The inhibitory ability of the boiling extracts from the aerial parts of Chenopodium album and Polygonum aviculare on the corrosion of mild steel EN Fe37-3FN in 0.5 M hydrochloric acid medium was investigated using electro-chemical methods and EIS. It was shown that the addition of 90 mg/l of the Chenopodium album aerial parts extract reduces the corrosion rate by 35%, and that of of 1 g/l and more – by 75%, whereas the addition of 120 mg/l of the Polygonum aviculare aerial parts extract reduces the corrosion rate by 40%, and that of of 1 g/l and more – by 85%. The adsorption of the extract components on a steel surface follows the Langmuir adsorption model, and the nature of adsorption is physical. The Chenopodium album and Polygonum aviculare aerial parts extracts show themselves as perspective and environmentally friendly substances for reducing the steel corrosion rate in acidic environments.
The study examines the influence of the composition and additives in beeswax mixtures used in historical ceroplastics on their long-term stability. Based on analyses of historical recipes and research into collection items, experimental wax mixtures with various additives (lard, Venetian turpentine, dammar, paraffin, pigments) were prepared and subsequently subjected to workability tests, measurements of physical properties, and artificial aging. The results show that additives significantly affect not only the rheological properties of the mixtures, but also their chemical and thermal stability. While some additives contribute to increased stability, others (especially combinations of pigments with reactive components) can initiate degradation processes. The study provides new insights into historical technologies and provides a basis for the formulation of methodological recommendations in the field of preventive conservation and restoration of ceroplastic works.
This study investigates the formation of zinc oxide (ZnO) layers on zinc substrates under various environmental conditions and their characterization. Zinc samples were subjected to controlled exposure regimes including aqueous solutions and water vapour environments to stimulate the formation of ZnO. The resulting layers were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM/EDS), and optical microscopy. The analysis reveals correlations between exposure parameters and layer morphology, thickness, and phase composition. The study identifies key factors affecting ZnO layer quality and proposes pathways for optimizing these layers for potential sensing applications.
Abstract This review paper studied the potential of using metal oxides as a green corrosion inhibitor for different alloys in various aggressive corrosive environments. Metal oxides are widely used for various applications such as sensors, environmental remediation, nanoelectronics devices, solar cells, biomedical applications and clean energy production due to their unique electronic structure. Metal oxides exhibit low corrosion inhibition efficiency when used as corrosion inhibitors in bulk form but attain significantly higher inhibition efficiencies when used in nanostructured form. Increasing the concentration of the metal oxides significantly reduced the corrosion rate and enhanced the corrosion inhibition efficiency for various samples studied under different operating conditions due to the increased surface area to volume ratio as well as the enhanced adsorption of the oxides onto the surface of the substrates, thereby reducing the corrosion rate by decreasing the available sites for the dissolution reaction. However, the challenges of agglomeration and poor dispersion of nanoparticles were frequently reported at higher concentrations which contributed to observed reduced efficiencies. Barrier protection, electro-chemical inhibition, synergistic interactions with other inhibitors, self-healing properties, adsorption and passivation have been widely reported as the mechanism by which metal oxides protect the various substrates studied. The chemical and thermal stability of metal oxides in aggressive salt environments is a comparative advantage over other traditional organic and green inhibitors. The various methods of synthesis and characterization of metal oxide nanoparticles as well as their cost and associated safety and environmental concerns have also been discussed.
This study evaluates the suitability of selected lignocellulosic papers as packaging materials for the long-term preservation of diazotype records. To assess possible packaging materials, five types of paper were tested under artificial ageing conditions that simulate long-term storage. Their optical, chemical, and mechanical properties were systematically analysed. The results revealed that two tested alkaline papers exhibited high optical and mechanical stability, alkaline pH values, and limited release of harmful volatile organic compounds. Whatman No. 1 unsized paper showed good optical stability and chemical neutrality. Two types of acidic paper sized with rosin performed poorly, releasing volatile acids and displaying low mechanical resistance. In general, both alkaline papers are recommended as packaging materials for the preservation of the diazotype, while Whatman No. 1 represents a possible compromise. Acidic papers are unsuitable because of their acidity, the emission of harmful degradation products, and their insufficient durability.
