The TiAl-based alloys sheet with 150 mm×100 mm×0.4 mm and the TiAl/Nb laminated composites with 150 mm×100 mm×0.2 mm were fabricated by using electron beam-physical vapor deposition(EB-PVD) method,...The TiAl-based alloys sheet with 150 mm×100 mm×0.4 mm and the TiAl/Nb laminated composites with 150 mm×100 mm×0.2 mm were fabricated by using electron beam-physical vapor deposition(EB-PVD) method, respectively. The microstructure and properties of the sheet were investigated by AFM, SEM and EDS. The results show that the TiAl based alloys sheet has a good surface quality, and its microstructure is columnar crystal. The component of the alloys indicates a regular and periodical gradient change which leads to the spontaneous delamination along the normal direction of substrate. In the TiAl/Nb laminated composites alternating overlaid by TiAl of 24 layers and Nb of 23 layers, the interface of each layer evenly distributed throughout the cross-section is transparent, and the interlayer spacing is about 8μm. The component of TiAl layers also changes regularly along the normal direction of substrate, but no delamination phenomenon is found. The TiAl/Nb laminated composites have better ductility than the TiAl-based alloys sheet.展开更多
Laminates with alternating layers of NiCoCrAlY and NiCr were fabricated by using electron beam physical vapor deposition (EB-PVD) method. The influence of the substrate temperature on morphology of the laminates was i...Laminates with alternating layers of NiCoCrAlY and NiCr were fabricated by using electron beam physical vapor deposition (EB-PVD) method. The influence of the substrate temperature on morphology of the laminates was investigated. The results show that in order to produce NiCoCrAlY/NiCr laminates with lower porosity, higher substrate temperature is required. The mechanical properties of the as-deposited samples and heat-treated samples were examined using tensile tests. The stress-strain curve of the as-deposited laminate shows a typical characteristic of multilayered materials and the fracture behavior is improved by annealing the samples at high temperatures. The tensile strength of the samples annealed at 760℃ is 658.4MPa, and the elongation reaches 6.2%.展开更多
By using physical vapor deposition(PVD)to grow metallic nanorods,the characteristic length is controllable,which can be identified by two different growth modes:Mode I and Mode II.In Mode I,the growth of metallic nano...By using physical vapor deposition(PVD)to grow metallic nanorods,the characteristic length is controllable,which can be identified by two different growth modes:Mode I and Mode II.In Mode I,the growth of metallic nanorods is dominated by the monolayer surface steps.Whereas in Mode II,the growth mechanism is mainly determined by the multilayer surface steps.In this work,we focused on the analysis of the physical process of Mode I,in which the adatoms diffuse on the monolayer surface at beginning,then diffuse down to the next monolayer surface,and finally result in the metallic nanorods growth.Based on the physical process,both the variations of the characteristic length and the numerical solutions were theoretically proposed.In addition,the twodimensional(2 D)lattice kinetic Monte Carlo simulations were employed to verify the theoretical derivation of the metallic nanorods growth.Our results pay a new way for modifying the performance of metallic nanorods-based applications and devices.展开更多
A two-dimensional Kinetic Monte Carlo method has been developed for simulating the physical vapor deposition of thin Cu films on Cu substrate. An improved embedded atom method was used to calculate the interatomic pot...A two-dimensional Kinetic Monte Carlo method has been developed for simulating the physical vapor deposition of thin Cu films on Cu substrate. An improved embedded atom method was used to calculate the interatomic potential and determine the diffusion barrier energy and residence time. Parameters, including incident angle,deposition rate and substrate temperature, were investigated and discussed in order to find their influences on the thin film morphology.展开更多
