Probability Of Corrosion Research Articles

Combined effects of protective film and oxidant on the performance of the supercritical water oxidation system with a film protective reactor: A simulation study

Supercritical water oxidation (SCWO) is a promising technology for treating organic waste and recovering energy. Water film protective reactor (WFPR), which is also referred to as transpiring wall reactor, provides a solution to corrosion and salt plugging issues. Three novel film protective reactors (FPRs) using air, nitrogen, and hydrogen peroxide as protective fluids were proposed to improve the corrosion and cost issues in WFPRs. Detailed optimized process parameters and flow field characteristics within the FPRs were obtained using Aspen Plus and computational fluid dynamics, respectively. The anti-corrosion performance and prevention of salt plugging in the FPRs were analyzed, and economic analyses for SCWO systems with different FPRs were conducted. Results indicate that the WFPR and hydrogen peroxide FPR present good solubility for inorganic salts but a high probability of corrosion. An SCWO system with the WFPR or nitrogen FPR is more competitive for industrial plants compared with other SCWO systems.

Comprehensive investigation of butyl stearate as a multifunctional smart concrete additive for energy‐efficient buildings

Using of phase change materials (PCM) for increasing energy savings in sustainable buildings is receiving a lot of interest in commercial applications. Butyl stearate (BS), as PCM, can be used to maintain ambient temperature in the human comfort zone and prevent temperature fluctuations by enhancing the thermal properties of concrete. The long-term effects of BS on concrete are not well known. In this study, the applicability of BS, as a smart concrete additive, by direct incorporation in the concrete structure was investigated comprehensively including thermal, rheological, and corrosion behaviour. The thermal characterization of PCM was achieved using DSC, TGA, thermal conductivity, and thermal buffering experiments. Thermal storage capacity of BS was measured to be 134.2 J/g, which is high enough to be used for passive solar energy storage in buildings. The fresh concrete experiments revealed that workability and flowability of fresh concrete mixes were improved. The maximum hydration temperature was reduced, and a retarding effect was observed by the addition of BS. Moreover, the corrosion behaviour of steel embedded in concrete with BS as PCM was studied in a solution of NaCl (3.5 wt%) representing an aggressive environment by utilizing electrochemical impedance spectroscopy (EIS) for long-term corrosion tests that lasted for 1 year. The open circuit potential of steel in concrete with BS showed noble potential indicating low corrosion probability. The FESEM images and polarization resistance (Rp) values showed that the addition of BS in concrete decreases corrosion of the rebar in comparison with concrete without BS. Addition of BS not only enhances thermal capacity but also exhibits corrosion protection of rebar by hindering penetration of chloride ions into the concrete.

Corrosion of orthodontic archwires in artificial saliva in the presence of Lactobacillus reuteri

The aim of this work was to examine the influence of probiotic supplements, recommended for use in orthodontic patients, on the corrosion stability of stainless steel and three types of NiTi orthodontic wires. Electrochemical studies, polarization measurements and electrochemical impedance spectroscopy, were conducted in artificial saliva with oral probiotic supplement as well as in saliva containing the probiotic bacteria L. reuteri alone. Obtained results show that probiotic bacteria L. reuteri and probiotic supplement influence on a general corrosion rate as well as on likelihood of pitting corrosion occurrence, and their effect is dependent on the type of alloy and coating. In general the probiotic supplement has more corrosive influence than bacteria alone as it increases the probability of localized corrosion of studied orthodontic wires. On the other hand probiotic bacteria do not increase the possibility of localized corrosion occurrence in any of studied wires than rather decrease the general corrosion rate of stainless steel wires. Based on the obtained results it is concluded that the additional substances from probiotic supplement are responsible for the localized corrosion of studied wires rather than probiotic bacteria L. reuteri alone.

Investigation of the Role of Nano-Titanium on Corrosion and Thermal Performance of Structural Concrete with Macro-Encapsulated PCM.

