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EN
Purpose: The aim of the paper is to determine influence of plastic deformation rate at room temperature on structure and mechanical properties of high-Mn austenitic Mn-Al-Si 25-3-3 type steel tested at room temperature. Design/methodology/approach: Mechanical properties of tested steel was determined using Zwick Z100 static testing machine for testing with the deformation speed equal 0.008 s-1, and RSO rotary hammer for testing with deformation speeds of 250, 500 and 1000s-1. The microstructure evolution samples tested in static and dynamic conditions was determined in metallographic investigations using light microscopy as well as X-ray diffraction. Findings: Based on X-ray phase analysis results, together with observation using metallographic microscope, it was concluded, that the investigated high-Mn X13MnAlSiNbTi25-3-3 steel demonstrates austenitic structure with numerous mechanical twins, what agrees with TWIP effect. It was demonstrated, that raise of plastic deformation rate produces higher tensile strength UTS and higher conventional yield point YS0.2. The UTS strength values for deformation rate 250, 500 and 1000 s-1 grew by: 35, 24 and 31%, appropriately, whereas in case of YS0.2 these were: 7, 74 and 130%, accordingly, in respect to the results for the investigated steel deformed under static conditions, where UTS and YS0.2 values are 1050 MPa and 700 MPa. Opposite tendency was observed for experimentally measured uniform and total relative elongation. Homogeneous austenitic structure was confirmed by X-ray diffractometer tests. Research limitations/implications: To fully describe influence of strain rates on structure and mechanical properties, further investigations specially with using transmission electron microscope are required. Practical implications: Knowledge about obtained microstructures and mechanical properties results of tested X13MnAlSiNbTi25-3-3 steel under static and dynamic conditions can be useful for the appropriate use of this type of engineering material in machines and equipment susceptible to static or dynamic loads. Originality/value: The influence of plastic deformation at room temperature under static and dynamic conditions of new-developed high-manganese austenitic X13MnAlSiNbTi25-3-3 steels were investigated.
2
Content available remote Wpływ włókien z polietylenu o dużej gęstości na właściwości powłok
PL
Opracowano receptury i wykonano próbki farb rozpuszczalnikowych i wodorozcieńczalnych na żywicach akrylowych, zawierających włókna z polietylenu o dużej gęstości (HDPE) i, w celach porównawczych, bez włókien. W badaniach zastosowano włókna o różnej długości i średnicy, w ilości 1% mas. i 3% mas. w przeliczeniu na farbę. Przebadano właściwości farb w stanie ciekłym, właściwości fizyko-mechaniczne (giętkość, twardość, tłoczność, odporność na uderzenie, wytrzymałość na rozciąganie, przyczepność do podłoża) oraz ochronne (odporność na wodę, mgłę solną i alkalia). Wykonano również badania struktury powłok metodą elektronowej mikroskopii skaningowej (SEM). Na podstawie wyników badań stwierdzono, że dodatek włókien nie wpływa w istotny sposób na właściwości fizyko-mechaniczne powłok, pomimo poprawy struktury powłok dzięki gęstemu upakowaniu płatkowego talku, włókien i cząstek pigmentu. Najlepszą odporność na mgłę solną wykazała powłoka farby rozpuszczalnikowej z dodatkiem 1% najmniejszego włókna o długości ok. 0,1 mm i średnicy 5 μm (ESS5F), a zwiększenie do 3% dodatku włókien małych i średnich (ESS5F i E380F) poprawiło odporność powłok zarówno na mgłę solną, jak i na alkalia.
