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PL
W pracy przedstawiono elektrochemiczną ocenę odporności korozyjnej azotowanego stopu tytanu Ti6Al4V. Badania korozyjne wykonano w 0,5M roztworze siarczanowym zakwaszonym do pH = 2 wykreślając krzywe potencjokinetyczne na różnych głębokościach warstwy wierzchniej. Grubość powstałej warstwy wierzchniej oceniono na podstawie badań strukturalnych oraz zmiany mikrotwardości na przekroju poprzecznym obrobionego powierzchniowo materiału. Stwierdzono, że przeprowadzona obróbka azotująca poprawia odporność korozyjną oraz znacznie utwardza powierzchnie badanego materiału. Uzyskana warstwa wierzchnia posiada budowę strefową przy czym najwyższą odporność korozyjną jak i najwyższą mikrotwardość wykazuje najbardziej zewnętrzna strefa azotków.
EN
The paper reports the electrochemical assessment of the corrosion resistance of the titanium alloy Ti6Al4V. Corrosion tests were carried out in a 0.5M sulphate solution acidified to pH = 2, while plotting potentiometric curves at varying depths of the top layer. The thickness of the produced top layer was assessed based on structural examination and change in microhardness over the cross-section of the surface treated material. It has been found that the nitriding treatment improves the corrosion resistance and considerably hardens the surface of the material under study. The obtained top layer exhibits a zonal structure, with the greatest corrosion resistance and the highest microhardness being shown by the outermost nitride zone.
EN
The aim of the study is to identify the endurance parameters of prosthetic crowns veneered with dedicated ceramics on metal, glass-ceramic, and ceramic frameworks. Metal frameworks were made using CAD/CAM milling technology and SLM technology, while the glass-ceramic and ceramic frameworks were produced using only the CAD/CAM milling technology. The research materials are samples replicating the layered structures of prosthetic crowns. The veneering procedure must ensure the adhesion of the ceramics to the loadbearing framework. The tests modelling the conditions of concentrated loads during chewing were carried out using the Instron 3345 testing machine. Determination of microhardness in cross-sections through layered structures of crowns was performed using the HMV Micro Hardness Tester. The comparison of force loading the indenter as a function of penetration depth indicates that the value of the maximum depth depends on the configuration of microhardness of the framework and dentine. The zirconium ceramics ZrO2 (3Y-TZP) – veneered with Elephant Sakura silica ceramics – should be indicated as the most advantageous material composition.
PL
Celem pracy jest identyfikacja parametrów wytrzymałościowych koron protetycznych licowanych dedykowanymi ceramikami na podbudowach metalowych, szklanoceramicznych i ceramicznych. Podbudowy metalowe zostały wytworzone w technologii frezowania CAD/CAM i w technologii SLM, a podbudowy szklanoceramiczne i ceramiczne w technologii frezowania CAD/CAM. Materiałem badań są próbki replikujące warstwowe struktury koron protetycznych. W wyniku procedury licowania musi być zapewniona adhezjaceramiki do podbudowy nośnej. Badania modelujące warunki skoncentrowanych obciążeń podczas żucia wykonano na maszynie wytrzymałościowej Instron 3345. Wyznaczenie mikrotwardości w przekrojach przez warstwowe struktury koron zrealizowano na maszynie HMV Micro Hardness Tester. Zestawienie siły obciążającej wgłębnik w funkcji głębokości penetracji wskazuje, że wartość maksymalnego zagłębienia, zależy od konfiguracji mikrotwardości podbudowy i mikrotwardości dentyny. Jako najkorzystniejszą kompozycję materiałową należałoby wskazać ceramikę cyrkonową ZrO2 (3Y – TZP) – licowaną ceramiką krzemionkową Elephant Sakura.
