Zinc and Zn-Ni alloy compositionally modulated multilayer （CMM） coatings were electrodeposited on to a steel substrate by the successive deposition of zinc and Zn-Ni alloy sublayers from dual baths. The coated sampl...Zinc and Zn-Ni alloy compositionally modulated multilayer （CMM） coatings were electrodeposited on to a steel substrate by the successive deposition of zinc and Zn-Ni alloy sublayers from dual baths. The coated samples were evaluated in terms of the surface appearance, surface and cross-sectional morphologies, as well as corrosion resistance. The microstructural characteristics that were examined using the field emission gun scanning electron microscopy （FEGSEM） confirmed the layered structure, grain refinement of the zinc and Zn-Ni alloy CMM coatings, and revealed the existence of microcracks caused by the internal stress in the thick Zn-Ni alloy sublayers. The corrosion resistance that was evaluated by means of the salt spray test shows that the zinc and Zn-Ni alloy CMM coatings were more corrosion-resistant than the monolithic coatings of zinc or Zn-Ni alloy of the same thickness. The possible reasons for the better protective performance of Zn-Ni/Zn CMM coatings were given on the basis of the analysis on the micrographic features of zinc and Zn-Ni alloy CMM eoatings after the corrosion test. A probable corrosion mechanism of zinc and Zn-Ni alloy CMM coatings was also proposed.展开更多
Varieties of zinc and Zn-Co alloy compositionally modulated multilayer （CMM） coatings were electrodeposited onto steel substrates using dual bath technique. The surface and cross-sectional morphologies of coated sam...Varieties of zinc and Zn-Co alloy compositionally modulated multilayer （CMM） coatings were electrodeposited onto steel substrates using dual bath technique. The surface and cross-sectional morphologies of coated samples were examined using scanning electron microscopy （ SEM ）. The existence of iuternal stress in ZnCo alloy deposits was confirmed by the cross-sectional morphalogies for the occurrence of micro-cracks in the thick Zn-Co alloy deposit alone. The corrosion performance was evaluated using neutral salt spray testing, corrosion potential measurement and anodic polarization methods. The experimental results slum, that the zinc and Zn- Co alloy CMM coatings were more corrosion-resistant than the monolithic coatings of zinc or Zn-Co alloy alone with a similar thickness. The analysis on the micrographic features of zinc and Zn-Co alloy CMM coatings, using field emission gun scanning electron microscopy （FEGSEM） after corrosion testing, explains the probable reusons why the Zn-Co/ Zn CMM coating system has a better protective performance.展开更多
The effects of pulse parameters on the cobalt content, surface morphologies and grain size of Zn-Co alloy deposits were studied using a pulse plating technique with a square-wave current containing reverse pulse. Aver...The effects of pulse parameters on the cobalt content, surface morphologies and grain size of Zn-Co alloy deposits were studied using a pulse plating technique with a square-wave current containing reverse pulse. Average current density and reverse anodic current density amongst the variables investigated have very strong effects on the cobalt content in the Zn-Co alloy deposits. Grain size, surface appearance and internal stress in the deposit were improved significantly by introducing the reverse current. Varieties of Zn-Co alloy compositionally modulated multilayer (CMM) coatings with large differences in cobalt contents for different sublayers were electrodeposited by designing corresponding waveforms using a computer-aided pulse plater and characterized in terms of surface morphologies. Cross-sectional morphologies of the Zn-Co alloy CMM coatings, examined using field emission gun scanning electron microscopy (FEGSEM), confirmed the layered structure.展开更多
The extinction ratio and insertion loss of spatial light modulator are subject to the material problem, thus limiting its applications. One reflection-type silicon-based spatial light modulator with high reflective ma...The extinction ratio and insertion loss of spatial light modulator are subject to the material problem, thus limiting its applications. One reflection-type silicon-based spatial light modulator with high reflective materials outside the Fabry-Perot cavity is demonstrated in this paper. The reflectivity values of the outside-cavity materials with different film layer numbers are simulated. The reflectivity values of 6-pair Ta2O5/SiO2 films at 1550 nm are experimentally verified to be as high as 99.9%. The surfaces of 6-pair Ta2O5/SiO2 films are smooth: their root-mean-square roughness values are as small as 0.53 nm. The insertion loss of the device at 1550 nm is only 1.2 dB. The high extinction ratio of the device at 1550 nm and 11 V is achieved to be 29.7 dB. The spatial light modulator has a high extinction ratio and low insertion loss for applications.展开更多
