Journal of Advanced Processes in Materials Engineering
Year:2018 | Volume:12 | Issue:1 (44) |Papers Count:11

Gas sensors are now widely used for routine monitoring of the quality of atmospheres. A sensitive PEDOT: PSS/Fe(salen) thin film based toxic gas sensor deposited on glass pieces with interdigitated Au electrodes was developed by the spin coating method. The obtained composite was well characterized by different techniques such as UV– vis spectroscopy and FTIR. Also, the surface topography of thin film composite was investigated using AFM. The Fe(salen)-doped PEDOT: PSS on interdigitated electrode was experienced an immediate decrease in resistance when exposed to carbon monoxide gas under normal dry room temperature conditions (%RH=20). The results showed that the response of desired sensor was not unidirectional, and reverses to the original resistance level when CO was removed from the test chamber (RD< 2%). The highest response factor and lowest response time (t90) obtained were equal to 40± 0. 77% and 38s, respectively. Ultimately, the optimum level of doping (0. 02 wt. % of Fe(salen)) was determined.

sample obtained from an alumina-zirconia composite following mechanical milling. To this end, alumina and zirconia powders were used as the raw materials and niobium oxide powder was used as additive. All of the alumina-zirconia composites contained an invariant zirconia content equal to 10 weight percent, and 1 weight percent of niobium oxide was added to composite samples. Composite powders were subjected to axial pressure in tablet casts. Afterwards, samples were exposed to sintering for two hours in a thermal furnace at a temperature of 1300 to 1500. X-ray diffraction was used to identify phases, and microstructures were examined through the SEM (scanning electron microscope) method. Examination and experiment results indicated that niobium oxide considerably influenced sintering density, and increased density up to 3. 75 g/cm3. On the other hand, the size of background particles increased to 2. 19 microns after sintering and the tetragonal phases decreased. In this research, the effect of this oxide on the sintering mechanism of the alumina-zirconia composite and stability of the zirconia tetragonal phase were discussed and analyzed.

In this study, the impact of )1-Buthyl-3-methyl imidazoloum hexa fluorophosphatesas( a new inhibitor on the corrosion of stainless steel 316L (SS) in HCl solution was investigated by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Also, the absorption of inhibitor onto the SS surface followed the Langmuir absorption model with the free energy of absorption Δ G0adsof-8. 57 kJ mol-1. In addition, using density function theory (DFT) and atoms-in-molecule (AIM) theories, introduced by Richard Bader, which is a generalization of quantum theory to proper nano-size and molecular systems, the electronic organic-structure and local charge/energy transfer in the imidazole molecular system (as a organic-corrosion inhibitor element) are studied. In the same vein, the atomic electronic properties (such as electron density and its Laplacian), and the HOMO– LUMO gap (HLG) of this organic-molecular system are calculated. The results of the investigation show that proposed compound, as a commodious/economical-green inhibitor, has excellent inhibiting properties for SS corrosion in acidic solution. Furthermore, quantum mechanical results show that nitrogen atoms play domain role in intra-molecular charge and energy transfer (and thus electrochemical mechanism) in this inhibitor.

This study examines the influence of NiCrAlY powder with and without Al2O3 Reinforcement doses of 5, 10 and 20% by weight, produced by plasma spraying method have been investigated. In order to prepare a composite powder, shaft ball mill blender for an hour for each powder were used. The NiCrAlY powder and powder composite NiCrAlY / Al2O3 with values of 5%, 10%, 20% Al2O3 were coated on Inconel 718 substrates by plasma thermal spraying. In order to evaluate the microstructure, morphological and thermal stability evolutions of the powders and coatings were investigated using X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy and optical microscopy. Vickers micro and macro hardness test was used to evaluate the hardness. . The pin-on-disk test with 5 N was used to cold resistance assessment of coatings. Findings showed that the composite coatings NiCrAlY/Al2O3 because of the size and morphology of different ingredients, has a higher porosity, but in terms of mechanical properties due to reinforced phase, improvements in composite coatings were observed. Evaluate the wear behavior of Al2O3 10% coatings showed that 37. 7× 10-6(mm3/Nm)abrasion resistance better than other coatings, especially coatings from powders without reinforcement 114. 6× 10-6 (mm3/Nm) abrasion resistance had.

In this research, the process of TLP joint for super alloy FSX-414 by using the interface layer of MBF-100 as ribbon or powder have been studied. For this purpose, two samples of cobalt base alloy super clubs FSX-414 with dimensions of 10 mm for connecting sample with MBF ribbon & the other with the same dimensions with U&V shape track for connecting with powder have been done. In the following, both samples were subjected to a heat treatment cycle at temperature of 1175 degree of centigrade for 30 minutes’ microstructure of TLP connection area was investigated by using light microscope, scanning electronical microscope & EDS analysis, EDS map analysis & micro hardness. In microscopic pictures related to TLP bonding with ribbon & sample of powder of fuzzy areas, including the area under fuzzing & influenced area were specified completely. The result of EDS analysis & EDS map analysis & micro hardness of penetration capability& better connecting of ribbon rather than powder has been valided.

In the present study, mesoporous magnesium silicate (m-MS) was synthesized via non-ionic surfactant-assisted sol-gel method. The m-MS was produced into an acidic medium and calcined at 550 º C temperature to remove the organic template (P123). The aim of this study was to evaluate the ability and application of drug loading and controlled release from m-MS. In addition, the effect of drug loading and release on textural properties of m-MS such as surface area, pore diameter and pore volume was investigated. The synthesized compound was studied by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Brunauer– Emmett– Teller (BET) surface area analysis, transmission electron microscopy (TEM) and Uv-vis spectrophotometer. The low angle XRD, BET and TEM results showed that magnesium silicate contained 2D hexagonal honeycomb pore channels with uniform and homogeneously distributed mesopores of the same size. The m-MS demonstrated large specific surface area by about 504 m2/g and after adsorption of ibuprofen, the N2 adsorbed volume decreased obviously, and the corresponding BET surface area, pore size and pore volume changed from the 504 m2/g, 4. 6 nm, 0. 44 cc/g (550 º C) to 225 m2/g, 1. 2 nm, 0. 21 cc/g (550 º C drug loaded) respectively. This study revealed that m-MS has the ability to drug loading and controlled release of ibuprofen and can be used as a novel drug delivery system.