The present study aims to investigate the impact of thermal energy storage aggregate (TESA) and nano-titanium (NT) on properties of structural concrete. TESA was made of scoria encapsulated with phase change materials (PCMs). Coarse aggregates were replaced by TESA at 100% by volume of aggregate and NT was added at 5% by weight of cement. Compressive strength, probability of corrosion, thermal performance, and microstructure properties were studied. The results indicated that the presence of TESA reduced the compressive strength of concrete, although the strength was still high enough to be used as structural concrete. The use of TESA significantly improved the thermal performance of concrete, and slightly improved the resistance of corrosion in concrete. The thermal test results showed that TESA concrete reduces the peak temperature by 2 °C compared to the control. The addition of NT changed the microstructure of concrete, which resulted in higher compressive strength. Additionally, the use of NT further enhanced the thermal performance of TESA concrete by reducing the probability of corrosion remarkably. These results confirmed the crucial role of NT in improving the permeability and the thermal conductivity of mixtures containing PCM. In other words, the charging and discharging of TESA was enhanced with the presence of NT in the mixture.

Effect of Vietnamese Fly Ash on Selected Physical Properties, Durability and Probability of Corrosion of Steel in Concrete.

Vietnamese fly ash was used as a partial replacement for ordinary Portland cement in the proportions of 10%, 20% and 40%, while the water to cementitious ratios were kept constant at 0.42, 0.5 and 0.55, respectively, for three groups. The compressive strengths of all mixes were determined up to 90 days. The acid resistance of fly ash concrete was examined by the mass loss and compressive strength loss of 100 × 100 × 100 mm3 cubes immersed in a 10% H2SO4 solution. The probability of steel corrosion in the fly ash concrete was assessed by measuring the half-cell potentials of steel bars within beams dimensions of 100 × 100 × 500 mm3, and the flexural strengths of these beams after 300 days of immersion in a 5% NaCl solution were determined. The results demonstrate that the compressive strength of fly ash concrete is reduced at an early age but increases as the concrete continues to hydrate. The fly ash increases the sulfuric acid resistance of concrete. Fly ash additions have only a limited effect on reducing the risk of probability of corrosion of steel in the concrete. The load capacities of 10% and 20% fly ash reinforced concrete beams are higher than that of the control beams after 300 days immersed in a 5% NaCl solution.

Corrosion behaviour study of heat-resistant steel under oxidation and reduction atmosphere

High-temperature corrosion is one of the main problems that plague the safe operation of thermal power plants. Especially for units burning high-sulfur coal, the probability of high-temperature corrosion is much greater than that of units burning low-sulfur coal. In this paper, the 12Cr1MoV steel used in power plants is selected as the research object, the experiment studied the corrosion behavior of H2S, SO2 and air in the temperature range of 400-500°C. We found that 12Cr1MoV has the highest corrosion rate in the H2S atmosphere, the second in the air, and the slowest in the SO2 atmosphere.

Condition assessment of selected reinforced concrete structural elements of the bus station in Kielce

The paper presents the results of the research aimed at assessing the condition of reinforcement and concrete cover in selected elements of the structure of the most recognizable structure in Kielce, i.e. PKS station, located at Czarnowska Street. Currently, demolition works are underway resulting from the planned modernization. The assessment of the corrosion risk of the reinforcement in the construction elements was carried out with the use of a semi-non-destructive electrochemical method. The use of this method made it possible to determine the probability of reinforcement corrosion in the selected areas and to estimate its rate. The protective properties of concrete cover were checked by the carbonation test (test using a 1% phenolphthalein solution) and phase composition analysis (X-ray diffraction analysis). In order to determine the position of the reinforcing bars and to estimate the concrete cover thickness distribution in the areas corresponding to the aforementioned measurements, ferromagnetic detection system was used.

