Seznam abstraktů 2016: SEKCE D - MODERNÍ TRENDY V POVRCHOVÉM INŽENÝRSTVÍ

The technologies of surface modification govern wide range of procedures, addressing various purposes. The most common is the enhancement of wear resistance and corrosion protection, but also other functional properties, such as protection against high temperature, modification of electrical or heat conductivity or compatibility with biological tissues. Essentially, two basic attempts are used to modify the surface properties. First is based on modification of substrate sub-surface layers microstructure, usually by heat treatment or alloying, or by their combination. Technologies of surface hardening, case hardening or nitriding are the typical examples. The second possibility is to add material of different composition and properties on the surface, building a coating. Various types of coatings were developed during time being, making the choice of suitable one for specific application rather difficult. Nevertheless, the coatings can be distinguished according to their purposes, e.g. high temperature protection, or according to the principle of their deposition.
In the paper, the attention is paid to the group of so called “thick” coatings, including the thermal sprayed and laser clad coatings. The traditional methods of spraying are reminded and compared with lately developed ones. The technologies are discussed in terms of their application and coatings materials. At the end, the advantages of hybrid coatings are presented, indicating the possible future trends of surface modification technologies.

The influence of surface preparation of steel 41Cr4 on the structure and corrosion resistance of the zinc coating has been presented in the paper. The aim of the study was to determine the method of surface preparation fittings for overhead power lines made of steel 41Cr4 guaranteed to obtain zinc coating of a required thickness and high corrosion resistance.
Prepared materials were subjected to an abrasive blasting – steel shot GL40 and chemical treatment – pickling (hydrochloric acid) and fluxing (TIBFLUX60). The hot – dip Zn galvanizing process was conducted in industrial conditions in 457 oC. The (Zn) - coating morphologies and sub-layer thicknesses were evaluated on the basis of metallographic analysis and corrosion tests. The correlation between the results of corrosion test and coatings morphology was determined.

The paper shows the evaluation of delamination of HDG coating. The HDG coating adhesion was evaluated by impact test and by pull-off test. The effect of substrate steel chemical composition, metallurgical conditions and other parameters influencing the quality of zinc coating, mainly the intermetallic phases, are described. The silicon content in aluminium-killed steel was identified as crucial factor for tested samples. The result of adhesion test corresponds to structure of zinc coating.

Laser surface texturing (LST) is one of the methods for obtaining surfaces with specific properties. In this paper there was studied influence of initial surface state of sliding bearing steel on laser texturing of this material. Initial surface with roughness Ra = 0.13 µm was used for providing shifted laser surface texturing (sLST) by ultrashort laser pulses. On initial “rough” surface laser formation of above-surface-growth (ASG) structures was found. Morphology and chemical composition of the ASG structures were analysed by SEM with EDX spectrometer in comparison with initial surface. Two ways of regression of ASG structures were investigated - fine mechanical repolishing of surface for Ra = 0.01 µm and optimisation of laser processing parameters. It was found that the most suitable method of ASG structures regression is optimisation of laser processing parameters in comparison with mechanical repolishing. Regression of ASG structures formation by optimisation of laser processing parameters was provided by application higher laser fluence. Temperature field distribution for different laser processing parameters is determined from semi-planar thermal model. Heat accumulation effect is evaluated for both - sLST by simple pulses and burst mode. Advantages and disadvantages of presented methods for regression of ASG structures formation were discussed with theoretical background. Presented results improve understanding of physical principles of ASG structures formation and the ways for their regression.

The study presents the results of the corrosion resistance research of DC01 steel, protected by VentureShield™ VS 7510 E film. The assessment of corrosion resistance of the examined material was conducted by using linear polarization method, according to the EN ISO 10271:2012 standard. Various corrosion substances were used, i.e. disinfectants (based on ethanol) and bodily fluids. The data was referred to the research results of DC01 steel surface corrosion not protected by film.
The results confirm that VentureShield ™ VS 7510 E film applied as a protection coating provides good protection against corrosion, in the contact with disinfectants and bodily fluids and may be used for the protection of ambulances interior, as well as in hospital environment.

