Process was developed for free-chromate passivation of zinc coatings. An optimal composition of the solution was developed. It was shown that titanium-oxide passivating coatings on the zinc-plated steel articles compare well in corrosion resistance and protecting capacity with iridescent chromate coatings. It was revealed that, unlike chromate coatings, the developed cerium and silicon-containing coatings withstand the thermal shock without degrading of characteristics.
The oxidation of metallic tantalum was monitored in an oven for X-rays with a graphite resistance under continuous vacuum or under controlled carbon monoxide pressure.
We demonstrate that this brought into play the formation for 2 varieties of Ta2O5 oxide, hemicarbide Ta2C and monocarbide TaC likely to be formed between 293K and 2288K, in accordance with a reaction mechanism which we found to take place over several stages. We determined the crystalline characteristics at high temperatures for all observed solid phases.
Particular importance is attached to the study of thermal expansion of carbides phases.
The article contains the experimental results of research on the use of vibratory machining with loose abrasive media. The aim of the study was to investigate the influence of vibratory machining time, with ceramic media, on geometric surface structure changes and deburring and rounding effect. In the study were used CB series ceramic media and ME L100 A22/NF was added as a liquid lubricant. The tests were made for a material made of a copper. The finishing was carried out on in a Rollwasch SMR-D25 vibratory tumbler. The surface of the finished objects was examined with a Nikon MA200 microscope equipped with a NIS-elements viewer (version 4.20). The surface texture of the finished elements was examined using a Taylor Hobson Talysurf CCI Lite optical 3D profiler. The effect of processing time on mass loss, mean changes in arithmetic surface roughness, Sa were determined.
By welding using Plasma transferred arc (PTA) hardfacing, Ti-SiC and Ti-B4C ceramics were prepared to titanium alloy mats. Titanium alloys were initially coated with TiB2 by diffusion boriding in boron backfill, with a thickness of up to 100 μm, in order to achieve an intermediate layer with a lower expansion coefficient. On these layers, cermets, made from a mixture of elemental Ti and hexagonal SiC in different stoichiometric ratios, were deposited by plasma welding technique. Despite the relatively short heating time, it was in the rtg. analysis of tetrahedral TiSi2. Similarly, boride sheets with a Ti-B4C cermet coating were prepared and an optimal stoichiometric composition was obtained to achieve a maximum TiB2 content of high hardness of up to HV 22 - 29 GPa. The prepared samples were subjected to the anti-ballistic resistance test against the special 38 caliber projectiles.
The most restrictive property of ceramic thin films for a variety of applications is their limited fracture toughness. Recently, the authors have uncovered that the arrangement of ultra-thin and heterogeneous layers of transition metal nitrides (TMN) in a nano-laminated architecture has the potential to enhance the fracture toughness in comparison with their monolithic constituents.
Based on semi-empirical toughness criteria (Pugh, Pettifor, Greaves), we identified TiN/WN superlattice films as a particularly promising system. Density Functional Theory (DFT) simulations were conducted to establish the expected crystal structure and lattice parameter of the superlattice films and their components. The cleavage fracture strength of TiN/WN superlattice films was calculated by atomistic modelling. To provide experimental evidence, we used reactive magnetron sputtering to synthesise TiN/WN superlattice films with bilayer periods ranging from 2.8 to 166.5 nm and a total film thickness of around 2 µm. Monolithic TiN and WN films were grown to obtain reference figures. The synthesis of pure single-phase fcc-WN layers was performed with special diligence, so as to avoid the appearance of other phases, which necessitated careful manipulation of the processing parameters. The films were characterised using X-ray diffraction, scanning electron microscopy, and nanoindentation. The intrinsic fracture toughness was derived from the ratio of hardness to Young’s modulus.
The experimental results, which demonstrate a dependence of the mechanical properties on the bilayer period, are discussed and related to the DFT findings. This study is embedded within a larger project, which aspires to reveal the impact of the difference in structural and mechanical properties between the involved TMNs on the manifestation and extent of the toughness enhancement in TMN superlattices.
The wear problems in the industry represent a very important role in the exploitation and functionality of most products. Wear of machine components and machinery results in huge industrial faults, various types of damages and even severe accidents. There are numbers of different types of wear and each requires a different practical approach to wear reduction, therefore wear is one of the costliest problems within the industry. Characteristic feature of abrasive wear process is the removal of material from the surface of components by a cutting action; in other words, the surface of a product is seriously damaged. This may be an intended and controlled process used in manufacturing of component, or it may occur accidently during exploitation. However, it is possible to avoid or minimise this effect by changing either design or materials of the product whilst reducing percentage of industrial wear. Furthermore, it is important to understand the mechanism by which damage occurs in any particular case.
The first challenge of the presented work was to solve industrial wear problems of chute for scattering of gravel of different fraction in the most economically efficient way. In this research the possibility to replace industrial wear plate by surfaced coatings using submerged arc welding technique and flux powder prepared from waste materials is presented. The main practical goal of this research was to find the right chemical composition of flux powder mixture in order to achieve high abrasive wear resistant surfaced coating of chute.
