The microscopic Bouligand-type architectures of fish scales demonstrate a notable efficiency in enhancing the damage tolerance of materials;nevertheless,it is challenging to reproduce in metals.Here bioinspired tungst...The microscopic Bouligand-type architectures of fish scales demonstrate a notable efficiency in enhancing the damage tolerance of materials;nevertheless,it is challenging to reproduce in metals.Here bioinspired tungsten-copper composites with different Bouligand-type architectures mimicking fish scales were fabricated by infiltrating a copper melt into woven contextures of tungsten fibers.These composites exhibit a synergetic enhancement in both strength and ductility at room temperature along with an improved resistance to high-temperature oxidization.The strengths were interpreted by adapting the classical laminate theory to incorporate the characteristics of Bouligand-type architectures.In particular,under load the tungsten fibers can reorient adaptively within the copper matrix by their straightening,stretching,interfacial sliding with the matrix,and the cooperative kinking deformation of fiber grids,representing a successful implementation of the optimizing mechanisms of the Bouligand-type architectures to enhance strength and toughness.This study may serve to promote the development of new high-performance tungsten-copper composites for applications,e.g.,as electrical contacts or heat sinks,and offer a viable approach for constructing bioinspired architectures in metallic materials.展开更多
The arc erosion under medium direct currents in the argon flow was tested on tungsten-copper（W-Cu） contacts which were processed by hot extrusion and heat treatment. The scanning electron microscopy（SEM） and trans...The arc erosion under medium direct currents in the argon flow was tested on tungsten-copper（W-Cu） contacts which were processed by hot extrusion and heat treatment. The scanning electron microscopy（SEM） and transmission electron microscopy（TEM） were used to study the microstructure of the W-Cu powders and compacts. The contact resistance, arcing energy, and arcing time were continuously measured by JF04C contact materials test system. Changes in tungsten-copper contact surface were observed by SEM. The test results showed that the arcing time and arcing energy all increase with current and voltage, but the changes of average contact resistance are more complicated. For a short arcing time, the average contact resistance decreases with increasing current due to the vaporization of Cu. However, for a longer arcing time, it slightly increases due to the formation of high resistant films, compound copper tungsten. The formation of compound copper tungsten was confirmed by the increased Rc kept in the range from 1.1 to 1.6 mΩ. The compound copper tungsten is first exposed with a tungsten and copper-rich surface, and then totally exposed due to evaporation of copper from the surface. At last a stabilized surface is created and the crystals decrease from 8 μm to 2 μm caused by the arc erosion.展开更多
铜钨材料(copper tungsten material,CuW)是高压断路器应用最广泛的电触头材料,触头烧蚀性能直接影响高压断路器的使用寿命和电网安全。该文以不同W含量(70%、75%、80%、85%)的Gr(石墨烯)CuW触头为研究对象,安装于40.5 k V断路器,进行20...铜钨材料(copper tungsten material,CuW)是高压断路器应用最广泛的电触头材料,触头烧蚀性能直接影响高压断路器的使用寿命和电网安全。该文以不同W含量(70%、75%、80%、85%)的Gr(石墨烯)CuW触头为研究对象,安装于40.5 k V断路器,进行20次23 k A实验电流的电弧烧蚀实验。研究实验后触头质量、长度、接触电阻、表面宏观及截面微观烧蚀形貌变化,对比分析不同W含量的GrCuW触头耐烧蚀性能。结果表明,GrCuW中W含量为70%~80%时,W含量增加,弧触头烧蚀表面趋于平整,接触电阻下降,耐烧蚀性能提高。GrCuW80中80%的W和20%的GrCu平衡了触头的硬度、韧性及导电性能,使触头耐烧蚀性能最好。当W含量大于80%时,触头表面重熔W层增厚,烧蚀表面呈片状剥落,接触电阻增大,触头耐烧蚀性能下降。因此,GrCuW触头材料Cu与W的比例优化对CuW触头产品研发具有一定指导意义。展开更多