Ti-Al thin sheet with dimension of 450 mm×450 mm×0.2 mm was prepared by electron beam physical vapor deposition(EB-PVD) technology. The surface and cross-section pattern of as-deposited sample were studied b...Ti-Al thin sheet with dimension of 450 mm×450 mm×0.2 mm was prepared by electron beam physical vapor deposition(EB-PVD) technology. The surface and cross-section pattern of as-deposited sample were studied by SEM and AFM,and then the composition and phase were analysed by XRD and EPMA. Finally,the effect on deposit by re-evaporation of Al was explored by calculating the ratio of re-evaporating capacity with depositing capacity of Al on the substrate. The results indicate that the evaporation process with Nb addition into the molten pool makes it earlier to reach the steady-state. The existing equiaxed crystal and columnar crystal along the cross-sectional may be caused by the transformation latent heat released during the transition course of atoms from gaseous state to solid state. The effect on deposit by re-evaporation of Al can be neglected because the re-evaporating capacity of Al is far below that of the depositing capacity.展开更多
Zinc alloy coating attracted much attention due to its high anti-corrosive properties.Particularly,zinc alloy coatings containing magnesium was considered a promising metallic alloy due to a remarkable improvement of ...Zinc alloy coating attracted much attention due to its high anti-corrosive properties.Particularly,zinc alloy coatings containing magnesium was considered a promising metallic alloy due to a remarkable improvement of corrosion resistance.The proper magnesium content for Zn-Mg alloy coatings was studied.The samples were prepared using thermal evaporation method.The influence of Zn-Mg alloy coating on corrosion resistance was evaluated using immersion test,potentiodynamic test,and galvanic test in 3% NaCl solution at room temperature.The results show that the corrosion resistance of Zn-Mg alloy coatings is strongly dependent on magnesium content.Corrosion potential decreases with increasing magnesium content,whereas current density increases up to 15% magnesium content,and passivity region was found only in Zn-Mg coatings.展开更多
The coatings of W-Ti carbides on the surface of diamond was obtained by using physical vapor deposition (PVD), during which WO3 powders pre-treated with hydrofluoric acid were reduced by titanium hydride in vacuum at ...The coatings of W-Ti carbides on the surface of diamond was obtained by using physical vapor deposition (PVD), during which WO3 powders pre-treated with hydrofluoric acid were reduced by titanium hydride in vacuum at 850 ℃. The resistance of diamond to corrosion at high-temperature was investigated. The formation of W-Ti carbides on the surface of diamond was verified by X-ray diffraction analysis, the interface state between diamond and matrix in metaLbase diamond composite was observed by scanning electron microscope. The results showed that the carbide coating is easy to be formed at low deposition temperature on the surface of diamond, while the resistance of diamond to corrosion at highutemperature and the strength of bonding between diarnond and metal matrix are effectively improved.展开更多
ZrN/TiZrN multilayers are deposited by using the cathodic vacuum arc method with different substrate bias（from 0 to 800 V）,using Ti and Zr plasma flows in residual N 2 atmosphere,combined with ion bombardment of sam...ZrN/TiZrN multilayers are deposited by using the cathodic vacuum arc method with different substrate bias（from 0 to 800 V）,using Ti and Zr plasma flows in residual N 2 atmosphere,combined with ion bombardment of sample surfaces.The effect of pulsed bias on the structure and properties of films is investigated.Microstructure of the coating is analyzed by X-ray diffraction（XRD）,and scanning electron microscopy（SEM）.In addition,nanohardness,Young＇s modulus,and scratch tests are performed.The experimental results show that the films exhibit a nanoscale multilayer structure consisting of TiZrN and ZrN phases.Solid solutions are formed for component TiZrN films.The dominant preferred orientation of TiZrN films is（111） and（220）.At a pulsed bias of 200 V,the nanohardness and the adhesion strength of the ZrN/TiZrN multilayer reach a maximum of 38 GPa,and 78 N,respectively.The ZrN/TiZrN multilayer demonstrates an enhanced nanohardness compared with binary TiN and ZrN films deposited under equivalent conditions.展开更多
