Seznam abstraktů 2025: POSTEROVÁ SEKCE D

Fluoride conversion coatings are perspective surface treatments for reducing corrosion rate of magnesium and its alloys. This work focuses on the preparation of fluoride conversion coating on magnesium material prepared by powder metallurgy. The base material was prepared by compacting powder magnesium into cylinders 20 mm in diameter and 5 mm thick using 400 MPa of uniaxial pressure. The green compacts were sintered in argon atmosphere at 600 °C for 12h. The coating was prepared by dipping the magnesium materials in molten Na[BF4] salt at 430 °C, the preparation times were 1, 2, 4 and 8 h. The effect of fluoride coating preparation time on thickness and structure of the coating was investigated by mainly two methods. Corrosion resistance was measured by potentiodynamic polarisation in NaCl solution, the structure and thickness of the coating was measured by SEM-EDS (Scanning electron Microscope - Energy Dispersive Spectroscopy) method. The corrosion current decreased significantly with increasing preparation time of the coating. This finding is in correlation with SEM-EDS observation, which confirmed thicker coating layer with increasing preparation time. The structure of the coating was not uniform; however, the coating was formed predominantly on the surface of the individual powder particles from which the base material was formed.

Rolling Contact Fatigue (RCF) is a critical issue that degrades rail surfaces, leading to structural damage and reducing service life. Effective repair techniques, such as plasma cladding with powder filler metal, can restore rail integrity and enhance performance. This study investigates the influence of cladding direction on the microstructure and mechanical properties of Hadfield gradient layers deposited on R260 rails. The research focuses on how deposition orientation affects hardness, phase transformations, and microstructural evolution, particularly the formation of martensitic layers and carbide precipitation within the heat-affected and repaired zones. Optical and electron microscopy are employed for microstructural analysis, while spherical indentation and Vickers hardness testing assess mechanical performance. The study reveals that cladding direction significantly influences carbide distribution, martensitic transformation, and hardness gradients, ultimately impacting fatigue resistance and durability. A deeper understanding of these variations provides valuable insights into optimizing cladding strategies for improved rail repair outcomes. The findings contribute to the development of advanced repair methodologies, ensuring prolonged rail service life and enhanced resistance to fatigue-induced failures. Additionally, the study examines the effect of the number of welding layers and movement patterns of the welding torch in cladding to eliminate the need for post-weld heat treatment. This research serves as a foundation for refining welding parameters and deposition techniques to achieve superior mechanical performance in repaired railway components, ultimately leading to safer and more reliable railway infrastructure.

The article presents research findings on the microstructural studies of TBC coatings deposited on molybdenum, featuring a bond-coat made of molybdenum silicide. Ceramic coatings within the TBC system were produced through plasma spraying in air. Conventional 8YSZ and rare earth zirconate powders (specifically lanthanum and neodymium zirconates) were utilised to achieve this. The ceramic layer's thickness measured approximately 250 µm. The interlayer consisted of a MoSi2 diffusion coating, formed by the diffusion process during the siliconizing of the molybdenum substrate. Ideally, the thickness of this zone should be around 100 µm. The research scope included a visual characterisation of the TBC system to assess its overall integrity. In the second phase of the research, topographic parameters of the surface were evaluated, mainly focusing on the roughness of individual elements within the system. The subsequent assessment highlighted the phase composition of these individual system elements.
During the cross-sectional tests, the ceramic layer was evaluated regarding the architecture of cracks and pores. Quantitative and qualitative assessments were conducted, categorising the pores as spherical, horizontal, and vertical. The final aspect of the cross-section evaluation was the bond quality between the ceramic layer and the silicide bond-coat.

One of the most perspective directions of the surface engineering development in recent years concerns the possibility of producing coatings with bactericidal properties. For this purpose modern plasma technologies are used. Due to the very large possibilities in shaping the chemical composition of coatings, their microstructure and thickness, as well as the large variety of their deposition methods, they will enable the production of coatings with various functional properties.
The article presents the possibilities of using the High Power Impulse Magnetron Sputtering HiPIMS technology to deposit composite coatings with biocidal properties. In the article, in addition to the results of the bactericidal properties, the authors also presented an analysis of the material properties (microstructure, phase composition) and physicochemical properties (wettability) of the tested coatings. The presented results confirmed the very good biocidal properties of the ZnO+Cu coating against various groups of microorganisms (bacteria and fungi) simultaneously.

This article focuses on the effect of curing temperature on the strength of adhesive joints used in vehicle prototypes. Testing the influence of curing temperature on the adhesive joint was carried out on samples of aluminum alloy EN AW 5754, with the adhesive surface prepared by abrasive blasting. Samples of aluminum alloy were bonded using three types of two-component adhesives. Two types of adhesive joints are addressed here. Firstly, adhesive joints cured at +20 °C for 168 hours, and secondly adhesive joints cured at +80 °C for 1 hour. The samples are tested using a tensile test, and the resulting data is plotted in graphs in the experimental section and compared. The achieved results of the experimental activity are discussed in the conclusion.