A novel approach for synthesizing nickel (II) oxide (NiO) nanoparticles was developed by chemically precipitating nickel (II) chloride (NiCl 2 ) derived from dissolving pure solid nickel in concentrated hydrochloric acid. The synthesized nano-particles were then characterized and evaluated as a corrosion inhibitor for mild steel. Structural, morphological, and thermal properties were analyzed using XRD, FTIR, TEM, SEM-EDX, TGA/DTA, and DSC techniques. The nanoparticles exhibited a highly crystalline structure with an average crystallite size of 23.03 nm, which was consistent with TEM analysis showing individual particle sizes between 10.02 and 28.50 nm. Thermal analysis revealed a significant decomposition event at 519.4 °C, indicating high thermal stability. The corrosion inhibition potential was assessed on mild steel specimens coated with an epoxy resin containing 1 wt. % NiO nanoparticles and immersed in a 3.5 wt. % NaCl solution. The results demonstrated a substantial decrease in corrosion rate with the addition of NiO. The epoxy-1 wt% NiO nanocomposite coating provided the highest inhibition efficiency compared to the sample coated with only epoxy resin and the uncoated sample reaching 91.0 % and required a higher activation energy to initiate corrosion compared to both uncoated and neat epoxy-coated samples. This study confirms the successful synthesis of stable, crystalline NiO nanoparticles via a novel chemical precipitation method and establishes their superior performance as an active component in epoxy coatings for robust corrosion protection of mild steel.
This study presents the material composition of laminated artworks created on the territory of today’s Czech Republic between 1950 and 1990. During a field survey, more than 60 objects were evaluated, and for 48 of them, the chemical composition of the resin matrix was determined using analytical methods. Approximately one third of the artworks were made of epoxy resins, despite the fact that their use was considered less suitable at that time compared to unsaturated polyester resins. For laboratory testing, model samples were prepared from selected unsaturated polyester (UP) and epoxy (EP) resins. The influence of abrasive blasting with different media and the application of selected organic solvents on the surface properties of the resins was studied. Laser confocal microscopy revealed that resin hardness affects the surface topography after blasting, with the lowest roughness observed after blasting with limestone. Among the solvents tested, acetone was found to be the most aggressive toward the polymer matrix. The findings contribute to the optimisation of conservation strategies for laminated artworks exposed in outdoor environments.
Abstract Cast aluminum alloys are one of the most widely used structural materials in electrical engineering due to their good mechanical properties, high thermal and electrical conductivity. Passive Al 2 O 3 layer formation on the aluminum surface reduces its electrical conductivity. Thus, the Ag coating electrodeposition on the aluminum substrate material allows increasing the electrical conductivity. The coating quality depends not only on the composition and on the quality of the electrolytic bath and technological parameters of the deposition, but a very important factor is the surface material pre-treatment prior to coating. In this study, the causes of the defect occurrence in the form of blisters on the Ag coating surface were analyzed. Blistering is a characteristic sign of local low adhesion strength of the coating to the substrate. Microscopic analysis showed the presence of AlSi fragments between the coating and the substrate, which were formed during machining of the Al casting surface. The difference in electrical conductivity between the AlSi particles and the aluminum matrix created an inhomogeneous field during electroplating, which led to the formation of defects in the coating. The presence of pores on the Al casting surface, resulting from low-pressure casting conditions, may also have contributed to defects formation in the coating.
Carbon steel has long been used in storing the saline water that results from oil washing in the oil industry. However, a high corrosion rate is reported, resulting in significant economic losses for oil companies. In the Middle East oil field, the temperature touches 50⁰C in Summer, causing increasing in corrosion rate for saline water steel storage tanks and pipes. In the present work, abundantly available wheat straw was used to prepare a cost-effective silicate inhibitor. The high inhibition efficiency of up to 94 % decreased the corrosion rate from severe corrosion for no-inhibitor specimen to close to low corrosion category for optimum inhibitor concentration specimen. The mechanism of the inhibition effect is the formation of a chemically adsorbed layer on the steel surface, which is successfully described by Langmuir isotherm. Additionally, at high concentrations of nano-silica, complex aggregates might form and be physically adsorbed on the surface of steel above the chemically adsorbed nano-silicate monolayer.