Researches about metallic pigments have been developed because of their properties of covering and anti-corrosion protection. Aluminum is a great material to manufacture metallic pigment due to the lamellar format of particles. The lamellar morphology increases the resistant of penetration creating a protection to the surface. The covering morphology of aluminum powder is known as “flake”. In addition, it is possible to recycle aluminum to produce pigment with high quality because of its capacity of recycling repeatedly. In this work will focus on the development of nanometallic pigment using aluminum scrap by high energy milling. The use of nanoparticles improves the ability of abrasion resistance, hardness and covering. The ideal morphology was reached by the control of milling parameter such as rotation and time. The flake was produced through of decrease of parameters in high energy mill. The development of the nanoparticles was obtained in planetary milling using alcohol 95% as additive. The additive was responsible to control the cold fusion in milling process. The material morphology and the size reduction in the different parameters of process were analyzed by Scanning Electron Microscopy (SEM). It was utilized to analyze Tescan microscope a VEGA 3 LMU model. X-ray fluorescence measurements were carried out in a Bruker S2 RANGER. The results indicate that the pigment was diluted in resin epoxy and applied in surface to check its adherence and homogeneity.
This paper deals with the influence of the EDM process parameters on the surface roughness of AlNiCo alloys. A BP 93L machine with an electronic generator was used to perform the machining. The workpiece was made of an AlNiCo alloy. Kerosene was used as a dielectric. During the EDM process, the parameters of current were changed. The impulse time and break time were also changed. The surface roughness and a 3D surface profile were measured. Roughness measurement was carried out using a Talysurf CCI Lite non contact 3D surface profiler. The analysis of the results was carried out with the Statistica 10 program.
The article presents the research results on acoustic emission (AE) generated by process of friction stir welding of sheets made of AW-5083 and AW-7020 aluminium alloys. Nowadays acoustic emission method is used in many fields of science, including in the diagnosis of machining and joining processes such as turning, grinding, milling, welding, etc.
Friction Stir Welding (FSW) – a new technology can be successfully used for butt welding of different types of aluminium alloy sheets. FSW method can be an alternative to traditional arc welding methods i.e. MIG or TIG. The joining process was carried out on laboratory stand built on the basis of universal milling machine FWA-31. Joining parameters chosen after optimization of the FSW process were presented.
The research was carried out on a laboratory test stand using an acoustic emission set made by Vallen System. This set included: 4 channel signal recorder AMSY 6, two measurement modules ASIP-2/S, preamplifier with a frequency range 20 kHz - 1 MHz and the strengthening of 34dB and AE signal measurement sensor type VS 150M, with a frequency range 100 - 450kHz. During the study, the acoustic emission (AE) generated by rotating tool and friction between joining materials and tool surface was recorded. The following parameters were determined: amplitude, number of events - hits, the effective value of the signal (RMS).
The study can be the basis for the use of acoustic emission method to monitor the process and determine the parameters of the friction stir welding for obtaining a high quality joint.
The possible effects on the protective performance of zinc-rich paints (ZRP) modified by combination of Zn dust with Al paste were investigated using electrochemical noise analysis (ENA). The role of two different Zn content was tested for two different ZRP formulations prepared with the same vol. % Zn:Al ratio as well as with the same binder and hardener types applied. The possible losses of protective performance of both ZRP were evaluated by means of EN measurements performed for tested coatings on steel substrate specimens during 168 hrs immersion test in 0.05 M NaCl. Due to supposed changes of cathodic nature of steel surface with immersion time ENA was used to provide information about possible delaminated corroduing area time development for tested coating/steel systems.
Thermal hardening of the surface layers improves the physico-mechanical properties of surfaces while these of the bulk remain unchanged. In practice induction hardening, flame, plasma and laser hardening are used, the latter two being widely used for hardening tool surfaces.
According to the literature, the application of, for example, intense plasma-arc treatment on the metal surfaces, in most cases causes partial or full melting. That, particularly in high carbon and high alloyed steels, leads to formation of large amounts of retained austenite with relatively low hardness, compared to the surfaces, hardened from solid state. The possibilities for reducing the retained austenite’s amounts are linked to several processes: cold treating, high-temperature tempering, deformation induced transformation.
A possible alternative to the energy sources, used for surface hardening, described above, is the hollow cathode arc. It represents a high-current, low-voltage electron beam with gas autofocus. By its nature, it occupies an intermediate position between the electron beam and the plasma arc. Hollow cathode arc is mainly used for welding, overlay welding, brazing. However, in the literature information about it uses for heat treatment and the possible results is missing.
In the present paper, the possibility for surface heat treatment of X210Cr12 steel with hollow cathode arc was investigated. The effect of the working parameters on some properties of the treated surfaces was established. The influence of the following heat treatment on the hardness and heat resistance was investigated.
The HDG coatings are subject of another processing before steel structure usage. The parameters of these processings may affect the adhesion of zinc layer. The paper presents some resulst of practical study of these parameters.
Zn-based alloys are widely used mainly as a protective coating in a corrosive environment but in specific applications they also need to comply with certain mechanical requirements. Research is usually focused on their corrosion resistance properties and less effort is devoted to study of mechanical properties, particularly to crack formation and propagation. Cracks can occur on the coating surface, at the interface to the substrate, or in specific phases of the coating.
The aim of this paper is to characterize the cracking behaviour of three types of Zn based galvanized coatings: Zn, Zn-Al and Zn-Al-Mg on a steel substrate before and after plastic deformation. This behaviour has been studied by observation of cracks occurred on the surface and on the longitudinal section after bending to various angles (0°, 5°, 10°, 15°, 30°, 60°, 90° and 180°). Metallographic sections were prepared by conventional metallographic procedures and cracks were observed by laser scanning confocal microscopy (LSCM) and scanning electron microscopy complemented with EDX analysis. Cracks on the surface were studied by light microscopy and LSCM.