EN
Acryl solvent- and water-borne paints containing high density polyethylene (HDPE) fibers and, for comparison, without fibers were formulated. Fibers of various diameter and length were used in the amount of 1% wt. and 3% wt. in terms of paint. The properties of paints in liquid state, physico-mechanical properties (flexibility, drawability, hardness, impact resistance, tensile strength, adhesion) and protective properties (water, salt spray and alkali resistance) of coatings were determined. The coating structure was also examined by scanning electron microscopy (SEM). Based on test results it was found that the addition of fibers does not significantly affect physico-mechanical properties of the coatings, despite the improvement of the coating structure due to the dense packing of flaky talc, fibers and pigment particles. The best resistance to salt spray was demonstrated by the solvent-borne coating with the addition of 1% wt. the smallest fibers with the length of approx. 0.1 mm and the diameter of 5 μm (ESS5F), and increasing the addition of small and medium fibers (ESS5F and E380F) to 3% wt. improved both salt spray and alkali resistance.
EN
This paper presents research results of zinc oxide thin films deposited on a glass substrate with use of ALD method. Our researches focused on analyzing of the influence of ALD deposition process temperature on the morphology and transparency of thin layers. The morphology was examined using both scanning and transmission electron microscopes. Transparency study was performed by UV-VIS spectroscopy. For our experiments, two sets of the coating have been prepared, differing in temperature and number of cycle used during the preparation process. The first set was deposited in 100 cycles, second one in 500 cycles. Each set of tested coating contained samples prepared at different temperatures.
EN
In the study, particle size distribution of the MIEX® resin was presented. Such analyses enable to determinate whether presence of fine resin fraction may be the reason for unfavorable membrane blocking during water purification by the hybrid MIEX®DOC – microfiltration/ultrafiltration systems. Granulometric analysis of resin grains using the laser diffraction particle size analyzer (laser granulometer) was carried out as well as the microscopic analysis with scanning electron microscope. The following samples were analyzed: samples of fresh resin (a fresh resin – not used in water treatment processes) and samples of repeatedly used/regenerated resin that were collected to analysis during mixing and after sedimentation process. Particle size distribution was slightly different for fresh resin and for repeatedly used/regenerated resin. The grains sizes of fresh resin reached approximately 60 μm (d10), 120 μm (d50) and 220 μm (d90). Whereas the sizes of repeatedly used/regenerated resin were about 15 μm (d10), 40 μm (d50) and 115-130 μm (d90). The smallest resin grains sizes were in the range of 0.3-0.45 μm. This ensures that the ultrafiltration membranes retain all resin grains, even the smallest ones. Whereas the microfiltration membranes must be appropriately selected to guarantee full separation of the resin grains and at the same time to exclude a membrane pores blocking.
EN
Mg60 Zn35 Ca5 amorphous powder alloys were synthesized by mechanical alloying (MA) technique. The results of the influence of high-energy ball-milling time on amorphization of the Mg60 Zn35 Ca5 elemental blend (intended for biomedical application) were presented in the study. The amorphization process was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM). Initial elemental powders were mechanically alloyed in a Spex 8000 high-energy ball mill at different milling times (from 3 to 24 h). Observation of the powder morphology after various stages of milling leads to the conclusion that with the increase of the milling time the size of the powder particles as well as the degree of aggregation change. The partially amorphous powders were obtained in the Mg60 Zn35 Ca5 alloy after milling for 13-18h. The results indicate that this technique is a powerful process for preparing Mg60 Zn35 Ca5 alloys with amorphous and nanocrystalline structure.
EN
The paper presents the results of research studies involving the ceramic-metal tool materials with the deposited nitride coatings on the basis of aluminium, titanium and silicon. The cathodic arc evaporation with lateral rotating cathodes method was used for deposition of nanocrystalline, wear resistant nitride coatings – AlTiSiN type. Structural examinations are presented of the applied coatings and their support material made on the scanning electron microscope (SEM) and the scanning/transmission electron microscope (STEM). Chemical composition analysis as a function of the distance from the specimen surface, the so-called profile analysis, were carried out also. The structural analysis confirms that deposited multilayer coatings have dense microstructure without any visible porosity and delamination. It was found that the investigated coatings have nanocrystalline structure and consisting of fine crystallites even less than 6nm. Lattice deformations and numerous structural defects were also observed in the nanolayers. Depositing the AlTiSiN coatings results in the significant hardness increase within the range of 2252 ±256 to 2908 ±295 HV0.01.