Non-coated and Coated Reinforcement in Concrete Corrosion Probability Measurement in Accelerated Environment by Wenner Method

Non-coated and Coated Reinforcement in Concrete Corrosion Probability Measurement in Accelerated Environment by Wenner Method

Prevention of Reinforcement Corrosion in Concrete by Sodium Lauryl Sulphate: Electrochemical and Gravimetric Investigations

Prolonged corrosion inhibition response of sodium lauryl sulphate (SLS) on steel reinforcement in contaminated concrete was investigated by gravimetric method and electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy. Using half cell potential measurements probability of steel reinforcement corrosion was monitored for a period of 480 days. FT-IR spectroscopic analysis of the corroded products deposited on the steel reinforcement revealed the mechanism of corrosion inhibition. Modification in the surface morphology of steel specimens in the concrete was examined by optical microscopy. During the period of investigation (480 days), SLS showed appreciable corrosion inhibition efficiency on the steel reinforcement in concrete.

Evaluation of the Corrosion of AISI 304 Stainless Steel Embedded in Sustainable Concrete with High Volumes of Scba-SF Exposed in Marine Environment

The present study evaluates corrosion by electrochemical techniques of AISI 304 Stainless Steel and AISI 1018 Steel, embedded in sustainable concrete mixtures made with high volumes of SCBA-SF as a partial substitute for Portland Cement, the substitutions were 0%, 30%, 40% and 50%. The design of the concrete mixtures was made according to ACI 211.1, for a ratio w/ c = 0.65. The specimens to be evaluated were exposed in a marine or aggressive environment (Seawater) and water (Medium Control). The electrochemical techniques used were that of Corrosion Potential, Ecorr (ASTM C-876-15) and Corrosion Kinetics, Icorr (ASTM-G59). According to the results obtained after more than 150 days of monitoring, AISI 1018 Steel presents Ecorr values that indicate a 90% probability of corrosion and Severe Corrosion, depending on the percentage of substitution of SCBA-SF used. The AISI 304 Stainless Steel presented a significantly higher corrosion resistance than AISI 1018 Steel, reporting values of Ecorr that indicate a 10% probability of corrosion and magnitudes of Icorr indicating a negligible to moderate corrosion level, with a better performance in the mixes with 30% and 50% the substitutions of SCBA-SF.

INFLUENCE OF GREEN CORROSION INHIBITOR ON REINFORCED CONCRETE ATTACKED BY MAGNESIUM SULPHATE

Sulphate attack is one of the phenomena that may cause gradual but severe damages to concrete structures durability. Sulphate attack is due to a series of chemical reactions between sulphate ions and principle components of the cement paste microstructure. In this work the effects of 1.5% and 4.5% MgSO4 additions on concrete durability of 0.45 and 0.65 water/cement ratios (w/c) and the residual effects on corrosion of steel reinforcement were investigated using concrete resistivity. The results shows that 2% addition of Bambusa arundinacea green inhibitor improved the concrete resistivity of MgSO4 contamination concrete by 54% and 64% for 0.45 and 0.65w/c ratios respectively. Thus comparatively, Bambusa arundinacea inhibitor performed far better than Calcium nitrite, Ethanolamine inhibitors and even the non-contaminated control sample. This confirmed a linear relationship between concrete resistivity and probability of corrosion in concrete. Concrete resistivity has proven to be effective parameter for the estimation of the risk of steel reinforcement in concrete.

