SiC nano particles with mono dispersed distribution were synthesized by using of silicon alkoxides and phenolic resin as starting materials. After synthesis of sample, characterizations of the obtained powder were investigated via Fourier Transform Infrared Spectroscopy (FTIR) with 400-4000 cm-1, X-ray Diffractometry (XRD), Laser Particle Size Analyzing (LPSA), Si29 NMR analysis, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). FTIR and Si29 NMR results of the gel powder indicated that Si-O-C bonds were formed due to hydrolysis and condensation reactions. FTIR results showed a very strong peak for heat treated powder at 1500oC after carbon removal which is corresponded to Si-C bond. Obtained pattern from X-ray diffractometry showed that the final products contain b-SiC phase with poly crystalline planes and little amounts of residual carbon. PSA results showed that the average particles size were 50.6 nm with monosized distribution. Also microstructural studies showed that the SiC nano powders have semi spherical morphology with mean particles size of 30-50 nm and also there are some agglomerates with irregular shape.

The aim of this research is to determine the proper concentration of Titanium Tetra IsoPropoxide (TTIP) and select the right temperature and time of calcinations for the synthesis of B4C-nano TiB2 composite Nano powder by the chemical precipitation method. For this purpose, first, solutions with TTIP molar concentrations of 0.1, 0.05 and 0.03 were prepared and the optimal molar concentration of TTIP was determined to be 0.05. Then, a diluted solution of distilled water and TTIP was mixed with Isopropanol Alcohol containing B4C micro powder. In this mixture, Titanium Hydroxide nanoparticles were initially synthesized and then, to convert the Ti (OH) 4 to TiB2, the above mixture were calcined in a furnace, under Argon atmosphere. The calcination process was carried out at temperatures of 750, 1000 and 1250 ºC. It was observed that the most suitable temperature for the formation of the TiB2 phase is 1250 ºC and that the lower temperatures only lead to the formation of the TiO2 phase. It was also observed that, at the calcination temperature of 1250 ºC, the most appropriate time duration for the conversion of Ti (OH) 4 nanoparticles to TiB2 nanoparticles is 30 minutes, during which B4C-nano TiB2 composite Nano powders form, with most of the TiB2 particle sizes being in the range of 30-60 nm.

In this study metal oxide nano powder namely NiO nanopowder was prepared .The produced metal oxide was characterized and used as potential adsorbent for the removal of Pb and Zn from aqueous solution. The rate of uptake of the Pb and Zn are rapid in the beginning and the time required for equilibrium adsorption is 120 min .The time of equilibrium as well as time required to achieve a definite fraction of equilibrium adsorption is independent of initial concentration. The results showed that the removal of Pb increased significantly as the pH increased from 2.0 to 6.0 and approach a plateau at pH range of 6.0-9.0., while the removal of Zn increased significantly as the pH increased from 2.0 to 9.0. The adsorption of pb onto NiO follows the Langmiur isotherm, while the adsorption of Zn onto NiO follows the Freundlish isotherm. The pseudo second order kinetic model provided good correlation for the adsorption of Pb onto NiO nanopowder while the pseudo first order kinetic model provided good correlation for the adsorption of Zn onto NiO nanopowder.

MgAl2O4 (MA) nano powder was synthesized via molten salt technique, by heating stochiometric composition of MgO and nano boehmite. The reactant and potassium chloride, as the reaction media, were fired at 800-1000 oC at different dwell times (0.5-5 h) in the ambient atmosphere. After washing and filtration, the spinel nano powder was characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) techniques. It was demonstrated that the formation temperature decreased to 850 oC. The nano spinel particles revealed an average size of 30 nm with a narrow size distribution. The mechanism of MgAl2O4 formation was found to be a template type where the morphology and size of product were similar to those of alumina formed from boehmite decomposition. Prolonging the reaction time from 0.5 to 3 h, the reaction was further completed and crystallinity was improved. However, the increase of temperature was more effective in this regard.