EN
Metal matrix composite (MMC) surface layers reinforced by WC were fabricated on armor steel ARMOX 500T plates via a laser surface alloying process. The microstructure of the layers was assessed by scanning electron microscopy and X-ray diffraction. The surface layers having the WC fraction up to 71 vol% and an average hardness of 1300 HV were produced. The thickness of these layers was up to 650 μm. The addition of a titanium powder in the molten pool increased the wettability of WC particles by the liquid metal in the molten pool increasing the WC fraction. Additionally, the presence of titanium resulted in the precipitation of the (Ti,W)C phase, which significantly reduced the fraction of W-rich complex carbides and improved a structural integrity of the layers.
EN
The article describes the morphology of carbon-metal nanocomposites consisting of nanostructured rhenium permanently attached to carbon nanomaterials, in the form of single-walled (SWCNTs), double-walled (DWCNTs) or multi-walled carbon nanotubes (MWCNTs). Such nanocomposites are produced as a result of the high-temperature reduction of a rhenium precursor, including HReO4 or NH4ReO4, to metallic rhenium, deposited on the previously functionalised carbon nanomaterials in the form of nanoparticles whose size and dispersion are dependent upon the conditions of a technological process. Microscopic examinations carried out with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed a differentiated structure of the presented nanocomposites depending on impregnation time in a rhenium precursor, which is one of the manufacturing steps of such materials. It has been demonstrated that longer impregnation time brings favourable results for material homogeneity in the whole volume. Moreover, the Raman spectroscopy results of functionalised carbon nanotubes and carbon nanotubes decorated with rhenium also has been presented.
EN
This work presents studies of the structure and functional properties of coatings deposited onto indexable inserts made of nitride and sialon tool ceramics with the required properties, i.e. high adhesion, niicrohardness. high resistance to abrasive and diffusion wear in working conditions of high-performance cuttings tools. In the present paper the results of the investigations of the structure, texture, mechanical and functional properties of the Ti(C,N), (Ti.Al)N, Ti(C.N)+(Ti,Al)N coatings were presented. The 80% increase in the hardness of the coatings in comparison to the substrate material was reported. Test coatings are characterized by good adhesion to the substrate. The maximum Lc load of (Ti A1)N coat applied to the substrate from the nitride ceramics is equal to 42 N. In the studied coatings compressive stresses were found. The results of mechanical properties investigations, especially tribological ones correlate with the results of exploitation tests carried out during the cutting test.
10
Content available Internal stresses in PVD coated tool composites
EN
The aim of work is the investigation of the internal stresses in PVD coated metal matrix composites (MMC). Sintered MMC substrate is composed of the matrix with the chemical composition corresponding to the high-speed steel, reinforced with the TiC type hard carbide phase. Functionally graded composition of MMC providing of high ductility characteristic of steel in the core zone as well as high hardness characteristic of cemented carbides in the surface zone. Internal stresses were determined with use of finite element method in ANSYS environment. The reason of undertaking the work is necessity of develop the research of internal stresses, occurring in the coating, as well as in the adhesion zone of coating and substrate, which makes it possible to draw valuable conclusions concerning engineering process of the advisable structure and chemical composition of coatings. The investigations were carried out on cutting tools models containing defined zones differing in chemical composition. Modelled materials were characteristic of chemical composition corresponding to the high-speed steel at the core, reinforced with the TiC type hard carbide phase with the growing fraction of these phases in the outward direction from the core to the surface, additionally coated with (Ti,Al)N or Ti(C.N) functionally graded PVD coatings. Results of determined internal stresses were compared with the results calculated using experimental X-ray sin2ψ method. It was demonstrated, that the presented model meets the initial criteria, which gives ground to the assumption about its utility for determining the stresses in coatings as well as in functionally graded sintered materials. The results of computer simulations correlate with the experimental results.