Higher bending angles and more complex chemical composition lead to formation of higher number and density of cracks, especially in case of alloy system containing Mg. With higher bending angles cracks transformed from local interface and confined, or surface cracks to through cracks which exposed the steel substrate to the external environment. Coatings processed by uniform plastic deformation along with the steel substrate showed significantly improved cracking behaviour during bending.
Rare earth elements are widely used in metallurgy for alloying. It is known that small admixtures of these elements give unique properties to alloys. Rare earth oxides are used, for example, in optics or in solid-oxide fuel cells. In this work, the properties of electrodes based on oxides of titanium, ruthenium and rare earth oxides are investigated. The effect of organic additives on the surface properties of the electrode has also been studied. In the sample with butanol, the current density in the sodium chloride solution is almost 10 times higher than that of the electrodes without butanol. For the samples that showed the best results in electrochemical tests, the surface morphology was explored. The surface microphotographs demonstrate the cracks and the inclusions of rare earth oxides.
Magnetic resonance imaging (MRI) is one of the universal methods of modern diagnostics. Application of effective contrast agents in MRI enhances the quality, information content and to reduce the total time of patient examination. Innovative contrast agents exist in many types, one of them are magnetic nanoparticles based on iron oxides. The particles of iron oxides for practical use are modified by functional groups [1], because they have a high half-life and are actively absorbed by macrophages. Surface modification of the nanoparticles changes their structural and magnetic characteristics.
In this paper we studied the phase-structural state and magnetic properties of uncoated and coated cubic magnetite nanoparticles of dispersity from 10 to 30 nm. The functional coating was pluronic F-127. The cubic magnetite nanoparticles were obtained by the thermal decomposition method [2].
The morphology and size of hybrid nanoparticles were determined by transmission electron microscopy (TEM). The phase composition and average crystallite size were calculated by the Rietveld method [3]. Mössbauer spectroscopy was carried out in the transmission geometry at room temperature with a 57Co radiation source in a rhodium matrix. The spectra were processed using software package the Univem MS. The magnetic properties were measured on the vibrating sample magnetometer in fields up to 20 kOe and temperature from 5 to 300 K.
The results TEM studies of the nanoparticles confirmed the given morphology (more than 90% of the particles had a cubic form) and sizes (from 10 to 30 nm). Nanopowders are non-stoichiometric magnetite by the results of the
X-ray analysis. In addition, the X-ray spectra of hybrid nanoparticles have signs of the amorphous phase. Nanoparticles (core) are a superposition of bulk and surface «phases» non-stoichiometric magnetite. Correlation of magnetic and phase-structural characteristics is established for coated and uncoated nanoparticles. The evaluation of the change in the thickness of the surface «phase» is performed depending on the average particle size and the coating; REFERENCES: 1. Sosnovik DE, Nahrendorf M, Weissleder R. Basic Res Cardiol 103, 122-30 (2008); 2. H.T. Hai, H.T. Yang et al. Journal of Colloid and Interface Science 346, 37-42 (2010); 3. Rietveld H. M. Journal of Applied Crystallography, 2, 65-71 (1969).
The paper presents research on fractal analysis of martensitic steel X39Cr13 used for the manufacturing of surgical instruments. Fractal analysis was performed on samples subjected to sequential processes: annealing, surface treatment and sterilization. Annealed samples were tested towards corrosion resistance in physiological solution. Fractal analysis revealed that annealed samples were bifractal, whereas the remaining ones appeared monofractal. Hence, sterilization did not affect the surface morphology of the steel. On the other hand, after corrosion tests there were regular pits several hundreds of micrometers in diameter found in the annealed specimens.
The Hastelloy C-276 is commercially used representative of Ni-based superalloys family which is widely applied due to good corrosion and wear resistance. In this work the HVOF sprayed and post heat treated coatings of Hastelloy C-276 are studied. Heat treatment for 116h at 600°C in furnace and laser remelting with different parameters was carried out in order to reach different thickness of laser remelted coatings. Erosion test and linearly oscillating ball on flat test were applied to evaluate tribological behavior of HVOF sprayed Hastelloy C-276 coating. Microstructure of as sprayed and heat treated coatings were also studied. XRD and SEM analyses of wear tracks were applied to reveal the dominant wear mechanism. The tribological evaluation revealed the positive effect of heat treatment and especially of laser remelting on wear rate which was accompanied by microhardness decrease.
The structure and lattice parameters of the tantalum and tantalum oxides phases were determined by temperature X-ray diffraction under vacuum and low pressure carbon monoxide between 293 and 2278K. We show that the metallic phase structure is stabilized by inclusion of oxygen into the metal octahedral hole. We determined the crystalline characteristics at high temperatures for Ta and Ta2O5 phases.
Since, it is very difficult to form Ni-P deposit by electroless process on austenitic stainless steel as substrate, the activation with a weak acid etch, i.e., nickel strike should be applied. In this work a new method for Ni-P depositing on austenitic stainless by electroless processing is developed. In this way was avoided nickel strike pre-coating treatment which makes Ni-P coating process on stainless steel more complicated in comparison to other similar electroless processes on other types of steel, aluminium alloys, and so on. Study has been focused on influence of new activation process on adhesivity, microhardness and microstructure analysis of electroless Ni-P coatings. Adhesivity was estimated by Vickers indenter. Microhardness was tested by using scanning electron microscope. Microstructure of the electroless treated specimens was analyzed by optical and scanning electron microscopy. Based on experimental results, it can be concluded that by new method of activation of surface, electroless nickel - phosphorous coatings on austenitic stainless steel have higher adhesivity and microhardness than non-activated electroless nickel - phosphorous coatings.
