Corrosion Rate Measurements Research Articles

Mechanical Performance and Corrosion Behaviour of Aluminum7075 Reinforced by Nano-Titanium dioxide

في هذه الدراسة ، تم تطبيق تقنية الصب بالتحريك (SCT) لتكوين مركب الألمنيوم (Al) النانوي مع نسب وزنية مختلفة من مسحوق ثاني أكسيد التيتانيوم النانوي (TiO2). تم فحص الخصائص البنائية ,الميكانيكية والتآكل لمتراكبات النانو. دراسة البنية المجهرية تمت عن طريق المجهر الإلكتروني الماسح (SEM) ، بينما تم الحصول على التركيب البلوري للعينات باستخدام حيود الأشعة السينية (XRD). بالإضافة إلى ذلك ، تم غمر المركبات النانوية في محلول 0.5 مولاري من حمض الهيدروكلوريك لقياسات معدل التآكل والديناميكية الفعالة. أظهرت النتائج أن أفضل عينة كانت 0.03٪ ، حيث زادت الصلابة بنسبة 23٪ ، لكن قوة الشد زادت إلى 52٪. حيث أظهرت صور SEM للعينات المعززة بالجسيمات النانوية تجانسًا وانتشارًا واضحًا للجسيمات النانوية في المصفوفة. لذلك ، فإن إضافة جزيئات TiO2 النانوية إلى معدن الألمنيوم أدى إلى تحسين صلابة وقوة الشد للمركبات النانوية بشكل ملحوظ. بالمقابل أظهرت نتائج التآكل أن المواد المركبة النانوية لديها مقاومة تآكل أعلى من المواد المركبة القائمة على Al7075.

Development of an integrated online deposition and corrosion monitoring system in a full-scale solid waste CFB boiler

Solid waste incineration is a clean and sustainable approach for solid waste management. However, ash deposition and corrosion remain a critical issue due to fuel’s inherent enrichment of alkali chlorine. This study develops an integrated online deposition and corrosion monitoring system to enhance the operational safety and efficiency of solid waste incineration boilers. This system combines linear polarization resistance (LPR) for corrosion rate estimation with heat flux measurements for ash deposition analysis. It can offer a novel approach for real-time monitoring of heat exchangers’ safety during solid waste combustion. It was deployed in a full-scale circulating fluidized bed (CFB) boiler that purely combust solid wastes. Key findings demonstrate the system’s capability to deliver continuous, real-time data, crucial for the dynamic control of combustion processes and the maintenance of heat transfer surfaces. Its robust diagnostic capabilities were evident across various scenarios. Specially, initial corrosion rates sharply increase with deposition rates due to the enrichment of alkali chlorine on inner deposit layer, in which chlorine serves as a catalyst, facilitating the rapid penetration and aggravation of corrosion by other agents. As deposit further buildup, the corrosion rate steadily decreases along with surface temperature, highlighting a dynamic interaction. Moreover, measured corrosion rates can quickly response to temperature variations. Such multi-process online monitoring system provide more possibilities to investigate the inherent interaction between deposition and corrosion. Therefore, this work offers insights that could significantly influence operational strategies, maintenance protocols, and the overall reliability of waste-to-energy technologies.

Evaluation of the Condition of the Bottom of the Tanks for Petroleum Products-Forecast of the Remaining Operating Life

Corrosion rate measurements in the tank enable us to develop a new model for predicting the remaining operating period of the tank. The empirical model for the study of bottom plate thicknesses and corrosion pits is more conservative than the standard linear model, as it considers the autocatalytic nature of the corrosion process. We used the double exponential distribution of maximum values (Gumbel's) to evaluate the maximum depth of pits, and the double exponential distribution of minimum values to evaluate the minimum values of the plate thickness. A comparison of the values of the parameters obtained using linear extrapolation and exponential models indicates the unreliability of linear extrapolation, since disregarding dynamic processes underestimates the actual rate of corrosion.