EN
The paper presents the influence of mechanical surface damage on the physicochemical properties of plates after implantation made of CrNiMo stainless steel, used in the treatment of anterior surface deformity of the chest. Analysis of the data allowed us to investigate the effect of implant design and condition of their surface on the results of chest deformation treatment. Results of electrochemical, impedance and surface wettability tests and SEM observations were compared with clinical observations. When removing the plates we found only slight inflammatory-periosteal reactions. On the basis of obtained results, it can be stated that plates, in spite of mechanical damage of the surface, were characterized by good corrosion resistance, a fact which is confirmed by the results of clinical evaluation.
EN
The aim of this article of this paper is to present issues related to characterization of nanometric-sized carbides, nitrides and/or carbonitrides formed during tempering of carbide-steel cermets. Closer examination of those materials is important because of hardness growth of carbide-steel cermet after tempering. The results obtained during research show that the upswing of hardness is significantly higher than for high-speed steels. Another interesting fact is the displacement of secondary hardness effect observed for this material to a higher tempering temperature range. Determined influence of the atmosphere in the sintering process on precipitations formed during tempering of carbide-steel cermets. So far examination of carbidesteel cermet produced by powder injection moulding was carried out mainly in the scanning electron microscope. A proper description of nanosized particles is both important and difficult as achievements of nanoscience and nanotechnology confirm the significant influence of nanocrystalline particles on material properties even if its mass fraction is undetectable by standard methods. The following research studies have been carried out using transmission electron microscopy, mainly selected area electron diffraction and energy dispersive spectroscopy. The obtained results and computer simulations comparison were made.
13
Content available remote Metallographic research of selected alloys used in dentistry
EN
Purpose: The purpose of this article is to characterize and compare the metallic biomaterials used in dentistry and analyze their structure, properties and chemical composition. Design/methodology/approach:In the research a sample of the following materials was used: Modiral S (cobalt alloy), Heraenium NA (nickel alloy), ARGELOY NP BE-FREE (nickel alloy), ARGENCO 75 SA (gold alloy). Observations was made using a scanning electron microscope Zeiss Supra 35 using secondary electrons and backscattered electrons at the maximum magnification of 20000x. Chemical composition analysis was performed using the scattered X-radiation detector EDS. The research included taking a series of photos of the structure of metallic biomaterials using optical microscope MEF4A ANNIVERSARY. Photos were taken with magnification at 100x, 200x, 500x, 1000x. Hardness testing of various materials was performed using a Vickers hardness tester FM-700. Findings: Studies confirmed a typical dendritic structure for all the alloys. In the structures of the tested alloys compact pores and discontinuity of the structures were observed. On the basis of microhardness of alloys, cobalt alloys, nickel and gold alloy, it was found that cobalt alloy Modiral S has the highest hardness (400 HV). Practical implications: The structure and mechanical properties of alloys determine their particular usage and applications which is important in the selection of materials for specific applications. The Modiral S alloy is used in production of prostheses and combined works. In contrast: Heraenium NA, ARGENCO 75 SA and ARGELOY NP BE-FREE are used in production of dental crowns and bridges. Originality/value: Metal alloys used in dentistry have varying properties. The appropriate structure and mechanical properties of these alloys determine their specific use in dentistry.
