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The Si/Al ratio is one of the effective parameters on the physicochemical properties of nanostructured LaAPSO-34 catalysts. Utilization of optimum ratio of Si/Al could significantly enhance the efficiency of these molecular sieves in the methanol to olefins conversion. To this aim, a series of nanostructured LaAPSO-34 catalysts with different Si/Al ratios were synthesized via hydrothermal method and characterized by XRD, FESEM, EDX, BET and FTIR techniques. XRD results showed that the growth of crystalline network is not considerable in the low Si/Al ratio, while the crystallinity has increased by increasing of this ratio. FESEM images revealed that by increasing Si/Al ratio, cube-shaped chabazite particles completely were formed. However, rough on the surface of the catalyst particles was observed in the high ratio of Si/Al. EDX analysis confirmed the presence of elements of this zeolite and also showed a uniform distribution of components. BET results showed that by increasing of Si/Al ratio from 0.1 to 0.3, specific surface area of the nanostructured LaAPSO-34 catalysts increased. FTIR spectrums confirmed framework vibrations of chabazite in different Si/Al ratios. Catalytic performance tests showed that by increasing of reaction temperature, methanol conversion increased. Increasing the Si/Al ratio from 0.1 to 0.3 led to the enhancement of the LaAPSO-34 performance and catalyst stability.

The Effect of Fe addition (0.2-2wt%) on the wear behavior of Al-(5-13)Si alloys was investigated. The pin-on-disk wear tests were conducted at room temperature, under normal load of 45N, sliding speed of 0.13 m/s for sliding distance of 1000m. The results showed that bellow a critical Fe content (1.2wt% in this research), Si addition improved the wear resistance. In this regard, the wear rate of Al-13Si-0.8Fe alloy was observed to be less than 50% of Al-5Si-0.8Fe. This could be attributed to the fine distribution of hard AlFeSi platelets in interdendritic regions that increased the hardness and decreased the subsurface deformation and asperities adhesion. So, controlled delamination within tribolayer as well as abrasive wear could be proposed as the main wear mechanisms. Formation of large primary AlFeSi platelets at the iron content of more than critical value, however, facilitates the initiation and propagation of subsurface cracks and instability of tribolayer. This led to the higher delamination and abrasive wear with higher Si containing alloys.

In this study the experiments was done in order to product silicide component as a protective coating with a mixture powder Mo-Si-C In situ cladding on the nickel surface. Before applying cladding، was ball-milling processes for activating mixture powder and then by the product using electrodes of powder mixtures by doing welding processes was formed coating with a thickness of 1mm by sharp boundary with substrate. The cross-section microstructure of specimens was studied by optical microscopy and scanning electron microscopy (SEM). The specimens were characterized by X-ray Diffraction (XRD). Phase detecting specimens indicate that the addition of 2wt% graphite powder to the mixture formed Mo2Ni3Si، NiSi and small amount of MoSi2 phase and SiC reinforcement phase. Evaluation the results of the reciprocating wear tests showed that by addition 2% weight graphite in the mixed powder and formation SiC، the good resistance abrasion is done to change the plastic form and loss weight during the wear process. Also the hardness test showed that by the cladding of mixture powder increases hardness to 850 HV0. 2.

In this research properties of Single-Step High temperature-High activity Si-modified Nickel Aluminide coating on superalloy Inconel 100 at 1000 and 1100˚C have been investigated. Si-modified NiAl coating were prepared using 5 and 10 percent mass of Al and Si powders as well as Al2O3 and NH4Cl activators. Microstructure, phase distribution and coating composition of as-coated specimens were analyzed by using OM, SEM equipped with EDS/WDS and XRD. The results showed that co-precipitation of Al and Si using Single-Step High Temperature-High Activity process can be achieved. By reducing Al and Si amount in the pack from %10 to %5 in mass, the coating depth enriched by Si decrease from 50 to 20μm. In 1 hour, With %10 in mass pack hyperstoichiometric NiAl phase with more than %50 at of Al was formed while after 1 and 3 h aluminizing with %5 in mass pack, hypostoichiometric NiAl phase with less than %50 at of Al was formed. Micro hardness test results have shown that hardness of formed surface coating varies from 449 VHN in substrate to 1003 VHN in interdiffusion zone duo to presence of various carbides with complex composition.