Zinc and Zn-Ni alloy compositionally modulated multilayer （CMM） coatings were electrodeposited from dual baths. The coated samples were evaluated in terms of surface appearance, surface and cross-sectional morpholog...Zinc and Zn-Ni alloy compositionally modulated multilayer （CMM） coatings were electrodeposited from dual baths. The coated samples were evaluated in terms of surface appearance, surface and cross-sectional morphologies, as well as corrosion resistance. The results obtained from the salt spray test show that the zinc and Zn-Ni alloy CMM coatings are more corrosion-resistant than the monolithic coatings of zinc or Zn-Ni alloy alone with a similar thickness. The corrosion potential measurement and anodic polarisation tests were undertaken to examine the probable corrosion mechanisms of zinc and Zn-Ni alloy CMM coatings. Analysis on the micrographic features of zinc and Zn-Ni alloy CMM coatings after the corrosion test explains the probable reasons why the Zn-Ni/Zn CMM coatings have a better protective performance. Surface morphologies and compositional analysis of the remaining coating material of Zn-Ni alloy deposit after the corrosion test confirms the dezincification mechanism of the Zn-Ni alloy deposit during the corrosion process.展开更多
In this paper, graphite-like carbon （GLC） films with Cr buffer layer were fabricated by DC magnetron sputtering technique with the thickness ratio of Cr to GLC films varying from 1：2 to 1：20. The effect of Cr]GLC ...In this paper, graphite-like carbon （GLC） films with Cr buffer layer were fabricated by DC magnetron sputtering technique with the thickness ratio of Cr to GLC films varying from 1：2 to 1：20. The effect of Cr]GLC modulation ratio on microstructure, mechanical and tribological properties in artificial seawater was mainly investigated by scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, nano-indenter and a reciprocating sliding tribo-meter. The propagation of defects plays an important role in the evolution of delamination, which is critical to wear failure of GLC films in artificial seawa- ter. Designing the proper multilayer structure could inhibit the defects propagation and thus protect the basis material. The multilayer Cr/GLC film with optimized ratio of 1：3 demonstrates a low average friction coefficient of 0.08 ± 0.006 and wear rate of （2.3 ± 0.3） × 10^-8 mm3/（N m） in artificial seawater, respectively.展开更多
Si/a-C:H(Ag)multilayer films with different modulation periods are prepared to test their potential applications in human body.The composition,microstructure,mechanical and tribological properties in the simulated bod...Si/a-C:H(Ag)multilayer films with different modulation periods are prepared to test their potential applications in human body.The composition,microstructure,mechanical and tribological properties in the simulated body fluid are investigated.The results show the concentration of Ag first decreases and then increases with the modulation period decreasing from 984 nm to 250 nm.Whereas the C content has an opposite variation trend.Notably,the concentration of Ag plays a more important role than the modulation period in the properties of the multilayer film.The a-C:H sublayer of the film with an appropriate Ag concentration(8.97 at.%)(modulation period of 512 nm)maintains the highest sp3/sp2 ratio,surface roughness and hardness,and excellent tribological property in the stimulated body fluid.An appropriate number of Ag atoms and size of Ag atom allow the Ag atoms to easily enter into the contact interface for load bearing and lubricating.This work proves that the Ag nanoparticles in the a-C:H sublayer plays a more important role in the tribological properties of the composite-multilayer film in stimulated body fluid condition.展开更多
The novel BaTiO3/BiFeO3/TiO2 multilayer heterojunction is prepared on a fluorine-doped tinoxide(FTO) substrate by the sol–gel method. The results indicate that the Pt/Ba TiO3/BiFeO3/TiO2/FTO heterojunction exhibits s...The novel BaTiO3/BiFeO3/TiO2 multilayer heterojunction is prepared on a fluorine-doped tinoxide(FTO) substrate by the sol–gel method. The results indicate that the Pt/Ba TiO3/BiFeO3/TiO2/FTO heterojunction exhibits stable bipolar resistive switching characteristic, good retention performance, and reversal characteristic. Under different pulse voltages and light fields, four stable resistance states can also be realized. The analysis shows that the main conduction mechanism of the resistive switching characteristic of the heterojunction is space charge limited current(SCLC) effect. After the comprehensive analysis of the band diagram and the P–E ferroelectric property of the multilayer heterojunction, we can deduce that the SCLC is formed by the effect of the oxygen vacancy which is controlled by ferroelectric polarizationmodulated change of interfacial barrier. And the effective photo-generated carrier also plays a regulatory role in resistance state(RS), which is formed by the double ferroelectric layer Ba TiO3/BiFeO3 under different light fields. This research is of potential application values for developing the multi-state non-volatile resistance random access memory(RRAM) devices based on ferroelectric materials.展开更多
