使用模具并采用磁控溅射法在铁电陶瓷PZT基体上沉积具有条形分布结构的Ni Ti SMA薄膜。显微组织结构观察发现,以条形分布结构方式沉积的Ni Ti SMA薄膜晶化处理后具有等轴晶结构。比较所制备PZT/Ni-Ti SMA薄膜复合材料与纯PZT的介电常数...使用模具并采用磁控溅射法在铁电陶瓷PZT基体上沉积具有条形分布结构的Ni Ti SMA薄膜。显微组织结构观察发现,以条形分布结构方式沉积的Ni Ti SMA薄膜晶化处理后具有等轴晶结构。比较所制备PZT/Ni-Ti SMA薄膜复合材料与纯PZT的介电常数及介电损耗发现,两者的介电损耗水平接近;复合材料的介电常数比纯PZT的提高约18%。Ni Ti SMA的沉积使基体中靠近薄膜区域的Zr/Ti物质的量比恰好落在准同型相界区内,致使所制备复合材料的介电性能优于纯PZT。展开更多
Over the years, there has been increased research interest in the application of Nitinol as an actuator, due to its shape memory behaviour, simplicity, high power-to-weight ratio, compactness, and extreme high fatigue...Over the years, there has been increased research interest in the application of Nitinol as an actuator, due to its shape memory behaviour, simplicity, high power-to-weight ratio, compactness, and extreme high fatigue resistance to cyclic motion, and noiseless operation. Nitinol has found application in tactile displays which reproduce tactile parameters such as texture and shape, depending on the application. This paper presents the effects of thermal interference between adjacent Nitinol spring actuators in a tactile display. The tactile display is made of a 3 by 3 pin array whose spatial resolution was varied from 4 mm to 6 mm in steps of 1 mm while a current of 1.5 A was used to actuate 8 of the springs, and the centre spring was left unactivated to observe the thermal effects on it due to the heat gradient formed. A Finite Element (FE) model was developed using COMSOL Multiphysics and the results were further verified through experimentation. In both cases, there was visible thermal interference between actuators. The increase in spatial resolution saw a decrease in thermal interference by 12.7%. Using a fan to introduce forced convection, reduced the thermal interference in the simulation by 20% and during experimentation by 11%. The results of this research indicate a spatial resolution of 6 mm reduced the thermal inference to a negligible rate. However, thermal interference could not be eliminated with these two methods.展开更多
A macroscopic based multi-mechanism constitutive model is constructed in the framework of irreversible thermodynamics to describe the degeneration of shape memory effect occurring in the thermo-mechanical cyclic defor...A macroscopic based multi-mechanism constitutive model is constructed in the framework of irreversible thermodynamics to describe the degeneration of shape memory effect occurring in the thermo-mechanical cyclic deformation of NiTi shape memory alloys (SMAs). Three phases, austenite A, twinned martensite and detwinned martensite , as well as the phase transitions occurring between each pair of phases (, , , , and are considered in the proposed model. Meanwhile, two kinds of inelastic deformation mechanisms, martensite transformation-induced plasticity and reorientation-induced plasticity, are used to explain the degeneration of shape memory effects of NiTi SMAs. The evolution equations of internal variables are proposed by attributing the degeneration of shape memory effect to the interaction between the three phases (A, , and and plastic deformation. Finally, the capability of the proposed model is verified by comparing the predictions with the experimental results of NiTi SMAs. It is shown that the degeneration of shape memory effect and its dependence on the loading level can be reasonably described by the proposed model.展开更多
Thermal explosion method was used to prepare porous NiTi shape memory alloy. The process of thermal explosion was investigated. The effect of process parameters on thermal explosion reaction and properties of products...Thermal explosion method was used to prepare porous NiTi shape memory alloy. The process of thermal explosion was investigated. The effect of process parameters on thermal explosion reaction and properties of products was analyzed. The results showed heating rate, green density, particle size of initial powder strongly affected combustion temperature, porosity and compressive strength of final products. The mechanism of thermal explosion and the microstructure of reacted products were studied by XRD and SEM photographs. The results showed the final products mainly comprised of NiTi, Ti2Ni and TiNi3 phases and their strength decreased with the increase of porosity.展开更多
文摘使用模具并采用磁控溅射法在铁电陶瓷PZT基体上沉积具有条形分布结构的Ni Ti SMA薄膜。显微组织结构观察发现,以条形分布结构方式沉积的Ni Ti SMA薄膜晶化处理后具有等轴晶结构。比较所制备PZT/Ni-Ti SMA薄膜复合材料与纯PZT的介电常数及介电损耗发现,两者的介电损耗水平接近;复合材料的介电常数比纯PZT的提高约18%。Ni Ti SMA的沉积使基体中靠近薄膜区域的Zr/Ti物质的量比恰好落在准同型相界区内,致使所制备复合材料的介电性能优于纯PZT。
文摘Over the years, there has been increased research interest in the application of Nitinol as an actuator, due to its shape memory behaviour, simplicity, high power-to-weight ratio, compactness, and extreme high fatigue resistance to cyclic motion, and noiseless operation. Nitinol has found application in tactile displays which reproduce tactile parameters such as texture and shape, depending on the application. This paper presents the effects of thermal interference between adjacent Nitinol spring actuators in a tactile display. The tactile display is made of a 3 by 3 pin array whose spatial resolution was varied from 4 mm to 6 mm in steps of 1 mm while a current of 1.5 A was used to actuate 8 of the springs, and the centre spring was left unactivated to observe the thermal effects on it due to the heat gradient formed. A Finite Element (FE) model was developed using COMSOL Multiphysics and the results were further verified through experimentation. In both cases, there was visible thermal interference between actuators. The increase in spatial resolution saw a decrease in thermal interference by 12.7%. Using a fan to introduce forced convection, reduced the thermal interference in the simulation by 20% and during experimentation by 11%. The results of this research indicate a spatial resolution of 6 mm reduced the thermal inference to a negligible rate. However, thermal interference could not be eliminated with these two methods.
基金Financial supports by the National Natural Science Foundation of China (Grant 11532010)the project for Sichuan Provincial Youth Science and Technology Innovation Team, China (Grant 2013TD0004)
文摘A macroscopic based multi-mechanism constitutive model is constructed in the framework of irreversible thermodynamics to describe the degeneration of shape memory effect occurring in the thermo-mechanical cyclic deformation of NiTi shape memory alloys (SMAs). Three phases, austenite A, twinned martensite and detwinned martensite , as well as the phase transitions occurring between each pair of phases (, , , , and are considered in the proposed model. Meanwhile, two kinds of inelastic deformation mechanisms, martensite transformation-induced plasticity and reorientation-induced plasticity, are used to explain the degeneration of shape memory effects of NiTi SMAs. The evolution equations of internal variables are proposed by attributing the degeneration of shape memory effect to the interaction between the three phases (A, , and and plastic deformation. Finally, the capability of the proposed model is verified by comparing the predictions with the experimental results of NiTi SMAs. It is shown that the degeneration of shape memory effect and its dependence on the loading level can be reasonably described by the proposed model.
文摘Thermal explosion method was used to prepare porous NiTi shape memory alloy. The process of thermal explosion was investigated. The effect of process parameters on thermal explosion reaction and properties of products was analyzed. The results showed heating rate, green density, particle size of initial powder strongly affected combustion temperature, porosity and compressive strength of final products. The mechanism of thermal explosion and the microstructure of reacted products were studied by XRD and SEM photographs. The results showed the final products mainly comprised of NiTi, Ti2Ni and TiNi3 phases and their strength decreased with the increase of porosity.