Comparative Half Cell Potential and Concrete Resistivity Corrosion Probability Assessment of Embedded Coated Steel Reinforcement in Concrete Accelerated Environment

Comparative Half Cell Potential and Concrete Resistivity Corrosion Probability Assessment of Embedded Coated Steel Reinforcement in Concrete Accelerated Environment

Comparative Corrosion Probability Variance of Non-Inhibited and Inhibited Reinforcement in Concrete and Exposed to Accelerated Medium Using Wenner Method

Comparative Corrosion Probability Variance of Non-Inhibited and Inhibited Reinforcement in Concrete and Exposed to Accelerated Medium Using Wenner Method

Effect of chemical admixtures on concrete’s electrical resistivity

PurposeThe purpose of this paper is to verify the influence of superplasticizer and air entrainment admixtures (AEs) in the electrical resistivity of concrete.Design/methodology/approachTen different types of concrete have been studied. Three levels of superplasticizer and air AEs have been used (0.20, 0.35 and 0.50 per cent). Concrete samples were cast and the electrical resistivity was monitored at the ages of 28, 63 and 91 days. Compressive strength and density tests have also been executed.FindingsThe superplasticizer admixture presented an optimal level of 0.35 per cent that significantly increased the electrical resistivity. The air AEs at the same dosage caused a considerable decrease in the electrical resistivity. The concrete with air AEs showed highest resistivity/MPa ratio.Research limitations/implicationsThe results should be carefully extrapolated for other materials and admixtures.Practical implicationsThe usage of chemicals admixture in concrete is extremely common nowadays. However, only a few authors have studied the impact of such materials on the concrete’s electrical resistivity. Since many other researchers have already correlated electrical resistivity with other concrete’s properties, such as strength, setting time and corrosion probability, it is important to better understand how superplasticizers and air-entraining agents, for instance, impact the resistivity.Originality/valueThe vast majority of studies only tested the resistivity of cement paste or mortar and usually for short period of time (up to 28 days), which seems not to be adequate since the cement reaction continues after that period. This paper fills this gap and studied the impact of admixture on concrete and for a period of 91 days.

Resistance of Chlorides-Induced Corrosion of Steel Bar Embedded in CNTs-OH Modified Concrete

Aim of this paper is to evaluate the influence of hydroxyl carbon nanotubes (CNTs-OH) content (by 0.1-0.5% of cement weight) on the resistance of chlorides-induced corrosion of steel bar embedded in concrete. The corrosion process of concrete was monitored by using half-cell potential method (Ecorr, mv CSE). Test results show that the addition of CNTs-OH considerably increased the resistance of rebar chlorides induced corrosion of concrete, and the optimum content of CNTs was about 0.3% by mass of cement. Simultaneously, results also indicate that the measuring position impacted the corrosion potential value, in which the point on the water/air interface had the highest corrosion probability. In addition, the water absorption and SEM of concrete containing CNTs-OH were also investigated, and the pore-filling effect of CNTs-OH was observed to improve the properties of concrete.

Synthesis ofl-Histidine-Attached Graphene Nanomaterials and Their Application for Steel Protection

Graphene-based carbonaceous materials have aroused great attention among the material protection fields due to their excellent impermeability. However, graphene nanosheets tend to aggregate in a polymer matrix and trigger microgalvanic corrosion, which potentially aggravates metal deterioration. Herein, we present a facile strategy to improve the protective property of graphene by tailoring graphene oxide with l-histidine molecules. The resultant functionalized graphene nanomaterials, without direct connections, can be well-dispersed in a polymer matrix. Electrochemical impedance measurements demonstrated that embedding a small percentage of well-dispersed functionalized graphene in epoxy coatings significantly enhanced the impermeable properties of the as-prepared composite coatings. The probability of galvanic corrosion of graphene with metal was largely inhibited and verified through the scanning vibrating electrode technique. The protection mechanism of composite coatings is interpreted as the barrier...

Structural Repair to Conserve Langkawi’s Main Tourist Attraction: Practical Approach

Direct exposure to marine environment causes accelerated corrosion process of all reinforced concrete structures, consequently, causes cracks, deterioration and overall reduction in the sstructural integrity. The aim of this paper is to study the deterioration and technique of repair work at Eagle Square as a landmark of Langkawi Island. Most of the structural problems which occurred at the splash zone were spalling and delamination on beam, slab and pile cap. Material testing was carried out at selected locations to ob tain detailed information relating to the extent and causes of deterioration of the structure. The result showed that the carbonation depth was smaller than concrete cover and the amount of chloride ions was 0.23% by mass of cement and 50% of the splash zone was having 90% probability of corrosion. After obtaining the necessary data, the study directed towards deciding the remedial work. The Eagle Square structure members were successfully repaired in eight (8) months with proper works planning and repair technique appropriate to the damages.

