List of articles (by subject) meso/micro/nano fabrication
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Open Access Article
1 - Field Performance of Inlet Liner for Centrifugal Slurry Pump Manufactured by NR/PBR Nanocomposite
Puya Afsharjahanshahi Seyed Yousef Ahmadi-Brooghani Mehdi Raghebi Mohammad Ali KarimiCentrifugal slurry pumps are being used in many mineral companies to transport mineral materials. These materials are mainly abrasive and the liner of these pumps are eroded during their working life. Zinc oxide (ZnO) are usually used for enforcing rubber material but, MoreCentrifugal slurry pumps are being used in many mineral companies to transport mineral materials. These materials are mainly abrasive and the liner of these pumps are eroded during their working life. Zinc oxide (ZnO) are usually used for enforcing rubber material but, the ZnO is harmful to the environment. Nano ZnO (n-ZnO) particles seem to purvey higher activity. In this work, the inlet liner of a centrifugal slurry pump was fabricated with n-ZnO that decreases environmental concerns and improves its wear life. The composite of inlet liner is made of Natural rubber (NR) and Polybutadiene rubber (PBR). For determining the optimal dosage of n-ZnO within the composite, mechanical properties for rubber compounds comprising 1-2 unit(s) n-ZnO, were investigated comparing to those of the compound with 5 units conventional ZnO (c-ZnO). It was found that optimal amount of n-ZnO was 1 unit which it was enough to give equivalent or better mechanical properties compared to one containing a higher amount of, namely 5 units, c-ZnO in the composite. In addition, field-emission scanning electron microscopy (FESEM) photo showed that n-ZnO particles were homogeneously dispersed in the composite. Finally, two inlet liners were manufactured, one of them was with 1 unit of n-ZnO (n-liner) and the other one with 5 units of c-ZnO (c-liner). These two liners were used in service in a plant. The field study showed that the life of n-liner was 1/3 unit more than the life of c-liner and n-liner face has been worn less than c-liner one. Manuscript profile -
Open Access Article
2 - Micro Wire Electrical Discharge Machining of MEMS Structures with Optimized Dimensional Deviation
Mohammad Tahmasebipour Younes Tahmasebipour Ali VafaieMetal-based microelectromechanical systems are widely used in applications such as micro-energy harvesters, micro-heat exchangers and micro-electromagnetic that require high strength and flexibility. In the fabrication of such systems, micro wire electrical discharge ma MoreMetal-based microelectromechanical systems are widely used in applications such as micro-energy harvesters, micro-heat exchangers and micro-electromagnetic that require high strength and flexibility. In the fabrication of such systems, micro wire electrical discharge machining (MicroWEDM) is majorly used. This paper studies the effect of the MicroWEDM process parameters on the dimensional deviation of machined MEMS structures including microcantilevers and micro-beams using the Taguchi method. Using optimal levels of the parameters including pulse duration (0.8 µs), cutting speed (8.4 mm/min), voltage (17 V) and wire tension (0.5 kg), the dimensional deviation is reduced about 8.65 times compared with the average of experiments results. The order of effect importance of the process parameters on the dimensional deviation of microstructures obtained by the ANOVA analysis of S/N ratios is as follows: pulse duration, wire tension, process voltage and cutting speed. Dimensional deviation of the micro-features was reduced to 1 μm using the optimal levels of the process parameters. Manuscript profile -
Open Access Article
3 - Preparation of Nitrogen-Doped Graphene Aerogel/Epoxy Nanocomposites and Experimental Study of Mechanical Properties
ali kordi saeed adibnazari Ali Imam mohammad najafi maryam ghasabzadeh saryazdiNitrogen-Doped Graphene Aerogel (N-GA) nanomaterials can significantly improve the functional efficiency of polymer composites due to its three-dimensional structure and suitable physical properties. The preparation process affects the performance improvement. In this s MoreNitrogen-Doped Graphene Aerogel (N-GA) nanomaterials can significantly improve the functional efficiency of polymer composites due to its three-dimensional structure and suitable physical properties. The preparation process affects the performance improvement. In this study, the effect of preparation method and the mechanisms affecting the strength behavior of Nitrogen-doped Graphene Aerogel/Epoxy (N-GA/E) nanocomposites was investigated. For this purpose, nanoparticles of Graphene Oxide (GO) were produced using Hummers’ method; then, the N-GA was synthesized using the hydrothermal method and the freeze-drying process. The characterization experiments were used in order to confirm the structure and quality of the synthesized nanomaterials. Then, specimens of nanocomposite were prepared by adding weight percentages of 0.05, 0.1, 0.2, 0.5, 1, and 2 from the synthesized N-GA to the epoxy resin. In other preparation processes, N-GA/E nanocomposite specimens were produced using auxiliary solvents. After tensile tests, the best strength performance was observed in the specimens with the preparation process in which acetone solvent was used. The tensile strength and modulus of these nanocomposite specimens have increased by 23% and 20% compared to neat epoxy specimens, respectively. Also, the optimal weight percentage of N-GA nanomaterials for distribution in epoxy is 0.1 wt.%. Microscopic images of the fracture surfaces of the specimens used in the tensile test showed that the placement of N-GA porous plates in epoxy with the creation of the mechanism for micro crack formation led to more energy absorption during the stretching process of the N-GA/E nanocomposites. Manuscript profile -
