Corrosion Stability Research Articles

Effective Waterproofing of Railway Culvert Pipes

The composition material for waterproofing of the railway infrastructure objects, in particular, culvert pipes is suggested in the article. The waterproof composition contains an acrylic polymer and a filler. The comparison of the composition properties with two kinds of the fillers (silica sand and Portland cement) is carried out. The following properties are defined – water absorption, corrosion stability, stability in an aggressive environment, frost resistance to evaluating the suitability of the proposed composition for waterproofing. These properties are determined for three batches: an acrylic polymer without a filler, an acrylic polymer with silica sand, and an acrylic polymer with Portland cement. The test results show that the composition with silica sand possesses the best waterproofing properties. Wherein the quantity of silica sand is 1.5 mass parts to the quantity of polymer. Compared to the non-filled acrylic polymer the offered composition is characterised less water absorption, more significant corrosion stability and stability in an aggressive environment, better frost resistance. The mix with Portland cement shows a bit worse results at a higher cost of the material in whole.

Surface treatments and functionalization of metal‐ceramic membranes for improved enzyme immobilization performance

AbstractBACKGROUNDEnzyme immobilization in porous membranes often improves enzyme performance. This work reports the preparation and characterization of robust and scalable asymmetric metal‐ceramic microfiltration membrane. The surface of the porous metal‐ceramic membrane was treated by impregnation with a ceramic oxide for enzyme adsorption and corrosion protection. Finally, enzyme immobilization in the support was investigated.RESULTSThe bilayer membrane was successfully fabricated by combining a ceramic microfiltration layer with a metal support by tape casting, lamination and co‐sintering. A pore size in the ceramic microfiltration layer of 0.4 μm resulted in high water permeability (12 000 L/(m2 h bar)). Two different surface treatments were compared: heat treatment and yttrium(III) oxide (Y2O3) impregnation. Corrosion stability tests under enzyme‐relevant conditions gave no detectable chemical or structural changes. Alcohol dehydrogenase (EC 1.1.1.1) was immobilized in the membrane by physical adsorption and by two covalent immobilization methods. Covalent immobilization significantly improved enzyme loading, activity, and recyclability. Membrane reuse by heat treatment removed fouling, but decreased immobilization performance.CONCLUSIONThe improved microstructure obtained by Y2O3‐impregnation had a significant effect on enzyme loading yield and activity. This indicates the potential of this surface modification method and of these metal‐supported ceramic membranes in enzyme immobilization. Covalent immobilization was superior. © 2019 Society of Chemical Industry

Corrosion and Thermal Stability of CrMnFeNi High Entropy Alloy in Molten FLiBe Salt

The corrosion behavior of the FCC Cr18Mn27Fe27.5Ni27.5 high entropy alloy (HEA) after exposure to molten FLiBe salt at 700 °C for 1000 hours, has been investigated. Results show that the HEA lost a higher mass compared to the reference 316 H stainless steel due to the dissolution of Mn into the molten salt. The loss of Mn from the alloy appeared to discourage the dissolution of Cr in the molten fluoride salts which is widely recognized as the mechanism of corrosion degradation. Thermal exposure at 700 °C for 1000 hours also led to the precipitation of an additional BCC phase Cr67Fe13Mn18.5Ni1.5, which was confirmed by CALPHAD predictions.

Multi-factor Comprehensive Evaluation on Durability of Various Grouting Materials

With In this paper, four grouting materials, namely new type grouting material, pure cement, cement-sodium silicate and glue sand, were tested by single factor for their water corrosion resistance, permeability resistance and volume stability. The durability of the four grouting materials under the environment of three factors was evaluated by the multi-factor fuzzy comprehensive evaluation method. The results show that the three kinds of new type grouting materials are better than the other three kinds of grouting materials in terms of anti-water corrosion and volume stability. In terms of impermeability, the performance of cement reached the best impermeability pressure of 0.8Mpa, but the impermeability pressure of new type grouting material with a water-cement ratio of 1.0 has also reached 0.6MPa, which can meet the impermeability requirement with a small gap with cement. As a scientific and effective evaluation method, the method will be helpful to the further study of the durability of grouting materials.

