直流高压高阻箱是主要用于检定、校准绝缘电阻表和高阻计的计量标准器。提出电阻分压电路(RVD c ircu it)测量直流高压高阻箱的方法,同时给出测量原理图和计量标准装置的构成,并对分压组合电路测量直流高压高阻箱示值误差的测量不确定...直流高压高阻箱是主要用于检定、校准绝缘电阻表和高阻计的计量标准器。提出电阻分压电路(RVD c ircu it)测量直流高压高阻箱的方法,同时给出测量原理图和计量标准装置的构成,并对分压组合电路测量直流高压高阻箱示值误差的测量不确定度进行了评定。展开更多
Piezoresistive effect of carbon nanotube films was investigated by a three-point bending test. Carbon nanotubes were synthesized by hot filament chemical vapor deposition. The experimental results showed that the carb...Piezoresistive effect of carbon nanotube films was investigated by a three-point bending test. Carbon nanotubes were synthesized by hot filament chemical vapor deposition. The experimental results showed that the carbon nanotubes have a striking piezoresistive effect. The relative resistance was changed from 0 to 10.5×10-2 and 3.25×10-2 for doped and undoped films respectively at room temperature when the microstrain under stress from 0 to 500. The gauge factors for doped and undoped carbon nanotube films under 500 microstrain were about 220 and 67 at room temperature, respectively, exceeding that of polycrystalline silicon （30） at 35℃. The origin of the resistance changes in the films may be attributed to a strain-induced change in the band gap for the doped tubes and the defects for the undoped tubes.展开更多
The piezoresistive behavior of carbon black (CB) filled poly(methyl vinyl siloxane) (PMVS) vulcanites under uniaxial compression was studied.At filler weight frac- tions φ slightly above the percolation threshold φc...The piezoresistive behavior of carbon black (CB) filled poly(methyl vinyl siloxane) (PMVS) vulcanites under uniaxial compression was studied.At filler weight frac- tions φ slightly above the percolation threshold φc,resistance first increased with pressure and then turned to decrease at a critical compressive stress,exhibiting a positive pressure co- efficient of resistance (PPCR) and a negative pressure coeffi- cient of resistance (NPCR) effects ,respectively.The NPCR effect became much more pronounced at φ>>φc,while com- pressive cycles facilitated the occurrence of the weak PPCR effect during compression.The PPCR-NPCR transition was a process related to true stress.It is believed that the changes of microstructure in the percolating network,i.e. the breakdown and the reformation of infinite conducting clusters,under pressure would be responsible for the uniaxial piezoresis- tance and the plastic deformation of the filled vulcanites.展开更多
基金National Natural Science Foundation of China (60376032)
文摘Piezoresistive effect of carbon nanotube films was investigated by a three-point bending test. Carbon nanotubes were synthesized by hot filament chemical vapor deposition. The experimental results showed that the carbon nanotubes have a striking piezoresistive effect. The relative resistance was changed from 0 to 10.5×10-2 and 3.25×10-2 for doped and undoped films respectively at room temperature when the microstrain under stress from 0 to 500. The gauge factors for doped and undoped carbon nanotube films under 500 microstrain were about 220 and 67 at room temperature, respectively, exceeding that of polycrystalline silicon （30） at 35℃. The origin of the resistance changes in the films may be attributed to a strain-induced change in the band gap for the doped tubes and the defects for the undoped tubes.
基金This work was supported by the Key Program of the National Natural Science Foundation of China(Grant No.50133020)the National Science Foundation for Distinguished Young Scholars(Grant No.50125312).
文摘The piezoresistive behavior of carbon black (CB) filled poly(methyl vinyl siloxane) (PMVS) vulcanites under uniaxial compression was studied.At filler weight frac- tions φ slightly above the percolation threshold φc,resistance first increased with pressure and then turned to decrease at a critical compressive stress,exhibiting a positive pressure co- efficient of resistance (PPCR) and a negative pressure coeffi- cient of resistance (NPCR) effects ,respectively.The NPCR effect became much more pronounced at φ>>φc,while com- pressive cycles facilitated the occurrence of the weak PPCR effect during compression.The PPCR-NPCR transition was a process related to true stress.It is believed that the changes of microstructure in the percolating network,i.e. the breakdown and the reformation of infinite conducting clusters,under pressure would be responsible for the uniaxial piezoresis- tance and the plastic deformation of the filled vulcanites.
