Papers by Author: Li Qiao

Abstract: In order to develop new Al alloy, the quasi-static and dynamic compression deformation behavior of an advanced Al-Mg alloy, which contained Zn and rare earth, were investigated. Deformed microstructures in the shear bands of this alloy were characterized by optical microscope. Results show that the compressive strengths increase with strain and strain rates being increased, and microstructures of deformed Al-Mg alloy along compression directions are sensitive to strain rates. The distorted deformation twins near the deformed band can be formed under low strain rate of 5.6×10^-3 s^-1, while multiple shear bands slipping can be induced by dynamic deformation under high strain rates from 1.9×10³ s^-1 to 5×10³ s^-1. Therefore, compressive strength and fracture strain of dynamic deformation are higher than that of the quasi-static deformation, which is attributed to the strain hardening and grain refining in the multiple shear bands.

Abstract: By means of mechanical properties test and structure observation， the relationship among electric field strength, polar molecule type, content on the Ni/TiO₂ group electrorheological fluid properties have been analyzed. It is found that with increasing electric field strength，the properties of electrorheological fluid increased for same composition ER fluid. Different type polar molecules have distinct effect. For same particle，with increasing polar molecule content，the property is increased, but there is a critical value . Polar molecule make particles chain of electrorheological fluid become strong，coarse and interweaved each other.

Abstract: By means of mechanical properties test and microstructure observation,the relationship between mechanical properties ,microstructure graph of core-shell Ni/TiO₂ group particles concentration of EMR and different electric field, magnetic field or electric-magnetic field have been researched. It is found that with increasing of particles concentration, the properties are increased. But there is a critical range value, too high or too low particles concentrations are harmful to properties and microstructure. The best particles concentration of Ni/TiO₂ particles is about 30%. In the same field with increasing concentration, particles chain of electrorheological fluid under certain electric field become more strong,brawnier and interweaved each other.

Abstract: By means of structure analysis, mechanical properties test and microstructure observation，structure of Ni and Ni/TiO₂ group particles have been obtained, the relationship among partic_{Subscript textSubscript text}le diameter，electric field strength and shear ratio of the properties of Ni/TiO₂ group core-shell particles ER fluid have been researched. It has been found that with increasing particle diameter，the shear stress of ER fluid decreased, and with increasing shear ratio，the shear stress of ER fluid increased for same diameter particle and composition ER fluid. At same time, the smaller of particle diameter, the higher of ER properties such as shear stress, but there is a critical value for shear ratio, when shear ratio is larger than critical value, the properties of ER is nearly a value for same composition ER fluid. Particles chain of ER fluid under certain electric field is different with diversity Ni group Particles.

Abstract: By way of mechanical properties test and microstructure observation，the effect of Urea on TiO₂ particles has been researched，it has showed that ER fluid activity of the particles were closely associated with urea content. When the mass ratio of Urea/Ti is 30%, The property of TiO₂/Urea particles ER fluid is the best .The microstructure observation of the ER fluids under DC electric field showed that the particles aggregated to form thicker and dense column structure when the mass ratio of Urea/Ti is 30%, while the column structure were broken down when excessive urea/Ti (>30%) was been added.

Abstract: By means of mechanical properties test，the relationship among shear ratio, concentration and electric field, magnetic field ,electromagnetic field on the Ni/TiO2 group electrorheological fluid properties have been analyzed. It is found that with increasing shear ratio，the property of electrorheological fluid increased for same composition ER, but there is a critical value. With increasing concentration，the property of electrorheological fluid increased for same shear ratio. Coupling electromagnetic field makes the properties improve.

Abstract: By means of mechanical properties test and microstructure graph observation，the relationship of heat treatment temperature of core-shell Ni/TiO2 group particles with mechanical properties under different electric field has been researched .It is found that the FT-IR，XRD morphology of heat treatment at350°C is different from the one at100°C，the shear stress of same composition ER decreased with heat treatment temperature increasing. But the leakage current density of ER shows contrary result. That is because the leakage current density of ER decreased with the increasing heat treatment temperature.

Abstract: By means of mechanical properties test and microstructure graph observation，the effect of core-shell Ni/TiO2 particles size, concentration on the properties and morphology of electrorheological fluid was emphatically studied, It is found that with concentration increasing the properties of electrorheological fluid can be improved, but there is a critical value, Urea content of Ni/TiO2 particles is 30%, in the same field with increasing concentration, particles chain of electrorheological fluid become strong，coarse and interweaved each other. The smaller of particle size, the higher of shear strength of electrorheological fluid.