Material science
shahab khameneh asl; reza golzarian; behnam salahimehr; ali fardi
Abstract
Platinum nanoparticles are widely used in the oil and gas industries, electronics, space tools, pharmaceutical industries, biomaterials and etc.Platinum catalysts are more active and selective than the other catalysts. In this regard, the preparation of a suitable alumina catalyst base and more effective ...
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Platinum nanoparticles are widely used in the oil and gas industries, electronics, space tools, pharmaceutical industries, biomaterials and etc.Platinum catalysts are more active and selective than the other catalysts. In this regard, the preparation of a suitable alumina catalyst base and more effective coating of platinum particles are presenting an important role in increasing the quality and efficiency of the catalyst. The purpose of this research is to prepare a high Specific surface area alumina base via aluminum anodizing and coating them with platinum particles. As a result, two steps of the work have been carried out, which are as follows: anodizing aluminum in an oxalic acid solution and optimizing its parameters to reach alumina nanotubes with controlled diameter, thickness and height. Subsequently, the research is resumed using scanning electron microscopy and data related to the special surface.In the next step, different amounts of platinum coatings using a suitable metal salt and solvent is deposited via an optimized electrochemical method.Finally, nanotubes with a diameter, thickness, height of about 60 nm, 20 nm, 15 μm, respectively were produced as the catalyst base.The optimized parameters include: applied voltage of 40 v DC and temperature range of 0-4 °C and the duration of anodizing for 7 h.The platinum coat array is masked on the substrate lithographically. The Samples are prepared using H2PtCl6.6H2O under an electrochemical 12V AC of 200 Hz with a sinusoidal waveform in a solution at a concentration of 8 mM in 150 seconds.The specific surface area was 3.16 m2/g and the absorbed gas volume was 0.728 cm3/g, absorption and desorption isotherm had a hysteresis suitable for catalytic activity.This knowledge was acquired in order to optimize the synthesis and coating conditions of the substrate with a suitable coating for catalytic applications and thermal knives.
Propulsion
mohamad ali amirifar; alireza rajabi; nooredin ghadiri masoom; zahra amirsardari; majid kamranifar
Abstract
In this research, the performance of a monopropellant hydrazine thruster in atmospheric conditions has been investigated experimentally. For this purpose, after designing and constructing the thruster according to the functional requirements of the thruster, a test was designed and after that, the desired ...
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In this research, the performance of a monopropellant hydrazine thruster in atmospheric conditions has been investigated experimentally. For this purpose, after designing and constructing the thruster according to the functional requirements of the thruster, a test was designed and after that, the desired thruster was tested in atmospheric conditions. The test results show that the tested thruster can generate 2000 pulses with a width of 0.5 seconds and a periodicity of one second with reproducibility. It was shown that the life of this thruster is more than 2000 pulses and the thruster was able to produce very small beats of 3 mNS in reproducibility. Also, comparing the results of the current thruster sample with the experimental results of other thrusters showed how by selecting the appropriate dimensions for the injector, catalyst chamber and nozzle, the characteristics of pressure rise time, minimum impulse, pulse centroid and pressure drop time in the Thruster can be well controlled. Reducing the injector diameter (by keeping the flow rate constant by increasing the injection pressure) reduces the impulse (within a constant pulse width) and increases the pressure rise time. Reducing the dimensions of the catalyst chamber also reduces the increase and decrease time of the pressure, resulting in a smaller pulse centroid.
