Seznam abstraktů 2018: SEKCE D - MODERNÍ TRENDY V POVRCHOVÉM INŽENÝRSTVÍ

There are various solutions to the endings of chimney, flue and ventilation ducts. Their location is largely high-altitude installations and quite often difficult to access. The study presents the results of expert tests for diffusers - exhaust gas regulators; new and after long-term use. The tests included a structural and organoleptic assessment of the diffuser plate surface. Changes of sheet metal geometry and thickness as well as corrosion resistance in the context of behavioral character under the influence of temperature of exhaust gases and changing atmospheric conditions. For these reasons, appropriate tests were carried out to check the quality in the context of long-term chimney exploitation.

Infrared nondestructive testing (IRNDT) is an active thermography method for inspection of material-surface inhomogeneities or discontinuities. It is based on an excitation of an inspected sample and a detection of its thermal response by thermographic methods. The IRNDT is commonly used for an inspection of delaminations. However, it is also applicable for surface and subsurface cracks detection, which is the focus of this contribution. Principles of IRNDT methods are introduced in this contribution. Flash-illumination, ultrasonic-loading, laser-heating and mechanical-loading excitation methods, which are mostly used for cracks detection, are described. Examples of results of an IRNDT inspection of cracks by different approaches are presented.

Infrared nondestructive testing is an inspection method based on an external excitation of a measured sample and a thermographic analysis of its thermal response. It often uses advanced evaluation techniques based on temperature spatial and temporal changes. IRNDT is a suitable method for an inspection of thin samples, near-surface layers and cracks. Usability of IRNDT evaluation is demonstrated on crack detection on mechanically cyclically loaded welded pipes in this contribution. The goal of the analysis was to detect location of crack before this crack is created and visually detectable. Results showed that a thermographic record without an advanced IRNDT evaluation could detect crack just before the mechanically loaded pipe is starting to break down. The IRNDT evaluation detected a position, where the crack appeared later, since the loading had started. The experiment, the evaluation method and the results are described and the IRNDT evaluation advantages and disadvantages are discussed in this contribution.

The paper is devoted by evaluation of comparison of selected systems of thin film – basic material, which are optimized in the range of solution of the project with goal application of thin films on selected real cutting tools. There are evaluated thin films prepared by low voltage reactive arc evaporation in vacuum with different composition of ternary nitride. The evaluation of properties and behaviour is oriented on systems with thin films TiSiN, AlCrN and AlTiN. The surfaces of these systems of thin film – basic material are evaluated from point of view of verification homogeneity of thin films through of area of samples and through of geometry of selected real tools too. The distribution of thickness is evaluated by x-ray fluorescence analysis on samples and real selected places of geometry of tools too. The other comparison is realised from point of view of differences of mechanical properties and behaviour by using of indentation methods namely of nanoindentation and scratch indentation for evaluation of differences in hardness and adhesive cohesive behaviour of systems thin films – basic material.

The main subjects of this presentation are layers made of alumina obtained from organic and aqueous sols deposited on the steel substrates by the sol-gel and electrophoretic deposition (EPD) methods.
Aluminum oxide has a very large specific surface area. As a result of the calcination process, in the burned aluminum layer acid-base active centers are created. It determines the use of aluminum oxide as a catalytic material. Due to its properties it is prospective as a carrier of catalysts.
In the case of the sol-gel method, the sol was obtained by hydrolysis of the butoxy derivative of aluminum. Obtained sol was applied to the steel substrate by a dip-coating technique. Using the dip-coating technique, due to the ability to easily regulate the speed of immersion and ascent of the substrate from the sol, allows relatively easy control of the thickness of the obtained layers [2,3].
In the case of EPD method, stable aqueous colloidal suspension of alumina was used. The main advantage of the EPD method is the ability to easily and quickly obtain homogeneous layers on conductive substrates (also on the profiled surfaces). The thickness of the layers can be easily controlled by changing the process conditions [4].
Fresh layers obtained by both method were heated for densification and better adhesion to the substrate [5]. The structure (MIR, Raman) and microstructure (SEM with EDS) tests carried out showed that in both cases there were obtained tight layers of aluminum oxide on steel substrates. In order to determine the nature of the surface, the contact angle and surface free energy tests were also performed.
The conducted research allowed to state that the coatings obtained by electrodeposition are characterized by better homogeneity and adhesion to the substrate. They also present a higher thickness than the sol-gel coatings. The contact angle tests show that both coatings are hydrophilic.The obtained layers are extremely promising materials due to their physicochemical and surface properties.
REFERENCES: [1] J.Ogonowski, E.Sikorska, D.Walska, Wpływ temperatury aktywacji i czasu pracy katalizatora y-Al2O3 na jego aktywność w reakcji konwersji alkoholi metylowego i izobutylowego w etery (1999);[2] H. Schmidt, J. Non. Cryst. Solids 100 (1998) 51.; [3] P. Colomban, Ceramics International 15 (1989) 23; [4] A. Stoch, E. Dlugoń, W. Jastrzębski, J. Stoch, Ceramics Bulletin 66 (2001) 1007; [5] A. Stoch, E. Dlugoń, J. Stoch, B. Trybalska, M. Bursa, Metallurgy and Foundry Engineering 23 (1997) 221.