EN
In this work the selected results of microstructure investigations and mechanical properties of the aluminium matrix composite materials reinforced with halloysite particles manufactured by powder metallurgy techniques, including mechanical milling and pressing and hot extrusion following them, are presented. Composite materials were elaborated employing the air atomized powders of aluminium alloy EN AWAlMg1SiCu as a matrix and the halloysite nanotubes as a reinforcement. Composite powders of aluminium alloy matrix reinforced with 5, 10 and 15 wt % of halloysite nanotubes were manufactured by high-energy ball milling using a planetary mill. The obtained composite powders were compacted in the cylindrical matrix of 25 mm in diameter with pressure of 300 MPa and then extruded at 480°C with caning and without degassing. The microstructure of the investigated material was examined by the light microscope and scanning and transmission electron microscope. To determine microhardness suitable tests were performed in the parallel plane related to the extrusion direction with a use of the Vickers hardness tester. The tests were also carry out to determine compressive strength static compression. It has been found that the process of low-energy agitation of the input powders causes relatively uneven distribution of irregular, mostly agglomerated reinforcement particles in the matrix. The composite materials produced in the process of high-energy grinding are characterized by a different structure: the halloysite reinforcement particles are very evenly distributed, rarely forming any agglomerations. The composite materials obtained as a result of mechanical synthesis and hot extrusion are characterized by the structure of evenly distributed, disperse mineral phase particles in fine-grain matrix of EN AW-AlMg1SiCu alloy, thus facilitating the obtainment of higher values of strength properties in comparison to the initial alloy. The nanostructural composite materials reinforced with halloysite particles with 15% mass share are characterized by more than 180% higher plasticity limit and almost twice higher microhardness in comparison to the matrix material.
PL
W pracy przedstawiono wybrane wyniki badań materiałów kompozytowych o osnowie stopu aluminium wzmacnianych cząstkami haloizytowymi wytworzonych z wykorzystaniem metod metalurgii proszków: mechanicznego mielenia oraz kolejno prasowania i wyciskania na gorąco. Badane materiały kompozytowe wytworzono z proszku stopu aluminium EN AW-AlMg1SiCu, stanowiącego materiał osnowy i wzmacnianego nanorurkami haloizytowymi. Do badań przygotowano trzy zestawy próbek zawierających odpowiednio 5, 10 i 15% masowo cząstek wzmacniających, mielonych w wysokoenergetycznym młynie kulowym. Proszki kompozytowe otrzymane w procesie mechanicznego mielenia sprasowano na zimno za pomocą prasy hydraulicznej w formie o średnicy 25 mm pod ciśnieniem 300 MPa, a następnie wyciskano w temperaturze 480°C bez odgazowania, w koszulce osłonowej. Strukturę opracowanych materiałów kompozytowych zbadano za pomocą mikroskopii świetlnej, a także skaningowej i transmisyjnej mikroskopii elektronowej. Sposobem Vickersa zmierzono twardość wyciskanych materiałów kompozytowych na zgładach poprzecznych, a na uniwersalnej maszynie wytrzymałościowej wykonano badania wytrzymałości na ściskanie. W celu oceny wpływu oddziaływania procesu mechanicznego mielenia proszków wyjściowych na własności badanych materiałów kompozytowych w porównaniu z procesem mieszania tych samych proszków zastosowano dwa rodzaje procesu mielenia. Stwierdzono, że proces niskoenergetycznego mieszania proszków wyjściowych powoduje stosunkowo nierównomierne rozłożenie nieregularnych, w większości zaglomerowanych cząstek wzmocnienia w metalowej osnowie. Odmienną strukturą cechują się materiały kompozytowe wytworzone w procesie wysokoenergetycznego mielenia: haloizytowe cząstki wzmacniające są rozłożone bardzo równomiernie, rzadko tworząc skupiska. Otrzymane w procesie mechanicznej syntezy i wyciskania na gorąco materiały kompozytowe charakteryzują się strukturą równomiernie rozłożonych, rozdrobnionych cząstek fazy mineralnej w drobnoziarnistej osnowie stopu EN AW-AlMg1SiCu, sprzyjającą osiąganiu wyższych wartości własności wytrzymałościowych w porównaniu ze stopem wyjściowym. Wytworzone nanostrukturalne materiały kompozytowe wzmacniane cząstkami haloizytowymi o udziale masowym 15% charakteryzują się w porównaniu z materiałem osnowy większą o ponad 180% granicą plastyczności oraz ponad dwukrotnie większą mikrotwardością.
