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Ferritic ODS steel elemental powder compositions with various Zr content (0.3–1.0 wt.%), ground in a Pulverisette 6 planetary ball mill, were extensively studied by X-ray diffraction line profile analysis, microscopic observations, microhardness testing and particle size measurements. A characteristic three-stage process of flattening the soft powders, formation of convoluted lamellae and, finally, formation of nanocrystalline grains was observed. In order to quantify the microstructural properties, expressed mainly in terms of crystallite size and dislocation density, a methodology for detailed and accurate microstructure analysis of nanosized and severely deformed materials was proposed by the Whole Powder Pattern Modelling (WPPM) approach. In the case of the proposed ODS alloy composition, the overlapping of Fe and Cr Bragg reflections makes the microstructure analysis certainly more complicated. The results showed that the microstructure of powders evolved towards the nanocrystalline state consisting of fine (diameter of ~15 nm) and narrowly dispersed domains, with extensive dislocation density exceeding 10 16 m−2. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) has seen remarkable development in recent years due to relatively high efficiency of the process. Cold spraying (CS) is a particular method of AM, in which titanium and titanium alloy powders are used. CS is a very competitive technology enabling the deposition of coatings, repairing machine parts, and manufacturing new components. For specific applications, the surface of cold-sprayed materials may require further processing. This paper reports an attempt to employ laser surface treatment (LST) of cold-sprayed coatings on an aluminium alloy substrate. The influence of laser beam interaction time on the coatings' properties was analysed. The microstructure was investigated and observed employing scanning electron microscopy (SEM). To evaluate residual stress after CS and LST, the sin2ψ technique was used. Investigations were also performed on Vickers hardness, contact angle, and surface roughness. Significant changes in the surface morphology of the coatings and elevated residual stress levels dependent on the laser beam interaction time were observed. Increased Vickers hardness was recorded for titanium alloy Ti6Al4V. LST also led to increased surface hydrophilicity of the modified materials Ti and Ti6Al4V. [ABSTRACT FROM AUTHOR]

The described method enables facile gram-scale preparation of CuFeS2 nanocrystals exhibiting interesting thermoelectric properties from simple and readily available precursors. Exchange of primary organic ligands for inorganic ones using either (NH4)2S or triethyloxonium tetrafuoroborate (Meerwein's salt) resulted in nanocrystals from which n-type bulk thermoelectric materials were obtained through sintering under pressure. The measured physical properties of the fabricated bulk thermoelectric materials depend on the type of inorganic ligands used for the exchange. In particular, materials that were surface-modified with Meerwein's salt have a higher Seebeck coefficient (|S| = 238 μV K-1) as compared to those modified with (NH4)2S, whereas the latter exhibit higher electrical conductivity (8500 S m-1) and lower thermal conductivity (0.5 W m-1 K-1), both of which are favorable for thermoelectric applications. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) and its alloys offer promise for aerospace, railway, and 3D technology applications, yet their inherent limitations, including inadequate strength, pose challenges. Magnesium matrix composites, particularly with metallic reinforcements like titanium (Ti) and its alloys, present a viable solution. Therefore, this study investigates the impact of Ti6Al4V reinforcement on AZ31 magnesium alloy composites produced using pulse plasma sintering (PPS). Results show enhanced microhardness of the materials due to improved densification and microstructural refinement. However, Ti6Al4V addition decreased corrosion resistance, leading to strong microgalvanic corrosion and substrate dissolution. Understanding these effects is crucial for designing Mg-based materials for industries like petrochemicals, where degradation-resistant materials are vital for high-pressure environments. This research provides valuable insights into developing Mg-Ti6Al4V composites with tailored properties for diverse industrial applications, highlighting the importance of considering corrosion behavior in material design. Further investigation is warranted to establish predictive correlations between Ti6Al4V content and corrosion rate for optimizing composite performance. [ABSTRACT FROM AUTHOR]

Thermoelectric materials (GeTe) 100−x (AgSbTe 2) x , or TAGS, are known materials for middle-temperature range applications, because of their very good electrical and thermal properties. A GeTe-based TAGS material exhibits high thermal and electrical conductivity but its Seebeck coefficient is too low and can be optimized by optimal doping. One of the methods to decrease thermal conductivity is nano-structurization by introducing nano AgSbTe 2 inclusions into the matrix, however, that will also interfere with other thermoelectric properties. The influence of AgSbSe 2 addition on thermoelectric properties was analysed. For the purpose of this work AgSbSe 2 , AgSbTe 2 , GeTe and compositions (GeTe) 75 (AgSbTe 2) y (AgSbSe 2) x was synthesised, where x + y = 25 and y = (0, 0.26; 0.51, 1.25, 6.25). This paper describes the preparation and thermoelectric properties of materials, consolidated by rapid Spark Plasma Sintering (SPS). For optimally doped TAGS-75 with the addition of AgSbSe 2 (y = 1.25), the stabilization of the cubic structure was obtained, an increase of Seebeck coefficient by about 50% (from 50 to 100 μVK−1 at 325 K), thermal conductivity decrease by 20% (from 1.2 to 0.95 Wm−1K−1 at 325 K), electrical conductivity decrease by about 50% (1.8 ×105 to 9 ×104 Sm−1). Finally, the thermoelectric figure dimensionless of merit ZT increased by about 40% (323–625 K) and its maximum value reached ZT = 1.2 (at 625 K) for optimally doped material, while 0.7 at 625 K for undoped TAGS-75. • Review of TAGS thermoelectric materials. • TE intermetallic nanomaterials, sintered by Spark Plasma Sintering (SPS). • New TE materials composition, based on: AgSbTe2, AgSbSe2 synthesized with GeTe. • Approaches for new type TEGs components. [ABSTRACT FROM AUTHOR]

