rss_2.0KOM – Corrosion and Material Protection Journal FeedSciendo RSS Feed for KOM – Corrosion and Material Protection Journal – Corrosion and Material Protection Journal Feed brassing of historical artefacts<abstract> <title style='display:none'>Abstract</title> <p>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 (Cu<sub>5</sub>Zn<sub>8</sub>). 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.</p> </abstract>ARTICLEtrue the mechanism of organic corrosion inhibitors through density functional theory<abstract><title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue failure of stainless-steel in caustic soda lines<abstract><title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue corrosion attack on the galvanised steel pipes of the fire protection system<abstract><title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue of temperature and thermal cycles on the corrosion mechanism of wrought AZ91D magnesium alloy in simulated sea water solution<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue corrosion properties of reinforcement concrete by corrosion inhibitors: A brief review<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue oxides as an indicating electrode for pH measurement in the human body<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue EFC books series announcement on the texture and corrosion characteristics of AA5083 alloy reinforced with CeO by friction stir processing<abstract> <title style='display:none'>Abstract</title> <p>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<sub>2</sub>) 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<sub>2</sub>) using friction stir processing, as it acted as a good corrosion inhibitor.</p> </abstract>ARTICLEtrue you lead historical artefacts safely stored?<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue synthesis and characterization of calcium phosphate-based coatings on AZ31 magnesium alloy<abstract> <title style='display:none'>Abstract</title> <p>This study aims to analyze the influence of process parameters used for hydrothermal synthesis of CaP coatings on their properties and to improve their corrosion resistance and biocompatibility compared to the substrat AZ31. The parameters monitored were deposition time, pH of the reaction mixture, and concentration of precursors in the reaction mixture. For the deposited CaP coatings on AZ31 magnesium alloy, the surface morphology and the number of structural defects were evaluated using scanning electron microscopy. Electrochemical corrosion properties were evaluated using polarization techniques in Hank’s solution. The results showed that the best properties were obtained for the sample prepared in a reaction mixture at 120 °C, pH 5 for a deposition time of 120 min, when the concentration of precursors in the reaction mixture was 0.30 mol/l Ca(NO<sub>3</sub>)<sub>2</sub>·4H<sub>2</sub>O and 0.28 mol/l NH<sub>4</sub>H<sub>2</sub>PO<sub>4</sub>. Under these conditions, the best electrochemical corrosion properties were achieved.</p> </abstract>ARTICLEtrue of process conditions for the preparation of a manganese-based coating on the surface of AZ31 magnesium alloy<abstract> <title style='display:none'>Abstract</title> <p>Manganese-based coatings on AZ31 magnesium alloy with Mg(OH)<sub>2</sub> interlayer were prepared by hydrothermal reaction under different process conditions (temperature, time, and concentration). The harsh reaction conditions provided coatings with defects. These defects enabled the corrosive environment penetrated to the magnesium alloy which impaired the corrosion properties of AZ31 alloy. Optimal conditions included a temperature of 120 °C, 0.25 M MnCl<sub>2</sub>, and a reaction time of 1 h. The prepared coating was mainly composed of Mn<sub>3</sub>O<sub>4</sub>, which consisted of nanosized crystals of polyhedral shape. Potentiodynamic polarization measurements showed that the coating had very good corrosion resistance in 0.15 M NaCl. Future work will focus on the potential use of the manganese-based coating in biomedical applications.</p> </abstract>ARTICLEtrue investigation on the influence of metakaolin, metaillite and steel slag as SCMs in mortar on the corrosion behavior of embedded steel<abstract> <title style='display:none'>Abstract</title> <p>With the aim of saving CO<sub>2</sub> in cement production, various approaches are currently being pursued in the development of new materials. One possibility is to reduce the ratio of clinker to cement by using supplementary cementitious materials (SCMs). Some SCMs like fly ash or granulated blast furnace slag have been used successfully in cement for a long time and their use is covered by standards. Since the availability of these materials cannot be ensured in the long term, alternative additives are also being tested. The results presented here were obtained as part of a joint research project that was carried out in cooperation with the Bauhaus University Weimar. In this study, three different SCMs are investigated with regard to their effect on the corrosion of steel embedded in mortars: A metakaolin, a metaillite, and a modified steel mill slag were each tested at a proportion of 30 wt.