Effect of nitrogen-doping on the surface chemistry and corrosion stability of TiO2 films

TiO2 and N-doped TiO2 films were grown on AISI 316 stainless steel substrates and on Si (100) by metallorganic chemical vapor deposition (MOCVD) at 400°C and 500°C. X-ray photoelectron spectroscopy, scanning electron microscopy, and contact angle techniques were used to characterize de films. The corrosion behavior was assessed by monitoring the open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization tests in 3.5wt% NaCl solution at room temperature. The results show that 6.18 at% of nitrogen was introduced in the films grown at 400°C and 8.23 at% at 500°C, and that besides TiO2, nitrogen phases were identified. All the films are hydrophilic and the contact angles varied from 48° to 72°. The films presented good homogeneity, low porosity and rounded grains in the range of 40–90nm. The RMS roughness varied between 5.5 and 18.5nm. Titanium dioxide films grown at 400°C showed better corrosion resistance than those grown at 500°C due to its compact morphology. Nitrogen-doping was not efficient to protect the substrate from corrosion.

Research of corrosion stability of steel brand 12X18H10T and titanium brand ВT1–0 for solder baths

General global trend of reduce the proportion of physical experiment when designing equipment led to an increase in the significance of the calculation and to tighten the requirements for its conduct. The study was carried out corrosion resistance of steel brand 12X18H10T and titanium brand ВT1–0 for solder baths. Based on the experiments of corrosivity was concluded that preparing the metal surface of the solder baths is a determining factor. Corrosion of the samples was uneven over the entire surface, the main corrosivity is manifested during the first 50 hours. Further etching of the samples leads to a slow decrease in the corrosion rate with the exit to the plateau. Thanks to this study, it has been established that steel brand 12X18H10T and titanium brand ВT1–0 are acceptable structural materials and are proposed for use in mass production.

Mathematical modelling of heat-resistant nickel alloys high temperature corrosion

The mathematical modelling of the average corrosion rate () or nickel alloys with different alloying systems (for mono-, directed- and equilibrium crystallization) under synthetic ash conditions at different temperatures has been carried out. Since modern heat-resistant nickel alloys have complex multicomponent compositions, in which all the elements influence on corrosion complexly, the high temperature corrosion (HTC) stability was evaluated by the value of the known parameter Pks(surface resistance coefficient). This made it possible to compare the level of stability of alloys with different alloying schemes. However, this parameter does not cover all the alloying elements that are present in the heat-resistant nickel alloys. Therefore, as a result of analysis and processing of experimental data, the ratio of alloying elements to assess the corrosion resistance has been proposed; this ratio considers the complex influence of the main components of the alloy. Since high temperature corrosion (HTC) is related to the presence of certain elements in the alloy and their concentration, the ratio Kps (surface resistance coefficient) makes it possible to evaluate more adequately the average corrosion rate at different temperatures for multi-component nickel systems. The dependence of the average corrosion rate on Kps for monocrystalline alloys is straightforward, due to the specific character of the alloying systems of this class materials. Characteristic for them is a significantly less amount of chromium (up to 10% by weight) is characteristic of them and a decrease in the content (and in some alloys, absence) of titanium as well, which results in a significant reduction in the high temperature corrosion (HTC)-stability of the material. It has been established that to ensure the required level of high temperature corrosion (HTC) stability of alloys of directed and equilibrium crystallization, the value of the ratio should be not less than Kps ≥ 2, which will provide a non-destructive dense film of corrosion products. So, for the alloys with Kps ≤ 2 the formation of a thick layer of corrosion products, which is easily separated during the operation is characteristic. The obtained regression models give an opportunity to predict the average speed of corrosion depending on the alloying system, both for the development of new heat- resistant nickel alloys for directed crystallization, and in improving the composition of the known industrial alloys within the brand composition. The obtained correlation dependencies are exponential in nature

