The corrosion resistance of 2024 alloys and Cf/2024 composites in 3.5% NaCl aqueous solution at normal temperature was studied by IM6e electrochemical measurement system, scanning electron microscopy(SEM) and electron...The corrosion resistance of 2024 alloys and Cf/2024 composites in 3.5% NaCl aqueous solution at normal temperature was studied by IM6e electrochemical measurement system, scanning electron microscopy(SEM) and electron diffraction scanning(EDS). The results indicate that CeO2 can raise the corrosion potential of the 2024 alloys and the Cf /2024 composites, prevent the pitting on the alloys and composites surface, and restrain the reaction of divided hydrogen, refine grain, and make the surface more even.展开更多
Realizing low contact resistance between graphene and metal electrodes remains a well-known challenge for building high-performance graphene devices. In this work, we attempt to reduce the contact resistance in graphe...Realizing low contact resistance between graphene and metal electrodes remains a well-known challenge for building high-performance graphene devices. In this work, we attempt to reduce the contact resistance in graphene transistors and further explore the resistance limit between graphene and metal contacts. The Pd/graphene contact resistance at room temperature is reduced below the 100 Ω·μm level both on mechanically exfoliated and chemical-vapor-deposition graphene by adopting high-purity palladium and high-quality graphene and controlling the fabrication process to not contaminate the interface. After excluding the parasitic series resistances from the measurement system and electrodes, the retrieved contact resistance is shown to be systematically and statistically less than 100 Ω·μm, with a minimum value of 69 Ω·μm, which is very close to the theoretical limit. Furthermore, the contact resistance shows no clear dependence on temperature in the range of 77-300 K; this is attributed to the saturation of carrier injection efficiency between graphene and Pd owing to the high quality of the graphene samples used, which have a sufficiently long carrier mean-free-path.展开更多
文摘The corrosion resistance of 2024 alloys and Cf/2024 composites in 3.5% NaCl aqueous solution at normal temperature was studied by IM6e electrochemical measurement system, scanning electron microscopy(SEM) and electron diffraction scanning(EDS). The results indicate that CeO2 can raise the corrosion potential of the 2024 alloys and the Cf /2024 composites, prevent the pitting on the alloys and composites surface, and restrain the reaction of divided hydrogen, refine grain, and make the surface more even.
基金This work was supported by the Ministry of Sdence and Technology of China （Grant Nos. 2011CB933001 and 2011CB933002）, National Natural Science Foundation of China （Grant Nos. 61322105, 61271051, 61321001, and 61390504）, and Beijing Municipal Science and Technology Commission （Grant Nos. Z131100003213021 and D141100000614001）.
文摘Realizing low contact resistance between graphene and metal electrodes remains a well-known challenge for building high-performance graphene devices. In this work, we attempt to reduce the contact resistance in graphene transistors and further explore the resistance limit between graphene and metal contacts. The Pd/graphene contact resistance at room temperature is reduced below the 100 Ω·μm level both on mechanically exfoliated and chemical-vapor-deposition graphene by adopting high-purity palladium and high-quality graphene and controlling the fabrication process to not contaminate the interface. After excluding the parasitic series resistances from the measurement system and electrodes, the retrieved contact resistance is shown to be systematically and statistically less than 100 Ω·μm, with a minimum value of 69 Ω·μm, which is very close to the theoretical limit. Furthermore, the contact resistance shows no clear dependence on temperature in the range of 77-300 K; this is attributed to the saturation of carrier injection efficiency between graphene and Pd owing to the high quality of the graphene samples used, which have a sufficiently long carrier mean-free-path.