EN
Purpose: The purpose of the work is to synthesize and investigate the character of structure formation, phase composition and properties of model alloys Fe75Cr25, Fe70Cr25Zr5, and Fe69Cr25Zr5B1. Design/methodology/approach: Model alloys are created using traditional powder metallurgy approaches. The sintering process was carried out in an electric arc furnace with a tungsten cathode in a purified argon atmosphere under a pressure of 6·104 Pa on a water cooled copper anode. Annealing of sintered alloys was carried out at a temperature of 800°C for 3 h in an electrocorundum tube. The XRD analysis was performed on diffractometers DRON-3.0M and DRON-4.0M. Microstructure study and phase identification were performed on a REMMA-102-02 scanning electron microscope. The microhardness was measured on a PMT-3M microhardness meter. Findings: When alloying a model alloy of the Fe-Cr system with zirconium in an amount of up to 5%, it is possible to obtain a microstructure of a composite type consisting of a mechanical mixture of a basic Fe2(Cr) solid solution, solid solutions based on Laves phases and dispersive precipitates of these phases of Fe2Zr and FeCrZr compositions. In alloys of such systems or in coatings formed based on such systems, an increase in hardness and wear resistance and creep resistance at a temperature about 800°C will be reached. Research limitations/implications: The obtained results were verified during laser doping with powder mixtures of appropriate composition on stainless steels of ferrite and ferrite-martensitic classes. Practical implications: The character of the structure formation of model alloys and the determined phase transformations in the Fe-Cr, Fe-Cr-Zr, and Fe-Cr-B-Zr systems can be used to improve the chemical composition of alloying plasters during the formation of ferrite and ferrite-martensitic stainless steel coatings. Originality/value: The model alloys were synthesized and their phase composition and microstructure were studied; also, their microhardness was measured. The influence of the chemical composition of the studied materials on the character of structure formation and their properties was analysed.
EN
Purpose: A new composite material was prepared and Different properties such as hardness and tribological behaviour of the fabricated metal matrix composite (MMC) was investigated and compared with the base AZ61A magnesium alloy. Design/methodology/approach: For the current research work, state-of-the-art technology, Friction stir processing (FSP) was performed to develop magnesium based AZ61A/TiC composite at optimized set of machine parameters. Findings: Increasing tool rotational speed ultimately leads in enhanced hardness, which further gives superior tribological properties as compared to base AZ61A alloy. Wear observations suggests a combination of abrasive and adhesive wear mechanism. Research limitations/implications: More microstructural and mechanical properties can be examined. Practical implications: The idea behind selecting AZ61A is mainly due to its increasing use in bicycle pedals and military equipment’s where at certain places it needs to encounter friction. In this current work, microhardness study and wear behaviour of AZ61A/TiC composite processed via FSP were examined. Originality/value: Paper is completely new and no work has been done till date considering this material and preparing composite with nanoparticles TiC.
EN
Crystal structure and phase composition of stainless steel substrates (AISI 304 type) was studied and it was found that they adopted the cubic symmetry. The calculated elementary cell parameter for the mayor Fe-Ni phase (weight fraction 99%) was a = 3.593 Å, whereas the mean grain size was = 2932 Å. Morphology of the stainless steel substrate surface was studied with profilometry. Mechanical properties of the stainless steel substrates and stainless steel substrates coated with ceramic layer of barium strontium titanate were studied with microhardness tester. For measurements performed according to the Vickers method the average microhardness was found HV = 189 or HV = 186 for the “in-line” and “mapping” measurement pattern, respectively. The sol-gel method was used to coat the surface of the stainless steel substrate with a thin ceramic layer of the chemical composition Ba0.6 Sr0.4 TiO3 . It was found that the stainless steel substrate covered with sol-gel deposited ceramic coating exhibited the average hardness within the range HV = 217 up to HV = 235 for loading force F = 98 mN and F = 0.98 N, respectively. The Knopp method was also used and it was found that the stainless steel substrate with Ba0.6 Sr0.4 TiO3 coating exhibited hardness HK = 386.
EN
The article provides results of the microstructure examinations and mechanical properties (hardness and microhardness tests) of the welded joint T91 steel taken from the live steam pipeline. Examined joint has been exploited for about 45 000 hours in a temperature of 535°C and the steam pressure equals to 13.5 MPa. Examined joint was made as a double bead by the additional materials with a different chemical composition. It was proved that the joint was characterized by a differential microstructure on the cross-section of the weld. Moreover, decarburized zone in the lower alloyed material and carbides zone in the higher alloyed material were revealed in the weld line and on the boundary penetration of beads. Furthermore, it was shown that the main mechanism of a joint degradation is a privileged precipitation of carbides on the grain boundaries, and an increase of their size.