The interest in the Spark Plasma Sintering (SPS) technique has continuously increased over the last few years. This article shows the possibility of the development of an SPS device used for material processing and synthesis in both scientific and industrial applications and aims to present manufacturing methods and the versatility of an SPS device, presenting examples of processing Arc-Melted- (half-Heusler, cobalt triantimonide) and Self-propagating High-temperature Synthesis (SHS)-synthesized semiconductor (bismuth telluride) materials. The SPS system functionality development is presented, the purpose of which was to broaden the knowledge of the nature of SPS processes. This approach enabled the precise design of material sintering processes and also contributed to increasing the repeatability and accuracy of sintering conditions. [ABSTRACT FROM AUTHOR]

Zirconia is commonly used for manufacturing of dental implants thanks to its excellent mechanical, biological and aesthetic properties. However, its bioinertness inhibits bonding with the surrounding hard tissue and other surface interactions. In our study, we present a method for multifunctionalization of zirconia surface to improve its osseointegration and to minimize the infection risks. For this reason, we introduced antibacterial and bioactive properties to zirconia surfaces by calcium phosphate biomimetic coating. The samples were incubated in vials in horizontal and vertical position in concentrated simulated body fluid (SBF) containing 0.1, 0.5, and 3 g/L of silver nanoparticles (Ag-NPs) and then were tested for their structure, surface properties, cytocompatibility and antibacterial properties. The results demonstrated that our method is suitable to introduce Ag-NPs at different concentrations into the calcium phosphate layer, i.e. from 0.05–26.6 atom% as shown by EDX. According to the results of CFU-assay these coatings exhibited antibacterial properties against S. aureus and E. coli in correlation with the concentration of Ag-NP. The potential cytotoxicity of the coated samples was determined by AlamarBlue® assay and live/dead staining of MG63 osteoblast-like cells in direct contact and by testing the extracts from the materials. Only samples containing 0.05 atom% Ag-NPs, i.e. incubated in vertical position at SBF with 0.01 g/L Ag-NPs, were found cytocompatible in direct contact with MG63 cells. On the contrary in the indirect tests, the extracts from all the materials were found cytocompatible. This method could allow developing the completely new material group, exhibiting not only one but several biological properties, which can improve osseointegration and minimize infection risks. [ABSTRACT FROM AUTHOR]

Cytocompatibility and hemocompatibility are essential features for tissue- and blood-contacting implants such as artificial heart valves, vascular grafts and stents. Platelet activation as the main trigger of thrombosis results in implant failures. The purpose of this study results from the demands on anti-coagulant and non-corrosive innovative biomaterials for cardiovascular implants. Therefore, hemocompatibility and cytocompatibility of various high-strength ceramics, such as alumina, zirconia, silicon nitride and silicon carbide, were examined to identify the most appropriate ceramic for cardiovascular implants. In addition to the material species, different crystallographic structures (single- and poly-crystalline) and surface terminations (Si and C faces) of silicon carbide were used in order to reveal the interactions between blood and material surface. Three cell types, i.e. human umbilical vein endothelial cells, mesenchymal stem cells and blood cells, were cultured on the substrates and their interactions with material surfaces were analyzed. Cytotoxicity of the materials was tested by live/dead staining. Hemocompatibility in terms of platelet and white blood cell activation was examined via scanning electron microscopy and indirect ELISA. To mimic physiological conditions in vitro, the hemocompatibility of the materials was additionally analyzed in a bioreactor under dynamic flow conditions in comparison to static incubation. All ceramics were found to be cytocompatible for mesenchymal stem cells, human umbilical vein endothelial cells and blood cells. The highest number of resting, non-activated platelets was observed on the monocrystalline silicon carbide demonstrating that this material triggers the platelet activation less compared to the other materials. It is found to be the most appropriate ceramic for blood-contacting implants in terms of cell adhesion, cell viability, and hemocompatibility. [ABSTRACT FROM AUTHOR]

This article discusses the morphology and thermomechanical properties of graphene oxide (GO) paper sheets and GO paper composites reinforced with carbon fibers. GO paper was fabricated using GO paste obtained by the condensation of GO aqueous solution synthesized using the Hummers' method. Carbon fibers were implemented to improve the mechanical properties of the pristine GO paper. All the investigated papers were subjected to thermal treatment to check thermo-related morphological and mechanical properties. The results presented in this study allowed for the deeper insight into morphological, structural, and mechanical volume and surface-related properties of pristine GO and GO-based composite materials reinforced with carbon fibers. We showed that there are two important factors that should be taken into consideration for the design and fabrication of GO-based papers. These factors were the concentration of the reinforcing agent and the thermal reduction of the papers. Both factors have influenced the final properties of the resulting GO-based papers. For the first time, it was revealed how the addition of the reinforcing material affects the GO paper thermal expansion coefficient. [Display omitted] [ABSTRACT FROM AUTHOR]

