Insoluble Corrosion Products Research Articles

Corrosion resistance of zinc-magnesium-aluminium alloy coated steel in marine atmospheric environments

In this study, a salt-spray accelerated experiment was conducted as a simulated corrosion test of hot-dip galvanised zinc-magnesium-aluminium-coated alloy steel under a simulated marine atmospheric environment. In addition, scanning electron microscopy, confocal microscopy, X-ray diffraction, and electrochemical workstations were used to conduct analyses on the macro-morphology, microstructure, corrosion product composition, etc. after the corrosion test. Furthermore, the role of Mg in the corrosion resistance of zinc-magnesium-aluminium alloy steel sheets was determined. The research results indicated that in a marine atmospheric environment, zinc-aluminium-magnesium alloy steel has excellent corrosion resistance, and its external coating provides protection to the substrate. In a marine atmospheric environment, the corrosion products of zinc-magnesium-aluminium alloy steel mainly include Al2O3, AlOOH, zinc hydroxychloride (Zn5(OH)8Cl2·H2O), layered bimetallic hydroxides (Mg6Al2(OH)16CO3·4H2O), ZnO, and MgCO3·H2O. The addition of magnesium to galvanised sheets facilitates the formation of insoluble corrosion products, which protect the iron substrate.

Enhanced Long-Term Corrosion Resistance of 316L Stainless Steel by Multilayer Amorphous Carbon Coatings.

Diamond-like carbon (DLC) coatings are effective in protecting the key components of marine equipment and can greatly improve their short-term performance (1.5~4.5 h). However, the lack of investigation into their long-term (more than 200 h) performance cannot meet the service life requirements of marine equipment. Here, three multilayered DLC coatings, namely Ti/DLC, TiCx/DLC, and Ti-TiCx/DLC, were prepared, and their long-term corrosion resistance was investigated. Results showed that the corrosion current density of all DLC coatings was reduced by 1-2 orders of magnitude compared with bare 316L stainless steel (316Lss). Moreover, under long-term (63 days) immersion in a 3.5 wt.% NaCl solution, all DLC coatings could provide excellent long-term corrosion protection for 316Lss, and Ti-TiCx/DLC depicted the best corrosion resistance; the polarization resistances remained at ~3.0 × 107 Ω·cm2 after immersion for 63 days, with more interfaces to hinder the penetration of the corrosive media. Meanwhile, during neutral salt spray (3000 h), the corrosion resistance of Ti/DLC and TiCx/DLC coatings showed a certain degree of improvement because the insoluble corrosion products at the defects blocked the subsequent corrosion. This study can provide a route to designing amorphous carbon protective coatings for long-term marine applications in different environments.

A comparative study on the inhibition of microalgae attachment performance between Cu-based alloy laser cladding layer containing submicron Cr-rich precipitated phases and copper in simulated seawater

Copper alloys are prominent materials in ships and marine engineering structures due to their effective antifouling performance. However, the deposition of insoluble corrosion products dramatically deteriorates their antifouling performance during long-term immersion. To solve this conundrum, we have developed a novel Cu-based alloy cladding layer containing submicron Cr-rich precipitates, which aims to promote the corrosion products flaking through the effect of precipitates, thus effectively inhibiting microalgae attachment. After being immersed for 180 days, the coverage rates of microalgae on the cladding layer were below 2%, while those on the copper exceeded 40%. The remarkable inhibition of microalgae attachment achieved by the cladding layer is mainly due to the Cr-rich precipitates embedded in the unique and loose multi-layer structure corrosion product as Cr2O3-rich particles, which promotes the corrosion product cracking and flaking. Thereby, the cladding layer kills attached microalgae by increasing their reactive oxygen species (ROS) levels.

The Corrosion of Mn Coatings Electrodeposited from a Sulphate Bath with Te(VI) Additive and Influence of Phosphate Post-Treatment on Corrosion Resistance

Manganese coatings are excellent for the cathodic protection of steel against corrosion. Although manganese is more electrochemically active than widely used protective coatings of zinc, the exceptional resistance of manganese coatings in neutral and basic media is determined by the film of insoluble corrosion products, which forms on the surface of manganese and greatly suppresses its further corrosion. It is known that the electrodeposition process of Mn coatings from sulphate electrolytes is positively affected by some additives of chalcogenide (S, Se and Te) compounds in the electrolyte. However, a more detailed study on the corrosion properties of Mn coatings electrodeposited from sulphate bath with Te(VI) additive is lacking. In this work, the measurements of free corrosion potential and potentiodynamic polarization in a neutral NaCl solution, as well as the corrosion resistance properties of obtained Mn coatings, were evaluated in a salt spray chamber. It was obtained that the best corrosion resistance was shown by Mn coatings, electrodeposited at the cathodic current density of 15 A⋅dm−2 and at higher temperatures (60 and 80 °C). Meanwhile, the corrosion resistance of phosphated Mn coatings, obtained from a room temperature bath, increased about 5 times and reached up to 1000 h until corrosion of the steel substrate occurred.