EN
Purpose: Determine the possibility of modifying aluminium alloys of the Al-Si system with an ultrafine SiC modifier with a particie size of 3-5 pm. Design/methodology/approach: Processing of the Al-Si alloy was carried out by introducing an ultrafine modifier in the amount of 0.1, 0.2, or 0.3 wt.%. Silicon carbide (SiC) with a particle size in the range of 3-5 pm was used as a modifier. To study the microstructure of the formed surface layers, a metallographic analysis was performed according to the standard method on a microscope MIKPOTEX® MMT-14C using TopView software. Microhardness studies of the samples were carried out on a Vickers microhardness tester NOVOTEST TC-MKV1. The microstructure of castings of the AlSi12 grade was studied at magnification from 100 to 400 times on the horizontal and vertical surfaces of the samples after etching with a 2% NaOH aqueous solution. Findings: Aluminium cast alloy of Al-Si system has been synthesized with the addition of 0.1, 0.2, and 0.3 wt.% ultrafine SiC modifier. It was found that the modification of the AlSi12 alloy by SiC particles of 3-5 pm in size led to an improvement of its microstructure due to the reduction of the volume fraction of micropores and primary Si crystals. It was shown that the AlSi12 aluminium alloy due to the modification by 0.2 wt.% SiC has the best micromechanical properties and macrostructure density. Research limitations/implications: The obtained research results are relevant for cast specimens of the indicated sizes and shapes. The studies did not take into account the influence of the scale factor of the castings. Practical implications: The developed modification technology was recommended for use in the conditions of the foundry "Dnipropetrovsk Aggregate Plant" (Dnipro, Ukraine). Originality/value: The technology of AlSi12 alloy modification of ultrafine SIC modifier with a particle size of 3-5 pm was used for the first time.
EN
Purpose: The proposed research aims to determine the expediency of surface treatment of vanadium alloys of V-Cr and V-Ti systems due to irradiation of their surfaces with low- temperature nitrogen plasma using plasma torch NO-01. Design/methodology/approach: The investigation of microstructure and X-ray fluorescence analysis (XRF) of the samples were performed using an electron microscope TESCAN Vega3. The microhardness (Vickers hardness) of the samples was measured before and after surface treatment. The study of corrosive properties of the surface layers was performed by an electrochemical impedance spectroscopy (EIS) method. Corrosion damages were identified using impedance dependences. Findings: The microstructure of the surface layers of the V-8Ti, V-15Cr, and V-35Cr alloys in the initial state and after plasma treatment have been investigated. The chemical composition of the surface layers is determined and comparative measurements of the microhardness of these alloys are carried out. Corrosion-electrochemical properties (corrosion potentials, electrochemical impedance spectroscopy and constructed potential-dynamic polarization curves) of investigated alloys after treatment with nitrogen plasma are evaluated. Research limitations/implications: The results obtained using laboratory samples should be checked at the conditions of power equipment operation. Practical implications: This treatment has advantages over other methods of surface engineering since it provides strong surface plastic deformation and the possibility of formation of secondary phases resulting in increases in surface hardness and corrosion resistance. Originality/value: Vanadium alloys have significant advantages over other structural materials due to their high thermal conductivity and swelling resistance, high strength and plasticity up to temperatures of 700-800°C, and good weldability.
EN
The paper discusses the effect of upsetting ratio on distribution of the microhardness in longitudinal sections of hydroformed axisymmetric elements made from P265TR1 steel. The experimental research of hydroforming was carried out at a special stand which included a press with tooling and a hydraulic feeding system of oil. The measurements of microhardness were taken with a MATSUZAWA MMT-X3 Vickers hardness tester at a load of 100 g. The samples used in the tests were prepared from tube segments with a thin-wall ratio of 0.045. In the experiment, steel components were formed at upsetting coefficients of 0.07 and 0.09. For an established course of pressure and upsetting force, a series of steel components with exact representation of the die-cavity was formed. The paper provides a comparison of the microhardness distributions in three zones of longitudinal sections of axisymmetric elements at different degrees of material deformation. The greatest values of microhardness occurred in the area of cap for components at an upsetting coefficient 0.09.
