The paper presents preliminary research on the application of coatings by the PVD method. The coatings were deposited on an AlNiCo alloy with a suitably pre-prepared surface. Two different coating materials were used. Coatings based on pure silver and pure aluminum were applied. The tests included the assessment of the influence of the coating deposition time on the final thickness of the coatings. The samples after the deposition process were specially prepared for observation under the microscope. Scanning microscopy examinations made it possible to assess the connections of the obtained coatings with the substrate.
Dynamic impact wear, i.e. contact between two components in the presence of high cyclic local loads, is a challenging failure mode that occurs in many mechanical applications. Many previous studies have confirmed that dynamic impact testing is suitable for evaluating the contact fatigue of thermal sprayed coatings. However, the effect of the test parameters on the resulting lifetime is unclear. The aim of this study is to describe the effect of the ball material used in the dynamic impact test on the resulting fatigue life of the HVOF thermal sprayed coating. Two test balls made of 440 C steel and Si3N4 silicon nitride were chosen for this study. Dynamic impaction testing was carried out on the Cr3C2-NiCr coating, which was sprayed by HVOF on a S355J2 carbon steel substrate. The fatigue life of the tested coatings is described in the form of Wohler-like dependence. By means of scanning electron microscopy (SEM), the surface of the impacts as well as the microstructure of the coating on the cross-section in the region of the impacts were observed. Furthermore, the mechanism of crack propagation in the coating was investigated. Electron dispersive X-ray analysis (EDX) was used to determine the distribution of the elements.
The paper presents an idea and preliminary analysis of a new approach to modeling surface geometry by applying advanced computational and analysis of data methods. It assumes that the material's surface may be treated as a random field and can be analyzed using the time series methods. The research aims to develop a model to predict surface geometry textured by a laser beam. Working out predictive models supported by machine learning methods would indicate proper texturing process parameters to obtain specific surface geometry proprieties. The final goal of the research is to develop a model to predict the surface geometry parameters according to texturing process parameters. As a data set for the development and testing of the model, data from the profilometric test of samples with a cermet coating after laser with different beam power will be used.
Diamond-like carbon (DLC) coatings are characterized by unique properties (chemical, protective and tribological properties), thanks to which they are characterized by high hardness, resistance to chemical agents and a low coefficient of friction. These coatings are more and more often used in industrial applications, which is the reason to check their application in the tribological cooperation of pairs in means of road transport. The main purpose of the article is to determine the working parameters of an internal combustion engine turbocharger after applying DLC coatings on the surfaces of its sliding bearing elements. Such an application can be considered both in the production of new turbochargers and in the regeneration of already operated turbochargers. The use of a turbocharger has been known in technology for a long time, however, in means of road transport this part is increasingly used in accordance with the idea of downsizing (in the past mainly for compression ignition engines, and now also for spark ignition engines). Currently, DLC layers are used in industry, but their use in the regeneration of parts in means of car transport is rather small. The article presents the results of testing the turbocharger operating parameters. the tests were carried out using a special test stand. Based on the obtained test results, it can be concluded that the application of the DLC coating on selected surfaces of the turbocharger sliding bearings allows for the change (improvement) of its operating parameters (e.g. increasing the rotational speed of the turbocharger rotor and the air pressure on the compressor side at fixed turbine operating parameters).
Cold spray is a modern method of coating in which solid powder particles are accelerated by a supersonic gas jet and on impact with the substrate they deform plastically and adhere to the surface. This principle of coating formation is dependent on the critical velocity of the flying particles, which is influenced, among other things, by the distance of the coated material from the nozzle end. Therefore, this work investigates the effect of stand-off distance on the microstructure of austenitic stainless steel coatings deposited by cold spray technology. The Cold Spray CS EvoII 6/11 equipment was used in the experiment, using two convergent-divergent nozzles that differ from each other in length and expansion ratio. Different stand-off distances (10 mm, 30 mm, and 50 mm) were used in this work and their effect on the properties of the resulting coatings was observed, such as in particular the quality of the interface between the base material and the deposited coating, porosity, roughness, and coating thickness. The results showed that the stand-off distance of the coating significantly affects the quality and properties of the coating, with the best results obtained for samples deposited at a stand-off distance of 30 mm.