Monolithic ZrB2,W coatings and ZrB2/W multilayers with different modulation periods and modulation ratios were synthesized by ion beam assisted deposition at room temperature and 400°C.X-ray diffraction (XRD),sca...Monolithic ZrB2,W coatings and ZrB2/W multilayers with different modulation periods and modulation ratios were synthesized by ion beam assisted deposition at room temperature and 400°C.X-ray diffraction (XRD),scanning electron microscopy (SEM),surface profiler,and nanoindention were employed to investigate the influences of the deposition temperature and the modulation period on the growth,textures,interface structure,and mechanical properties of the multilayers.The results indicated that the multilayer with modulation period of 13 nm synthesized at room temperature possessed a higher hardness of 23.8 GPa.Deposition temperature gave a significant contribution to mechanical property enhancement.The 400°C-deposition temperature led to a maximum hardness and elastic modulus value of 32.1 and 399.1 GPa for ZrB2/W multilayer with a modulation period of 6.7 nm.Its critical load increased to 42.8 mN and residual stress decreased to -0.7 GPa.A higher deposition temperature can cause an increase in interfacial atomic mixture and mobility of surface species,which induceds an increase in areal atomic density and dislocation pinning.These results as well as small nanoscale grain sizes should be related to hardness increase.展开更多
ZrB2/ZrAlN multilayered coatings with various modulation ratios(t ZrB2:t ZrAlN)and constant modulation periods were prepared by magnetron sputtering system at room temperature.SEM,XRD,surface profiler and nano-indente...ZrB2/ZrAlN multilayered coatings with various modulation ratios(t ZrB2:t ZrAlN)and constant modulation periods were prepared by magnetron sputtering system at room temperature.SEM,XRD,surface profiler and nano-indenter were employed to investigate the influences of tZ rB 2:tZrAlNon the microstructure and mechanical properties of the coatings.Sharp interfaces and nanoscale multilayered modulation were confirmed by SEM.The multilayer with modulation period of 40 nm and ratio of 3:1 displayed the highest hardness(36.4 GPa)and critical fracture load(76.477 mN)with lower stress.The polycrystalline structure and multilayered modulate structure were directly responsible for the enhanced mechanical properties.展开更多
文摘Zinc and Zn-Ni alloy compositionally modulated multilayer （CMM） coatings were electrodeposited on to a steel substrate by the successive deposition of zinc and Zn-Ni alloy sublayers from dual baths. The coated samples were evaluated in terms of the surface appearance, surface and cross-sectional morphologies, as well as corrosion resistance. The microstructural characteristics that were examined using the field emission gun scanning electron microscopy （FEGSEM） confirmed the layered structure, grain refinement of the zinc and Zn-Ni alloy CMM coatings, and revealed the existence of microcracks caused by the internal stress in the thick Zn-Ni alloy sublayers. The corrosion resistance that was evaluated by means of the salt spray test shows that the zinc and Zn-Ni alloy CMM coatings were more corrosion-resistant than the monolithic coatings of zinc or Zn-Ni alloy of the same thickness. The possible reasons for the better protective performance of Zn-Ni/Zn CMM coatings were given on the basis of the analysis on the micrographic features of zinc and Zn-Ni alloy CMM eoatings after the corrosion test. A probable corrosion mechanism of zinc and Zn-Ni alloy CMM coatings was also proposed.
基金Funded by the Natural Science Foundation of Shaanxi Province(2005B-22)
文摘Varieties of zinc and Zn-Co alloy compositionally modulated multilayer （CMM） coatings were electrodeposited onto steel substrates using dual bath technique. The surface and cross-sectional morphologies of coated samples were examined using scanning electron microscopy （ SEM ）. The existence of iuternal stress in ZnCo alloy deposits was confirmed by the cross-sectional morphalogies for the occurrence of micro-cracks in the thick Zn-Co alloy deposit alone. The corrosion performance was evaluated using neutral salt spray testing, corrosion potential measurement and anodic polarization methods. The experimental results slum, that the zinc and Zn- Co alloy CMM coatings were more corrosion-resistant than the monolithic coatings of zinc or Zn-Co alloy alone with a similar thickness. The analysis on the micrographic features of zinc and Zn-Co alloy CMM coatings, using field emission gun scanning electron microscopy （FEGSEM） after corrosion testing, explains the probable reusons why the Zn-Co/ Zn CMM coating system has a better protective performance.