Study on corrosion mechanism of Al–Zn coatings in the simulated polluted marine atmosphere

The corrosion behavior of Al–Zn coatings on steel sheets in simulating polluted marine atmosphere was systematically evaluated by weight loss tests, potentiodynamic polarization curves, electrochemical impedance spectroscopy, and acid salt spray test. The results demonstrated that the AI-Zn coating produced a passivation film of Al2O3 with good corrosion resistance, forming a thick and dense layer of insoluble corrosion products. In addition, the corrosion products such as Zn5Cl2(OH)8·H2O and NaZn4(SO4)Cl(OH)6•6H2O hindered the diffusion of corrosive substances into the coating and thus inhibited further corrosion.

Corrosion behavior and passive film properties of nickel-based alloy in phosphoric acid

Corrosion behavior and passive film properties of nickel-based alloy (Inconel 625) in phosphoric acid were investigated, by means of a variety of electrochemical methods combined with surface analysis techniques. Results showed that Inconel 625 exhibited strong passive behavior in phosphoric acid but their corrosion resistance was deteriorated with increasing concentration of phosphoric acid. The increasing concentration of phosphoric acid also accelerated the corrosion rate. The passive film of Inconel 625 was composed of an inner layer rich in Cr2O3 and an outer layer rich in FeOOH. The initial corrosion of Inconel 625 in phosphoric acid originated from the complex inclusions composed of N, Nb and Ti with a corn rich in Mg and O. At concentrations lower than 1 mol/L, inner layer of the passive film remained intact and only the outer layer was damaged. At concentrations of phosphoric acid higher than 1 mol/L, both the inner and outer layers were destroyed. The insoluble corrosion products Fe phosphate compounds precipitated on the surface of Inconel 625, which accumulated with increasing concentrations of phosphoric acid and became a loose layer covering the surface of Inconel 625 at concentrations of phosphoric acid higher than 1 mol/L.

Study on combustible gas generation and radionuclide release during underwater handling of the AM reactor spent fuel

Introduction. The paper addresses studies on the accumulation of combustible gases during underwater handling simulations for the leaky spent nuclear fuel from the AM reactor. Two fuel compositions were studied- uranium-molybdenum dispersed in magnesium and uranium carbide dispersed in calcium. Methods. The 137Cs release rate was measured during underwater storage of the uranium-molybdenum fuel. The kinetics of hydrogen release for both fuels and methane release for the carbide SNF were obtained. The kinetics approximate most with exponential dependences that formally correspond to first-order chemical reactions. A contribution of radiolytic hydrogen to the gases generated during the experiments was estimated. It was demonstrated that the determining source of the gases is the chemical interaction between the spent fuel and the water. The experiment with the uranium-molybdenum fuel demonstrated a pronounced passivation effect of the chemical processes on the fuel surface due to insoluble corrosion products. For the carbide SNF, an incubation period of about 20 hours was observed followed by an intensive release of hydrogen and methane. Results. The obtained results were subject to a comparative analysis against publications on the behavior of the fuel components in water. Conclusion. The findings can be applied to justify fire and explosion safety of underwater handling techniques for the damaged spent nuclear fuel with the considered fuel compositions (the spent fuel from reactors AM, AMB, EGP-6, etc.), e.g., to justify underwater preparations of the AMB spent fuel for reprocessing.

Effect of microstructural evolution and texture change on the in-vitro bio-corrosion behaviour of hard-plate hot forged Mg-4Zn-0.5Ca-0.16Mn (wt%) alloy

The synergistic influences of particle stimulated nucleation (PSN)-assisted dynamic recrystallisation (DRX), second-phase particles and texture on corrosion behaviour of hard-plate hot forged Mg-Zn-Ca-Mn alloy are studied in Kirkland’s bio-corrosion medium. The particle-matrix interfaces and grain boundaries are more anodic and act as effective sites for corrosion initiation and insoluble corrosion product layer formation. Consequently, the uniform and compact product layer is formed in the specimen with higher DRX fraction, uniform particle distribution and smaller deformed grains. The uniform corrosion product layer and higher basal texture intensity lowered the pH change, hydrogen evolution and corrosion rate during the long-term immersion test. Data availability statementThe raw data related to this manuscript would be made available on request.

