Corrosion control

This study investigates the effectiveness of banana peel extract as a corrosion inhibitor for A36 steel, addressing the need for sustainable solutions in infrastructure maintenance. Controlled corrosion exposure tests were conducted on steel plates treated with banana peel extract at varying concentrations (0%, 5%, 10%, and 15%). Surface characteristics were evaluated through scanning electron microscopy (SEM) and colorimetry. The pH and conductivity were monitored throughout the tests. The corrosion rate was determined using gravimetric characterization. Mechanical testing, including stress-strain behavior analysis, was performed using a universal testing machine. The results demonstrate that banana peel extract significantly enhances the corrosion resistance of A36 steel. Higher inhibitor concentrations, particularly at 15%, resulted in improved mechanical properties, such as ultimate stress, yield stress, modulus of elasticity, resilience, and toughness. SEM analysis revealed the formation of a protective chemisorbed layer, while colorimetry indicated better preservation of the steel's surface characteristics with increasing inhibitor concentration. Banana peel extract is a promising and sustainable alternative for corrosion protection in civil infrastructure. The effectiveness of the inhibitor increases with higher concentrations, providing robust protection against corrosion and enhancing the mechanical integrity of the steel. The utilization of agricultural waste as a functional corrosion inhibitor promotes circular economy principles. By repurposing banana peels, the study contributes to sustainable engineering practices and supports the achievement of the United Nations Sustainable Development Goals. This approach not only mitigates the environmental impact of traditional corrosion protection methods but also offers a viable, eco-friendly solution for extending the lifespan of steel structures.

Bacteriophage particles are the most abundant biological entities on our planet, infecting specific bacterial hosts in every known environment and being major drivers of bacterial adaptive evolution. The study of bacteriophage particles potentially sheds light on the development of new biotechnology products. Bacteriophage therapy, although not new, makes use of strictly lytic phage particles as an alternative in the antimicrobial treatment of resistant bacterial infections and is being rediscovered as a safe method due to the fact that these biological entities devoid of any metabolic machinery do not have affinity to eukaryotic cells. Furthermore, bacteriophage-based vaccination is emerging as one of the most promising preventive strategies. This review paper discusses the biological nature of bacteriophage particles, their mode(s) of action and potential exploitation in modern biotechnology. Topics covered in detail include the potential of bacteriophage particles in human infect...

Magnesium alloys are amidst the most innovative materials for biomedical applications, as they show a set of unique properties, namely appropriate mechanical properties and biodegradability, when compared to other alloys. Although these properties make them suitable for medical implants, the main challenge is the uncontrolled corrosion. Mg degradation is fast, inhomogeneous, localized and often accompanied by hydrogen formation which can lead to complications in vivo. Here, we propose the development of a functional coating, containing natural-based capsules for the controlled release of biocompatible corrosion inhibitors and well known pharmaceutical agents. Empty and loaded capsules toxicity tests were performed as a first step for materials selection. Subsequently, they were incorporated into polyetherimide (PEI) coatings and tested using electrochemical impedance spectroscopy (EIS) under aggressive conditions. The obtained results showed a successful synthesis of natural-based m...

3-((E)-(2-hydroxy-4-methylphenyl)diazenyl] has an inhibiting action. The effects of-1-((E)-(2-hydroxyethylphenylimino)methyl)naphthalen-2-ol (S1H) on the corrosion process of carbon steel in 1 M HCl were studied using two techniques: effective potentiodynamic polarization methods and hydrogen evolution. Furthermore, scanning electron microscopy (SEM) was used to assess surface morphology as corrosion progressed. The results showed that as the concentration of the synthesized chemical is increased, the efficiency of inhibition increases. The studied S1H had a greatest inhibition efficiency of (90.00% using hydrogen evolution method and 91.33% using the hydrodynamic method) at a concentration of 5.0 mM and a temperature of 298 K, the polarization results showed that the examined S1H compound can be used as a mixed type inhibitor. It showed adsorption behavior. For the S1H inhibitor the system obeys Langmuir isotherms. Results of the methods for effective dynamic polarization and hydrogen gas evolution were supported by SEM analyze. Computational chemistry calculations were accomplished using density functional (DFT) method. Theoretical and experimental methods were discussed and the findings displayed that the inhibition efficiency values by closely agreed.

Year upon year the cost of naval corrosion has increased until it is estimated today at 4 % of the Gross National Product. An enlightened approach to materials selection, protection and corrosion control is needed to reduce this burden of wasted materials, wasted energy and wasted money. This paper have been compiled to help marine designers, engineers, and equipment users, understand the causes of naval corrosion and the way in which protective systems and more resistant materials can be used to reduce or entirely eliminate sea water corrosion problems.

