A sheet plasma is generated by a mesh anode and a single hot-filament cathode with a DC power supply, and its characteristics are experimentally investigated. The sheet plasma is observed to locate around the anode. B...A sheet plasma is generated by a mesh anode and a single hot-filament cathode with a DC power supply, and its characteristics are experimentally investigated. The sheet plasma is observed to locate around the anode. Both electron density and electron temperature derived from the average energy of the energetic electrons in nitrogen are estimated to be 10s cm^-3 and 20- 40 eV, respectively, using the optical emission spectroscopy （OES） method based on a kinetic model of low-pressure nitrogen discharge. The electron density, electron temperature and their spatial distributions are found to be affected by the supplying voltage on the anode（70 V to 300 V）, filament temperature （600℃ to 780℃） and gas pressure （2 Pa to 20 Pa）. By adjusting these parameters the discharge status can be easily controlled.展开更多
Plasma electrolytic oxidation （PEO） coatings, formed under various anodic voltages （320-440 V） on biomedical NiTi alloy, are mainly composed of γ-AI203 crystal phase. The evolution of discharging sparks during th...Plasma electrolytic oxidation （PEO） coatings, formed under various anodic voltages （320-440 V） on biomedical NiTi alloy, are mainly composed of γ-AI203 crystal phase. The evolution of discharging sparks during the PEO process under different anodic voltages was observed. The surface and cross-sectional morphologies, composition, bonding strength, wear resistance and corrosion resistance of the coatings were investigated by scanning electron microscopy （SEM）, thin-film X-ray diffraction （TF-XRD）, energy dispersive X-ray spectrometry （EDS）, surface roughness, direct pull-off test, ball-on-disk friction and wear test and potentiodynamic polarization test, respectively. The results showed that the evolution of discharging sparks during the PEO process directly influenced the microstructure of the PEO coatings and further influences the properties. When the anodic voltage increased from 320 V to 400 V, the corrosion resistance and wear resistance of the coatings slowly increased, and all the bonding strength was higher than 60 MPa; further increasing the anodic voltages, especially up to 440 V, although the thickness and γ-AI203 crystallinity of the coatings further increased, the microstructure and properties of the coatings were obviously deteriorated.展开更多
基金supported by National Defence Research Foundation of China (No.A1420060181)
文摘A sheet plasma is generated by a mesh anode and a single hot-filament cathode with a DC power supply, and its characteristics are experimentally investigated. The sheet plasma is observed to locate around the anode. Both electron density and electron temperature derived from the average energy of the energetic electrons in nitrogen are estimated to be 10s cm^-3 and 20- 40 eV, respectively, using the optical emission spectroscopy （OES） method based on a kinetic model of low-pressure nitrogen discharge. The electron density, electron temperature and their spatial distributions are found to be affected by the supplying voltage on the anode（70 V to 300 V）, filament temperature （600℃ to 780℃） and gas pressure （2 Pa to 20 Pa）. By adjusting these parameters the discharge status can be easily controlled.
基金the financial support from the National Natural Science Foundation of China (Grant No. 51101085)the National Natural Science Foundation of Jiangxi Province (Grant No. 20114BAB216014)+1 种基金the Science and Technology Plan Projects of Jiangxi Province (Grant No.20111BBG70007-2)the Science and Technology Plan Projects of Department of Education of Jiangxi Province (Grant No.GJJ12450)
文摘Plasma electrolytic oxidation （PEO） coatings, formed under various anodic voltages （320-440 V） on biomedical NiTi alloy, are mainly composed of γ-AI203 crystal phase. The evolution of discharging sparks during the PEO process under different anodic voltages was observed. The surface and cross-sectional morphologies, composition, bonding strength, wear resistance and corrosion resistance of the coatings were investigated by scanning electron microscopy （SEM）, thin-film X-ray diffraction （TF-XRD）, energy dispersive X-ray spectrometry （EDS）, surface roughness, direct pull-off test, ball-on-disk friction and wear test and potentiodynamic polarization test, respectively. The results showed that the evolution of discharging sparks during the PEO process directly influenced the microstructure of the PEO coatings and further influences the properties. When the anodic voltage increased from 320 V to 400 V, the corrosion resistance and wear resistance of the coatings slowly increased, and all the bonding strength was higher than 60 MPa; further increasing the anodic voltages, especially up to 440 V, although the thickness and γ-AI203 crystallinity of the coatings further increased, the microstructure and properties of the coatings were obviously deteriorated.