Currently, polymers are a group of future-proof materials, which, in contrast metals, are characterized by low weight and also are easier to obtain and relatively cheap. However, due to their low surface energy, their use is often limited. Due to plasma technology, it is possible to modify the surface properties of polymers in a cost-effective and efficient way. During the last years, low temperature plasma surface functionalization of polymer materials has increasingly earned a high position in a wide range of application fields. This paper present the influence of ion etching technology on modyfication of the surface of different types of polymers. An assessment of the impact of the operating parameters of the ion gun on the surface properties of polymers was presented. An analysis of the surface morphology, chemical composition and physicochemical properties of polymer materials after the activation process was carried out.
This paper presents the results of tribological wear resistance tests on pure chromium subjected to xenon ion implantation with an energy of 160 MeV. Chromium is a very popular engineering material used in many industries, including aerospace, automotive, power generation, and electronics. It owes its popularity to its resistance to high temperatures, corrosion, and high mechanical strength. High-energy heavy ion implantation causes a significant amount of radiation damage, which affects the crystalline structure of the material's surface layer and thus changes its mechanical properties. This is especially important in space and nuclear power applications. The research was aimed at demonstrating changes in frictional wear resistance as a result of exposure to Xe ions at different doses per unit area. The research was conducted using the pin-on-disc method in an aqueous environment. The effect of increasing the dose of implanted ions on the tribological resistance of pure chromium was demonstrated.
This paper deals with the testing of the properties of a bonded joint made of aluminum alloy EN AW 5754, where the laser cleaner MRJ FL C120 was used for the preparation of the bonded surfaces. Different laser beam settings were used to achieve the desired roughness. The bonded joints were formed using a two-component high strength epoxy adhesive. The research analyzes the effect of surface roughness created by MRJ FL C120 laser cleaner on the strength of the bonded joint under tensile test. The adhesion of the adhesive to the surface of the bonded material is analyzed. Furthermore, the tensile strength test results as a function of the surface roughness of the material are evaluated. In the evaluation of the results, the effects of different surface roughness produced by the laser cleaning method on the strength of the bonded joint were determined.
The study reported in this paper was undertaken to assess whether certain ecologically-disastrous surface treatments, such as chemical and electrochemical treatment could be replaced with ozonation. The proposed technology is both ecologically-sound and relatively inexpensive. The research works were conducted on 316L steel substrates and involved photoelectron spectroscopy (XPS). The band positions on the review spectrum provide the basis for the qualitative identification of the atoms forming the surface layer, whereas their intensity - data for the calculation of the total concentration of these atoms in the analysed layer. High resolution spectra are used to determine the type of chemical bonds - based on the characteristic numbers of chemical shift. The results of tests on the state of surface layer energy of 316L steel substrate following ozone treatment are also presented. The conducted tests and the analysis of the obtained results indicate that ozone treatment effectively removes atmospheric carbon contaminants off the specimen surface. The test results show a decrease in atmospheric carbon on samples after ozone treatment compared to untreated samples. Moreover, results show an increase in the value of the free surface energy in specimens subjected to ozone treatment.
Anodization is a technique that can be used to create thin layers of oxide on the surface. Thin oxide layers have been found to be useful in a variety of applications, including emitters of electrons.
Tungsten is still often choice for cold field emitters in commercial microscopy applications. His suitable quality can be improved even more by deposition of thin layer. Not only emission characteristic can be improved, but also emitter operating time can be prolonged. Tungsten oxide is known for its excellent resistance to corrosion and chemical attack, which is due to its stable crystal structure and the strong chemical bonds between tungsten and oxygen atoms. Many techniques were for this purpose applied, with various advantages and disadvantages. For this work anodization were chosen, because of controllable uniform material coverage and easy accessibility without the need for expensive complex equipment. For this purpose, a simple apparatus was built, and a custom software was used.