Plasma sprayed alumina coatings find numerous applications in various fields, where they enhance the properties of the base material. Examples include thermal barriers, wear resistance, electrical insulation, and diffusion and corrosion barriers. A typical structure of plasma sprayed coatings, containing a multitude of voids and imperfectly bonded interfaces, gives them unique properties – particularly low thermal conductivity, high strain tolerance, etc. However, for certain applications such as permeation barriers or wear resistance, these voids may be detrimental.
This paper reports on the first experiments with remelting of plasma sprayed alumina coatings by electron beam technology, with the purpose of densifying the coatings and thereby eliminating the voids. Throughout the study, several parameters of the e-beam device were varied - beam current, traverse velocity and number of passes. The treated coatings were observed by light and electron microscopy and the thickness, structure and surface morphology of the remelted layer were determined and correlated with the process parameters. Based on the first series of experiments, the e-beam settings leading to dense and smooth remelted layer of sufficient thickness were obtained. In this layer, a change of phase composition and a marked increase in hardness were observed.

In the paper reasons of damage of zinc galvanized fasteners – self tapping screw M8x25 mm or screw drawing M12x130 were analysed. Examinations concerned analysis of fractures created as a result of screws cracking, the verification of structure correctness achieved after the heat treatment, hardness measurement at the screws cross section as well as inspections of the hydrogen content. Based on conducted examinations it was stated that the main reason of analysed screws cracking was steel hydriding - hydrogen brittleness which could take place on individual stages of the production process. Measured hydrogen content much more exceeds the acceptable values, and observed fractures are characteristic of brittle cracking.

Technological lasers are a useful tool for laser welding as well as other material treatment and production processes. Lasers with an optical scanning head are the important group of technological lasers. A protection glass of the scanning heads can be dirtied in the case of some technological operations. It is connected with its degradation and subsequent production quality reduction. Active thermography is one of the methods, which can be used for the protection glass inspection. The method uses a non-contact detection of a tested object thermal response to its external excitation. Experiments performed showed that a dirtying of the protection glass can be inspected using flash-pulse thermography. Experimental set-up for the flash-pulse thermographic testing and results of tested samples inspections are presented in the contribution. Possibilities, advantages or disadvantages and possible development of the thermographic inspection of laser scanning heads protection glasses are discussed.

By vacuum-arc deposition of multicomponent Ti+Zr+Nb+Cr cathode in nitrogen atmosphere, (Ti-Zr-Nb-Cr)N coatings have been deposited on steel substrate. Such systems of coatings seem to having prospects as protective ones for couples of friction and cutting tools. Mechanical properties of the (Ti-Zr-Nb-Cr)N coatings have been studied using X-Ray diffraction (XRD), nanohardness measurements and high-temperature tribometer . The multi-component (Ti-Zr-Nb-Cr)N coatings are found to be a simple face-centered cubic (FCC) solid solution. The structure of the coatings is mainly composed of NiTi0.64Zr0.2, TiN, ZrTiNb, ZrNb, NbTiN2, TiCr, Ti phases. Mechanical and frictional properties of multi-element coatings were also studied.

Nitride nanostructured coatings were investigated in the work, which are based on high entropy alloys. The coatings were deposited by vacuum circuit-arc method of cathode evaporation on steel samples when applying different potential on the steel substrate and the residual pressure in the chamber. The chamber was supplied by molecular nitrogen for nitride formation. The thickness parameter effect on its hardness of the multilayer system was shown. The phase composition and mechanical properties were analyzed by analysis methods such as XRD (X-Ray diffraction) and Tribometer measurement. Mechanical characteristics were studied using nanoindenter (Triboindentor) in dynamic mode. It was found that the hardness of the coatings formed essentially depends on the pressure of the reaction gas.