% in a CEM I reference cement. In the two-stage tests, the passivation behavior of steel in mortars was first investigated in electrochemical tests. Based on this, tests were carried out in leached solutions of the different binders with different Cl–/OH– ratios.</p> <p>The results show that all the blended types of cement investigated provide passivation of the steel in mortar. The use of the calcined clays metakaolin or metaillite resulted in higher polarization resistances and lower passive current densities as well as increased electrical resistivities, especially for metakaolin. The steel in mortar with the steel mill slag showed comparable electrochemical behavior to the OPC mortar. The tests in leached solutions slightly indicate a higher corrosion-inducing Cl–/OH– ratio when using metakaolin or steel mill slag.</p> </abstract>ARTICLEtrue marks of phonograph cylinders from Tesař’s opera collection<abstract> <title style='display:none'>Abstract</title> <p>Phonograph cylinders are the oldest commercially available recording media and are an valuable part of cultural institutions’ collections. Even though they are an essential part of sound history, they have long been overlooked as a relatively chemically stable media. The only degradation mentioned in the literature was a whitish cover, traditionally appointed to microbiological growth. In our study, we focused on unravelling the issue of these degradation products. A selected collection from the National Museum – Czech Museum of Music was subjected to microbiological and analytical examination via digital microscopy, FTIR spectroscopy, colourimetry and SEM-EDS analysis. From the results, some of the degradation pathways were proposed. The results also help us to focus future research and suppress the degradation so that the cylinders stay longer in conditions fit for digitisation and overall archivation.</p> </abstract>ARTICLEtrue assessment of a bronze equestrian statue exposed to urban environment<abstract> <title style='display:none'>Abstract</title> <p>This paper presents the characterization of the conservation state of a bronze equestrian statue exposed outdoor, through an in-situ, multi-analytical, and non-invasive approach. The artefact under study is a bronze equestrian statue, devoted to Alfonso La Marmora, placed in an urban environment in the city of Turin. The investigation was carried out in the framework of a restoration intervention, with the principal aim of characterizing the overall conservation state of the sculpture to provide the conservators with information useful to develop a tailored restoration plan. X-ray fluorescence spectroscopy (XRF) was carried out for the identification of the elements present in the artefact alloy, showing that the statue was made using mainly two bronze alloys. Electrochemical Impedance Spectroscopy (EIS) was performed to study the corrosion mechanisms and to define the protective effectiveness of the patina present on the surfaces. Eventually, Raman spectroscopy (RS) was performed to characterize the chemistry and microstructure of the corrosion products, mainly identified as sulphates. The combination of these techniques allowed to confirm the presence of wax layers from previous restoration work, still capable to protect the metal substrate against corrosion. In addition, it was possible to correlate the conservation state to the exposure conditions and location on the statue.</p> </abstract>ARTICLEtrue studies on the corrosion inhibition of mild steel by 1-(phenylamino-1,3,4-thiadiazol-5-yl)-3-phenyl-3-oxopropan complemented with DFT Modeling<abstract> <title style='display:none'>Abstract</title> <p>1-(Phenylamino-1,3,4-thiadiazol-5-yl)-3-phenyl-3-oxopropan (PTPO) was selected as the investigated material for studying the protection performance for mild steel in 1 mol L-1 hydrochloric acid solution. The inhibitor was assessed using weight loss measurements complemented with morphological analytical techniques and density functional theory (DFT) modelling. The PTPO demonstrated significant inhibitive efficacy of 95.4% in the presence of 500 ppm at 303 K. The protection efficiency increases with the concentration increasing from 100 to 500 ppm, and no significant effect after 500 ppm. Furthermore, gravimetric findings reveal that the protection efficiency at 500 ppm PTPO increases with immersion period and increasing temperature (303-333 K), due to the effective adsorption of PTPO on the mild steel surface, and the protection efficiency value is 95.8% at 48 h of exposure and 95.4%, 95.4%, 95.7% and 95.9% at 303, 313, 323 and 333 K, respectively. The adsorption of PTPO on the mild steel surface obeyed the Langmuir adsorption isotherm model and revealing the mode of chemisorption adsorption. According to the DFT calculations, protection by PTPO is essentially performed by the heteroatoms in the inhibitor molecules which represented the adsorption sites, and the aromatic rings increase the electrostatic interaction between the PTPO molecules and the mild steel surface. The surface morphological studies, weight loss measurements, and DFT computational studies are in good agreement and that the selected corrosion inhibitor is adsorbed on the mild steel surface to form a protected layer on the surface of mild steel against the hydrochloric acid solution.