[Show abstract][Hide abstract] ABSTRACT: Characteristics of NOx removal combining dielectric barrier discharge (DBD) plasma with selective catalytic reduction (SCR) by C3H6 were investigated under the conditions of high NOx concentration and high space velocity at various temperatures. Experiment results show that there were no obvious removal of NOx and NO in the only C3H6-SCR system and only DBD system individually. But the high NOx removal rate was achieved in C3H6-SCR cooperating with DBD plasma system. Especially NOx removal rate can reach up to 88.5% at 150 °C simulating diesel engine exhaust temperature. It can be seen that when discharge comes into being, the catalystic activity was enhanced with discharge strengthened, so that the NOx was almost completely removed. In the course of NOx removal, DBD played an important role in oxidizing NO to NO2 and activating C3H6 and catalysts to reduce NOx.
No preview · Article · Aug 2010 · Japanese Journal of Applied Physics
[Show abstract][Hide abstract] ABSTRACT: With the assistance of dielectric barrier discharge (DBD) plasma, selective catalytic reduction of NO <sub>x</sub> by ethanol over Ag / Al <sub>2</sub> O <sub>3</sub> catalysts was studied. Experimental results show that NO <sub>x</sub> conversion was greatly enhanced due to the presence of DBD plasma at lower temperature. By varying the DBD voltages or power in 13 kHz frequency at different temperatures, NO <sub>x</sub> conversion was increased to 40.7% from 6.4% at 176 ° C , even to 66.8% from 17.3% at 200 ° C . NO <sub>x</sub> conversion could even be improved to 90% at temperature above 255 ° C . It was proposed that nonthermal plasma generated by dielectric barrier discharge reactor was very effective for oxidizing NO to NO <sub>2</sub> under excess O <sub>2</sub> conditions, which possesses high reactivity with C <sub>2</sub> H <sub>5</sub> OH to yield C <sub>x</sub> H <sub>y</sub> N <sub>z</sub> O compound. By reacting with C <sub>x</sub> H <sub>y</sub> N <sub>z</sub> O compound and oxygen, NO <sub>x</sub> is converted to N <sub>2</sub> at low temperatures.
No preview · Article · Aug 2009 · Journal of Applied Physics
[Show abstract][Hide abstract] ABSTRACT: In the present work, graphite grains of different sizes were added into the electrolyte to prepare ceramic coatings on aluminum by plasma electrolytic oxidation (PEO). Scanning electron microscopy (SEM) coupled with an energy dispersive X-ray analysis system (EDX), Raman spectroscopy and X-ray diffractometer (XRD) were used to characterize the coatings. A three-electrode system was used to evaluate the corrosion performances of the coatings in a 3.5 wt.% NaCl solution. It was found that the morphology and corrosion performance of the coatings were significantly influenced by the size of the graphite grains. Compared with bigger graphite grains, finer ones were involved in the oxidation process and embedded within the ceramic coatings, which made the coatings less porous and more compact. Thus, the corrosion resistance of the coatings with embedded graphite grains was greatly improved.
No preview · Article · Mar 2009 · Current Applied Physics
[Show abstract][Hide abstract] ABSTRACT: Plasma electrolytic oxidation (PEO) process was carried out on magnesium alloy with a pulsed direct current (dc) power source at high and low frequencies. The morphology and phase composition of the coatings were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion performances of the different coatings were evaluated via a three-electrode system in a 3.5-wt.% NaCl solution. It was detected that the PEO coatings were mainly composed of MgF2 and Mg3(PO3)2 phase. Coatings produced at relative high frequency had smaller pore size and looked much denser than those at low frequency. As a result, they performed better corrosion resistance in the present corrosive solution. These experimental results could be ascribed to the formation mechanism of the PEO coatings: lower frequency provided longer time for one single pulse, which induced continuous discharge.
No preview · Article · Nov 2008 · Journal of Materials Processing Technology
[Show abstract][Hide abstract] ABSTRACT: The diamond thin films were deposited on silicon substrates under invariable conditions of process pressure, substrate temperature negative direct-current (dc) bias of substrate and microwave power while the rations of methane (CH4) to hydrogen (H2) changing from 3% to 5% and 9% using electron-cyclotron-resonance microwave plasma-assisted chemical vapor deposition technique (ECRCVD). In situ Fourier transform infrared spectroscopy (FTIR) have been used to study the plasma species absorbed on the substrate surfaces as well as the species above the substrates surfaces both before and during the nucleation and film growth. It is demonstrated that these techniques can provide useful information on the early stages of diamond growth. When correlated with film properties measured by Raman spectroscopy and scanning electron microscopy, the results from FTIR indicate that the absorption of the graphitic and diamond phases are related to the ratio of CH4 to H2 and can be identified at the early stages of film growth.
No preview · Article · Jun 2008 · Guang pu xue yu guang pu fen xi = Guang pu
[Show abstract][Hide abstract] ABSTRACT: Highly oriented VO2 thin films were deposited on sapphire substrate and [C8H17O]8 PcNi thin films were spin-coated onto VO2 thin films. The microstructure of VO2 thin films was studied with XRD. The phase transition was observed and the change in the optical properties of the PcNi/VO2 multilayer-films were investigated with infrared spectrometer. It was found that the mid-infrared transmittance of the complex films in the wavelength range 1.5 to 5.5 mm raised with PcNi coating. The thermochromism of PcNi/VO2 films did not changed compared with VO2 films and the transition temperature was the same as that of VO2. It can be anticipated that the optical limiting property of PcNi/VO2 films will be superior to that of VO2 thin films or PcNi thin films.
No preview · Article · Nov 2007 · Guang pu xue yu guang pu fen xi = Guang pu