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The present work aims at the preparation and characterization of ceramic layered composite prepared from fine submicron-sized Al2O3 with the addition of electrospun graphene-coated Al2O3 fibers (Al2O3/G-Fs) by Spark Plasma Sintering with double pressure sintering process. A layered composite containing 2.5 wt. % of Al2O3/G fibers in three homogeneous layers was prepared and compared with the pure monolithic Al2O3 material obtained under the same conditions. The microstructures of the samples were studied by optical microscopy, scanning, and transmission electron microscopy. The presence of graphene after the sintering in the final composite was proved by Raman spectroscopy. The effect of the graphene-coated fibers on the composite`s microstructure and mechanical properties was described along with the fractographic analysis. Graphene on the surface of the electrospun Al2O3 fibers suppressed the grain growth which dominantly takes place during the sintering of the composite, which significantly influenced the character of the fracture. While predominantly intergranular fracture occurs in the monolithic fracture surface, the fracture character becomes transgranular with the addition of layers of Al2O3/G-Fs. Fracture toughness improvement took place because of the presence of small pores, in order of a few nanometers, which showed high energy absorption and provided self-induced crack propagation inhibition.

SnO2 is an n-type semiconductor with the band gap energy of 3.6 eV. It has been widely studied for gas sensing applications, the sensitivity of which can be easily tuned by the operating temperature. The presented paper is focused on the preparation and detailed characterization of the hollow SnO2 nano/microfibers suitable for gas detection sensors. Ceramic SnO2 fibers were produced by needleless electrospinning and followed by the calcination process. The characterization was performed by SEM, TEM, XRD, and Raman spectroscopy. The precursor PVP/SnO2 fibers had amorphous nature. The calcination of the electro spun precursor resulted in the formation of hollow crystalline fibrous structures. The formation mechanism of hollow fibers has been described. Subsequently, a homogeneous fibrous layer was created by the spin coating method for gas sensing applications.

Polymer-coated metals may act as biodegradable orthopedic implants with adjustable corrosion rates. Metallic surfaces represent a dynamic system with specific interactions occurring after the material is implanted into the human body. An additional layer, in the form of polymeric thin film, changes the nature of this metal-body fluids interface. Moreover, the interaction between polymer and metal itself can differ for various systems. Iron-based material modified with a thin layer of polyethyleneimine (PEI) coating was prepared and studied as potential absorbable implant. Computational methods were employed to study the interaction between the metallic surface and polymer functional monomer units at atomic levels. Various spectroscopical and optical methods (SEM, AFM, Confocal, and Raman spectroscopy) were also used to characterize prepared material. Electrochemical measurements have been chosen to study the polymer adsorption process onto the iron surface and corrosion behavior which is greatly influenced by the PEI presence. The adsorption mechanism of PEI onto iron was proposed alongside the evaluation of Fe and Fe-PEI degradation behavior studied using the impedance method. Bonding via amino -NH2 group of PEI onto Fe and enhanced corrosion rate of coated samples were observed and confirmed.

The wear resistance and tribological characteristics of spark plasma sintered ZrB2 + B4C, ZrB2 + SiC and ZrB2 + ZrC composites were investigated under dry sliding conditions at applied loads of 5 N and 50 N in air. The microstructure, deformation and damage characteristics were studied using scanning electron microscopy, confocal electron microscopy, a focused ion beam and atomic force microscopy. The friction coefficient values were very similar for all composites with values ranging from 0.63 to 0.72 and with the lowest value recorded for the ZrB2 + SiC composite at a 5 N applied load. The ZrB2 + ZrC composite was the most wear resistant, with wear rates at a 5 N load of 6.15 × 10−6 mm3/(N·m) and at a 50 N of 7.3 × 10−6 mm3/(N·m). None, or a very limited number of grain pull-outs and/or lateral fractures of grains were found during the wear tests. At the 5 N load, abrasive grooves connected with deformations and Hertzian crack formations were the main wear mechanisms in all systems, with limited crack formations in the ZrB2 + ZrC composite. Tribofilm formations connected with debris origin, oxidation and tribochemical reactions were dominant in all composites, with similar chemical compositions but different sizes and thicknesses at the 50 N load.

Nano/microfibers are already widely used as the reinforcements in various types of advanced composites for reducing weight, improving specific properties like hardness, fracture toughness and other mechanical ones. This contribution describes the preparation of the titanium dioxide nano/microfibers by needle-less electrospinning, along with a detailed characterization of the obtained polycrystalline ceramics. For spinning solutions preparation the polyvinylpyrrolidone (PVP), titanium isopropoxide (TTIP), ethanol and acetic acid were used. Influence of the ceramic precursor concentration in the spinning solution showed that decreasing the concentration of TTIP from 30 to 10 wt.% has no effect on the precursor polymer fibers shape. However, it causes deviation from the fibers oval shape (in the cross-section) up to the formation of solid ribbons or even multilayered porous ribbons. Heat treatment temperature defined the phase composition of the obtained oxide ceramics – stabile polycrystalline rutile fibers were obtained at 600 °C.