Effects of electrochemical corrosion on retrogressed and different reaged friction stir welded AA7075-AA6082 dissimilar welds

ABSTRACT The research is primarily to study the microstructure, tensile and electrochemical corrosion behaviour of friction stir welded AA7075-T651-AA6082-T6 dissimilar welds, subjected to retrogression and reaging at 280⁰C for 5 min followed by aging at 110⁰Cfor 1 , 5 , 10 and 24 h respectively. The AA7075-AA6082 welds were made using optimum parameters such as feed rate 80 mm/min, tool rotation speed 980 rpm, and tilt angle 2 o . The alloys of 100 × 50 × 6mm³ plates were welded with a conical tapered tool pin profile. Further, the welds were scanned for potentiodynamic polarisation with a 3.5 percentNaCl solution. Optical metallographic (OM) images were revealed to determine morphology andcorrelate with the measured corrosion rate. Here, the dissimilar friction stir weld AA7075-AA6082-aged for 5 h had an ‘Ultimate tensile strength’ (UTS) of 269.73N/mm2 due to coherent precipitates. Moreover, at 24 h, the lower tensile strength of 226.06 N/mm2 was observed, due to coarser precipitates across the AA7075-AA6082 weld cross-section. Due to over-aged coarse precipitates, the corrosion rate of 6082BM and weld metal had increased to 5.110e + 003mpy and 1.010e + 003mpy. Under other aged conditions, the corrosion rate was decreased below 0.001mpy.

Carbonation and corrosion of steel in fly ash concrete, concluding investigation of five-year-old laboratory specimens and preliminary field data

Carbonation development and reinforcement corrosion were investigated on concretes exposed for a five-year period at 90% RH, 20 ℃, and 5% CO2, and for a six-year period at natural carbonation. Portland cement-based binders with 0%, 18%, and 30% fly ash were investigated. The fly ash blends showed lower carbonation resistance compared to PC both at laboratory and field exposure, a large difference in carbonation performance was observed between the laboratory exposed specimens. The carbonation rate was fastest on the laboratory specimens and showed square-root time dependency the first 2.5 years, but reduced rate at later age. Deeper carbonation depths were in general observed in the vicinity of the reinforcement compared to the unreinforced laboratory exposed specimens. Not all specimens were fully carbonated at the steel-concrete interface. The correlation between degree of carbonation of the steel-mortar interface, the open circuit potential, and the observed corrosion of the steel bars varied between binders and bar position (top or bottom). The measured corrosion rate in the laboratory exposed (90% RH, 20 ℃, and 5% CO2) carbonated concrete was on average 0.2 μA/cm2, with an upper value of 0.6 μA/cm2. The highest corrosion rate was measured in the fly ash concrete. No corrosion rate data are yet available for the field exposed concretes.

Tribo-Corrosion Control with Molecules of Bio-Origin: Experimental Studies and Theoretical Insights

Tribo corrosion control of 6061 aluminum alloy was done by using naturally available Boswellia serrata (BWS) extract as green inhibitor. Studies were done in artificial sea water slurry containing 0.03% sand particles via a submerged jet impingement technique. Electrochemical studies were the majour techniques adopted for corrosion rate measurement in the absence and in the presence of inhibitor. Investigation was done at different flow rates and at different temperatures. Detailed surface study was done for sand particles before and after impingement using scanning electron microscope. Surface morphology of aluminum sample was done before and after the addition of inhibitor. For a given flowrate inhibition efficiency decreased with increase in temperature. This suggested the possibility of physical adsorption. Results were fitted into suitable adsorption isotherm. Mechanism of adsorption was supported and substantiated by quantum chemical calculations using Density Functional Theory (DFT). The best corrosion–erosion resistance was obtained at a concentration of 1000 ppm Boswellia serrata at 303 K under 4 L min−1. DFT studies supported the adsorption mechanism of the inhibitor on the surface of metal under tribological conditions. The outcome of this work will help in research that is focused on development on green inhibitors for corrosion inhibition under dynamic multi flow conditions.