The article presents the results of the milling tests - "hard machining" - on the processed (hardened and tempered) material X37CrMoV5-1 (ČSN 19552). At the beginning, the hardness tests of the machined material block were carried out using the Rockwell method. Machining tests were focused on the evaluation of hard machining efficiency and were performed under comparable conditions. At the first stage thin films TiSiN and AlCrN were optimized as a part of a project solution for machining highly and medium hardened materials. Original coating TiAlN was also used for comparison in the second stage. As a result, the flank wear documentation of thin films TiSiN, AlCrN and TiAlN was processed with the same tooling time being set. The flank wear VB and the effectiveness of using the coatings from other perspectives were also evaluated.

Inhibition of stainless and mild steel corrosion in 1 M HCl solution by 1-octyl-3-methylimidazolium bromide and 1-dodecyl-3-methylimidazolium bromide was investigated using electrochemical and weight loss methods. The qualitative surface analysis was carried out. The studied compounds showed appreciable inhibition efficiencies. Polarization measurements proved that they are mixed-type inhibitors with predominantly anodic action. The inhibition efficiency for mild steel is higher comparing with AISI 304 stainless steel. The Gibbs energy of adsorption was calculated by means of the Langmuir isotherm.

In this work, modelling of Nitinol (Ni-45 wt.%Ti) coating deposition, by means of High Velocity Oxygen-Fuel (HVOF) technology, is presented. Species transport model and k- ε turbulence model were solved in Ansys Fluent environment, in which combustion between Kerosene and Oxygen, gas and Nitinol particle flow in a GTV HVOF-K2 gun (GTV Verschleiss-Schutz GmbH, Germany) were simulated. The effect of spraying process parameters, such as spray distance, particle shape factor, and Kerosene to Oxygen feed rate ratio, affecting coating properties and quality, on the supersonic gas flow dynamics, particle velocity and temperature, was numerically investigated. Moreover, correlation between modelling findings and coating quality was explored. Numerical findings highlighted that the higher the Kerosene to Oxygen feed rate ratio the higher the temperatures and velocities of both gas and particles and the combustion pressure; moreover, with particle shape factor lower than 1, velocity of particles increased while ultimate temperature decreased. Furthermore, the findings of this study allowed to predict the properties of impacting Nitinol particles on substrates and showed the thermal story of the particle from the injection to the impact. These above-mentioned aspects are of great importance because Nitinol is a Shape Memory Alloy and its performances strongly depend on stress and thermal state.
ACKNOWLEDGEMENT: This manuscript has been financially supported under “Horizon 2020 – The Framework Programme for Research and Innovation (2014-2020): Future and Emerging Technologies (FET Open)", project title: "An Innovative Method for Improving the Structural Integrity using SMA Revolutionary Technology (InnoSMART)” - Grant Agreement No 664892.

