Seznam abstraktů 2017: SEKCE D - MODERNÍ TRENDY V POVRCHOVÉM INŽENÝRSTVÍ
Datum: 24.5.2017
The paper wants to be a review of the own researches realized in the nonconventional treatments domain, corresponding to the magnetic field treatments applied to a steel of construction for industrial parts, for gears and some parts of industrial machines. The magnetic field applied under certain conditions during the cooling process of the sample in the case of the improvement treatments, modifies the properties of steel, increases the hardness, the corrosion resistance and the wear resistance.
The studies on tribomodels during the dry friction processes determine the wear intensity for a certain type of tribomodel and for a certain type of material. An Amsler stand was used. The experimental study uses two distinct values of task of loading (Q). The rollers with different diameters were used in order to obtain different sliding degrees (ξ). Diffractometry aspects and a statistical modeling completed this study.
A thermo-chemical treatment in plasma with diffusion applied at a temperature under the temperature of the thermo-magnetic treatment leads at high wear resistance and better characteristics of the superficial layers of the steel.
The contribution deals with possibilities of using infrared thermography for inspection, diagnostics and control in laser welding technologies. Laser welding methods and infrared thermography inspection methods are also introduced. Possibilities of non-destructive infrared thermography testing are demonstrated on examples of laser welded plastic samples and inspection of protective glasses of laser scanning heads used in laser welding technologies.
Mechanical properties of thin films are crucial in many applications. Nowadays only the nanoindentation technique is often considered as standard measurement technic. Unfortunately, data analysis of the nanoindentation is complicated and some very important parameters, as e.g. yield point, cannot be measured. The bulge test is known as a non-destructive method to determine mechanical properties of thin films and free standing membranes. The aim of this project is to develop bulge test apparatus and measure precisely properties of commercially available membranes. Furthermore, thin film of interest will be deposited on a membrane with known properties and bulge test will be performed on the bilayer specimen. Subsequently, the material properties of the thin film will be obtained using FEM analysis. So far, the apparatus for pressurising and pressure measurement was constructed using industrial grade pneumatic piston, syringe pump and low pressure transmitter. Square and rectangular silicon nitride (Si3N4) thin films of various thicknesses were tested by means of standard pneumatic bulge test and reverse bulge test, i.e. membrane was bulged in due to negative differential pressure. Different methods of the specimen clamping were established. Surface topography was measured using laser interferometry and optical system developed for this purpose. The whole surface of membrane was monitored during bulging. Majority of other research groups usually measure only the position of the top of the bulge, however, knowledge of the shape of the whole membrane enables more precise determination of materials parameters. The analysis of the experimental data using FEM is in progress.
In the paper a quality of the thermal diffusion coating dedicated for anticorrosion protection of fasteners was assessed. Because of similarity of parameters and structures, properties of the inspected coating were compared with effects get as a result of hot-dip galvanizing. Coatings were deposited in industrial conditions on flat samples and screws made of 23MnB4 steel. The corrosion resistance of coatings was measured by neutral salt test – NSS. The kinetics of the corrosion on flat samples was additionally determined basing on the computer image analysis. Microscopic examinations concerned the thickness, the structure and the state of the surface of assessed coatings. Conducted EDS analysis allowed for comparing the structure of coatings with the theoretical model. It was stated that the thermal diffusion coating was admittedly less resistant to corrosion in the examined environment, but as a result of the further optimization of process parameters and the method of surface preparation the significant improvement in anticorrosion properties is expected.
The study determines the effect of different surface preparation grade cast iron GJL-250 on the mechanical properties of the hot-dip zinc coating. The samples for testing were taken from the parts used in the construction of power overhead lines. Mechanical properties and wear intensity of the zinc coating was determined by tribological tests in conditions of dry friction, that were performed using a tester T-11. Study allowed determination of the coefficient of friction of the zinc coating with dependence to the surface preparation method. In order to supplement the test results nanohardness on the cross-section of the applied coatings were measured. Measurements were carried out of the maximum load 20 mN using a diamond Berkovitch indenter type. Additionally, in order to determine the mechanisms of the coating damage macroscopic and microscopic analysis and measurements of surface texture are carried out. On the basis of the results of studies, the differentiotion in the degree of the coatings wear deposited after different method of surface preparation were evaluated. The research showed that the use of high-temperature oxidation as a way of surface preparation of the cast iron may decide on the tribological properties of the hot-dip zinc coating.