Self-propelled rotary turning tools and actively driven rotary tools are characterized by different chip formation and different conditions of surface layer. Chips creating after conventional machining is influenced by specific patterns and can be affected by the machining scheme as well as the tool durability. This is a possible replacement for the coating effect of tool functional surfaces. The paper is focused on the issue of the state of surface layers after the application of the unconventional turning scheme. The state of the surface layers is evaluated by X-ray diffraction.
New approaches in the metrology field are required both in the direct metrology issues and in the area of calibration of the imaging tools (e.g. microscopes and image recording devices). This paper deals with the recent advances in preparation of dimension calibration specimens, primarily in the visible light optical area. These specimens are usually composed of supporting substrate (glass, quartz, silicon) covered by a appropriate metallic layer where the required scales and patterns are prepared using some of the suitable lithography technique. Alternatively, the bearing substrate may also be metallic and the scale marks might be prepared as engraved notches or structures layer of a different material. Photolithography enables the primary masters to be reproduced in a relatively cheap way, however their precision and pattern flexibility is limited. On the other hand, the electron-beam lithography being considerably more expensive, it still enables high resolution, high metric precision (which is usually derived from the laser interferometry) and the interesting custom patterning flexibility. Calibration samples dedicated to adjustment of scanning electron microscopes able to study metallic surfaces is of particular interest. Combined calibrating samples may put together custom required set of various patterns, including e.g. linear and circular scales and rulers in the micron and sub-micron region, concentric squares, rectangles and circles, large variety of linear and crossed gratings, customized patterns etc.
The hybrid coatings prepared on aluminum substrates were the object of a study of their tribological properties. An amorphous oxide layers Al2O3 were obtained on aluminum alloy EN AW 5251. The top coatings were sol-gel matrices with embedded nanoparticles of inorganic fullerene-like tungsten disulfide IF-WS2. The coatings were coupled with two kinds of plastic TG15 and PEEK/BG in order to measure their tribological properties as wear intensity and friction coefficient. Scanning electron microscope and surface topography with computer analysis were also studied.
This article deals with using the method of process FMEA in welding processes with the aim to eliminate the causes of defects in welded joints. The welded products and their welds require improvement in quality, both visual and structural. By increasing the quality of welded joints, we will achieve customer satisfaction and help to reduce costs in terms of forced repairs of non-conforming pieces. The welding quality is based on the weld joint requirements. It is always based on the business contract, the order and the relevant standards or technical conditions. The weld must be inspected and evaluated both on the surface and under the surface. Defects in welds are dangerous concentrators of tension that badly affect the limit of fatigue. The application of the process FMEA method aims to minimize defects in the welded joints and improve the resulting quality of the welded parts in the welded joints. To use this method properly, it is important to describe the welding processes, analyse the possibilities of defects and their consequences.
Hard particles used in combination with iron-based matrix are applied in a wide range of areas. It is used for screw conveyors, de-baler knives or mining gear teeth. The weld deposits can be used both in the production of these machine parts and in their later repair to increase their service life. The paper deals with the analysis of microstructures produced in the weld deposits combining martensitic matrix and 1-2 mm tungsten carbide particles. The investigated weld deposit was performed by welding technology using filled electrode Megafil A864M in a mixed gas atmosphere (Ar + N). Tungsten carbide particles were added due the vibratory feeder. Steel S690QL was used as a parent material.
The research focuses mainly on the microstructure analysis by electron microscopy (SEM) and the investigation of individual phases by diffraction analysis XRD. Using point chemical analysis, the movement of individual chemical elements between the base material, the weld deposit and the tungsten carbide particles was examined. Part of this paper is focused also on SEM investigation of worn surface of the weld deposit.
The authors paper attempt to identify parameters for laser padding technology. The coating material was prepared as paste made of Al2O3 powder and the coated specimens were made of spring steel. Laser coated specimens were subjected to tribological tests of abrasion resistance, hardness, microstructure and elements distribution in coat. The studies show that laser powder coating technology is possible. The selection of laser processing parameters determine properties of obtained coatings. It has been established that the obtained Al2O3 coatings significantly increases durability and resistance of tested components.
The article presents the research results referring to the analysis of the influence of cutting parameters on surface roughness parameter of marine pump shaft. The turning process was carried out on a universal CDS6250BX-1000 centre lathe. The research were performed on a shaft made of X5CrNi18-10 (AISI 304L) stainless steel. During lathing process used DKM 2010 turning dynamometer. The finishing turning process was carried out by cutting tool with CCET09T302R-MF removable insert by DIJET. During turning the following machining parameters were used: cutting speed Vc = 226 m/min, feed f = 0.044; 0.062; 0.083; 0.106 mm/rev and cutting depth ap = 0.25; 0.375; 0.5; 0.625; 0.75; 0.875; 1.0 mm. The goal of the paper was to define the influence of treatment conditions on cutting forces and temperature. Chemical composition of steel was measured by Solaris-ccd plus optical spectrometer.
Corrosion of reinforcing steel is one of the main reasons of reinforced concrete structures deterioration, which is caused primarily by chlorides. Electrochemical chloride extraction (ECE) and electrochemical injection of corrosion inhibitor (EICI) are promising techniques eliminating this adverse effect. Both the techniques are based on application of electric field. Electrochemical chloride extraction from a reinforced concrete structure may be accompanied with an electrochemical injection of healing agents if such agents are positively charged and are able to migrate towards the activated reinforcement. The right choice can be positive charge carried by cationic corrosion inhibitors. Tests have been applied on real samples of concrete with various corrosion inhibitors using diffusion or migration methods. After the corrosion inhibitor application, the migration ability of the individual inhibitors was monitored. Comparison of migration ability of inhibitors was based on concentration profile in various depths. In addition to migration, corrosion inhibitors have been tested for sufficient corrosion inhibition efficiency that was studied in chloride containing concrete pore solution.