Pore colmatation in case of liquid corrosion of concrete

Pore colmatation plays a positive role, since a decrease in the permeability of cement concrete due to the deposition of insoluble corrosion products in the pores leads to a slowdown in corrosion processes. To test a mathematical model of pore colmatation of cement concretes under liquid corrosion, a study of mass transfer processes occurring when samples from Portland cement are exposed to a liquid aggressive medium was conducted. The article presents equations that allow us to determine the rate of pore colmatation and the thickness of the layer of colmatant formed in the pores during liquid corrosion of cement concretes. Based on the results of experimental studies of liquid corrosion of cement stone, the mass transfer parameters were determined in the investigated system «cement concrete – 2 % MgCl2 solution». Based on the obtained data, the values of the colmatation rate and the thickness of the layer of colmatant of cement concrete were calculated during liquid corrosion in a 2 % MgCl2 solution. It has been established that over time, the rate of mass transfer processes occurring in concrete decreases due to the difficulty of penetration of aggressive medium deep into concrete due to the deposition of corrosion products in the pores.

Electrodeposition of Zinc from Alkaline Electrolytes Containing Quaternary Ammonium Salts and Ionomers: Impact of Cathodic‐Anodic Cycling Conditions

AbstractDendrite suppression capabilities are key factors for the practical deployment of rechargeable Zn‐based batteries. We propose a systematic electrochemical investigation, accompanied by SEM imaging, of the impact of representative quaternary ammonium (QA) salts and ionomers on Zn electrodeposition. Both cathodic and anodic processes were considered, because insoluble corrosion products can impact subsequent electrodeposition during cycling. We used simple cyclic voltammetry methods and developed a framework for their quantitative interpretation in terms of physically legible descriptors. QA‐based additives tend to suppress the accumulation of anodic products, favoring symmetric cathodic and anodic activation. Poly di‐allyl di‐methyl ammonium chloride (PDADMAC), a polymer with limited cathodic reactivity, was found to be a promising additive that minimizes cathodic and anodic irreversibility and stabilizes mass transport, possibly owing to the formation of a single‐ion conducting cathodic film.

Characterization and Biocompatibility of Insoluble Corrosion Products of AZ91 Mg Alloys.

Biodegradable Mg alloys have good bioactivity and suitable mechanical properties, which is desirable for application in the clinical fields. However, the biocompatibility of Mg alloys during the degradation process has always been a concern. In this paper, the corrosion behavior of AZ91 alloys in a simulated cell culture environment was studied, especially the insoluble corrosion product during the degradation was characterized, and the biocompatibility of the insoluble corrosion products was evaluated. The results of immersion test showed that the corrosion rate of the AZ91 alloy was low under the condition of high CO2 and humidity, especially in phosphate-buffered saline. Moreover, the insoluble corrosion product was MgCO3·3H2O, which showed a needle-like, circular aggregated, and square-radial feature. Meanwhile, MgCO3·3H2O showed poor cell biocompatibility by increasing the pH and Mg2+ content of the culture solution, which may affect the biocompatibility of Mg alloys.

Analysis of the Causes of Tube and Pipeline Blocking in Sulige Gas Field

A large number of blockage appeared in gas wells and pipeline appeared, which causedplugging, corrosion and the increasing of wellbore pressure difference, and seriously affect thenormal production of gas well of problems. In this paper, the water quality of produced water fromthe severe cases of single wells or pipeline water were analyzed, also include the composition ofblockage and core with the chemical volumetric method (CVM) , X-Ray Diffraction (XRD) and x-rayfluorescence (XFS) method. Meanwhile, the core powder was leached in simulated acid worksolution, and then the leaching solution was analyzed with CVM. The experimental results show thatThe produced water has high salinity, high contents of Ca2+, Ba2+ and Sr2+, low pH value, which leadto corrosion and scaling. The main components of the blockage are acid insoluble strontium sulfate(barium) scale or corrosion product or mixture of corrosion and CaCO3 scaling product. Ca2+, Ba2+and Sr2+ were easy to scale in wellbore or pipeline when they encountered other produced water fromdifferent formation. The Ca2+, Mg2+, Ba2+, Sr2+ and Fe 2+/3+ mainly derived from the dissolution offormation debris in formation water and working fluid (especially acidic working fluid) to reservoirrock, so the salinity of the produced water increased, and the trend of scaling and corrosion alsoincreased with the gas field development.