High temperature corrosion of thermoelectric materials is one of the most important issues linked with their application for power generation, especially in terrestrial conditions. The high chemical affinity of elements composing thermoelectric material to oxygen results in continuous degradation at high temperatures of most state-of-the-art materials. This issue is also well recognized in the case of antimonide skutterudites. The simplest way to protect against this process is the use of coatings. Complicated geometry of thermoelectric module favors coatings that can be deposited in a simple way on an assembled module. Such an opportunity, besides good thermal stability and appropriate thermal and electrical properties, is provided by amorphous silicon oxycarbide Si-O-C coatings. In this work, the results on Si-O-C coatings deposited on In0.4Co4Sb12 skutterudite are presented. The influence of heat treatment temperature and substrate roughness on the deposited layer is shown. Protective properties of the Si-O-C layer are presented by comparison of electrical conductivity and Seebeck coefficient of coated and uncoated samples, before and after isothermal oxidation in air at 430 °C for 24 h. In such conditions, the uncoated samples are distinctly oxidized (weight gain of 2.4%) with strongly affected electrical properties, while the coated samples show a slight weight gain of 0.1% and almost unchanged electrical properties. [ABSTRACT FROM AUTHOR]

Doping is one of the possible ways to significantly increase the thermoelectric properties of many different materials. It has been confirmed that by introducing bismuth atoms into Mg sites in the Mg2Si compound, it is possible to increase career concentration and intensify the effect of phonon scattering, which results in remarkable enhancement in the figure of merit (ZT) value. Magnesium silicide has gained scientists’ attention due to its nontoxicity, low density, and inexpensiveness. This paper reports on our latest attempt to employ ultrafast self-propagating high-temperature synthesis (SHS) followed by the spark plasma sintering (SPS) as a synthesis process of doped Mg2Si. Materials with varied bismuth doping were fabricated and then thoroughly analyzed with the laser flash method (LFA), X-ray diffraction (XRD), scanning electron microscopy (SEM) with an integrated energy-dispersive spectrometer (EDS). For density measurement, the Archimedes method was used. The electrical conductivity was measured using a standard four-probe method. The See-beck coefficient was calculated from measured See-beck voltage in the sample subjected to a temperature gradient. The structural analyses showed the Mg2Si phase as dominant and Bi2Mg3 located at grain boundaries. Bismuth doping enhanced ZT for every dopant concentration. ZT = 0.44 and ZT=0.38 were obtained for 3wt% and 2wt% at 770 K, respectively [ABSTRACT FROM AUTHOR]

We report on the generation of 152-nJ Q-switched pulses in all-polarization-maintaining Er-doped fiber laser. The laser is passively modulated by the antimony telluride (Sb2Te3) layer sputtered on a surface of the side-polished fiber in order to exploit the evanescent field interaction in optically nonlinear material. The laser cavity is designed in an extremely simple way comprising, in addition to fibers, only one component and the saturable absorber, forming a robust, compact, and stable source of short pulses. The repetition rate might be tuned from 42 kHz up to 132 kHz. The shortest recorded pulse duration was the 857 ns. [ABSTRACT FROM AUTHOR]

[Display omitted] • GO can functionalize inert zirconia surfaces by covalent immobilization. • GO nanofilm provides wettability and osteogenic character to zirconia implants. • GO coating on bioinert ceramics improves osteogenic differentiation of MSC. • Novel GO-film is full-covering, homogeneous, hydrophilic, and hydrolytically stable. This study aimed to join the proven osteogenic properties of graphene oxide (GO) with bioinert zirconia implants. The dip-coating technique allows achieving this goal by forming a thin, homogenous, hydrolytically, and mechanically stable GO film onto silanized ceramic-substrates. SEM, AFM, XPS, and contact angle measurements confirmed the presence, transparency, integrity, and homogenous covering character of the GO film. The GO film is hydrolytically stable since it remained intact after a soaking period of 24 days in double-distilled water (ddH 2 O) and phosphate buffered saline and resisted a ten-minute sonication treatment for in ddH 2 O. This strong hydrolytic stability is due to the silanization with 3-amino-propyl-diisopropylethoxy-silane (APDS) enhancing the anchoring of GO flakes onto zirconia surfaces. Besides, the GO film disinfectable in 70% ethanol. Subsequently, we assessed our immobilized GO film as cytocompatible for L929 mouse fibroblast and human mesenchymal stem cells and propitious for the osteogenic differentiation demonstrated by a two times upregulation of the osteogenic transcription factor RunX2. The active hydroxyl and carboxyl groups of the GO film open new perspectives for the functionalization of ceramic implants by immobilization of biological agents, such as growth factors or antibiotics, and thus enhance the osseointegration. [ABSTRACT FROM AUTHOR]