Impact wear behaviors of Hadfield manganese steel at different impact angles were investigated. The results of impact wear tests show that there exists a critical impact load for Hadfield steel. The wear rate suddenly...Impact wear behaviors of Hadfield manganese steel at different impact angles were investigated. The results of impact wear tests show that there exists a critical impact load for Hadfield steel. The wear rate suddenly turns down after some impact cycles when the impact load is greater than the critical load. The critical impact load is smaller than 8.2 J in this research because the nano-sized austenitic grains embedded in amorphous delay the crack propagation in subsurface. From high resolution transmission electron microscope (HRTEM) examination of subsurface microstructure, it is found that a large amount of nano-sized grains embedded in bulk amorphous matrix are fully developed and no martensitic transformation occurs during the impact wear process. The analytical results of worn surface morphology and debris indicate that the initiation of crack, propagation and spalling are restricted in the amorphous phase, resulting in the size distribution of debris in nano-sizes, which is the reason why the wear rate of Hadfield steel is greatly decreased at high impact load.展开更多
Here we report a femtosecond laser direct writing(a precise 3D printing also known as two-photon polymerization lithography) of hybrid organic-inorganic SZ2080^(TM)pre-polymer without using any photo-initiator and app...Here we report a femtosecond laser direct writing(a precise 3D printing also known as two-photon polymerization lithography) of hybrid organic-inorganic SZ2080^(TM)pre-polymer without using any photo-initiator and applying ~100 fs oscillator operating at 517 nm wavelength and 76 MHz repetition rate. The proof of concept was experimentally demonstrated and benchmarking 3D woodpile nanostructures, micro-scaffolds, free-form micro-object “Benchy” and bulk micro-cubes are successfully produced. The essential novelty underlies the fact that non-amplified laser systems delivering just 40-500 p J individual pulses are sufficient for inducing localized cross-linking reactions within hundreds of nanometers in cross sections. And it is opposed to the prejudice that higher pulse energies and lower repetition rates of amplified lasers are necessary for structuring non-photosensitized polymers. The experimental work is of high importance for fundamental understanding of laser enabled nanoscale 3D additive manufacturing and widens technology’ s field of applications where the avoidance of photo-initiator is preferable or is even a necessity, such as micro-optics, nano-photonics, and biomedicine.展开更多
Organic-inorganic nanohybrid materials repre- sent a wide range of nanoscaled synthetic materials con- sisting of both organic and inorganic components that are linked together by covalent or non-covalent interactions...Organic-inorganic nanohybrid materials repre- sent a wide range of nanoscaled synthetic materials con- sisting of both organic and inorganic components that are linked together by covalent or non-covalent interactions, which have been widely employed in various fields such as optoelectronics, catalysis and biomedicine. As a result of this special combination, nanohybrid materials assemble numerous extraordinary features that provide great opportunities to improve their stability, multifunctions, biocom- patibility, eco-friendliness and other physical and mechanical properties. This review highlights recent re- search developments of functional organic-inorganic nanohybrid materials and their specific applications in bioimaging including fluorescent, Raman, photoacoustic and combined bioimaging. Future research directions and perspectives in this rapidly developing field are also discussed.展开更多
基金Project(59771048) supported by the National Natural Science Foundation of China project(2002AA302509) supportedby the High Technology Research and Development Program of China
文摘Impact wear behaviors of Hadfield manganese steel at different impact angles were investigated. The results of impact wear tests show that there exists a critical impact load for Hadfield steel. The wear rate suddenly turns down after some impact cycles when the impact load is greater than the critical load. The critical impact load is smaller than 8.2 J in this research because the nano-sized austenitic grains embedded in amorphous delay the crack propagation in subsurface. From high resolution transmission electron microscope (HRTEM) examination of subsurface microstructure, it is found that a large amount of nano-sized grains embedded in bulk amorphous matrix are fully developed and no martensitic transformation occurs during the impact wear process. The analytical results of worn surface morphology and debris indicate that the initiation of crack, propagation and spalling are restricted in the amorphous phase, resulting in the size distribution of debris in nano-sizes, which is the reason why the wear rate of Hadfield steel is greatly decreased at high impact load.
基金Project(S-MIP-20-17) supported by the Research Council of LithuaniaProject(871124) supported by the EU Horizon 2020, Research and Innovation program LASERLAB-EUROPE JRA。
文摘Here we report a femtosecond laser direct writing(a precise 3D printing also known as two-photon polymerization lithography) of hybrid organic-inorganic SZ2080^(TM)pre-polymer without using any photo-initiator and applying ~100 fs oscillator operating at 517 nm wavelength and 76 MHz repetition rate. The proof of concept was experimentally demonstrated and benchmarking 3D woodpile nanostructures, micro-scaffolds, free-form micro-object “Benchy” and bulk micro-cubes are successfully produced. The essential novelty underlies the fact that non-amplified laser systems delivering just 40-500 p J individual pulses are sufficient for inducing localized cross-linking reactions within hundreds of nanometers in cross sections. And it is opposed to the prejudice that higher pulse energies and lower repetition rates of amplified lasers are necessary for structuring non-photosensitized polymers. The experimental work is of high importance for fundamental understanding of laser enabled nanoscale 3D additive manufacturing and widens technology’ s field of applications where the avoidance of photo-initiator is preferable or is even a necessity, such as micro-optics, nano-photonics, and biomedicine.
基金supported by the National Research Foundation(NRF),Prime Minister’s Office,Singapore,under its NRF Fellowship(NRF2009NRF-RF001-015)Campus for Research Excellence and Technological Enterprise(CREATE)Programme-Singapore Peking University Research Centre for a Sustainable Low-Carbon Future+1 种基金the NTU-A*STAR Silicon Technologies Centre of Excellence under the program Grant No.11235150003the NTU-Northwestern Institute for Nanomedicine
文摘Organic-inorganic nanohybrid materials repre- sent a wide range of nanoscaled synthetic materials con- sisting of both organic and inorganic components that are linked together by covalent or non-covalent interactions, which have been widely employed in various fields such as optoelectronics, catalysis and biomedicine. As a result of this special combination, nanohybrid materials assemble numerous extraordinary features that provide great opportunities to improve their stability, multifunctions, biocom- patibility, eco-friendliness and other physical and mechanical properties. This review highlights recent re- search developments of functional organic-inorganic nanohybrid materials and their specific applications in bioimaging including fluorescent, Raman, photoacoustic and combined bioimaging. Future research directions and perspectives in this rapidly developing field are also discussed.
