Recently, some systematic studies have been conducted on microstructural changes and material properties of B2 FeAl coatings sprayed by supersonic stream metallization in HVOF (High Velocity Oxygen Fuel), HVAF (High Velocity Air Fuel) and DGS (Detonation Gas Spraying) conditions. The present paper reports the results and analysis of HVOF, HVAF and DGS supersonic spraying on the structure and properties of Fe-Al type coatings obtained from spraying the Fe40Al0.05Zr at. % +50 ppm B intermetallic feedstock powder on a C45 steel substrate. A comprehensive study of the coating performances was conducted in relation to their material parameters by taking into account technological conditions affecting the formation of a structure in the ultrasonic spraying technologies. Analysis included chemical-phase composition inheritance, morphology of the grains, and porosity as well as oxidation of the coating material, hardness and abrasive resistance. These properties were analysed to determine if, Fe-Al coatings could be used as a potential material in the elements of gas turbines and boilers. Key words: Fe-Al type coatings, HVOF, HVAF, and DGS ultrasonic spraying technologies.1. INTRODUCTION The FeAl and Fe3Al-based iron aluminides are of interest as potential materials for hot structural applications, and they are promising substitutes for stainless steel and cast iron at room temperature, both as bulk materials and as coatings [1, 2]. Their promise is due to their good mechanical properties, relatively low density (5.56 g/ cm3 for the FeAl phase), excellent corrosion resistance in oxidizing and sulfurizing atmospheres (a result of their ability to form a highly protective Al2O3 scale), and low manufacturing cost [2, 3]. However, their use as bulk materials has been limited by their brittleness at room temperature and poor creep resistance [4]. The implementation of the Fe-Al type intermetallics as protective coatings can reduce these drawbacks. A więcej »
 

The work presents research results of impact of Nb, Ti and V microadditions on recrystallization kinetics and microstructure of newly elaborated steels assigned for production of forged machine parts, using the method of thermomechanical treatment. The study was performed with the use of Gleeble 3800 simulator. In order to determine recrystallization kinetics of plastically deformed austenite, discontinuous compression tests of specimens were done with a given strain at the rate of 10 s-1, in a temperature range from 900 to 1100°C, with isothermal holding of samples between successive stages of deformation for 2 to 100 s. Recrystallization kinetics of plastically deformed austenite was described using the Johnson-Mehl-Avrami equation. Performed two-stages compression tests revealed that microadditions introduced into steel considerably influence the kinetics of static recrystallization. Determined time of total recrystallization of austenite, tR, in a temperature range from 1100°C to 900°C changes from 100 to 600 s and from 300 to 800 s — for the Ti-V steel and Ti-Nb-V steel, respectively. Executed hot compression tests will contribute to establishing conditions of forging with the method of thermomechanical treatment. Key words: HSLA steels, thermomechanical treatment, static recrystallization.1. INTRODUCTION HSLA-type (High Strength Low Alloy) microalloyed steels — containing up to 0.3% C and 2% Mn and microadditions with high chemical affinity to N and C, i.e. Nb, Ti and V in the amount of about 0.1%, and sometimes also slightly increased concentration of N and up to 0.005% of B, increasing hardenability — are particularly useful for production of forged parts with fine-grained microstructure using the method of thermomechanical processing. The interaction of microadditions in steel in a solid state depends on their state under conditions of performed plastic working. Microadditions dissolved in a solid solution rais więcej »
 