The anodization process involves applying an electrical potential to the tungsten while it is immersed in an electrolyte solution. This causes a thin layer of tungsten oxide to form on the surface of the metal. The thickness and properties of the resulting oxide layer can be controlled by adjusting the anodization conditions such as the electrolyte solution, the voltage, and the duration of the process. In this work, H3PO4 was used, and voltage were changing.
To test, if this tungsten oxide layers would be adjustments for electron emission properties, making them ideal for use in electron guns and other devices that require high-quality electron emitters, we put them through a series of tests and properties were evaluated using appropriate techniques.
Overall, anodization of tungsten to create thin tungsten oxide layers is a promising technique to produce high-quality electron emitters.
Vitreous enamel coatings play a very important role in the coating production process of steel in accordance with the technical and aesthetic properties. Surface quality of the enamel coating can be affected by various defects. In this study, some examples of case of defects, mainly the loss of adhesion are presented on different type of products. The reasons of the adhesion lost are different according to usage of products.
The main objective is to design and analyse laser cladding with different additive materials and variable cladding parameters. Claddings were made to increase the corrosion and mechanical resistance of highly stressed rotating parts. Metallographic analysis of clads was carried out using optical microscopy, surface hardness measurements and hardness profiles. Detailed microstructural analysis using Electron Backscatter Diffraction (EBSD) was carried out on selected clads. Clads were subjected to wear testing.
The article presents the results of tests concerning the metal-mineral abrasive wear resistance of arc-sprayed and HVOF-sprayed coatings as well as overlay welds made using self-shielded flux-cored wire (classification of Fe15 in accordance with EN 14700). The significance of the above-named effect was determined using a completely randomized design. The scope of tests also included the analysis of the chemical and phase compositions, hardness measurements as well as the macro and microscopic metallographic tests of the deposited coatings and layers.
Crude glycerol is a by-product of biodiesel production. In the present work, it has been evaluated as a potential inhibitor of steel corrosion in aqueous media. The corrosion resistance of low alloy structural steel S355MC in non-purified crude glycerol was studied by electrochemical methods. The results have been compared with tap water. An open circuit potential (OCP) of the steel in crude glycerol was more negative compared to that of tap water. The OCP was stable over time, indicating a rapid formation of passive layer on the steel substrate. The corrosion behavior was further explored by electrode polarization. On the polarization curve of steel in crude glycerol, a wide passivation region was observed. The corrosion rate was 2.2-times lower compared to tap water. The surface of steel exposed to crude glycerol was covered with an adherent layer of corrosion products. The surface of steel exposed to tap water, on the other hand, was significantly affected by red rust. These results indicate a significant corrosion inhibiting activity of crude glycerol.
ACKNOWLEDGEMENTS: This work was funded by the Slovak Research and Development Agency (project no. APVV-20-0124), the Scientific Grant Agency of the Ministry of Education, Science, Research and Sports of the Slovak Republic and the Slovak Academy of Sciences VEGA (project no. 1/0692/22) and European Regional Development Fund (project no. ITMS2014+: 313011W085).
Applying protective coatings to machine parts can be economically justified in cases where the wear is localized, or when the coating material is expected to display properties that differ from those of the substrate. Technological surface layers (TSLs) are typically applied to objects before use, whereas functional surface layers (FSLs) are applied during maintenance. Laser surface modification is a field of study that involves numerous research centers worldwide. By controlling laser parameters such as power, scanning speed, and pulse duration, it is possible to create coatings with various surface properties, such as surface geometry, microhardness, stress states, or resistance to wear. One of the most common and affordable techniques for surface modification is electro-spark alloying (ESA) or electro-spark deposition (ESD), which involves using a focused stream of energy similar to laser treatment. However, electro-spark deposited coatings may have drawbacks that limit their application. To address this, the coatings can be further treated with a laser, which effectively eliminates surface defects such as scratches, delamination, and microcracks. Additionally, the laser treatment seals the coating, improving its overall performance. ESA coatings have multiple applications, including protecting new elements and restoring the properties of worn elements. ESD is a proven technique for regenerating aircraft engine and hydraulic components in specialized vehicles. The production of ESD protective coatings has also found extensive use in the automotive industry. Significant research has been conducted to assess the effect of various ESD parameters on the properties of coatings. This paper aims to determine the properties of electro-spark coatings by analyzing their microstructure, measuring their microhardness, friction force, and corrosion resistance. To carry out these tests, a Cu-Mo coating (the anode) was electro-spark deposited onto carbon steel C45 (the cathode). The resulting coatings are intended for use in increasing wear and corrosion resistance.
