Nanomaterials & Nanotechnology
Miranda Benavides; Denis Leonardo Mayta; Fernando Alonso Cuzziramos; Gerhard Paul Rodriguez; Fredy Alberto Huaman-Mamani
Abstract
The traditional method of manufacturing SiC compounds is associated with a serious environmental problem, mainly due to the need for large amounts of energy (generally derived from oil) to reach processing temperatures (typically above 2500 ºC). In addition, the chemical reaction that gives rise ...
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The traditional method of manufacturing SiC compounds is associated with a serious environmental problem, mainly due to the need for large amounts of energy (generally derived from oil) to reach processing temperatures (typically above 2500 ºC). In addition, the chemical reaction that gives rise to the formation of SiC has CO and CO2 as by-products. Therefore, in this work an alternative method to manufacture SiC/Si composites using waste from the wood industry as the main raw material was developed. SiC/Si composites were fabricated by infiltration of molten silicon into carbon preforms at 1500 °C. The carbon preforms were obtained by pyrolysis (in an inert Ar atmosphere) of four types of resin-carbon mixtures. The carbon used in the mixtures was obtained by pyrolysis of sawdust powder.The mechanical and thermomechanical behavior in uniaxial compression was studied at a constant compression rate of 0.05 mm/min at different temperatures (ambient, 1100 °C and 1400 °C). The maximum resistance values found were in the range of 58 and 384 MPa, while the Young's modulus values were between 40 and 120 GPa. The porosity found in the materials was between 1 and 4%. Finally, the fabricated compounds presented a homogeneous microstructure of interconnected silicon carbide in gray contrast and dispersed and unconnected whitish phases of uniformly distributed silicon.
Barbara Lipowska; Bronisław Psiuk; Mirosław Cholewa
Abstract
Cellular SiC/iron alloy composite with a spatial structure of mutually intersecting skeletons created with a porous ceramic preform has not been obtained before, despite promising spectrum of potential uses. We tested the possibility of obtaining such material using a SiC material with an oxynitride ...
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Cellular SiC/iron alloy composite with a spatial structure of mutually intersecting skeletons created with a porous ceramic preform has not been obtained before, despite promising spectrum of potential uses. We tested the possibility of obtaining such material using a SiC material with an oxynitride bonding and grey cast iron. Porous ceramic preforms were made by pouring the gelling ceramic suspension over a foamed polymer base which was next fired. The obtained samples of materials were subjected to macroscopic and microscopic observations as well as investigations into the chemical composition in microareas. It was found that the minimum width of a channel in the preform, which in the case of pressureless infiltration enables molten cast iron penetration, ranges from 0.10 to 0.17 mm. It was also found that the ceramic material applied was characterized by good metal wettability. Were the channels are wide enough for the metal penetration we observed that the ceramics/metal contact area always has a transition zone in which mixing of both components takes place.
Ilan Shalish
Abstract
Growth of epitaxial layers is required for most of today’s devices. Epilayer growth is commonly carried out under conditions less optimal than those of bulk growth. In materials having multiple stable polytypes, such as SiC, it may facilitate concurrent nucleation of undesired polytypes. Using ...
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Growth of epitaxial layers is required for most of today’s devices. Epilayer growth is commonly carried out under conditions less optimal than those of bulk growth. In materials having multiple stable polytypes, such as SiC, it may facilitate concurrent nucleation of undesired polytypes. Using ballistic electron emission spectroscopy, we have repeatedly encountered a spectral feature in chemical vapor deposition (CVD) grown 6H-SiC layers that was absent in spectra of bulk material. This feature is suggested to belong to 4H-SiC inclusions. The presence of a concurrent Schottky barrier in our CVD epilayers coincides with an observation of a lower Fermi level pinning position compared with bulk material. Copyright © VBRI Press.
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