The dumbbell-shaped metallic glass based composites of (Zr0.55Al0.1Ni0.05 Cu0.30)100-xTix (x=0, 2, 4, 6, 8) were prepared by copper mold casting method. Microstructure and fracture toughness of samples were studied by...
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The dumbbell-shaped metallic glass based composites of (Zr0.55Al0.1Ni0.05 Cu0.30)100-xTix (x=0, 2, 4, 6, 8) were prepared by copper mold casting method. Microstructure and fracture toughness of samples were studied by X-ray diffraction (XRD), universal testing machine and scanning electron microscope (SEM). The results indicate that metallic glass based composites can be fabricated by adjusting Ti addition. The structure of the alloys were composed of metallic glass and crystal when the Ti content was x=0, 2, 4 and the structure of the alloys were crystal when the Ti content was x=6, 8. The fracture toughness of composites which Ti content was x=0, 2, 4 were measured by three point bending method, and the KIC value were 10.529, 5.142 and 3.446 MPa·m1/2 respectively.
In order to realize the stable welding process in Pulsed MIG welding of Aluminum Alloy, the dynamical mathematical model between pulse parameters and arc length in Pulsed MIG welding was set up. When the pulse paramet...
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In order to realize the stable welding process in Pulsed MIG welding of Aluminum Alloy, the dynamical mathematical model between pulse parameters and arc length in Pulsed MIG welding was set up. When the pulse parameters changed, the response that the arc length was controlled and simulated by Matlab/Simulink software was studied. The simulated result shows the model can describe the dynamical change of arc length. For better and steady real-time control pulsed MIG welding process laid the foundation.
In order to control weld penetration of carbon steel more favorable, the process of double-electrode MIG welding and image segmentation algorithm based on MSRF model were studied. The welding pool was shot by passive ...
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In order to control weld penetration of carbon steel more favorable, the process of double-electrode MIG welding and image segmentation algorithm based on MSRF model were studied. The welding pool was shot by passive visual inspection system. The principles, visual collected system and image segmentation algorithm were introduced. The captured welding pool image was segmented and detected. Finally, the detected results used by Canny differential operators and this algorithm respectively were compacted. The result indicates that the algorithm based on MSRF model can detect the edge of welding pool which includes rich molten pool information. Also this algorithm runs less computational complexity, has higher convergence speed and avoids over-segmentation phenomena than differential operators. A new image segmentation algorithm was provided for controlling weld penetration of carbon steel by Double-Electrode MIG Welding.
A 3-D finite element model of two-stage thermoelectric generator based on low-temperature thermoelectric material bismuth-telluride and medium-temperature thermoelectric material skutterudites is established. Based on...
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B4C ceramics doped with various content of Si (0 to 2.03 at%) are prepared via hot pressing. The composition and microstructure of the ceramics are characterized by means of XRD and EPMA. Their electrical conductivity...
B4C ceramics doped with various content of Si (0 to 2.03 at%) are prepared via hot pressing. The composition and microstructure of the ceramics are characterized by means of XRD and EPMA. Their electrical conductivity and Seebeck coefficient of the samples are measured from room temperature up to 1500K. The electrical conductivity increases with temperature, and more rapidly after 1300K; the Seebeck coefficient of the ceramics also increases with temperature and rises to a value of about 320μVK−1. The value of the figure of merit of Si-doped B4C rises to about 4 × 10−4 K−1 at 1500K.
The momentum of strong backward flowing melt jet and the thermal action from transferred droplets are two dominating factors affecting the formation of humping bead in high speed gas metal arc welding （GMAW）. Approp...
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The momentum of strong backward flowing melt jet and the thermal action from transferred droplets are two dominating factors affecting the formation of humping bead in high speed gas metal arc welding （GMAW）. Appropriate describing the influ- ence of the distribution mode of droplet heat content in the weld pool is essential to understand the physical mechanism of humping bead formation. Based on the exper- imental results, four kinds of droplet heat content distribution modes are proposed and employed to calculate the transient evolution of the temperature field and weld pool during high speed GMAW process. Through making comparison of predicted and measured weld bead dimensions, a suitable and adaptive distribution mode of droplet heat content is found, i.e., droplet heat content is distributed in bottom layer of gouging region at the front of weld pool, and is averagely distributed in the whole layer at the rear of weld pool. The proposed mode is also validated by experimental observation of the weld pool images and measured by geometric dimensions of the weld bead.
WO3-based varistors doped with Y2O3 were prepared and the microstructure, nonlinear electrical properties, and dielectric properties were investigated. Breakdown voltages Eb of WO 3 doped with Y2O3 are lower than that...
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In present study LiMn2O4-xFx were prepared by the sol-gel method. X-ray diffraction (XRD) and scanning electron microscope (SEM ) were employed to detect the microstructure of the reaction products. It were found perf...
In present study LiMn2O4-xFx were prepared by the sol-gel method. X-ray diffraction (XRD) and scanning electron microscope (SEM ) were employed to detect the microstructure of the reaction products. It were found perfect crystal particles were obtained, and its' size were uniform in 1∼2 μ m. The specific capacity and cycleability were measured basing on battery program control test system. The results shown the substitution of F for O increased the specific capacity of the material at the cost of the cycleability due to more Mn3+ and less Mn4+ existed in the material. The exist of Mn3+ would reduce cycleability of cathode material due to the Jahn-Teller effect which were caused by the deformation of the crystal structure.
The operation characteristics of proton exchange membrane fuel cells with the channel width of 1mm and 2 mm under a medium-pressure are addressed, and the effect of temperature on the operation characteristic is inves...
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The operation characteristics of proton exchange membrane fuel cells with the channel width of 1mm and 2 mm under a medium-pressure are addressed, and the effect of temperature on the operation characteristic is investigated in detail. The results show that fuel cell with a 2 mm channel width can realize the long time operation in a closed-ended situation. The voltage of the 1mm width cell can drop from 0.7 V to 0.5 V in 3 min, while the 2 mm width cell can last for more than 53 min. Moreover, the temperature has a significant effect on the performance, the voltage of the 1 mm width cell can drop from 0.69 V to 0.5 V in less than 1.7 min. The resistance of the cell is increasing with the temperature, but the amplitude is smaller in high temperature.
Aluminum nitride whiskers were synthesized by nitridation of commercial aluminum powder at 1623K in a nitrogen atmosphere. The starting materials consisted of aluminum and carbon black. The carbon acted as a barrier b...
Aluminum nitride whiskers were synthesized by nitridation of commercial aluminum powder at 1623K in a nitrogen atmosphere. The starting materials consisted of aluminum and carbon black. The carbon acted as a barrier between aluminum powders during nitridation and was removed by heating in air at 923K. The whiskers were about 0.5-1μm in diameter and 10-20μm in length. The droplets at the whisker tips showed that the whiskers grew via a vapor-liquid-solid mechanism. The morphologies of the whiskers were studied by means of SEM and TEM. The formation of the whiskers depended on the processing conditions.
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