnCl2 or SnCl2 have been deposited and their morphology and composition were investigated using SEM/EDS. The corrosion behavior of alloys with 2–4 wt% Cr, Zn or Sn was investigated using potentiodynamic polarization in 3.5 wt% NaCl solution, neutral salt spray test (NSS) and environmental exposure (EE). Pure aluminum provides excellent corrosion protection of steel in a chloride-containing environment, but not under ambient conditions. AlCr alloys show poor corrosion protection while AlZn alloys provide excellent corrosion protection in the NSS test and superior cathodic protection in the EE test compared to aluminum. AlSn alloys are highly active at even low tin contents and dissolve rapidly in chloride-containing electrolytes. However, a slightly improved cathodic protection in the EE test compared to pure aluminum has been observed. The results prove the necessity of alloying aluminum to achieve effective cathodic corrosion protection under mild atmospheric conditions.

3D Analysis of Pipeline with Cathodic Corrosion Protection

Abstract Natural gas is an indispensable resource for human life. Its transport is usually done through underground pipelines. Due to the environment in which they are placed, the pipelines are subjected to a continuous process of corrosion. This paper aimed a 3D numerical analysis using specialized software (COMSOL Multiphysics) to study several parameters that influence the corrosion of underground pipelines. Starting from real geometric and environmental data, a comparative analysis was performed, considering the pipeline coating (e.g., with HDPE - high- density polyethylene), the placement of the cathode protection electrode, and the soil conductivity near the pipeline. The results confirm the need to cover the pipelines and can be a starting point for choosing the final configuration of the cathodic protection system.

The Electrochemical Behavior of As-Prepared Aluminum Alloy A360 Produced by Selective Laser Melting Fabrication with and without a Trivalent Chromium Process Conversion Coating

We report herein on the electrochemical behavior and corrosion resistance of as-prepared aluminum alloy, A360 (AlSi10Mg), fabricated by additive manufacturing, with and without a trivalent chromium process conversion coating. Selective laser melting was the 3D printing process used for the alloy build. The corrosion suppression provided by the coating system was assessed through electrochemical measurements and accelerated degradation testing during a 14-day continuous neutral salt-spray exposure. The results indicate that the conversion coating can be formed by solution pretreating (degreasing and deoxidation) the alloy (X-Z plane perpendicular to the build plane) with its native surface roughness (as-prepared) followed by immersion for 10, 15 or 20 min in the coating bath. All three immersion times provide an equivalent level of corrosion protection to the alloy. The conversion coating suppresses both anodic and cathodic currents, increases the polarization resistance, and provides both anodic and cathodic corrosion protection to the as-prepared alloy. The conversion-coated specimens exhibit good stand-alone corrosion resistance during a 14-day neutral salt-spray exposure with corrosion intensity values (g/m2-year) ∼10x lower than values for the uncoated, as-prepared alloy specimens.

Up-Scaling and Stabilization of Processes for the Electrodeposition of Aluminum Alloys for Corrosion Protection

Aluminum and its alloys have excellent properties (e.g. specific weight, corrosion resistance) that are beneficial for a wide range of industrial applications. By forming a natural oxide layer of a few nm thickness, these materials are able to protect themselves from the progression of corrosive attack. Unfortunately, this oxide layer limits the use of pure aluminum for cathodic corrosion protection. Adding the right alloying elements can help to prevent the formation of the oxide layer and thus self-passivation.Electrodeposition is an elegant and cost-efficient method to deposit thin films on substrates with complex shapes. The choice of the electrolyte, its composition and the deposition parameters allow the tuning of the layer properties. Electroplated aluminum materials open up the possibility of replacing environmentally hazardous materials such as cadmium. Aluminum cannot be electrodeposited from aqueous electrolytes due to its negative Nernst potential (-1.66 V vs. NHE). Non-aqueous media make this possible due to large electrochemical windows. However, they are often limited by expensive and highly flammable chemicals (e.g. SIGAL and REAL process). High investment costs for process and plant technology are the consequence. Ionic liquids (ILs) allow the deposition of reactive metals such as aluminum at room temperature. They have a very low vapor pressure and are non-flammable. In addition, they exhibit good solubility for numerous metal salts and lower differences in the deposition potentials of the metals.This paper discusses the use of imidazolium-based chloroaluminate ILs for the electrochemical deposition of aluminum alloys for cathodic corrosion protection of high-strength steel. As an essential part of upscaling IL-based processes, the use of multianodes, their limitations, and the use of additives to optimize the deposition process and the coating properties will be discussed.