Study catalytic effect of CeO2 nanoparticle on thermal decomposition of ammonium perchlorateABSTRACTThis work studied on the thermal decomposition of ammonium perchlorate activated by addition of commercial CeO2 nanoparticles. CeO2 nanoparticles were characterized by X-ray diffraction (XRD) and transition electron microscope (TEM). The TEM study revealed that the majority of CeO2 particles are of 10– 30 nm in size. The catalytic activities of CeO2 nanoparticles on the thermal decomposition of ammonium perchlorate were investigated by thermogravimetric analysis (TGA) coupled with differential scanning calorimeter (DSC). The results imply that the catalytic performance of CeO2 nanoparticles is significant and the decrease in the thermal decomposition temperature and the increase in the heat decomposition AP. So that, adding 2 Wt. % of CeO2 nanoparticles to AP decreases the thermal decomposition temperature from 423. 89 to 330. 89 ° C. Also, Adding 2 Wt. % of CeO2 nanoparticles to AP increases the heat decomposition from 835 to 1517. 22 J/g.

In the present study, the effect of different cooling rate on microstructure and corrosion behavior of Mg-5Zn-1Y-0. 1Ca biomedical alloy are investigated. Microstructure observations using optical and scanning electron microscopes showed that the alloy contains α-Mg as the matrix, and Mg3YZn6 and Ca2Mg6Zn3 intermetallic precipitations, having lamellar morphology formed mostly at the grain boundaries. Also microstructure results showed that with increasing cooling rate, the continuity of precipitations increase in grain boundary and inter dendritic zones. The polarization test, as well as the immersion result, confirmed that increasing the cooling rate does not always improve the corrosion properties, and it seems there is an optimal cooling rate resulting in minimum corrosion rate. Abstract: In the present study, the effect of different cooling rate on microstructure and corrosion behavior of Mg-5Zn-1Y-0. 1Ca biomedical alloy are investigated. Microstructure observations using optical and scanning electron microscopes showed that the alloy contains α-Mg as the matrix, and Mg3YZn6 and Ca2Mg6Zn3 intermetallic precipitations, having lamellar morphology formed mostly at the grain boundaries. Also mi...

In this research work, laser scribed technique has been regarded to synthesize graphene on the surface of a DVD and manufacture graphene super capacitors. For this purpose, first, by Hummers method, graphite was converted to graphene oxide (GO) in an acidic environment containing Sodium nitrate, Potassium permanganate and sulfuric acid. Centrifuges and ultrasonic devices were utilized for the homogenization of graphene oxide solution. GO homogeneous solution was applied on the surface of specific DVDs and the set was dried at room temperature. For GO reduction and transform it into graphene, a suitable laser, with programming of super capacitor particular pattern was used. By applying an energy with the amount of resonance frequency of graphene and oxygen bond, the laser broke the connection and the reduction action and reaching to graphene was done. In this study, the process of graphene synthesis and applying the super capacitor specific pattern were carried out in single step that is the biggest advantage of laser scribed graphene (LSG) method. In present study, TEM was utilized to examine the layered structure of GO, SEM was used for microstructural studies, two tests of cyclic voltammetry (CV) and galvanostatic charge/discharge (CC) were applied to study the performance and power of energy storage in super capacitors, the XPS was used to investigate elements present in the layer applied on DVD, and the Raman spectroscopy was applied to investigate the quality of prepared graphene through studying G and D peaks.

The kinetics of electrophoretic deposition is influenced by various factors. Hamakr summarized them on five parameters such as suspension concentration, electric field on the suspension, the surface area of the electrodes, electrophoretic mobility, and the process time. The electric field in the suspension can be changed using the electric potential applied between the electrodes and electrode distance change. Since the suspensions is a non-ohmic resistance, these two parameters will not be the same. The change of electric field using each of these two parameters causes kinetic equations change. In long distances electrodes and poor electrical potential, kinetic equations are based on electrical resistance more accurately. In the strong fields and low electrode distance kinetic equations based on equivalent conductivity are more accurate. The results of this study showed that, in the electric field 70V/cm Ferrari et al. equation and in the electric field 25V/cm Sarkar and Nicholson equation have accuracy of less than 0. 01 and less than 0. 1, respectively.

Production efficiency and energy consumption are two important factors in electrochemical synthesis of potassium ferrate particles. In this research, the effects of different parameters including applied current density, KOH electrolyte concentration and its temperature on production efficiency and energy consumption have been studied. The condition of optimized production has achieved in current density of 40 mA. cm-2, 13M KOH electrolyte with temperature of 70 oC for two hours. In this situation, the production efficiency was 84. 63% and the energy consumption was 5. 05 kwh/kg. In next step, the effect of time duration on production efficiency, purity, formed phases and the size of potassium ferrate particles has been investigated in optimal condition. The results showed that due to decomposition of potassium ferrate particles with time, iron hydroxides and oxides components have been formed which reduces the purity and production efficiency. The sizes of potassium ferrate particles were measured by two method of Debye-Scherrer and modified Debye-Scherrer. This revealed that the size of potassium ferrate particles increases as time passes.