The inhibition influence of kiwi juice extract (KJE) for corrosion of steel in 2.5 M hydrochloric acid has been studied by polarization technique at various temperatures and inhibitor concentrations. The maximum inhibition efficiency was 87% at 45 °C and 55 cm3 /L concentration of inhibitor, while the minimum value was 81% at 45 °C and 5 cm3
/L concentration of inhibitor. Polarization curves showed that KJE is a mixed-type inhibitor but the cathode is more polarized than the anode.
The polarization curve curvature region near the potential of corrosion can be investigated depending on the overvoltage data as a function of current densities. These data can be analyzed by suggesting a mathematical model to take into account the influence of diffusion on the charge transfer process. The results obtained from electrochemical technique and mathematical model are in good agreement.

Purpose-This paper aims to study the corrosion inhibition of mild steel in 2.5 M HCl solution by kiwi juice at different temperatures, inhibitor concentration and immersion times. Design/methodology/approach-Box-Wilson experimental design is used for runs distribution and the corrosion rate values are evaluated by weight loss technique. Findings-Corrosion rate increased with temperature according to Arrhenius equation, and the inhibitor adsorbed according to Langmuir adsorption isotherm. Second-order polynomial model is used for data fitting. The optimum conditions were estimated with maximum inhibitor efficiency of 96.1 per cent. Fourier transform infrared analysis showed that the peaks correspond to phenols, and quercitine is the main component. Microstructural, hardness and theoretical quantum studies are also performed. Originality/value-This is one of the first steps in the direction of understanding the corrosion control problems from different views. Kinetics, surface morphology, optimization and mathematical views are taken in to account.

Boiler pipe failures are the most common cause of forced shutdown of power generation units. The oxide layer formed in the inner wall of those pipes is the main cause of overheating failures. From the measured value of the inner oxide layer, it is possible to estimate the remaining life of the component through correlation with parameters already established by the scientific community. Methodologies to estimate remaining life of components in power plants have been developed by Cepel, in accordance of global tendencies and the needs of Brazilian facilities. With the recent equipment acquisition for the detection of defects and measurement of thickness by ultrasonic, it became possible to measure both the pipeline wall and the internal oxide layer thicknesses. This paper presents a comparison between internal oxide layer thickness measurements of pipes performed by ultrasonic (non-destructive technique) and by metallographic preparation associated to optical microscopy (destructive ...

Civil infrastructure assets, including buildings, transportation networks, energy grids and networks, and water-sewer systems, are critical functional components of day-to-day life activity in a modern society. The durability and reliability of these civil infrastructures are largely affected by corrosion-induced structural deterioration. In addition to continual use and increasing traffic demands, natural environmental conditions set degradation due to corrosion damage as a critical condition to durable and reliable infrastructures. Therefore, in order to improve the durability of the bridge infrastructures affected by corrosion in the most efficient manor, we propose a procedure/methodology to manage integrity of corroding RC bridges which is resulted by corrosion assessment by assuming different initial RC systems (including control actions). Our approach involves corrosion characterization in laboratory scale RC samples, quantification of damage based on different corrosion cond...

Chemical surface modification of iron by 1-phosphono-alkane derivatives in aqueous solution has been studied by EIS. The phosphonate layer formation in time was followed by the change of polarization resistance and interfacial capacitance values of iron substrate. Significant corrosion protection was observed due to the spontaneous adsorption layer formation. The protective layer is supposed to have a continuous and dense structure. The inhibition mechanism is anodic type, hindering the active iron dissolution to a large extent. The kinetics of phosphonate layer formation is a complex process. Beside the fast adsorption of molecules on bare iron surface, ordering in the layer structure is taking place during long immersion time. The layer formation process of alkanediphosphonates and monophosphonates were compared.

The effect of some phosphonic acid derivatives on the corrosion behaviour of carbon steel has been investigated in hydrochloric acid solutions by gravimetric and electrochemical methods. Some phosphonic acids were found to have inhibitive effects. These effects depend on the molecular structure: on the number of nitrogen atoms and of phosphono groups, but mainly on their position in the molecules, as shown by the differences in corrosion rate in the presence of various phosphonic acids. The variation of polarisation resistance with time suggests that the inhibitive action of diethylenetriaminepentamethylenephosphonic acid depends mainly on the protective inhibitor film formed on the surface of the steel and is independent of changes in solution composition with time.