EN
The paper presents the research data on structure, phase composition, defect substructure state, and microhardness of surface layers in the piston alloy Al-10wt%Si-2wt%Cu irradiated by an electron beam with various energy densities and pulse times. An important finding to emerge from the study is that the processing by an electron beam with an energy density of 10 J/cm2 brings about slight surface melting, whereas a weak thermal impact of an electron beam hardly changes the phase composition. Once an energy density of an electron beam is set 30 J/cm2, intermetallic compounds dissolve and numerous micropores arise. Irradiating by an electron beam with an energy density of 50 J/cm2, randomly located microcracks are detected on the treated surface with no regard to a pulse time. A structure of high-speed cellular crystallization with cells from 500 to 600 nm forms in the surface layer. A thickness of the modified layer is related to a beam energy density. As a beam energy density goes up, a thickness of a high-speed cellular crystallization layer increases. Atoms of Si, Cu, Ni, as well as a small quantity of Fe and Mg are detected in the surface, in thin layers surrounding crystallization cells. In a layer 60-80 μm below the irradiated surface, in material between high-speed crystallization cells, there are Si atoms and an insignificant number of Cu atoms. An analysis of a deeper material part has shown a structure similar to the as cast alloy. A drop of microhardness – if compared with the as cast material – is reported at an energy density of 10 J/cm2 because an energy amount supplied by an electron beam to the alloy surface is insufficient for melting of the material and dissolution of the intermetallic phase. A raise of a beam energy density up to 20-50 J/cm2 causes a max increase of microhardness up to 1.13 GPa for 40 J/cm2, 50 μs, and up to 1.16 GPa for 40 J/cm2, 200 μs.
PL
W silnikach, w których stosuje się zasilanie sprężonym gazem ziemnym, LPG oraz innymi paliwami gazowymi, obserwuje się konieczność częstszej wymiany zaworów wydechowych. Zawory te w silnikach spalinowych mogą być eksploatowane przez krótszy czas niż ich odpowiedniki w silnikach zasilanych benzyną i olejem napędowym. Najbardziej narażona na degradację jest przylgnia zaworu wydechowego. Wynika to z temperatury spalania gazu ziemnego w komorze spalania oraz temperatury spalin mających kontakt z zaworem. W pracy przedstawiono porównawczy rozkład mikrotwardości w zaworach wydechowych napawanych fazą międzymetaliczną Fe3Al oraz stellitem.
EN
In engines, fuelled with concentrated natural gas, LPG, and other gaseous fuels, the necessity for more frequent replacement of exhaust valves is observed. These valves in combustion engines may be operated for a shorter period than their equivalents in engines fuelled with petrol and diesel oil. The exhaust valve face is most exposed to degradation. This results from the combustion temperature of natural gas in the combustion chamber and the temperature of exhaust gas in contact with the valve. The paper presents a comparative distribution of microhardness in exhaust valves pad welded with Fe3Al intermetallic phase and stellite.
EN
On a fragment of the rim of a railway wheel removed from service, the volume of the metal with non-metallic inclusions located near the tread surface was investigated. The use of the microhardness measurement technique made it possible to establish the nature of strain hardening of carbon steel near non-metallic inclusions. It showed that with a normal orientation of the plastic flow relative to the inclusion surface, the metal volumes undergo hardening. In proportion to the appearance of a fraction of the tangential component of the deformation near the nonmetallic inclusion, a decrease in the degree of hardening of the metal was observed.
EN
The systematization results of microstructure studies of carbon steel has made it possible to explain the mechanism of formation of certain damages to the rolling surface of railway wheels during operation. The evaluation ability of metal to strain hardening was used to explain the nature of the influence compactly located non-deformable dispersed particles on the strength properties steel during cold plastic deformation. In the process of the interaction of a railway wheel with a rail, successively occurring heterogeneities in the distribution of the plastic flow metal are one of the main reasons for the formation of defects on the rolling surface of the wheel.
