硅橡胶与金属黏附效应的产生与影响分析

为探讨橡胶密封件与金属法兰之间的黏附效应产生的原因及黏附效应对密封的影响,根据硅橡胶密封结构的使用特点,设计硅橡胶密封圈与金属法兰在不同温度、不同时间下的黏附实验.通过硅橡胶密封圈与防锈铝合金和2种不锈钢材料的对比实验发现,硅橡胶密封圈与不锈钢金属法兰易发生黏附,与防锈铝合金金属法兰不易发生黏附.通过对金属法兰表面接触...     

Coupling Anion-Capturer with Polymer Chains in Fireproof Gel Polymer Electrolyte Enables Dendrite-Free Sodium Metal Batteries

Sodium metal batteries (SMBs) using gel polymer electrolytes (GPEs) with high theoretical capacity and low production cost are regarded as a promising candidate for high energy-density batteries. However, the inherent flammability of GPEs and uncontrolled Na dendrite caused by inferior mechanical properties and interfacial stability hinder their practical applications. Herein, an anion-trapping fireproof composite gel electrolyte (AT-FCGE) is designed through a chemical grafting–coupling strategy, where functionalized boron nitride nanosheets (M-BNNs) used as both nanosized crosslinker and anion capturer are coupled with poly(ethylene glycol)diacrylate in poly(vinylidene fluoride-co-hexafluoropropylene) matrix, to expedite Na⁺ transport and suppress dendrite growth. Experimental and calculation studies suggest that the anion-trapping effect of M-BNNs with abundant Lewis-acid sites can promote the dissociation of salts, thus remarkably improving the ionic conductivity and Na⁺ transference number. Meanwhile, the formation of highly crosslinked semi-interpenetrating network can effectively in situ encapsulate non-flammable phosphate without sacrificing the mechanical properties. Consequently, the resulting AT-FCGE shows significantly enhanced Na⁺ conductivity, mechanical properties, and excellent interfacial stability. The AT-FCGE enables a long-cycle stability dendrite-free Na/Na symmetric cell, and prominent electrochemical performance is demonstrated in solid-state SMBs. The approach provides a broader promise for the great potential of fire-retardant gel electrolytes in high-performance SMBs and the beyond.     

Flexible Photonic Radiative Cooling Films: Fundamentals,Fabrication and Applications

Photonic structures designed at sub-wavelength scales have emerged as a promising avenue for various energy applications, including cooling devices, water harvesting, photovoltaics, and personal thermal management, which have significantly transformed the global energy landscape. Particularly, flexible photonic radiative cooling films, which facilitate heat dissipation from surfaces by emitting it into outer space via infrared radiation, have achieved great progress in recent years. In this review, the different approaches used to design photonic structures for manipulating solar reflectance and optimizing thermal emittance are summarized. On this basis, this review discusses advancements in flexible radiative cooling films that have been meticulously adhere to these design principles, alongside their cooling effects over recent years. Furthermore, a comprehensive overview of the progress is presented in the photonic integration with new functionality and the fabrication techniques of photonic structures. Lastly, this review highlights the remarkable potential of radiative coolers in various fields. In prospect, the widespread adoption of flexible photonic radiative cooling films holds immense promise for diverse applications.     

Combined experimental and DFT study on high-temperature thermochromism of Co-doped LaCrO3 coating for thermal indicator

Noncontact temperature measurement using thermochromic materials is vital in the field of temperature indication, but the related mechanisms behind thermochromic behavior are diverse and high complexity, and the color-temperature correspondence is poorly explored. This paper systematically studied the thermochromic mechanisms and color-temperature correspondence in the cobalt-doped LaCrO₃ coatings via experiment and density functional theory study. The coatings appear reversible thermochromism from green to black with temperature and composition, functions from room temperature to 700°C. This thermochromism is attributed to the lattice expansion and bandgap reduction as the temperature increase, and a model of temperature effect bandgap was proposed. Meanwhile, the coating temperature can be inferred from the color change because the CIE chromaticity coordinate of the coating varies linearly with temperature, and the mean relative error of thermochromic measurements is 8.28%. Furthermore, the cobalt doped introduces impurity energy levels and enhances the interaction between photons and carriers, which reduce the bandgap and increase the absorption in the visible spectrum resulting in darker colors. This work provides a stable and efficient high-temperature thermochromic coating that has a wide thermochromic temperature range and clear color-temperature correspondence, which shows broad application prospects in the field of thermal indication at high temperatures.     

微米级金属箔电导率无损测试

高导电性薄金属箔电导率难以准确测定一直是该研究领域的痛点问题。本文研究了金属箔厚度对超薄金属箔-空气界面电场反射、金属箔表面阻抗、涡流线圈阻抗的影响，进而提出了一种适用于厚度小于100 μm金属箔的电导率无损测试新方法。新方法利用两片厚度不同的同种金属箔定义了“厚度系数”，从而规避了界面处电场反射对测试的影响。研究结果表明新方法可应用到银、铜、铜铬锆箔等电导率处于80-110% IACS范围内的箔类材料，测试偏差可控制在~3%以内，且可以通过厚度设计缩小误差至小于2% IACS，远小于叠层结构法误差（~20%）。该研究将有助于完善科学研究和工业领域所需要的高导电超薄金属箔测试标准。