One-Stage Calcium Carbonate Oil-Based Filter Cake Removal Using a New Biodegradable Acid System

Removal of the oil-based filter cake is a complex task especially in horizontal and multilateral wells. The presence of oil makes the removal process more challenging because the oil coats the weighting materials and prevents acid–filter cake interaction. Therefore, different additives are required to change the wettability of the filter cake to enhance the removal efficiency. This paper introduces a new biodegradable acid system (NBAS) that can efficiently remove oil-based filter cake in horizontal and multilateral wells where calcium carbonate is used as a weighting agent. The new biodegradable acid system (NBAS) consists of 50 vol.% biodegradable acid and 5 vol.% mutual solvent, and the remaining percent is deionized water. High-pressure high-temperature (HPHT) filtration experiments were performed to evaluate the filter cake removal efficiency and the retained permeability. The filtration and removal experiments were conducted using real core samples (Indiana limestone and Berea sandstone) at a temperature of 212 °F and 300 psi differential pressure. Afterward, the NBAS was evaluated by measuring physical properties and conducting corrosion, compatibility, and thermal stability studies. The obtained results showed that the NBAS was compatible and thermally stable for more than 48 h at 212 °F and 300 psi. The NBAS has a density of 1.05 g/cm3, viscosity of 1.47 cP, and surface tension of 32 dynes/cm at room temperature. The corrosion rate of the developed system was 0.03 lb/ft2, which is acceptable according to oil and gas industry best practices. Removal experiments showed that the filter cake was completely removed from the core samples. For Berea sandstone, 100% of the permeability was regained, while the retained permeability for Indiana limestone was 122.5%, confirming the complete removal of external and internal filter cake as well as core samples stimulation. The new acid system can be considered as an efficient solution for oil-based filter cake removal that is biodegradable and cost-effective, where the reservoir permeability can be regained in one-stage only.

Electrochemical Deposition of Mixed Ce-Al Oxide Layers on Stainless Steel and Assessment of their Corrosion-Protective Ability

The corrosion protective ability of the electrodeposited mixed nanocrystalline (CeO2)x(Al2O3)1-x layers has been studied in 0.1M HNO3 solution as a function of the changing ratio between CeO2, CeAlO3 and Al2O3 on the modified SS surface. It was ascertained that the mixed layer changes substantially the character of the cathodic corrosion reaction, which leads to changes in the control of the corrosion process and stabilization of the passive state of the SS, the system (CeO2)x(Al2O3)1-x/SS respectively, in case of prolonged corrosion testing.

Investigation of corrosion behaviour of carbon nanotubes coated basalt fabric as a reinforcement material

In this study, the corrosion behaviour of carbon nanotubes (CNTs) coated basalt fibre (BF) (BFCNTs) obtained by chemical vapour deposition (CVD), was studied. During CVD, the CNTs were grown on BF, (a) at different growth temperatures and (b) for different growth times. The physicochemical measurements were performed using X-ray diffraction, Raman spectroscopy, and field-emission scanning electron microscopy. The corrosion performances were investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic sweep (PDS), linear polarization resistance (LPR) and weight loss measurements. The BFCNT prepared at 650 °C for 120 min exhibited the best corrosion stability during the prolonged exposure to 0.1 M NaCl electrolyte. The outcomes of this study would be useful in designing the carbon nanotubes coated basalt fibre with the best corrosion resistance.