Studies were carried out to evaluate the structural effects of four inhibitors (Mono ethanolamine (MEA), phenyl glycidyl ether (PGE), N-(2-hydroxy-3-phenoxy propyl) ethanolamine (NHPE) and N, N'-(-2 hydroxy-3-phenoxy propyl) ethanolamine (N N' HPE) in inhibiting the corrosion of mild steel in 0.1M HCl. Appropriate analytical procedures and instrumentation such as the use of Fourier transform infrared (FTIR) spectrophotometer were employed in the analysis of the structures of the inhibitors. Quantum chemical modeling calculation was employed to better understand the variation in the inhibition efficiencies of the studied inhibitors. After eight weeks of immersing the mild steel sheets in 0.1M HCl with each of the four studied inhibitors, the mean percentage weight loss of the mild steel were 17.74, 30.13, 5.39 and 1.08% for MEA, PGE, NHPE and NN 1 HPE respectively. The FTIR analysis of the structure of the inhibitors shows that the presence of functional groups such as-OH,-NH, ArC = C-and-OCH3 significantly helped to increase the inhibition efficiencies of NHPE and NN' HPE respectively. From the weight loss experiment, it was observed that the inhibition efficiencies of the four studied inhibitors on the mild steel in the acidic media decreased in the following order: N N 1 HPE > NHPE > MEA > PGE which was further confirmed by the FTIR analysis. The lower values of parameters such as ELUMO, energy gap, ionization potential, global hardness and total energy and as well as the higher valves of parameters such as EHOMO, dipole moment, electro affinity, electro negativity, chemical softness, total surface area and polarizability, obtained for NHPE and NN 1 HPE respectively greatly increased the adsorption and donation of their electrons to the metal substrate surface thus were able to more efficiently inhibit the rapid corrosion of the mild steel in the acidic media than the two other studied inhibitors (MEA and PGE).

Corrosion is the deterioration or destruction of metals and alloys in the presence of an environment by chemical or electrochemical means. The phenomenon of corrosion behavior studies is three elements include economic, safety and maintenance. Pitting corrosion is a localized form of corrosion by which cavities or "holes" are produced interring the material layer surface. It's considered to be more dangerous than uniform corrosion damage because it is more difficult to detect, predict and design against. Pitting corrosion can produce pits with open holes or covered with a semi-permeable capsule of corrosion products. In this review, we study about the pitting corrosion mechanism and stages in the manufacture food equipment metals in different conditions and environment.

Hydrogen re-embrittlement on anodically coated high strength steels could be of great concern because the uptake of hydrogen from the corrosion process can cause component failure. A scratched Cd-coated AISI 4340 steel membrane has been coupled with different materials reproducing crevice conditions, and the hydrogen uptake has been measured using a modified Devanathan-Stachurski permeation apparatus. Experimental tests proved that, in presence of a crevice, metals nobler than cadmium strongly enhance local hydrogen reduction on exposed steel areas, thus possibly favoring brittle failure of high strength steel components during service. Therefore, the coupling of uncoated nuts made of noble passive alloys (like Inconel) to Cd-plated AISI 4340 steel bolts should be avoided.

Hydrogen-Induced Cracking (HIC) is one of several related mechanisms whereby absorbed hydrogen atoms can compromise the integrity of components manufactured of low strength steels. A "low strength steel" is defined as having a maximum hardness of 22 HRC (249 HV). The corresponding maximum tensile strength is of the order of 800 MPa (116 ksi). Steels having localized areas with microhardness in excess of 22 HRC are particularly vulnerable to the development of HIC damage. HIC is a term applied to phenomena which occurs at low temperatures (typically less than about 90°C), and must not be confused with high temperature hydrogen attack of low strength carbon-manganese and low alloy steels exposed to hot hydrogen gas-containing environments. This review will highlight main factors that affect HIC development or failure by considering the following: (i) Metallurgical factors (effect of materials and microstructures), and (ii) Environmental exposure factors.

The corrosion behavior of three new generation micro alloyed steels in CO2 saturated brine at different pHs and temperatures was investigated using electrochemical (LPR, Tafel polarization and EIS) and surface analysis (SEM/EDS and XRD) techniques. The micro alloyed steels with ferrite-pearlite microstructures demonstrated better corrosion resistance than the specimen with bainitic structures. The analyses of the corroded surface revealed relative elemental changes of corrosion products revealing that the average ratio of Fe/O increased with increase in pH but decreased with increase in temperature. The electrochemical results indicated that the corrosion resistance of Steel C < Steel B < Steel A. The corrosion kinetics of the steels follow the empirical relation y Ax thus obeying the well-known Log-Log equation (Log Y = Log A + Blog X) which can be used to predict long time corrosion performance. The value of B represents the corrosion kinetics and it decreased with increase in pH depicting corrosion deceleration but increased with temperature signifying corrosion acceleration

