مجله مواد و فناوری های پیشرفته
سال نهم شماره 2 (تابستان 1399)

In this study, PMMA-SiO2 transparent superhydrophilic nanocomposite film was applied by immersion method on glass substrate. Then the samples were annealed at 100 and 500 °C. Field emission scanning electron microscope (FE-SEM), energy disspersive spectroscopy (EDS), atomic force microscope (AFM), UV-VIS spectrometer, and water contact angle analyserwere used to studythe morphology, elements percentage, surface roughness, and optical and hydrophilic properties of nanocomposites. The coating transmission spectra showed that the transparency of the glass substrate did not decrease with PMMA-SiO2 nanocomposite film and remained unchanged. In addition, the wettability results for the annealed samples at 500 °C showed a decrease in the contact angle of the substrate from about 34.1° to about 0°.

The biosorbent nanochitosan was synthesized by the ionic gelation and modified with lanthanum to improve efficiency and performance. The features of synthesized adsorbents were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray diffraction (EDX) and nitrogen adsorption–desorption isotherms and after confirming the nanostructure adsorbent, used as a suitable adsorbent for phosphate removal. In order to correct the results of the adsorption process, Langmuir and Freundlich adsorption models were used. The results showed that the adsorption of phosphate on lanthanum-modified nanocitosan adsorbent follows the Langmuir isotherm and the maximum adsorption capacity is 144.92 mg/g. The equilibrium time of adsorption process was also studied on lanthanum modified nanocitosan and experimental data showed that the time required to reach equilibrium was 30 min. The kinetic studies of the adsorption process will also be performed on lanthanum modified nanocitosan and the kinetic information obtained will be evaluated by pseudo-first, -second order and intra-particle diffusion kinetic models. Investigation of three kinetic models showed that the adsorption process with a 0.9967 correlation coefficient is in good agreement with pseudo-first kinetic model.

The study aimed to investigate the performance and evaluate the effect of incorporation of Cu and Mg on the structural, biological, and bactericidal properties of the sol-gel derived 58S bioactive glass containing Mg and Cu. The structural and morphological evaluations of the synthesized glasses were performed by the mean of X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) analysis. The effect of Cu and Mg content in the composition on the quality and quantity of in vitro bioactivity was examined by performing 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and alkaline phosphate (ALP) analysis. The antibacterial performance of Cu and Mg incorporated bioactive glasses were evaluated against MRSA bacteria. The results confirmed the formation of a hydroxyapatite layer on the glass surface. Adding copper and magnesium to the 58S bioactive glass composition increased cell activity and proliferation and improved antibacterial performance. The results suggest that BG-5/5 (including 5 mol % of both CuO and MgO) as the bioactive glass with the optimal amount of magnesium and copper in its composition.

In the present study, Graphene oxide (GO) was deposited using inexpensive and environmentally-compatible methods on the nickel oxide foam. Then, GO thin films have been reduced by Cyclic Voltammetry (CV), Chronoamperometry and Chronopotentiometry modes of electrodeposition. The effects of different modes on structural, surface morphological and supercapacitive properties of ERGO thin films have been investigated by X-ray diffraction (XRD), Scanning electron microscope (SEM), Raman spectroscopy, Cyclic Voltammetry, and Galvanostatic charge and discharge (GCD). Formation of ERGO by all three modes is confirmed by X-ray diffraction (XRD) patterns. A Significant change in the surface morphologies of the ERGO thin film due to different modes has been observed. The supercapacitive properties of ERGO thin films have been studied in 1 M KOH electrolyte. The maximum supercapacitance obtained for potentiodynamic, potentiostatic, and galvanostatic modes is 1380, 1259, and 1995 F/g, respectively which is completely in agreement with the special level and impedance results. The results showed that the constant current method is the best way for the electrochemical reducing of graphene oxide. In this way, most functional groups have been reduced. In addition, a high density of the defects and wrinkling of the sheets is observed. Consequently, the method can replace chemical methods for the reducing of graphene oxide and eliminate the major weakness of chemical methods that use toxic substances.