Allvac 718Plus (718Plus) is a high strength, corrosion resistant commercial polycrystalline nickel-based superalloy developed by ATI ALLVAC over 10 years ago. 718Plus has been designed to fuse the most desired properties of Inconel 718 and Waspaloy, producing advantages of good mechanical properties, higher working temperature than Inconel 718, good fabricability and reasonable cost of production. 718Plus is strengthened by γʹ phase and other precipitates which are located mainly at grains boundaries. Compared to Inconel 718, 718Plus has increased concentration of Al, Ti and Co and decreased amount of Fe. Weldability of 718Plus is comparable to Inconel 718, thus there is a risk of intergranular microcracking in heat affected zone (HAZ). The test joint have been welded autogenously using electron beam at 120 kV accelerating voltage, 10 mA current and 78 cm/min welding speed. The microstructure of casted base material, heat affected zone (HAZ) and weld metal of electron beam welded 718Plus were investigated by means of light (LM) and scanning electron microscopy (SEM). SEM observations of welded joint microstructure were performed using secondary electrons (SEM-SE). SEM/EDS analysis were carried out. Both MC type carbides and Laves phase were observed in interdendritic regions of base material. The microstructure of heat affected zone was composed of γ matrix, γʹ phase and MC-type carbides, Laves phase and Laves/γ eutectic. In weld metal zone no γʹ precipitates were observed. The microhardness measurements have shown a decrease in weld metal and HAZ. It can be caused by an influence of the welding process thermal cycle. Key words: 718Plus, electron beam welding, SEM.1. INTRODUCTION Allvac 718Plus (718Plus) is a relatively recently developed nickelbased superalloy which properties lead to widespread potential of applications. This alloy belongs to a group of nickel-base superalloys strengthened by ordered więcej »
 

TiO2 coatings on 316L steel were obtained by use of electrophoretic deposition (EPD) method. Potential zeta of nc-TiO2 particles in suspensions containing water and ethanol in different ratios was measured. Suspensions’ pH was stabilized by addition of acetic or citric acid and ammonia solution. Addition of citric acid in small amount decreased the zeta potential. Optimal suspensions’ parameters for cathodophoretic and anodophoretic deposition were selected based on the results of zeta potential measurements versus pH for suspensions with different water-ethanol concentration. For the chosen suspensions the rate of TiO2 deposition was measured. Coatings’ cohesion was improved by sintering or addition of biopolymer (chitosan) into suspension. The microstructure of coatings was examined by scanning electron microscopy. The roughness and thickness of the coatings were measured by optical profilometer. The corrosion resistance in Ringer’s solution was examined by use of polarization curves. The corrosion resistance of coated steel was higher than that of uncoated one. For sintered coatings the corrosion currents were lower, but the passive area was larger for not sintered ones. The contact angle of the coatings was measured using a sitting drop method and superhydrophilic properties of TiO2 coatings were confirmed. Manufactured coatings may be potentially used as self-cleaning materials. Additionally, TiO2 coatings improve corrosion resistance of steel and exhibit good bactericidal properties. These characteristics may make this sort of materials potentially useful also for medical purposes. Key words: TiO2 coatings, electrophoretic deposition, 316L steel, zeta potential measurements, superhydrophilic coating.1. INTRODUCTION Stainless steel is commonly used in many areas, e.g. marine systems, nuclear, chemical, food, construction industries and biomedical purposes [1÷3]. A wide range of industrial applications is possible więcej »
 

Copper composite coatings with nanodiamond particles were electrochemically deposited. Depositions were made on copper sheet basis in acid sulphate solutions with and without organic additives. The studies indicate the possibility of electrochemical deposition of composite Cu/diamond coatings and the coating properties depend on solutions composition. The concentration of the diamond preparation in process electrolyte solutions was about 0.5 g/dm3. The composites surface morphology was investigated by SEM microscopy and chemical composition with EDS microanalysis. Concentrations of diamond particles in samples surfaces were evaluated by ImageJ computer analysis. Hardness of coatings were measured by Vicker’s method. Key words: composite coatings, copper/nanodiamond composites, electron microscopy, EDS analysis, hardness measurements.1. INTRODUCTION Metal matrix composites with incorporated disperse phases are intensively investigated. The research is aimed at the production of materials having improved mechanical, tribological, electrical, thermal, and other properties. An important area of application are power electronics devices. The evolution of devices in a miniaturization direction causes problem of heat dissipation of integrated circuits based on semiconductors commonly used, such as Si, SiC and GaAs, and new one like GaN [1]. New electronic devices would be implemented in telecommunications, aerospace, military equipment and other industries [2÷7]. Copper is attractive as a matrix material because of good electrical conductivity, but also very good mechanical properties, like plasticity. There are attempts to incorporate into Cu matrix additional phase of carbon particles, also like micro- and nanodimensional diamonds [8]. Advantageous properties for this kind of material is its large thermal conductivity and low thermal expansion coefficient. Diamond is also hardest known material. Obtaining a composite material with di więcej »
 

