The reliability of the coated industry components demands ideal fatigue properties of the coating,and it is mainly determined by the performance of the interfaces.In this study,pulsed magnetic treatment(PMT)was applie...The reliability of the coated industry components demands ideal fatigue properties of the coating,and it is mainly determined by the performance of the interfaces.In this study,pulsed magnetic treatment(PMT)was applied to the thermal sprayed WC-10Co4Cr coating,and the fatigue lifetime of the coated bolt increased by 219.82%under an imitation of the operating mode condition.Scratch tests further proved that both the adhesion and cohesion strength were improved after PMT,and they benefit from the interface strengthening effects.The formation of coherent WC/Co interfaces was characterized by in-situ transmission electron microscopy(TEM),and the molecular dynamic simulations indicate that the work of separation of these interfaces is much higher than the original disordered ones.Residual stress was relaxed and distributed more homogeneously after PMT,and it mainly contributes to the coating/substrate strengthening.This work provides a new post-treatment method focusing on the interfaces in the WC-based coating and gives insight into its mechanism so that it is hopeful to be applied to other kinds of coatings.展开更多
Dissimilar welding of AZ31/ZK60 magnesium alloys with a thickness of 2 mm was successfully carried out by the double-sided friction stir spot welding with adjustable probes.A dissimilar joint bearing flat surfaces on ...Dissimilar welding of AZ31/ZK60 magnesium alloys with a thickness of 2 mm was successfully carried out by the double-sided friction stir spot welding with adjustable probes.A dissimilar joint bearing flat surfaces on both sides without a keyhole was obtained and the shear failure load of 8.7±0.5 kN was reached.The role of the adjustable probes has been revealed in detail.In the center of the stir zone,the welding interface structure was heterogeneous around which some distinct oxides still remained,leading to a weak interface strength.On the contrary,the welding interface structure around the shoulder/probe interface was homogeneous with no oxides giving rise to a strong interface strength,which is attributed to the severe material flow introduced by the adjustable probes.In addition,the vicinity outside the shoulder/probe interface,where the fracture occurred during the shear tensile tests,was also strengthened owing to the shearing and torsion by the adju stable probes.Therefore,a stable plug failure can be obtained and the joint properties can be improved.展开更多
Mg/Al bimetal combines the advantages of both aluminum and magnesium and has broad application prospects in automotive, aerospace,weapons, digital products and so on. The compound casting has the characteristics of lo...Mg/Al bimetal combines the advantages of both aluminum and magnesium and has broad application prospects in automotive, aerospace,weapons, digital products and so on. The compound casting has the characteristics of low cost, easy to achieve metallurgical combination and suitable for the preparation of complex bimetallic parts. However, bimetallic joint strength is low due to differences of physical properties between Al and Mg, oxide film on metallic surface and interfacial Al-Mg IMCs, which is closely related to the interfacial microstructure and properties. Therefore, how to control the interface of the bimetal to achieve performance enhancement is the focus and difficulty in this field. At present, there are mainly the following strengthening methods. First, the “zincate galvanizing” and “electrolytic polishing+anodic oxidation” technology were exert on the surface of Al alloy to remove and break the oxide film, which improved the wettability between Al and Mg. Second, the undesirable Al-Mg IMCs were reduce or elimination by adding the interlayers(Zn, Ni and Ni-Cu). Thirdly, the evolution process of interfacial microstructure was changed and fine strengthening phases were formed by adding Si element to Al alloy or rare earth element to Mg alloy. Fourthly, mechanical vibration and ultrasonic vibration were applied in the process of the filling and solidification to refine and homogenize the interfacial structure. Finally, some other methods, including secondary rolling, thermal modification, heat treatment and constructing exterior 3D morphology, also can be used to regulate the interfacial microstructure and compositions. The above strengthening methods can be used alone or in combination to achieve bimetallic strengthening. Finally, the future development direction of the Mg/Al bimetal is prospected, which provides some new ideas for the development and application of the Mg/Al bimetal.展开更多