PL
Celem badań było opracowanie materiałów narzędziowych będących wynikiem koncepcji połączenia inżynierii powierzchni jako dziedziny wiedzy i technologii jaką jest metalurgia proszków. Wynikiem tego są wytworzone materiały o gradientowych, węglikostalowych warstwach powierzchniowych na podłożu stalowym, łączące wykluczające się własności mechaniczne, takie jak duża twardość warstwy powierzchniowej i ciągliwość narzędzia. Do wytworzenia materiałów zastosowano techniki formowania proszków, z których autorska metoda formowania bezciśnieniowgo jest najlepsza ze względu na własności gotowego narzędzia. Opracowanie i zastosowanie nowej technologii formownia bezciśnieniowego jest możliwe dzięki wyjaśnieniu wpływu polimerowego lepiszcza stosowanego w nowoczesnych metodach formowania proszków oraz węgla pochodzącego z jego degradacji na aktywację procesu spiekania. Możliwość zastosowania nowoczesnych technik formowania proszków, w szczególności techniki formowania bezciśnieniowego powłok, została oceniona na podstawie analizy kompleksowych badań, począwszy od doboru składników, warunków homogenizacji mieszaniny, formowania i degradacji lepiszcza, a także przemian strukturalnych podczas spiekania oraz obróbki cieplnej. Przewiduje się, że opracowane i wytworzone materiały narzędziowe nowej generacji wypełnią lukę pod względem własności mechanicznych pomiędzy relatywnie ciągliwymi stalami szybkotnącymi i kruchymi węglikami spiekanymi. Nowo opracowana metoda może być wykorzystana w warunkach produkcji masowej lub jednostkowej, pozwalającej na przykład na regenerację zużytych powierzchni kosztownych narzędzi. Możliwości aplikacyjne technik formowania proszków do wytwarzania materiałów lub jedynie węglikostalowych warstw powierzchniowych o strukturze gradientowej są szersze niż tylko do materiałów narzędziowych. Otrzymane rozwiązania mogą mieć również zastosowanie w odniesieniu do elementów maszyn i urządzeń pracujących w warunkach zużycia ściernego.
EN
The goal of this investigations was development of the tool materials being the outcome of the concept of merging the surface engineering as the domain of knowledge with technology which is the powder metallurgy. The result are the fabricated materials with the gradient, cermet surface layers on steel substrate, combining the mutually exclusive mechanical properties like the high surface hardness and ductility of a tool. The powder forming techniques were used for fabrication of the materials, out from which the authorial pressureless forming method is the best one, owing to properties of the completed tool. Development and implementation of the new pressureless forming method is possible thanks to elucidation of the effect of the polymer binding agent used in the contemporary powder forming methods and carbon from its degradation on activation of the sintering process. Feasibility of employing the modern powder forming methods, and especially of the pressureless coatings forming technique, was assessed based on analysis of the complex technological tests, including selection of components, conditions of mix homogenisation conditions, forming, and binding agent degradation, and also investigation of the structural transformations during sintering and heat treatment. It is anticipated that the worked out and fabricated tool materials of the new generation will fill a gap in respect of the mechanical properties between the relatively ductile high-speed steels and the brittle sintered carbides. The newly developed method may be used in the mass- or piece production conditions making, e.g., regeneration possible of the costly tools’ surfaces. The application potential of the powders forming techniques for constituting materials or only cermet surface layers with the gradient structure seems to be more extensive than for the tool materials alone. The solutions obtained may also find applications for elements of machines and equipment operated in the abrasion wear conditions.
PL
Opisano wyniki badań struktury i właściwości warstw wierzchnich kompozytowych Ti/TiN wytwarzanych " in situ" w wyniku przetapiania warstwy wierzchniej płytki ze stopu tytanu Ti6Al4V wiązką lasera diodowego dużej mocy w atmosferze czystego azotu (azotowania laserowego gazowego). Analizowano wpływ parametrów procesu azotowania laserowego na mikrostrukturę warstw wierzchnich, mikrotwardość, odporność na zużycie ścierne typu metal - metal oraz odporności na zużycie erozyjne przy różnych kątach padania erodentu.