IoT-Based Solar Energy Measurement and Monitoring Model

In the early days, greenhouse energy did not pay much attention to coating inspections and new applications, spending more attention on repair solar energy projects instead. However, these attitudes have recently changed. Energy producers realize that preventing corrosion and deterioration is less expensive than solving the greenhouse problems when they occur. The proposed model also provides coating, paint control, and error analysis services within the scope of solar machinery and equipment-related services while the greenhouse equipment reached a low energy level. The greenhouse monitoring services ensure that a solar plant is economical, reliable, and of high quality, meets legal requirements, conforms to standards published by domestic and foreign organizations, and determines conditions that cause short circuits or power outages. In this context, with the help of cloud computing-based Internet of things (IOT), the industrial power stations, high-voltage substations, low-voltage networks, power stations that comply with legal regulations on safety from electricity, electrical installations for machinery, alarm systems, fire alarm systems, cathodic corrosion protection mechanisms in oil tanks and pipelines, emergency power supply installations, electrical installations in buildings, and gas alarm systems are inspected and documented.

On the origin of micro-cracking in zinc-coated press hardened steels

Zn-coated press hardened steels (PHS) are in high demand for automotive mass reduction and enhanced passenger safety applications while the Zn coating supplies robust cathodic corrosion protection. However, the mechanism of micro-crack formation during direct hot-press forming (DHPF) has not been adequately described. Thus, the objective of this work was to determine the mechanism for micro-crack formation in Zn-coated DHPF PHS that addressed the relationship between micro-cracking and the coating microstructure created during substrate austenitization. Zn-coated 22MnB5 steel sheets were annealed at 900 °C for annealing times ranging from 30 to 780 s and DHPF at 75 °C s−1 to obtain a fully martensitic substrate microstructure. The inward diffusion between the Zn coating and the substrate during annealing resulted in a dual phase coating microstructure initially comprising Γ-Fe3Zn10 + α-Fe(Zn), transitioning to a single phase α-Fe(Zn) coating after annealing for 240–420 s. Coincident coating α-Fe(Zn) and substrate Zn-enriched austenite (γ-Fe(Zn)) grain boundaries became Zn-enriched, forming a thin layer of α-Fe(Zn) along the γ-Fe(Zn) grain boundaries. It is proposed that coincident coating α-Fe(Zn) and substrate prior austenite grain boundaries (PAGBs) were weakened by this grain boundary α-Fe(Zn) layer. Upon the application of tensile stress, intergranular fracture occurred along the coincident coating α-Fe(Zn) and Zn-enriched PAGBs in the Zn-enriched martensite (M(Zn)) layer. It was further determined that crack propagation ceased and the crack tip was blunted when Zn-enrichment along the PAGBs in the M(Zn) layer was exhausted.

Effect of intermetallic compounds on the mechanical property and corrosion behaviour of aluminium alloy/steel hybrid fusion-brazed welded structure

Al alloy/steel joint was produced by fusion-brazing welding with different heat inputs to obtain intermetallic compounds (IMCs) layer with different thicknesses. Following by enhancing heat input, not only the FeAl binary IMCs (Fe2Al5 and Fe4Al13) became thicker at the interface, the formation of Fe-Al-Si ternary IMCs, such as Fe2Al8Si, also became evident. Nevertheless, the joint strength was maintained at a high level. An increase of corrosion current density with three orders of magnitude was identified when the joint was welded under a high heat input (>632 J/cm) due to the appearance of enhanced tunnelling corrosion caused by ternary IMCs with weld seam. Binary IMCs became less corroded with the increase of heat input arising from the cathodic corrosion protection. Therefore, a low heat input should be utilised to preserve the corrosion resistance of the joint, while keeping its mechanical performance.

Development of cathodic corrosion protection systems of nuclear ice breakers and arctic offshore structures

This article presents the results of the development and implementation of special ice-resistant anodes on nuclear icebreakers and offshore structures, capable of ensuring long-term effective cathodic corrosion protection systems under shock and abrasive effects of Arctic ice. The results of inspections of the hull and hull elements of the cathodic protection of the nuclear icebreaker “50 Let Pobedy” and the offshore ice-resistant platform “Prirazlomnaya” after their long-term operation are shown. Cathodic protection of the atomic icebreaker “Leader” has been described.

Bending Behavior of Zinc‐Coated Hot Stamping Steels

In the automotive industry, ultrahigh strength steels allow downgauging while, at the same time, passenger safety is increased. To expand the application fields of martensitic steels, which are frequently produced via hot stamping, cathodic corrosion protection is required. To date, zinc‐coated components are mainly processed via the detour of cold forming, but a precooling step to solidify all zinc phases prior to hot stamping shows great potential to overcome this limitation. Therefore, herein, directly quenched 22MnB5 is compared with an adapted alloy (20MnB8) after quenching with a precooling step. Bendability is used to assess the crash performance. In addition to the damage evolution, investigated via interrupted bending tests, a detailed microstructural analysis of the near‐surface region with respect to grain size, decaburization, inclusions, and other second phases is carried out. While 22MnB5 shows a fully martensitic microstructure, individual ferrite grains are observed within the martensitic matrix in the near‐surface region of 20MnB8. Carbon redistribution from ferrite to the surrounding martensite entails large hardness differences between the constituents as determined by nanoindentation, resulting in an earlier onset of strain localization and, therefore, decreased local formability.