Abradable seal coatings are used to increase the efficiency of aircraft or industrial turbines through decrease the necessary clearance between the rotating blade tips and the casing. To fulfill the expectations, the coatings have to provide specific properties: high abradability combined with erosion and oxidation resistance. In order to achieve the combination of such contradictory material properties, a specific microstructure was developed, consisting of usually metal matrix responsible for erosion and oxidation resistance and solid lubricant phase, responsible for abradability. To deposit such coatings, the atmospheric plasma spraying (APS) technology is the most frequently used, although by easy-to-operate flame spraying (FS) technology the can also provide the abradable seal coatings in good quality. Although the abradable coatings are used extensively in aircraft engines and turbomachinery, the methods of their laboratory testing are still rather limited. In this work, the available laboratory tests methods are exploited to evaluate the mechanical properties of flame sprayed NiCrAl-21%Bentonite abradable coating in the as-sprayed and heat treated state. The possibility of application of the NiCrAl-21%Bentonite coating on the parts with service temperature up to 700°C was verified. Simultaneously, the potential of easy laboratory scratch test for testing of coatings abradability was also investigated.

This paper addresses structural changes of Al-Si coating depending on various heat treatment parameters. Al-Si coated martensitic steel is one of the most commonly used materials in automotive industry for structural parts. Describing transformation of Al-Si coating is necessary in order to understand the phenomena affecting the welding and adhesive bonding stability. Three various heat treatment cycles were used in order to prepare specimens which were later evaluated by scanning electron microscopy, X-ray diffraction and tensile testing. Changes of the phase composition of the coating and mechanical properties of the base material are discussed in the paper.

Nanoindentation methods used for evaluation surface layers are static indentation and scratch indentation too. Static indentation methods are used namely for evaluation hardness characteristics and for evaluation elastic deformation and plastic deformation of surface layers too based on measurement indentation curves – dependence depth indentation and normal force during all indentation process during loading and unloading. Cyclic and step by step indentation modes give possibilities to evaluate much more information about resistivity of surface layers to the indentation stress. Scratch indentation methods are used for evaluation namely adhesive cohesive properties and behaviour of surface layers with very small thickness or/and thin films with very low resistivity of thin films and low hardness. The surface layering is created by technology process of creation of thin films and surface treatment process or by initiation and evolution of degradation process and ageing process. The initiation of degradation and ageing are evaluated in the starting stadium and in the next with step by step sensitive analysis of changing properties and behaviour. From this point of view static nanoindentation and scratch nanoindentation are very useful for analysis step by step changing of mechanical properties and behaviour with high sensitivity and depth resolution too. The paper presented utilization of nanoindentation static and scratch nanoindentation too for very different application in surface treatment but for evaluation of degradation and ageing process too.

Cost saving and continuous improvement of quality in manufacturing of machine parts result in the search for alternative materials for high temperature applications. The recent study presents a comparison of cobalt-matrix material and iron based material for PTA hardfacing. These materials are used for plasma hardfacing of sealing surfaces of industrial valves operating at elevated temperatures. The feed stock powders were compared in terms of particle geometry and quality. The deposits were made by continuous current and by pulse current at 3 and 100 Hz. The samples were subjected to thermal stress at 600 °C for 3 hours. The geometry and the structure of deposits were compared. Microhardness was measured on cross sections of the deposits. It was proved that the iron based material becomes harder after the heat treatment. Even if it shows lower hardness than cobalt based one.

Thin films produced from pure iron and its alloys are commonly used in various fields taking advantage of the magnetic property, hardness or oxygen evolution electrocatalytic property of the layers among many others. However, it can be still challenging to produce layers with low internal stress and uniform thickness. Pure iron itself suffers environmental corrosion because of its high affinity towards chalcogens. Deposition of iron phosphorous (Fe-P) improves the corrosion resistance of the thin films [1, 2]. The structure, physical and chemical property of iron phosphorous layers depends strongly on the phosphorous content of the film. It is well known that amorphous thin films can be produced from 15-20 wt% phosphorous content.
In this work we will present an electrolyte bath for the deposition of iron phosphorous layers having two new environmental friendly additives Poly(2-ethyl-2-oxazoline) (PEOX) (Mw=50,000 g/mol) and Polyethylene glycol (PEG) (Mw=10,000 g/mol). It will be presented how these new additives improve the stability and throwing power of the bath and contribution to improve the corrosion property of the thin films. The electrochemical activity, composition and surface morphology of the layers deposited with direct current electrodeposition with various current density and additive concentration will be presented. To improve further the corrosion resistance and hardness of the coating, the possible incorporation of nanoparticles such as mesoporous SiO2 and halloysite particles were investigated at different pH of the electrolyte and various current density in the presence of the additives. The effect of nanoparticle incorporation into the layers on the composition, structure, and morphology and corrosion resistance will be presented.
REFERENCE: [1] Izaki, M., Electrodeposition of iron and iron alloys, Modern electroplating, 2011. 4: p. 461-481; [2] A. Miko, R. Hempelmann, M. Lakatos-Varsanyi, and E. Kalman, Iron-phosphorous layers deposited by pulse electrochemical technique, Electrochemical and solid-state letters, 2006. 9 (8) C126-C130.