There is keen interest in using Ti alloys as lightweight structural materials for aerospace and automotive industries.However,a long-standing problem for these materials is their poor oxidation resistance.Herein,we de...There is keen interest in using Ti alloys as lightweight structural materials for aerospace and automotive industries.However,a long-standing problem for these materials is their poor oxidation resistance.Herein,we designed and fabricated a Ti_(5)Si_(3) reinforced Ti-4(wt.%)Mo composite with two-scale network architecture by low energy milling and spark plasma sintering.It displays superior oxidation resistance at 800°C owing to the in-situ formation of a multi-component surface layer.This oxide layer has a dense grain size gradient structure that consists of an outer TiO_(2)layer and an inner SiO_(2)-padding-TiO_(2) layer,which has remarkable oxidation resistance and thermal stability.Furthermore,it was revealed that the hitherto unknown interaction between Ti_(5)Si_(3) reinforcement and nitrogen during oxidation would contribute to the formation of a TiN nano-twin interface layer,which accommodates the thermal mismatch strain between the oxide layer and matrix.This,along with high adhesion,confers excellent thermal cycling life with no cracking or spallation during long-term oxidation.In this regard,the secure operating temperature of this new composite can be increased to 800°C,which provides a design pathway for a new family of Ti matrix composites for high-temperature applications.展开更多
High-performance thick electrodes are regarded as a feasible strategy for enhancing the energy density of lithium-ion batteries.However,fast ion transport and long-life cyclability in thick cathode remain significant ...High-performance thick electrodes are regarded as a feasible strategy for enhancing the energy density of lithium-ion batteries.However,fast ion transport and long-life cyclability in thick cathode remain significant challenges.Here,we developed a multidirectional-ion-transport Ni-rich thick cathode LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811),which exhibits excellent consecutive layer-by-layer contact and fast ion-flow diffusion,achieving high areal capacity and superior rate capability toward 3D-printed batteries.By balancing the viscosity of electrode inks and mechanical strength of thick electrodes,a multilayer NCM811 cathode with strong interfacial bonding,reaching an electrode thickness of 3 mm and ultra-high mass loading of 185 mg cm^(-2),delivers a record areal capacity of 38.4 mAh cm^(-2)up to date.The 3D-printed porous frameworks featuring the multidirectional transport of Li ion and superior affinity of electrolyte,exceptionally boost active material utilization and fast electrochemical kinetics of thick electrodes,resulting in a high specific capacity of 208 mAh g^(-1).Furthermore,the printed electrode has a capacity retention rate of 88%after 150 cycles at 2 C.A full cell assembled with a printed NCM811 cathode and graphite anode shows high energy density of 417 Wh kg^(-1)at electrode level and long-term cyclability.This work provides an effective strategy for fabricating long-lifespan and high-energy-density lithium-ion batteries.展开更多
基金This study was financially supported by National Key R&D Program of China(No.2020YFA0714900)National Natural Science Foundation of China(No.52031003)the Defense Industrial Technology Development Program(No.JCKY2020110B007).
文摘The reliability of the coated industry components demands ideal fatigue properties of the coating,and it is mainly determined by the performance of the interfaces.In this study,pulsed magnetic treatment(PMT)was applied to the thermal sprayed WC-10Co4Cr coating,and the fatigue lifetime of the coated bolt increased by 219.82%under an imitation of the operating mode condition.Scratch tests further proved that both the adhesion and cohesion strength were improved after PMT,and they benefit from the interface strengthening effects.The formation of coherent WC/Co interfaces was characterized by in-situ transmission electron microscopy(TEM),and the molecular dynamic simulations indicate that the work of separation of these interfaces is much higher than the original disordered ones.Residual stress was relaxed and distributed more homogeneously after PMT,and it mainly contributes to the coating/substrate strengthening.This work provides a new post-treatment method focusing on the interfaces in the WC-based coating and gives insight into its mechanism so that it is hopeful to be applied to other kinds of coatings.
基金financially supported by the New Energy and Industrial Technology Development Organization(NEDO)under the“Innovation Structural Materials Project(Future Pioneering Projects)”。
文摘Dissimilar welding of AZ31/ZK60 magnesium alloys with a thickness of 2 mm was successfully carried out by the double-sided friction stir spot welding with adjustable probes.A dissimilar joint bearing flat surfaces on both sides without a keyhole was obtained and the shear failure load of 8.7±0.5 kN was reached.The role of the adjustable probes has been revealed in detail.In the center of the stir zone,the welding interface structure was heterogeneous around which some distinct oxides still remained,leading to a weak interface strength.On the contrary,the welding interface structure around the shoulder/probe interface was homogeneous with no oxides giving rise to a strong interface strength,which is attributed to the severe material flow introduced by the adjustable probes.In addition,the vicinity outside the shoulder/probe interface,where the fracture occurred during the shear tensile tests,was also strengthened owing to the shearing and torsion by the adju stable probes.Therefore,a stable plug failure can be obtained and the joint properties can be improved.