Short- and Long-Term Wettability Evolution and Corrosion Resistance of Uncoated and Polymer-Coated Laser-Textured Steel Surface

We present the results of one year observation of wetting and corrosion properties of nanosecond fiber laser-textured stainless steel, uncoated and coated with epoxy or FAS (fluoroalkylsilane)-TiO2/epoxy. A comparative study was performed on samples kept under ambient conditions and in reduced air pressure and humidity. The results show the ability to induce wettability conversion from initially superhydrophilic to final superhydrophobic state either indirectly by ageing the uncoated laser-textured surface or directly by application of FAS-TiO2/epoxy coating. The storage conditions significantly influenced the wettability development of uncoated laser-textured steel, i.e., the process of ageing was slowed down in reduced air pressure and humidity. Detailed surface chemical analysis revealed that adsorption of the organic matters from the surrounding media influences the wettability conversion and ageing. However, the ageing of the coated surfaces was not affected by the storage conditions. Corrosion stability of uncoated laser-textured surfaces was enhanced over time due to the wettability transition, depending on their morphology. Coatings represent a superior barrier over the texture and wettability with the stable long-term surface protection against aggressive media.

Study of corrosion stability of a cement stone in magnesia aggressive environment

One of the main tasks in the construction of oil and gas wells is to ensure the high quality of well casing. It is especially difficult to get it in wells, in sections of which there are salt-bearing strata. From the salts, the most dangerous are magnesia salts, which can lead to the destruction of the stone based on portland cement within a few months. The report presents the results of experimental studies on the corrosion of cement stone in aggressive magnesia media.The quantitative indicators reflecting the degree of damage to the stone are taken as the thickness of the damaged layer and the coefficient of stone resistance, characterized by the ratio of the ultimate strength of stone samples for compression or bending stored in an aggressive environment to the strength of control samples at the same time of hardening. In the course of the research, the corrosion resistance of the cement stone to the magnesian corrosive environment was assessed, after 8 weeks in a medium with a constant concentration of MgCl2. In addition, the effect of MgCl2 concentration on the cement stone corrosion mechanism was investigated. The use of the palygorskit additive and the reduction of water cement ratio to reduce the porosity of the cement stone and reduce the rate of corrosion damage are proposed. The kinetics and the main factors affecting the corrosion process are considered, and the x-ray structural analysis of corrosion products and unaffected cement stone is carried out.

Compo­sition, structure and properties of electroless deposited nickel – phosphorus – copper coatings

The nickel – phosphorus – copper functional coating was deposited on aluminum alloys substrate by chemical deposition method from malonate­glycinate nickel plating solution. The chemical and phase coatings composition was studied by X­ray fluorescence and X­ray phase analyze. Thermally stimulated phase transitions in deposited Ni – P – Cu coating were detected by differential scanning calorimetry method. The annealing at 250 and 400 °С was shown to lead to the changes in coating structure involving the transition from amorphous to amorphous­crystalline at 250 °С and to crystalline at 400 °С with Ni and Ni3P1 – δ phases forming. Changes in the structure of Ni–P coating results in the increase of microhardness by 1.6–1.7 times and wear resistance by 3– 4 times. Annealing at 400 °С led to decreasing of corrosion stability of the coatings in 3.5 % sodium chloride solution. The optimum physical, mechanical and protective properties has the attained in the case of Ni – P – Cu coating annealed at 250 °C.

Hydrogen gas production with Ni, Ni–Co and Ni–Co–P electrodeposits as potential cathode catalyst by microbial electrolysis cells

The development of efficient and economical cathode, operating at ambient temperature and neutral pH is a crucial challenge for microbial electrolysis cell (MEC) to become commercialize hydrogen production technology. In the present work, eight different electrodes are prepared by the electroplating of Ni, Ni–Co and Ni–Co–P on two base metals i.e., Stainless Steel 316 and Copper separately to use as cathode in MEC. Electrodeposited cathode materials have been characterized by XRD, XPS, FESEM, EDX and linear voltammetry. The fabricated cathodes show higher corrosion stability with improved electro-catalytic performance for the hydrogen production in the MECs as compared to the bare cathodes (SS316 and Cu). Data obtained from linear voltammetry and MEC experiments show that developed cathode possess four times higher intrinsic catalytic activity in comparison to bare cathode. Electrodeposited cathodes are intensively examined in membrane-less MEC, operating under applied voltage of 0.6 V in batch mode at 30 ± 2 °C temperature, in neutral pH with acetate as substrate and activated sludge as inoculum. Ni–Co–P electrodeposit on Stainless Steel 316 cathode gives maximum hydrogen production rate of 4.2 ± 0.5 m3(H2)m−3d−1, columbic efficiencies 96.9 ± 2%, overall hydrogen recovery 90.3 ± 4%, overall energy efficiency 241.2 ± 5%, volumetric current density 310 ± 5 Am−3. The net energy recovery and COD removal are 4.25 kJ/gCOD and 61%, respectively. Prepared cathodes show stable performance for continuous 5 batch cycle operations in MEC.