The purpose of this work was to investigate the influence of nanostructure on titanium corrosion resistance in physiological saline (0.9% NaCl). In order to obtain the nanostructure the titanium rod was processed through multiple hydrostatic extrusion (HE). Corrosion tests included electrochemical impedance (EIS) and potentiodynamic (PD) measurements. EIS tests were performed after 2 and 24 hours of immersion in 0.9% NaCl. Potentiodynamic measurements were carried out immediately after the last impedance test. Profilometric examination was used to check whether the samples were equally prepared for corrosion measurements. After corrosion tests a scanning electron microscope (SEM) was used to characterize the morphology of the surface. Corrosion tests revealed the positive influence of nanostructure on titanium corrosion resistance. Moreover, the differences observed were larger in the case of a shorter time of immersion in physiological saline. Hence, it might be surmised that the rate of the passivation process depends on titanium grain size. The microscopic characterization of the surfaces of samples after the corrosion test indicated differences in the surface morphology. The passive film formed on the nanocrystalline sample was more compact and homogenous than on the microcrystalline one. The different number of structural defects in micro- and nanocrystalline titanium might be the reason for the observed phenomena. Due to their higher energy, structural defects could be preferential sites for the nucleation of passive layers. Consequently, the rate of passivation should be higher for nanocrystalline materials. Furthermore, the high volume fraction of structural defects also explained the existence of more tight and uniform passive layer on the nanocrystalline titanium. Good corrosion resistance in physiological saline means that nanotitanium could be an attractive material for biomedical applications. Key words: corrosion, nanostructured więcej »
 

The object of this work was the self-passivated Ti-15 wt % Mo implant alloy subjected to anodic oxidation in 1 M acetic acid aqueous solution at 5 V for 1 h. In order to thicken the oxide film a superior biocompatibility and corrosion resistance of the anodized implant was achieved. Surface of the tested alloy before and after anodizing was characterized using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and profilometry. Electrochemical impedance spectroscopy (EIS) measurements revealed a passive behaviour of the alloy under the experimental conditions. The bilayer oxide film consists of a porous outer layer (6.7±1.0 nm) and a thin, solid inner-barrier layer (1.4±0.3 nm). The obtained film is three times thicker than the oxide layer formed by self-passivation. The electrochemical studies in physiological saline solution (PSS) at 37°C showed that the anodic oxidation improved the corrosion resistance of the Ti15Mo alloy. No pitting corrosion was detected in anodic polarization measurements up to 9.5 V due to the presence of the barrier oxide layer on the alloy surface and phase composition of the examined alloy which contained only β-Ti phase. Key words: Ti15Mo alloy, anodization, oxide layer, corrosion resistance, EIS.1. INTRODUCTION In recent years titanium and its alloys were found to be very popular biomaterials for medical applications due to their excellent mechanical properties, high biocompatibility and good corrosion resistance [1]. Nowadays, toxic metals present in medical titanium alloy are replaced by neutral and non-harmful ones for human body. Among these materials, Ti15Mo alloys can be some examples. Allergenic and carcinogenic elements such as Ni, Al and V have been replaced by a biocompatible molybdenum [2]. Addition of Mo increases the corrosion resistance simultaneously reducing the elastic modulus [3]. If the Mo content is higher than 10 więcej »
 