EN
The Al2O3+TiO2 coatings are of the interest of surface engineering due to their high hardness and wear resistance but also increased toughness, when compared to pure Al2O3 ones. This article describes the deposition of Al2O3+3 wt.% TiO2 coatings by Atmospheric Plasma Spraying (APS) technique. The commercial AMI 6300.1 powder (-45 + 22 μm) was used as a feedstock. The 2k+1 spraying experiment, based on two variables, namely spray distance and torch velocity, was designed. The samples were characterized in the terms of morphology, microstructure, microhardness and roughness. It was observed that the shorter spray distance resulted in lower porosity, higher microhardness and lower roughness of coatings.
PL
Powłoki Al2O3+TiO cieszą się zainteresowaniem inżynierii powierzchni ze względu na wysoką twardość i odporność na zużycie ścierne przy jednocześnie zwiększonej odporności na kruche pękanie, w porównaniu z powłokami na bazie czystego Al2O3. W artykule opisano proces natryskiwania powłok Al2O3+3% wag. TiO2 metodą proszkowego natryskiwania plazmowego (APS). Jako materiał wsadowy wykorzystano komercyjnie dostępny proszek AMI 6300.1 (-45+22 μm). Zaprojektowano plan eksperymentu 2k+1, oparty na dwóch zmiennych - odległości natryskiwania i prędkości przesuwu palnika względem podłoża. Próbki charakteryzowano pod względem morfologii, mikrostruktury, mikrotwardości oraz chropowatości. Zaobserwowano, że zmniejszenie odległości natryskiwania pozwala uzyskać powłoki o mniejszej porowatości, większej twardości i niższej chropowatości.
EN
This paper presents two methods of introducing boron into the surface layer of iron alloys, namely diffusion boronizing by means of the powder method and laser alloying with a TRUMPF TLF 2600 Turbo CO2 gas laser. Amorphous boron was used as the chemical element source. As regards diffusion drilling, the influence of temperature and time on the properties of the layer was tested. During the laser alloying, the influence of the thickness of the boriding paste layer as well as the power and laser beam scanning velocity was determined. How the carbon content in steel and alloying elements in the form of chromium and boron influence the structure of the surface layer was tested. To achieve this object, the following grades of steel were used: C45, C90, 41Cr4, 102Cr6, and HARDOX boron steel. The microhardness and wear resistance of the obtained boron-containing surface layers were tested. A Metaval Carl Zeiss Jena light microscope and a Tescan VEGA 5135 scanning electron microscope, a Zwick 3212B microhardness tester, and an Amsler tribotester were used for the tests. The structure of the diffusion- borided layer consists of the needle-like zone of FeB + Fe2B iron borides about 0.15 mm thick, with a good adhesion to the substrate of the steel subjected to hardening and tempering after the boriding process. After the laser alloying, the structure shows paths with dimensions within: width up to 0.60 mm, depth up to 0.35 mm, containing a melted zone with a eutectic mixture of iron borides and martensite, a heat affected zone with a martensitic-bainitic structure and a steel core. The microhardness of both diffusion-borided and laser-borided layers falls within the range of 1000 – 1900 HV0.1, depending on the parameters of the processes. It has been shown that, apart from the structure and thickness of the layer containing boron and microhardness, the frictional wear resistance depends on the state of the steel substrate, i.e. its chemical composition and heat treatment. The results of testing iron alloys in the borided state were compared with those obtained only after the heat treatment.