Open Access Article
4 - Label-Free Perfect Separation of Michigan Cancer Foundation-7 Cells from White Blood Cells using Both Wall-Induced Lift and Dielectrophoresis Forces
Alireza Alaghemand Ali FattahA microchannel device was designed and utilized to separate Michigan Cancer Foundation-7 cells from white blood cells using both wall-induced lift and di-electrophoresis forces. Using COMSOL Multiphysics simulator, the label-free separation process is performed based on MoreA microchannel device was designed and utilized to separate Michigan Cancer Foundation-7 cells from white blood cells using both wall-induced lift and di-electrophoresis forces. Using COMSOL Multiphysics simulator, the label-free separation process is performed based on the radius size of the particles. The best performance of the structure is obtained with the efficiency of 100% and 99% for cancer and white blood cells separation processes, respectively. For the proposed microfluidic structure, in addition to the highest available efficiency and high separation speed of 12 um/s, the low DC voltage of 6 V is applied, which causes negligible damage to the blood cells. Manuscript profile -
Open Access Article
5 - Micro Electropolishing of the MEMS Metallic Structures Fabricated by the Micro WEDM Process
Mohammad Tahmasebipour Younes Tahmasebipour Mahya Boujari Aliabadi Shadi EbrahimiIn this study, the micro electro-polishing method was employed to improve the surface quality of microbeams machined by the micro WEDM method and to remove the recast layer. This approach changes the dimensions of the microbeams, as a result of the electrochemical corro MoreIn this study, the micro electro-polishing method was employed to improve the surface quality of microbeams machined by the micro WEDM method and to remove the recast layer. This approach changes the dimensions of the microbeams, as a result of the electrochemical corrosion, in addition to the elimination of the recast layer. To diminish the impact of this process on the dimensional deviation of the fabricated microbeams, the influence of the micro electro-polishing process parameters such as voltage, duration, cathode diameter, and electrolyte composition on the dimensional deviation of microbeams was studied using the Taguchi method. The optimum values of process parameters were determined by the S/N ratios analysis, and the order of parameters importance was determined through analysis of variance of the S/N ratios. It was found that the optimal levels of the process parameters are voltage of 2 V, process duration of 20 s, cathode diameter of 50 mm, and electrolyte composition of 25-5-40 ml (sulfuric-phosphoric-water) within the range of experiments. By using the optimum values of the parameters, the dimensional deviations were found to be 5.23 times lower compared to the average of the results. The importance of process parameters was found to follow this order: electropolishing duration, electrolyte composition, cathode diameter, and process voltage. Manuscript profile -
Open Access Article
6 - Study on the Thermophysical Properties of Hybrid Nanofluid Based on Aircraft De/Anti-Icing Fluid at Low Temperatures
Nasim NayebpashaeeThis work involves an experimental study of the thermophysical properties of hybrid nanofluids of TiO2 and graphene in a binary mixture of water and ethylene glycol. Hybrid nanofluid samples with different volume fractions (0.05-2.5%) were prepared by dispersing equal v MoreThis work involves an experimental study of the thermophysical properties of hybrid nanofluids of TiO2 and graphene in a binary mixture of water and ethylene glycol. Hybrid nanofluid samples with different volume fractions (0.05-2.5%) were prepared by dispersing equal volumes of TiO2 and graphene nanoparticles in a binary mixture of water and ethylene glycol in the ratio of 50-50% by volume. The thermal conductivity, surface tension, and dynamic viscosity of the hybrid nanofluids were measured at temperatures ranging from 253 K to 303 K. The experimental results showed that the low concentration samples exhibited shear thinning non-Newtonian behavior, while the high concentration samples exhibited shear thickening non-Newtonian behavior. The measurements showed that the thermal conductivity of the nanofluids increases by up to 41.93% with increasing nanoparticle concentration and temperature. The surface tension improves by 43.61%, 39.77%, and 51.98% at concentrations of 2.5%, 2%, and 2% by volume at temperatures of 258.15 K, 268.15 K, and 283.15 K, respectively. In terms of aircraft deicing fluid performance, the addition of TiO2 and graphene nanoparticles at less than 0.5% by volume contributes to the improvement of aircraft deicing fluid performance. Manuscript profile