Materials Science Forum Vol. 1039

Abstract: The nanoparticles synthesized by plants and micro-organisms are environmentally safe and do not leave residues or long-term toxic effects in ecosystems or accumulate in the environment and transfer through the food chain. Therefore, the aim of the research is to synthesize silver nanoparticles from the leaves of the oleander plant, where they are environmentally friendly when used for various purposes such as controlling agricultural pests. The results showed that the leaves of this plant have the ability to synthesize silver nanoparticles and this is confirmed by the tests of color change of the plant extract the reaction solution, the color of the solution changed from colorless to pink. Physical diagnostic tests such as absorption using a UV-Visible spectrophotometer at a wavelength of 340 nm, transmission electron microscope (TEM) and X-ray diffraction (XRD) technique have confirmed the formation of AgNPs in the leaves of a plant oleander. Keywords: silver nanoparticles, synthesis, environmentally friendly, physical diagnosis

Abstract: Abstrac. In the present work, gold nanoparticle (Au NPs) was synthesis by pulsed laser ablation (PLA) by using Q-switched, (Nd: YAG) (E=80mJ) (λ=532,1064nm) and Number of pulses (500)pulse of the gold metal target in deionized water. The optical properties were studied with a UV-vis spectrophotometer which tests the absorbance spectra and comparison of the generated nanoparticles solution. atomic force microscope (AFM) results show that the grain size increase by decreasing wavelength. The optical limiter of the resulting colloidal solution was studied.

Abstract: Multi-walled carbon nanotubes (MWCNTs) probably hold with each other and agglomerated due to van der Waals force. Functionalized process was used to reduce its ability to agglomerate and to increase dispersion in solution. The present work is focused on the microwave irradiation in order to achieve rapid functionalization of MWCNTs compared with other known techniques. The power of microwave radiation was selected by investigating the structural integrity of the samples by X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FE-SEM), while BET surface area measurement was used to measure the MWCNT surface area before and after treatment. The dispersion test in the solution was performed to determine the separation capability of untreated MWCNTs and f-MWCNTs.

Abstract: Europium doped Titanium dioxide (TiO₂) nanoparticles were prepared by Sol-Gel technique under varying condition to investigate the effects of Eu3 + doping on the optical properties of Titanium dioxide nanoparticles. The transmittance spectrum is clearly visible at wavelengths 394nm and 416nm, and is a result of electronic transitions of energy level of the Eu3 + ions. . The obtained composites for different doping concentration were analyzed by using Energy Dispersive X-ray Spectroscopy (EDS). The linear and nonlinear optical properties of the composite were studied using the Z-scan technique, and there was an increase in the nonlinear refractive index with an increase in the concentration of the Eu⁺³, where it reached its highest value, which is 3.01×10^-10 at doping 2.3 while the linear absorption coefficient was an inverse proportion, where the highest value was at Pure titanium and it is 1.0296951×10-⁵ (cm/mw).

Abstract: This paper displays the fabrication of a thermoelectric (TE) generation module using n-ZnSb and p-Zn_0.25Cd_0.75Sb bulk TE materials. TE properties of the Zn_1-xCd_xSb bulks with x= 0, 0.5 and 0.75, in terms of the electrical conductivity () and Seebeck coefficient (S) were measured in the range of 300-500K. The higher power factor (S²σ) values for n-ZnSb and p-Zn_0.25Cd_0.75Sb bulks were obtained about 2.410^-4mW/mK² at 303K and 1.1810^-5 mW/mK² at 468K, respectively. By variation of the thermal conditions, the maximum output power (P_max) with two p-n couples generator module was 1.3810^-5 mW at hot side temperature of 355K and temperature difference () of 40K. The internal (R_in = 0.17 m) and contact resistances (R_c = 0.67 m) between legs and electrodes were discussed below.