</p> </abstract>ARTICLEtrue effect of acetic acid and NO for objects made of lead and its alloys; indoor corrosive environments in museums and depositories<abstract> <title style='display:none'>Abstract</title> <p>Complex corrosion simulation to evaluate synergistic effect have to cover large number of factors. To do so, environmental and corrosion datasets collected by monitoring sites of interest have been used to tailor complex artificial ageing of lead and lead alloys, using lead, tin and tin-lead coupons. Material composition was based on objects of interest which are tin-lead alloy based although naming lead objects is used widespread for vast of them. To evaluate results corrosion rate based on weight loss, phase composition of corrosion product and colour change of the coupon surface were utilized. For thin corrosion layers formed micro Raman and FTIR did not provide suitable results, and GIXRD have been used.</p> <p>Although limited number of conditions were used for the simulations, synergistic effect was observed for lead under specific conditions. Synergistic effect do occur on lead when exposed to NOX and acetic acid fumes of relatively low concentrations (18 µg·m-3 and 500 ppb respectively).</p> <p>In addition, there is grouping of colourimetric data collected according to test regimes – phase composition of corrosion product respectively. This information albeit preliminary suggests that colourimetric spectroscopy may be suitable as fast and easy corrosion monitoring.</p> </abstract>ARTICLEtrue of the welded joint of austenitic steel NEUTRONIT A 976 SM in the corrosive environment of boric acid<abstract> <title style='display:none'>Abstract</title> <p>The paper deals with the influence of the operating environment on the safe resistance of the welded joint of the construction material used in the nuclear power industry in the production of spent nuclear fuel containers. This material contains a higher percentage of alloying boron and is used as a shielding construction material for neutron and gamma radiation. It is used to produce baskets for spent nuclear fuel containers. When the containers are being filled, the welded joint of the basket structure are briefly exposed to an aqueous boric acid solution. The aim of this work was to determine the effects of exposure to the corrosive boric acid environment on the mechanical properties of the material. Tensile tests on the original weld and post weld exposure in H<sub>3</sub>BO<sub>3</sub> and corrosion cracking tests on unexposed welds were performed. The evaluation of the results revealed that the exposure to the corrosive environment of boric acid did not significantly affect the strength characteristics of the tested material NEUTRONIT A 976 SM.</p> </abstract>ARTICLEtrue of the diffusion coefficient calculation on predicting FeB boride layer thickness<abstract> <title style='display:none'>Abstract</title> <p>In this study, a single-phase boride layer thickness Fe<sub>2</sub>B is predicted on two different substrates (Armco iron and XC38 steel) by following the integral method. This method is a mathematical model based on a system of differential algebraic equations that help to deduce the diffusion coefficient, which is the key factor on predicting the layer thickness. Literatures cover different diffusion coefficients for each substrate, albeit researchers usually extract from experimental data, variations of growth rate constants within only one time treatment and deduce the diffusion coefficient from them. This deduction is done via an estimation of a frequency factor and an activation energy from the growth rate constants. Therefore, our main aim is to illustrate the impact of the deduction of the diffusion coefficient on predicting the boride layer thickness. Lastly, the impact with and without incubation time on the boriding kinetics of both substrates was also examined.</p> </abstract>ARTICLEtrue of glass dealkalization on the quality of adhesion of bonded materials<abstract> <title style='display:none'>Abstract</title> <p>The aim of this paper is to determine the effect of dealkalization of the glass surface on the quality of adhesion of bonded parts to the glass. Most of the available studies on glass dealkalization tend to focus only on the properties of the glass itself and the processes taking place in the surface layers of the glass. However, in practice focused on adhesion, the cleanliness of the glass surface is an important factor, which is influenced, among other things, by dealkalization. In this work, the influence of the use of gaseous SO<sub>2</sub> in the furnace on the composition of the glass surface and on the resulting adhesion is assessed. Regarding the deterioration of the adhesion quality between the glass treated with SO<sub>2</sub> gas and the adhesion promoter, the cleaning efficiency of the glass surface was further tested, according to the results of the cross-cut test.</p> </abstract>ARTICLEtrue