The paper is devoted of verification of possibilities of evaluation of initial changing of properties and behaviour of selected polymeric isolation of cables after defined temperature loading simulated of external operational conditions and simulated temperature loading evoked by current loading. There are evaluated initial properties and behaviour of selected polymeric cable isolations and properties and behaviour after natural ageing process and controlled accelerated ageing process during higher temperature loading and different time of exposition to the higher temperature. The method of x-ray fluorescence analysis is used for evaluation of differences of changing of properties and behaviour of polymeric isolation cable materials after natural ageing process and after accelerated controlled ageing processes. There are verificated the possibilities for analysis differences in behaviour of polymeric insulation materials after different ageing process. The paper is namely devoted by verification of the possibilities analytic methods for evaluation initial of changing of properties and behaviour by nanoindentation methods for analysis very small differences in mechanical properties and behaviour of surface layers of polymeric materials used in the application isolation of cables. There are optimized the parameters of nanoindentation measurements for analysis of differences in hardness and elastic plastic behaviour.

The work presents the microstructure, chemical composition and mechanical properties of Inconel 686 claddings after high - temperature corrosion in environment of aggressive gases and ashes.
To produce the Ni - base coating the QS Nd:YAG laser cladding process was carried out. As the substrate used 13CrMo4-5 boilers plate steel. Ni - base alloys characterize the excellent high-temperature corrosion resistance, good strength and good ability to work in aggressive environments. Formed clad had good metallurgical bonding with the substrate material and sufficiently low amount of the iron close to the clad layer surface. After corrosion experiment the oxide scale on the substrate and clad created. The scale on 13CrMo4-5 steel had 70 μm thickness while the scale of the clad had less than 10 μm. The microstructure, chemical composition of the obtained clad and scales were investigated by means of a light microscope,
the electron microscopes (SEM, TEM) equipped with the EDS detectors.

The presented work constitutes the continuation of the previous research concerning the measurement of the tribological properties of different zinc coatings deposited to fasteners. The applied heat treatment was mainly focussed on increasing the hardness of the outer layer of the zinc coating and increasing wear resistance. Fasteners (M12-60 screws) were galvanized in industrial conditions (according to PN-EN ISO 10684), and next were subjected to the heat treatment in an electric chamber furnace. Screw sets were subjected to analyses using the Schatz ® Analyse device. It lets for determining the quality of fasteners in realistic working conditions (e.g. assembly) and according to international standards. Results of attempts allowed for determination the rate of the friction of screws and nuts on the thread and under the head and verification of the coating heat treatment influence on measured parameters - microstructure changes, micro-hardness distribution and coating topography of the zinc coating before and after the heat treatment.

Nowadays, the porous coatings enriched in determined chemical elements on CP Titanium Grade 2 may be obtained by Plasma Electrolytic Oxidation (PEO), the process also known as Micro Arc Oxidation (MAO). It should be pointed out that DC, AC, or pulse voltage may be used to create these coatings; however, their structures, chemical composition and mechanical properties are always different than the substructure (matrix). It should be also noted that they may be used in a wide range of applications, such as biomaterials, catalysts, sensors as well as wear resistant coatings. In this paper the fabrication and characterization of PEO coatings obtained on CP Titanium Grade 2, which are porous and enriched in biologically active chemical elements, are presented.
This work was supported by a subsidy from Grant OPUS 11 of National Science Centre, Poland, with registration number 2016/21/B/ST8/01952, titled “Development of models of new porous coatings obtained on titanium by Plasma Electrolytic Oxidation in electrolytes containing phosphoric acid with addition of calcium, magnesium, copper and zinc nitrates”.

