NANOMATERIALS (JOURNAL OF NANOCOMPOSITE MATERIALS RESEARCH)
Year:2013 | Volume:5 | Issue:15|Papers Count:8

In this study, hot corrosion behavior of two-types of plasma sprayed thermal barrier coatings (TBCs), was evaluated: a) usual CSZ (ceria-stabilized zirconia) and b) layer composite coating (CSZ/Nano-Al2O3). Hot corrosion test was carried out on the surface of coatings in sulfate and vanadate molten salts at 1050oC for 40 h. Microstructures and various phases were examined by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. As the results usual CSZ degraded, the formation of monoclinic ZrO2, rod type crystals of CeVO4, YVO4 and semi-cubic crystals of CeO2 as hot corrosion products caused the degradation of mentioned TBC. Dense nano-alumina coating as an outer layer in layer composite coating reduced the infiltration of molten salts into TBC structure and resulted in the further resistance against hot corrosion.

In this study, Al/nano-MgO composites were produced via vortex method (direct incorporation). MgO nanoparticles with 60-80 nm diameter (as reinforcement) and Al-356 (as metal matrix) were used for production of these composites. The molten composites were stirred, and then cast into a metallic mold. The effects of MgO volume percent with 1.5, 2.5 and 5%, and casting temperature (various temperatures, viz. 800, 850 and 950oC) on mechanical properties of composites were investigated. Results show that mechanical properties of samples have increased significantly compare to matrix metal. In this regard, the best compressive strength and hardness results were obtained in the specimens containing 1.5 and 5 vol% nano-MgO produced at 850oC (which are 896 MPa and 73 HB), respectively.

In this survey, the method of chromium extraction from potassium chromate and sedimentation on copper cathode by the method of hydrometallurgy has been considered. This method includes two stages: solvate and electrolysis. In the solvate stage, the effect of the concentration of chromium and the sulfuric acid to potassium chromate ratio was studied and in the electrolysis stage, the effect of density of current, pH, the distance between anode and cathode, the concentration of electrolyte and the temperature has been studied. The optimum conditions of extraction of chromium from electrolyte in the electrolysis stage have been specified so: density of current of 8-10 A/dm2, pH 1.8-2, the distance between anode and cathode 1.5-3.5 cm, concentration of chromium of 5 g/l, the concentration of nanographene powder of 1 g/l in the temperature of 40-50oC has been specified. In this study, characterization of nanocomposites has been done to study their resistive features against any type of scratch or rubbing. In these surveys increase in resistance for chromium-graphene nanocomposite was shown. Also it was concluded that although a copper plate with chromium layer has enough surface solidity, maximum tensional resistance, rendition resistance and elongation percentage, but resistance against stroke for this plane is low and the copper plate with chromium-graphene plate exhibits better pulse resistance characteristics.

In this study, the effect of reinforcement nanoparticles on mechanical properties, and corrosion resistance of Al/SiC nanocomposite have been studied. Al/SiC Nano composite powder with different reinforcement weight percents prepared by ball milling. Then being cold and finally the pressed samples had been hot extruded. Microstructure of composites showed the uniform distribution of reinforcement phase and a small amount of agglomeration in the microstructure was observed. The micro-hardness examinations and tensile test revealed that the mechanical properties improvement by increasing reinforcement particles in Al matrix, but the results of electrochemical tests showed that with the increase of reinforcement phase the corrosion resistance has been decreased.

In this paper, ZnO/Cu2O nanostructures were synthesized via molten salt and hydrothermal method. At the first step, the ZnO hierarchical nanostructures were successfully prepared by molten salt method at 200oC without any calcination and post treatment. The hierarchical star-like structures were used as core due to higher light absorption. Secondly, Cu2O nanoparticles were formed on the arms surfaces of ZnO star-like particles via facile hydrothermal method. X-ray diffraction, UV-Vis spectrum analyses were used to characterize the phases and optical behavior of core-shell structures. Microstructures of core-shell particles were also analyzed by scanning electron microscopy. Based on the result, the higher light absorption of core-shell structure made them as a good candidate to apply in photoelectrochemical cells.

In this research, based on graphene oxide nanocomposites were discussed. For this purpose, the well-known method of Hummers-Offer man of graphene oxide to graphene oxide by strong acid to convert and by using FT-IR, XRD and SEM, and its structure was confirmed as a good substrate for different reactions. After studies of the monomer in the Iranian market relatively easily accessible and were prepared, namely methyl methacrylate with different percentages were used for the preparation of polymer nanocomposites based on graphene oxide. Results improve heat resistance properties and the methyl methacrylate, the effect of increasing the weight percentage of graphene shows. Carboxyl functional groups in graphene oxide, which causes structural readily react with chemical monomers, can be also used as case study in the FT-IR was detected. This was also observed in SEM image the addition of roughness of the polymer surface has been reduced graphene oxide can cause the mechanical properties of polymers can improved. Thus, the surface properties of the nanocomposites investigated and physical/mechanical properties such as electrical conductivity, thermal behavior, it is expected that the improved properties of nanocomposites and in subsequent reactions as suitable for other chemical reactions used or as well as a drug (drug carriers), or its application in the removal of toxic compounds in environmental water should be studied further.

In this research, effect of adding iron oxide nanoparticles on efficiency of algal biomass produced for chromium elimination. Initially to this end dried and crushed algal biomass, in continuation mixture of algal biomass with iron oxide nanoparticles absorbents used for chromium elimination from water. The water that used in these experiments had four different concentrations of chromium, and results showed that the best absorber for water refinement is the mixture of algal biomass with iron oxide nanoparticles absorbents. Also 10 ppm concentration is best concentration on other hand in all experiments that used of iron oxide nanoparticles Cr6+ was conversion to Cr3+.

In this study, Fe3O4 nanoparticles were synthesized via chemical co-precipitation method and effect of lauric acid concentration on particle size and magnetic properties of these nanoparticles were studied. To obtain Fe3O4 nanoparticles, ferric and ferrous chlorides were precipitated by adjusting the pH by ammonia at presence different concentrations of lauric acid dynamic laser diffraction (DLD) method was used for particle size distribution. Structure and morphology of particles were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Magnetic particles were measured by using alternative gradient force measurement (AGFM). XRD results showed that e-Fe2O3 can be present beside Fe3O4 phase as minor phase which is related to surfactant concentration and disappears in optimum concentration of surfactant examined AGFM revealed that increasing concentrations of lauric acid, saturation magnetization is reduced. Moreover it was revealed that crystallite size various from 10 to 22 nm.