Potential engineering applications of magnesium(Mg)and Mg-based alloys,as the lightest structural metal,have made them a popular subject of study.However,the inferior corrosion and wear characteristics significantly l...Potential engineering applications of magnesium(Mg)and Mg-based alloys,as the lightest structural metal,have made them a popular subject of study.However,the inferior corrosion and wear characteristics significantly limit their application range.It is widely recognized that surface treatment is the most commonly utilized technique for remarkably improving a substrate’s surface characteristics.Numerous methods have been introduced for the surface treatment of Mg and Mg-based alloys to improve their corrosion behavior and tribological performance.Among these,thermal spray(TS)technology provides several methods for deposition of various functional metallic,ceramic,cermet,or other coatings tailored to particular conditions.Recent researches have shown the tremendous potential for thermal spray coated Mg alloys for biomedical and industrial applications.In this context,the cold spray(CS)method,as a comparatively new TS coating technique,can generate the coating layer using kinetic energy rather than combined thermal and kinetic energies,like the high-velocity oxy-fuel(HVOF)spray method.Moreover,the CS process,as a revolutionary method,is able to repair and refurbish with a faster turnaround time;it also provides solutions that do not require dealing with the thermal stresses that are part of the other repair processes,such as welding or other TS processes using a high-temperature flame.In this review paper,the recently designed coatings that are specifically applied to Mg alloys(primarily for industrial applications)employing various coating processes are reviewed.Because of the increased utilization of CS technology for both 3D printed(additively manufactured)coatings and repair of structurally critical components,the most recent CS methods for the surface treatment,repair,and refurbishment of Mg alloys as well as their benefits and restrictions are then discussed and reviewed in detail.Lastly,the prospects of this field of study are briefly discussed,along with a summary of the presented work.展开更多
This study investigates the effect of graphene oxide(GO)on the mechanical and corrosion behavior,antibacterial performance,and cell response of Mg–Zn–Mn(MZM)nanocomposite.MZM/GO nanocomposites with different amounts...This study investigates the effect of graphene oxide(GO)on the mechanical and corrosion behavior,antibacterial performance,and cell response of Mg–Zn–Mn(MZM)nanocomposite.MZM/GO nanocomposites with different amounts of GO(i.e.,0.5 wt%,1.0 wt%,and1.5 wt%)were fabricated by the semi-powder metallurgy method.The influence of GO on the MZM nanocomposite was analyzed through the hardness,compressive,corrosion,antibacterial,and cytotoxicity tests.The experimental results showed that,with the increase in the amount of GO(0.5 wt%and 1.5 wt%),the hardness value,compressive strength,and antibacterial performance of the MZM nanocomposite increased,whereas the cell viability and osteogenesis level decreased after the addition of 1.5 wt%GO.Moreover,the electrochemical examination results showed that the corrosion behavior of the MZM alloy was significantly enhanced after encapsulation in 0.5 wt%GO.In summary,MZM nanocomposites reinforced with GO can be used for implant applications because of their antibacterial performance and mechanical property.展开更多
The increasing demand for energy absorbent structures,paired with the need for more efficient use of materials in a wide range of engineering fields,has led to an extensive range of designs in the porous forms of sand...The increasing demand for energy absorbent structures,paired with the need for more efficient use of materials in a wide range of engineering fields,has led to an extensive range of designs in the porous forms of sandwiches,honeycomb,and foams.To achieve an even better performance,an ingenious solution is to learn how biological structures adjust their configurations to absorb energy without catastrophic failure.In this study,we have attempted to blend the shape freedom,offered by additive manufacturing techniques,with the biomimetic approach,to propose new lattice structures for energy absorbent applications.To this aim we have combined multiple bio-inspirational sources for the design of optimized configurations under compressive loads.Periodic lattice structures are fabricated based on the designed unit cell geometries and studied using experimental and computational strategies.The individual effect of each bio-inspired feature has been evaluated on the energy absorbance performance of the designed structure.Based on the design parameters of the lattices,a tuning between the strength and energy absorption could be obtained,paving the way for transition within a wide range of real-life applicative scenarios.展开更多