Concerns on corrosion and effective coating protection of double hull tankers and bulk carriers in service have been raised especially in water ballast tanks (WBTs). Test protocols/methodologies specifically that which is incorporated in the International Maritime Organisation (IMO), Performance Standard for Protective Coatings for Dedicated Sea Water ballast tanks (PSPC) are being used to assess and evaluate the performance of the coatings for type approval prior to their application in WBTs. However, some of the type approved coatings may be applied as very thick films to less than ideally prepared steel substrates in the WBT. As such films experience hygrothermal cycling from operating and environmental conditions, they become embrittled which may ultimately result in cracking. This embrittlement of the coatings is identified as an undesirable feature in the PSPC but is not mentioned in the test protocols within it. There is therefore renewed industrial research aimed at understanding this issue in order to eliminate cracking and achieve the intended coating lifespan of 15 years in good condition. This paper will critically review test protocols currently used for assessing and evaluating coating performance, particularly the IMO PSPC.

The naphthenic corrosion occurred at room temperature. Insoluble iron naphthenate in mineral oil was formed on the steel surface. The use of in situ optical micrographs during the electrochemical experiments. The use of in situ FTIR to characterize corrosion product. The use of in situ AFM to study corrosion.

Six novel triazole derivatives were synthesized from some substituted benzoic acid with thiocarbohydrazide by grinding method. The synthesized compounds were characterized by infra-red, 1 H, and 13 C-NMR spectra investigations. Synthesized triazole derivatives were tested and evaluated as corrosion inhibitors for low-carbon steel in 0.5 M HCl using weight loss technique. It was found that these compounds had a promising inhibitory action against corrosion of mild steel in acidic solution. Inhibitor with highest performance was evaluated at different temperature and inhibitor concentrations. The inhibition efficiency exceeded 96%. The excellent inhibitor performance was attributed to the formation of inhibitor adsorption films on the steel surface. The adsorption of inhibitor on steel surface followed the Langmuir adsorption isotherm. The experimental results were confirmed via theoretical quantum chemical calculations.

Two new divalent metal(II) aminodiphosphonates with layered structure, namely, Cu(H 3 L 1) 2 .2H 2 O (1), [H4L 1 = methyl-N(CH 2 PO 3 H 2) 2 ] and Cd 2 (H 2 L 2) 4 (2), [H 4 L 2 = n-propyl-N(CH 2 PO 3 H 2) 2 ] were synthesized and characterized. The Cu(II) ions in complex 1 are octahedrally coordinated by four oxygen atoms from two chelating ligands and two phosphonate oxygen atoms from two neighboring Cu(H 3 L 1) 2 units. The Cu(H 3 L 1) 2 units are interconnected by bridging phosphonate groups, forming a 2-D metal phosphonate layer. The structure of complex 2 contains two unique Cd(II) ions octahedrally-coordinated by six phosphonate oxygen atoms from four H 2 L 2 diphosphonate anions. Corrosion inhibition performances of 1 and 2 were also compared with each other in order to study the effect of combinations of externally added Cd/H 4 L 2 and Cu/H 4 L 1 (1:1 ratio) on corrosion rates of carbon steel. It was found that at pH 3.0, Cd/H 4 L 2 or Cu/H 4 L 1 combinations do not have noticeable corrosion inhibition efficiency for carbon steel. In contrast, at pH 7.0, higher corrosion inhibition efficiency was achieved for Cd/H 4 L 2. Physical characterizations such as scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were applied to study the corrosion specimens and film material.

The introduction of air into the drilling fluid used for geothermal aerated fluids drilling operations brings with it an increased potential for the corrosion of the materials that it comes into contact with, particularly the downhole tubulars and the surface equipment involved. It is therefore recommended that a corrosion control program be prepared when geothermal aerated fluids drilling operations are involved and this usually entails the monitoring of the level of corrosion and the introduction of corrosion inhibitors and other related chemicals into the drilling fluid. This paper presents the corrosion control programs that have been put in place in selected projects in the Asia Pacific region that have utilized geothermal aerated fluids drilling and evaluates their effectiveness in addressing the level of corrosion in these operations. It also provides the common practices, equipment and materials used when corrosion control is utilized as well as recommendations as to how the...