Abstract: The role of formic acid as Secondary Dopant for Poly (O-toluidine) Intrinsically Doped with Camphor Sulfonic-Acid (POT-CSA) nanoparticles were prepared by chemical polymerization had been studied. Spin coating and casting method have been used to deposit good adhesion and uniform thin films of (POT-CSA) on a glass substrates at room temperature. the properties of (POT-CSA) nanoparticles which examined by FTIR, SEM, AFM, XRD, I-V characteristics and UV-VIS. FTIR studies show the several bending and stretching modes of POT. XRD examination demonstrated that NPS. has a semi-crystalline pattern . The synthesized film well covered by the nanoparticles over the entire substrate surface, exhibits uniform, porous, and spherical granular surface morphology, A narrow size distribution is observed and the average size of particles about 80 nm. The band gap (Eg) has been determined which is equal to 3.1 ev. The room temperature conductivity of POT-CSA was 3 * 10-1 S.cm-1,which increases with increasing temperature. Electrical conductivity enhances up to three order after the secondary doping process. Keywords: POT-Chemical polymerization-Conducting polymer-SEM-AFM

Abstract: Recently, the researchers gave a great interest in the superconducting topic, as the preparation method is importance to reach a high critical temperature. In this study, the Bi₂Sr₂Ca₂Cu₃O₁₀ (Bi-2223) compound prepared by thermal treatment method at different sintering temperatures such as (600, 700, 850) °C at (7) PH for (20 hrs). The phase formation was observed by X-ray diffraction, as well as information about the crystal structure, as the peaks were almost identical to the international standard document. the peaks are well indexed by tetragonal phase of Bi-2223. The results of the electrical resistance test showed that there is a difference in the critical temperature depending on the difference of the sintering temperatures The best result was at a temperature of 850 ° C. The sizes of the nanoparticles ranged from (22 - 123) nm, this is what the TEM measurements showed. It has been shown to be a successful method for preparing superconducting nanoparticles as (Bi-2223) compound

Abstract: The aim of this study is to analyze the phase change material cooling performance integrated into heat sink experimentally. a paraffin wax as phase change material is used in this experiment and it placed under the heat sink with thickness 30mm , various power input at 11W,13W and 15W used in this experiment to generate heat at different levels also several fan speed at 15m/s,2.5m/s and 3.4m/s. the surface temperature of the heat sink is monitored over the time to evaluate the phase change material thermal performance . From the results ,temperature drop and the time lag in case of without PCM compared to with PCM shows the effect of cooling of adding PCM under low and high speeds of heat removal. It found that inclusion of PCM into heat sink with forced convection shows high temperatures drop up to 18 °C.

Abstract: Heat resistant coatings are considered for the external surface Low-Pressure Steam Turbines (LPST). 410 stainless steel covered with nano heat resistant coatings consists of a heat resistant connecting layer enhanced by nanoparticles. A commercial paint was modified by using 20%wt of (titanium dioxide (TiO₂) - aluminum oxide (Al₂O₃)) with different concentrations range (25,50,75wt% of TiO₂) layers. These nano-coatings paints were airbrushed onto the surface of specimens of steam turbine blades. The test rig and experimental apparatus have been fabricated and collected to accomplish the thermal tests. The samples were subjected to heat resistance and a temperature test approximately similar to the steam turbine's operation condition temperature. The test results are used to choose the nano-coating layer with a concentration that ensures a composition's highest protective properties. The test sample with concentration (paint-(75% Al₂O₃+25% TiO₂)) showed the highest thermal properties compares with the other cases.

Abstract: Powder technology has a great impact on the industry and the need for the labor market since this technology has been used to manufacture copper-based composition models with a fixed rate of 5% of (SiC) with nanostructuring of (0,5,10,15,20) %. Regarding nanoscale zirconia (ZrO₂), the mineral and ceramic powders were grinded with a grinding time of two hours for the purpose of homogeneity, then the powders were pressed at a pressure of 5 tons and a time of one minute only. Later, the properties were studied and the prepared samples were sintered at 900 °C for two hours.. The physical properties were represented by density and porosity, mechanical properties by compressive strength (samples failed) and wear and structural properties by SEM and EDS. The results showed that the true density and real porosity decreased with the increase in the size of the support ratios, while we noticed an increase in compressive strength with the increase of the added nanoscale ratios. As for the wear, its value decreased to reach the lowest value after sintering and at the ratio of 15% zirconia. Furthermore. the results of the scanning electron microscope showed that the ratio of 15% zirconia is the best percentage in terms of improving physical and mechanical properties. Keywords: nanozirconia, compressive strength, Thermal sintering, porosity.