EN
It has been described the results of testing of the structure and properties of surface Ti/TiN composite layers produced "in situ" in consequence of remelting of the surface layer of the Ti6Al4V titanium alloy plate by means of high power diode laser under pure nitrogen (laser gas nitriding). The influence of the parameters of the laser gas nitriding process on the microstructure of surface layers, microhardness, abrasive wear resistance of the metal-metal type and erosive wear resistance at different glancing angles of the erodent has been analyzed.
EN
Purpose: Results of the effect of thermomechanical processing conditions on the microstructure, mechanical properties and crack resistance are included in the present work. Conditions of forging with the method of thermo-mechanical treatment were developed basing on the analysis of precipitation kinetics of MX interstitial phases in a solid solution, plastometric examinations and investigations of the kinetics of undercooled austenite phase transformations. Design/methodology/approach: Light microscopy and transmission electron microscopy techniques were used to reveal the microstructure of samples obtained as a result of the thermomechanical forging. Mechanical properties and hardness tests as well as resistance to cracking using Charpy V samples at room and lowered temperature were carried out. Findings: Applied thermo-mechanical treatment allows obtaining fine-grained microstructure of austenite during hot-working and production of forged parts, which acquire advantageous set of mechanical properties and guaranteed crack resistance after controlled cooling from finishing plastic deformation temperature and successive tempering. Forgings produced with the method of thermo-mechanical treatment, consecutively subjected to tempering in the temperature range from 550 to 650°C, reveal the values of YS0.2
18
EN
Purpose: The present work describes fabrication of aluminium AlMg1SiCu matrix composite materials reinforced with halloysite nanotubes by powder metallurgy techniques and hot extrusion. Design/methodology/approach: Mechanical milling, compacting and hot extrusion successively are considering as a method for manufacturing metal composite powders with a controlled fine microstructure and enhanced mechanical properties. It is possible by the repeated welding and fracturing of powders particles mixture in a highly energetic ball mill. Findings: The milling process has a huge influence on the properties of powder materials, changing the spherical morphology of as-received powder during milling process to flattened one due to particle deformation followed by welding and fracturing particles of deformed and hardened enough which allows to receive equiaxial particles morphology again. The investigation shows that so called brittle mineral particles yields to plastic deformation as good as ductile aluminium alloy particles. That indicates that the halloysite powder can play a role of the accelerator during mechanical milling. High energy ball milling as a method of mechanical milling improves the distribution of the halloysite reinforcing particles throughout the aluminium matrix, simultaneously reducing the size of particles. The apparent density changes versus milling time can be used to control the composite powders production by mechanical milling and the presence of halloysite reinforcements particles accelerates the mechanical milling process. Research limitations/implications: Contributes to knowledge about technology, structure and properties of aluminium alloy matrix composite material reinforced with mineral nanoparticles. Practical implications: Conducted research shows that applied technology allows obtaining very good microstructural characteristics. Originality/value: It has been confirmed that halloysite nanotubes can be applied as an effective reinforcement in the aluminium matrix composites. Deformation, grain size reduction and dispersion conduce to hardening of the composite powders. Mechanical milling cause a high degree of deformation, decrease the grain size even to nanoscale and create an enormously uniform distribution of reinforcing phases or oxides in the structure of the metal.
EN
The scientific aim of the paper is the comparative analysis of the hot-working behaviour and microstructure evolution of thermomechanically processed and controlled cooled three advanced high-strength steels (AHSS) used in the automotive industry. The hot workability of three selected steel grades with a various content of Mn and C being major austenite-forming elements was compared. Evaluation of the resistance for hot deformation was carried out on a basis of continuous compression, double-hit compression, four-step compression and seven-step compression experiments simulating conditions similar to industrial processes. It was found that the hot workability of the new generation of AHSS is very challenging due to high values of flow stresses required. However, it is possible to obtain fine-grained transformation products of supercooled austenite with a high volume fraction of retained austenite for low-alloyed steels or single-phase austenitic microstructure in the high-manganese steel. Thermally activated processes of microstructure restoration which enable for successive grain refinement and affecting final flow stress values were identified. Finally, the comparison of the microstructures characterizing the first, second and third generation of AHSS was carried out. Some similarities and differences concerning the hot deformation behaviour and microstructure detailes are indicated.
