Significant impact of the current collection material and method on the performance of Ba0.5Sr0.5Co0.8Fe0.2O3−δ electrodes in solid oxide fuel cells

The effects of the current collection material and method on the performance of SOFCs with Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCF) cathodes are investigated. Ag paste and LaCoO₃ (LC) oxide are studied as current collection materials, and five different current collecting techniques are attempted. Cell performances are evaluated using a current-voltage test and electrochemical impedance spectra (EIS) based on two types of anode-supported fuel cells, i.e., NiO + SDC|SDC|BSCF and NiO + YSZ|YSZ|SDC|BSCF. The cell with diluted Ag paste as the current collector exhibits the highest peak power density, nearly 16 times that of a similar cell without current collector. The electrochemical characteristics of the BSCF cathode with different current collectors are further determined by EIS at 600 °C using symmetrical cells. The cell with diluted Ag paste as the current collector displays the lowest ohmic resistance (1.4 Ω cm²) and polarization resistance (0.1 Ω cm²). Meanwhile, the surface conductivities of various current collectors are measured by a four-probe DC conductivity technique. The surface conductivity of diluted Ag paste is 2-3 orders of magnitude higher than that of LC or BSCF. The outstanding surface conductivity of silver may reduce the contact resistance at the current collector/electrode interface and, thus, contributes to better electrode performance.     

热电偶测温原理中的基本定律

阐述均质导体、中间导体和中间温度3定律的基本理论和其应用。     

The effect of rear surface polishing to the performance of thin crystalline silicon solar cells

As the thickness of crystalline silicon solar cells decreases, light loss cannot be avoided due to the absorption limit in long wavelength light. Internal rear side reflection can be enhanced by polishing the rear surface. The rear polishing processes are performed before the texturing and before and after doping the emitter layer to optimize the solar cell fabrication process sequences. All cells made by rear surface polishing showed improved light trapping in long wavelength region (900-1100 nm) compared to that in the conventional cells. However, silicon solar cells fabricated by rear polishing before and after doping have similar (35.5 mA/cm²) or lower (35.26 mA/cm²) short circuit current density compared to the cells produced by the conventional process (35.59 mA/cm²) due to pore damage to the anti-reflection layer and the surface of the emitter layer during rear polishing. This surface damage was effectively prevented adapting the rear surface polishing before the front surface texturing, which led to increasing the current density from 35.59 to 36.29 mA/cm².     

Ti对Nb-20Si-5Al超高温合金性能的影响

采用放电等离子烧结法(SPS)制备了Nb-20Si-5Al-xTi(x=0,18,20,22,摩尔分数)超高温合金,研究了Ti加入量对Nb-20Si-5Al合金的室温断裂韧度和高温抗氧化性的影响。结果表明,随着Ti加入量的增加,超高温合金的相组成由Nbss、Nb₅Si₃和Al3Nb相转变成为Nbss、(Nb,Ti)5Si3和Ti相。Ti能明显改善Nb-20Si-5Al超高温合金的断裂韧度和高温抗氧化性能,随着Ti加入量的增加均先提高然后降低,在Ti加入量为20%时,合金断裂韧度最大,为7.41 MPa·m^1/2,相比未加Ti时提高了约56.9%,其高温氧化速率最低,为0.72×10^-4g²/(cm⁴·h)。添加Ti元素后,其氧化产物中出现Ti₂Nb₁₀O₂₉、TiNb₂O₇、TiO₂等,可以提高其氧化膜的致密性,从而提高高温抗氧化性能。     

半连续铸造铝合金表面缺陷的形成机理及影响因素

介绍了半连续铸造铝合金锭坯冷隔、皮下偏析层、表面偏析瘤、拉痕等表面缺陷的特点和形成机制。分析了在半连续铸造铝合金锭坯过程中结晶器结构、铸造工艺参数对这些表面缺陷的影响及作用机理。在此基础上总结了提高铸锭表面品质的技术发展和工艺优化方向。     

3D打印在新能源汽车电机壳体预防粘模上的应用

针对新能源汽车电机壳体压铸件产生粘模缺陷的问题,从模具结构设计、3D打印嵌件平衡模具温度,防止高温铝液破坏模具表面致密层等方面,在生产过程中对新能源电机壳体压铸件粘模缺陷进行改善,提出了应用3D打印嵌件的解决方案。     

基于BP-PID的选择性激光烧结温度控制系统设计

为消除纯滞后系统的超调、改善温度因素对制件质量和强度的影响,设计一种基于BP-PID算法的选择性激光烧结温度控制系统.该系统采用层次化架构和模块化的设计方案,以STM32控制器作为主控模块,并利用BP神经网络改进传统比例-积分-微分(PID)算法,提高了控制系统的稳定性且效果显著.通过MATLAB进行仿真模拟,与传统PID控制进行对比并进行实验.结果表明:BP-PID算法能迅速整定最优参数,且超调量小,达到稳态所用时间更短;在设定预热温度为90℃且采用BP-PID算法控制时,系统稳态误差在±1℃之内,超调量小于3％.     

电力变压器杂散损耗预估

利用MagNet软件,对铁心夹件、油箱和电屏蔽采用表面阻抗边界条件,计算了铁心夹件、拉板、油箱及低压引线升高座等结构件损耗,分析了夹件宽度、油箱磁分路和引线升高座屏蔽对损耗的影响。     

Evaluation of Adhesion Improvement of a GFRP Treated with Atmospheric Plasma Torch

The applications (and repair) of glass fiber reinforced epoxy composites are increasing in different industries (wind turbines, boats, chassis of buses, etc.) due to specific strength and low cost. Their major disadvantage is the difficulty to shape complex components. This problem can be solved manufacturing different parts, being adhesively bonded afterwards. This work studies the effect of atmospheric pressure plasma torch compared to grit-blasting to improve adhesion. After surface treating different parts, the changes of wettability and surface energy were measured. Treated samples were bonded with polyurethane and epoxy adhesives, and the quality of the bond was evaluated using pull-off adhesion tests and fracture strength test under cleavage loads. Obtained results allow to select the most adequate treatment in terms of mechanical requirements.     

Study on fibre laser spot welding of TRIP980 steel

A 980 MPa transformation induced plasticity (TRIP) steel was fibre laser spot welded by different Argon (Ar) shielding conditions, laser power (1000 up to 2500 W) and defocusing distances (?8 up to +8 mm). The surface appearance, cross-section macrostructure, microstructure, hardness, tensile shear properties and fatigue properties of laser spot welds were evaluated. The results showed that the welds with Ar shielding had larger weld appearance and bonding sizes, better tensile shear properties compared with the welds without Ar shielding. With the increase in laser power, the laser welding mode changed from conduction to keyhole, which improved the bonding size and mechanical properties. The bonding size and mechanical properties increased in the order of defocusing distances of +8, ?8, +4, ?4 and 0 mm. During the fatigue tests of laser spot weld, the fusion zone pullout and sheet transverse fracture failure modes were observed.