This paper reports on the photo detection properties of graphene nano layer, based on the fabrication of graphene-Si Schottky diode. To fabricate this Schottky junction, a graphene nano layer has been deposited on Si substrate. The Si substrate is oxidized to 270 nm thickness and is patterned with a specific mask after Cr/Au deposition (the thickness of Cr/Au are 50 nm and 150 nm, respectively). The current-voltage (C-V) curves of the diode are analyzed under 670, 700 and 1100 nm illuminations and also under yellow light radiations. To investigate the photo detection properties of graphene nano layer in Schottky diode structure, 700 and 1100 nm radiations are also illuminated to the backside of the diode and then the photo-generated current under both front and back side illuminations are compared. The experiment results demonstrate that the generated currents in the front side mode and under 700 and 1100 nm illuminations have been increased about 23 and 17 times in comparison with the backside mode. This rise in the current shows the graphene effect in photo detection mechanism and also shows the great amount of photo generated current in graphene in the front side illuminations. The C-V curves of the diode under 670 nm and yellow light illuminations demonstrate not only the photo-generated current but also the photo voltage which shows graphene potential for being used as the solar cell. The optical properties of graphene are also discussed in this paper and many theories which can describe the generation of photo current in graphene are presented.

In this study, Mo-14Si-10B and Mo-57Si-10B (at%) elemental powders were separately milled using an attritor mill.Mechanically alloyed powders were agglomerated and annealed. Then, powders of Mo-Si-B as alloyed (with composites) and agglomerated (without composites) were plasma sprayed onto plain carbon steels. The samples, both coated and noncoated,were subjected to isothermal oxidation tests. Metallurgical characteristics of powders and coatings were evaluated by SEM and XRD. Plasma-sprayed Mo-Si-B coatings (with phases of MoSi2, Mo5Si3, MoB and Mo5SiB2) greatly improved the oxidation resistance of the plain steel substrates, but plasma-sprayed Mo-Si-B coatings (without any phases) did notsignificantly improve the oxidation rate of substrates. Also, the kinetics and composition of the oxide-scale have been found to depend on the alloy composition.

In this study, an attempt was made to synthesize Mo-Si-B multiphase alloy coatings using a combination of mechanical alloying (MA) and air plasma spraying (APS). Mo-14Si-10B (at%) elemental powders were milled using an attritor mill. Mechanically alloyed (MAed) powders as compacted buttons were annealed in an atmosphere controlled furnace at 1100ºC for different times. The annealed Mo–Si–B buttons were crushed, sieved and prepared for coating. Then, powders of Mo-Si-B as alloyed and agglomerated, were plasma sprayed under different conditions onto plain carbon steel. Metallurgical characteristics of powders and coatings were evaluated by SEM, OM, XRD and AAS. The results did not show any related intermetallics after MA. However, Molybdenum silicides were identified when the MAed powders were subjected to high temperature annealing over 10 h. Also, the critical parameters in APS to maintain the starting stoichiometry were identified; this included thermal spraying in an inert environment to minimize the oxidation of coatings. No intermetallic compounds could be identified when alloyed powders were sprayed.

An Al-Mg-Si-Cu alloy was subjected to tensile testing, both under solutionized and ECAE-ed conditions, using strain rates of 10-4 s-1 to 10-1 s-1 at temperatures of 25 $C to 325 $C to investigate the dynamic strain aging (DSA) phenomenon in the alloy. Negative strain rate sensitivity (m) and increasing ultimate tensile stress were observed in the DSA region with increasing temperature. Regarding the activation energy of the phenomenon, it was suggested that the process is controlled by the interaction of Mg atoms with mobile dislocations at lower temperatures of DSA occurrence while at higher temperatures, the aggregation of Mg atoms and precipitates of a second phase decreases the amount of Mg atoms in the solid solution, resulting in the inverse DSA effect. Moreover, it was shown that at temperatures greater than 250 $C, the ratio of post-uniform to uniform elongation increases with increasing temperature or with decreasing strain rate due to the solute drag of Mg atoms in the Al matrix. Processing the alloy by ECAE transferred the negative m values to lower temperatures and decreased the tendency to DSA at higher temperatures. Calculating the mentioned ratio for the ECAE-ed specimens revealed that the post-uniform elongation dominates the uniform elongation at all examined temperatures and strain rates. Also, it was found that for ECAE-ed specimens, the ratio is not so sensitive to variations of temperature and strain rate.