Song X.,Harbin Institute of Technology |
Cao J.,Harbin Institute of Technology |
Li Z.,Beijing Institute of Controlling Engineering |
Zhang Z.,Beijing Institute of Controlling Engineering |
Feng J.,Harbin Institute of Technology
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2013
Ti53311S high-temperature titanium alloy was brazed using TiZrNiCu filler metal. The interfacial microstructure was characterized by SEM, EDS and Micro-focus XRD. Effects of the brazing temperature on the interfacial microstructure and mechanical properties of the joints were investigated. The results show that the typical interfacial microstructure is Ti53311S/α+β/(Ti, Zr)2(Cu, Ni) compounds/α+β/Ti53311S. The content of brittle (Ti, Zr)2(Cu, Ni) compounds decreases with the temperature increasing and the lamellar α+β microstructure is formed when the brazing temperature exceeds the transformation temperature of α+β→β. Tensile strength of joints increases gradually at first and then tends to be stable with the increase of brazing temperature. The highest tensile strength of 912.8 MPa is obtained when the specimens are brazed at 1010°C for 10 min. Fracture analysis indicates that the joints fracture at brazing seam showing lots of cleavage planes on the fracture surfaces. © 2013, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved.
Wei F.,Beijing Institute of Controlling Engineering |
He Y.,China Academy of Space Technology |
Geng J.,Beijing Institute of Controlling Engineering
Zhongguo Kongjian Kexue Jishu/Chinese Space Science and Technology | Year: 2016
The constrictor is a key part of arcjet thrusters, which has a significant effect on the performance and efficiency of the arcjet thruster. A modeling study was performed to investigate the plasma flow through the constrictor of medium power arcjet thrusters based on the local thermal equilibrium(LTE) assumption. The effects of the current, inlet pressure, constrictor dimensions and different propellants on the plasma flow characteristics, including the nonuniform flow characteristics, within the arcjet constrictor were studied. And the effects of the current, inlet pressure and constrictor dimensions on the performance and efficiency were further presented. The numerical results show that the hot arc region radius and length increase with the increase of the current; with the increase of the inlet pressure, the radius of hot arc region decreases but length increases; with the decrease of the constrictor radius, the hot arc region radius decreases while length increases; the hot arc region length increases and radius shows no significant changes with the increase of the constrictor length; and the hot arc region with hydrogen as the propellant is apparently smaller than those with nitrogen and argon as the propellant. It is also found that a small amount of the gas passes through the hot arc region where the gas is ionized, and most of the gas flows through the low temperature region near the wall. The Joule heating within the constrictor approximately accounts for 60%-80% of the total Joule heating within the arcjet thruster, mainly affected by the constrictor length. © 2016, Editorial Office of Journal of Chinese Space Science and Technology. All right reserved.
Su S.,Changchun University of Science and Technology |
Su S.,Key Laboratory of Optoelectronic Measuring Controlling and Optical Information Transmitting Technology |
Xu X.,Changchun University of Science and Technology |
Xu X.,Key Laboratory of Optoelectronic Measuring Controlling and Optical Information Transmitting Technology |
And 6 more authors.
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2012
According to the whole machine experiment needs of spin scanning earth sensor of Fengyun-2 satellite, a new portable binocular earth sensor was proposed. The composition, general structure and working principle of the simulator system were introduced, and the key technology was discussed. The calculation process of the earth chord width and radiant brightness, and the design process of thermal earth and optical modulator were described as well. The test result indicates that the temperature control precision reaches 0.10°C and the modulation frequency control precision reaches 0.1 Hz, the output signal of the earth simulator that sensor detected is basically anastomosis of its outer space working state waveform.