The technique of electrospinning was employed to fabricate uniform one-dimensional inorganic-organic composite nanofibers at room temperature from a solution containing equal volumes of aluminum 2, 4-pentanedionate in acetone and polyvinylpyrrolidone in ethanol. Upon firing and sintering under carefully pre-selected time-temperature profiles (heating rate, temperature and soak time), high-purity and crystalline alumina nanofibers retaining the original morphological features present in the as-spun composite (cermer) fibers were obtained. Tools such as laser Raman spectroscopy, scanning and transmission electron microscopy together with energy dispersive spectroscopy and selected area electron diffraction were employed to follow
the systematic evolution of the ceramic phase and its morphological features in the as-spun and the fired fibers. X-ray diffraction was used to identify the crystalline fate of the final product.
An equiatomic multi-component alloy Ni20Ti20Ta20Co20Cu20 (at. %) was obtained using vacuum arc melting. In order to characterize such an alloy, microstructure analysis has been performed using Scanning and Transmission Electron Microscopy, Electron Backscattered Diffraction, X-ray Diffraction and Energy Dispersive X-ray Spectroscopy techniques. Microstructure analysis revealed the presence of one rhombohedral and two cubic phases. Energy Dispersive X-ray Spectroscopy measurements revealed that both observed phases include five chemical elements in the structure. Using Rietveld refinement approach the lattice parameters were refined for the observed phases.
A new NiTi-based multi-component Ni35Ti35Ta10Co10Cu10 (at.%) alloy was obtained by vacuum arc melting. The microstructure of the alloy has been studied using scanning and transmission electron microscopy, backscatter electron diffraction and X-ray diffraction techniques. The performed measurements showed presence of two cubic and one tetragonal phases. Energy dispersive X-ray spectroscopy analysis confirmed that all the observed phases contained all five principal elements.
The present research is focused on the characterization of the composites from Al2O3-Cu-Ni system. Two methods of ceramic-metal composite forming were applied: uniaxial powder pressing and Pulse Plasma Sintering (PPS). To obtain the samples the powder mixtures containing 85 vol.% of Al2O3 and 15 vol.% of metal powders were used. Influence of the sintering process on microstructure and mechanical properties of the two series of the composites was analyzed in detail. The selected physical properties of samples were characterized by Archimedes immersion method. Vickers hardness and the fracture toughness of the composites was determined as well. The microstructure of the composites was characterized by XRD, SEM, EDX. Fractography investigation was carried out as well. Independently on composite production method Al2O3, Cu, Ni, and CuNi phases were revealed. Fractography investigation results revealed different character of fracture in dependence of fabrication method. Pulse Plasma Sintered samples were characterized by higher crack resistance and higher Vickers hardness in comparison to the specimens manufactured by uniaxial pressing.
In this work, vacuum hot pressed Ni-Mn-Sn-In Heusler alloys with different concentration of In (0, 2 and 4 at.%), were investigated. The magneto-structural behaviour and microstructure dependencies on chemical composition and on heat treatment were examined. It was found that the martensite start transformation temperature increases with growing In content and to a lesser extent with increasing temperature of heat treatment. The high energy X-ray synchrotron radiation results, demonstrated that both chemical composition as well as temperature of heat treatment slightly modified the crystal structures of the studied alloys. Microstructural investigation performed by transmission electron microscopy confirmed chemical composition and crystal structure changes in the alloys.
The knowledge whether and how chemical species react with tissues is important because of protection against harmful factors, diagnose of dermatological diseases, validation of dermatological procedures as well as effectiveness of topical therapies. In presented work the effects of chemical agents on plates of human fingernails were studied using Atomic Force Microscopy and Scanning Electron Microscopy. Apart from that, mapping of the elastic properties of the nails was also carried out. To obtain reliable measures of spatial evolution of the surface variations, recorded images were analyzed in terms of scaling invariance brought by fractal geometry, instead of common though not unique statistical measures.
The aim of this work was to investigate the possibility of obtaining an amorphous/crystalline composite starting from Ni-Si- B-based powder grade 1559-40 and silver powder. The alloy was produced using arc melting of 95% wt. Ni-Si-B-based powder (1559-40) and 5% wt. Ag powder. Ingot was re-melted on a copper plate and observed while cooling using a mid-wave infra-red camera. The alloy was then melt-spun in a helium atmosphere. The microstructure of the ingot as well as the melt-spun ribbon was studied using light microscopy and scanning electron microscopy with energy dispersive spectrometry. Phase identification was performed by means of X-ray diffraction. The observations confirmed an amorphous/crystalline microstructure of the ribbon where the predominant constituent of the microstructure was an amorphous phase enriched with Ni, Si, and B, while the minor constituent was an Ag-rich crystalline phase distributed in a film along the melt-spinning direction.
The present work focuses on the fabrication of glass fiber and multifilament discarded fishnet nylon fiber polymer composites with four different fiber compositions. Composites are molded by means of simple hand lay-up methodology with dissimilar layers of the fiber mat. The mechanical characterization (tensile and impact) and thermal analysis of composites have to be investigated. Among the different patterns, hybrid composites reflected better tensile and impact properties as compared to the conventional materials. Morphological characterization was carried out to figure out the de-bonding of fiber/matrix adhesion characteristics of fractured face of tensile testing samples. The result suggests the potential for reuse of discarded fishnet, which constitutes a better alternative for structural work and for possible applications to be used to develop added-value products.