According to the unique properties and many applications of nano gold powder, it was prepared from an acid leaching tail solution. The low value residual gold ions existed in acid leaching tail solution in Mouteh gold mine in Iran with fellow heavy metals as pollutants (Fe2+, Cu2+, and Zn2+). Preparation of nano gold particles is achieved by two steps: First, by addition of ammonia as separation step and second by using the suitable reagents for precipitation and extraction step. Control conditions include pH, residence time, temperature, agitation, molar ratio of reducing agents to reagents. The optimum results show that nano gold powder was prepared by temperature of 250 °C, urea to gold molar ratio of 3: 1, and reduction time of 20 min. Also, heat treatment improves dispersion of nano sized gold particles. The properties of gold nano powders were evaluated by SEM, A.A and UV-Vis spectroscopy methods and the size of particles were about 80 to 90 nm.

Due to significant environmental advantages, biocomposites have recently received increasing attention. In the present research, strength of hat-shaped coir fiber biocomposites tubes reinforced with nano powder was evaluated experimentally under 3-point bending tests. The tubes were manufactured using hand lay-up technique and based on Taguchi design of experiment. The effects of different parameters including fiber loading, type of nano powder and its weight percentage and also weight percentage of NaOH in alkali treatment were analyzed. Optimization was also performed using Taguchi L8 orthogonal array. Moreover, analysis of variance (ANOVA) was conducted to determine the significance of the parameters. In this study, finite element model was also created in ABAQUS software to compare with the results obtained from the experiments to achieve validated finite element model. There was a good agreement between the results from experiments and those obtained in numerical simulations.

In this study, hydroxyapatite (HA) Nano composite powder with 0, 4 and 8 wt. % silver were synthesized via sol-gel method. Phase formation, thermal stability, microstructure and particle size distribution were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), dynamic light scattering (DLS) and EDS mapping. Results showed presence of silver as a reinforcement phase caused a decrease in thermal stability of HA phase and decomposition of HA to b-TCP phase was increased. The microstructure characterization revealed that silver particles until 4 wt. % uniformly distributed in HA matrix and the particles were in nano-sized.

In the present study, ZrB2 nano powders were synthesized using sol-gel method. Zirconium alkoxide was used as the source of zirconium and boric acid as the source of boron. The size of precursor nanoparticle was controlled using the pH parameter inside the sol, and the formation of primary nuclei of ZrB2 phase and their crystallized amount were investigated using the temperature parameter. To evaluate the mechanism of product formation during the sol-gel process, TEM, SEM, DTA / TG, RAMAN, XRD, FTIR, and DLS methods were used. DLS analysis showed that the size of precursor particle inside the sol at pH less than 5 was below 10 nm. Measurements of viscosity and zeta potential inside the sol showed that in the acidic range, the particle stability decreases with increasing pH. Mixing of precursor particles at molecular level inside the sol was one of the important reasons in reducing the synthesis temperature of ZrB2 particles. FTIR analysis on chemical bonds showed that Zr-O-B bond was formed inside the gel powder. DTA analysis showed that the primary nuclei of ZrB2 particles were formed at a temperature of about 1400 °, C. XRD observations proved that the primary nuclei of the ZrB2 phase crystallized and grew at a temperature of about 1500°, C. Surface research revealed that the specific surface area of the synthesized ZrB2 particles is equivalent to 115 m 2 /g, and also the surfaces of these particles are porous, and the size of these porosities is in meso range. SEM analysis showed that the particle size of ZrB2 having homogeneous morphology is about 50 nm. TEM microstructural analysis revealed that ZrB2 particles were formed uniformly and orderly in very fine dimensions.

Due to the limited uranium reserves and advantages of thorium fuels over uranium fuels, the development of the thorium fuel cycle in various countries including Iran, has been considered significantly. One type of thorium fuels used in nuclear reactors is a mixture of uranium dioxide and thorium. The type of powder synthesis method is a key point in improving the efficiency of this fuel in the reactor. The main objective of the present study was to achieve mixed nanoparticles of 30-70% (Th-U)O2. The effect of four parameters including concentration, time, initial percentage of uranium-thorium nitrate in solution, and temperature was studied using Taguchi's experimental design. The synthesized nanoparticles were characterized by XRD, BET, EDS, and SEM analyses. The results showed that at the best conditions, the nanoparticles were synthesized with a weight percentage of 32. 28 and 67. 72%, a particle size of 13. 25 nm, high purity, and high surface area. Also, the results showed that the supercritical hydrothermal method has performed well for mixed nanoparticles of 30-70% (Th-U)O2 production.