This paper presents the research focused on surface defects of galvannealed car body sheets. The fragments of engine’s paneling cover after press forming as well as steel sheet used for its production in as-delivered condition (prior to press forming) were investigated. The fragments of the sheet at the beginning, center and end of a coil and also from the left side, center and the right side of steel bandwidth were studied. The assumed scope of studies has covered the investigations of zinc coating morphology, studies of zinc adhesion, steel sheet material formability tests, scratch tests, defects analysis, and analysis of steel sheet material in terms of its usability for zinc coating. The fragments of paneling were cut out in the spots where defects, i.e. protrusions, have been found. Defects defined as protrusions occurred as a result of particle or particles conglomerate depositing on the surface of the die. Particles causing protrusions were identified both as steel fragments most likely originating from steel sheet sheared by the edge of the die, and fragments of spalled zinc coating, most likely in the form of conglomerates. The size of zinc coating spalls, indicated that only their conglomerates may result in the protrusion formation. Moreover, the chemical composition of steel, especially too large silicon content, may also be the reason of easier spalling of fragments of zinc coating. The investigations also showed, that non-woven fabric used for cleaning the dies surface contained the particles, the presence of which on the surface of the dies can be considered as the origin of defects.

PTA surfacing is in manufacturing widely used technology of increasing lifespan and utility characteristics of machine componnents. There is a wide range of alloys which can be used as filler material, however plasma cladding of High Speed Steel is (HSS) not yet frequently used. HSS’s are the materials for fabrication of tools in machining, forming, forging and in the others applications where high wear resistance is needed. The deposit tested in this study was cladded with three different frequencies of plasma current. Two-layers deposits were studied metallographically and tribologically. It was found that hardness of deposits is higher than 750HV, and structure contains finely distributed carbides of Vanadium, Chrome, Molybdenium and Tungsten. Tribological testing was performed on dry sand rubber whell apparatus and it was found that wear resistence depend on frequency of plasma current.

As a growing concern over the degrading environment worldwide, the main aim of the today industries is to wit the processing technique that is ecofriendly, efficient and as well as economical, it should be accomplished the processing wide-ranging variety of material like metals, non metals, ceramics and composites. Processing of material with the microwaves is an emerging field and because of its capability of processing wide variety of materials like ceramics, metals, non metals and composites and its distinctive characteristics like selective heating, volumetric heating, less processing time and economic factor attract researches to investigate more in this field. This Review paper comprehends the fundamental mechanism of microwave processing of materials, recent development in the field of microwave processing at global level and their advance research directions

The paper presents the influence of the forming way of test pieces on measured values of the mechanical properties of steel for plastic cold processing. During research the two-dimensional samples were analysed after forming by die shearing, milling and electrical discharging, at an angle: 0, 45 and 90o. Examinations concerned analysis of changes of surface microstructure, degree of grains deformation, evaluation of the surface state – roughness, surface development factor. The side sample surface was checked from the viewpoint of macrostructure and topography changes determined by PhaseView optical assembly for 3D surface scanning. In the elaboration the basic mechanical properties were compared, i.e. tensile strength, yield point, elongation, impact strength. It was stated that despite the applied forming methods have a large impact to the test pieces surface character there is no essential changes in the values of measured mechanical properties.

The paper summarizes the result of laser cladding experiments design to observe the influence the mutual angle of the cladding head and treated sample. The system, combining solid state disc laser with power up to 5,3 kW and cladding head with coaxial powder feeding, was used. The clad geometry is evaluated for the different position of the sample and different incident angle of the cladding head. The goal of the work is to determine the maximal incident angle in which the cladded coating is unaffected and based on the result determine the minimal internal diameter which can be cladded with given equipment. Then, the half tubes with small internal diameter are cladded and the geometry of the coating is verified.

Laser cladding is a progressive technology enabling to deposite coatings in thickness higher than 1 mm. In comparison with the conventional overwelds it offers the advantage of thinner heat-affected zone in the substrate material and lower and better controlled inner residual stress and related deformation. In comparison with thermal sprayed coatings, it can offer the metallurgical bonding to the substrate and fully dense coating microstructure with zero porosity, enabling the full corrosion protection of substrate. The range of materials deposited by laser cladding is limited to metals and its alloy due to the principle of technology, requiring the simultaneous melting of substrate surface layer and added coating materials. To improve the wear resistance, the hard particles such as carbides are added to the feedstock powder. During deposition process, the kinetics of melting and solidification of both metal and carbide particles are controlled by used technological parameters of laser. In the paper, the influence of deposition parameters on the microstructure of WC-NiCrBSi laser clad coating is presented with attention paid namely to the rate of hard particles decomposition and its influence on the measured hardness.