The zinc coating and/or zinc alloyed coating is one the most frequently used type of corrosion protection. This study was carried out to investigate and evaluate the corrosion behaviour of aluminium zinc alloy coated steel sheet at atmospheric condition. The aluminium-zinc hot dip coating was exposed for 10 years at industrial atmospheric test site Kopisty, Norther Bohemia. The article gives the overall evaluation of long-term exposed coating and progress of degradation of coating on cut-edges.
The paper reports on the assessment of multiple surface treatments of shafts rings in contact with radial seals. The scope was to choose two best treatments to be used in application-scale model stand to recommend the optimal solution for the manufacturer. Four commerically coated samples, one hot-blued sample and one sample treated with commercial nanofilm Dronte Nano were used in this study; one untreated sample was used as a reference. In this step, the mechanical tribological properties were measured using nanoindenter NanoTest Vantage (Micro Materials) using diamond and steel tip respectively and evaluated using confocal (Olympus LEXT) microscopy and canning electron microscopy (Zeiss EVO25). Nanohardness, effective Young’s modulus, adhesion strength, coefficients of friction and wear, respectively, were evaluated. Aditionally, the water droplet and oil droplet contact angles were measured for every sample.
Plasma nitriding is widely used as a final operation to improve wear, fatigue and corrosion resistance of industrial parts. Nevertheless, corrosion resistance can be further increased by post-oxidizing or by manganese phosphate conversion coating. This paper considers the duplex treatment of plasma nitriding and manganese phosphating of 42CrMo4 steel surface, widely used for manufacturing of breech mechanism in the armament production. Plasma nitriding was carried out at 500 °C for 15 h in different nitriding atmosphere having hydrogen and nitrogen gas flow ratio with 3 to 1 l/h and of 1 to 3 l/h. Plasma nitrided steel samples were manganese phosphated (without lubrication). The treated samples were characterized using metallographic techniques, micro-hardness and NSS corrosion tests. Different compound layer thickness under different nitriding gas ratio was confirmed. The X-ray diffraction analysis (XRD) confirmed different volumes of ε-Fe2-3N, γ´-Fe4N nitrides in the compound layers and hureaulite Mn5 (PO3 (OH))2 (PO4)2 (H2O)4 in the manganese phosphate coatings. Visual and gravimetric evaluation was carried out and corrosion rates modified to weight gains were calculated for corrosion evaluation. After removing of corrosion products weight losses were measured and pitting factors were calculated. Duplex treatment (manganese phosphating after plasma nitriding) also displayed increased corrosion resistance and suppressed pitting propagation in comparison with the plasma nitrided steel samples and a potential to further increase of corrosion resistance of plasma nitrided structural steels.
Carbonitriding combines the effects of saturation of the surface of the component with nitrogen and carbon simultaneously. The layer has a hardness approaching 1000 HV and is highly resistant to galling and abrasion. For this reason, carbonitriding components are used in applications with high demands on thermal load and wear resistance (e.g. valves of internal combustion engines, segments of crankshafts, etc.). Mostly in case of components after carbonitriding are not required subsequent grinding due to a minimum increase of the dimensions and small changes in surface roughness. Presented work documents a change of parameters of the surface topography of 16MnCr5 steel after carbonitriding in gas and plasma. The layers were applied to the grinded surfaces of the specimens and then compared. The surface morphology and 2D and 3D surface parameters were measured. After carbonitriding was found considerable porosity of the resulting layer, especially after carbonitriding in gas. Applications of carbonitriding both in gas and plasma resulted in only a slight increase observed roughness parameters.
In this study, the cyclic loading of steel samples 41CrAlMo7-10 (1.8509) were made. This steel is suitable for plasma nitriding proces. The experiment included 4 different plasma nitriding procedures. The differences were applied in plasma nitriding atmosphere and procedure duration. Then follow-up a fatigue test. The fatigue tests were carried out in accordance with the CSN 42 0363 Fatigue Testing of Metals, Methodology of Testing in the machine R.R.Moore L2568 of Instron Co. Fatigue tests were compiled graphically and numerically using Wöhler`s (S-N) curve in a semi-logarithmic form. The testing was stopped after reach the fracture of tested sample or after 107 cycles. Area of study was fatigue fracture. Specifically, part of fatigue fracture around inclusions and their vicinity. This part is known as fish-eye and has specific shape and morphology in terms of surface topography. The surface topography of fatigue cracks were evaluated on Talysurf CCI. Roughness parameters were tested in this area at six defined lines from fatigue crack initiation.
Thin film solar technology is used various devices that convert the sun light into electrical energy. These applications have been crucial for human life since they supply us clean and alternative energy sources. For this application many components can be used Cu2S ,CdTe, CIGS, CNTS, and TiO2etc. TiO2 is one of them and preferable for this technology because of its good electrical and physical properties.