The high-temperature corrosion rate of boiler tubes was studied as a function of inhibitor concentration, time, and temperature in the absence and presence of fuel ash. Samples of steel tubes were taken from boilers that operate in Northern Baghdad Station for Electric Power Generation. Fuel ash was collected from the boiler combustion chamber, as well. Normal and nano-MgO were used as a corrosion inhibitor in different mixing ratios. A weight loss technique was used to evaluate the corrosion rates, while scanning electron microscopy was used to study the surface morphology. It was seen that corrosion rates increased with both time and temperature, and decreased with the addition of inhibitors. The maximum inhibitor efficiency was 81 %, obtained via using nano-MgO at mixing weight ratio 2:1, 600°C, and 10 h. The Presence of fuel ash had harmful effects on the steel surface.

Corrosion of A106 carbon steel in anoxic 30 wt.% monoethanolamine-based solutions (one example of a corrosive solvent for post-combustion CO2 capture) with CO2 loadings ranging from 0.24 to 0.53 mol CO2/mol amine is investigated. Results show that the corrosion and formation of a protective layer of corrosion products on the A106 surface are strongly CO2 loading-dependent. That is, initial corrosion is accelerated with increased CO2 loading. However, the formation of chukanovite and subsequently siderite, which dramatically inhibits the corrosion, was promoted with increasing CO2 loading. Chukanovite is a metastable intermediate corrosion product which transforms into siderite. Possible mechanisms are discussed.

Solvent degradation and metal corrosion are critical concerns of a post-combustion CO 2 capture process. Systemic analysis indicated that oxidation, nitrosation, and corrosion reactions occur or initiatethrough a radical reaction and thus addition of a radical scavenger is expected to work effectively to avoid these reactions. Here, for the first time, a multifunctional organic compound (CAER additive) has been evaluated as an inhibitor. The corrosion rate of A106 in 5 mol/kg MEA was lowered by one order of magnitude when 5mM inhibitor was added. Oxidation of 5 mol/kg MEA was monitored based on accumulation of formate concentration in the solution and formate levels were below the detection limit when CAER additive was present. Furthermore, the same additive was found to inhibit nitrosation of 5 mol/kgmorpholine with 100 ppm of NO 2 gas by 91% in 6 h.

The hydrolytic stability of lanthanide and actinide selective mono-and polyphosphonate-functionalized mesoporous zirconium titanium oxide adsorbents has been investigated in nitric acid solutions. Hydrolytic degradation of the surfaces, as measured through the fractional loss of phosphorus and elements of the oxide framework, increased by more than an order of magnitude as the nitric acid concentration was increased from 0 to 2 mol/L. The unfunctionalized parent oxide suffered considerable dissolution in 2 mol/L acid over a period of 72 h. Under identical conditions, the fractional Zr and Ti release was reduced to 1 × 10 −2 for monophosphonate functionalized hybrids and reached as low as 1 × 10 −6 for trisphosphonate functionalized variants. The bisphosphonates showed intermediate values. The leaching of P, Zr and Ti was found to be incongruent with the Zr leaching to a lesser extent implying enhanced stability of the Zr−O−P bond. Quantitative analysis of the dissolution kinetics indicated a parabolic dissolution model with a rate constant in the range of 0.5−1.5 mg g −1 min −1/2 for the elemental leaching of P, Ti, and Zr. The leaching of Zr from the mesoporous matrix was relatively more complex than for the other elements with evidence of a leaching mechanism involving two processes. ToF-SIMS and DRIFT analysis demonstrated that after leaching in 2 M HNO 3 for 24 h, a significant proportion of grafted ligands remained on the surface. The oxide functionalized with amino trismethylenephosphonic acid, which had previously shown excellent 153 Gd 3+ selectivity, was demonstrated to have outstanding stability, with low fractional elemental losses and preservation of mesoporous texture even after leaching for 24 h in 2 M HNO 3. This suggests this particular hybrid to be worthy of additional study.

Recebido em 2/2/06; aceito em 12/6/06; publicado na web em 28/11/06 OPTIMIZATION OF THE ELECTROLYTIC BATH FOR ELECTRODEPOSITION OF CORROSION RESISTANT FeW -B ALLOYS. A study on optimization of bath parameters for electrodeposition of FeW -B alloys from plating baths containing ammonia and citrate is reported. A 2 3 full factorial design was successfully employed for experimental design analysis of the results. The corrosion resistance and amorphous character were evaluated. The bath conditions obtained for depositing the alloy with good corrosion resistance were: 0.01 M iron sulfate, 0.10 M sodium tungstate and 0.60 M ammonium citrate. The alloy was deposited at 12% current efficiency. The alloy obtained had Ecorr-0.841 V and Rp 1.463 x 10 4 Ohm cm 2. The deposit obtained under these conditions had an amorphous character and no microcracks were observed on its surface. Besides this, the bath conditions obtained for depositing the alloy with the highest deposition efficiency were: 0.09 M iron sulfate, 0.30 M sodium tungstate and 0.50 M ammonium citrate. The alloy was deposited at 50% current efficiency, with an average composition of 34 wt% W, 66 wt% Fe and traces of boron. The alloy obtained had Ecorr-0.800 V and Rp 1.895 x 10 3 Ohm cm 2. Electrochemical corrosion tests verified that the FeW -B alloy deposited under both conditions had better corrosion resistance than Fe-MoB .