Over the past years, great achievements have been made in the development of coating technologies for surface improvement of aluminum alloys. Despite these achievements, the role in the market strongly depends on the ...Over the past years, great achievements have been made in the development of coating technologies for surface improvement of aluminum alloys. Despite these achievements, the role in the market strongly depends on the ability of surface coating technology under technical and economic considerations to meet the increased demands for heavy tribological applications of aluminum alloys. Microplasma oxidation (MPO) technology has recently been studied as a novel and effective means to provide thick and hard ceramic coating with improved properties such as excellent load-bearing and wear resistance properties on aluminum alloys. The present work covers the evaluation of the performances of current single and duplex coatings combining MPO, physical vapor deposition (PVD), and plasma assisted chemical vapor deposition (PACVD) coatings on aluminum alloys. It suggests that the MPO coating is a promising candidate for design engineers to apply aluminum alloys to heavy load-bearing applications. The prospective future for the research on MPO coatings is introduced as well.展开更多
AlN thin films were deposited on c-,a-and r-plane sapphire substrates by the magnetron sputtering technique.The in-fluence of high-temperature thermal annealing(HTTA)on the structural,optical properties as well as sur...AlN thin films were deposited on c-,a-and r-plane sapphire substrates by the magnetron sputtering technique.The in-fluence of high-temperature thermal annealing(HTTA)on the structural,optical properties as well as surface stoichiometry were comprehensively investigated.The significant narrowing of the(0002)diffraction peak to as low as 68 arcsec of AlN after HTTA implies a reduction of tilt component inside the AlN thin films,and consequently much-reduced dislocation densities.This is also supported by the appearance of E2(high)Raman peak and better Al-N stoichiometry after HTTA.Furthermore,the in-creased absorption edge after HTTA suggests a reduction of point defects acting as the absorption centers.It is concluded that HTTA is a universal post-treatment technique in improving the crystalline quality of sputtered AlN regardless of sapphire orienta-tion.展开更多
Cathodic arc evaporation is a well-established physical vapor deposition technique which is characterized by a high degree of ionization and high deposition rate. So far, this technique has been mainly used for the de...Cathodic arc evaporation is a well-established physical vapor deposition technique which is characterized by a high degree of ionization and high deposition rate. So far, this technique has been mainly used for the deposition of tribological coatings. In this study, anti-corrosive and electrical conductive carbon-based coatings with a metallic interlayer were prepared on stainless steel substrates as surface modification for metallic bipolar plates. Hereby, the influence of the deposition temperature during the deposition of the carbon top layer was investigated. Raman spectroscopy revealed differences in the microstructure at 200°C compared to 300°C and 100°C. Measurements of the interfacial contact resistance showed that the deposited coatings significantly improve the electrical conductivity. There are only minor differences between the different carbon top layers. The corrosion resistance of the coatings was studied via potentiodynamic polarization at room temperature and 80°C. Experiments showed that the coating with a carbon top layer deposited at 200°C, considerably reduces the current density and thus corrosion of the substrate is suppressed.展开更多
An extended one-dimensional stress model for the deposition of multilayer films is built based on the existing stress model by considering the influence of deposition conditions. Both thermal stress and intrinsic stre...An extended one-dimensional stress model for the deposition of multilayer films is built based on the existing stress model by considering the influence of deposition conditions. Both thermal stress and intrinsic stress are considered to constitute the final residual stress in the model. The deposition process conditions such as deposition temperature, oxygen pressure, and film growth rate are correlated to the full stress model to analyze the final residual stress distribution, and thus the deformation of the deposited multilayer system under different process conditions. Also, the model is numerically realized with in-house built code. A deposition of Ag-Cu multilayer system is simulated with the as-built extended stress model, and the final residual stresses under different deposition conditions are discussed with part of the results compared with experiment from other literature.展开更多