This work examines the properties of bonded joints used in prototype vehicles with an emphasis on factors that affect joint strength and service life. Selected materials, including EN AW 5754 aluminum plates, S235 structural steel and carbon composites, are bonded with various adhesives after surface preparation by sandblasting and cleaning. The study examines the durability of these joints and compares them to assess their durability and effectiveness in automotive applications. The practical part describes the experiment from the selection of materials, the preparation of surfaces for gluing and the selection of glue. This is followed by the implementation of the experimental part, which includes the gluing process itself and testing the resistance of the joint using a tear test. In the final section, an evaluation of the measurement results, to which a final summary was completed, is carried out.

Deposition of layered double hydroxides (LDH) on metal surfaces, especially Mg alloys, is considered a promising approach for protective conversion surface treatments. For Mg materials, the formation of LDH coatings on the surface is carried out in an autoclave at elevated temperature or in solution. MgFe-based LDH coatings may find application in medicine. However, their issues are poorly described. In this paper, the growth of MgFe LDH conversion coatings on AZ31 magnesium alloy is described. In this study, MgFe-LDH coatings were prepared on hydrothermally treated AZ31 Mg alloy. The morphology was characterized by scanning electron microscopy (SEM). The chemical and phase composition was determined by X-ray diffractometry (XRD) and energy dispersive X-ray spectroscopy (EDS). Two-step synthesis at laboratory temperature was performed. First, a FeOOH layer with a thickness of about 2 µm was prepared at room temperature. While at higher temperature (60 °C), a Fe3O4 layer with a thickness of about 0.7 µm is formed. These FeOOH and Fe3O4 layers are transformed to form MgFe-LDH in the second step when reacted in 0.1 M magnesium nitrate for 12 and 24 h. The thickness of the resulting MgFe LDH layer ranged from 0.5 to 1.5 µm. The results suggest that this synthesis method leads to the synthesis of non-traditional LDH coatings that can improve the corrosion and bioapplication behavior of Mg materials.

DLC (Diamond-Like Carbon) coatings have found applications in various industries due to their unique mechanical properties and wear resistance, which are closely related to their structure. These coatings exhibit a high ratio of sp³ to sp² bonds among carbon atoms. In the present work, DLC coatings were deposited by High Power Impulse Magnetron Sputtering method using several different substrate polarisation values with different Ubias in the range: -25 V, -50 V, -75 V, -100 V, -125 V. As the substrates 316L steel with a Cr-CrN coating, aimed at enhancing both the adhesion of the DLC coating and its mechanical properties, was used. In order to analyse the phase composition of DLC coatings, the Raman spectroscopy method was used. Mechanical properties were investigated by the nanoindentation method by using nanohardness tester from Anton Paar with Berkowich diamond indenter. The results of tests showed that DLC coating deposited with substrate polarisation -50 V had the biggest content of sp3 bonds and the best mechanical properties.

The glass microfiber filters (GF/A) are designed to monitor water and air pollution, wastewater filtration, algae and bacteria culture filtration, protein filtration, and food analysis. Filters are characterized by low flow resistance and allow for a high workload. Thin films of CuAg, Cu, Ti, Zr, CuxAgyO, CuxO, TiOx and ZrOx were deposited on the surface of glass fiber filters using DC magnetron sputtering (PVD). The study indicated that CuxAgyO and CuxO films exhibited thicknesses similar to those created by non-reactive deposition. In contrast, TiOx and ZrOx films required three times longer deposition durations to achieve similar thicknesses to pure metal films. The research explores modification of the surface of glass fiber filters using CuAg, Cu, Ti, Zr, CuxAgyO, CuxO, TiOx and ZrOx thin films deposited by DC magnetron sputtering (PVD). Thin films containing oxygen demonstrated improved tribological properties with reduced static and dynamic friction coefficients.

The study investigated the influence of electrolyte composition on the structure, phase composition, corrosion resistance, and tribological properties of structural steels 40Kh and 20Kh2N4A during cathodic electrolytic plasma saturation with nitrogen and carbon. The processing was conducted using an electrolyte composed of 10% sodium carbonate (as an electrical conductor), 20% carbamide (as a source of nitrogen and carbon), and 70% distilled water. To enhance surface carbon saturation, 5% glycerol was added to the second electrolyte. Samples were processed under a two-step regime. Initially, a high voltage of 320 V was applied for 10 seconds to ignite and stabilize the plasma, followed by a rapid decrease to 180 V, maintained for 3 minutes. The investigations revealed that after diffusion saturation with nitrogen and carbon, the surface of the samples exhibited nitride and carbide phases (Fe₃C, Fe₃N, FeC), as well as iron oxide phases (Fe₂O₃ and FeO). Cross-sectional analysis of the samples showed that the structure of the samples without glycerol consisted of an oxide layer, a nitride zone, and a carbide zone. In contrast, with the addition of glycerol, a nitride-carbide zone followed the oxide layer on the surface. The microhardness of 20Kh2N4A structural steel in these zones reached 900 HV, while the microhardness of 40Kh steel was 450-500 HV. The wear resistance of the samples processed in the electrolyte containing 5% glycerol increased by 2-2.5 times. However, corrosion resistance studies indicated that the addition of glycerol to the electrolyte negatively affected the corrosion performance of the steels.