The demand for improved reliability and prolong the lifetime of piping and pipelines has led to the development of various methods to protect piping and pipelines from corrosion attack, one of which is the use of inhibitors such as molybdate. Molybdate is a corrosion inhibitor that is non-toxic and environmentally friendly. The present paper aims to study effect of molybdate on corrosion behaviors of various regions in submerged arc API 5L X-52 steel welded joints including weld metal (WM), heat affected zone (HAZ) and base metal (BM) in a 3.5% NaCl solution. In this study, corrosion characteristics of welded API 5L X-52 steel pipelines were studied using Tafel polarization method by immersing the specimens in 3.5% NaCl solution with different percentages of Na 2 MoO 4 inhibitors, namely 0.1, 0.2, 0.3, and 0.4% combined with SEM microanalysis of corrosion products. Results show that HAZ seems to be the most susceptible region for corrosion attack, and this undesirable effect is associated with bainitic microstructure present in the region. The additions of molybdate have two effects. First, the corrosion rate decreases with increasing inhibitor concentration and secondly; the corrosion potential is shifted to the positive direction in the polarization curve. The molybdate inhibition of corrosion could be related to its ability to form passive film, and it is discussed in the present study.

The feasibility of using extract of Grewa Venusta (wild jute tree) root as corrosion inhibitor with mild steel was investigated using gravimetric and electrochemical techniques in 1.0 M hydrochloric acid. The inhibitor's concentration, temperature and time were varied in the range of 0-10% v/v at 2% v/v interval, 30-75 o C at 15 o C interval and 1-6 hours at 1 hour interval. Characterizations of the extract were done by quantitative method (AAS) and Gas Chromatography-Mass Spectrometry (GC-MS). Scanning electron microscope (SEM) was used to analyze the surface morphology of the samples. The synergetic effect of the inhibitor was evaluated by addition of halide ions (KBr-, KCland KI-). The results showed that corrosion rate increased with an increase in temperature, and decreased with an increase in inhibitor's concentration and time; maximum inhibition efficiency was 97.60% and 99.88% in the presence of KIaddition, and was assumed to occur via adsorption of the inhibitor molecules on the metal surface. The extract contains metallic elements such as calcium, magnesium, mono acetate (C5H10O4) and 4H-Pyrazole (C9H10F6N2S) that suppressed the anodic dissolution. The adsorption of the extract molecules on the mild steel surface obeys Langmuir adsorption isotherm. The results showed that the inhibitor acted as a mixedtype inhibitor.

The main purpose of this research was to establish the effectiveness of the V844* corrosion inhibitor for seawater on various metallic materials: carbon steel, aluminum and copper alloy at different concentrations via colloid formation. The changes in both physical and chemical properties of seawater, including pH, total hardness, alkalinity, total dissolved solids (TDS) and conductivity at different concentrations of V844 were assessed, too. The test procedure involves dissolving the V844 corrosion inhibitor (CI) powder provided by Magna International Private Limited in seawater to obtain a stock solution of 4% V844 in seawater, which was further diluted to obtain the remaining concentrations. The analysis of parameters begun when various metal species, polished beforehand, were placed into the solutions. The analysis was observed over a period of 26 days and a total of 9 sets of readings were obtained. From our observation and ear power stations burning fossil-fuels generating acidic rains, the pH can diminish to 6.

A failure analysis was carried out on an A213 T91 secondary superheater tube after 4 months of overhaul. The failure caused the 600-MW coal power plant was shut down. The investigation consisted of visual inspections, microstructure analysis, Vickers hardness test, x-ray diffraction, and ash fusion temperature test and ash content analysis. The failed tube had a thin-lip rupture with sharp edges and experienced a decrease in hardness in the area of lip rupture. The microstructure analysis shows the coarse carbide and some isolated voids. Corrosion products were detected in slag deposits, and nonuniform thin oxide layer in the inner wall of the tube was observed. It is concluded that the main failure of the failed tube was due to the formation of slag deposits on the outer surface of the tube wall. This formation has resulted in simultaneously occurring phenomena, which was the localized flue gas erosion followed by the rapid overheating of the tube. The formation of slag deposits was in consequence of the use of coal with lower ash fusion temperature than required coal ash fusion temperature for the power plant.