Magnesium alloys have been widely studied as materials for temporary implants,but their use has been limited by their corrosion rate.Recently,coatings have been proven to provide an effective barrier.Though only littl...Magnesium alloys have been widely studied as materials for temporary implants,but their use has been limited by their corrosion rate.Recently,coatings have been proven to provide an effective barrier.Though only little explored in the field,Atomic Layer Deposition(ALD)stands out as a coating technology due to the outstanding film conformality and density achievable.Here,we provide first insights into the corrosion behavior and the induced biological response of 100 nm thick ALD TiO_(2),HfO_(2)and ZrO_(2)coatings on AZ31 alloy by means of potentiodynamic polarization curves,electrochemical impedance spectroscopy(EIS),hydrogen evolution and MTS colorimetric assay with L929 cells.All three coatings improve the corrosion behavior and cytotoxicity of the alloy.Particularly,HfO_(2)coatings were characterized by the highest corrosion resistance and cell viability,slightly higher than those of ZrO_(2)coatings.TiO_(2)was characterized by the lowest corrosion improvements and,though generally considered a biocompatible coating,was found to not meet the demands for cellular applications(it was characterized by grade 3 cytotoxicity after 5 days of culture).These results reveal a strong link between biocompatibility and corrosion resistance and entail the need of taking the latter into consideration in the choice of a biocompatible coating to protect degradable Mg-based alloys.展开更多
Sharp interfaces in optoelectronic devices are key for proper band alignment. Despite its benefits as buffer layer, ZnS deposited via atomic layer deposition(ALD) renders intermixed interfaces to its substrate, which ...Sharp interfaces in optoelectronic devices are key for proper band alignment. Despite its benefits as buffer layer, ZnS deposited via atomic layer deposition(ALD) renders intermixed interfaces to its substrate, which can be detrimental for device performance. Here, we are attempting to elucidate the chemical species deriving from this metal-oxide to metal-sulfide transition studying ultrathin film ZnS on SiO_2 using high resolution X-ray photoluminescence spectroscopy(XPS).Regarding the S 2p spectra after a deposition of only three cycles of ZnS, we discover the many different chemical species in which S is present. These include intermediate oxides such as SO_4^(2-).These species become more obvious as we tilt the sample in the XPS chamber to shallower angles.Comparing the Si 2p and S 2p high resolution peaks in the depth profile, one can clearly uncover the confinement of SO_4^(2-) to the interface of the underlying substrate. This may indicate that SiO_2/ZnS interfaces contain interfacial sulphates that likely alter the electronic configuration of this interface.展开更多
Electrical contact materials are generally Ag-or Cu-based composites and play a critical role in ensuring the reliability and efficiency of electrical equipments and electronic instruments.The MAX(M is an early transi...Electrical contact materials are generally Ag-or Cu-based composites and play a critical role in ensuring the reliability and efficiency of electrical equipments and electronic instruments.The MAX(M is an early transition metal,A is an element from III or IV main groups,and X is carbon or/and nitrogen)phase ceramics display a unique combination of properties and may serve as an ideal reinforcement phase for electrical contact materials.The biological materials evolved in nature generally exhibit three-dimensional(3D)interpenetrating-phase architectures,which may offer useful inspiration for the architectural design of electrical contact materials.Here,a series of bi-continuous Ag-Ti_(3)SiC_(2) MAX phase composites with high ceramic contents exceeding 50 vol.%and having micron-and ultrafine-scaled 3D interpenetrating-phase architectures,wherein both constituents were continuous and mutually interspersed,were exploited by pressureless infiltration of Ag melt into partially sintered Ti_(3)SiC_(2) scaffolds.The mechanical and electrical properties as well as the friction and wear performance of the composites were investigated and revealed to be closely dependent on the ceramic contents and characteristic structural dimensions.The composites exhibited a good combination of properties with high hardness over 2.3 GPa,high flexural strength exceeding 530 MPa,decent fracture toughness over 10 MPa·m^(1/2),and good wear resistance with low wear rate at an order of 10^(-5)mm^(3)/(N·m),which were much superior compared to the counterparts made by powder metallurgy methods.In particular,the hardness,electrical conductivity,strength,and fracture toughness of the composites demonstrated a simultaneous improvement as the structure was refined from micron-to ultrafine-scales at equivalent ceramic contents.The good combination of properties along with the facile processing route makes the Ag-Ti_(3)SiC_(2)3D interpenetrating-phase composites appealing for electrical contact applications.展开更多
Manipulating the architecture of materials to achieve optimal combinations of properties(inverse design)has always been the dream of materials scientists and engineers.Lattices represent an efficient way to obtain lig...Manipulating the architecture of materials to achieve optimal combinations of properties(inverse design)has always been the dream of materials scientists and engineers.Lattices represent an efficient way to obtain lightweight yet strong materials,providing a high degree of tailorability.Despite massive research has been done on lattice architectures,the inverse design problem of complex phenomena(such as structural instability)has remained elusive.Via deep neural network and genetic algorithm,we provide a machine-learning-based approach to inverse-design non-uniformly assembled lattices.Combining basic building blocks,our approach allows us to independently control the geometry and topology of periodic and aperiodic structures.As an example,we inverse-design lattice architectures with superior buckling performance,outperforming traditional reinforced grid-like and bio-inspired lattices by~30–90%and 10–30%,respectively.Our results provide insights into the buckling behavior of beam-based lattices,opening an avenue for possible applications in modern structures and infrastructures.展开更多
