The Multi layer coating of Ni60 alloy was got by multi layer laser cladding. The height of the coating was about 12mm and the wall of the coating was perpendicular to the base. The microstructure of the coating was ...The Multi layer coating of Ni60 alloy was got by multi layer laser cladding. The height of the coating was about 12mm and the wall of the coating was perpendicular to the base. The microstructure of the coating was made up of fine dendrite. The conjunction between layers was good.展开更多
TIG welding was used to deposit Co-8.8 Al-9.8 W-0.2 B superalloy on 304 austenite stainless steel. The form factor of weld, dilution ratio, microhardness, microstructure and distribution of alloying elements were inve...TIG welding was used to deposit Co-8.8 Al-9.8 W-0.2 B superalloy on 304 austenite stainless steel. The form factor of weld, dilution ratio, microhardness, microstructure and distribution of alloying elements were investigated. The microstructure of cladding layer was mainly hypoeutectic. The primary phases were cobalt-rich solid solution. The eutectic phase was composed of cobalt-rich solid solution,Co6W6C and Co Cx. When the boron content increased from 0.2% to 0.5%,the dilution ratio decreased,the primary phase became coarse and the microhardness decreased. When the boron content was from 0.5% to 2%,the dilution ratio and microhardness increased obviously,but the primary phase was refined.The hard phase of Co-8.8 Al-9.8 W became refined and the amount was raised,and the performance of cladding layer was improved with appropriate boron increase.展开更多
Ni-based alloy coating on 21-4-N heat-resistant steel was prepared using CO2 laser, and the high-temperature abrasion wear was tested. The microstructure of this cladding layer and its abrasion wear behavior at high t...Ni-based alloy coating on 21-4-N heat-resistant steel was prepared using CO2 laser, and the high-temperature abrasion wear was tested. The microstructure of this cladding layer and its abrasion wear behavior at high temperature by changing compositions and temperatures were investigated by means of optical microscope and scanning electron microscope. Among the three compositions of cladding layer, i.e. Ni21+20%WC+0.5%CeO2, Ni25+20%WC+0.5%CeO2 and Ni60+20%WC+0.5%CeO2, the experimental results show that Ni21+20%WC+ 0.5%CeO2 cladding layer is made up of finer grains, and presents the best abrasion wear behavior at high temperature. The wear pattern of laser cladding layer is mainly grain abrasion at lower temperature, and it would be changed to adhesive abrasion and oxide abrasion at higher temperature.展开更多
By laser multi-layer cladding using a pulsed Nd-YAG irradiation the thickness of the cladding zone Mg-based alloys(ZM2 and ZM5) can reach about 1.0 mm.The microstructure of the substrate and the cladding zone was stud...By laser multi-layer cladding using a pulsed Nd-YAG irradiation the thickness of the cladding zone Mg-based alloys(ZM2 and ZM5) can reach about 1.0 mm.The microstructure of the substrate and the cladding zone was studied using optical microscope, scanning electron microscopy(SEM), X-ray diffractometry(XRD) and micro hardness analysis. It is observed that constituent of ZM5 alloy is δ+Mg 17Al 12, that of ZM2 alloy is α+MgZn+Mg 9Ce. That of cladding layer ZM2 alloy(L-ZM2) is Mg+Mg 2Zn 11+MgCe; while that of the cladding layer ZM5 alloy(L-ZM5) is Mg+Mg 32(Al, Zn) 49. The hardness of the cladding area can be increased to values above HV127. Very fine uniform microstructure and the produced new phases of nanometer/sub-micrometer order were obtained. Now, many repaired Mg-based alloy components have been passed by flying test in outside field.展开更多
In this paper, the influence of preheating on the layer microstructure and properties is analyzed in the layer metal microstructure. The influence of preheating temperature on the shape and amount of primary carbides ...In this paper, the influence of preheating on the layer microstructure and properties is analyzed in the layer metal microstructure. The influence of preheating temperature on the shape and amount of primary carbides and borides little, but on initial γ-dendrites is large. With the increasing of preheating temperature, little by little the γ-dendrites , which grown from parent material to layer, are flourishing to disappearing, and the microhardness at the center of the layer is increasing.展开更多
