جستجوی مقالات مرتبط با کلیدواژه "اسید شویی" در نشریات گروه "مواد و متالورژی"

This research used multi-walled carbon nanotubes with a 30 to 50  nm diameter and an approximate length of 6  µm to store hydrogen gas by the volumetric method. Carbon nanotubes' structure, shape, and physical properties were investigated by X-ray diffraction analysis, transmission electron microscopy, and infrared spectroscopic analysis. To investigate the hydrogen storage capacity in carbon nanotubes, the effect of two parameters, namely acid washing and YAG: Nd laser irradiation, were studied. The results showed that acid washing and laser irradiation increased the specific surface area of carbon nanotubes by 59%  and 100%, respectively. Studies also showed that purified carbon nanotubes stored 0.3 wt.% hydrogen, which revealed a 75% increase compared to the original nanotubes. Also, laser irradiation with different times changed the storage capacity of nanotubes. The optimal value of laser irradiation was obtained to be 90  minutes, which increased the storage capacity of hydrogen gas in nanotubes to 1.1 wt.%.

Alfa layer due to the hot forging of the titanium alloy is removed using the acid pickling operation. Because of the interaction between the effective parameters, investigation and optimization of the effective parameters needs experimentation and modeling methods. In this research effect of the temperature, operation time and percent of the hydrofluoric and nitric acids on the surface roughness and depth of cutting are modeled and optimized. First the experiments are designed using taguchi method and implemented. Then the process is modeled by an artificial neural network and the effect of the parameters on the surface roughness and depth of cutting are investigated. Next by combining the artificial neural network with genetic algorithm the process is optimized. Results show that a Multilayer Feed forward network with Levenberg-Marquardt backpropagation learning algorithm and ten nods in the hidden layer could model the operation precisely. Increasing the temperature and hydrofluoric acid percent cause to increase the depth of cutting. Nitric acid percent and operation temperature have interaction in affecting on the amount of depth of cutting. Operation time have no affect on the roughness. Increasing the temperature at low percent of hydrofluoric acid cause to decrease the roughness however it increases at high percent of hydrofluoric acid.