文摘The effects of pulse parameters on the cobalt content, surface morphologies and grain size of Zn-Co alloy deposits were studied using a pulse plating technique with a square-wave current containing reverse pulse. Average current density and reverse anodic current density amongst the variables investigated have very strong effects on the cobalt content in the Zn-Co alloy deposits. Grain size, surface appearance and internal stress in the deposit were improved significantly by introducing the reverse current. Varieties of Zn-Co alloy compositionally modulated multilayer (CMM) coatings with large differences in cobalt contents for different sublayers were electrodeposited by designing corresponding waveforms using a computer-aided pulse plater and characterized in terms of surface morphologies. Cross-sectional morphologies of the Zn-Co alloy CMM coatings, examined using field emission gun scanning electron microscopy (FEGSEM), confirmed the layered structure.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61575076 and 61804148)the National Key Research and Development Plan of China(Grant No.2016YFB0402502)
文摘The extinction ratio and insertion loss of spatial light modulator are subject to the material problem, thus limiting its applications. One reflection-type silicon-based spatial light modulator with high reflective materials outside the Fabry-Perot cavity is demonstrated in this paper. The reflectivity values of the outside-cavity materials with different film layer numbers are simulated. The reflectivity values of 6-pair Ta2O5/SiO2 films at 1550 nm are experimentally verified to be as high as 99.9%. The surfaces of 6-pair Ta2O5/SiO2 films are smooth: their root-mean-square roughness values are as small as 0.53 nm. The insertion loss of the device at 1550 nm is only 1.2 dB. The high extinction ratio of the device at 1550 nm and 11 V is achieved to be 29.7 dB. The spatial light modulator has a high extinction ratio and low insertion loss for applications.
文摘Zinc and Zn-Ni alloy compositionally modulated multilayer （CMM） coatings were electrodeposited from dual baths. The coated samples were evaluated in terms of surface appearance, surface and cross-sectional morphologies, as well as corrosion resistance. The results obtained from the salt spray test show that the zinc and Zn-Ni alloy CMM coatings are more corrosion-resistant than the monolithic coatings of zinc or Zn-Ni alloy alone with a similar thickness. The corrosion potential measurement and anodic polarisation tests were undertaken to examine the probable corrosion mechanisms of zinc and Zn-Ni alloy CMM coatings. Analysis on the micrographic features of zinc and Zn-Ni alloy CMM coatings after the corrosion test explains the probable reasons why the Zn-Ni/Zn CMM coatings have a better protective performance. Surface morphologies and compositional analysis of the remaining coating material of Zn-Ni alloy deposit after the corrosion test confirms the dezincification mechanism of the Zn-Ni alloy deposit during the corrosion process.
基金supported by the National Natural Science Foundation of China(Nos.51522106 and 51375475)Zhejiang Key Research and Development Program(2017C01001)Public Projects of Zhejiang Province
文摘In this paper, graphite-like carbon （GLC） films with Cr buffer layer were fabricated by DC magnetron sputtering technique with the thickness ratio of Cr to GLC films varying from 1：2 to 1：20. The effect of Cr]GLC modulation ratio on microstructure, mechanical and tribological properties in artificial seawater was mainly investigated by scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, nano-indenter and a reciprocating sliding tribo-meter. The propagation of defects plays an important role in the evolution of delamination, which is critical to wear failure of GLC films in artificial seawa- ter. Designing the proper multilayer structure could inhibit the defects propagation and thus protect the basis material. The multilayer Cr/GLC film with optimized ratio of 1：3 demonstrates a low average friction coefficient of 0.08 ± 0.006 and wear rate of （2.3 ± 0.3） × 10^-8 mm3/（N m） in artificial seawater, respectively.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51801133,51505318,and 51671140)the Science and Technology Major Project of Shanxi Province,China(Grant No.20181102013)+1 种基金the Shanxi Provincial Youth Fund,China(Grant No.201801D221135)the“1331 Project”Engineering Research Center of Shanxi Province,China(Grant No.PT201801).