Planar micro structuring of thin metallic layers allows to achieve required surface properties of metallic layers covering bulk materials. Recently, the arrangement of micro holes or pillars placed around the primary spiral according to a phyllotactic model was presented. This deterministically aperiodic planar arrangement was used for benchmarking purposes of the e-beam writer patterning. This arrangement based on single primary spiral and a variety of derived secondary spirals has several interesting properties. One of them is a very low ratio between the area populated by individual micro elements and the length of the primary phyllotactic spiral. This paper presents analysis of the phyllotactic spiral length and the rising gradient at the spiral outer edge. The practical part of the presented work deals with the patterning of a thin silver layer deposited on the silicon or glass substrates using e-beam pattern generation, lithography techniques and related technologies. An interesting impact of the mentioned spiral properties on the e-beam writing strategies and the exposure ordering strategy are also discussed.
Surface layers enriched with Al and Si were fabricated on an AZ91D substrate using thermochemical treatment in solid media. The AZ91D specimens were heated in Al+Si powder mixtures acting as a source of diffusion elements. Two temperatures were applied: 430 oC and 445 oC. The microstructural characterization of the layers was performed using an optical microscope and a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer (EDS). The layer produced at 430 oC had a thickness of 50 µm; the structure was composed of intermetallic Mg17Al12 and Al3Mg phases and Mg2Si phase. When a higher temperature (445 oC) was used, the layer was much thicker (600 µm) and the structure was predominantly a eutectic (an Mg17Al12 intermetallic phase + a solid solution of Al in Mg) with agglomerates of Mg2Si phase particles distributed over the eutectic matrix.
The set of five bronze vessels from the Late Bronze Age was found near to the Lidice village in 2014. The copper (I) chloride - nantokite was identified in a mixture of corrosion products. Nantokite is exposed to the surrounding atmosphere after excavation of the bronze vessels from a soil. Nantokite reacts with moisture and oxygen in the air to form copper (II) chloride hydroxide. Copper (II) chloride hydroxide has a larger volume than nantokite. The volume change of corrosion products leads to disintegration of metal core along the grain boundaries. Such a type of bronze corrosion damage is called bronze disease. The aim of the study was to suggest preservation coating system with the lowest oxygen permeability. The acrylic based lacquers (Paraloid B72 and Paraloid B48N), waxes (beeswax and microcrystalline wax) and corrosion inhibitor 1,2,3-Benzotriazole (BTA) were tested. Efficiency of monolayer and double layer preservation systems was compared. The double layer preservation system has performed the lowest oxygen permeability compared with the other tested substances. The inner layer is formed of the acrylic lacquer Paraloid B48N with addition of BTA and an outer layer is made of the microcrystalline wax with BTA addition. ACKNOWLEDGEMENT: Financial support from specific university research (MSMT No 20-SVV/2018).
Thermal spraying technology today belongs to manufacturing technologies that significantly reduce production costs while achieving high utility performance. The paper focuses on the methodology of testing of selected technological tests, especially bending and twist tests, metallography and porosity analysis of layers made by HVOF technology. The above tests are used by standard for the quality control during production. Proper implementation and evaluation are key to detecting possible imperfections during production and the possibility of repairs. Sprayings samples was based on WC-Co, WC-CrC, Stellit 6 made by HVOF technology on JP 5000, JP 8000 equipment’s.
This paper aim to be considered a review of the own researches realized in the non-conventional treatments domain in the magnetic field. The magnetic field applied under certain conditions during the cooling process of the steel samples in the case of the improvement treatments, modifies the mechanical properties of the steel.
It is important to take in consideration the improvement of the mechanical properties of a Cr-Mo alloyed steel used for the construction of the industrial machines parts. In this case, the influence of the magnetic field applied during the improvement treatment on the mechanical properties was considered. A thermo-chemical treatment in plasma completed the treatment program. The structural changes in the superficial layers during the treatment determine the improvement of the mechanical properties of the steel tested during the wear process.
The tribomodels behavior during the dry friction processes was analyzed. This study determines the wear intensity for a certain type of tribomodel and for a certain type of material. An Amsler stand was used. The rollers with different diameters were used in order to obtain different sliding degrees (ξ) and two distinct values of task of loading (Q) were considered.
The carbon steel is very widely used as a construction material in man industries. The corrosion of steel surfaces, especially in acidic solutions, contributes to large costs. The estimation of a corrosion rate and its reduction are problems of the great importance. Potentiodynamic polarization curves, obtained from a charge transfer controlled reaction, are used to designate the corrosion potential Ecorr and corrosion current density jcorr. The one of the most popular DC techniques for the estimation of the corrosion rate is an extrapolation of linear Tafel lines. These lines are a specific combined linear regressions derived from non-linear potentiodynamic polarization curves.
This paper describes a case study provided for the following problem: working electrodes made from C45 steel with specific coatings (WC-Co, WC-Co-Al2O3 and a reference without coatings) were investigated on the corrosion rate using the automatized potentiostat/galvanostat with combined software (PGSTAT 128N, AutoLab, Netherlands). The use of this laboratory stand resulted in the raw dataset of curves and the set of Tafel’s parameters, but without specific uncertainties. Therefore, a Monte Carlo based non-parametric approach was used to obtain a quantitative estimation of these uncertainties. The procedure, its results and discussion are described in the paper.
