Journal of Nano Research Vol. 45

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作者: S. Nallusamy
摘要: Composite materials are the leading emerging materials over the past twenty years since its introduction. Among the natural composites, carbon black-halloysite nanotubes hybrid composite is one of the recent emerging sector in the composite field, because of its high strength with less density as compared to the metal matrix composite. In this research carbon black-halloysite nanotubes hybrid composites based on synthetic rubber copolymer of acrylonitrile and butadiene were prepared and tested. The carbon black loading was kept fixed at sixty per hour and halloysite nanotube loading was varied from zero to ten parts per hundred rubbers per hour. The effect of carbon black-halloysite nanotube hybrid fillers on the curing behaviour, mechanical properties and morphology of the high nitrile rubber nanocomposites were investigated. The cure characteristics showed that the scorch time and cure time increased with the halloysite nanotube loading. The maximum torque exhibited an increasing trend from zero to six per hour. The tensile properties which exhibited an increasing trend until an optimum loading of six per hour were mainly influenced by the high nitrile rubber-carbon black-halloysite nanotube interaction and the intercalation of rubber and carbon black into the tubules. X-ray diffraction test and scanning electron microscope studies were supported to the results obtained.
作者: V. Karoutsos, Odyseas Venetsanos, Dimitris Geralis, Panagiotis Poulopoulos, C. Politis
摘要: Three different Fe-C alloys were prepared in vacuum using the arc melting method: hypereutectoid (1.4% C), eutectoid (0.76% C) and hypoeutectoid (0.4% C). Unlike commercial steels, which they always contain Mn and other impurities, our samples were prepared by using high quality powders (99.999 wt.%). The samples were heat-treated and then observed with optical and scanning electronic microscopy (Zeiss EVO MA10). Selected samples were tested by microidentation (microhardness test). After isothermal transformation at 350 °C fine bainite nanostructures were observed in the hypoeutectoid sample, the mean size of which was found to be 50 nm. With the eutectoid sample, following different heat treatment procedures different micro-and nanostructures were measured: pearlite lamellar spacing, spheroidized cementite particles, and martensite needles, whose mean size is 145 nm, 290 nm and 200 nm respectively. The nanostructure of hypereutectoid sample after isothermal transformation at 650 °C, reveals the eutectoid and proeutectoid cementite lamellas with a mean spacing of 390 nm. X-ray diffraction pattern of eutectoid sample indicated the existence of cementite (Fe3C) content which is also confirmed by carbon mapping of pearlite colonies performed with Energy Dispersive X-ray Spectroscopy. The Vickers hardness of the samples compares well to the one of corresponding commercial steels.