The effect of the new natural corrosion inhibitor known as an aloe vera (mannose–6– phosphate) on the corrosion inhibitor for mild steel in (1 wt. % NaCl) was investigated by using potentiodynamic polarization measurement. Obtained results revealed that this compound was very good inhibitor and behave better in NaCl solution. Polarization studies showed that the aloe vera behaves as mixed type of inhibitor for mild steel in sodium chloride solution. The inhibition efficiency reached (81.81%) at concentration of (75 μml).

The inhibition efficiency of Tween 20 in controlling corrosion of carbon steel in well water has been evaluated by weight loss method. Mechanistic aspects of corrosion inhibition have been studied by Polarization and AC-impedance spectra. The formulation consisting of 200 ppm of Tween 20 and 50 ppm of Zn 2þ gives 85% inhibition efficiency. A synergistic effect exists between Tween 20 and Zn 2þ. Polarization study reveals that Tween 20-Zn 2þ system functions as a mixed kind of inhibitor. AC impedance spectra reveals that a protective film is formed on the metal surface. FTIR spectra reveal that the protective film consists of Fe 2þ-Tween 20 complex and Zn(OH) 2. The formation of monolayer and hydrophobic nature were confirmed by AFM, FTIR and Contact angle measurements. The contact angle measurement confirms the hydrophobic nature of the protective film.

During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data.

The driving idea for the present work was to combine the effect of polyvinyl alcohol (PVA) as corrosion inhibitor with the distance between the anodic and cathodic elements of the galvanic cell, beside their area ratio, in scope of synergistic suppression of galvanic corrosion on Cu/Fe model couple, using weight loss method. The performance affecting galvanic corrosion process has been tested for three major factors affect the process:1. Four PVA inhibitor concentrations were selected to be (0, 1000, 4000 and 7000 ppm) in simulated cooling water.2. Two cathode: anode area ratios as 1:1 and 2.4:1.3. Two distances apart cathode – anode as 3 and 7 cm.Maximum corrosion inhibition achieved was 86% which indicates that increasing inhibitor concentration leads to decrease dissolution process followed hydrogen evaluation Cu electrode as cathode element in galvanic cell.

The corrosion inhibition of low carbon steel in1N HCl solution in the presence of peach juice at temperature (30,40,50,and 60)°C at concentration ( 5, 10, 20, 30, 40and 50 cm3/L)were studied using weight loss and polarization techniques. Results show that the inhibition efficiency was increased with the increase of inhibitor concentration and increased with the increase of temperature up to 50ºC ,above 50ºC (i.e. at 60 ºC) the values of efficiency decreases. Activation parameters of the corrosion process such as activation energies, Ea, activation enthalpies, ΔH, and activation entropies, ΔS, were calculated. The adsorption of inhibitor follows Langmuir isotherm. Maximum inhibition efficiency obtained was a bout 91% at 50ºC in the 50 cm3/L inhibitor concentration. The polarization curves show that peach Juice is a mixed inhibitor.

In the present work 316LN as well as 316 stainless steel (SS) coupons each of dimensions (0.025 • 0.018 • 0.006 m 3) in well-polished condition were used as two nominal electrodes which were immersed in the aerated solution of 0.5 M NaCl. Correlated current and potential electrochemical noise (EN) signals were collected at 1 Hz sampling frequency for 1 h daily over a period of 30 days. The detrended EN data were used to calculate the noise resistance (R N) as well as the spectral noise resistance at zero frequency (R SN o) values and other statistical parameters. To study the nature of pits and distribution of their diameters as well as depths, extensive observations of the pitted and the blank specimens were carried out using Confocal Laser Scanning Microscopy (CLSM). The current and the potential records of the two alloys showed distinct differences in their corrosion behavior. It was observed that within less than 4 h of immersion, 316SS showed signals indicative of unstable pitting and onset of stable pitting was noticed after 48 h of exposure. However, until about 24 h, 316LN showed just the random signals and unstable pitting was observed after 28 h. The signals clearly indicated continuous growth of the stable pits in 316SS as against the repassivation of the unstable pits in 316LN after 7 days exposure. It was observed that R N values showed a continuous decrease in the case of 316SS, but were quite stable in the case of 316LN over the exposure period. Concurrent to these observations it was observed that 316SS specimen was extensively pitted. The frequency distributions of pit diameters as well pit depths were observed to be highest at 10-20 lm and 5-10 lm, respectively. However, pits with as large as 70-80 lm diameter and as deep as 20-25 lm too were observed. No pits were observed in case of 316LN even after 30 days of exposure, an observation that corroborates well with the stable R N values. Thus, in the present investigation, the longterm tests using EN technique coupled with CLSM studies conclusively prove that many unstable pits initiated in 316SS turn into stable ones resulting in insidious localized corrosion attack whereas the unstable pits initiated in 316LN get passivated in the simulated coastal environment.