TiO2 based solutions prepared completely transparent are coated on ITO (indium tin oxide coated) glass with different Ph values, sol gel dip coating method. This coated glass annealed with same temperature and same holding time.
Previous research shows that pH factor has significant effect on the surface morphology of films. Surface area and surface roughness are pH dependent parameters that very important for light conversion efficiency.
In this study, the effect of pH on thin film surface morphology is investigated. 5 different Ph values sols are coated on ITO glass. These glasses annealed in the furnace with same temperatures and same holding time.The results are determined with several methods. Chemical properties determine by X-ray photoelectron scanning (XPS), X ray diffraction scanning (XRD) surface properties and roughness values investigated by atomic force microscopy (AFM), and scanning electron microscopy (SEM)-focused ion beam technique (FIB). The XPS and XRD results show that, because of the low working temperatures there is not any change in chemical structure of TiO2. The material that we study is glass. Above 600°C chemical structure of glass can be deteriorated.We carried out our experiment below this temperature. According to the results of AFM pH is important factor on film morphology. The results are showed that if the pH increases the surface roughness parameter (Ra) is increases.
The Ni-based superalloy are generally known for their high corrosion resistance in various kinds of environment, including the high temperature. As a thermally sprayed coating, they are often used in chemical, aerospace or energy industry. Not only the corrosion and oxidation resistance, but also the stability of mechanical properties is crucial, if the coating is applied in high temperature environment. In some cases, the thermal exposition can even improve the properties by modifying of the microstructure. The thermal post treatment can increase the coatings intersplat cohesion or alloy mechanical strength through precipitation hardening. In the paper, the influence of thermal exposition and laser treatment on the microstructure and related mechanical properties of HVOF sprayed Hastelloy C-276© coating is studied in terms of SEM, XRD analyses, microhardness and wear test.
In the paper the analysis of the electron beam cladding process with wire is presented. The aim of the study was to determine the impact of technological conditions on the stability of the process as well as dimensions of the deposited layer. Cladding process was performed using four types of deposited metals.
The relationships between the technological parameters (accelerating voltage, beam current, wire feed rate and travelling speed) and the width and height of the excess weld metal were determined. The technological trials on the plate and shaft were performed. During trials the single deposit layers as well as defined cladding areas were produced. The metallographic examinations of deposit layer, based on light microscopy were conducted. The artificial neural networks and response surface methodology to analyse the process were applied.
The results revealed that the increase in the wire feed rate and beam current causes increase in the width of the deposited layers. However, the increase in the beam current did not influence on excess weld metal. Moreover, at the constant beam power and wire feed rate, the deposition height decreased with increasing travelling speed.
The response surface methods and regression equations were also used to analyse the process. The analysis showed that for equations containing square effects it was possible to obtain a better matching of the calculated values with respect to experimental values. However, in spite of the development of regression equations, it was impossible to achieve the same fit as for neural networks. This is due to the fact that for neural networks in the learning process more advanced matching functions that for other methods are used.
Datum: 25.5.2017
In this article, the reactions and optimal parameters were investigated for molybdenum layers produced on aluminum substrate using single beam ytterbium fiber laser. To produce these layers the molybdenum powder (25–45 µm in size) was placed on the aluminum sheet substrate and successfully treated – along the entire length with 16 different irradiation modes. The microstructure of the prepared samples of welded joints was observed by using a light microscope (LM) and a scanning electron microscope (SEM). Reactions between molybdenum powder and aluminum substrate were examined by energy dispersive X-ray analysis (EDX). The evaluation of optimal parameters was determined from appearances of welded joints, namely their heights and depths.
Atmospheric plasma spraying utilizing initial powder materials in micrometric size has been successfully used for various applications in different fields of the industry over the past several decades. Nowadays, the new trend in plasma spraying is to use sub-micron or nano-sized powder feedstocks in the form of colloidal suspension. This relatively new technology enables to obtain specific types of dense vertically cracked, fully dense or columnar microstructure. The aim of this work is to investigate the influence of coatings microstructure and topography on its water wetting properties. Two different microstructures, i.e. lamellar and columnar, were sprayed from chemically the same yttria-stabillized zirconia (YSZ) ceramics by means of conventional atmospheric plasma spray and suspension water stabilized plasma spray techniques, respectively. Microstructural and phase composition of the initial powders and as-sprayed coatings were investigated using optical microscopy, scanning electron microscopy and X-ray diffraction techniques. Topography of coatings surface was measured by means of non-contact optical profilometry. The YSZ coatings wettability was evaluated based on water droplet contact angle using Sessile droplet method. The coatings microstructure reveals the important role in the change of droplet contact angle, where lamellar structure was found close to hydrophilic-hydrophobic transition and columnar structure was found almost superhydrophobic.