文摘Potential engineering applications of magnesium(Mg)and Mg-based alloys,as the lightest structural metal,have made them a popular subject of study.However,the inferior corrosion and wear characteristics significantly limit their application range.It is widely recognized that surface treatment is the most commonly utilized technique for remarkably improving a substrate’s surface characteristics.Numerous methods have been introduced for the surface treatment of Mg and Mg-based alloys to improve their corrosion behavior and tribological performance.Among these,thermal spray(TS)technology provides several methods for deposition of various functional metallic,ceramic,cermet,or other coatings tailored to particular conditions.Recent researches have shown the tremendous potential for thermal spray coated Mg alloys for biomedical and industrial applications.In this context,the cold spray(CS)method,as a comparatively new TS coating technique,can generate the coating layer using kinetic energy rather than combined thermal and kinetic energies,like the high-velocity oxy-fuel(HVOF)spray method.Moreover,the CS process,as a revolutionary method,is able to repair and refurbish with a faster turnaround time;it also provides solutions that do not require dealing with the thermal stresses that are part of the other repair processes,such as welding or other TS processes using a high-temperature flame.In this review paper,the recently designed coatings that are specifically applied to Mg alloys(primarily for industrial applications)employing various coating processes are reviewed.Because of the increased utilization of CS technology for both 3D printed(additively manufactured)coatings and repair of structurally critical components,the most recent CS methods for the surface treatment,repair,and refurbishment of Mg alloys as well as their benefits and restrictions are then discussed and reviewed in detail.Lastly,the prospects of this field of study are briefly discussed,along with a summary of the presented work.
文摘This study investigates the effect of graphene oxide(GO)on the mechanical and corrosion behavior,antibacterial performance,and cell response of Mg–Zn–Mn(MZM)nanocomposite.MZM/GO nanocomposites with different amounts of GO(i.e.,0.5 wt%,1.0 wt%,and1.5 wt%)were fabricated by the semi-powder metallurgy method.The influence of GO on the MZM nanocomposite was analyzed through the hardness,compressive,corrosion,antibacterial,and cytotoxicity tests.The experimental results showed that,with the increase in the amount of GO(0.5 wt%and 1.5 wt%),the hardness value,compressive strength,and antibacterial performance of the MZM nanocomposite increased,whereas the cell viability and osteogenesis level decreased after the addition of 1.5 wt%GO.Moreover,the electrochemical examination results showed that the corrosion behavior of the MZM alloy was significantly enhanced after encapsulation in 0.5 wt%GO.In summary,MZM nanocomposites reinforced with GO can be used for implant applications because of their antibacterial performance and mechanical property.
文摘The increasing demand for energy absorbent structures,paired with the need for more efficient use of materials in a wide range of engineering fields,has led to an extensive range of designs in the porous forms of sandwiches,honeycomb,and foams.To achieve an even better performance,an ingenious solution is to learn how biological structures adjust their configurations to absorb energy without catastrophic failure.In this study,we have attempted to blend the shape freedom,offered by additive manufacturing techniques,with the biomimetic approach,to propose new lattice structures for energy absorbent applications.To this aim we have combined multiple bio-inspirational sources for the design of optimized configurations under compressive loads.Periodic lattice structures are fabricated based on the designed unit cell geometries and studied using experimental and computational strategies.The individual effect of each bio-inspired feature has been evaluated on the energy absorbance performance of the designed structure.Based on the design parameters of the lattices,a tuning between the strength and energy absorption could be obtained,paving the way for transition within a wide range of real-life applicative scenarios.
文摘Magnesium alloys have been widely studied as materials for temporary implants,but their use has been limited by their corrosion rate.Recently,coatings have been proven to provide an effective barrier.Though only little explored in the field,Atomic Layer Deposition(ALD)stands out as a coating technology due to the outstanding film conformality and density achievable.Here,we provide first insights into the corrosion behavior and the induced biological response of 100 nm thick ALD TiO_(2),HfO_(2)and ZrO_(2)coatings on AZ31 alloy by means of potentiodynamic polarization curves,electrochemical impedance spectroscopy(EIS),hydrogen evolution and MTS colorimetric assay with L929 cells.All three coatings improve the corrosion behavior and cytotoxicity of the alloy.Particularly,HfO_(2)coatings were characterized by the highest corrosion resistance and cell viability,slightly higher than those of ZrO_(2)coatings.TiO_(2)was characterized by the lowest corrosion improvements and,though generally considered a biocompatible coating,was found to not meet the demands for cellular applications(it was characterized by grade 3 cytotoxicity after 5 days of culture).These results reveal a strong link between biocompatibility and corrosion resistance and entail the need of taking the latter into consideration in the choice of a biocompatible coating to protect degradable Mg-based alloys.