Tese (Doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico.Estudou-se a brasagem sem fluxo entre aço carbono e cobre buscando avaliar a influência dos materiais base, dos metais de adição, das atmosferas de brasagem e do ciclo térmico na qualidade final da junta brasada. As brasagens foram realizadas utilizando metais de adição convencionais contendo Ag-Cu, Ag-Cu-Sn e Ag-Cu-Zn-Sn na forma de arame, ou através de revestimento de Sn, pela técnica conhecida como união por fase líquida transiente. Alto vácuo, médio vácuo, nitrogênio e mistura argônio-hidrogênio serviram como atmosferas de brasagem. A qualidade da junta brasada com metais de adição convencionais pode ser avaliada pela presença de defeitos, tais como pequenos rechupes, falhas de enchimento e até mesmo a presença de trincas. A ocorrência destes defeitos depende da combinação metal de adição/atmosfera de brasagem e da temperatura de brasagem utilizadas. O alto vácuo mostrou-se como a melhor atmosfera de b...

In situ transmission Bragg edge measurements of the strain fields in an X70 steel were performed near fatigue cracks grown in air and in hydrogen. Through the use of a novel test chamber which is capable of pressurization with hydrogen gas, and amenable to neutron-scattering measurements, fatigue cracks were grown in X70 steel specimens at the NG-6 neutron-imaging beam line at the NIST Center for Neutron Research. The measured strain fields are presented and discussed in the context of proposed mechanisms of hydrogen-assisted fatigue crack growth.

The pitting behaviour of 316 stainless steel in NaCl solution was investigated using potentiodynamic (PD) and potentiostatic (PS) polarization. Tests with the mode change from PD to PS at potentials close to the pitting potential showed that the potential could play a role in the stable pitting by maintaining the pit stability product. The metastable pit growth was studied by changing the mode at potentials far below the pitting potential and by characterizing the first current density spikes. The results suggested that the cumulative electric charge density governs the metastable pit initiation as a critical condition.

ISEP Museum was founded in 1999. It stores the memory of industrial school dated from the second half of XIX century. The education, at that time, was very practical and the methodology was based on models and tools. The collections are formed by 3 main typological groups: objects, prints/drawings and photos, a total of about 10 thousand pieces. The complexity of this collection causes multiple challenges concerning to conservation and management subjects. Recently, the main concern focus on the objects, because the lack of technical interventions by specialists. For instance, the Grenet and Leclanché cells are two case studies that show the prominent need of a technical intervention. This article presents a historical contextualization of cells, their composition and the conservation state of their constituent materials. The obtained results will attend to clarify further conservation and restoration approaches.

A resistência à corrosão por pite tem sido correlacionada com as condições morfológicas da superfície: um acabamento superficial liso contribui para diminuir o potencial de iniciação de pites. Esse estudo teve por objetivo investigar a relação entre a resistência à corrosão por pite e a rugosidade em superfícies usinadas do aço inoxidável superaustenítico ASTM A744 grau CN3MN. As amostras fundidas sofreram um torneamento cilíndrico com diferentes combinações das condições de corte, resultando, assim, em diferentes padrões de rugosidade superficial. As superfícies das amostras, então usinadas, foram caracterizadas quanto à rugosidade e ao endurecimento. Após submetidas a um teste por imersão, que acelerava a corrosão, essas superfícies foram examinadas num esteroscópio, tendo sido, também, determinada a perda de peso devido à corrosão. Observou-se que as amostras exibiram diferentes comportamentos com relação à resistência à corrosão, de acordo com as condições de usinagem aplicadas....

The next generation of Concentrated Solar Power (CSP) plants are expected to operate at higher temperatures than those currently in use, for improved efficiency and reduced cost of power generation. Figure 1 is a proposed scheme fo r a CSP plant designed to operate at temperatures from 550 to 700 °C with Thermal Energy Storage at around 630 °C. With regard to the three main sections of the proposed plant including receiver, storage and power generator, degradation mechanisms that thr eaten structural alloys at elevated temperatures include thermal fatigue and creep as general threats to all sections of the system (Sarvghad et al., 2018; Sarvghad, Will, & Steinberg, 2018) . In addition, specific degradation mechanisms caused by liquid sodium as the preferred heat transfer fluid material, eutectic salts or metals as Phase Change M aterial (PCM) in the storage and supercritical CO2 Brayton cycle in the generator threaten the plant.