In order to improve the wear resistance of titanium alloys,the potential of the plasma nitriding process with a cathode assiting discharge setup was examined.Ti6Al4V alloy was nitrided by the cathode assiting discharg...In order to improve the wear resistance of titanium alloys,the potential of the plasma nitriding process with a cathode assiting discharge setup was examined.Ti6Al4V alloy was nitrided by the cathode assiting discharge nitriding(CAN) and conventional DC plasma nitriding(CPN) methods,respectively.The micro-topography,phase composition and cross-sectional microhardness distribution of two nitriding layers were studied comparatively.The sliding wear resistance of the nitriding layers was examined by a ball-on-disk test against Si3N4 balls.The results indicated that the surface roughness Ra of the CAN layer was about 1 order less than that of the CPN layer.In addition,the CAN surfaces possessed significantly greater wear resistance than the CPN layer at higher loads,and increased the wear resistance of Ti6Al4V alloy by about 2 orders due to the higher loading bearing ability,higher rate of TiN phase,greater surface microhardness and bigger microhardness improving depth.This is because the double glow discharge effect in CAN strengthened the density of the active nitrogen atoms and the nitriding efficiency.Moreover,the ion bombardment effect on the surface of the nitriding titanium alloy was reduced obviously.展开更多
A novel arc-shaped piezoelectric generator based on flexible PVDF thin film is presented and systemically studied.With a periodical external force,the generator can produce peak voltage of 45.6 V and peak power of 30....A novel arc-shaped piezoelectric generator based on flexible PVDF thin film is presented and systemically studied.With a periodical external force,the generator can produce peak voltage of 45.6 V and peak power of 30.7μW.The maximum power density reaches 38.4μW/cm3with a 4 cm×2 cm×100μm device,at the optimum load resistance of 33.33 MOhm.The influence of frequency,size dimension and load resistance are investigated through experimental measurements.With this high output arc-shaped generator,capacitors can be effectively charged and three commercial LEDs have been directly lighted without any energy storage unit.展开更多
There has not been an effective method to measure the resistivity of small-size sample of mineral and solid insulating material until now.According to the Chinese National Standard(GB/T1410-2006) and features of digit...There has not been an effective method to measure the resistivity of small-size sample of mineral and solid insulating material until now.According to the Chinese National Standard(GB/T1410-2006) and features of digital high resistance meter,a small electrode experimental installation was developed;it can work with current high resistance meter;the sample decreases to 18 mm from standard size 100 mm in diameter and reduces by 30.86 times in area.A three-electrode system is supported and precisely positioned by two insulating bases whose diameter is 60 mm and height is 20 mm,which ensures accuracy of device structure and reliability of measuring results.The key technological parameters are as follows:diameter of high voltage electrode is 18mm;diameter of measuring electrode is 14.6 mm;internal diameter and external diameter of guard electrode are 16 and 18 mm,respectively;the gap between guard electrode and measuring electrode is set at 0.6 mm.These parameters are adequate for the measurement of flat specimen of mineral and solid insulating material whose diameter is 18 mm.According to the confirmatory experiment on the volume resistivity and surface resistivity,the measuring results are almost the same,using a small electrode experimental installation and a standard electrode.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 51171154,51101127)
文摘In order to improve the wear resistance of titanium alloys,the potential of the plasma nitriding process with a cathode assiting discharge setup was examined.Ti6Al4V alloy was nitrided by the cathode assiting discharge nitriding(CAN) and conventional DC plasma nitriding(CPN) methods,respectively.The micro-topography,phase composition and cross-sectional microhardness distribution of two nitriding layers were studied comparatively.The sliding wear resistance of the nitriding layers was examined by a ball-on-disk test against Si3N4 balls.The results indicated that the surface roughness Ra of the CAN layer was about 1 order less than that of the CPN layer.In addition,the CAN surfaces possessed significantly greater wear resistance than the CPN layer at higher loads,and increased the wear resistance of Ti6Al4V alloy by about 2 orders due to the higher loading bearing ability,higher rate of TiN phase,greater surface microhardness and bigger microhardness improving depth.This is because the double glow discharge effect in CAN strengthened the density of the active nitrogen atoms and the nitriding efficiency.Moreover,the ion bombardment effect on the surface of the nitriding titanium alloy was reduced obviously.
基金supported by the National Natural Science Foundation of China(Grant Nos.61176103,91023045)the National Hi-Tech Research and Development Program("863" Project)(Grant No.2013AA041102)the National Ph.D.Foundation Project(Grant No.20110001110103)
文摘A novel arc-shaped piezoelectric generator based on flexible PVDF thin film is presented and systemically studied.With a periodical external force,the generator can produce peak voltage of 45.6 V and peak power of 30.7μW.The maximum power density reaches 38.4μW/cm3with a 4 cm×2 cm×100μm device,at the optimum load resistance of 33.33 MOhm.The influence of frequency,size dimension and load resistance are investigated through experimental measurements.With this high output arc-shaped generator,capacitors can be effectively charged and three commercial LEDs have been directly lighted without any energy storage unit.
基金supported by the National Natural Science Foundation of China (Grant No. 50974025)the National Key Technologies R & D Program of China (Grant No. 2004BA810B02)+2 种基金the Applied Foundation of Basic Research in Sichuan Province (Grant No. 07JY029-029)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20095122110015)the Scientific Research Foundation of the Education Ministry for Returned Chinese Scholars, China (Grant No. 2010-32)
文摘There has not been an effective method to measure the resistivity of small-size sample of mineral and solid insulating material until now.According to the Chinese National Standard(GB/T1410-2006) and features of digital high resistance meter,a small electrode experimental installation was developed;it can work with current high resistance meter;the sample decreases to 18 mm from standard size 100 mm in diameter and reduces by 30.86 times in area.A three-electrode system is supported and precisely positioned by two insulating bases whose diameter is 60 mm and height is 20 mm,which ensures accuracy of device structure and reliability of measuring results.The key technological parameters are as follows:diameter of high voltage electrode is 18mm;diameter of measuring electrode is 14.6 mm;internal diameter and external diameter of guard electrode are 16 and 18 mm,respectively;the gap between guard electrode and measuring electrode is set at 0.6 mm.These parameters are adequate for the measurement of flat specimen of mineral and solid insulating material whose diameter is 18 mm.According to the confirmatory experiment on the volume resistivity and surface resistivity,the measuring results are almost the same,using a small electrode experimental installation and a standard electrode.
