In ab initio molecular dynamics(AIMD)simulations of chemical reactions,it is important but difficult to identify the chemical species in the trajectory automatically and quickly.In this paper,based on the chemical gra...In ab initio molecular dynamics(AIMD)simulations of chemical reactions,it is important but difficult to identify the chemical species in the trajectory automatically and quickly.In this paper,based on the chemical graph theory,an algorithm for molecular species identification,according to the molecular coordinates and empirical bond length database,is presented.As an example,the chemical species in condensed glycine at room temperature are investigated with our algorithm in detail.The chemical species,including canonical and zwitterionic glycine,their protonated and de-protonated states,and the free protons,are all identified,counted and recorded correctly.Potential applications and further development of the algorithm are also discussed.展开更多
Corrosion would lead to the failure of materials during service,causing huge economic losses and catastrophic accidents,particularly in chemical industries.In this work,a series of novel high-entropy alloys(HEAs)(FeCo...Corrosion would lead to the failure of materials during service,causing huge economic losses and catastrophic accidents,particularly in chemical industries.In this work,a series of novel high-entropy alloys(HEAs)(FeCoCrNiMo_(x)Nb_(x))with exceptional corrosion resistance were designed.The phase composition,corrosion resistance,and passive film properties were determined through micro-characterization and electrochemical tests.First-principles calculations were further performed to unveil the corrosion resistance mechanism at the atomic level,especially the influence of elements on the corrosion resistance.It is found that the appropriate increase in the contents of Mo/Nb elements leads to the increased Laves phase in the HEAs and enhances the corrosion resistance of the HEAs.However,the excessive addition of Mo/Nb elements will cause more severe microgalvanic corrosion between FCC and Laves phases,resulting in a decrease in corrosion resistance.Theoretical calculations demonstrate that the Laves phase is more resistant to the attack of corrosive species.Additionally,the presences of Mo,Nb,and Cr elements in the HEAs facilitate the adsorption of H_(2)O/O on the HEAs surface,which promotes the formation of a protective passive film,and then provides better protection for the HEAs.展开更多
An advanced AlCrSiN/AlCrN/CrN/Cr multilayer coating was developed via hybrid multiarc ion plating and high-power impulse magnetron sputtering.The multilayer design enhanced the substrate-coating compatibility,achievin...An advanced AlCrSiN/AlCrN/CrN/Cr multilayer coating was developed via hybrid multiarc ion plating and high-power impulse magnetron sputtering.The multilayer design enhanced the substrate-coating compatibility,achieving a critical load of 87.8 N.Silicon doping induced nanocrystallization and amorphization,increasing the hardness to 26 GPa.At high temperatures,a nanoscale Cr-rich(Cr,Al)_(2)O_(3) layer was formed,effectively inhibiting oxygen diffusion.The coating underwent unique phase transformations,during which Cr_(2)N and amorphous Si3N4 were converted into dispersed SiCr_(3) nanoparticles,which stabilized Cr atoms and suppressed their outward diffusion.Ab initio molecular dynamics simulations revealed that Cr atoms exhibited higher chemical activity and oxygen-capture capability than Al atoms and Si atoms served as diffusion barriers by pinning onto the oxidized surface,considerably improving the oxidation resistance of the coating.展开更多
基金The authors thank Dr.Gareth Tribello of Queen’s University Belfast for helpful discussions on the algorithm.This work was partially supported by the program of the Key Laboratory for Aerosol-Cloud-Precipitation of CMA-NUIST(No.KDW1304)the National Natural Science Foundation of China(Grant No.11105075).
文摘In ab initio molecular dynamics(AIMD)simulations of chemical reactions,it is important but difficult to identify the chemical species in the trajectory automatically and quickly.In this paper,based on the chemical graph theory,an algorithm for molecular species identification,according to the molecular coordinates and empirical bond length database,is presented.As an example,the chemical species in condensed glycine at room temperature are investigated with our algorithm in detail.The chemical species,including canonical and zwitterionic glycine,their protonated and de-protonated states,and the free protons,are all identified,counted and recorded correctly.Potential applications and further development of the algorithm are also discussed.
基金financially supported by the National Natural Science Foundation of China(Nos.52371064 and U21A20113).
文摘Corrosion would lead to the failure of materials during service,causing huge economic losses and catastrophic accidents,particularly in chemical industries.In this work,a series of novel high-entropy alloys(HEAs)(FeCoCrNiMo_(x)Nb_(x))with exceptional corrosion resistance were designed.The phase composition,corrosion resistance,and passive film properties were determined through micro-characterization and electrochemical tests.First-principles calculations were further performed to unveil the corrosion resistance mechanism at the atomic level,especially the influence of elements on the corrosion resistance.It is found that the appropriate increase in the contents of Mo/Nb elements leads to the increased Laves phase in the HEAs and enhances the corrosion resistance of the HEAs.However,the excessive addition of Mo/Nb elements will cause more severe microgalvanic corrosion between FCC and Laves phases,resulting in a decrease in corrosion resistance.Theoretical calculations demonstrate that the Laves phase is more resistant to the attack of corrosive species.Additionally,the presences of Mo,Nb,and Cr elements in the HEAs facilitate the adsorption of H_(2)O/O on the HEAs surface,which promotes the formation of a protective passive film,and then provides better protection for the HEAs.
基金financially supported by the National Science and Technology Major Project(No.2024ZD1404705)。
文摘An advanced AlCrSiN/AlCrN/CrN/Cr multilayer coating was developed via hybrid multiarc ion plating and high-power impulse magnetron sputtering.The multilayer design enhanced the substrate-coating compatibility,achieving a critical load of 87.8 N.Silicon doping induced nanocrystallization and amorphization,increasing the hardness to 26 GPa.At high temperatures,a nanoscale Cr-rich(Cr,Al)_(2)O_(3) layer was formed,effectively inhibiting oxygen diffusion.The coating underwent unique phase transformations,during which Cr_(2)N and amorphous Si3N4 were converted into dispersed SiCr_(3) nanoparticles,which stabilized Cr atoms and suppressed their outward diffusion.Ab initio molecular dynamics simulations revealed that Cr atoms exhibited higher chemical activity and oxygen-capture capability than Al atoms and Si atoms served as diffusion barriers by pinning onto the oxidized surface,considerably improving the oxidation resistance of the coating.
