High-speed milling of titanium alloys is widely used in aviation and aerospace industries for its high efficiency and good quality.In order to optimize the machining parameters in high-speed milling TB6 titanium alloy...High-speed milling of titanium alloys is widely used in aviation and aerospace industries for its high efficiency and good quality.In order to optimize the machining parameters in high-speed milling TB6 titanium alloy,experiments of high-speed milling and fatigue were conducted to investigate the effect of parameters on 3D surface topography and fatigue life.Based on the fatigue fracture,the effect mechanism of surface topography on the fatigue crack initiation was proposed.The experiment results show that when the milling speed ranged from 100 m/min to 140 m/min,and the feed per tooth ranged from 0.02 mm/z to 0.06 mm/z,the obtained surface roughness were within the limit（0.8 μm）.Fatigue life decreased sharply with the increase of surface equivalent stress concentration factor.The average error of fatigue life between the established model and the experimental results was 6.25%.The fatigue cracks nucleated at the intersection edge of machined surface.展开更多
Parts of complex surface are widely used now in many fields, and their detection has caused much concern. In China many manufactories still carry on the traditional way of manual detection, which requires highly skill...Parts of complex surface are widely used now in many fields, and their detection has caused much concern. In China many manufactories still carry on the traditional way of manual detection, which requires highly skilled personnel and efficiency is low. Some large manufactories have imported auto-detecting equipments, which require CAD data on the parts, or just divide the surface into several approximate planes for automatic detection. Phased-array system is seldom used, and the cost is high. Besides, most of the systems have not considered the automatic sensitivity compensation of parts with varying thickness. To improve the detection quality and efficiency of nondestructive test (NDT) of parts of complex surface, this paper puts forward an integrated ultrasonic NDT system characterized by: (1) Use of ultrasonic measurement and reverse of curved surface to solve the CAD data problem; (2) Use of an automatic sensitivity compensation algorithm (based on the part’s modelling information obtained in surface reverse) to fit the variety of the thickness; (3) Use of template matching and pseudo-color imaging to improve the quality of detection results. The system features integration of low cost mature technologies, and is suitable for detection of various parts of different complex surfaces in medium-and-small enterprises. The test results showed that the system can automatically detect parts of complex surface successfully, and that the inspection result is good and reliable.展开更多
Spectroscopic ellipsometry (SE), photocarrier radiometry (PCR) and photoluminescence (PL) techniques were employed to measure the ultra-shallow junction (USJ) wafers. These USJ wafers were prepared by As+ ion implanta...Spectroscopic ellipsometry (SE), photocarrier radiometry (PCR) and photoluminescence (PL) techniques were employed to measure the ultra-shallow junction (USJ) wafers. These USJ wafers were prepared by As+ ion implantation at energies of 0.5-5 keV, at a dose of 1×1015 As+ /cm 2 and spike annealing. Experimentally the damaged layer of the as-implanted wafer and the recrystallization and activation of the post-annealed wafer were evaluated by SE in the spectral range from 0.27 to 20 m. The PCR amplitude decreased monotonically with the increasing implantation energy. The experimental results also showed that the PCR amplitudes of post-annealed USJ wafers were greatly enhanced, compared to the non-implanted and non-annealed substrate wafer. The PL measurements showed the enhanced PCR signals were attributed to the band-edge emissions of silicon. For explaining the PL enhancement, the electronic transport properties of USJ wafers were extracted via multi-wavelength PCR experiment and fitting. The fitted results showed the decreasing surface recombination velocity and the decreasing diffusion coefficient of the implanted layer contributed to the PCR signal enhancement with the decreasing implantation energy. SE, PCR and PL were proven to be non-destructive metrology tools for characterizing ultra-shallow junctions.展开更多
基金Projects(50975237,51005184) supported by the National Natural Science Foundation of China
文摘High-speed milling of titanium alloys is widely used in aviation and aerospace industries for its high efficiency and good quality.In order to optimize the machining parameters in high-speed milling TB6 titanium alloy,experiments of high-speed milling and fatigue were conducted to investigate the effect of parameters on 3D surface topography and fatigue life.Based on the fatigue fracture,the effect mechanism of surface topography on the fatigue crack initiation was proposed.The experiment results show that when the milling speed ranged from 100 m/min to 140 m/min,and the feed per tooth ranged from 0.02 mm/z to 0.06 mm/z,the obtained surface roughness were within the limit（0.8 μm）.Fatigue life decreased sharply with the increase of surface equivalent stress concentration factor.The average error of fatigue life between the established model and the experimental results was 6.25%.The fatigue cracks nucleated at the intersection edge of machined surface.
文摘Parts of complex surface are widely used now in many fields, and their detection has caused much concern. In China many manufactories still carry on the traditional way of manual detection, which requires highly skilled personnel and efficiency is low. Some large manufactories have imported auto-detecting equipments, which require CAD data on the parts, or just divide the surface into several approximate planes for automatic detection. Phased-array system is seldom used, and the cost is high. Besides, most of the systems have not considered the automatic sensitivity compensation of parts with varying thickness. To improve the detection quality and efficiency of nondestructive test (NDT) of parts of complex surface, this paper puts forward an integrated ultrasonic NDT system characterized by: (1) Use of ultrasonic measurement and reverse of curved surface to solve the CAD data problem; (2) Use of an automatic sensitivity compensation algorithm (based on the part’s modelling information obtained in surface reverse) to fit the variety of the thickness; (3) Use of template matching and pseudo-color imaging to improve the quality of detection results. The system features integration of low cost mature technologies, and is suitable for detection of various parts of different complex surfaces in medium-and-small enterprises. The test results showed that the system can automatically detect parts of complex surface successfully, and that the inspection result is good and reliable.
基金supported by the National Natural Science Foundation of China(Grant Nos. 61076090 and 60676058)
文摘Spectroscopic ellipsometry (SE), photocarrier radiometry (PCR) and photoluminescence (PL) techniques were employed to measure the ultra-shallow junction (USJ) wafers. These USJ wafers were prepared by As+ ion implantation at energies of 0.5-5 keV, at a dose of 1×1015 As+ /cm 2 and spike annealing. Experimentally the damaged layer of the as-implanted wafer and the recrystallization and activation of the post-annealed wafer were evaluated by SE in the spectral range from 0.27 to 20 m. The PCR amplitude decreased monotonically with the increasing implantation energy. The experimental results also showed that the PCR amplitudes of post-annealed USJ wafers were greatly enhanced, compared to the non-implanted and non-annealed substrate wafer. The PL measurements showed the enhanced PCR signals were attributed to the band-edge emissions of silicon. For explaining the PL enhancement, the electronic transport properties of USJ wafers were extracted via multi-wavelength PCR experiment and fitting. The fitted results showed the decreasing surface recombination velocity and the decreasing diffusion coefficient of the implanted layer contributed to the PCR signal enhancement with the decreasing implantation energy. SE, PCR and PL were proven to be non-destructive metrology tools for characterizing ultra-shallow junctions.
