Search results

The purpose of this paper is to focus on the investigation of nanomechanical behavior of new types of metal alloys protective coatings. For this purpose, poly(n-butylacrylate) was synthesized via activators regenerated by electron transfer-atom transfer radical polymerization and mixed with epoxy resins, and microcomposites.

Multi-layered coatings were applied on hot dip galvanized steel via a baker film applicator. Every layer containing the aforementioned copolymer differs in the proportion of the epoxy resin resulting in the production of a coating with a gradient from hard to soft from the substrate to the top. Nanomechanical performance is accessed via nanoindentation, providing information for structural and mechanical integrity, adhesion and resistance to wear.

The results reveal that through trajection of hardness mapping, the resistance is divided in three regions, namely, the polymer (matrix), interface (region close to/between spheres-shells) and spheres-shell regions.

The structural analysis, adhesion and mechanical integrity of the coatings are clearly demonstrated.

Magnesium-aluminum layered double hydroxides (LDH) with a platelet-like morphology were synthesized through a modified co-precipitation method. The purpose of this paper is to investigate calcined Mg-Al-CO₃ LDH (CLDH) as chloride ion traps.

The morphology and chemical composition of the synthesized materials were studied through UHR-SEM, EDS, FT-IR and XRD. The chloride ion adsorption was confirmed by XRD; the characteristic diffraction peaks of the reconstructed LDH structure were revealed, similar to the one before the thermal treatment process. The effect of varying the experimental conditions on the chloride ion adsorption, such as the initial target-ion concentration, the adsorbent material dosage, the solution temperature and the solution pH was also investigated.

The experimental data fitting revealed that the Langmuir equation is a better model on the basis of correlation coefficients (R²) and that the pseudo-second kinetic model can satisfactorily describe the chloride ion uptake.

The ability of Mg-Al CLDH to recover their layered structure upon exposure to aqueous sodium chloride solutions with concentrations up to 0.3 M (10,636 mg/L) through the chloride adsorption and the simultaneous rehydration process is clearly demonstrated.

The purpose of this paper is to focus on the investigation of mechanical and thermal properties of lignin/poly (ethylene oxide) (PEO) blends, intended to be used as carbon fiber precursor.

Softwood kraft lignin was modified via esterification using phthalic anhydride and then blended with PEO. The final lignin/PEO ratios blends were (w/w) 20/80, 50/50 and 80/20 for both unmodified and modified lignin. The structural, thermal and mechanical properties of the blends were investigated by Fourier transform infrared, differential scanning calorimetry and tensile tests, respectively.

The results revealed that modified lignin/PEO blend (20/80) exhibited enhanced elongation.

The structural analysis as well as thermal and mechanical properties of the produced blends are clearly demonstrated.

The purpose of this paper is to focus on the corrosion protection of magnesium alloy ZK10 by applying via the dip‐coating process an hybrid organic‐inorganic coating that contains nanocontainers of TiO₂ loaded with corrosion inhibitor.

The coating consists of cross‐linked polymers containing epoxy groups, conductive polymer polypyrrole as well as organic modified silicates. The morphology and the composition of the coating were examined with scanning electron microscopy and energy dispersive X‐ray analysis, respectively.

Corrosion tests via electrochemical impedance spectroscopy denoted that the incorporation of loaded nanocontainers improved the anticorrosion properties of the coating by increasing the impedance values in the low frequency range. Moreover, the surface of the aforementioned coating remained crack free after the exposure of the sample to corrosive environment.

The paper presents a new system which has been developed for the corrosion protection of magnesium alloy ZK10.

The study of nanoindentation as a reliable method to extract creep properties as well as for fundamental understanding of deformation mechanisms at small length scales is an open interesting field. The observed creep behavior is attributed to time-dependent plastic deformation based on loading rates. There is a lot of work in the field of nanoindentation in order to understand the dynamic effects on nanomechanical properties. The paper aims to discuss these issues.

The deformation mechanism is investigated under two experimental approaches (high and low loading rates, respectively) during nanoindentation. The effect of loading rate in the nanomechanical properties, during nanoindentation creep of zinc layer on hot dip galvanized (HDG) steel, is discussed through nanoindentation.

Analysis of this research effort is emphasized on nanoindentation stress exponent, a critical parameter for the life time and reliability of nano/micro-materials and systems. The corrosion resistance was studied by electrochemical impedance spectroscopy (EIS) and localized EIS.

The study of nanoindentation as a reliable method to extract creep properties as well as for fundamental understanding of deformation mechanisms at small length scales is an open interesting field. The observed creep behavior is attributed to time-dependent plastic deformation based on loading rates. The deformation mechanism is investigated under two experimental approaches (high and low loading rates, respectively) during nanoindentation. The effect of loading rate in the nanomechanical properties, during nanoindentation creep of zinc layer on HDGsteel, is discussed through nanoindentation. Analysis of this research effort is emphasized on nanoindentation stress exponent, a critical parameter for the life time and reliability of nano/micro- materials and systems. The corrosion resistance was studied by EIS and localized EIS.

The purpose of this paper is to perform the evaluation of copper susceptibility to corrosion in industrial cooling systems. Microstructure and defects of copper are observed, while divergences from optimum structure are discussed.

Various types of corrosion are examined. Electrochemical techniques such as electrochemical impedance spectroscopy and potentiodynamic polarisation are applied in these materials, using corrosion inhibitors. Microscopic observations and electrochemical measurements are interpreted according to possible mechanistic scenarios.

It is evident that, under specific conditions (e.g. high pH), water cooling ingredients can enhance corrosion, leading to significant copper mass loss from the inner surface of the pipe and thus leading to failure.

Evaluation of copper corrosion in cooling industrial systems was done, as well as studies of copper corrosion in sodium chloride.

The purpose of this paper is to produce cobalt (Co)-based thin films by metalorganic chemical vapor deposition (CVD) technique and then to evaluate structural and mechanical integrity.

Co-based thin films were produced by metalorganic CVD technique. Boronizing, carburization and nitridation of the produced Co thin films were accomplished through a post-treatment stage of thermal diffusion into as-deposited Co thin films, in order to produce cobalt boride (Co₂B), cobalt carbide and cobalt nitride thin films in the surface layer of Co. The surface topography and the crystal structure of the produced thin films were evaluated through scanning electron microscopy and X-ray diffraction, respectively. The mechanical integrity of the produced thin films was evaluated through nanoindentation technique.

The obtained results indicate that Co₂B thin film exhibits the highest nanomechanical properties (i.e. H and E), while Co thin film has enhanced plasticity. The cobalt oxide thin film exhibits higher resistance to wear in comparison to the cobalt thin film, a fact that is confirmed by the nanoscratch analysis showing lower coefficient of friction for the oxide.

This work is original.

The purpose of this paper is to deal with the study of properties of anticorrosion powder based coatings on aluminium alloy 2024.

The powder based coatings were applied to the AA2024 substrates using a spray coating technique. All the substrates were covered with a primer prior the powder based coatings. The morphology and composition of the coatings was examined by scanning electron microscopy and energy dispersive X-ray analysis, respectively. Studies on the corrosion resistance of these coatings were made using electrochemical impedance spectroscopy.

The results reveal that the powder based coatings together with the primer coatings demonstrate improved corrosion protection to AA2024 after exposure to corrosive environment. Moreover, the primer coating is mechanically enhanced compared to the top coating, while the top coating exhibited significant resistance to wear.

The paper deals with the evaluation of corrosion and nanomechanical properties of coatings applied on aluminium alloy.