This work is focused on developement of a method for production of artificial copper patina pigment based on brochantite. A suitable titration method for this type was chosen to add sodium hydroxide to cupric sulphate. Following parameters were studied: solutions concentrations, ferric ion addition, dosing rate of titration, stirring intensity. Produced pigment was studied by means of XRD (phase composition), spectrophotometry (color) and SEM (morphology). In the first stage the suitability of this method was verified in small portions when the volume of cupric sulphate solution was less than 100 ml. In these experiments, the suitability of the method was confirmed both for pure copper sulphate and cupric sulphate solution with the addition of ferrous sulfate heptahydrate, which provide color closer to natural patina. After successful confirmation of the suitability of this method, it was passed to the second stage when this procedure was tested at large doses, the volume of cupric sulphate being 5 liters. This process is still improving. The first results indicate that this procedure is applicable to a pure copper sulfate solution, but not to a mixture of copper sulphate and iron sulfate. At the same time, immobilisation of these pigments by different types of varnishes following by long-term outdoor exposures were carried out to test the stability of the deposited layer on the sheets in a real environment.
The work devotes to study of hydrogen and deuterium storage and research of capturing hydro-gen and deuterium in tungsten samples irradiated with plasma beam. The paper shows that some changes occur in the surface like relief propagation caused by heterogeneous surface etching after ir-radiation with hydrogen plasma. Ratio of change in relief and structure of irradiated samples’ surface layer herewith depends on the irradiation temperature. Hydrogen and deuterium storage in tungsten have been studied while their irradiation with hydrogen and deuterium plasma. Thermo-desorption analysis of tungsten samples irradiated with hydrogen and deuterium plasma at 1000 °С degrees showed that tungsten surface became saturated with deuterium and did not become saturated with hy-drogen. The data obtained by emission spectrometry and thermo-desorption spectrometry verified, that the basic share of captured deuterium is accumulated at the depth of up to 7 µm.
At present, reinforced concrete or steel sheets with glass enamel are used for the construction of bioreactors, fermentation and storage tanks of biogas stations. To a lesser extent, corrosion-resistant steels are used and, in smaller dimensions, also plastics or fiberglass. Against leakage and corrosion due to biomass and biogas, reinforced concrete is mostly protected by bituminous coatings. Steel components are most often protected against corrosion by epoxy resins and cements. On the market there are modern plastic-based coating materials with high chemical and mechanical resistance, which can be applied to biogas stations to certain product dimensions. An initial study on the applicability of low-permeable ETFE ultra+ and PFA ultra+ hydrophobic anti-adhesion coatings of 700-1000 μm for steel components under anaerobic conditions exposed to corrosive effects of biomass and biogas was performed. Laboratory simulated conditions corresponding to the anaerobic bioreactor at 40 °C ± 1 °C included 2 months of incubation of the sample in biomass-based alkaline medium from the 1st fermentation stage of the agricultural biogas plant and then 3 months of incubation in acidic medium based on bio-waste mixture. While a structural steel samples lost a significant portion of their mass in the biomass contact area and also in the biogas contact area, the stainless steel samples exhibited intergranular corrosion under the microscope, and the ETFE and PFA coated samples did not change color or roughness, did not swell and no other change was visible. The corrosion test in salt fog according to ČSN EN ISO 9227 has confirmed a high service life (over 15 years) for both coating materials and very aggressive atmospheres. Both coatings are resistant against rusting, blistering, cracking and chalking. At 20 °C, both coatings were not visibly degraded even after 3 months of immersion in aqua regia, concentrated H2SO4 or concentrated KOH solution. The tested coatings are found to be suitable for the protection of steel surfaces in contact with fresh acidic biomass entering the bioreactor, in contact with the alkaline slurry or sludge in the bioreactor and in contact with the raw biogas.
This article presents the results of studying the structural-phase state changes of Ti-Al coatings on the surface of titanium synthesized by mechanical alloying. The study of the substrate-coating bound-ary showed the practical absence of traces of diffusion of the coatings in the titanium substrate after the mechanical alloying process. The mechanism of formation of Ti-Al coatings is due to cold welding and due to deformation compaction of powder particles on the surface of titanium under the impact of ball hits. Stirring of coating components with the formation of diffusion zones at the interfaces is ob-served after annealing at 600 ºC. Al3Ti is the first phase that forms in the coatings as a result of the interaction of Ti and Al. The compounds Al2Ti and TiAl are formed as a result of subsequent reactions between Ti and Al3Ti. After the process of mechanical alloying, heat treatment should be used as a complex treatment to accelerate the diffusion processes in the coating-substrate system.
The article describes a new method of applying titanium coatings on ceramic surfaces using special tools - rotating brushes with titanium fibers. The soldering of ceramic-metal joints involves the use of expensive active solder eliminating the lack of wettability of the ceramic. More economically advantageous solution is to give a wettability to the ceramic surface, by applying a durable titanium coating and using a wider range of soldering materials. The titanium coating obtained by means of friction metallization can be used as an alternative to metallization, for example by thermal spraying methods. The metallization method using rotating brushes enables the titanium coating to be applied on flat and 3D surfaces. The article outline the structure of the tool and the method of applying the coating, as well as the results of the tests carried out.