The NiCoCrAl alloy sheet was fabricated by electron beam physical vapor deposition technique and the effects of the heat treatment on the microstructure and tensile strength of the NiCoCrAl alloy sheet were investigat...The NiCoCrAl alloy sheet was fabricated by electron beam physical vapor deposition technique and the effects of the heat treatment on the microstructure and tensile strength of the NiCoCrAl alloy sheet were investigated. The heat treatment at 1050 °C is favorable to improve the interface bonding between the columnar structures due to the disappearance of the intergranular gaps. Comparing with the thin NiCoCrAl alloy sheet before heat treatment, the Ni3Al phase appears in the NiCoCrAl alloy sheet after heat treatment, which is favorable to improve the interface bonding between the columnar structures. The increase in the tensile strength and elongation is attributed to the improvement of the interface bonding between the columnar structures. The residual stress in the NiCoCrAl alloy sheet after heat treatment is reduced significantly, which also confirms that the interface bonding is improved by the heat treatment.展开更多
基金Projects(90205034, 90405016) supported by the National Natural Science Foundation of China
文摘The TiAl-based alloys sheet with 150 mm×100 mm×0.4 mm and the TiAl/Nb laminated composites with 150 mm×100 mm×0.2 mm were fabricated by using electron beam-physical vapor deposition(EB-PVD) method, respectively. The microstructure and properties of the sheet were investigated by AFM, SEM and EDS. The results show that the TiAl based alloys sheet has a good surface quality, and its microstructure is columnar crystal. The component of the alloys indicates a regular and periodical gradient change which leads to the spontaneous delamination along the normal direction of substrate. In the TiAl/Nb laminated composites alternating overlaid by TiAl of 24 layers and Nb of 23 layers, the interface of each layer evenly distributed throughout the cross-section is transparent, and the interlayer spacing is about 8μm. The component of TiAl layers also changes regularly along the normal direction of substrate, but no delamination phenomenon is found. The TiAl/Nb laminated composites have better ductility than the TiAl-based alloys sheet.
文摘Laminates with alternating layers of NiCoCrAlY and NiCr were fabricated by using electron beam physical vapor deposition (EB-PVD) method. The influence of the substrate temperature on morphology of the laminates was investigated. The results show that in order to produce NiCoCrAlY/NiCr laminates with lower porosity, higher substrate temperature is required. The mechanical properties of the as-deposited samples and heat-treated samples were examined using tensile tests. The stress-strain curve of the as-deposited laminate shows a typical characteristic of multilayered materials and the fracture behavior is improved by annealing the samples at high temperatures. The tensile strength of the samples annealed at 760℃ is 658.4MPa, and the elongation reaches 6.2%.
文摘By using physical vapor deposition(PVD)to grow metallic nanorods,the characteristic length is controllable,which can be identified by two different growth modes:Mode I and Mode II.In Mode I,the growth of metallic nanorods is dominated by the monolayer surface steps.Whereas in Mode II,the growth mechanism is mainly determined by the multilayer surface steps.In this work,we focused on the analysis of the physical process of Mode I,in which the adatoms diffuse on the monolayer surface at beginning,then diffuse down to the next monolayer surface,and finally result in the metallic nanorods growth.Based on the physical process,both the variations of the characteristic length and the numerical solutions were theoretically proposed.In addition,the twodimensional(2 D)lattice kinetic Monte Carlo simulations were employed to verify the theoretical derivation of the metallic nanorods growth.Our results pay a new way for modifying the performance of metallic nanorods-based applications and devices.
文摘A two-dimensional Kinetic Monte Carlo method has been developed for simulating the physical vapor deposition of thin Cu films on Cu substrate. An improved embedded atom method was used to calculate the interatomic potential and determine the diffusion barrier energy and residence time. Parameters, including incident angle,deposition rate and substrate temperature, were investigated and discussed in order to find their influences on the thin film morphology.
