Un-hydrogenated Diamond-like Carbon （DLC） films were prepared by pulsed laser deposition technique at different substrate temperature. The Raman spectra, the absorption and the photoluminescence spectra were measure...Un-hydrogenated Diamond-like Carbon （DLC） films were prepared by pulsed laser deposition technique at different substrate temperature. The Raman spectra, the absorption and the photoluminescence spectra were measured. The dependence of structure and phetoluminescence properties on deposition temperature were studied in detail. The experimental results indicate that the sp^2 sites form small clus ters that consist of both olefinic chains and aromatic ring groups within the sp^3 matrix. With raising deposition temperature,the optical band gaps increase from 1.87 to 2.85 eV. The main band of photoluminescence centered at around 700nm shifts to short wavelength, and the intensity of this band increases. The photoluminescence can be attributed to carrier localization within an increasing sp^2 clusters. It was clarified that the DLC films are ordered with increasing deposition temperature.展开更多
The pressure pulsation induced by the pumped periodic pulsation fluid is the main factor of causing fluid resonance and stimulating pipelines vibrations and noise. In order to reduce the f...The pressure pulsation induced by the pumped periodic pulsation fluid is the main factor of causing fluid resonance and stimulating pipelines vibrations and noise. In order to reduce the faults caused by the vibrations of pipelines, two aspects have been researched: one is to develop high quality filters, weaken and restrain the crest of pulsation pressure; the other is to design structural parameters of the piping network and eliminate the fluid resonance. Both need calculating the pressure pulsations of different structural parameters and frequencies, and knowing the amplitude frequency. In this paper the stiffness matrix technique is used for treating the coupling of subsystems of pipelines and calculating the pressure distribution of the piping network and it is tested by simulation and experiments.展开更多
The structure phase transformations of graphite and carbon black induced by pulsed laser were studied in this paper.Under irradiation with laser beam of 1.06 μm wavelength and power density of 106 W·cm-2,both gr...The structure phase transformations of graphite and carbon black induced by pulsed laser were studied in this paper.Under irradiation with laser beam of 1.06 μm wavelength and power density of 106 W·cm-2,both graphite structure and carbon black structure were changed obviously.The results of Raman analyses and Transmission Electron Microscopy(TEM)observations show that graphite transforms into nanodiamond about 5 nm and carbon black is graphitized.It is demonstrated that graphite is the intermediate phase in the transformation from carbon black to diamond,and graphite is easier to transform into diamond by laser irradiation than carbon black.展开更多
文摘Un-hydrogenated Diamond-like Carbon （DLC） films were prepared by pulsed laser deposition technique at different substrate temperature. The Raman spectra, the absorption and the photoluminescence spectra were measured. The dependence of structure and phetoluminescence properties on deposition temperature were studied in detail. The experimental results indicate that the sp^2 sites form small clus ters that consist of both olefinic chains and aromatic ring groups within the sp^3 matrix. With raising deposition temperature,the optical band gaps increase from 1.87 to 2.85 eV. The main band of photoluminescence centered at around 700nm shifts to short wavelength, and the intensity of this band increases. The photoluminescence can be attributed to carrier localization within an increasing sp^2 clusters. It was clarified that the DLC films are ordered with increasing deposition temperature.
文摘The pressure pulsation induced by the pumped periodic pulsation fluid is the main factor of causing fluid resonance and stimulating pipelines vibrations and noise. In order to reduce the faults caused by the vibrations of pipelines, two aspects have been researched: one is to develop high quality filters, weaken and restrain the crest of pulsation pressure; the other is to design structural parameters of the piping network and eliminate the fluid resonance. Both need calculating the pressure pulsations of different structural parameters and frequencies, and knowing the amplitude frequency. In this paper the stiffness matrix technique is used for treating the coupling of subsystems of pipelines and calculating the pressure distribution of the piping network and it is tested by simulation and experiments.
基金Supported by National Natural Science Foundation of China(No.50372043)Tianjin Science and Technology Committee(No.06YFJZJC01200).
文摘The structure phase transformations of graphite and carbon black induced by pulsed laser were studied in this paper.Under irradiation with laser beam of 1.06 μm wavelength and power density of 106 W·cm-2,both graphite structure and carbon black structure were changed obviously.The results of Raman analyses and Transmission Electron Microscopy(TEM)observations show that graphite transforms into nanodiamond about 5 nm and carbon black is graphitized.It is demonstrated that graphite is the intermediate phase in the transformation from carbon black to diamond,and graphite is easier to transform into diamond by laser irradiation than carbon black.
