Volume 66 (2022): Edition 1 (January 2022)

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.

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.

This paper is focused on the problematics of weld joint corrosive degradation in the boiler water environment. The boiler water is commonly used in power industry. The corrosion experiment simulated the boiler water environment during shutdown, when chemicals may be concentrated in the deposits, or as a result of evaporation. The corrosion experiment was performed on heterogeneous weldments made of P265GH//X6CrNiTi18-9 steels in the environment of stagnant boiler water with the addition of NaCl for 53 days. The data showed only minimal weight losses, and small changes in the measured fracture toughness of the welded joint. At the same time, a tendency for a mechanical weakening of the welded joint with the increasing aggressivity of the boiler water environment was observed. The metallographic analysis was performed to describe the nature of corrosive degradation.

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 H₃BO₃ 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.

In this study, a single-phase boride layer thickness Fe₂B 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.

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.

The boronizing kinetics of AISI 316L steel has been analyzed by employing five prediction models. The boron diffusion coefficients as well as the growth rate constants in the FeB and Fe₂B phases were firstly evaluated in the range of 1123-1223 K. Afterwards, the values of boron activation energies in FeB and Fe₂B were secondly deduced by adopting the Arrhenius relationships.In addition, the prediction models have been validated experimentally for two boronizing conditions (1170 K for 1.6 h and 1210 K for 1.1 h). The predicted results were deemed very concordant with the experiments. Furthermore, advantages and limitations about the applicability of these models were also discussed.

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.

The aim of this work was an experimental comparison of different types of packaging paper, determining the effect of packaging material properties in combination with storage conditions on the purity of glass surface and the related quality of adhesion of bonded materials. In the automotive industry, the quality of adhesion is a key factor, as automotive glass must meet the safety requirements. During the experiments, the glass sheets were wrapped in four types of paper and stored according to the conditions that are common in a real production. The research was focused on the influence of different composition of packaging papers on the resulting adhesive properties of glass sheets. According to the results obtained in this work, it can be stated that during the storage there is an interaction between paper and glass. According to XRF analyzes, ongoing corrosion of the glass can be inferred. The resulting adhesion was assessed based on a peel test, which took place under defined conditions given by standard customer specifications. It has been observed that the negative effect of unsuitable paper increases over time. For optimal adhesion it is necessary to emphasize the packaging materials and the storage conditions of the glass. The results and knowledge achieved in this work can significantly improve the quality of production in which a material is glued to the glass surface.

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.

New trends in the automotive and construction industries are leading manufacturers to develop new materials with added value. In this article, we deal with the introduction of such a material, namely a silver-based emission coating, which is used in both architecture and the automotive industry. Silver-based coating thus makes it possible to increase the driver’s comfort, or to increase the comfort of working in the office on hot steamy days. This coating changes the transmittance of IR radiation from or to the building, or from or to the car. The coating is based primarily on the presence of layers of silver, which are able to provide the primary functions of modulation of incoming and outgoing radiation. Silver-based coatings can also be used to heat, for example, car windshields. The production of a silver-based coating is very demanding and sensitive to the formation of coating defects. In this article, we discuss common coating defects and discuss their possible origins.

AA2024-T351, a heat treatable aluminum alloy, has a high strength to weight ratio and good fracture resistance and has application mainly in the aircraft and aerospace sector. However, the alloy is susceptible to high corrosion because of the secondary phases (Al₂Cu) present in the matrix. With an objective to increase the corrosion and wear resistance, Friction Stir Processing is applied to engineer the morphology and dispersion of the Al₂Cu phase in the alloy. The friction stir processing trials are performed by varying the tool rotation speed, tool traverse speed, and shoulder diameter, as the properties of the friction stir processed region depend on the proper selection of process parameters. A hybrid linear-radial basis function model is developed to explore the effect of tool rotation speed, tool traverse speed, and shoulder diameter on the grain size, microhardness, corrosion rate, wear rate, and corrosion potential of the friction stir processed AA2024-T351 alloy. The predominant corrosion mechanism and wear regimes in AA2024-T351 alloy are understood from the characterization study on the surface morphology and elemental analysis of the corroded and worn specimens. The optimum friction stir processing parameters that improve the grain refinement, microhardness, corrosion resistance and wear resistance of AA2024-T351 alloy are established.

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.

In the present investigation, corrosion inhibition assays of the terephthalaldehyde-derived Schiff base of low-carbon steel have been performed in a 1.0 mol L⁻¹ hydrochloric acid solution. Weight loss measurements were applied to investigate the corrosion inhibition efficacy of Schiff base as an inhibitor. The highest inhibitive efficacy was achieved at a select concentration of 500.0 ppm for the tested inhibitor. The Langmuir adsorption isotherm model was applied to portray the adsorption inhibition mechanism. The variation in the activation energy value in the presence of synthesized inhibitor indicates the types of interactions between the inhibitor molecules and low-carbon steel surface. Scanning electron microscopy analyses proved the adsorption of inhibitor molecules on the low-carbon steel surface and through form a film that protects the metallic surface from corrosion. Furthermore, the relationship between inhibitive efficacy and the inhibitor molecule structure was studied theoretically through density functional theory (DFT). The experimental and theoretical findings reveal compatible harmony between them.

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, NO_x. 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.

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.

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).

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.

Cellulose nitrate in the form of collodion has been used as a light-sensitive layer since 1851. As such, collodion photographs are often found in cultural institutions. Because of its organic structure, it is susceptible to microbiological contamination and, therefore, a need for disinfection may occur. In such cases, the disinfection method must be effective and non-destructive towards the material and restorer. Since all tried disinfection methods were proven effective by cooperating microbiologists, the non-destructivity against material became the primary concern. Model samples were prepared, disinfected, and artificially aged; to observe any possible change in properties on a long-term scale. The properties measured were: change in colour, change in the content of nitrogen and change in the degree of polymerisation obtained by viscometric measurements. From the results, we could select a disinfection method that did not pose any measurable threat towards the collodion light-sensitive layer and, therefore, can be used in practice by restorers.

The article deals with the real defect, a crack that occurred on a part of the steam pipeline of the separator and the steam superheater of the turbo-generator in the V2 nuclear power plant (NPP) in Jaslovské Bohunice. The damage was caused by the mechanism of erosion-corrosion, which led to a reduction of the pipe wall with the critical thickness. The main cause of the failure was identified to be the usage of unsuitable steel, instead of the required steel EN 10028-2, during the reconstruction of the pipeline.

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 SO₂ 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 SO₂ gas and the adhesion promoter, the cleaning efficiency of the glass surface was further tested, according to the results of the cross-cut test.

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.