Abstract 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(NO3)2·4H2O and 0.28 mol/l NH4H2PO4. Under these conditions, the best electrochemical corrosion properties were achieved.

Abstract Manganese-based coatings on AZ31 magnesium alloy with Mg(OH)2 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 MnCl2, and a reaction time of 1 h. The prepared coating was mainly composed of Mn3O4, 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.

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.

Abstract With the aim of saving CO2 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. 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.

Abstract The aim of this paper was to evaluate the possibility of presence of the synergic corrosive effect between acetic acid and chosen air pollutants such as: Cl2, SO2, NaCl, H2S, NH3, NOx. The metals chosen for following experiments were lead and zinc as they are known to be sensitive to volatile organic compounds. Acetic acid occurs often at indoor environment, where other pollutants may be present. The idea was to describe the influence of other pollutants on increasing the corrosion aggressivity of atmosphere contaminated by acetic acid. Synergic effect was found on lead for following pollutants: sulphur dioxide, chlorine, ammonia and nitrogen oxides. And on zinc the found pollutants are: sodium chloride, sulphur dioxide, chlorine, hydrogen sulphide and nitrogen oxides.

Abstract Nuclear power is a significant source of clean energy that can be used to mitigate climate change. In the western world, the average life of light-water power-reactors is increasing because no new reactors are being connected to the grid. In order to extend the life of the existing reactors innovative materials are being considered for the fuel of the reactors. The newer materials would be more resistant to a loss of coolant accident and allow for longer times between refueling plus permitting overall extended burn-ups, which will make the reactors safer and more economical to operate. This never used before in reactor materials include cladding concepts such as: 1) coated zirconium alloys, 2) monolithic iron-chromium-aluminum alloys, and 3) silicon carbide composites.

Abstract There are still some challenges and issues related to the long-term usage of the material, despite the apparent and successful expansion in metallic orthopaedic applications and bone replacement. The goal of the current study is to use 2205 duplex stainless steels instead of 316L stainless steels in medical applications (DSS). The 2205 DSS is characterised by a decreased nickel content, which offers a benefit in medical applications by lowering the release of nickel ions in the body. It is made up of two-phase (austenite and ferrite) microstructures. Additionally, this alloy finds employment in a range of media due to its excellent mechanical strength, hardness, toughness, and corrosion resistance at an affordable price. There is a pertinent issue to take into account with these constraints because of the poor osteoconductivity and the risk of surface contact, which leads to severe corrosion of metallic implants due to the presence of body fluid. This review demonstrates how to modify the surface of DSS-2205 by coating it with hydroxyapatite/multi-wall carbon nanotubes using electrophoretic deposition (EPD) to enhance corrosion resistance, biocompatibility, and osseointegration. It also discusses the impact of the two most crucial EPD variables (potential and time) on the characteristics of the deposited layer in order to determine the best EPD variable values.

Abstract The pack-boriding kinetics of SAE 1020 steel has been addressed through utilizing four mathematical approaches in case of the formation of diiron boride layers. The values of boron diffusivities and activation energies in Fe2B were assessed in the interval of 1123 to 1223 K by using four models. Finally, the four models were experimentally verified by comparing the predicted results to the experimental value of Fe2B layer thickness determined at 1198 K for 6 hours. Finally, the simulated layers’ thicknesses agreed with the experimental result. In addition, similarities and differences observed in the models were also discussed.

Abstract 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.

Abstract The surface treatment of historical iron artefacts involves application of right conservation coating to the material to prevent further corrosion deterioration. Among common conservation agent of iron belong tannate coating, which is considerably preferred with the desired black appearance of the surface. In this work the new potentional conservation agent Metal Antik was studied. The change of this possible surface treatment was evaluated over time. The comparison between long-term exposed samples (15 years), short-term exposed samples (1.5 year) and fresh cured samples was done by spectrocolorimetry measurement. This was also compared to standard samples prepared with tannate coating. Surface analysis for all types of samples was done by μ-Raman spectroscopy. Results proved that effect of time changes the surface of coatings. It was demonstrated by colour change of surface and by formation of areas with local corrosion. Another study of Metal Antik in order to improve corrosion resistance is open.