Abstract The topic of this work was the investigation of an alternative brassing technique consisting of electroless zinc plating of a copper object in a strongly alkaline solution and subsequent annealing to achieve a characteristic brass appearance. Within the scope of the work was the determination of the mechanism of zinc deposition on the copper surface, the optimisation of the NaOH concentration (30 and 40 wt. %), time of deposition (5-120 min), as well as temperature (150 and 200 °C) and annealing time (15 – 60 min). Electrochemical methods (potentiodynamic curves and open-circuit potential), metallography, X-ray diffraction (XRD), and glow-discharge optical emission spectroscopy (GD-OES) were used to study the brassing mechanism. Electrochemical measurements have shown that zinc powder significantly decreases the surface potential of copper to the value of zinc itself and also acts as a reducing agent. The diffusion of zinc in copper was found to occur during the primary deposition of zinc with the formation of the γ phase (Cu5Zn8). The optimal NaOH concentration is 40 wt.% and the deposition time is 60 min. The optimal conditions of annealing are 200 °C and 60 min. The primary γ phase is transformed during the annealing process into β and α phases.
Abstract The paper deals with the case studies of stainless steel piping corrosion in caustic soda transfer lines at a hydrocarbon processing plant, in the Asian region. The lines were in service of transferring the caustic soda solution from the storage tank farm to different process units, for subsequent use in reaction vessels. To maintain a minimum temperature of the fluid to avoid its precipitation, the lines were accompanied by a steam heat-tracer, throughout the line route. The material of construction (MOC) of the line was stainless steel type 316. After a period of about 3.5 years, 2” caustic line suffered fluid leakage, which was noticed through significant salt accumulation over insulation at one location. A valve was also noticed to leak through a weld at a 1.5” distribution line. The affected components were removed from service and subjected to detailed inspection and laboratory investigation, using advanced tools of metallurgical analysis and characterization. It was found that leakage in 2” line had occurred due to poor workmanship used during the repair of a manufacturing defect at the affected location and leakage of the valve had taken place due to the use of improper welding practice (in the case of subjected weld). In addition, the significant role of metallurgical defects in the parent metal was also disclosed to result in the observed failures. In addition, the contribution of process excursions can’t be completely ruled out. Finally, remedial measures are given to avoid the recurrence of such failure.
Abstract Organic corrosion inhibitors have been widely used to prevent and mitigate the damaging effects of corrosion on metal surfaces. However, their underlying mechanisms of action and effectiveness are still not fully understood. In recent years, the use of density functional theory (DFT) has emerged as a powerful tool to investigate the interaction between organic inhibitors and metal surfaces at the molecular level. This review article provides an overview of the principles of DFT, its advantages and limitations, and its application to the study of organic corrosion inhibitors. The factors affecting the performance of organic inhibitors, such as molecular structure, functional groups, and metal surface properties, are discussed in detail. The interaction between organic inhibitors and metal surfaces, including the adsorption and desorption of inhibitors, the role of intermolecular forces, and the effects of pH and temperature, are also explored. Finally, the challenges and future directions in the development of organic inhibitors using DFT are highlighted, including limitations and challenges in using DFT and potential avenues for further research. Overall, this review demonstrates the potential of DFT to provide valuable insights into the mechanism of organic corrosion inhibitors and to guide the development of new and more effective inhibitors for the protection of metal surfaces.
Abstract Galvanised steel serves as a base material for pipelines in fire protection systems. However, this system is known for its occasional corrosion failures. The Systems with residual water and oxygen access contribute to formation of macrocells due to different aeration, which can lead to severe damage of the pipes. The aim of this work was to investigate the cause of localized corrosion on the galvanised pipes designated for the fire protection system. The results proved that the main cause of the fire protection pipe system was the residual water in the pipe. The influence of differential aeration on the corrosion of zinc and steel was studied by resistometric technique and showed no effect on the failure of material.
Abstract This study focuses on the evaluation of historical acid blackening of steel in terms of their applicability to historical objects, such as tin-soldered multi-barrelled firearms, where the alkaline bath blackening method cannot be used. The acid blackening method was also compared with the alkaline hot bath blackening method used nowadays, both on the conversion layer itself and in combination with a preservative agent. The procedures were tested on low carbon steel samples and fragments of damaged historic steel barrels. The quality of the surface treatment was evaluated both in terms of visual appearance and corrosion resistance. The corrosion properties were evaluated both by a condensation chamber test and by electrochemical methods such as polarization resistance measurements or electrochemical impedance spectroscopy.