The aim of this paper is to examine the effect of the oxide layer thickness on the absorption of IR radiation in the inert gas atmosphere. The oxide layers are created by the controlled heating method, while the different thickness of layers is achieved by changing the heat input. The tests were performed on steel EN 10083-2: C45. The absorption was measured in UV - MIR spectral region. The samples were afterwards processed by HPDD laser. Firstly, the hardening was carried out in air but second experiment was performed in inert gas atmosphere. The thickness and hardness of laser hardened layer were considered. The chemical composition of oxide layer on the surface of the sample was inspected by grazing-incidence x-ray diffraction. The difference between hardening in inert gas atmosphere and hardening in air was assessed.

The paper is devoted by simulation of conditions of sun radiation in correlation with real loading in operational conditions of selected polymeric materials. In the second the paper is devoted by simulation of temperature conditions of loading again in correlation with temperature loading in real operational conditions of selected polymeric materials. There are tested sensitivity of selected analytic methods in connection on running processes of ageing of polymeric materials for evaluation of initial of radiation ageing and temperature ageing with possibilities of prediction of evolution of running changing of properties and behaviour of evaluated materials. There are tested method x-ray fluorescence analysis and parameters of this method are optimized for increasing sensitivity for evaluation initial changing of properties and behaviour of tested materials on the base the first results. Indentation methods are used for analysis of changing of mechanical properties and behaviour namely static nanoindentation and scratch nanoindentation. These methods are optimized on the base the first results too. There are used more possibilities for control of indentation tests by the use different modes of measurements namely simple and cyclic measurement, setting different rate of loading and using different type of indentors for realization of measurements.

The bond strength of a plasma-sprayed Al2O3 coating with a steel surface was investigated. Various cooling options for this surface were used in plasma spraying. It was found that the best result is achieved with active water supply to the plasma spraying zone. The interface between the Al2O3 coating and the deposited surface was investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). No evidence of chemical interaction between the Al2O3 coating and the deposited surface was found. At the same time, it was established by quantitative X-ray phase analysis that when the water is supplied to the sputtering zone, the phase composition of the Al2O3 coating significantly changes. The amount of α-Al2O3 and β-Al2O3 decreases ~ 5-fold, and the amount of γ-Al2O3 increases more than 1.5 times. Given the differences in the physico-chemical properties of Al2O3 modifications, this was probably the main reason for the increase in the adhesion strength of the Al2O3 coating with the sprayed surface when sprayed with water supplied to the sputtering zone.
The technical solutions found were used to form a sublayer of γ-Al2O3, on which the Al2O3 coating was applied already without water supply to the sputtering zone. The resulting coating had a hardness of HV 821 kgf / mm2. The material of the underlayer and the coating material in the contact zone were a single whole. Based on the results of the work, the industrial technology of applying Al2O3 coatings was improved by the method of plasma spraying.

Lead bulls are often stored in an inappropriate environment with the presence of organic acids on which leead is sensitive. The aim of this work was to test compounds inhibiting the lead corrosion due to acetic acid vapors. Ideally those that will have better application and surface properties than the widely tested carboxylic acid salts. Sodium decanate, Pragokor O 170, benztriazole, cyclohexylamine, thiourea and sodium benzoate were used. The effect of individual inhibitors was tested by the resistometric method on the ground surface for 2 hours immersed in the inhibitor and on the surface coated with the carbonate-based corrosion products with an immersion time in inhibitor for 2 and 24 hours. Three of these surface-treated sensors were exposed to 0.001 mol/l acetic acid. To evaluate the appearance and characteristics of the lead surface after treatment with the inhibitor, the same prepared samples were used. It has been found that all of the used substances form a protective layer over the lead. The highest efficiency was achieved by cyclohexylamine and benztriazole. The smallest surface changes occurred in sodium decante and benztriazole. These protective surfaces were also highly hydrophobic and showed the best mechanical properties.

The authors gratefully acknowledge the financial support by the Czech Ministry of Culture under NAKI II programme (No. DG16P02R040).