Microstructure and corrosion behavior of a hot-rolled pure Mg after annealing at various temperatures

The microstructure and corrosion behavior of a hot-rolled pure Mg in the rolled state and after annealing at various temperatures was studied in this paper. It was found that the hot-rolled pure Mg after annealing at 250 °C, 350 °C, 400 °C, 500 °C and 550 °C showed homogeneous microstructures and the presence of a partially recrystallised tissue in hot rolled pure Mg. Corrosion of annealed Mg mainly occurred at grain boundaries, which stemmed from the relatively higher energy and chemical activation on the grain boundaries. Initial corrosion sites were provided by different proportions of High angle grain boundaries (HAGBs). The corrosion rate tends to increase and then decrease with increasing grain size. The Mg annealed at 450 °C showed a non-uniformed microstructure, with a lower fraction of the recrystallization grains and higher fraction of HAGBs, leaving to the severe localized corrosion and the highest corrosion rates. Corrosion rate measurement indicated that there existed a curvilinear relationship between the corrosion rate and grain size.

Development of plant integrity inspection on the API 5L X65 material under humid conditions: emerging fitness for service assessment approach

This work reports the development and corresponding monitoring of pipeline integrity inspection in the arid zone, which typically experiences external corrosion. The recent method poses the challenge which indaquate to synchronize the internal and external corrosion monitoring of API 5L X65 material trunklines and flowlines owing to imperfect types of inspection on the external progressive damage only. Red-clay soil, soil porosity, oxygen content, and moisture become critical parameters for controlling the corrosion of the above conditions. The combination of ultrasonic guided wave test, visual inspection, and design life calculation is implemented to address the above challenges. Based on the results, trunkline B (12-inch) is more severe than A (18-inch), with the shorter measured remaining thickness and remaining life of 4.35 mm and 1.9 years. External corrosion and visual inspection results show that sand threatens corrosion. The external corrosion product is evident at the 3 and 6 o’clock positions, corresponding to the exposure of the buried pipelines to moisture. The maximum metal loss in the trunk is 14.5 %, which confirms the environment of trunkline B. The internal corrosion has little effect on the integrity of the plant. Despite the three fluid phases inside the flowlines and trunklines, the measured corrosion rate on the coupon is relatively lower. The highest recorded corrosion rate is 0.443 mmpy, while the contribution to internal corrosion from the rest of the monitor well is insufficient. This research is designed to model the strategy to utilize instrumentation of Ultrasonic tests and human intervention in corrosion mitigation

Investigation of Microstructure, Mechanics, and Corrosion Properties of Ti6Al4V Alloy in Different Solutions

There is a scarcity of research on the characterization of the behaviour of titanium and its alloys in highly corrosive environments. These materials are highly recommended for use in various industries such as aviation, maritime, medical, and chemical, due to their perceived superior corrosion resistance. This research examines the mechanical and corrosion characteristics of Ti6Al4V material when exposed to solutions containing 9% NaCl, 25% HCl, and a mixture of 9% NaCl and 25% HCl. Prior to the corrosion process, the prefabricated Ti6Al4V samples underwent microstructure analysis, hardness assessment, and wear evaluation. The microstructure characterization revealed that the microstructure of the Ti6Al4V alloy is composed of α and modified β phases. The Ti6Al4V sample’s hardness value was determined to be 334.23 HB. The Ti6Al4V sample’s wear rate was determined to be 0.0033 g/Nm, while the friction coefficient was determined to be 0.0326. Corrosion testing was conducted at intervals of 24, 48, 72, 168, and 336 h. Based on the corrosion rate measurements, the sample exhibited the minimum corrosion rate of 1.928519 mg/(dm2·day) in a 9% NaCl environment. The sample with a combination of 9% NaCl and 25% HCl had the maximum corrosion rate, measured at 6.493048 mg per square decimetre per day. The formation of a larger oxide layer in the Ti6Al4V corrosion sample immersed in a 9% NaCl solution serves as a protective barrier on the surface and enhances its resistance to corrosion.