The results of the hydrogen concentration measurements in selected products, made of steel grade 41Cr4 have been presented in the paper. The reason of the project was the failure of the tower structure and the suspicion of brittle fracture caused by hydrogen in one of the hot-dip galvanized products made of steel grade 41Cr4, found in the wreckage of the tower. Due to the fact that the opinion was formulated on the basis of the results of the hydrogen content measurements in broken product (20 ppm) it was decided to examine this problem. The hot-dip galvanized and electroplated metal elements were subjected to the research. Two types of samples: without and with zinc coating were prepared for analysis. The analysis was performed using an elemental analyser LECO ONH836. Diversification of hydrogen content on the sample cross-section was revealed after the profile of its contents. It has been found that a high hydrogen content was observed only and exclusively inside zinc coating. This means that the presence of the Zn coating in the sample affects the accuracy of the measurement of the hydrogen content and can lead to erroneous conclusions about the hydrogen embrittlement or hydrogen charging of steel. The results of the hydrogen concentration in each case should be considered carefully as measured is the total concentration of the hydrogen content, and not only the hydrogen diffusion responsible for the occurrence of hydrogen embrittlement.
The results of the corrosion resistance of hot-dip galvanized coatings obtained on bolts made of steel grade 23MnB4 has been presented in the paper. The bolts were subjected to various treatments (heat, mechanical and chemical) before application of the zinc coating. Comparative evaluation of corrosion resistance of galvanized bolts was performed by accelerated corrosion tests in salt chamber and using electrochemical methods. The bolts were exposed to an atmosphere of neutral salt spray according to standard ISO 9227:2012 and the following methods: linear polarization and potentiodynamic cyclic voltammetry according to PN-EN ISO 10271:2012. In order to correlate corrosive environment of the tests, the 5% neutral salt solution was used at temperature 35°C. Results of the study were related to the results obtained for the bolts without zinc coating.
It was found that the tested zinc coatings on the bolts are leaky and relatively short-term corrosion protection. The surface preparation of bolts before hot-dip galvanizing and the centrifugation of excess zinc after process affected on the results of corrosion tests. Therefore, in order to improve the quality of the anti-corrosion coatings on the bolts the further research are recommended in the field of the surface preparation before hot-dip galvanizing.
Silica aerogels, as well as those consisting of other metal oxides (alumina, zirconia, titania or mixture of these oxides), are extremely porous (up to 99 %) high tech materials with very high specific surface areas (1000 m2 g-1) and low thermal conductivity (below 0.02 W / mK). The typical aerogel production process includes several steps and starts with the preparation of a sol. The next step includes a casting of the sol to obtain the required gel form via sol – gel transition and its drying in a supercritical drying chamber at supercritical conditions of CO2 to obtain the desired product. Hence, it is of critical importance to determine how processing parameters (type of solvent, catalyst, surfactant, a medium of drying, temperature, pressure, the presence of a surfactant template) influence the microstructure, morphology, transparency and other properties of the obtained aerogels.
In this work, we studied the effect on three synthesized systems: SiO2-Triton, SiO2-PVP and SiO2-F127 using TMOS, MeOH-NH4OH-H2O at constant molar ratios of reactants 1:7:0.7:2.7, respectively.Chemical, structural and morphological results were performed by using FTIR and SEM techniques. SEM analysis demonstrated a change in agglomerate size distribution (5-10 nm) depending on the system. Furthermore, the increase in the amount of F217 agent increased both the density, measured by sample dimensions, of produced SiO2-F127 aerogels from 0.02 to 0.075 g cm3 along with the pore size.
The subject of the study was the fastening M 6 made of low-alloy steel manufactured in large quantities, hardened. The aim of the study was to compare the parameters of galvanic process Zn Ni using the traditional method with the new method using the membrane system. The study was conducted on a pilot production line using electrolytes operating in industrial conditions. An analysis of the composition of both baths was performed and their current efficiency. The time of application of the layer and the uniformity of the decay of the alloying elements in the coating were assessed.
