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Abstract- In the present paper, three different samples of alumina used as nanoparticles in the ethylene glycol suspension of alumina with volumetric concentration in the range . These samples have different surface properties, shape and size. The use of Al2O3/EG nanofluids as coolants in a double-tube heat exchanger has been studied under laminar flow conditions. The hot solvent inlet heat exchanger must be cooled down with a specified amount. At first, heat transfer relations between hot solvent and nanofluids as coolants have been investigated theoretically. Subsequently, heat transfer area and flow rate of coolant are optimized by using the nanofluids. In the present paper, heat transfer coefficient, overall heat transfer coefficient, friction factor, pressure drop and pumping power for Al2O3/EG nanofluids calculated.

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The main aim of this experiment is to investigate the effects of Nano-size Al2O3 on the mechanical properties and microstructure of multi-passes friction stir welding of Al 2024 lap joint. Nano particles were added into the joint line. A combination of rotational speed and travelling speeds were performed. Optical microscopy and scanning electron microscope were used to investigate the microstructure and fracture surface of samples respectively. Optimum condition (sample) was selected due to highest ultimate tensile strength (UTS). It was seen that sample which included Nano particles and fabricated by 1400 rev/min rotational speed and 16 mm/min travelling speed in second pass of continues welding had improvement in UTS in comparison to one pass welded sample of particle free and after that increasing the number of passes reduce the UTS. The average micro hardness of the sample which was particle rich were increased in comparison to particle free sample in nugget zone. Increasing the number of passes was not effect average micro hardness in nugget zone significantly. Grain sizes were reduced by 2 passes welding and after that no significant reduction has been seen.

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Cemented carbides are the most common cutting tool materials. To improve machining process, the surface of the cutting tools must be wear resitance with high hardness and chemical inertness. In recent years, several coatings have been developed for tungsten carbide. In this paper, the effect of TiN/TiCN/Al2O3 multicoatings on the performance of drilling process of spherodized cast iron was studied. The external layer is Al2O3 which has high resitance to wear and TiN was chosen as internal layer because of it excellent adhesion to the tungsten carbide surface. The intermediate layer was TiCN because of its compatibility with the other layers. At first, drills were prepared by machining process and then the triple layer coating was applied on the surface of tungsten carbide drills by chemical vapor deposition method. The coating process was performed under usual industrial condition. The thickness of the coatings was 10 micrometers. The wear of drills, the surface roughness and the hole diameter tolerance were investigated. The structure of coating and wear surface was studied by scanning electron microscopy. It was found that the multiple coating significantly improved the wear resistance of the drill compared to uncoated tolls. In addition, it was found that the surface roughness and hole diameter tolerances improved by drilling with coated tools. The reason of this would be the lower wear rate and resulting dimension stability of the coated tools. In addition, according ot wear surface structure, it was concluded that the mechanism of wear was abrasion.

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In recent years, many attentions have been paid to decrease of the weight of components in automotive, transport and aeronautical industries, in respect of reduction of energy consumption and environmental pollution. Therefore, low-density aluminum alloys reinforced with nanoparticles especially CNT and Al2O3 have been broadly considered for application in such industries due to high strength/weight ratio. In current work, Al-CNT-Al2O3 nanocomposite was produced by accumulative roll bonding (ARB) after 6 passes. CNT-Al2O3 composite with 1wt% multi-wall carbon nanotube (MWCNT) and 2wt% nano-alumina was prepared by ball milling process. The effect of the ARB cycles on the microstructure and mechanical properties of nanocomposite were studied by field emission scanning electron microscopy images (FESEM), X-ray diffraction data, tensile and micro hardness results. FESEM images showed the uniform distribution and high quality bonding of carbon nanotubes in the matrix. X-ray diffraction analysis indicated the composite nanostructure formation with the crystal size of 53.3 nm after 6 cycles of ARB compared to 77 nm of Al after pass 11. The results obtained by the tensile and hardness tests showed that at the end of ARB process, ultimate strength was 5.9 times, and hardness was 3 times more than those of the annealed aluminum.

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Since woven fabrics have uniqe characteristrics such as light weight, flexibility, high strength, etc. and they are also capable to be improved for mechanical properties by nano thechnology, it is expectal to gain more efficient composite using intrinsic properties of the ceramic nanoparticles and proper coating method. The uniqe properties of the nanoparticles such as high elastic modulus, high strength to weight ratio etc. as well as participating in defeat mechanisms agains external loadings, can be of the factors reinforcing the textiles. Al2O3-13%TiO2 coatings were deposited on Kevlar Fabric substrates from nanostructured powders using atmospheric plasma spraying (APS). A complete characterization of the feedstock confirmed its nanostructured nature. Coating microstructures and phase compositions were characterized using SEM, and XRD techniques. The microstructure comprised two clearly differentiated regions. One region, completely fused, consisted mainly of nanometer-sized grains of α-Al2O3 with dissolved Ti+4. The other region, partly fused, retained the microstructure of the starting powder and was principally made up of nanometer -sized grains of γ-Al2O3, as confirmed by FESEM. coatings were in average slightly lower than the values for nanostructured coating. The results of tensile testing on kevlar fabrics before and after coating showed that APS could improve tensile strength up to 60%. High velocity impact test (V50) performed on coated fabrics well indicated that their ballistic limit experienced a significant increase. In addition, the results of V50 showed revealed that APS can decrease final weight of new composite panel compared to plain polyetylen panel with identical protection level.

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 Micro-milling process as one of the most widely used methods of making parts due to the small size and their delicate properties in the process. In this study, micro-milling operations were performed on a titanium piece made of Ti6Al4V alloy using a tool with a diameter of 0.5 mm. The effect of nanoparticles used in lubricants on the surface roughness of the micro-milled workpiece is the most important characteristic studied in this research. In this research, experimental test methods and design and analysis of experiments by Taguchi method have been used to study the surface roughness during the process. Experimental tests to compare the role of lubrication in dry, wet and Minimum Quantity Lubrication (MQL) in different machining environments with lubricants containing nanoparticles and without nanoparticles and the effect of shear parameters on different characteristics of micro-milling of Ti6Al4V alloy is done. The results show that the use of Minimum Quantity Lubrication (MQL), especially with lubricants containing nanoparticles, increased the surface quality and had a more effective role in lubrication during micro-milling of Ti6Al4V alloy. Spindle speed and type of lubrication are the most effective parameters in Ti6Al4V alloy micro-milling.