文摘Si/a-C:H(Ag)multilayer films with different modulation periods are prepared to test their potential applications in human body.The composition,microstructure,mechanical and tribological properties in the simulated body fluid are investigated.The results show the concentration of Ag first decreases and then increases with the modulation period decreasing from 984 nm to 250 nm.Whereas the C content has an opposite variation trend.Notably,the concentration of Ag plays a more important role than the modulation period in the properties of the multilayer film.The a-C:H sublayer of the film with an appropriate Ag concentration(8.97 at.%)(modulation period of 512 nm)maintains the highest sp3/sp2 ratio,surface roughness and hardness,and excellent tribological property in the stimulated body fluid.An appropriate number of Ag atoms and size of Ag atom allow the Ag atoms to easily enter into the contact interface for load bearing and lubricating.This work proves that the Ag nanoparticles in the a-C:H sublayer plays a more important role in the tribological properties of the composite-multilayer film in stimulated body fluid condition.
基金Project supported by the Scientific Research Program of Hunan Provincial Education Department,China(Grant No.18C0232)the International Cooperative Extension Program of Changsha University of Science and Technology,China(Grant No.2019IC35)
文摘The novel BaTiO3/BiFeO3/TiO2 multilayer heterojunction is prepared on a fluorine-doped tinoxide(FTO) substrate by the sol–gel method. The results indicate that the Pt/Ba TiO3/BiFeO3/TiO2/FTO heterojunction exhibits stable bipolar resistive switching characteristic, good retention performance, and reversal characteristic. Under different pulse voltages and light fields, four stable resistance states can also be realized. The analysis shows that the main conduction mechanism of the resistive switching characteristic of the heterojunction is space charge limited current(SCLC) effect. After the comprehensive analysis of the band diagram and the P–E ferroelectric property of the multilayer heterojunction, we can deduce that the SCLC is formed by the effect of the oxygen vacancy which is controlled by ferroelectric polarizationmodulated change of interfacial barrier. And the effective photo-generated carrier also plays a regulatory role in resistance state(RS), which is formed by the double ferroelectric layer Ba TiO3/BiFeO3 under different light fields. This research is of potential application values for developing the multi-state non-volatile resistance random access memory(RRAM) devices based on ferroelectric materials.
基金supported by the National Natural Science Foundation of China (Grant No. 50872094, 50872093) the Key Project of Applied Basic and Advanced Technology Research Plan of Tianjin "Design and synthesis of superhard nanomulitilayers with boride layers" (2011)
文摘Monolithic ZrB2,W coatings and ZrB2/W multilayers with different modulation periods and modulation ratios were synthesized by ion beam assisted deposition at room temperature and 400°C.X-ray diffraction (XRD),scanning electron microscopy (SEM),surface profiler,and nanoindention were employed to investigate the influences of the deposition temperature and the modulation period on the growth,textures,interface structure,and mechanical properties of the multilayers.The results indicated that the multilayer with modulation period of 13 nm synthesized at room temperature possessed a higher hardness of 23.8 GPa.Deposition temperature gave a significant contribution to mechanical property enhancement.The 400°C-deposition temperature led to a maximum hardness and elastic modulus value of 32.1 and 399.1 GPa for ZrB2/W multilayer with a modulation period of 6.7 nm.Its critical load increased to 42.8 mN and residual stress decreased to -0.7 GPa.A higher deposition temperature can cause an increase in interfacial atomic mixture and mobility of surface species,which induceds an increase in areal atomic density and dislocation pinning.These results as well as small nanoscale grain sizes should be related to hardness increase.
基金supported by the National Natural Science Foundation of China(Grant No.50872094)the International Collaboration Project of Tianjin Science and Technology Plan(Grant No.07ZCGHHZ01500)Key Project of Applied Basic and Advanced Technology Research Plan of Tianjin"Design and Synthesis of Superhard"Nanomuliti Layers with Boride Layers(2010)
文摘ZrB2/ZrAlN multilayered coatings with various modulation ratios(t ZrB2:t ZrAlN)and constant modulation periods were prepared by magnetron sputtering system at room temperature.SEM,XRD,surface profiler and nano-indenter were employed to investigate the influences of tZ rB 2:tZrAlNon the microstructure and mechanical properties of the coatings.Sharp interfaces and nanoscale multilayered modulation were confirmed by SEM.The multilayer with modulation period of 40 nm and ratio of 3:1 displayed the highest hardness(36.4 GPa)and critical fracture load(76.477 mN)with lower stress.The polycrystalline structure and multilayered modulate structure were directly responsible for the enhanced mechanical properties.