It is well-known nowadays, that the resistance of the material to brittle cracking is a very important parameter for the characterization of PVD coatings, which can be analyzed in cyclically changing loads. The fracture toughness of solid materials is determined by the critical value of the stress concentration coefficient KIc [1,2]. The nanoindentation method can be used to assess the fracture toughness of various PVD coatings. The authors showed in their previous research that it is possible to determine the KIc of PVD coatings by Niihara [3] and Laugier model [4, 5].
For smooth coatings with good roughness, the best method of investigation can be the nanoindentation method with the Berkovich indenter and Laugier model [6]. The authors made an attempt to investigate the fracture toughness of coatings based on metal oxide by using the nanoindentation method. An important observation is that it is possible to use the nanoindentation methods for the mechanical characterization of the micro-volume systems. REFERENCES: [1] Standard: PN-87/H-4335.; [2] Zhu X.-K. et al., Engineering Fracture Mechanics 85 (2012)1-46.; [3] Niihara K. et al., Journal of Materials Science Letters 2 (1983) 221-223.; [4] Laugiera M.T. et al., Journals in Materials Science Letters 6(1987) 355-356.; [5] Sowa S. et. al., Conference paper METAL 2022 19(2022)555-560.; [6] Smolik J. et al., Materials MDPI 15/24 (2022) 9061.
Paper investigates the cavitation erosion (CE) of WC-Co-Cr coatings deposited by different methods, i.e. HVOF, HVOAF and stainless steel and brass. Coatings were deposited using the WC-Co-Cr feedstock powder onto steel substrates. Microstructure, porosity, hardness and phase composition were investigated. Cavitation erosion testing was done using ASTM G32 standard with stationary sample method and using AISI 304 steel as a reference sample. Cavitation erosion curves and erosion mechanisms were comparatively analyzed. The cavitation erosion resistance of coatings is higher than those reported for reference metal alloys. The cavitation erosion wear mechanisms of coatings and metal alloys were observed using SEM-EDS. Differences relating to coatings time-erosion behavior were analyzed in relation to the reference alloys. Finally, original CE models of WC-Co-Cr cermet’s combine the microstructural properties of the coatings. This paper gives a remark for designing the thermal spray coating microstructure for anti-cavitation performance.
Magnesium and its alloys are attractive materials but have the disadvantage of high reactivity and low corrosion resistance. For this reason, surface treatments comprising coatings such as doubly layered hydroxides (LDH) are prepared. In this work, Al-Mg LDH coatings on AZ31 magnesium alloy were prepared at different temperatures (up to 90 °C) and different reaction times. Optimal reaction conditions were chosen, which included a temperature of 90 °C and a time of 6 h. Surface morphology and elemental composition of coatings were characterized by a scanning electron microscope (SEM) with an energy dispersive X-ray spectroscope (EDS). The presence of LDH coatings and phase composition were analysed by X-ray diffraction (XRD). Potentiodynamic polarization (PDP) measurements in 0.15 M NaCl were used to evaluate the corrosion properties of the prepared LDH coatings.