Application of Scanning Kelvin Probe in the Study of Protective Paints

Industrial coatings are composed of layers of different polymers (top coats, primers) containing pigments, corrosion inhibitors, and fillers as well as additives. For corrosion protection, it is vitally important to preserve the strong adhesion and long-term stability of the metal-polymer interface in corrosive environments. In recent decades, the performance of painted materials increased, which requires the application of advanced methods for quick assessing, ranking and predicting corrosion stability. Scanning Kelvin probe (SKP) is a highly sensitive and non-invasive technique to analyze in situ the metal-polymer interface of high-performance industrial coatings. SKP is able to monitor the adhesion and corrosion underneath different kinds of paints without the need for long-term corrosion tests. SKP is a localized electrochemical technique with a spatial resolution in the range of 70-100 µm. Hence, it is possible to obtain information about the intact and corroding portions of the interface at defect sites, corrosion blisters, contaminants and intermetallics, quality of pretreatments, and the development of galvanic couples that lead to corrosion de-adhesion of the polymeric coatings. This article reviews the application of SKP to the determination of the mechanisms of corrosion de-adhesion of model paints, thick marine paints, coatings with zinc rich primers, automotive paints and coil coatings applied on galvanized steel substrates.

The effect of ceria and zirconia nanoparticles on the corrosion behaviour of cataphoretic epoxy coatings on AA6060 alloy

In this work an attempt was made to produce epoxy coating doped with ceria (CeO2) and/or zirconia (ZrO2) nanoparticles, in single step electrophoretric deposition process. Deposition was carried out on AA6060 cataforetically from epoxy resin suspension containing synthesized stable aqueous colloidal dispersions (sols) of CeO2 and ZrO2. The influence of ceria and zirconia nanoparticles on the physicochemical characteristics of epoxy coatings was evaluated by energy dispersive X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis and adhesion measurements, while their corrosion stability during immersion in 0.5 M NaCl solution was monitored by electrochemical impedance spectroscopy. All ceria and/or zirconia containing coatings showed better corrosion stability and adhesion than pure epoxy coating, while between doped epoxy coatings one with CeO2/ZrO2 exhhibited the greatest values of charge-transfer resistance due to synergetic effect of both types of added nanoparticles.

The influence of the surface nanostructured modification on the corrosion resistance of the ultrafine-grained Ti–13Nb–13Zr alloy in artificial saliva

On the surface of the ultrafine-grained Ti–13Nb–13Zr alloy and the coarse-grained Ti–13Nb–13Zr alloy nanotubular oxide layers were formed by electrochemical anodization in the 1 M H3PO4 + NaF electrolyte in order to evaluate the electrochemical behaviour in the artificial saliva. SEM images showed that homogeneous nanotubular oxide layers could be formed by anodic oxidation of titanium alloys in an electrolyte with fluoride ions. These two titanium alloys, like other materials developed to replace the bone tissue in the human body, have to be highly corrosion resistant, which is one of the most common requirement in terms of the biocompatibility, damage and fracture prevention. The alloys were analysed by means of the electrochemical impedance spectroscopy and potentiodynamic polarization. The analyzed alloys had good corrosion stability, while nanotubular oxide layer improved their corrosion resistance.