PL
W pracy przedstawiono dwie metody wprowadzania boru do warstwy wierzchniej stopów żelaza, a mianowicie borowanie dyfuzyjne z zastosowaniem metody proszkowej oraz stopowanie laserowe za pomocą lasera gazowego CO2 TRUMPF TLF2600 Turbo. Jako źródło pierwiastka użyto bor amorficzny. Zbadano w przypadku borowania dyfuzyjnego wpływ temperatury i czasu na właściwości warstwy. Przy stopowaniu laserowym określono oddziaływanie grubości warstwy pasty do borowania oraz mocy i szybkości posuwu wiązki laserowej. Przeanalizowano wpływ zawartości węgla w stali oraz dodatków stopowych w postaci chromu i boru na strukturę warstwy wierzchniej. W tym celu do badań zastosowano stale: C45, C90, 41Cr4, 102Cr6, stal borową HARDOX. Zbadano mikrotwardość oraz odporność na zużycie przez tarcie otrzymanych warstw wierzchnich zawierających bor. Do badań zastosowano mikroskop świetlny Metaval Carl Zeiss Jena i elektronowy mikroskop skaningowy Tescan VEGA 5135, mikrotwardościomierz Zwick 3212B oraz tribotester typu Amsler. Struktura dyfuzyjnej warstwy borowanej składa się z iglastej strefy borków żelaza FeB+Fe2B o grubości do ok. 0,15 mm o dobrej przyczepności z podłożem stali poddanej hartowaniu i odpuszczaniu po procesie borowania. Po stopowaniu laserowym w strukturze występują ścieżki o wymiarach: szerokość do 0,60 mm, głębokość do 0,35 mm, zawierające strefę przetopioną z mieszaniną eutektyczną borków żelaza oraz martenzytu, strefę wpływu ciepła o strukturze martenzytyczno-bainitycznej oraz rdzeń stali. Mikrotwardość warstw borowanych dyfuzyjnie i laserowo mieści się w zakresie 1000÷1900 HV0.1, w zależności od parametrów procesów. Wykazano, że poza strukturą i grubością warstwy zawierającej bor oraz mikrotwardością, odporność na zużycie przez tarcie zależy od stanu podłoża stali, czyli jej składu chemicznego i obróbki cieplnej. Wyniki badań stopów żelaza w stanie borowanym porównano z otrzymanymi tylko po obróbce cieplnej.
EN
This work is devoted to the research of the influence of the technological parameters of electrolytic-plasma surface hardening on the structure and tribological properties of the surface of samples of the retaining steel Mark 2. Electrolytic-plasma surface hardening was carried out in an electrolyte from an aqueous solution of 10% urea and 10% sodium carbonate. According to the result of metallographic and X-ray diffraction analysis, it was determined that the phase composition of steel Mark 2 after processing varies, and fine martensite with a small amount of troostite and iron oxide is formed on the surface of the samples. Tribological experiments of samples without lubrication were carried out. These experiments have shown that all the samples studied have an increased wear resistance, which may be associated with the formation of a fine-grained martensitic structure. It was shown that from the point of view of the complex of the properties obtained, and the most promising is electrolytic-plasma action with a treatment time of 4 s.
PL
Praca opisuje wpływ parametrów technologicznych elektrolityczno-plazmowego hartowania powierzchniowego na strukturę i właściwości tribologiczne stali „Mark 2“ (GOST 398-96). Stal GOST 398-96 – „Mark 2” jest niestopową stalą średniowęglową i jest najczęściej stosowanym materiałem na obręcze kół kolejowych w Kazachstanie.Hartowanie elektrolityczno-plazmowe przeprowadzono w 10-proc. roztworze wodnym mocznika z dodatkiem 10% węglanu sodu. Na podstawie wyników analizy metalograficznej i badań z zastosowaniem dyfrakcji rentgenowskiej ustalono, że skład fazowy stali „Mark 2” po obróbce cieplnej jest zróżnicowany a na powierzchni próbek powstaje drobny martenzyt z niewielką ilością trostytu i tlenku żelaza. Przeprowadzone badania tribologiczne podczas tarcia suchego wykazały zwiększenie odporność na zużycie próbek poddanych hartowaniu elektrolityczno-plazmowemu w stosunku do próbek w stanie nieobrobionym cieplnie. Efekt ten może być związany z tworzeniem się na powierzchni drobnoziarnistej struktury martenzytycznej. Badania porównawcze próbek stalowych poddanych obróbce cieplnej z różnymi parametrami technologicznymi wykazały, że najbardziej korzystna jest obróbka elektrolityczno-plazmowa wykonana w czasie 4 s.
