The morphologies of tunnel tips in different stages for aluminum foils during DC etching in 1.5 mol/L HC1 solution at 90℃ were observed by field emission scanning electron microscopy （FE-SEM）. A novel model was pro...The morphologies of tunnel tips in different stages for aluminum foils during DC etching in 1.5 mol/L HC1 solution at 90℃ were observed by field emission scanning electron microscopy （FE-SEM）. A novel model was proposed to describe the morphological evolution of tunnel tips throughout the growth processes. In the pit nucleation stage, the pits vary from the hemispherical to half-cubic shapes due to the activation of pit tips from the center to the edge. During the tunnel growth stage, the pits dissolve toward the depth direction and develop into the tunnels, and their tips remain flat. In the tip passivation stage, as the passivation of tunnel tips speeds up from the edge to the center＇s the tunnel tips change from flat shapes to three-dimensional protrusions. The mechanism may be attributed to the order of activation or passivation on the tunnel tips changed in different stages.展开更多
The morphology of etched aluminum foil was observed using scanning electron microscopy, which led to the establishment of a cylindrical model and two merged models, considering the fixed weight loss of etching. The ma...The morphology of etched aluminum foil was observed using scanning electron microscopy, which led to the establishment of a cylindrical model and two merged models, considering the fixed weight loss of etching. The maximum of specific capacitance and the cor- responding optimum values for tunnel sizes at various anodization voltages were predicted. The increased size distribution and taper of tun- nels were demonstrated to decrease the specific capacitance, whereas the addition of polymeric additive into the ttmnel widening solution was demonstrated to increase the capacitance. The formation of merged tunnels on the etched aluminum surface, irrespective of the presence of row-merged tunnels or cluster-merged tunnels, resulted in a dramatic decrease in the specific capacitance. It is concluded that, enhancing the uniformity of turmel size and distribution and avoiding the formation of merged tunnels are the effective approach to achieving the higher capacitance for the tunnel etched and formed aluminum foil.展开更多
在开关电源系统中,电解电容相比较其他元件最易失效,寿命最短。为避免因电容失效造成损失,需要提前预知电解电容工作状态以便及时更换。由于电解电容的电容量C和等效串联电阻ESR(equivalent series resistance)的值可以反映出电解电容...在开关电源系统中,电解电容相比较其他元件最易失效,寿命最短。为避免因电容失效造成损失,需要提前预知电解电容工作状态以便及时更换。由于电解电容的电容量C和等效串联电阻ESR(equivalent series resistance)的值可以反映出电解电容性能的衰退程度,因此对电容该参数的在线监测十分重要。本文提出了一种AC/DC DCM反激变换器输出电解电容C和ESR的在线监测方案。通过分析输出电压纹波,推导出C和ESR的计算模型,并据此进行了监测系统设计。最后进行了仿真验证。仿真结果和数据验证了理论的有效性。展开更多
基金the financial support by the Guangxi Hezhou Guidong Electronics Technology Co.Ltd.the Research Project of Guangxi Zhuang Autonomous Region(Nos.1346011-7 and 1298019-11)
文摘The morphologies of tunnel tips in different stages for aluminum foils during DC etching in 1.5 mol/L HC1 solution at 90℃ were observed by field emission scanning electron microscopy （FE-SEM）. A novel model was proposed to describe the morphological evolution of tunnel tips throughout the growth processes. In the pit nucleation stage, the pits vary from the hemispherical to half-cubic shapes due to the activation of pit tips from the center to the edge. During the tunnel growth stage, the pits dissolve toward the depth direction and develop into the tunnels, and their tips remain flat. In the tip passivation stage, as the passivation of tunnel tips speeds up from the edge to the center＇s the tunnel tips change from flat shapes to three-dimensional protrusions. The mechanism may be attributed to the order of activation or passivation on the tunnel tips changed in different stages.
基金financially supported by the Research Project of Guangxi Zhuang Autonomous Region,China(Nos.1346011-7 and 1298019-11)the financial support from the Guangxi Hezhou Guidong Electronics Technology Co.,Ltd
文摘The morphology of etched aluminum foil was observed using scanning electron microscopy, which led to the establishment of a cylindrical model and two merged models, considering the fixed weight loss of etching. The maximum of specific capacitance and the cor- responding optimum values for tunnel sizes at various anodization voltages were predicted. The increased size distribution and taper of tun- nels were demonstrated to decrease the specific capacitance, whereas the addition of polymeric additive into the ttmnel widening solution was demonstrated to increase the capacitance. The formation of merged tunnels on the etched aluminum surface, irrespective of the presence of row-merged tunnels or cluster-merged tunnels, resulted in a dramatic decrease in the specific capacitance. It is concluded that, enhancing the uniformity of turmel size and distribution and avoiding the formation of merged tunnels are the effective approach to achieving the higher capacitance for the tunnel etched and formed aluminum foil.
文摘在开关电源系统中,电解电容相比较其他元件最易失效,寿命最短。为避免因电容失效造成损失,需要提前预知电解电容工作状态以便及时更换。由于电解电容的电容量C和等效串联电阻ESR(equivalent series resistance)的值可以反映出电解电容性能的衰退程度,因此对电容该参数的在线监测十分重要。本文提出了一种AC/DC DCM反激变换器输出电解电容C和ESR的在线监测方案。通过分析输出电压纹波,推导出C和ESR的计算模型,并据此进行了监测系统设计。最后进行了仿真验证。仿真结果和数据验证了理论的有效性。