Electrocatalytic properties of porous Ni-Co-WC composite electrode toward hydrogen evolution reaction in acid medium

Porous Ni-Co-(WC)x ternary composite electrodes were fabricated by means of electrodeposition on a foam Ni substrate. The surface morphology and microstructure of the electrodes were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrocatalytic properties of porous Ni-Co-(WC)x electrodes for hydrogen evolution reaction (HER) in 0.5 M H2SO4 solution at temperatures from 25 to 50 °C were conducted by means of cathodic polarization, electrochemical impedance spectroscopy (EIS), cyclic voltammetry and chronoamperometry (CA). These Ni-Co-WC electrodes are efficient electrocatalysts for HER. Compared with the porous Ni-Co electrode, the porous Ni-Co-(WC)x electrode exhibited a lower HER overpotential, a lower electrochemical impedance, a lower apparent activation energy and a higher exchange current density. The apparent exchange current density of porous Ni-Co-(WC)x (x = 10, 20, 30 and 40 g/l) is 2.01, 3.01, 7.8 and 19.91 times of porous Ni-Co electrode, respectively. With the increase of WC concentration and temperature, the apparent exchange current density of HER was enhanced. With the increase of WC concentration and potential, the HER resistance and the activation energy decreased. The Ni-Co-(WC)x electrode exhibited superior corrosion resistance and stability for HER.

Application of Absorption by Potassium Taurate Solutions to Post-combustion CO2 Removal from Flue Gases with Different Compositions and Flowrates

Climate change issues have led many countries to actively participate to international conventions, with the aim of reducing the impact of human activities on the environment. In this framework the Paris Agreement has established to keep the temperature rise below 2°C above the pre-industrial level.One suitable mitigation option is to remove carbon dioxide, before it is emitted into the atmosphere. Several technologies are available, including chemical processes where acid gases are absorbed by aqueous alkanolamines solutions. Although this process is already widely used in industry, these solvents are characterized by high energy requirements, in addition to other disadvantages such as corrosion and degradation. Recently, alternative solvents are being studied as possible substitutes for traditional amine solutions. Precipitating solvents are considered in chemical absorption processes because of their characteristic of forming a solid phase, which allows the removal of one reaction product from the liquid solution, therefore shifting the equilibrium of the reaction and so enhancing the mass transfer of the CO2 from the vapor phase to the liquid phase. One class of precipitating solvents are amino acids, with several different types which can be used in aqueous solution. Previous studies have identified the most suitable types for the capture of carbon dioxide and have highlighted the additional advantages of low corrosion and high stability towards degradation, in particular for the amino acid species containing a sulfonic group, such as taurine.This work focuses on the use of potassium taurate aqueous solutions for the removal of carbon dioxide from flue gases from natural gas and coal-fired power plants. The aim is to evaluate changes in the solvent performance arising from changes in the flue gases composition and flowrates.The obtained results confirm the possible application of the potassium taurate aqueous solution for CO2 removal both in coal-fired and in NGCC power plants, with different energy requirements.

Redefining passivity breakdown of super duplex stainless steel by electrochemical operando synchrotron near surface X-ray analyses

Passivity determines corrosion resistance and stability of highly-alloyed stainless steels, and passivity breakdown is commonly believed to occur at a fixed potential due to formation and dissolution of Cr(VI) species. In this work, the study of a 25Cr–7Ni super duplex stainless steel in 1 M NaCl solution revealed that the passivity breakdown is a continuous degradation progress of the passive film over a potential range, associated with enhanced Fe dissolution before rapid Cr dissolution and removal of the oxide. The breakdown involves structural and compositional changes of the passive film and the underlying alloy surface layer, as well as selective metal dissolution depending on the anodic potential. The onset of passivity breakdown occurred at 1000 mV/Ag/AgCl, and Fe dissolved more on the ferrite than the austenite phase. With increasing potential, the passive film became thicker but less dense, while the underlying alloy surface layer became denser indicating Ni and Mo enrichment. Rapid Cr dissolution occurred at ≥1300 mV/Ag/AgCl.