基金Project(NCET2004) supported by the Program for New Century Excellent Talents in University, China
文摘Ti-Al thin sheet with dimension of 450 mm×450 mm×0.2 mm was prepared by electron beam physical vapor deposition(EB-PVD) technology. The surface and cross-section pattern of as-deposited sample were studied by SEM and AFM,and then the composition and phase were analysed by XRD and EPMA. Finally,the effect on deposit by re-evaporation of Al was explored by calculating the ratio of re-evaporating capacity with depositing capacity of Al on the substrate. The results indicate that the evaporation process with Nb addition into the molten pool makes it earlier to reach the steady-state. The existing equiaxed crystal and columnar crystal along the cross-sectional may be caused by the transformation latent heat released during the transition course of atoms from gaseous state to solid state. The effect on deposit by re-evaporation of Al can be neglected because the re-evaporating capacity of Al is far below that of the depositing capacity.
基金supported by the Smart Coating Steel Development Center,World Premier Materials (WPM) Program of the Ministry of Knowledge Economy of Korea and Korea Maritime University
文摘Zinc alloy coating attracted much attention due to its high anti-corrosive properties.Particularly,zinc alloy coatings containing magnesium was considered a promising metallic alloy due to a remarkable improvement of corrosion resistance.The proper magnesium content for Zn-Mg alloy coatings was studied.The samples were prepared using thermal evaporation method.The influence of Zn-Mg alloy coating on corrosion resistance was evaluated using immersion test,potentiodynamic test,and galvanic test in 3% NaCl solution at room temperature.The results show that the corrosion resistance of Zn-Mg alloy coatings is strongly dependent on magnesium content.Corrosion potential decreases with increasing magnesium content,whereas current density increases up to 15% magnesium content,and passivity region was found only in Zn-Mg coatings.
文摘The coatings of W-Ti carbides on the surface of diamond was obtained by using physical vapor deposition (PVD), during which WO3 powders pre-treated with hydrofluoric acid were reduced by titanium hydride in vacuum at 850 ℃. The resistance of diamond to corrosion at high-temperature was investigated. The formation of W-Ti carbides on the surface of diamond was verified by X-ray diffraction analysis, the interface state between diamond and matrix in metaLbase diamond composite was observed by scanning electron microscope. The results showed that the carbide coating is easy to be formed at low deposition temperature on the surface of diamond, while the resistance of diamond to corrosion at highutemperature and the strength of bonding between diarnond and metal matrix are effectively improved.
基金Project supported by the National Magnetic Confinement Fusion Science Program of China (Grant No. 2009GB106004)
文摘ZrN/TiZrN multilayers are deposited by using the cathodic vacuum arc method with different substrate bias（from 0 to 800 V）,using Ti and Zr plasma flows in residual N 2 atmosphere,combined with ion bombardment of sample surfaces.The effect of pulsed bias on the structure and properties of films is investigated.Microstructure of the coating is analyzed by X-ray diffraction（XRD）,and scanning electron microscopy（SEM）.In addition,nanohardness,Young＇s modulus,and scratch tests are performed.The experimental results show that the films exhibit a nanoscale multilayer structure consisting of TiZrN and ZrN phases.Solid solutions are formed for component TiZrN films.The dominant preferred orientation of TiZrN films is（111） and（220）.At a pulsed bias of 200 V,the nanohardness and the adhesion strength of the ZrN/TiZrN multilayer reach a maximum of 38 GPa,and 78 N,respectively.The ZrN/TiZrN multilayer demonstrates an enhanced nanohardness compared with binary TiN and ZrN films deposited under equivalent conditions.
文摘Over the past years, great achievements have been made in the development of coating technologies for surface improvement of aluminum alloys. Despite these achievements, the role in the market strongly depends on the ability of surface coating technology under technical and economic considerations to meet the increased demands for heavy tribological applications of aluminum alloys. Microplasma oxidation (MPO) technology has recently been studied as a novel and effective means to provide thick and hard ceramic coating with improved properties such as excellent load-bearing and wear resistance properties on aluminum alloys. The present work covers the evaluation of the performances of current single and duplex coatings combining MPO, physical vapor deposition (PVD), and plasma assisted chemical vapor deposition (PACVD) coatings on aluminum alloys. It suggests that the MPO coating is a promising candidate for design engineers to apply aluminum alloys to heavy load-bearing applications. The prospective future for the research on MPO coatings is introduced as well.