The evolution of paint coatings is quite rapid, multidirectional and most interesting . The progress in the field of polymer coating technology stems from the three most important functions, i.e. the decorative function, the protective function and the informative function. Paint systems account for approximately 50% of all coating systems. It is estimated that about 95% of steel structures are safeguarded against corrosion with protective coatings, including as much as 90%  with paint coatings. The service life of paint systems ranges from several months to several years.
A special group of paint systems are paint coatings for military applications, mainly for camouflaging weapon systems and military equipment. Paint coatings are fundamentals of camouflage - they camouflage vehicles/objects in the optical range, both in visible light (VIS) and in the near-infrared (NIR) range. The main task of effective camouflage is to eliminate those features, which may cause the object to be differentiated from its surroundings, i.e. those that make it possible to distinguish one's own assets from the background, and these may include, for example, colour, shape, size, gloss and texture.
The paper presents an analysis of the functional operational properties of two-layer coatings for use in military technology. The properties were evaluated based on microstructure analysis and measurements of surface geometric structure, hardness and adhesion. The tests were carried out for two-layer masking coating systems made in three variants: coating system (SP1), coating system modified with carbon nanotubes (SP2), coating system modified with glass microspheres (SP3). Paint coating systems were applied by pneumatic spraying to DC01 steel samples using SATA guns. Due to their operational properties, the developed coating systems can be used on weapons and military vehicles.

The report presents the correlation between roughness and vibration in friction stir welding. The transverse acceleration of the welded plates during welding was measured. The velocity and displacement in the transverse direction were determined by numerical integration. The welded joint was scanned and the profile in the joint area of the parts was obtained. The displacement results were compared with the roughness results. An analysis of the deviations in the two results was performed.

Among the advanced reactor designs of the fourth generation of nuclear reactors, the Lead-cooled Fast Reactor (LFR) stands out as one of six distinct types. The corrosion damage of the steels, it is caused by liquid metal acting on the structural material, which is considered a significant obstacle in the development of the fast reactors concept. The corrosion resistance and chemical compatibility with environment of 9Cr-1Mo, ferritic alloy steel (T91), in condition of the static liquid lead with 10-6 wt.% oxygen at 520 ºC are analysed in this study. The specimens were exposed for 3500 hours. The specimens tested were the reference T91 and T91 with the coating on base Al and Ti was applied to the second specimen. The coating applied by physical vapor deposition were used for corrosion resistance improvement. The formed oxide scale of reference T91 consists of an outer layer with a Fe-Cr spinel structure and an inner internal oxidation zone (IOZ). Corrosion damage was characterized using electron microscopy techniques, which identified networks of solution-based attack (SBA) intrusion beneath liquid lead wetted surfaces. The damage to the coating depends on their chemical composition and structure of the coating. However, in general, the application of the coating increased the resistance of the surface to corrosion damage.

The effectiveness of the protection of the base metal by the popular corrosion inhibitor BTA (1,2,3-benzotriazole) depending on the method of application of the inhibitor was verified on lead coupons in an environment contaminated with acetic acid. The BTA inhibitor was applied alone or in combination with a protective wax and/or varnish coating: a multi-layer system (BTA-single-layer wax/varnish, BTA-double-layer wax+varnish) or a BTA additive to the wax/varnish coating. As part of a long-term experiment (almost 2 years), the effect of the length of immersion of the metal in the BTA solution and the effect of aging of the protective coating on its anti-corrosion effectiveness and visual changes of the base metal were monitored.

Polymer surface treatments are now a commonly used technology that finds application across many industries. The paper discusses the results of experimental tests of mutual adhesion of samples of basic polymeric base materials such as PLA - polylactic acid, PETG - polyethylene terephthalate glycol and ASA - acrylonitrile styrene acrylate as base materials produced by FDM 3D printing with two-component coating system LV AKZ 421 /manufacturer Synpo a.s./. The adhesion of the designed coating system as a surface protection of the above polymeric materials was tested according to the valid ČSN EN ISO standards for adhesion determination. Based on the results of the experimental tests, it was found that the best suited to the proposed coating system is the PLA substrate material