Laser cladding,together with laser nitriding was used to synthesize a titanium nickel intermetallic compound layer on the nickel substrate and a TiN coating on the cladding layer. During the laser cladding, Ti and Ni ...Laser cladding,together with laser nitriding was used to synthesize a titanium nickel intermetallic compound layer on the nickel substrate and a TiN coating on the cladding layer. During the laser cladding, Ti and Ni powders were blown into the melting pool by a six-hole coaxial nozzle powder injection system. Exothermic reactions between Ti and Ni took place in the melting pool, and a cladding layer of titanium nickel intermetallic compounds was produced. Laser nitriding in a nitrogen-rich atmosphere followed the production of the cladding layer, and formed a golden yellow TiN layer over it. An optical and a scanning electron microscope were used to investigate the microstructures and measure the thicknesses of the cladding layer and the TiN layer. Phase identification was carried out by XRD. For the nitriding sample, the microhardness profile of the clad layer was tested. The optimal process parameters of the in situ synthesis of titanium nickel intermetallic compounds were obtained.展开更多
A novel model was presented to predict the evolutionary development of cladding layer, and a method based on Lambert-Beer theorem and Mie's theory was adopted to treat the interaction between powder stream and las...A novel model was presented to predict the evolutionary development of cladding layer, and a method based on Lambert-Beer theorem and Mie's theory was adopted to treat the interaction between powder stream and laser beam. By using the continuum model and enthalpy-porosity method, the fluid flow and heat transfer in solid-liquid phase change system were simulated. The commercial software PHOENICS, to which several modules were appended, was used to accomplish the simulation. Numerical computation was performed for Stellite 6 cladding on steel, the obtained results are coincident with those measured in experiment basically.展开更多
The laser cladding of Ni1015 alloy on Cu substrate was prepared by a high power continuous wave CO2 laser. Its microstructure was analyzed by optical microscope （OM）, scanning electron microscope （SEM）, and X-Ray ...The laser cladding of Ni1015 alloy on Cu substrate was prepared by a high power continuous wave CO2 laser. Its microstructure was analyzed by optical microscope （OM）, scanning electron microscope （SEM）, and X-Ray diffraction （XRD）. The average microhardness of the cladding coating was Hv 280, which was almost three times of that of the Cu substrate （Hv 85）. OM and SEM observations showed that the obtained coating had a smooth and uniform surface, as well as a metallurgical combination with the Cu substrate without cracks and pores at the interface. With the addition of copper into the nickel-based alloy, the differences of thermal expansion coefficient and melting point between the interlayer and cladding were reduced, which resulted in low stresses during rapid cooling. Moreover, large amount of （Cu, Ni） solid solution formed a metallurgical bonding between the cladding coating and the substrate, which also relaxed the stresses, leading to the reduction of interfacial cracks and pores after laser cladding.展开更多
The 3d transition-metal nickel(Ni)-based cathodes have long been widely used in rechargeable batteries for over 100 years,from Ni-based alkaline rechargeable batteries,such as nickel-cadmium(Ni-Cd)and nickel-metal hyd...The 3d transition-metal nickel(Ni)-based cathodes have long been widely used in rechargeable batteries for over 100 years,from Ni-based alkaline rechargeable batteries,such as nickel-cadmium(Ni-Cd)and nickel-metal hydride(Ni-MH)batteries,to the Ni-rich cathode featured in lithium-ion batteries(LIBs).Ni-based alkaline batteries were first invented in the 1900s,and the well-developed Ni-MH batteries were used on a large scale in Toyota Prius vehicles in the mid-1990s.Around the same time,however,Sony Corporation commercialized the first LIBs in camcorders.After temporally fading as LiCoO_(2) dominated the cathode in LIBs,nickel oxide-based cathodes eventually found their way back to the mainstreaming battery industry.The uniqueness of Ni in batteries is that it helps to deliver high energy density and great storage capacity at a low cost.This review mainly provides a comprehensive overview of the key role of Ni-based cathodes in rechargeable batteries.After presenting the physical and chemical properties of the 3d transition-metal Ni,which make it an optimal cationic redox center in the cathode of batteries,we introduce the structure,reaction mechanism,and modification of nickel hydroxide electrode in Ni-Cd and Ni-MH rechargeable batteries.We then move on to the Ni-based layered oxide cathode in LIBs,with a focus on the structure,issues,and challenges of layered oxides,LiNiO_(2),and LiNi_(1−x−y)Co_(x)Mn_(y)O_(2).The role of Ni in the electrochemical performance and thermal stability of the Ni-rich cathode is highlighted.By bridging the“old”Ni-based batteries and the“modern”Ni-rich cathode in the LIBs,this review is committed to providing insights into the Ni-based electrochemistry and material design,which have been under research and development for over 100 years.This overview would shed new light on the development of advanced Ni-containing batteries with high energy density and long cycle life.展开更多