基金supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2020298)National Key Scientific Instrument and Equipment Development Projects of China(YJKYYQ20190074)+2 种基金National Natural Science Foundation of China(61974149)Primary Research and Development Plan of Zhejiang Province(2020C01145)the Natural Science Foundation of Zhejiang Province(LQ21F040004)。
文摘AlN thin films were deposited on c-,a-and r-plane sapphire substrates by the magnetron sputtering technique.The in-fluence of high-temperature thermal annealing(HTTA)on the structural,optical properties as well as surface stoichiometry were comprehensively investigated.The significant narrowing of the(0002)diffraction peak to as low as 68 arcsec of AlN after HTTA implies a reduction of tilt component inside the AlN thin films,and consequently much-reduced dislocation densities.This is also supported by the appearance of E2(high)Raman peak and better Al-N stoichiometry after HTTA.Furthermore,the in-creased absorption edge after HTTA suggests a reduction of point defects acting as the absorption centers.It is concluded that HTTA is a universal post-treatment technique in improving the crystalline quality of sputtered AlN regardless of sapphire orienta-tion.
文摘Cathodic arc evaporation is a well-established physical vapor deposition technique which is characterized by a high degree of ionization and high deposition rate. So far, this technique has been mainly used for the deposition of tribological coatings. In this study, anti-corrosive and electrical conductive carbon-based coatings with a metallic interlayer were prepared on stainless steel substrates as surface modification for metallic bipolar plates. Hereby, the influence of the deposition temperature during the deposition of the carbon top layer was investigated. Raman spectroscopy revealed differences in the microstructure at 200°C compared to 300°C and 100°C. Measurements of the interfacial contact resistance showed that the deposited coatings significantly improve the electrical conductivity. There are only minor differences between the different carbon top layers. The corrosion resistance of the coatings was studied via potentiodynamic polarization at room temperature and 80°C. Experiments showed that the coating with a carbon top layer deposited at 200°C, considerably reduces the current density and thus corrosion of the substrate is suppressed.
基金supported by the National Natural Science Foundation of China(Grant Nos.51076075,91224008 and 91024032)
文摘An extended one-dimensional stress model for the deposition of multilayer films is built based on the existing stress model by considering the influence of deposition conditions. Both thermal stress and intrinsic stress are considered to constitute the final residual stress in the model. The deposition process conditions such as deposition temperature, oxygen pressure, and film growth rate are correlated to the full stress model to analyze the final residual stress distribution, and thus the deformation of the deposited multilayer system under different process conditions. Also, the model is numerically realized with in-house built code. A deposition of Ag-Cu multilayer system is simulated with the as-built extended stress model, and the final residual stresses under different deposition conditions are discussed with part of the results compared with experiment from other literature.
基金Projects(51002019,91016024,51102031)supported by the National Natural Science Foundation of China
文摘The NiCoCrAl alloy sheet was fabricated by electron beam physical vapor deposition technique and the effects of the heat treatment on the microstructure and tensile strength of the NiCoCrAl alloy sheet were investigated. The heat treatment at 1050 °C is favorable to improve the interface bonding between the columnar structures due to the disappearance of the intergranular gaps. Comparing with the thin NiCoCrAl alloy sheet before heat treatment, the Ni3Al phase appears in the NiCoCrAl alloy sheet after heat treatment, which is favorable to improve the interface bonding between the columnar structures. The increase in the tensile strength and elongation is attributed to the improvement of the interface bonding between the columnar structures. The residual stress in the NiCoCrAl alloy sheet after heat treatment is reduced significantly, which also confirms that the interface bonding is improved by the heat treatment.