Experimental Bench Tests on the Corrosion Resistance and the Environmental Safety of Structural Materials of the Cooling System of Nuclear Power Plant

Biological pollution creates significant obstacles in the operation of power plants' technical water supply cooling systems (SCS). To minimize biological pollution, methods of corrective treatment with biocides are implemented. While these biocides effectively prevent fouling of the cooling system, they can also adversely affect the environment and structural materials. By evaluating structural materials' corrosion resistance and biocides' environmental safety for the cooling water during biocide treatment, any potential issues can be identified and addressed before they become a safety or operational concern. The paper presents the results of bench tests of the corrosion resistance of structural materials SCS, corrosion aggressiveness of the biocides: sodium hypochlorite NaClO and 2, 2-dibromo-3-nitriloropionamide (DBNPA), and the results of measurements of the concentration of biocides and their decomposition products to assess compliance with environmental standards when discharging return water when applying from biocides treatment. The cooling water SCS of the Rivne NPP (Nuclear Power Plant) was chosen as the research object. Bench corrosion tests were carried out using samples of corrosion indicators from materials: steels Ст20, 08Х18Н10Т; copper alloy МНЖ-5-1 and aluminum, which are defined as analogs of structural materials of the technical water supply system of the Rivne NPP. The conditions of operation of the technical water SCS of the Rivne NPP were simulated on the test bench, and corrosion rate measurement was carried out by the gravimetric method.

Superhydrophobic and anticorrosion Ni-B/WC@MoS2 composite coatings deposited via jet electrodeposition assisted with ultrasonics

BackgroundElectrodeposited surface coatings are used as an important protective measure for metal surfaces such as bearings. Enhancing the corrosion resistance of the coating is the key to practical application. MethodsNi-B/WC@MoS2 composite coatings deposited on 45-steels were prepared by ultrasound-assisted jet electrodeposition combined with hydrothermal modification of nanoparticles. The impact of ultrasonic power on the composite coatings’ physical phase structure, micro-morphology, surface roughness, surface hydrophobicity and corrosion mechanism were evaluated. Significant FindingsUltrasound-assisted power helped to enhance the deposition of WC@MoS2 powder for the composite coatings. The coating surface prepared with the assistance of 270 W ultrasound showed a dense "cauliflower" shape with a superhydrophobic surface contact angle of 153.7° The composite coating assisted by 270 W ultrasonic power was found to have the largest corrosion potential (-218 mV) and the smallest corrosion current (6.8E-07 A/cm2) after the electrochemical corrosion test. The polarization resistance of the coating was 35,568 Ω·cm2, and the measured corrosion rate was 8.0E-3 mm/a. It was three orders of magnitude lower than that of the composite coating without ultrasonic power assistance. The Ni-B/WC@MoS2 coatings obtained with jet electrodeposition assisted by 270 W ultrasonic wave showed good corrosion resistance.

Nondestructive detection and quantification of localized corrosion rates by electrochemical tomography

Localized corrosion is one of the most common causes of early degradation of engineering structures. To non-destructively determine the location, size and rate of localized corrosion in porous media, a new technique, electrochemical tomography (ECT), has been theoretically and numerically formulated. The current work shows the application of ECT to measure corrosion rates in a controlled laboratory setup, with a stable electrolyte and well-defined macro-cell. The results show that ECT is able to replicate the corrosion size and location and can give a good estimation of the corrosion rate. Moreover, the validation of ECT on a well defined localized corrosion system, brings the technique closer to future field applications.

Pollution and Heritage Metals-Effectiveness of Oddy Testing and Mitigation.

Metals are particularly sensitive to some pollutant gases. Many museum showcases and store rooms present atmospheres that can corrode cultural heritage artefacts containing metals. Whilst numerous strategies have been reported to mitigate such situations, avoiding them is preferable. Several approaches to testing materials used in construction, fitting out or dressing are used. The relative merits and drawbacks are discussed. Several parameters of the most widely used, accelerated corrosion 'Oddy' test are investigated. The influence of abrasive on subsequent corrosion of lead and copper coupons are assessed. Quantification methods for tested coupons are reviewed. The influence of test duration and temperature are assessed through comparison with real-life, long-term experience of material behaviour. Direct contact tests with touching the test material are investigated. Several materials present in artefacts are known to potentially cause corrosion when enclosed with metals in other artefacts. A number of situations are investigated with pollution and RH and some corrosion rate measurements. Ways to isolate artefacts or mitigate are explored and a decision support model is further developed.