基金support from Center on Nanostructuring for Efficient Energy Conversion(CNEEC)at Stanford University,an Energy Frontier Research Center funded by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences under Award Number DESC0001060 the Austrian Research Fund(FWF)under the contract J3505-N20
文摘Sharp interfaces in optoelectronic devices are key for proper band alignment. Despite its benefits as buffer layer, ZnS deposited via atomic layer deposition(ALD) renders intermixed interfaces to its substrate, which can be detrimental for device performance. Here, we are attempting to elucidate the chemical species deriving from this metal-oxide to metal-sulfide transition studying ultrathin film ZnS on SiO_2 using high resolution X-ray photoluminescence spectroscopy(XPS).Regarding the S 2p spectra after a deposition of only three cycles of ZnS, we discover the many different chemical species in which S is present. These include intermediate oxides such as SO_4^(2-).These species become more obvious as we tilt the sample in the XPS chamber to shallower angles.Comparing the Si 2p and S 2p high resolution peaks in the depth profile, one can clearly uncover the confinement of SO_4^(2-) to the interface of the underlying substrate. This may indicate that SiO_2/ZnS interfaces contain interfacial sulphates that likely alter the electronic configuration of this interface.
基金supports from the National Key R&D Program of China(No.2020YFA0710404)the National Natural Science Foundation of China(No.52173269),the KC Wong Education Foundation(No.GJTD-2020-09)the Liaoning Revitalization Talents Program,and the Youth Innovation Promotion Association CAS(No.2019191).
文摘Electrical contact materials are generally Ag-or Cu-based composites and play a critical role in ensuring the reliability and efficiency of electrical equipments and electronic instruments.The MAX(M is an early transition metal,A is an element from III or IV main groups,and X is carbon or/and nitrogen)phase ceramics display a unique combination of properties and may serve as an ideal reinforcement phase for electrical contact materials.The biological materials evolved in nature generally exhibit three-dimensional(3D)interpenetrating-phase architectures,which may offer useful inspiration for the architectural design of electrical contact materials.Here,a series of bi-continuous Ag-Ti_(3)SiC_(2) MAX phase composites with high ceramic contents exceeding 50 vol.%and having micron-and ultrafine-scaled 3D interpenetrating-phase architectures,wherein both constituents were continuous and mutually interspersed,were exploited by pressureless infiltration of Ag melt into partially sintered Ti_(3)SiC_(2) scaffolds.The mechanical and electrical properties as well as the friction and wear performance of the composites were investigated and revealed to be closely dependent on the ceramic contents and characteristic structural dimensions.The composites exhibited a good combination of properties with high hardness over 2.3 GPa,high flexural strength exceeding 530 MPa,decent fracture toughness over 10 MPa·m^(1/2),and good wear resistance with low wear rate at an order of 10^(-5)mm^(3)/(N·m),which were much superior compared to the counterparts made by powder metallurgy methods.In particular,the hardness,electrical conductivity,strength,and fracture toughness of the composites demonstrated a simultaneous improvement as the structure was refined from micron-to ultrafine-scales at equivalent ceramic contents.The good combination of properties along with the facile processing route makes the Ag-Ti_(3)SiC_(2)3D interpenetrating-phase composites appealing for electrical contact applications.
基金Open access funding provided by Norwegian University of Science and Technology.
文摘Manipulating the architecture of materials to achieve optimal combinations of properties(inverse design)has always been the dream of materials scientists and engineers.Lattices represent an efficient way to obtain lightweight yet strong materials,providing a high degree of tailorability.Despite massive research has been done on lattice architectures,the inverse design problem of complex phenomena(such as structural instability)has remained elusive.Via deep neural network and genetic algorithm,we provide a machine-learning-based approach to inverse-design non-uniformly assembled lattices.Combining basic building blocks,our approach allows us to independently control the geometry and topology of periodic and aperiodic structures.As an example,we inverse-design lattice architectures with superior buckling performance,outperforming traditional reinforced grid-like and bio-inspired lattices by~30–90%and 10–30%,respectively.Our results provide insights into the buckling behavior of beam-based lattices,opening an avenue for possible applications in modern structures and infrastructures.
