Residual Stresses VII, ICRS7
Magnesium - Science, Technology and Applications
Eco-Materials Processing & Design VI
Silicon Carbide and Related Materials 2004
Materials Structure & Micromechanics of Fracture
Cross-Disciplinary Applied Research in Materials Science and Technology
Materials Science, Testing and Informatics II
Advances in Materials Manufacturing Science and Technology
Recrystallization and Grain Growth
Explosion, Shock Wave and Hypervelocity Phenomena in Materials
High Temperature Corrosion and Protection of Materials 6
Silicon Carbide and Related Materials 2003
摘要: Sub-micrometer diamond tube arrays are formed on freestanding diamond film via focused ion beam pattern technology and chemical etching method. First, the sub-micrometer holes are fabricated on Si substrate by using FIB milling method. Then, diamond film is grown by hot filament chemical vapor deposition method on patterned Si substrate. By controlling the deposition parameters, the diamond can be grown along the wall of holes and the diamond tubes in sub-micrometer scale are formed. Finally, Si substrate is etched by chemical etching method and the diamond tube arrays are fabricated on a freestanding diamond film. Scanning electron microscopy and Micro-Raman spectroscopy measurements are performed to characterize the structure and phase purity of diamond tubes. The electron emission properties from the diamond tube arrays are studied, the result presents that the enhanced emission property can be obtained from diamond tube arrays.
摘要: The field electron emission from carbon nanotube films on polycrystalline diamond films was investigated. The carbon nanotubes and diamond films on Si substrates were prepared by a conventional hot filament chemical vapour deposition. The films obtained were characterized by scanning electron microscopy and Raman spectroscopy. The field emission properties of the samples were measured in an ion-pumped vacuum chamber at a pressure of 10-6 Pa.. The experimental results showed that the field emission behaviours of carbon nanotubes/diomond films structure have greatly been improved as compared with carbon nanotubes and diamond films, respectively. A turn-on field of 1.0 V/µm and a maximum current of 500 µA at 1.5 V/µm were observed, which were lower than those of carbon nanotubes and polycrystalline diamond films, respectively. This improvement was attributed to the tip shape of sample surface, which provided an additional local increase in electric field at the tube ends.
摘要: By using radio frequency magnetron reactive sputtering system, (002)-oriented AlN film was deposited on W tip. The field emission from (002)-oriented AlN film on W tip was studied and compared with that from the bare W tip in a high vacuum (≤10-6 Pa) chamber. It indicated that the enhanced electron emission could be obtained from the (002)-oriented AlN film on W tip. The corresponding Fowler-Nordheim plot of AlN presented a nonlinear behavior in nature related the high resistivity of AlN. Furthermore, the current-electric field (I-E) curve presented excellent reproducibility checked by repeated measurements.
摘要: Carbon nitride nanotubes (CN-NT) thin films were prepared on Ni-Cr coated glass substrate by microwave plasma enhanced chemical vapor deposition at a relatively low temperature of 600～650 °C. The morphology of the films were observed by scanning electron microscopy. The microstructure of the film were analyzed by x-ray photoelectron spectroscopy, x-ray diffraction, and Raman spectroscopy. The characteristics of field emission of CN-NT thin films were measured. Experimental results indicate that the film structure and properties of the field electron emission are related to flow ratio of N2 to CH4. When the flow ratio of N2 to CH4 was 3.3, the obtained film had a better field electron emission characteristics. The turn-on field of the film was 3.7 V/µm . The current density was 413.3 µA/cm2 at an electric field of 8 V/µm.
摘要: In the present investigation a specially designed ceramic interlayer, which is able to supply suitable protection of the ZnS substrate against chemical attack by atomic hydrogen, and is helpful to reduce the thermal stress, has been developed. Nano-crystalline diamond films were successfully deposited on to the pre-coated multi-spectrum ZnS. It was found that diamond nucleation on the ceramic interlayer could be greatly enhanced by a metal or semiconductor mask placed on top of the pre-coated ZnS substrate, whereas diamond nucleation will not happen even by long time seeding in ultrasonic bath with fine diamond powder suspension. It was found that diamond nucleation is induced by the presence of the metal or semiconductor mask. To our knowledge this kind of phenomena of induced nucleation has not been reported. Detailed results and discussions were presented.
摘要: In this study, X-ray detectors with coplanar metal-semiconductor-metal structure, were fabricated employing high quality chemical vapour deposited (CVD) diamond film grown by a direct current arc jet plasma system. In which the electrical contacts with dimension of 25 µm in width with a 25 µm inter-electrode spacing, were patterned on the growth side of the diamond film using lift-off technology. The performance of the fabricated detectors was evaluated by steady-state X-ray illumination. The photoconductivity of the diamond detectors was found to linearly increase with increase in the X-ray photon flux. This demonstrates that high quality CVD diamond can be used for X-ray detectors.
摘要: Structure-designed free-standing diamond films have been fabricated by DC plasma jet method. The different dominant crystalline surface distributions were obtained under different deposition conditions. The as-grown films were polished by thermal chemical method. For the same crystalline structure, the removal rate was strongly affected by polishing parameters, such as polishing temperature, polishing time and applied pressure. The experimental results also showed that the dominant surface distribution in the films affected the polishing removal rate very much.
摘要: Interfaces between Mo substrate and free-standing diamond films prepared by DC arc plasma jet operated at gas recycling mode were investigated, including for the first time used and multi-time used substrate. The morphology, phase composition and bonding state of elements in the interface between substrates and diamond films were examined by optical microscopy, XRD and XPS. The profiles of carbon concentration of Mo substrates were measured by GDOES. It showed that Mo2C and MoC were formed on the first time used Mo substrate, and MoC was found on diamond films nucleation side after detachment. It suggested that MoC was peeled off from Mo substrate. The stable Mo2C on Mo substrate was formed after multi-time use of Mo substrate. However, MoC has not been found on it. The thickness of carburizing layer on the first time used Mo substrate is up to 30µm, and the carburizing layer on the multi-time used substrate is much thicker than that on the first used. The amorphous carbon in the surface of the substrate and nucleation side of diamond films was found by XPS, including for the first time used and multi-time used substrate.
摘要: The tetrahedral amorphous carbon films are attracting materials because of their properties similar to diamond, such as high hardness, resistivity, optical transparency, chemical inertness and low coefficient of friction. These properties make it ideal for wear resistance application on cutting tools, automotive component, aerospace components and orthopedic prosthesis etc. In this paper the structures, mechanical properties and wear resistance of the tetrahedral amorphous carbon films deposited on silicon under lower pulse bias voltage by filtered catholic vacuum arc deposition system have been investigated. The high quality tetrahedral amorphous carbon film has been obtained. The hardness and elastic modulus of the low stress tetrahedral amorphous carbon films are higher than 60Gpa and 380Gpa respectively determined by nano indentation tests. The friction performance of the tetrahedral amorphous carbon films was also studied by SRV tests, the results show: the tetrahedral amorphous carbon films have much lower wear rate than that of silicon substrate.