基金the financial support by the National Key R&D Program of China under grant number 2020YFA0710404the National Natural Science Foundation of China under grant number 51871216+5 种基金the KC Wong Education Foundation(GJTD-2020-09)the Liao Ning Revitalization Talents Programthe State Key Laboratory for Modification of Chemical Fibers and Polymer Materials at Donghua Universitythe Opening Project of Jiangsu Province Key Laboratory of High-End Structural Materials under grant number hsm1801the Youth Innovation Promotion Association CASsupport from the Multidisciplinary University Research Initiative to University of California Riverside,funded by the Air Force Office of Scientific Research(AFOSR-FA9550–15–1–0009)and subcontracted to the University of California Berkeley。
文摘The microscopic Bouligand-type architectures of fish scales demonstrate a notable efficiency in enhancing the damage tolerance of materials;nevertheless,it is challenging to reproduce in metals.Here bioinspired tungsten-copper composites with different Bouligand-type architectures mimicking fish scales were fabricated by infiltrating a copper melt into woven contextures of tungsten fibers.These composites exhibit a synergetic enhancement in both strength and ductility at room temperature along with an improved resistance to high-temperature oxidization.The strengths were interpreted by adapting the classical laminate theory to incorporate the characteristics of Bouligand-type architectures.In particular,under load the tungsten fibers can reorient adaptively within the copper matrix by their straightening,stretching,interfacial sliding with the matrix,and the cooperative kinking deformation of fiber grids,representing a successful implementation of the optimizing mechanisms of the Bouligand-type architectures to enhance strength and toughness.This study may serve to promote the development of new high-performance tungsten-copper composites for applications,e.g.,as electrical contacts or heat sinks,and offer a viable approach for constructing bioinspired architectures in metallic materials.
文摘The arc erosion under medium direct currents in the argon flow was tested on tungsten-copper（W-Cu） contacts which were processed by hot extrusion and heat treatment. The scanning electron microscopy（SEM） and transmission electron microscopy（TEM） were used to study the microstructure of the W-Cu powders and compacts. The contact resistance, arcing energy, and arcing time were continuously measured by JF04C contact materials test system. Changes in tungsten-copper contact surface were observed by SEM. The test results showed that the arcing time and arcing energy all increase with current and voltage, but the changes of average contact resistance are more complicated. For a short arcing time, the average contact resistance decreases with increasing current due to the vaporization of Cu. However, for a longer arcing time, it slightly increases due to the formation of high resistant films, compound copper tungsten. The formation of compound copper tungsten was confirmed by the increased Rc kept in the range from 1.1 to 1.6 mΩ. The compound copper tungsten is first exposed with a tungsten and copper-rich surface, and then totally exposed due to evaporation of copper from the surface. At last a stabilized surface is created and the crystals decrease from 8 μm to 2 μm caused by the arc erosion.
文摘铜钨材料(copper tungsten material,CuW)是高压断路器应用最广泛的电触头材料,触头烧蚀性能直接影响高压断路器的使用寿命和电网安全。该文以不同W含量(70%、75%、80%、85%)的Gr(石墨烯)CuW触头为研究对象,安装于40.5 k V断路器,进行20次23 k A实验电流的电弧烧蚀实验。研究实验后触头质量、长度、接触电阻、表面宏观及截面微观烧蚀形貌变化,对比分析不同W含量的GrCuW触头耐烧蚀性能。结果表明,GrCuW中W含量为70%~80%时,W含量增加,弧触头烧蚀表面趋于平整,接触电阻下降,耐烧蚀性能提高。GrCuW80中80%的W和20%的GrCu平衡了触头的硬度、韧性及导电性能,使触头耐烧蚀性能最好。当W含量大于80%时,触头表面重熔W层增厚,烧蚀表面呈片状剥落,接触电阻增大,触头耐烧蚀性能下降。因此,GrCuW触头材料Cu与W的比例优化对CuW触头产品研发具有一定指导意义。