Water permeability of argillite-based ceramic tiles

The article presents the results of experiments to determine the interconnection between water impermeability and water absorption of ceramic tiles obtained on the basis of argillite-like clays that are widespread in the Southern Russia. It is shown that with a decrease in water absorption, the permeability of ceramics is normally reduced. It is found out that with 5% water absorption, a tile can be considered guaranteed waterproof. In this case, the index is independent of the tile thickness. It has been proved that it is possible to reduce the water absorption and increase the bending strength of tiles based on argillite-like clays by finer grinding of raw material or increasing the burning temperature. It is justified that the production of ceramics with high strength and low water absorption makes it possible to produce tiles with a smaller thickness and weight, as well as with lesser probability of biological corrosion.

Behavior of galvanized reinforcements in carbonated and non- carbonated media

The present work aimed to study the electrochemical behaviour of galvanized reinforcements in carbonated and non-carbonated media of different alkalinities. For this purpose, galvanized steel bars with 6.3mm of diameter, cut into 100 mm segments, were used. The reinforcements were immersed in saturated solutions of calcium hydroxide and potassium hydroxide, simulating the liquid phase of the concrete pores. The electrochemical behaviour of the reinforcement was evaluated in environments with potentials of hydrogen (pHs) ranging from 12.6 to 13.5. These reinforcements were monitored by means of electrochemical measurements using the linear polarization resistance technique. The results showed that galvanized bars only passivate at pHs lower than 13.2. It has also been observed that, in carbonated environment, with a pH of about 8.5, there is a low probability of corrosion of the galvanized reinforcements, what does not take place for carbon-steel reinforcements. This demonstrated that galvanized reinforcements can be used in environments subjected to carbonation, but this should be done with caution when there is a possibility of high levels of alkalinity, depending on the used materials

Corrosion of Nickel-Titanium Orthodontic Archwires in Saliva and Oral Probiotic Supplements.

ObjectivesThe aim of the study was to examine how probiotic supplements affect the corrosion stability of orthodontic archwires made of nickel-titanium alloy (NiTi).Materials and MethodsNiTi archwires (0.508x0.508 and having the length of 2.5 cm) were tested. The archwires (composition Ni=50.4%, Ti=49.6%) were uncoated, nitrified and rhodium coated. Surface microgeometry was observed by using scanning electron microscope and surface roughness was measured by profilometer through these variables: roughness average, maximum height and maximum roughness depth. Corrosion was examined by electrochemical method of cyclic polarisation.ResultsRhodium coated alloy in saliva has significantly higher general corrosion in saliva than nitrified alloy and uncoated alloy, with large effect size (p=0.027; η2=0.700). In the presence of probiotics, the result was even more pronounced (p<0.001; η2=0.936). Probiotic supplement increases general and localised corrosion of rhodium coated archwire and slightly decreases general corrosion and increases localised corrosion in uncoated archwire, while in the case of nitrified archwire the probability of corrosion is very low. The differences in surface roughness between NiTi wires before corrosion are not significant. Exposure to saliva decreases roughness average in rhodium coated wire (p=0.015; η2=0.501). Media do not significantly influence surface microgeometry in nitrified and uncoated wires.ConclusionProbiotic supplement affects corrosion depending on the type of coating of the NiTi archwire. It increases general corrosion of rhodium coated wire and causes localised corrosion of uncoated and rhodium coated archwire. Probiotic supplement does not have greater influence on surface roughness compared to that of saliva.