Intermetallic Ti-Al alloys are characterized by the unique set of properties which makes these alloys a prospective material for the energy, automotive and aviation industries. The mechanical properties of a intermetallic alloys are strictly related to the microstructure. The refinement of the microstructure can be obtained by the manufacturing process, alloying additions and heat treatment. Microstructure characterization and knowledge about phase transformation mechanisms and their temperature ranges allows to change properties of the bulk material. The aim of this study was the microstructure and phase composition characterization of intermetallic Ti48Al2Cr2Nb alloy. The microstructure was examined using the light and scanning electron microscopy. Identification of phases and their temperature stability were determined by X-ray diffraction, differential dilatometry and calorimetry investigation. The oxidation process was determined by high temperature X-ray diffraction and the thermogravimetric method. The alloy after annealing has a duplex microstructure with precipitations of α2 phase in the γ matrix. Dilatometry and calorimetry allowed us to define the stability of each phase. At first the enriched in chromium α2 phase dissolved, after that the regions depleted in chromium were transformed, and above 775°C the microstructure was only the γ phase. Gamma phase was transformed above 1100°C, the end of transformation γ → α was evaluated as 1250°C. The oxidation investigations allowed us to show that the oxidation process started at 700°C by the oxide layer formation, which was stable till 900°C. Above this temperature the oxide layer started to grow. Key words: intermetallic alloy, microstructure, phase composition, Ti48Al2Cr2Nb, titanium alloy.1. INTRODUCTION Titanium intermetallic alloys due to their unique properties could find possible applications in a wide range of the industries, especially when th więcej »
 

Nitriding is commonly used method of thermochemical treatment in order to produce surface layers of improved hardness and wear resistance. Using a gas nitriding with changeable nitriding potential, a nitrogen concentration at the surface could be controlled, influencing the phase composition and the growth kinetics of the layer. In this study, the hybrid surface treatment was applied. It consisted in gas nitriding and laser heat treatment (LHT) of 42CrMo4 steel. Two nitriding processes were carried out using changeable nitriding potential. Parameters on first process were as follows: temperature 570°C (843 K), time 4 h. The second process was performed at lower temperature 520°C (793 K) and longer duration 10 h. This resulted in various depths of the compound zone at the surface (20 and 8 μm, respectively). Next, the nitrided layers were laser heat-treated using TRUMPF TLF 2600 Turbo CO2 laser. Laser tracks were arranged as the single tracks with various scanning rates (vl = 2.88 m/min and vl = 3.84 m/min). The laser beam power (P) ranged from 0.26 to 0.91 kW. The effects of the depth of compound zone as well as LHT parameters on the microstructure, dimensions and microhardness of laser tracks were analysed. In the majority of the produced laser tracks, remelted (MZ) and heat-affected (HAZ) zones were easily identified. Different microstructure was visible at low laser beam power (0.26 kW). The dimensions of MZ were limited, whereas the HAZ was clearly observed. The compound zone was still visible at the surface. Only the porous ε nitrides were slightly melted. Hardness increased significantly after LHT with complete and partial remelting of compound zone. Laser beam power and scanning rate influenced the depth and width of MZ and HAZ, so the thickness of hardened zone. The greater laser beam power or the smaller scanning rate, the larger hardened zone was observed. Key words: gas nitriding, laser heat treatment, microstructure, hard więcej »
 

The following paper investigates two model alloys simulating the quenched matrix of high-speed steels with an addition of 1.5% Ni, which was enriched with 1% and 2% of Nb to increase abrasion resistance. Based on the alloys’ composition comprising of W, Mo, V and Cr, the simulations of the quenched matrix of the high-speed steels indicate sufficiently high hardenability. The purpose of increasing the nickel content in the composition of such alloys was to increase their crack resistance, whereas the addition of the strongly carbide-forming niobium in amounts of 1% and 2%, balanced by an additional carbon content, was aimed at increasing the abrasion resistance of these steels. The authors of the above mentioned chemical composition concept expect that these types of alloys will be used in the production of tools (rolls) designed for the rolling of metallurgical products which are difficult to produce (flat bars, channel bars and tee bars). The quenching temperature of both alloys was optimised on the base of the so called quenching series. The accurate CCT diagrams and the tempering series for revealing the secondary hardness effect were also performed for these alloys. All investigation stages were accurately documented by metallographic tests. Key words: metallic alloys, high-speed steel, phase transformations, dilatometric investigation, CCT diagrams.1. INTRODUCTION Intensive investigations of high-speed steels and their quenched matrix were carried out at the AGH in Krakow, during the 1970s [1]. The influence of the most important alloying additions to this steel group was determined by, among other things, the influence of the W/Mo ratio content on hardness, bending strength, crack resistance (by KIc method), prior austenite grain size, retained austenite fraction and tempering. The basic alloy of those investigations constituted the matrix of quenched steel HS6-5-2, whose chemical composition: 0.5% C, 2.0% W, 2.8÷3.0% Mo, 4.5÷ więcej »
 