Effect of Rinsing on Atmospheric Corrosion Environment of KT-1 Aircraft

Corrosion is difficult to predict and manage. Thus, understanding the characteristics of the atmospheric corrosion environment inside and outside the aircraft is necessary. A series of corrosion defects were found inside the KT-1 aircraft; hence, an atmospheric corrosion monitoring set was mounted inside the aircraft to measure the effect of external rinsing on the internal corrosion according to location (fuselage and wing). The effect of external rinsing was analyzed through surface analysis of the specimens and corrosion rate estimation using internal environmental parameters. Steel specimens within the monitoring set exhibited complete corrosion, while Ag specimens showed discoloration. External rinsing reduced the rate of chloride build-up inside the wing. Additionally, time of wetness (TOW) tended to increase with external rinsing regardless of location. Estimated and measured corrosion rates were positively correlated with TOW but negatively correlated with chloride accumulation rate. These results indicate the mixed effect of rinsing and require corrosion control for individual aircraft when deciding whether to apply cleaning for corrosion control.

Impact of surface modification of electrode for aluminium air batteries

Superior electrochemical behaviour of Aluminium makes it the perfect metal for use in aluminium air batteries. It is critical to create effective and affordable anodes for Al-air batteries. This study investigates the effects of nickel and nickel-copper electroplated aluminium anodes on battery operation in both alkaline medium KOH and NaOH. The electrochemical impedance spectroscopy (EIS) and anodic polarization curves are used to study the corrosion behaviour of prepared samples. The surface morphologies were examined by scanning electron microscopy (SEM). The corrosion rate measurements and the constant-voltage discharge measurements were carried out then received data indicated that nickel electroplating increases the efficiency of the aluminium anode more than nickel-copper electroplating. However, it generates a barrier film that shields the aluminium from corrosion without inhibiting battery reactions.

Effect of Oil/Water Intermittent Wetting on CO2 Corrosion in the Presence of Acridine and Myristic Acid

The effect of a paraffinic model oil (LVT-200)-containing select surface-active compounds (myristic acid and acridine) on CO2 corrosion with and without intermittent wetting has been studied. Observations have shown that the presence of myristic acid in the oil phase does not affect the corrosion behavior due to its lack of partitioning in the water phase. However, after direct contact between the oil phase-containing myristic acid and the metal surface, there was a significant decrease in the corrosion rate. This phenomenon gradually diminished at pH 4.0 but was more persistent at pH 6.5. The presence of acridine in the oil phase was shown to have a strong inhibitive effect at pH 4.0, even during the partitioning step. The partitioning of acridine from the oil phase to the water phase at pH 4.0 was confirmed by ultraviolet-visible spectroscopy results. However, there was no inhibitive effect conferred by the presence of acridine on the corrosion rate at pH 6.5. An experimental methodology was developed that facilitated improved simulation of the effect of intermittent oil/water wetting on CO2 corrosion. The electrochemical current response during the oil/water intermittent wetting cycles showed that the persistency of model oil (without surface-active compounds) on the mild steel surface is only a matter of seconds. Corrosion rate measurements showed that the presence of myristic acid renders the oil layer more persistent after intermittent wetting compared to one-time direct contact.