Modeling the effect of insoluble corrosion products on pitting corrosion kinetics of metals

Most metals naturally corrode in an engineering environment and form corrosion products. The corrosion products can be either soluble or insoluble in the aqueous solution. The insoluble corrosion products (ICP) could have profound effects on the corrosion kinetics of the concerned metal. In this study, a multi-phase-field formulation is proposed to investigate the effects of ICP formation on pitting corrosion kinetics. The Gibbs free energy of the metal-electrolyte-insoluble corrosion product system consists of chemical, gradient, and electromigration free energy. The model is validated with experimental results and several representative cases are presented, including the effect of the porosity of ICP, under-deposit corrosion, corrosion of sensitized alloys, and microstructure-dependent pitting corrosion. It is observed that corrosion rate and pit morphology significantly depend on ICP and its porosity for the same applied potential.

In vitro investigation of cellular effects of magnesium and magnesium-calcium alloy corrosion products on skeletal muscle regeneration

Biodegradable magnesium (Mg) has garnered attention for its use in orthopaedic implants due to mechanical properties that closely match to those of bone. Studies have been undertaken to understand the corrosion behaviour of these materials and their effects on bone forming cells. However, there is lack of research on how the corrosion of these biomaterials affect surrounding tissues such as skeletal muscle. Mg plays an important role in the structural and functional properties of skeletal muscle. It is therefore important to investigate the response of skeletal muscle cells to both soluble (Mg ions) and insoluble (corrosion granules) corrosion products. Through in vitro studies it is possible to observe the effects of corrosion products on myotube formation by the fusion of single muscle precursor cells known as myoblasts. To achieve this goal, it is important to determine if these corrosion products are toxic to myotubes. Here it was noted that although there was a slight decrement in cellular viability after initial exposure, this soon recovered to control levels. A high Ca/Mg ratio resulted in the formation of large myotubes and a low Ca/Mg ratio negatively affected myotube maturation. Mg2+ and Ca2+ ions are important in the process of myogenesis, and the concentration of these ions and the ratio of the ions to each other played a significant role in myotube cellular activity. The outcomes of this study could pave the way to a bio-informed and integrated approach to the design and engineering of Mg-based orthopaedic implants.

Corrosion protection of steel cut‐edges by hot‐dip galvanized Al(Zn,Mg) coatings in 1 wt% NaCl: Part I. Experimental study

Corrosion of AlZnMg coated steel in chloride media is a complicated process, which progress is determined not only by the electrode reactions but also by the local pH and formation of soluble and insoluble corrosion products. In order to adequately describe and predict the corrosion behavior of steel/AlZnMg cut‐edge, a multi‐ion transport, and reaction model (MITReM) is built. Such model takes into account the transport of species in the solution together with their production/consumption in electrochemical and chemical reactions. The main aim of this work is the validation of a numerical model for describing and predicting corrosion of steel/AlZnMg cut‐edge in immersed conditions. This first part describes the experimental work done to obtain model input parameters and validation measurements. The metallic coatings are characterized experimentally with respect to their composition and microstructure, global and local electrochemical behavior (polarization curves, AESEC, and SVET). Local distribution of corrosion products and local pH are also characterized. No blocking effect of the precipitated corrosion products has been observed and dedicated measurements are performed to validate this observation. Based on the experimental input from this part, numerical models of cut‐edge corrosion with different levels of details are developed in Part II.

Influence of Hydrogen Sulfide on the Corrosion-Electrochemical Properties of 20 Steel with Coatings Based on Zinc and Aluminum

We study the corrosion of a hot-dip zinc coating and arc-sprayed aluminum and zinc coatings in chloride- acetate solutions and model seawater saturated with hydrogen sulfide. It is shown that, in chloride–acetate solutions, hydrogen sulfide promotes an increase in the corrosion rate of 20 steel by more than an order of magnitude. For the hot-dip zinc coatings, hydrogen sulfide does not change the corrosion rate, whereas for the arc-sprayed coatings, it decreases the corrosion rate by a factor of ∼ 5. The saturation of model seawater with hydrogen sulfide decreases the corrosion rate of 20 steel by a factor of ∼ 7 and the corrosion rate of the hot-dip zinc coating by a factor of ∼ 1.4 but does not affect the corrosion rate of the arc-sprayed coating. The insoluble corrosion product of zinc, namely, its sulfide, does not passivate these coatings. Hydrogen sulfide leads to an insignificant increase in the corrosion rate of the arc-sprayed aluminum coating both in a chloride–acetate solution and in model seawater. Its values are 3–7 times lower than for 20 steel, which indicates the possibility of application of the coatings based on aluminum for the corrosion protection of steels in hydrogen-sulfide-containing media.