Nickel-based superalloys, due to their unique properties such as tensile strength, creep strength and fatigue strength as well as high temperature corrosion and oxidation resistance, have a special place in the oil and gas industry, space vehicles, submarines, reactors, military electric motors, chemical ships and heat exchanger tubes. Among the nickel base alloys, Inconel X-750, a hardened sediment alloy, was investigated under different heat treatment cycles. First, all samples were dissolved in the same size for 2 hours at constant temperature 1155 ± 5 °C. Then they were cooled in the furnace at low cooling rates and aged at constant temperature for 24 hours at four different temperatures of 600, 705, 760 and 845 °C. In the literature, studies of microstructures by light and electron microscopy showed that both environmental and cooling conditions after solution and aging treatment affect morphology, volume fraction and particle size of primary and secondary gamma prime. As the temperature of the aging process increases, the morphology of the γ' will shift from a spherical to a cubic state and become larger while its volume fraction would decrease. The aging temperature also plays an important role in the formation of the precipitate free zone (PFZ) around the grain boundary which means that with the increase of the aging temperature, the thickness of PFZ would be increased.

In current study kaolin-Zein composite was prepared and its performance was investigated via methylene blue adsorption. For preparation of mentioned adsorbent, kaolin were coated using Zein as natural polymer via solution blending method. The kaolin-Zein composite was characterized by Fourier transform infrared (FTIR) spectroscopy, Zeta potential and particle size analysis. The obtained results confirmed kaolin coating with Zein. The effect of pH on adsorption capacity showed that the adsorption capacity increased when pH increased. Adsorption yield versus time was determined at different adsorbent dosage. The results demonstrated that the adsorption process reached equilibrium at the optimal modified adsorbent dosage of 0.6 g/l and pH of 9 after 60 min. The adsorption yield of kaolin composite was improved about 30 % when compared with that one of pure kaolin at the same operating condition (temperature, pH, adsorbent dosage and contact time). Adsorption capacity values were appropriately fitted to Freundlich, Langmuir isotherms and pseudo second order equation as governing kinetic model. Moreover, maximum adsorption capacity of 135 mg of methylene blue per g of kaolin-Zein was obtained.

Cordierite (2MgO,2Al2O3,5SiO2) is one of the compounds in the MgO-Al2O3-SiO2 triple diagram which they have properties such as low dielectric constant and loss tangent, very low thermal expansion coefficient, refractory and suitable chemical and mechanical stability. In this study, α-cordierite was synthesized using the solid state reaction method of oxide powders (aluminum oxide, magnesium oxide and silicon oxide) and MK silicone resin. To investigate the synthesized samples, X-ray diffraction test was performed and showed that α-cordierite is formed at the temperature of 1400 °C. By performing the micro hardness test, it was observed that the hardness of the synthesized α-cordierite is equal to 12.35 GPa. Three-point bending test was performed to evaluate the flexural strength and the flexural strength was 62 ± 3.6 MPa. Also, the dielectric constant of 3.18-3.22 (in the frequency range of 8-12 GHz) and the loss tangent of 0.001-0.005 were obtained for the synthesized α-cordierite.

In this research, PbTiO3 (PTO) thin films with 150 nm thickness were grown on (001) Nb-doped SrTiO3 substrate. High-resolution X-ray diffraction (HR-XRD) studies showed that the PTO films are epitaxial with [001] orientation. The ф-scan of the film and substrate around {102} revealed a fourfold symmetry for both demonstrating [001] perfect orientation of the films. XRD reciprocal space map around (103) of the film and substrate revealed that film is fully strained with a compressive strain. The lattice constants calculated from the horizontal and vertical peak positions are; a = 0.403 nm and c = 0.407 nm. This compressive strain was developed due to the coherent interface formation in the film and substrate interface and the lattice parameter mismatch of the film with respect to the substrate. Topography studies by atomic force microscopy (AFM) showed that films are highly uniform with densely packed elongated grains developed along the [100] and [010] orientations. Ferroelectric domain configuration of the film was investigated by a piezoelectric force microscope (PFM). Two types of 180 and 90 degrees ferroelectric domains were observed. The epitaxial compressive strain is responsible for the formation of 90 degree domains. The developed strain via the lattice mismatch between the PTO layer and the substrate enforces electrical dipoles to rotate away from the normal direction to compensate the elastic energy of the film.