Abstract Hexavalent chromium has dominated the corrosion inhibitor’s market as a benchmark alternative due to its unparalleled excellent corrosion inhibition properties. However, it was phased out because of its carcinogenic effects. Subsequently, many alternative inhibitors have been introduced into the inhibitor’s market but failed to meet the performance of this benchmark inhibitor. Recently, intelli-ion (AX1) was reported as a new alternative to hexavalent chromium based on Scanning Kelvin Probe (SKP) carried out on hot-dip galvanized steel (HDG) substrates for chromate and intelli-ion inhibitors. The intelli-ion system showed impressive performance at generation 1, with increased protection offered by the generation 2 product, showing no visible failure after 4 days test procedure. To further validate this, the cut edge corrosion performance of intelli-ion (AX1) and benzotriazole (BTA) was studied on galvanized steel specimen in 5wt.% NaCl solution using Scanning Vibrating Electrode Technique (SVET). From the SVET current density maps of AX1 (specimen A and B) vs. BTA (specimen C) after 24 h in 5 wt.% NaCl solution. The AX1 inhibitor had a better overall cut edge corrosion inhibition performance than the BTA.
This study successfully conducted a comprehensive analysis of the AZ91D magnesium alloy, encompassing micro-structural, mechanical, and corrosion assessments. The microstructure consisted of primary α-Mg crystals and an aluminum-rich α-Mg/β-Mg17Al12 eutectic phase, with intermetallic phases predominantly precipitating at grain boundaries. The microhardness was quantified at 49.96 ± 1.76 HV. Thermostatic tests unveiled a noTab. increase in corrosion rates with rising temperatures, signaling reduced corrosion resistance at elevated environments. Conversely, thermos-cyclic tests showed relatively lower corrosion rates attributed to the accumulation of protective debris on the specimen surface, which could mitigate corrosion during temperature fluctuations. Electrochemical corrosion behavior revealed susceptibility to pitting corrosion at –1.204 V, limiting its application as a sacrificial anode in marine settings.
AA5083 alloy exhibits favorable resistance to corrosion and welding characteristics, making it attractive for application in the marine environment. However, pitting and intergranular corrosion of AA5083 is still troublesome. This study investigates the corrosion resistance and texture evolution of friction stir processed AA5083 alloy with Cerium Oxide (CeO 2 ) as reinforcement. The FSP trials were performed by varying the process parameters: tool rotation speed (TRS), tool traverse speed (TTS), and a constant shoulder diameter (SD). The fabricated surface composite (FSC) specimens were subjected to microstructure, microhardness, intergranular corrosion, and electrochemical corrosion analysis. The specimens were subjected to advanced analytical instruments such as TEM, EBSD, and XRD to study the microstructure and texture evolution. The results showed that the corrosion of AA5083 alloy in the saline environment is highly suppressed by reinforcing it with cerium oxide (CeO 2 ) using friction stir processing, as it acted as a good corrosion inhibitor.
The penetration and diffusion of chloride ions into reinforced concrete structures is the primary cause of steel reinforcement corrosion; thus, this work focused on demonstrating and reviewing the beneficial effects of green inhibitors and organic inhibitors on chloride-induced corrosion. Another motivation for selecting and testing these types of inhibitors was to investigate their effectiveness in greater depth using a variety of various scientific methodologies and a variety of very advanced laboratory and materials testing procedures. In this method, the chosen eco-friendly inhibitor (so-called green inhibitor) might be compared with at least a less hazardous inorganic inhibitor, which is also cheap and usually effective in mitigating iron corrosion in the given environment.
The human organism is under normal circumstances a stable system. The values of traceable chemical and biochemical markers change within a known and often very narrow range. In orthopedics an inflammatory disorder after the implantation can occur. The presence of such a problem demonstrates itself, even in the initial phase, in a drop of pH. A pH sensor, which would be temporarily allocated close to the implant, could therefore instantly indicate the origin of the inflammatory process. The behaviour of tantalum as a pH indicator was studied in this work. In the tested range of pH (4.5-7.5), the potential-pH dependence of this sensor was determined to be at the approximately Nernstian level –59 mV/pH. The main drawback was the long-term initial stabilization of the signal. The only meaningful detection method that could be used in practice is the electrochemical potential-pH dependence monitoring.
Abstract Indoor conditions have the greatest influence on the long-term storage of historical artefacts. The following text summarizes essential knowledge regarding the evaluation of the corrosivity of indoor atmospheres with an emphasis on the effect of the presence of volatile organic acids on corrosion of lead. It provides an overview of the information and resources necessary to decide whether lead storage conditions are safe and concludes by outlining a path to resolution if they are not.