PL
Celem naukowym pracy jest analiza porównawcza obróbki plastycznej na gorąco i rozwoju mikrostruktury obrobionych cieplno-plastycznie oraz chłodzonych w kontrolowanych warunkach trzech wysokowytrzymałych stali stosowanych w motoryzacji (AHSS). Przedstawiono porównanie odkształcalności na gorąco 3 wybranych gatunków stali o zróżnicowanej zawartości Mn i C, będących głównymi pierwiastkami austenitotwórczymi. Oceny oporu kształtowania plastycznego dokonano na podstawie prób ściskania ciągłego, ściskania dwuetapowego, cztero-etapowego oraz siedmioetapowego symulującego warunki zbliżone do procesów przemysłowych. Stwierdzono, że odkształcalność na gorąco nowej generacji stali AHSS wymaga zastosowania dużej wartości naprężeń uplastyczniających. Możliwe jest jednak uzyskanie drobnoziarnistych produktów przemiany austenitu przechłodzonego o dużym udziale austenitu szczątkowego w stalach niskostopowych lub jednorodnej strukturze austenitycznej w stali wysokomanganowej. Dokonano identyfikacji aktywowanych cieplnie procesów odbudowy mikrostruktury austenitu pozwalających na sukcesywne jego rozdrobnienie oraz decydujących o końcowej wartości naprężenia płynięcia. Porównano uzyskane mikrostruktury stali charakteryzujące pierwszą, drugą i trzecią generację stali AHSS. Wskazano podobieństwa i różnice dotyczące odkształcalności stali na gorąco oraz szczegółów mikrostrukturalnych.
20
Content available remote Polymer materials used in endodontic treatment - in vitro testing
EN
Purpose: The paper contains the characteristics of dental materials used for filling the dental root canal as well as presentation of their selection according to the criteria suggested Grossman. Furthermore the paper includes tests on the materials intended to fill the root canal selected according to their attractiveness matrix, while the in vitro tests comprised selection of the most effective material obturating the internal space of the root canal. The filling tightness was assumed to be the effectiveness measure, in other words, tight fusion of the filling material and the root canal wall. Design/methodology/approach: An attractiveness matrix was created for the materials used to fill the root canals, using the weighted scores method for the preference analysis. The two materials selected were subjected to materialographic tests by means of SUPRA 35, HD scanning microscope from Zeiss and Stereo Discovery V12 stereoscopic light microscope with AxioCam HRC digital camera from Zeiss. Findings: Based on the analysis of attractiveness matrix results of materials used for filling dental root canal, two materials have been selected for further tests: gutta-percha matrix and matrix of polyester polymer materials. The gutta-percha matrix is characterised with perfect properties, including without limitation strength and relatively high quality level of the obturation. The matrix of polyester polymer materials, in turn, has a lower strength and relatively high level of filling quality. As a result of materialographic tests it was found that the material on gutta-percha matrix thermoplastically applied into the canal, along with the polymer sealer, enables tight fusion of the obturation material and the root canal wall. Practical implications: The materialographic test results suggest that the most effective root canal obturation material, due to the tightest obturation achieved, is the gutta-percha matrix material applied along with a polymer sealer, thermoplastically applied into the canal. The endodontic procedure carried out in the above way enables avoiding the tooth extraction and enables prosthetic or composite restoration of the tooth crown on its own pillar and is responsible for the patient’s functionality, beauty care and health. Originality/value: The application of matrix analysis in the field of endodontics (usually applied to management education and other) for evaluation of materials intended to obturate root canals.
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