High Magnesium Corrosion Rate has an Effect on Osteoclast and Mesenchymal Stem Cell Role During Bone Remodelling

The aim of this study was to gain an understanding on the collective cellular effects of magnesium (Mg) corrosion products on the behaviour of cells responsible for bone formation and remodelling. The response of mesenchymal stem cells (MSCs) and osteoclast cells to both soluble (Mg ions) and insoluble (granule) corrosion products were recapitulated in vitro by controlling the concentration of the corrosion products. Clearance of corrosion granules by MSCs was also inspected by TEM analysis at sub-cellular level. The effect of Mg corrosion products varied depending on the state of differentiation of cells, concentration and length of exposure. The presence of the corrosion products significantly altered the cells’ metabolic and proliferative activities, which further affected cell fusion/differentiation. While cells tolerated higher than physiological range of Mg concentration (16 mM), concentrations below 10 mM were beneficial for cell growth. Furthermore, MSCs were shown to contribute to the clearance of intercellular corrosion granules, whilst high concentrations of corrosion products negatively impacted on osteoclast progenitor cell number and mature osteoclast cell function.

Patina enrichment with SnO2 and its effect on soluble Cu cation release and passivity of high-purity Cu-Sn bronze in artificial perspiration

The antimicrobial function of Cu surfaces can be linked to soluble Cu release from corrosion. However, direct replacement of high-touch surfaces with Cu-based alloys is limited by knowledge gaps regarding how alloying directly relates to corrosion. A systematic approach to determine the role of Sn as a solute element and the minimum alloy content for passivation has been lacking. High-purity arc-melted binary alloys of Cu-Sn with specific additions of 0.1, 1, 5, and 10 wt% Sn were compared to pure Cu and Sn. The role and amount of Sn in corrosion products (patina) formed on the alloy surface as a function of alloying was interrogated in artificial perspiration. The fate and identity of the solute (Sn) and solvent (Cu) elements following corrosion, as soluble ions or insoluble corrosion products, was investigated. Alloy patinas became increasingly enriched in Sn corrosion products identified as SnO2 with increasing Sn content in the alloy. The critical alloy content for complete SnO2 layer coverage were theoretically quantified through a model based on interfacial surface energy. The predicted minimum solute content for a complete conformal inner layer of SnO2 was 1 wt% Sn whereas experimentally complete coverage was achieved only at 10 wt% Sn. Differences between theory and experiment are discussed.

The replacement of chromate by molybdate in phosphoric acid-based etch solutions for aluminium alloys

ABSTRACTCorrosion inhibition of aluminium alloys in the acidic solutions is important in the aluminium finishing industry (stripping solutions for anodic films). Sodium molybdate is a potential replacement for chromate-containing species used in the stripping solutions. It was tested as the corrosion inhibitor of 2024 aluminium alloy in orthophosphoric acid solutions. A corrosion rate of the alloy as a function of an initial concentration of sodium molybdate and temperature was determined by using gravimetric and gasometric methods. The corrosion rate was significantly lower in the solutions containing over 5 mM of sodium molybdate when compared to the uninhibited solution. The inhibition efficiency decreased with the increase of the temperature for the constant concentration of sodium molybdate. Sodium molybdate reduced the corrosion of the alloy by adsorption as well as formation of insoluble corrosion products on the alloy.

Is there any difference in the biological impact of soluble and insoluble degradation products of iron-containing biomaterials?

The interactions that could be built between the biomaterials and tissue- microenvironments are very complex, especially in case of degradable metals that generate a broad variety of degradation products. The interfacial problems are particularly relevant for Fe-based materials that have been proposed for the development of biodegradable implants. The cell metabolism could be affected by the accumulation of insoluble Fe-containing degradation products that has been observed in vitro and in vivo as a coarse granular brownish material around the implant. However, the relative importance of each Fe-species (soluble and insoluble) on the cellular behavior of the surrounding cells, particularly on the generation of reactive species (RS), is not completely elucidated.The aim of this study is to evaluate the processes occurring at the Fe-biomaterial/cells interfacial region, and to discriminate the effects of soluble and insoluble corrosion products released by the bulk metal (Fe- microparticles (Fe0p) or Fe0 ring) on the adjacent cells, mainly in relation to RS generation.With this purpose Fe0p and Fe0 ring were incubated with fibroblast cells (BALB/c 3T3 line) for 24 and 48h periods. Then different techniques were used, such as the dichlorofluorescein diacetate assay (DCFH2-DA) for detection of RS, acridine orange dye for cell viability, total protein content determinations, Prussian Blue staining and TEM observations. To individualize the effects of soluble and insoluble species, independent experiments with Fe3+-salts were performed. Overall data indicate that RS generation by cells exposed to the degradation products of Fe-based biomaterials is more dependent on the presence of insoluble products than on soluble Fe species.