The wear resistance and tribological characteristics of alumina/graphene layered and fiber-reinforced composites were investigated under dry sliding conditions at applied loads of 10 N and 50 N in the air. The experimental materials were prepared by a combination of electrospinning-calcination-chemical vapor deposition and spark plasma sintering. Graphene-coated Al2O3 microfibers were used to form layers in layered monolithic alumina/graphene-coated Al2O3 microfibers composite, and as reinforcements for the alumina matrix in the fiber-reinforced composite. The microstructure, deformation, and damage characteristics were studied. Both composites show a lower coefficient of friction in comparison to alumina with the lowest value of 0.42 for the fiber-reinforced composite measured at a load of 10 N. At the load of 10 N the composites exhibit very high wear resistance with values of wear rate 2.78 × 10−8mm3/(N·m) for the layered and 1.74 × 10−8mm3/(N·m) for the fiber-reinforced composite, in comparison to the wear rate of Al2O3 with a value of 5.35 × 10−6mm3/(N·m). The significant improvement in the wear resistance of the composites was associated with the improved mechanical properties and formation of a protective tribofilm on the wear tracks by the multilayered graphene present on the surface of Al2O3 microfibers and alumina debris, which provided the lubricating effect for the composites.

Electrospinning is a versatile and flexible technique for the preparation of ultrafine fibers. The present study aims to provide a comprehensive overview of electrospinning, as a complex technique, its evolution toward the high-throughput techniques, including the basic principles, parameters influencing the fibers production process, methods applied to solve the alignment difficulties, commonly used polymers and solvents, and the applications of the electrospun materials. We begin with an insight into the history of electrospinning, followed by its theoretical background and typical apparatus. Then, its renaissance over the past two decades as a powerful technology for the production of nanofibers suitable for industrial scale is presented. Afterward, we briefly discuss the applications of electrospun fibers, including use in different fields of industry, energy harvesting/conversion/storage, photonic and electronic devices, as well as biomedical applications. In the end, we also offer perspectives on the challenges and new directions for developments in electrospinning.

Deep eutectic solvents (DES) are formed by an acceptor and a donor of hydrogen bonds. They are generally considered as a possible alternative to hazardous organic solvents in various fields. Very recently they have also appeared in analytical chemistry, used mainly for the separation of analytes before instrumental quantification. For the development of new extraction procedures, it is important, among other things, to understand the mechanism of the extraction process itself. In this study we present NMR, IR and Raman spectroscopy studies of TBAB-Gly-based DESs at various HBA:HBD molar ratios for the neat DES as well as the DES mixed with various amounts of added water to better understand the mechanism of DES formation, intermolecular interactions in DES and the interaction of the DES with water, which have not yet been studied in detail. The obtained results indicate that hydrogen bonds between TBAB and Gly exist in the DESs at all molar ratios (1:2; 1:3; 1:4). A small amount of water added to the DES structure provides the establishment of an H-bond network, which does not weaken the existing H-bonds between the HBA and HBD, thus creating a stable supramolecular structure. However, further increasing of water amount provide to weakened of hydrogen bonds between TBAB and Gly.

Titanium metal covered with titanium dioxide (Ti/TiO2) was used as a promising non-enzymatic glucose sensor demonstrating a new approach to electrochemical glucose determination. A Ti/TiO2 nanotubes-glucose complex formation on an electrode surface was demonstrated by infrared, Raman, and X-ray photoelectron spectroscopy. The main electrochemical method used for glucose detection was electrochemical impedance spectroscopy as a promising method for an easy electrochemical determination. To the best of our knowledge, this kind of sensor has never been studied especially in case of non-enzymatic glucose detection. Ti/TiO2 glucose sensor displays a wide practical linear range (1–15 mM) in a pH neutral condition, which cover the typical range in diabetic patients. The selectivity and the limit of detection were 8.3 kΩ·mM−1 and 1.2 mM, respectively. Therefore this kind of a system is very promising candidate for blood glucose sensing which should be able to replace enzymatic glucose sensors. Based on the properties of the prepared sensors, TiO2 is an unrivalled material for glucose sensing comparable with the enzymatic sensors.

Bioresorbable biomaterials are expected to degrade or to be resorbed within the body at an appropriate degradation rate rather than removing the implant after fulfilling its function. Adsorption of proteins on the metal surface and its subsequent detachment can affect the degradation mechanism and induce health complications. The iron samples were produced from carbonyl iron powder by powder metallurgy and coated by thin layer of polyethyleneimine (PEI). The effect of both PEI coating and bovine serum albumin (BSA) interaction on corrosion resistance of iron biomaterials in Hanks’ solution was investigated. Adsorption of BSA onto Fe + PEI was more rapid in comparison to adsorption onto bare Fe due to the electrostatic nature of BSA adsorption to polymeric layer. The corrosion behavior of sintered samples in Hanks’ solution without and with protein was investigated. Alteration of degradation mechanism was observed in the presence of PEI and/or BSA. PEI was observed to avoid the pitting corrosion while presence of BSA resulted in surface-induced complexation. The extensive pitting with high extent of metal release was observed in the presence of PEI and BSA. The additional spectroscopic and microscopic methods were used to prove the suggested alteration of corrosion mechanism.