Every year, around 300 million m3 of seawater is desalinated & lots of researches are involved in the same domain. Various methods & techniques were invented to rise up the level of water purity. One of the largest used techniques in this domain is the Reverse Osmosis, which is a simulation to the natural phenomena called Osmosis that depends on high pressure pumping of the conducted seawater to the RO modules, in order to desalinate the water from salt.
However, obstacles were always facing researchers during the realization & also preventing the device from damage while facing the immense seawater pressure (50 to 62 bars). But the worst obstacle is corrosion problem! Due to the high salt concentration in the seawater, what did extend the challenge to find more solutions to increase the yield & decrease the energy consumption with assuring a long-life for desalination device.
In 1992, Energy Recovery, Inc.(ERI) was established and manufactured ultra-high efficiency recovery products and technology, specifically the ERI Pressure Exchanger (PX) that is among the enabling technologies driving the rapid growth in seawater reverse osmosis (SWRO) using the alumina Al2O3 , known with a thick oxide layer that protects the metal from oxidation.
For the first time, a predicted design of the ERI pressure exchanger’s geometry was built, analyzed & verified with a numerical simulation to show the long life time of the ERI PX (up to 20 years & more) & explain the strength, high pressure & corrosion resistance of its forming materials.

The paper presents a comparative tribological study of zinc coatings in dry friction conditions in the context of the evaluation of their wear intensity. For this purpose a three zinc coatings: hot-dip, galvanic and lamella were imposed on steel screws type M16×50 – 160 typically used in the automotive industry. The tests were conducted using a tester T-11. As a result of tribological tests the friction coefficient of investigated coatings was determined. In addition, an analysis of the microscopic changes in the surface was made in order to identify the wear mechanisms and also measurements of the surface texture were compared. Based on the investigation results we found that the kind of coating influence essentially the tribological properties of the coatings tested in dry friction conditions.

The reliable performance of 12Kh18N10T steel articles to a large extent is determined by the quality of their surface layer formed during surface treatments.
One of methods of the surface processing of articles is a vacuum ion-plasma treatment, technological possibilities of which allow one to substantially change the properties of surface layer under the action of gas-metallic plasma streams. The range of applied energies and element composition of streams change significantly the initial state of article surface at the expense of both changes in the chemical composition of surface layers and occurred physico-chemical and phase transformations.
The present work is devoted to the study of technological action of accelerated gas-metallic plasma streams on a treated surface. Changes in the properties of the surface and near-surface layer of the 12Kh18N10T steel assure the creation of surface layers characterized by the high hardness and wear-resistance at the expense of enrichment of the surface with light elements, such as hydrogen, nitrogen, carbon and formation of their solid solutions and compounds. We studied changes in the reduced surface potential that characterizes changes in the energy state of the sample surface subjected to the treatment with various gas-plasma streams. The performed quantitative layer-by-layer analysis of the chemical composition of surface layer of the 12Kh18N10T steel showed changes in its chemical and phase compositions. The effect of the sign and magnitude of reference voltage at the treated sample on the properties of surface processed with the plasma has been studied. It was shown that the processing of steel with an electron argon gas-plasma stream leads to an increase in the chromium concentration in the surface layer and to a decrease in the iron concentration in the surface layer 0.1 micrometers in thickness. The treatment of the steel surface with ion argon gas-plasma leads to the increase in the iron and carbon concentrations within the same depth ranges, which favors the increase in the hardness of sample surface.