The paper presents the possibility of using the ImageJ computer program for image analysis as a method of assessing the proportion of sample surfaces occupied by corrosion. The program allows to calculate the size of any graphic selection and calculates the number of pixels contained in it, can also measure distances and angles between points or elements of images. The study used a sample made of steel 23MnB4. After preparing the surface, the samples were divided into three groups, which were then subjected to galvanic, hot-dip and lamela process. After the galvanizing, metallographic examinations were carried out during which the thickness and structure of the applied layer were assessed, and then corrosion tests were carried out in a salt chamber. The final stage of the research was a computer analysis of the image of the sample surfaces to be tested. For this purpose, the ImageJ program was used. The evaluation of the corrosion process using computer image analysis proves that such an assessment is more accurate than the method recommended by standards or comparison with standards and can serve, in addition to traditional measurements, to quantify the corrosion rate in a salt chamber. The unquestionable advantages of the program are its free availability, the possibility of expanding its own extensions and cooperation with any operating system.
This paper presents the results of investigation considering the morphology of surface layers produced by electro-spark deposition (ESD). It is a pulsed micro-welding process used for small scale and precision repair of high value worn or misfabricated components.The consumable electrode material is deposited onto the work piece by means of electric sparks in a manner reverse to spark erosion. In the electro-spark deposition process, the electrode is the anode and the work piece is the cathode. It has been found that the surface layer produced by ESD has good criteria resistance by changing the process parameters and promising protective properties. In the experiment, the coatings were electro-spark deposited with using an Alloy 400 electrode (the anode) - onto samples made of CuZN30 Bras (the cathode). The morphology of the layers is shown in the OM and SEM photomicrographs. As a result of the electric discharge, diffusion of individual elements was observed. For diffusion observations, ESD analyzes were performed on the cross-section of the produced layer. Microhardness measurements were also carried out.
Research conducted in many scientific centres on the operational properties of machine parts has shown that one of the critical components affecting the fatigue strength of parts is the condition of the surface integrity of their ingredients. In the case of elements produced by electrical discharge machining, the processes occurring during removal of the material: thermal and chemical, constitute the surface layer with different properties to the bulk material. In the paper presents results of experimental investigation of influence EDM process parameters on surface layers properties. The research was conducted using graphite electrode with varying discharge current, pulse duration, pulse interval. Furthermore, the mathematical model was established to estimate the influence of EDM parameters on surface roughness.
In the presented paper the subject related to the heat treatment (HT) of hot-dip zinc coating was initiated. Authors assumed that in the future widely understood optimization of coating HT will results in both mechanical as well as functional properties improvement. Investigations were focused on the hot-dip zinc coating deposited at industrial conditions (acc. PN-EN ISO 10684) on the Fe-C alloys surface (steel and cast iron). In the paper beside basic information: microhardness measurements, optical microscopic observation also examples of EDS after HT are enclosed. It was stated that although the applied HT results in coating hardness increase, the too high temperature level may cause coating cracking and delamination. As the processing temperature increases, the coating structure changes - the iron content in individual Zn phases increases. Zinc coating deposited on cast iron is more inhomogeneous.
The induction hardening is a well-developed technology in many industrial applications, e.g. automotive, tool manufacturing, casting technology, sheet metal forming etc. The induction hardening is generally employed for a surface hardening because the current induced during this process is concentrated directly under the surface of the workpiece due to the “skin effect”. Recently, more and more companies are opting for induction-based hardening solutions because it is ideal for integrating into production lines. This technology is extremely energy-efficient, particularly when compared to wasteful methods such as furnace carburizing. Additionally, transportation times and costs are reduced in this method. The most popular application of induction heat treatment are hardening of steels and cast irons. Hardening of components made from steels may be done for the purpose of obtaining certain properties including - but not limited to - strength, fatigue and wear resistance. The microstructure of steel prior to heat treatment (also referred to as the initial structure or structure of the parent material) also has a significant effect on results of the heat treatment and required process parameters.
This paper present a methodology of revealing of a microstructure after the induction hardening and results of a microstructure observation of two selected steels treated with the induction hardening using microscopy techniques. These microstructures examinations provide information about a prediction of required properties.
During hot-dip galvanizing, from the moment of immersion the reaction between molten zinc and solid iron starts forming intermetallic phases. This diffusion controlled process is responsible for the final phase composition of zinc coating. Several samples were created by hot-dipping at various immersion times at T=723K (450°C). Dipping times were divided into two groups. Short term immersion intended for studying the early stages of phase nucleation and growth and a long term immersion assigned for observing the later phase change and quasi-equilibrium states. For characterization of present phases EDX was used to determine iron concentration through the alloy layer. After metallographic preparation each phase layer thickness was carefully measured all along with the total thickness of the alloy layer. Results of these measurements were compared with the latest literature findings. Keeping the same conditions of immersion and changing only the duration allowed us to estimate nucleation and growth kinetics of the layer forming process.
Microstructure evolution of Fe-6 wt% Si alloy after laser shock processing (LSP) are investigated in this paper. Laser shock waves were induced by a laser system operated with a wave-length of 1030 nm and 2-10 ns pulse width. The microstructures of LSP samples were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the structure and phases after laser shock processing exhibits changes produced by shock wave during LSP.
In this work, structure, phase composition, microhardness, Young’s modulus and hydrophilicity of titanium oxynitride TiNxOy, and pure and phosphorus ions implanted TiO2 coatings produced by metal plasma immersion ion implantation and deposition were investigated. To evaluate the correlation between the structure of the layers and their cytocompatibility, the influence of the surfaces on the behavior of osteoblast-like SaOS-2 cells was studied in vitro. The good mechanical properties and biocompatibility of titanium oxynitride TiN0.4O1.6 and P-implanted titanium oxide TiO2 without any toxic elements make these Ti-based layers interesting candidates for long-term studies in vivo.