The article deals with influence of chemical-heat treatment on porosity in surface layers. Different types of chemical-heat treatment were used for evaluation of development of pores in white layers. C 45 steel in martensitic state was used after quenching for experiments. Experiments are focused on using of plasma nitriding and gasseous nitriding process for surface treatment of machine parts. Samples were evaluated by metallographic, GDOES and SEM methods. The results of experiments showed the main difference between different types of layers applicated by different methods. Finally it was reached the huge reduce of pores creation after new developed conditions of nitriding. This type of nitriding is really suitable for application to machining parts. This technology caused really low changing of size after application of layers.
The aim of this paper is to examine the effect of surface oxidation volume, represented by the thickness of the oxide layer, on the absorption of IR radiation. The oxide layers are created by the controlled heating method. The scanning laser system is used for this heating process. The difference in oxide layer thickness is achieved by changing the irradiation energy. The tests were performed on steel EN 10083-2: C45. The absorption was measured in UV – MIR spectral region. Significant value for this paper is absorptivity for wavelength 808 nm. This is the wavelength of HPDDL laser, the system is used for laser hardening. On this system will be tested the absorption in further research work. The width of oxide layer was measured by scanning electron microscope. The results are demonstrated in comparative graphs.
Datum: 26.5.2017
Laser remelting of thermally sprayed coatings is a promising possibility how to improve their functional properties. However, it requires precise control of processing parameters to achieve desired depth of remelting. In this study, the near-infrared (NIR) camera is used to measure the achieved depth of remelting during diode laser remelting of HVOF sprayed coatings. Possibilities how to evaluate the temperature field in the melting area are presented. The width of melting pool is calculated and it shows high correlation with achieved depth of remelting. The study shows that the NIR measurement can be used for controlling the depth of remelting during a laser remelting of coatings.
Failure and wear of tools made of high speed steel (HSS) is a common cause of production slowdowns or interruptions. Renovation of structures made of high-speed tool steel can significantly reduce production costs and time needed for resumption of production.
The Tool steel of HSS 23 type (M3/2) was cladded on substrate of the same type of steel and heat-treated. The influence of hardfacing parameters on both macro- and microstructures was studied by light and electron microscopy and by extreme property mapping (XPM). Development of hardness from substrate to deposit was measured by Vickers method. Metallurgical bond between parent material and deposit was created. The deposits are free of cracks and porosity.
Inhibition of mild steel corrosion in 1 M HCl solution by alkylimidazolium bromides was investigated using electrochemical and weight loss methods. The studied ionic liquids showed appreciable inhibition efficiencies. Polarization measurements proved that the studied ILs are mixed-type inhibitors with predominantly anodic inhibition. The inhibition efficiency increased with the ionic liquid concentration and with the length of the alkyl chain. The values obtained from the polarization curves and Nyquist plots are in good agreement. The highest inhibition efficiency reached for the 1-octyl-3-methylimidazolium bromide was 93%. The Gibbs energy of adsorption was calculated by means of the Flory-Huggins isotherm and El Awady Thermodynamic-kinetic model.
Surface integrity is a complex characteristic which includes all effects which may act on the surface. In particular, the roughness parameters, residual stresses or changes in the microstructure. About this is spoken particularly in connection with machining, which is considered as final treatment. In this paper an attempt was made to move the concept of surface integrity in a somewhat different plane. The main attention was paid to the problem of the integrity of the surface of cast iron. In this case, the problem is complicated because of heterogeneous structure in which there is present a metal matrix and the precipitated graphite. In this article an attempt was made to influence the integrity of the surface using a non-standard processing the surface with electrodeposited layer of Fe.
The contribution deals with study of adhesion organic coating systems for the repair of a damaged vitreous enamel coat. Vitreous enamel is resulting product of the physiochemical reactions in the process of heat glass forming of the complicated chemical constitution with next components of the inorganic character and connecting nesting characteristics of the glass and ceramic with ability of the adhesion to metal. Damage of the vitreous enamel coat arises particularly during of transport the product and its handling and assembly of enamelled parts for agricultural, energy and water industry. For experimental works were used two types of coating systems based on epoxy and polysiloxane. Experimental results show that the vitreous enamel coat can be repaired by the above-mentioned organic coating systems. According to the results of adhesion tests according to EN ISO 16276-1 (Pull-off Test) and EN ISO 16276-2 (Cross-cut Test), the adhesion of organic coatings on vitreous enamel coat is suitable in value in the range from 4.0 to 5.2 MPa (according to Pull-off Test) and degree classification in the range from 0 to 4 (according to Cross-cut Test and according to pretreatment of surface vitreous enamel coat). Use of thus repaired vitreous enamel coat is limited by the properties of the organic coating in contact with aggressive corrosive environment, temperature, drinking water and food.
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