EN
This work presents the results of experimental studies on the application of surface plasma hardening to improve the tribological characteristics of steel marks of 40CrNi, 20Cr2Ni4A, and 34CrNi1Mn. According to the obtained results, it was established that, after plasma treatment, a modified layer with a thickness of 1–1.2 mm with high hardness and wear resistance is formed, consisting of a hardened layer of fine-grained martensite and, an intermediate layer of perlite and martensite. It was determined that, after treatment with a heating time of 3 min, the microhardness of steels 40CrNi and 20Cr2Ni4A doubles, and the steel 34CrNi1Mn increases 1.6 times, depending on the initial state, and the wear resistance of all steel samples increases, on average, 30 times.
PL
W niniejszej pracy przedstawiono wyniki eksperymentalnych badań nad stosowaniem utwardzania plazmy powierzchniowej w celu poprawy charakterystyki tribologicznej próbek stalowych 40CrNi, 20Cr2Ni4A i 34CrNi1Mn. Zgodnie z uzyskanymi wynikami ustalono, że po obróbce plazmowej powstaje zmodyfikowana warstwa o grubości 1–1,2 mm o dużej twardości i odporności na ścieranie, składająca się z utwardzonej warstwy drobnoziarnistego martenzytu i warstwy pośredniej z perlitu i martenzytu. Stwierdzono, że po obróbce z czasem ogrzewania 3 min mikrotwardość stali 40CrNi i 20Cr2Ni4A podwaja się, a stal 34CrNi1Mn wzrasta 1,6 razy, w zależności od stanu początkowego, i odporność na zużycie wszystkich próbek stali wzrasta średnio 30 razy.
EN
The paper addresses the problem of assessing the operational quality of the surface layer (SL) of polymerceramic composites. These materials are used in conservative dentistry to reproduce geometrical features of human lateral teeth carrying the largest biomechanical loads. The chewing process causes that applications of these materials partly work in sliding friction conditions. Their durability in the biotribological node depends on the mechanical contact loads and is related to the influence of oral environment factors. In this study, we assessed the impact of cyclical hydro-thermal shocks, among others, related to the consumption of hot and cold food, on the condition of SL polymer-ceramic composites. In our own research, cyclic hydro-thermal shocks with cycle temperatures of 5–55°C were simulated. Evaluation of the remaining surface strength (after implementation of the hydro-thermal cycles) was made on the basis of microhardness measurements using the Vickers method. Calculations of the damage function value were made. It has been demonstrated that the durability curves depend on the number of fatigue cycles and the structure of the material. In addition, it has been shown that the phenomenological measure of SL damage, assuming accumulation of damage, is useful in the assessment of the operational quality of polymer-ceramic composites.
PL
W pracy podjęto problem oceny jakości eksploatacyjnej warstwy wierzchniej (WW) kompozytów polimerowoceramicznych. Tworzywa te są stosowane w stomatologii zachowawczej do odtwarzania cech geometrycznych zębów ludzkich bocznych, przenoszących największe obciążenia biomechaniczne. Proces żucia pokarmów powoduje, że aplikacje z tych tworzyw pracują częściowo w warunkach tarcia ślizgowego. Ich trwałość w węźle biotribologicznym zależy od obciążeń mechanicznych kontaktowych oraz związana jest z oddziaływaniem czynników środowiska jamy ustnej. W przedmiotowej pracy oceniono wpływ cyklicznych wstrząsów hydrotermicznych, związanych m.in. ze spożywaniem gorących i zimnych pokarmów, na stan WW kompozytów polimerowo-ceramicznych. W badaniach własnych symulowano cykliczne wstrząsy hydrocieplne o temperaturach cyklu 5–55°C. Oceny pozostałej wytrzymałości powierzchniowej (po realizacji cykli hydrotermicznych) dokonano na podstawie pomiarów mikrotwardości metodą Vickersa. Wykonano obliczenia wartości funkcji uszkodzenia. Wykazano, że krzywe trwałości zależą od liczby cykli zmęczeniowych oraz od struktury tworzywa. Ponadto wykazano, że fenomenologiczna miara uszkodzenia WW, zakładająca kumulację uszkodzeń, jest przydatna w ocenie jakości eksploatacyjnej kompozytów polimerowo-ceramicznych.