Hard chromium plating is produced by electrodeposition from a solution containing chromic acid and a catalytic anion in proper proportion. The metal produced is extremely hard and corrosion resistant. The process is used for applications where excellent wear and/or corrosion resistance is required.
In this study, which was carried out in collaboration with Robert Bosch Gasoline Systems, determination and solution of white spot defects on Bosch's high-pressure solenoid injector HDEV5 were aimed. Formation of white spots (or white patches) reduces the coating thickness resulting in lower hardness and poor abrasion resistance. In order to eliminate the formation of white spots; anode changing times were optimized, thickness of Pt coating on anode was increased, electrolyte flow rate was optimized, chemical properties of plating bath was examined (pH, concentration, etc.) and finally cleanliness (particle in bath), age and quality of bath were optimized. The results have shown that the formation of hydrogen and particle content (cleanliness) was responsible for white spot formation.

This study examines the relation between surface condition and its response to interaction with a laser. The surface character is modified by the creation of oxide layer. The oxide layers were created by solid state pulsed laser that is mostly used for industrial marking. The relation was tested on samples with a different width of created oxide layer. The modified samples were processed by diode laser used for surface treatment (mostly hardening). The surface temperature was measured during this experiment. The surface hardness and hardness depth profile was measured for all samples. The effect of pretreatment on hardness and microstructure will be discussed. The goal of the work is to find out optimal parameters for creation of the oxide layer that cause sufficient modification of optical properties to make the required laser absorption rise possible.

Shape memory polymers are a special type of polymer, which can recover the permanent shape upon the application of external stimulus. The main advantage of shape memory polymer is the ability of recovering a large amount of strain (usually >400%) in comparison to shape memory alloys (SMP) (up to 15%) and shape memory ceramics(2-3%). The material used in this research is Shape Memory Polymer due to its excellent shape recoverability. Before going into the details of the various topics of my work some of the basic features of SMP are discussed first. Thermoelectric phenomena provide the direct conversion of heat into electricity or electricity into heat, the phenomena are described by three related mechanisms: the Seebeck, Peltier and Thomson effects. The main objective is to realize pseudo-composite material: Unidirectional Carbon nFiber (UCnF) reinforced shape memory polymers-(SMPs) nanostrip multilayers material Vyborcntmat-SMP( VycnT). It is a challenge for new generation of turbochargers to limit diesel-cars exhaust hot and dangerous gases and protect life and the environment.

There is a persisting trend in automotive industry to increase safety of passengers while decreasing the cost and fuel consumption of the car. Usage of ultra and advanced high strength steels for manufacturing of car body parts is a way, how to achieve this goal. However, the manufacturing process of these parts requires presence of Al-Si coating on the surface of the steel. This coating is composed of multiple sublayers which are cause of various issues affecting the stability of welding process and strength of adhesive bonds between those parts. This paper investigates the possibility of homogenization of Al-Si layer by laser treatment in order to improve strength of welded and adhesive joints.

The paper deal with the corrosion of the inner surface of boiler pipes made of structural carbon steel L290NB that are part of the combustion chamber of the steam boiler with 10MPa operating pressure and in which the demineralized chemically treated boiler water circulates naturally along with the alkalizing solution of Na3PO4. The outer surface of evaporator piping is heated by combustion gas temperature up to 1200°C, which leads to the formation of saturated steam that changes in boiler superheater to output superheated steam in an amount of 200 t / h used for the production of electric energy.
The corrosive attack always occurs on the inner walls of evaporator piping, particularly in the areas of uneven and inhomogeneous surfaces and leakage of pipes, accompanied by leakage of process fluid into the combustion chamber of the boiler. Violation of the pipe integrity leads to the forced shutdown of the facilities producing superheated steam and electric energy.

Based on the results of experimental tests it was found that uneven dosing of alkalizing solution causes during the production of saturated steam an increase of the content of the monitored amount of P2O5, which remains in the boiler water together with the ions of copper released from brass and copper pipes of the boiler supporting device. Due to the presence of released copper ions, the corrosion mechanism of the inner walls of the pipes is influenced and accelerated. The results of empirical measurements show that the process of corrosion due to the heat load of the pipe material by combustion gas temperature up to 1600 °C is supported at the same time. Lowering of P2O5 content and Cu ions together with the heat load reduces the corrosion attack.