The manufacturing of the erbium/ytterbium co-doped oxyfluoride glass-ceramics optical fiber was discussed on the background of literature review and own achievements. The role of erbium ions as NIR emitters as well as ytterbium ions in the process of stimulated emission has been explained and illustrated by several figures both from the literature and the author’s results. Glass-ceramics material advantage over glassy fibers was also considered and proved by several plots and images. The relations between the g-c materials and their optical features have been illustrated by results of SEM/TEM imaging, X-ray spectra, XRD and SAED patterns, thermal analysis (DTA/DSC) and a corresponding absorption/emission NIR spectra. Key words: fiber laser, rare earth ions, glass-ceramics, edfa, nanocrystals.1. INTRODUCTION A chance to establish the long distance waveguide communications appeared in early seventies due to super pure low-loss fused silica glass optical fibers (about 90% of SiO2) fabrication. Since silica fiber attenuation is wavelength dependent (Fig. 1), the term “optical fiber communication window" has been introduced and currently the third window (1550 nm) is utilized for long distance cables with attenuation better than 0.3 dB/km. In traditional optical communication systems a signal regeneration was achieved in the form of optoelectronic repeaters located every 20÷50 km of the fiber cable (Fig. 2). They used three steps of signal regeneration: optical-to-electric conversion, amplification, and shaping and finally electric-to-optical conversion. Currently, several more sophisticated solutions (optical amplifiers without signal conversion) have been invented (EDFA - Erbium Doped Fiber Amplifier, SOA - Semiconductor Optical Amplifier, RFA - Raman Fiber Amplifier) and of them the EDFA amplifiers seem to be most common. Their heart is silica (plus GeO2) glass erbium doped optical fiber (Fig. 3). Actually, the EDFA amplif więcej »
 

W książce przedstawiono strukturę, właściwości i zastosowanie tworzyw sztucznych w sposób ogólnie zrozumiały, a zarazem odwołujący się do gruntownej wiedzy naukowo-technicznej. Po krótkim zarysie aktualnych kierunków rozwojowych, książka wprowadza w budowę i strukturę tworzyw polimerowych - wiedzę konieczną do zrozumienia zachowania się tych materiałów pod obciążeniem mechanicznym, termicznym i chemicznym. Szczególny nacisk kładzie na ogólne właściwości mechaniczne, charakterystykę wytrzymałościowo- -odkształceniową, zachowanie przy długotrwałym odkształcaniu (najdłuższe krzywe pełzania), starzenie i degradację tworzyw, jak również naprężenia własne i orientację. Uwzględnia sposób działania więcej »
 

Podsumowanie XIV Konferencji Naukowo-Technicznej Techniki Komputerowe w Inżynierii TKI 2016. W dniach 18÷21 października 2016 roku odbyła się już po raz czternasty Konferencja Naukowo-Techniczna Techniki Komputerowe w Inżynierii TKI 2016. Tegoroczna edycja miała miejsce w hotelu Kuźnia Napoleońska w Teresinie k. Sochaczewa. Głównym organizatorem obecnej konferencji była Katedra Mechaniki i Informatyki Stosowanej Wydziału Mechanicznego Wojskowej Akademii Technicznej w Warszawie. W konferencji wzięło udział blisko 140 uczestników z uczelni i ośrodków naukowych z całej Polski. Konferencja TKI 2016 stanowi kontynuację cyklicznej Konferencji Naukowo-Technicznej Programy MES we Wspomaganiu Analizy, Projektowania i Wytwarzania, która odbywała się od 1996 roku oraz Konferencji Naukowo-Technicznej Odporność Udarowa Konstrukcji, która odbywała się od roku 2001. Tematyka Konferencji obejmuj więcej »