Preparation And Application Of Nanostructured Silicon Carbide

Nanomaterials are the basis of nanoscience and nanotechnology, and they play more and more important role in many fields, such as information storage, electrooptical devices, catalysis and sensors etc., owing to their novel physical, chemical, and biological properties. As a result, huge effort has been devoted to the preparation and application of nanomaterials.Silicon carbide (SiC) is a kind of excellent semiconductor materials, which has many superior properties, such as wide band gap, high thermal stability, high mechanical strength and strong resistance to oxidation and chemical corrosion. These properties allowed SiC to be operated at high temperature, high power and in harsh environments, made them have broad application. That is also a promising candidate to be used as reinforcement in ceramic-, metal-, and polymer- matrix composites.Up to now, the research on SiC has been focused on two aspects:first one is the method to prepare various SiC nanomaterials, include shape memory synthesis, carbon nanotube confine reaction, chemical vapor deposition, arc discharge, sol-gel and carbothermal reduction, etc; second, research its simple application based on excellent properties. In the present work, low-dimensional SiC nanomaterials with different morphologies were prepared by sol-gel and carbothermal reduction method. In the sol-gel process, different additives were employed to control the structure and morphology of SiC nanomaterials. Afterwards, we investigated their structures and characterizated by IR, BET, XRD, TEM, SEM and so on. SiC with different morphologies as a reinforcement added into epoxy resins can increase the mechanical properties of SiC/epoxy composite materials; In the alcohol oxidation test, SiC as the catalyst carrier has a better catalytic effect in harsh environments. Achieved results are summarized as follows:(1) Nano-SiC particles and wires with different morphologies were made by the method of Sol-gel and carbothermal reduction. The factors, such as time and temperature of the reduction, metal catalysts, Acid concentration and so on were investigated during the experiment. And the results showed that:different surfactant can change the morphology and nano-diameter of SiC; Then, acidity led to the monomer, such as Si-OH, RO-Si from the hydrolysis of TEOS. Since metal catalsyst and silicon can form alloys in high temperature, which made the different saturated vapor pressure of silicon alloys. Meanwhile, that also led to the morphology change of SiC nanowires.(2) Using the strong mechanical properties of SiC, add SiC into the epoxy resin to increase mechanical performance of the composites. The experiment investigated the influence of the morphology, content of SiC and coupling agent. The result showed that, SiC/epoxy resin composite materials appeared the best properties when SiC contented for 0.1%～0.5%, coupling agent 0.15%, curing temperature is 130℃and time is 4h.(3) Since SiC has chemical stability and corrosiveness resistance, we first use amino to modify the surface of SiC, then load Pd to prepare catalyst Pd/SiC-NH2, and investigat the catalytic activity of Pd/SiC-NH2 in the alcohol oxidation reaction. Compared with the normal vector of silicon we found that SiC had a higher alkali resistance and better persistence in the alcohol oxidation reaction. And it also had a good catalytic activity; conversion rate and production selectivity.