The paper reports the deposition(by magnetron sputtering) and properties of polycrystalline boron nitride (BN) layers on commercial inoculating alloy wires. As is characterized by means of Fourier transform infra...The paper reports the deposition(by magnetron sputtering) and properties of polycrystalline boron nitride (BN) layers on commercial inoculating alloy wires. As is characterized by means of Fourier transform infrared(FTIR) spectroscopy, electron energy dispersive X-ray(EDX) spectroscopy and scanning electron microscopy(SEM), the thin BN layers consist of hexagonal and orthorhombic BN phases and are smooth without cracks. Organism transfer- ring-circles experiments reveal that the adhesion between the BN layer and alloy wire is very good after tens of cycles. It is demonstrated that the BN layers covered wires are biomaterial lubricious and self-cleaning. As a result, BN layer would effectively enhance the function and efficiency of inoculating alloy wires, which could be widely ap- plied to bio-experimentation and biomedicine apparatuses.展开更多
The nitrided layers mainly containing TiN dendrites were fabricated by direct current nitrogen arc melting method. The test results show that the layers are harder and more resistant to wear than the titanium substrat...The nitrided layers mainly containing TiN dendrites were fabricated by direct current nitrogen arc melting method. The test results show that the layers are harder and more resistant to wear than the titanium substrate. Arc traveling speeds and arc currents have an effect on both the microstructures and the properties of the layers. Decreasing the arc traveling speed or increasing the arc current can obviously enhance the hardness and the wear resistance of the nitrided layers.展开更多
The nitrided layer on Ti6A14V substrate was prepared by the plasma nitriding technique. The sample was characterized by X-ray diffraction (XRD), glow discharge optical emission spectroscopy (GDOES), X-ray photoele...The nitrided layer on Ti6A14V substrate was prepared by the plasma nitriding technique. The sample was characterized by X-ray diffraction (XRD), glow discharge optical emission spectroscopy (GDOES), X-ray photoelectron spectroscopy (XPS), and rough-meter. X- ray diffraction analysis reveals that TiN, Ti2N and Ti phase exist in the nitrided layer subsurface. GDOES analysis shows the thickness of the nitrided layer is about 3 ~tm. XPS analysis shows that there is higher N, lower A1 and lower V in the nitrided layer surface than in the Ti6A14V surface. Rough-meter analysis results show the roughness of the nitrided layer is greater than that of Ti6A14V alloy base. The bacteria adherence property of the nitrided layer on Ti6A14V substrate on the Streptococcus mutans was investigated and compared with that of Ti6A14V alloy by fluorescence microscope. It shows that the nitrided layer inhibits the bacteria adherence.展开更多
Devices of electric double-layer transistors (EDLTs) with ionic liquid have been employed as an effective way to dope carriers over a wide range. However, the induced electronic states can hardly survive in the mate...Devices of electric double-layer transistors (EDLTs) with ionic liquid have been employed as an effective way to dope carriers over a wide range. However, the induced electronic states can hardly survive in the materials after releasing the gate voltage VG at temperatures higher than the melting point of the selected ionic liquid. Here we show that a permanent superconductivity with transition temperature Tc of 24 and 15K is realized hi single crystals and polycrystalline samples of HfNCI and ZrNCI upon applying proper VG's at different temperatures. Reversible change between insulating and superconducting states can be obtained by applying positive and negative VG at low temperature such as 220K, whereas VG 's applied at 250K induce the irreversible superconducting transition. The upper critical field He2 of the superconducting states obtained at different gating temperatures shows similar temperature dependence. We propose a reasonable scenario that partial vacancy of Cl ions could be caused by applying proper VG's at slightly higher processing temperatures, which consequently results in a permanent electron doping in the system. Such a technique shows great potential to systematically tune the bulk electronic state in the similar two-dimensional systems.展开更多
This study aims to draw an exact boundary for microstructural and mechanical behaviors in terms of pulsed plasma nitriding conditions.The pulsed plasma nitriding treatment was applied to AISI 304 austenitic stainless ...This study aims to draw an exact boundary for microstructural and mechanical behaviors in terms of pulsed plasma nitriding conditions.The pulsed plasma nitriding treatment was applied to AISI 304 austenitic stainless steel at different temperatures and durations.Results reveal that nitriding depth increased as process temperature and duration increase.The nitriding depth remarkably increased at 475℃for 8 h and at 550℃for 4 h.An austenite structure was transformed into a metastable nitrogen-oversaturated body-centered tetragonal expanded austenite(S-phase)during low-temperature plasma nitriding.The S-phase was converted to CrN precipitation at 475℃for 8 h and at 550℃for 4 h.Surface hardness and fatigue limit increased through plasma nitriding regardless of process conditions.The best surface hardness and fatigue limit were obtained at 550℃for 4 h because of the occurrence of CrN precipitation.展开更多