基金the supports provided by the National Natural Science Foundation of China (Grant Nos.52271102,52075198 and 52205359)the China Post-doctoral Science Foundation (Grant No.2021M691112)the Analytical and Testing Center,HUST。
文摘Mg/Al bimetal combines the advantages of both aluminum and magnesium and has broad application prospects in automotive, aerospace,weapons, digital products and so on. The compound casting has the characteristics of low cost, easy to achieve metallurgical combination and suitable for the preparation of complex bimetallic parts. However, bimetallic joint strength is low due to differences of physical properties between Al and Mg, oxide film on metallic surface and interfacial Al-Mg IMCs, which is closely related to the interfacial microstructure and properties. Therefore, how to control the interface of the bimetal to achieve performance enhancement is the focus and difficulty in this field. At present, there are mainly the following strengthening methods. First, the “zincate galvanizing” and “electrolytic polishing+anodic oxidation” technology were exert on the surface of Al alloy to remove and break the oxide film, which improved the wettability between Al and Mg. Second, the undesirable Al-Mg IMCs were reduce or elimination by adding the interlayers(Zn, Ni and Ni-Cu). Thirdly, the evolution process of interfacial microstructure was changed and fine strengthening phases were formed by adding Si element to Al alloy or rare earth element to Mg alloy. Fourthly, mechanical vibration and ultrasonic vibration were applied in the process of the filling and solidification to refine and homogenize the interfacial structure. Finally, some other methods, including secondary rolling, thermal modification, heat treatment and constructing exterior 3D morphology, also can be used to regulate the interfacial microstructure and compositions. The above strengthening methods can be used alone or in combination to achieve bimetallic strengthening. Finally, the future development direction of the Mg/Al bimetal is prospected, which provides some new ideas for the development and application of the Mg/Al bimetal.
基金financially supported by the National Natural Science Foundation of China(NSFC)[Grant No.51534009]National Key R&D Program of China[Grant No.2017YFB0306001]Natural Science Foundation of Hunan Province China(Grant No.2021JJ40750)。
文摘There is keen interest in using Ti alloys as lightweight structural materials for aerospace and automotive industries.However,a long-standing problem for these materials is their poor oxidation resistance.Herein,we designed and fabricated a Ti_(5)Si_(3) reinforced Ti-4(wt.%)Mo composite with two-scale network architecture by low energy milling and spark plasma sintering.It displays superior oxidation resistance at 800°C owing to the in-situ formation of a multi-component surface layer.This oxide layer has a dense grain size gradient structure that consists of an outer TiO_(2)layer and an inner SiO_(2)-padding-TiO_(2) layer,which has remarkable oxidation resistance and thermal stability.Furthermore,it was revealed that the hitherto unknown interaction between Ti_(5)Si_(3) reinforcement and nitrogen during oxidation would contribute to the formation of a TiN nano-twin interface layer,which accommodates the thermal mismatch strain between the oxide layer and matrix.This,along with high adhesion,confers excellent thermal cycling life with no cracking or spallation during long-term oxidation.In this regard,the secure operating temperature of this new composite can be increased to 800°C,which provides a design pathway for a new family of Ti matrix composites for high-temperature applications.
基金supported by the National Natural Science Foundation of China(22125903,22439003,22479128,22209175,22309176,22209173)the National Key R&D Program of China(2022YFA1504100)+6 种基金the Liaoning Revitalization Talents Program-Leading Talents(XLYC2402032)the United Foundation for Dalian Institute of Chemical Physics,Chinese Academy of Sciences and Shenyang Institute of Automation,Chinese Academy of Sciences(DICP&SIA UN202501)the State Key Laboratory of Catalysis(2024SKL-A-001)the Energy Revolution S&T Program of Yulin Innovation Institute of Clean Energy(E412010508)the S&T Program of Energy Shaanxi Laboratory(ESL B202403)the Natural Science Foundation of Liaoning Province(2023BS006)the China National Postdoctoral Program for Innovative Talents(BX20240334)。
文摘High-performance thick electrodes are regarded as a feasible strategy for enhancing the energy density of lithium-ion batteries.However,fast ion transport and long-life cyclability in thick cathode remain significant challenges.Here,we developed a multidirectional-ion-transport Ni-rich thick cathode LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811),which exhibits excellent consecutive layer-by-layer contact and fast ion-flow diffusion,achieving high areal capacity and superior rate capability toward 3D-printed batteries.By balancing the viscosity of electrode inks and mechanical strength of thick electrodes,a multilayer NCM811 cathode with strong interfacial bonding,reaching an electrode thickness of 3 mm and ultra-high mass loading of 185 mg cm^(-2),delivers a record areal capacity of 38.4 mAh cm^(-2)up to date.The 3D-printed porous frameworks featuring the multidirectional transport of Li ion and superior affinity of electrolyte,exceptionally boost active material utilization and fast electrochemical kinetics of thick electrodes,resulting in a high specific capacity of 208 mAh g^(-1).Furthermore,the printed electrode has a capacity retention rate of 88%after 150 cycles at 2 C.A full cell assembled with a printed NCM811 cathode and graphite anode shows high energy density of 417 Wh kg^(-1)at electrode level and long-term cyclability.This work provides an effective strategy for fabricating long-lifespan and high-energy-density lithium-ion batteries.