To date, a large number of different alloys based on CoCr, Ti, stainless steel, etc. are used in medicine. However, metal implants are bioinert, despite the development of biodegradable magnesium-based alloys. In addition, because of their mechanical properties, only few numbers of alloys have come close to mechanical properties of the cortical part of human bone. These superelastic alloys are usually based on the Ti-Nb-Ta , Ti-Nb-Ta-Zr systems which have a high cost. It is advisable to apply bioactive coatings that would have the best resemblance to human bone in terms of chemical composition, physical properties and biological parameters.
In this paper, the physical and chemical properties of hydroxyapatite (HAP) coatings with the addition of ZnO, obtained by electrochemical deposition in an aqueous solution on a printed porous sample of 316L steel, were studied.
The HAP study was carried out by the methods of analysis as: scanning electron microscopy with the energy dispersive microanalysis system, transmission electron microscopy with EDAX analysis system.
The laser melting of the powdered 316L was carried out using the Mlab cusing R machine. The SLM process parameters were: laser power 90 W, a frequency 50 kHz, a scanning speed 500 mm/s, a spot size 100 μm, the oxygen content was less than 0.1%.
The Ca /P ratio of coating corresponds to the generally accepted parameters. In the study, it was found that HAP molecules are embedded in the crystal structure of ZnO and form a chemical bond with the substitution of the Ca atom.
Galvanizing is an application of a zinc coating on the steel base material by electrolytic deposition. Zn coating protects anodically the base material (typically unalloyed or low-alloy steel) against corrosion. In the final phase of the galvanic process the final finishing employing chromate coating (yellow or blue) is often used. The treatment causes the non-conductivity of the surface coating of the material.
Glow Discharge Optical Emission Spectroscopy (GDOES) measures correctly, accurately and with good repeatability the thickness and composition of the zinc coating without the non-conductive surface treatment (chromate). This paper aims to verify the possibilities of the optical emission spectrometry for the analysis of non-conducting surfaces. Optical microscopy is taken as the reference method for the measurement of layer thickness, because this method is generally accepted as an accurate and correct.
The article presents the method of developing parametric tables for the laser technology of surface micro-texturing. A method of evaluation of the impact of various combinations of selected process parameters, such as the scanning time and the length of the laser pulse train, on the material is presented. Experimental tests of the impact of the laser beam on the material were conducted using a laser device with ultra short pulses. A two-factor statistical analysis was carried out on the basis of a developed array of combinations of parameters and assessed effects of laser beam interaction. A mathematical model of the process in the form of a function of two variables, defining the influence of the indicated parameters on the process effect was developed. On the basis of derived dependence it is possible to estimate the impact of the laser beam on the material using any combination of processing parameters. The specific dependence can be used for proper selection of parameters in order to obtain the desired effects on the surface of the material. The tests and statistical analysis were performed for the selected metal material. The article ends with a discussion of the obtained results and the developed method.
The aim of the project is to develop a new hybrid photovoltaic cell with unique architecture consisting of ZnO structures. The cell’s architecture will guarantee at least 20% energy conversion effectiveness and enable production costs reduction of c.a. 30%.
R&D work will be based on a technology concept developed in Institute of Physics (IF PAN) which is patented. Its innovativeness lays in the use of ALD and hydrothermal (with microwave sources) methods to develop a completely unique architecture of cell allowing for improvement of its physio-chemical parameters, as well as elimination of few energy consuming production modules and reduction of critical elements from cell production process.
Presented the work has proven critical functions of the technology, that is the availability of ZnO layers deposition, incl. nanorods, as crucial part of cell’s architecture and their positive impact on cell’s effectiveness.
The article contains a description of the results obtained in the first hydrothermal test with the use of a new reactor, in which the previously used microwave heating has been replaced.
Due to the reduction in production costs, not only in the automotive industry, more and more sandwich-structure parts are emerging to replace expensive, technologically complex elements such as cooling rotors in electrical installations. They are required to meet a complex set of attributes – resistance to abrasive wear, anti-corrosion requirements, and especially manufacturing costs.
This article discusses and compares the mechanical properties of a critical part (cooling rotor) made as a sandwich structure of aluminum alloys and nickel-phosphorus (NiP) coatings.
The specific mechanical and corrosive properties of the thin NiP film vary with the percentage of phosphorus and the heat treatment. On the other hand there is the loss of mechanical properties of the aluminum alloy at the temperatures of the nickel-phosphorus cure.
The aim of this article is to find the appropriate mechanical properties of this sandwich-structure part in the view of changing mechanical properties of each of the sandwich components. To obtain these properties, indentation methods and finite element methods are used.
In recent years, the cerium-based conversion coatings have been increasingly used as one of the more promising chromate coatings substitutes on aluminum alloys, as cerium compound do not pose environmental problems and the coatings provide an efficient corrosion protection close to that of chromium. The cerium-based layer was prepared from simple immersion of aluminium alloy sheets in a solution composed of a 4-8 g•L-1 Ce(NO3)3•6H2O; 30-50 ml•L-1 H2O2 (37%) and 0.5-1,5 g•L-1 tannin at room temperature. After optimization of several parameters as deposition bath composition, immersion time, drying temperature and so on, the corrosion resistance was evaluated mainly by means of salt spray tests (SST). It was established that the thickness of cerium-containing coatings is about 280-320 nm.