Titanium-aluminum-nitride(TiAlN) films were grown by plasma-enhanced atomic layer deposition(PEALD)on 316 L stainless steel at a deposition temperature of 200 °C. A supercycle, consisting of one AlN and ten T...Titanium-aluminum-nitride(TiAlN) films were grown by plasma-enhanced atomic layer deposition(PEALD)on 316 L stainless steel at a deposition temperature of 200 °C. A supercycle, consisting of one AlN and ten TiN subcycles, was used to prepare TiAlN films with a chemical composition of Ti(0.25)Al(0.25)N(0.50). The addition of AlN to TiN resulted in an increased electrical resistivity of TiAlN films of 2800 μΩ cm, compared with 475 μΩ cm of TiN films, mainly due to the high electrical resistivity of AlN and the amorphous structure of TiAlN. However, potentiostatic polarization measurements showed that amorphous TiAlN films exhibited excellent corrosion resistance with a corrosion current density of 0.12 μA/cm^2, about three times higher than that of TiN films, and about 12.5 times higher than that of 316 L stainless steel.展开更多
We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes (g-CNN) by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microsc...We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes (g-CNN) by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microscopy, femtosecond transient absorption spectroscopy, and picosecond time-correlated single photon counting measurement. For the first time, we found that g-CNN displays a layer-dependent indirect bandgap and layer-dependent charge carrier kinetics.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.51072066, 50772041), the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20100061110083) and the New Century Excellent Talents in Univer- sities of China(No.NCET-06-0303).
文摘The paper reports the deposition(by magnetron sputtering) and properties of polycrystalline boron nitride (BN) layers on commercial inoculating alloy wires. As is characterized by means of Fourier transform infrared(FTIR) spectroscopy, electron energy dispersive X-ray(EDX) spectroscopy and scanning electron microscopy(SEM), the thin BN layers consist of hexagonal and orthorhombic BN phases and are smooth without cracks. Organism transfer- ring-circles experiments reveal that the adhesion between the BN layer and alloy wire is very good after tens of cycles. It is demonstrated that the BN layers covered wires are biomaterial lubricious and self-cleaning. As a result, BN layer would effectively enhance the function and efficiency of inoculating alloy wires, which could be widely ap- plied to bio-experimentation and biomedicine apparatuses.
文摘The nitrided layers mainly containing TiN dendrites were fabricated by direct current nitrogen arc melting method. The test results show that the layers are harder and more resistant to wear than the titanium substrate. Arc traveling speeds and arc currents have an effect on both the microstructures and the properties of the layers. Decreasing the arc traveling speed or increasing the arc current can obviously enhance the hardness and the wear resistance of the nitrided layers.
基金Funded by the National Natural Science Foundation of China(No.51171125)the National High-Tech Research and Development Program of China(863 Program)(No.2007AAO3Z521)+3 种基金the Natural Science Foundation of of Shanxi Province(No.2012011021-4,2012021021-8)the Shanxi Province Foundation for Returned Overseas Scholars(No 2011-038)the Shanxi Province Programs for Science and Technology Development(20110321051)the Taiyuan University of Technology Graduate Innovation Fund
文摘The nitrided layer on Ti6A14V substrate was prepared by the plasma nitriding technique. The sample was characterized by X-ray diffraction (XRD), glow discharge optical emission spectroscopy (GDOES), X-ray photoelectron spectroscopy (XPS), and rough-meter. X- ray diffraction analysis reveals that TiN, Ti2N and Ti phase exist in the nitrided layer subsurface. GDOES analysis shows the thickness of the nitrided layer is about 3 ~tm. XPS analysis shows that there is higher N, lower A1 and lower V in the nitrided layer surface than in the Ti6A14V surface. Rough-meter analysis results show the roughness of the nitrided layer is greater than that of Ti6A14V alloy base. The bacteria adherence property of the nitrided layer on Ti6A14V substrate on the Streptococcus mutans was investigated and compared with that of Ti6A14V alloy by fluorescence microscope. It shows that the nitrided layer inhibits the bacteria adherence.