EN
In this paper, the results of tribological, microscopic and mechanical research of Al2O3 and Al2O3 + 40 wt.% TiO2 coatings manufactured by atmospheric plasma spraying (APS) were presented. The feedstock materials were Al2O3 (Metco 6103, Oerlikon Metco) and Al2O3 + 40 wt.% TiO2 (Metco 131VF, Oerlikon Metco) powders with the average grain size of 30 μm. The stainless steel (X5CrNi18-10) coupons had a diameter equal to 25 mm and 2 mm of thickness. The morphology and microstructure of obtained coatings were tested by scanning electron microscope (SEM). Then adhesion tests and tribological examinations by ball-on-disc (BoD) mode in technical dry friction conditions were carried out. During BoD testing, the load of 5 N was used. It was concluded that the Al2O3 coating was characterized by higher wear resistance and microhardness, but, at the same time, it was of lower fracture toughness than the Al2O3 + 40 wt.% TiO2 coating.
PL
W artykule przedstawiono wyniki badań tribologicznych, mikroskopowych oraz mechanicznych powłok Al2O3 oraz Al2O3 + 40% wag. TiO2, natryskanych metodą atmosferycznego natryskiwania cieplnego (APS). Materiałem na powłoki były proszki Al2O3 (Metco 6103, Oerlikon Metco) oraz Al2O3 + 40% wag. TiO2 (Metco 131VF, Oerlikon Metco) o średniej wielkości cząstek wynoszącej 30 μm. Jako podłoże zostały użyte krążki ze stali austenitycznej X5CrNi18-10 o średnicy 25 mm i grubości 2 mm. Morfologię i mikrostrukturę uzyskanych powłok oceniono przy pomocy skaningowego mikroskopu elektronowego (SEM). Po określeniu przyczepności powłok wykonano badania tribologiczne w styku kula–tarcza w warunkach tarcia technicznie suchego. Zastosowano obciążenie 5 N. Na podstawie przeprowadzonych badań stwierdzono, że powłoki na bazie Al2O3 wykazują większą odporność na zużycie ścierne oraz wyższą mikrotwardość, ale jednocześnie mniejszą odporność na kruche pękanie (KIC) w porównaniu z powłokami na bazie Al2O3 + 40% wag. TiO2.
PL
Zbadano wpływ podwyższonej i wysokiej temperatury na właściwości antykorozyjne powłoki diamentopodobnej (DLC) wyprodukowanej metodą chemicznego osadzania z fazy gazowej wspomaganej plazmą (PECVD) na podłożu stali S355 (S355/DLC). Test korozyjny badanych materiałów prowadzono metodą elektrochemiczną. Środowisko korozyjne, stanowił kwaśny roztwór chlorku sodu. Wykazano, że powłoka DLC skutecznie zabezpiecza powierzchnię stali S355 przed kontaktem z agresywnym środowiskiem korozyjnym. Obróbkę termiczną S355/DLC prowadzono w atmosferze gorącego powietrza w temperaturze 400 lub 800 °°. Stwierdzono, że po obróbce termicznej w temperaturze 400 °C, powłoka DLC częściowo traci swoje antykorozyjne właściwości. W wyniku zmian struktury powierzchni S355/DLC mikrotwardość (HV) warstwy DLC wzrasta. Natomiast po obróbce termicznej w temperaturze 800 °C powłoka węglowa na powierzchni stali S355 ulega zniszczeniu, a tym samym traci swoje ochronne działanie.
EN
Influence of higher and high temperature on anti-corrosive properties of a diamond-like carbon coating (DLC), produced by plasma enhanced chemical vapor deposition (PECVD) on S355 steel substrate (S355/DLC), was investigated. Corrosion test of materials was carried out by electrochemical method. Corrosive environment was an acidified sodium chloride solution. It has been demonstrated that the DLC coating effectively protects the S355 steel surface from contact with an aggressive corrosive environment. The thermal treatment was carried out in an atmosphere of hot air at temperatures of 400 or 800 °C. It was found that after thermal treatment at 400 °C the DLC coating partially loses its anti-corrosive properties. Due to changes in the surface structure of the S355/DLC layer its microhardness (HV) increases. However, after heat treatment at 800 °C the carbon coating is destroyed and thus loses its protective effect.
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