Authors: Su Feng Yin, Feng Ruan, Jian Yu Wang
Abstract: The article focuses on the discussion of size relationship of melt viscosity of ultra-thin wall injection molding, revising the viscosity model of traditional stimulant Cross-WLF. It takes the theory of Uhland wall-slip, trying to analyze the influence which the wall-slip of the molding makes on injection molding. It also points out the limitation of constant heat transfer coefficient in the molding. The change rules of the heat transfer coefficient is among the study. Using the method of numerical simulation and experience, the article verifies the consistency of experience result and the change of the factors, such as using ultra-thin viscosity model, wall-slip and the change of heat transfer coefficient while doing the simulation.
1145
Authors: Hui Ling Gong, Xiao Hui Wang, Shao Peng Zhang, Xin Ye Yang, Long Tu Li
Abstract: Microstructure control in thin-layer multilayer ceramic capacitors (MLCCs) is one of the challenges for increasing capacitive volumetric efficiency and high voltage dielectric properties. In this paper, the X5R-MLCCs with ultra-thin dielectric layers (~1.2 μm) owning uniform grain size distribution were prepared by wet casting process. The microstructures and dielectric properties of the MLCCs were investigated. The existence of core-shell structure was proved by transmission electron microscopy observation and energy dispersive spectroscopy analysis. The existence of core-shell structure makes the temperature coefficient of capacitance (TCC) performance meet X5R standard. Moreover, a highly accelerated lifetime test (HALT) result shows that MLCCs with ultra-thin layers under high electric field are more easily to fail with increasing test temperatures. And the results reveal that the activation energy is similar to the value reported for mid-dielectric constant dielectrics.
695
Authors: Da Zhi Wang, Xiao Hu Zhu, Wen Zha, Tong Qun Ren, Ming Qiang Li, Jun Sheng Liang, Chong Liu
Abstract: In this work, a quaternized polysulfone/PTFE/H3PO4 composite membrane was prepared and used to a high temperature sustainable proton exchange membrane (HTPEM). This HTPEM was prepared based on a porous PTFE membrane, which can sustainable for 200 °C. Pt/C nano-suspension was prepared and deposited layer-by-layer on the gas diffusion layer (GDL) using electrohydrodynamic atomization (EHDA) deposition technique for the formation of cathode and anode catalyst layers (CLs). The CLs presented well packed and porous features. This EHDA deposited cathode and anode CLs, GDL and HTPEM were assembled to a membrane electrode assembly (MEA) and high temperature methanol fuel cell (HTMFC). The results showed that low concentration and high flow rate of methanol aqueous solution led to the loss of phosphoric acid on HTPEM, which resulted in the decline of the HTPEM. When the concentration and the flow rate of the methanol aqueous solution was increased and reduced, respectively, the cell can work properly at a temperature of 170 °C.
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