Thermal barrier coatings with different compositions are used to increase efficiency of gas turbines. The gas turbine efficiency can be improved by increasing the temperature of hot gases entering the turbine. The inlet temperature to the turbine is limited by the metallurgical considerations. Researchers are trying to develop most suitable material combinations for thermal barrier coatings (TBC) to improve its efficiency. In present work, combination of multilayered surface coatings are developed using plasma spray method. A combination of yttrium stabilized zirconia (YSZ) and Lanthanum titanium aluminum oxide (LaTi2Al9O19, LTA) powder is used as a top coat material. A bond coat of 90 µm thickness of NiCrAlY is applied on the substrate of Inconel 718 after shot blasting. LTA layer of thickness 100 µm and 150 µm is applied on the top. Hot corrosion study including cyclic and isothermal hot corrosion tests are carried out in presence of Na2SO4 and NaCl salts in 3 : 1 weight proportion at 900OC. Weight gain increase is very negligible. Surface morphology of the coating has been evaluated using field emission scanning electron microscopy. Results obtained are correlated and discussed.

Diamond has a number of unique properties, such as high hardness, wear resistance and thermal conductivity, but it is impossible to obtain compacts from the diamond crystals without any binder. Diamond-copper composites have attracted a lot of attention in recent years as promising heat sink materials. Low affinity of copper to carbon makes the preparation of fully dense copper-diamond composites quite challenging. Because of residual porosity, the thermal conductivity of copper-diamond composites can be lower than that of monolithic copper. To solve this problem, metallic coatings can be deposited on the diamond surface to increase the wettability of the crystals by copper.
In the present study, W- and Mo-containing coatings on diamond particles were obtained by rotary chemical vapor deposition (RCVD) and Spark Plasma Sintering (SPS). Tungsten carbonyl was used as a precursor in RCVD, while W and Mo metal powders were used as sources of metals in the deposition of coatings by SPS. By varying the coatings formation method and conditions (duration of exposure, deposition temperature), different features of the diamond/metal interaction were revealed. For obtaining copper-diamond composites, the SPS method was used. We investigated the influence of the metal coatings on the diamond crystals on the microstructure, relative density and thermal conductivity of the copper-diamond composites.

The tools used for milling and grinding can have a limited lifetime due to excessive wear. Their lifetime can be prolonged by application of suitable coatings. Highly wear resistant coatings can be easily applied by means of laser cladding. The goal of this study is to effectively prolong the lifetime of milling screw used in sawdust processing. The coating consisting of tungsten carbide spherical particles in NiCrBSi matrix excels with high hardness and excellent wear resistance. This coating is laser cladded to the areas of the tool, which degrade first due to rapid wear rate. The cladded milling screw is then tested in production. The treated part exhibit with significantly less wear rate than the untreated part of the tool. The lifetime of the whole milling screw is prolonged, however additional optimization of areas treated by cladding can bring further improvement.

In this study nanocomposite WO3-SiO2 coatings were deposited on glass and Si (100) substrates by sol-gel dip coating technique. Tetra ethyl ortho silicate (TEOS) was used as the precursor, ethanol as solvent and NH4OH as catalyst for the preparation of SiO2 sol and WO3 nanopowders were added in different volume concentrations. The effect of WO3 addition into the starting sol and different dipping-rising cycles on the properties of WO3-SiO2 nanocomposite coatings were investigated. Microstructural properties of the coatings were characterized by cross-sectional SEM observations and EDS was used to determine the coating composition. Spectrophotometer has been used to measure the optical properties of WO3-SiO2 coatings. The crystallinity of the coatings was studied by grazing incidence X-ray diffraction (XRD) analyses.

A numerical-analytical approach has been presented in a Ph.D. thesis, to predict abrasive damage of iron ore pellets (IOP). An analytical model for material loss during collision was proposed based on the mechanistic model of Ghadiri and Zhang. Normal contact force of collisions is specified as the most affective variable parameter of the model, which is calculated using discrete element simulation in LIGGGHTS. Hence, Normal contact force of collisions is strongly influenced by the geometry of handling equipment, a numerical investigation would specify damaging zones of the handling line of IOP. In present research, the important zones of conveying system in iron-making plant of Mobarakeh Steel Company are simulated to study the damaging points. According to the results of present research, Geometrical and metallurgical improvement of the equipment (such as chutes, diverters, etc.) would be more feasible in the future works.