Mathematical Modelling of Electric and Magnetic Fields of Main Pipelines Cathodic Protection in Electrically Anisotropic Media

A mathematical model is constructed and computational experiments are performed to study the effect of anisotropy of the specific electrical conductivity of the soil on the distribution of electric and magnetic fields generated by cathodic electrochemical corrosion protection stations of the underground main pipeline (MP). The variation of electric and magnetic fields depending on the azimuth angle of rotation of the specific electrical conductivity tensor of the soil containing the pipeline is analysed.

Cathodic Corrosion Protection of Steel with Electroplated Aluminum Alloys

Aluminum has excellent corrosion properties due to the formation of a dense oxide layer. This layer spontaneously forms in contact with air and protects the bulk material from further oxidation. Unfortunately, the formation of the natural oxide layer renders pure aluminum passive so that it is not a good candidate for the corrosion protection of a more noble substrate like steel. Therefore, for applications as a corrosion protection layer aluminum should be alloyed with other elements to prevent complete passivation.Electrodeposition is an elegant and cost-efficient method to apply thin coatings on various substrates with complex geometries. The layer properties can be easily controlled by adjusting the deposition parameters (current density, temperature, electrolyte composition). Aluminum cannot be deposited from aqueous electrolytes because of its negative Nernst potential (-1.66 V vs. NHE). Ionic liquids (ILs) are suitable electrolytes for the deposition of reactive metals, such as Al, Nb and Ta. They have a broad electrochemical window (> 3 V) and high electrical conductivity, and show good solubility for many metal salts.This paper will discuss the deposition of binary aluminum alloys from imidazolium-based ILs and their corrosion behaviour. Results from potentiodynamic polarization experiments will be compared with results from salt spray tests and long-term environmental exposure experiments (> 1 year) to assess the suitability of the alloys for cathodic corrosion protection of steel.

Research of efficiency of security of cathodic protection from corrosion for pipelines prepared for reconstruction with method «pipe in pipe»

The questions of organization of cathodic protection against corrosion of pipelines laid by the «pipe in pipe» method are considered. The variants of the organization of the cathodic corrosion system for pipelines laid by this method are determined. A laboratory stand simulating a pipe-in-pipe gasket with the installation of coppersulphate electrodes of comparison of small size between the pipes has been prepared. Laboratory studies to verify the protection of the main pipeline under various schemes of organization of cathodic corrosion protection were carried out. The conditions that must be observed when laying the pipeline to ensure the operation of the cathodic protection system, the main ones are the presence of electrolyte in the medium between the pipelines, as well as the absence of direct electrical contact between the pipelines. Negative features of joint protection of both pipelines are revealed. The optimal schemes of organization of cathodic corrosion protection during pipeline laying by this method, which are schemes with the use of extended anode grounding between pipelines or schemes without cathodic protection of external pipe, are determined. Solutions are proposed to eliminate the «failure» of the protective potential in contact with the metal between the pipelines, which consists in laying an extended anode grounding and local displacement of the potential of the internal pipeline relative to the external one.

SMART‐DECK: Multifunctional carbon‐reinforced concrete interlayer for bridges

AbstractThe service life of bridges is often threatened by an insufficient shear force capacity in the transverse direction as well as by leakages in the sealing layer, which leads to chloride ingress and therefore corrosion damages. To prevent expensive repair work and traffic obstructions, a thin, multifunctional interlayer of textile‐reinforced concrete called SMART‐DECK was developed. This interlayer provides three functions: A full‐surface moisture monitoring in real‐time, a preventive cathodic corrosion protection, and an increase of the shear force capacity. The operator of the bridge is able to monitor the condition of the sealer in real‐time. The relevant data are transmitted via the internet and show the condition of the sealer in a simple color scheme. If leakage occurs, the cathodic corrosion protection can be switched on to protect the reinforcement from corrosion damages. The renewing of the damaged bridge deck sealing has not to be carried out immediately but can be postponed over years, for example, to periods with little traffic. In this paper, the scientific approach for the realization of the system is presented, beginning with laboratory pretests on the materials and numerical simulations. The results are used to test the functions of the system in the laboratory and later on two demonstrators. An outlook will present the next research questions.