基金Supported by the National Natural Science Foundation of China under Grant No 11704403the National Key Research Program of China under Grant No 2016YFA0401000 and 2016YFA0300604the Strategic Priority Research Program(B)of Chinese Academy of Sciences under Grant No XDB07020100
文摘Devices of electric double-layer transistors (EDLTs) with ionic liquid have been employed as an effective way to dope carriers over a wide range. However, the induced electronic states can hardly survive in the materials after releasing the gate voltage VG at temperatures higher than the melting point of the selected ionic liquid. Here we show that a permanent superconductivity with transition temperature Tc of 24 and 15K is realized hi single crystals and polycrystalline samples of HfNCI and ZrNCI upon applying proper VG's at different temperatures. Reversible change between insulating and superconducting states can be obtained by applying positive and negative VG at low temperature such as 220K, whereas VG 's applied at 250K induce the irreversible superconducting transition. The upper critical field He2 of the superconducting states obtained at different gating temperatures shows similar temperature dependence. We propose a reasonable scenario that partial vacancy of Cl ions could be caused by applying proper VG's at slightly higher processing temperatures, which consequently results in a permanent electron doping in the system. Such a technique shows great potential to systematically tune the bulk electronic state in the similar two-dimensional systems.
基金the Scientific and Technological Research Council of Turkey(TUBITAK)for the support of this study(Grant No:215M134)。
文摘This study aims to draw an exact boundary for microstructural and mechanical behaviors in terms of pulsed plasma nitriding conditions.The pulsed plasma nitriding treatment was applied to AISI 304 austenitic stainless steel at different temperatures and durations.Results reveal that nitriding depth increased as process temperature and duration increase.The nitriding depth remarkably increased at 475℃for 8 h and at 550℃for 4 h.An austenite structure was transformed into a metastable nitrogen-oversaturated body-centered tetragonal expanded austenite(S-phase)during low-temperature plasma nitriding.The S-phase was converted to CrN precipitation at 475℃for 8 h and at 550℃for 4 h.Surface hardness and fatigue limit increased through plasma nitriding regardless of process conditions.The best surface hardness and fatigue limit were obtained at 550℃for 4 h because of the occurrence of CrN precipitation.
基金supported by the Global Frontier R&D Program (2013M3A6B1078874) on Center for Hybrid Interface Materials (HIM) funded by the Ministry of Science, ICT & Future Planning, Republic of Koreasupported by a grant from the Industrial R&D Program for Core Technology of Materials funded by the Ministry of Industry and Energy (10060331), Republic of Korea
文摘Titanium-aluminum-nitride(TiAlN) films were grown by plasma-enhanced atomic layer deposition(PEALD)on 316 L stainless steel at a deposition temperature of 200 °C. A supercycle, consisting of one AlN and ten TiN subcycles, was used to prepare TiAlN films with a chemical composition of Ti(0.25)Al(0.25)N(0.50). The addition of AlN to TiN resulted in an increased electrical resistivity of TiAlN films of 2800 μΩ cm, compared with 475 μΩ cm of TiN films, mainly due to the high electrical resistivity of AlN and the amorphous structure of TiAlN. However, potentiostatic polarization measurements showed that amorphous TiAlN films exhibited excellent corrosion resistance with a corrosion current density of 0.12 μA/cm^2, about three times higher than that of TiN films, and about 12.5 times higher than that of 316 L stainless steel.
基金Financial supports by the National Natural Science Foundation of China (No. 21373269)the Fundamental Research Funds for the Central Universities and the Research Funds of Renmin University of China(No. 10XNJ047)
文摘We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes (g-CNN) by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microscopy, femtosecond transient absorption spectroscopy, and picosecond time-correlated single photon counting measurement. For the first time, we found that g-CNN displays a layer-dependent indirect bandgap and layer-dependent charge carrier kinetics.