Microstructure and properties of the GEWZ522K casting magnesium alloy based on the Mg–Gd–Nd–Y–Zn–Zr system

The article discusses the solidification and phase composition of the (wt.%) Mg–4.8Gd–2.1Nd–1.6Y–0.4Zn–0.6Zr (GEWZ522K) casting alloy. It is demonstrated that in the as-cast state, the alloy structure comprises primary zirconium particles, dendrites of the magnesium solid solution (αMg), and eutectic intermetallic phases located between dendritic branches. Following solution heat treatment at t = 530±5 °C, the alloy transitions into a single-phase state and can be significantly strengthened through artificial aging after quenching. It is recommended to apply alloy aging at t = 250 °C for 8–10 h or at t = 200 °C for 15–18 h. This approach leads to the maximum strengthening of the alloy, with the best mechanical properties achieved for the alloy aged at t = 250 °C. Regardless of the aging method used, the ultimate tensile strength (UTS) of the samples surpasses 300 MPa, which significantly exceeds that of commercial casting alloys according to GOST 2856-79. The measured corrosion rate for the GEWZ522K alloy is 7.5±0.4 mm/year, that slightly higher than that for the less alloyed commercial alloy ML10 (approximately 2.5 mm/year) tested under similar conditions. Furthermore, the alloy was subjected to tests for ignition resistance when in contact with air. It was observed that with continuous airflow over the specimen’s surface, ignition centers appear at t = 625 °C due to the breakdown of the oxide film, causing the alloy to nearly completely melt. Therefore, the GEWZ522K alloy can be employed as a high-strength casting alloy. However, during the operation of cast parts, particular attention must be paid to safeguarding the surface of these parts against corrosion.

Measurement system for in-situ estimation of instantaneous corrosion rate in supercritical water

Current research of cladding and in-core materials for the supercritical water reactor concept is focused on Fe-Cr-Ni alloys (e.g. 800 H, 310 S). Along the standard measurements of general corrosion rate of materials by exposure testing in autoclaves, where poor reproducibility is an issue, especially when comparing results from different experimental facilities, a good alternative may be the use of in-situ electrochemical measurements. The use of electrochemical methods is, however, more challenging due to complicated instrumentation as well as due to the supercritical water conditions. This paper is focused on the design of an experimental facility for in-situ electrochemical testing at supercritical water conditions, i.e. main circulating loop with autoclave, including the design of the electrode system, electrode leads and their surface insulation coating. Stability of electrochemical measurements has been tested using 2- and 3-electrode set-ups. Finally, surface insulation coating of the electrode leads with the best chemical and mechanical stability during experiment has been chosen for the presented application.

Computational fluid dynamics driven mass transfer model for the prediction of [formula omitted] corrosion in pipelines

A novel, computational fluid dynamics (CFD) driven modelling methodology for predicting CO2 corrosion rates in pipelines is presented. CFD is used to provide accurate predictions of the viscous sublayer thickness and turbulent diffusivities, which are then used within a mass transfer model of aqueous CO2 corrosion. Comparisons with experimental measurements of corrosion rate in horizontal pipe flow and corresponding theoretical predictions, based on empirical correlations and previous CFD approaches, show the new approach is more accurate for flows in the range of pH 4 to 6. However, the key advantage of the new approach is its flexibility. Existing models are inaccurate and highly restrictive, having been derived for very simple cases, such as 1 D pipe flow. In contrast, the new methodology provides a firm, scientific foundation for predicting corrosion rates by determining conditions in the viscous sublayer in much more complex, and practically relevant, flow situations.

Corrosion rates measured under potentiostatic conditions to represent performance of a cermet nuclear waste form

ABSTRACT Electrochemical tests were conducted to assess the corrosion performance of a developmental multiphase cermet nuclear waste form in different conditions. Corrosion currents were monitored as the surface equilibrated in an acidic brine solution during potentiostatic tests at different imposed potentials. Electrochemical impedance spectroscopy was used to quantify differences in the electrical properties of surfaces stabilised at different potentials. The passivating oxides that will stabilise the surface under disposal conditions are formed and maintained during testing. The measured corrosion currents were two orders of magnitude lower for passivated surfaces than for polished surfaces over a wide range of redox conditions. The electrochemical results were correlated with microscopic analyses of the corroded surfaces and physical models of the surface passivation and degradation processes are proposed. The measured corrosion rates are suitable for the long-term performance modeling of cermet nuclear waste forms.