Surface conditions for microcosm development and proliferation of SRB on steel with cathodic corrosion protection

Steel components used in civil infrastructure are susceptible to microbiologically influenced corrosion (MIC) in marine environments due to the interactions between the metal and its environment with varying water quality parameters (chemical and biological). Sulfate-reducing bacteria (SRB) has been associated with MIC by a cathodic depolarization mechanism due to the reaction of surface hydrogen. Recent findings at a Florida bridge showed severe localized corrosion associated with microbial activity and heavy marine fouling of the submerged steel piles. Cathodic protection can be applied to control the corrosion of steel; however, the mitigation may be impaired by the microbial activity and marine fouling. The objective of this work was to explore reduction reactions on cathodically polarized steel surfaces and evaluate the influence of cathodic polarization on sulfate reduction reaction. It was of interest to characterize the reduction reaction in crevices representative of different physical properties of the marine foulers where SRB can be supported. Field testing was conducted to differentiate the cathodic protection currents that develop in the presence of microorganisms under the layer of marine fouling in natural environments. Laboratory tests were conducted to elucidate the cathodic reactions by potentiostatic cathodic polarization of steel specimens in solutions inoculated with SRB. Field testing showed that proliferation of the bacteria was not inhibited in the presence of cathodic polarization at about −1000 mVCSE and corrosion continued in the localized regions under fouling encrustation. The larger cumulative charge relating to the apparent sulfate reduction by SRB corresponded to higher levels of cathodic polarization. Sulfate reduction by SRB can be a significant contributor to the electrochemical process for steel corrosion with cathodic polarization. For the porous crevice environments, large cathodic currents and high sulfate reduction coincided with the development of sustained SRB growth.

Investigation of the Trivalent Chromium Process Conversion Coating as a Sealant for Anodized AA2024-T3

The sealing of an anodic coating on AA2024-T3 with a trivalent chromium process coating (TCP-HF) was investigated. Specimens were anodized in 9.8 wt% H2SO4 at 15 V DC (23 min) producing an oxide coating weight of ca. 1200 mg ft−2 and a thickness of ca. 5 μm. Elemental analysis revealed the sealant forms across the outer oxide layer and within the pores up to a depth at least approaching 1 μm. Anodic and cathodic currents in potentiodynamic polarization curves were suppressed by 5–10× and low frequency impedance (Z0.01 Hz) values were 5× higher for anodized specimens sealed with TCP (∼5 × 106 ohm-cm2), as compared to the unsealed anodized controls. During continuous exposure to 3.5 wt% NaCl, Z0.01 Hz values remained unchanged and greater than 106 ohm-cm2 after 5 days for the TCP-sealed specimen and decreased by 10× for the unsealed anodized control after just three days. A 14-day (336 h) neutral salt-spray exposure produced no significant pitting, discoloration or major coating detachment on anodized specimens sealed with TCP. Overall, the results indicate that the TCP sealant increases the barrier properties of the anodic coating and functions to provide anodic and cathodic corrosion protection.

Laboratory accelerated and field exposure testing of MgRP and MgORP on AA2024-T351: Chemical and electrochemical protection effects

Two Mg-based coatings consisting of Mg-rich primer (MgRP) and MgO-rich primer (MgORP) with and without topcoat were exposed to laboratory accelerated lifecycle testing (LALT) and outdoor field environments. The coatings were tested in parallel exposure studies utilizing ASTM B117, modified ASTM B117 (cyclic wet-dry, dark-UV exposure in ASTM synthetic ocean water), rural inland (Charlottesville, VA), and coastal marine (Kennedy Space Center) field exposure. Several characterization and electrochemical diagnostic techniques were used to continuously assess coating performance as a function of time in various exposures, enabling comparison of LALT to field exposures. The coating systems were evaluated with respect to the intact coating and to a machined scribe defect. The fate of Mg2+ upon dissolution of Mg and MgO with respect to pigment depletion, corrosion product formation, and repartitioning from the coating into the scribe was monitored with XRD and EDS. The capacity for MgRP and MgORP to provide barrier, cathodic, and chemical corrosion protection to AA2024-T351 substrate was evaluated. The ultimate ability of these coatings to protect the AA2024-T351 substrate both in the scribe and under the coating was gauged with optical profilometry assessment of corrosion damage. The Mg and MgO-based coating systems exhibited several desirable aspects of a corrosion preventative coating. The corrosion damage quantified both under the intact coating and within the scribe was much less than the corrosion damage measured on uncoated controls. Within a given exposure, the reduction of corrosion damage in the scribe correlated with the amount of Mg2+ which was released from the coating and repartitioned into the scribe. The open circuit potential of the coated substrate was depressed to more negative potentials than the bare substrate in 5 wt% NaCl, with non-topcoated samples establishing more negative potentials. The barrier properties remained high throughout the exposures for topcoated samples, which also better preserved the pigment from depletion. Comments are made regarding differences between the Mg and MgO-based coatings and the various laboratory and field exposures.