Magnesium materials are desirable to be surface treated because of their low corrosion resistance. In our work, we focused on the use of plasma electrolytic oxidation (PEO) coatings and humic acid (HA). HA is a heterogeneous mixture of organic molecules that occur naturally in nature. PEO coatings were prepared on the surface of AZ31 magnesium alloy using a bath containing Na3PO4, KOH and various amounts of humic acid. The coatings were characterized using a scanning electron microscope (SEM) with an energy dispersive X-ray spectroscope (EDS), Fourier-transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The corrosion properties were tested using the potentiodynamic polarization method in 0.15 M NaCl. The results indicate that good corrosion resistance of AZ31 alloy was obtained in the presence of 25 mg/L HA and lower concentrations of HA. The optimum deposition time for the preparation of the coatings was 10 or 15 min.
This article deals with the evaluation of the microstructure and tribological and mechanical properties of hardmetal coatings based on WC and CrC, which were applied to the base material W. Nr. 1.0570 by the HVOF thermal spraying technology. Experiments such as microhardness HV0.3, surface hardness HR15N, adhesion determination ASTM C633-79, abrasive wear ASTM G65 and ASTM G133-22 reciprocating sliding wear test were performed to compare the properties of the coatings and see how they differ depending on the selected additive material. Most of the tested coatings generally had high hardnesses, high wear resistance and reduced coefficient of friction, but were not significantly different. The only exception was the coating with the chemical composition 70(WC/Cr3C2)-21Ni9Cu, where the properties were significantly worse.
The quality of the surface of products and structures is one of the current requirements of industrial production and trade. The treatment of the surface of products and structures, which is intentionally created by human activity, protects their surface from corrosion, adjusts their appearance / color shades /, improves their surface properties in terms of mechanical properties / hardness, abrasion resistance, etc. /, protects against corrosion with the aim of increasing their lifespan. Surface engineering essentially combines functionality, decorativeness and symbolism of individual products and structures.
The future of the development of modern trends in surface engineering lies not only in the technologies of applying protective coatings, but especially in the educational process, in which the human individual is gradually introduced to this issue. The study of teaching for primary and secondary schools can subsequently contribute, through the person of the teacher, to the awareness of pupils and students in this area and thus support the interest of the young generation in studying at colleges and universities that have accredited subjects in the field of surface engineering in their study program.
The paper presents the experience and results of the study of new teachers at the Department of Technical and Vacational Education of the Faculty of Education of the University of Ostrava in technical subjects, which also includes the teaching of surface engineering.
It has been observed that the products obtained by means of 3D printing technology, even in the case of consideration of optimal parameters of printing technology recommended by the manufacturers of metal powders laser sintering systems, are characterized by certain structural
discontinuities (defects for example: pores and unmelted powder) in surface layer. Therefore, surface modification via shot peening is considered suitable for additive manufacturing of parts made of 17-4PH stainless steel. The specimens have been produced by means of EOSINT M280 system dedicated for laser sintering of metal powders. The objective of this study was to determine the effect of shot peening pressures (0.4 MPa and 0.6 MPa) and two types of blasting media (CrNi steel shot and ceramic beads based on ZrO2) on the tribological characteristics, surface topography and hardness of specimens of DMLS 17-4PH stainless steel. Wear tests have been carried out by means of ball-on-disc tribotester in dry sliding method at room temperature (about 22ºC). Wear loss after tribology testing was calculated via profilometry measurements of the worn surface, i.e. wear grooves, using contact profilometer. Finally, the wear mechanism was investigated using a scanning electron microscope. Adhesive and abrasive wear were two predominant mechanisms of tribological deterioration. The general results of all tests indicate to favourable effect of shot peening process on the hardness and wear resistance of 17-4PH steel. The highest increase in hardness was obtained for the surfaces modified by steel shot and ceramic beads using a peening pressure of 0.6 MPa, respectively mean: 550±34 HV0.3 and 554±22.2 HV0.3. DMLS 17-4PH specimens modified by shot peening using steel beads and a pressure of 0.6 MPa exhibited the optimum surface morphology, hardness and microstructure, and thus improved wear.