Using self-made impact fatigue test instruments and related analytic devices,the mechanical components with laser cladding layer have been attempted. It is found that, onrepeated impact force, several failure modes of...Using self-made impact fatigue test instruments and related analytic devices,the mechanical components with laser cladding layer have been attempted. It is found that, onrepeated impact force, several failure modes of the components include the surface cracks, surfaceplastic deformation, corrosive pitting and coat collapse, etc. The paper reported the test methodand initial analysis conclusions about the unique failure characteristics of the mechanicalcomponents on repeated impact load.展开更多
TiC/Ti composite layers were produced by laser melting the preplaced mixture of Ti and TiC powders. The results show that the microstructure, microhardness and wear resistance of the clad layer are all evaluated. The ...TiC/Ti composite layers were produced by laser melting the preplaced mixture of Ti and TiC powders. The results show that the microstructure, microhardness and wear resistance of the clad layer are all evaluated. The composite layer consists of TiC and α-Ti phases. TiC in the clad zone exists in the form of fine dendrites and Ti fills among TiC dendrites, which has a typical structure of TiC/Ti composite. The microhardness of the composite coating is significantly enhanced as high as HV_ 0.2940 as compared to HV_ 0.2345 of the substrate region. The composite layer has excellent wear resistance compared to titanium alloy.展开更多
The effects of heat treatment on tnicrostructure and hardness of laser surface-clad Ni2 !+20%WC+0.5%CeO2 on the heat-resistant cast iron were investigated by means of X-ray diffraction(XRD), transmission electron micr...The effects of heat treatment on tnicrostructure and hardness of laser surface-clad Ni2 !+20%WC+0.5%CeO2 on the heat-resistant cast iron were investigated by means of X-ray diffraction(XRD), transmission electron microscope(TEM) and microhardness test. The experimental results showed that heat-treating at 500’C has no effect on microstructure and hardness of the layers. Although the phase composition of the layers heat-treated at 700°C and 800°C remain unchanged, more Ni3B and N14B3 phases are precipitated on the matrix of the cladding layer, the metastable phase—M7C3 is transformed into steady phase—M23C6, and the precipitated phases coarsened.展开更多
文摘The Multi layer coating of Ni60 alloy was got by multi layer laser cladding. The height of the coating was about 12mm and the wall of the coating was perpendicular to the base. The microstructure of the coating was made up of fine dendrite. The conjunction between layers was good.
基金supported by the National Natural Science Foundation of China(Grant No.51561019)
文摘TIG welding was used to deposit Co-8.8 Al-9.8 W-0.2 B superalloy on 304 austenite stainless steel. The form factor of weld, dilution ratio, microhardness, microstructure and distribution of alloying elements were investigated. The microstructure of cladding layer was mainly hypoeutectic. The primary phases were cobalt-rich solid solution. The eutectic phase was composed of cobalt-rich solid solution,Co6W6C and Co Cx. When the boron content increased from 0.2% to 0.5%,the dilution ratio decreased,the primary phase became coarse and the microhardness decreased. When the boron content was from 0.5% to 2%,the dilution ratio and microhardness increased obviously,but the primary phase was refined.The hard phase of Co-8.8 Al-9.8 W became refined and the amount was raised,and the performance of cladding layer was improved with appropriate boron increase.
文摘Ni-based alloy coating on 21-4-N heat-resistant steel was prepared using CO2 laser, and the high-temperature abrasion wear was tested. The microstructure of this cladding layer and its abrasion wear behavior at high temperature by changing compositions and temperatures were investigated by means of optical microscope and scanning electron microscope. Among the three compositions of cladding layer, i.e. Ni21+20%WC+0.5%CeO2, Ni25+20%WC+0.5%CeO2 and Ni60+20%WC+0.5%CeO2, the experimental results show that Ni21+20%WC+ 0.5%CeO2 cladding layer is made up of finer grains, and presents the best abrasion wear behavior at high temperature. The wear pattern of laser cladding layer is mainly grain abrasion at lower temperature, and it would be changed to adhesive abrasion and oxide abrasion at higher temperature.
文摘By laser multi-layer cladding using a pulsed Nd-YAG irradiation the thickness of the cladding zone Mg-based alloys(ZM2 and ZM5) can reach about 1.0 mm.The microstructure of the substrate and the cladding zone was studied using optical microscope, scanning electron microscopy(SEM), X-ray diffractometry(XRD) and micro hardness analysis. It is observed that constituent of ZM5 alloy is δ+Mg 17Al 12, that of ZM2 alloy is α+MgZn+Mg 9Ce. That of cladding layer ZM2 alloy(L-ZM2) is Mg+Mg 2Zn 11+MgCe; while that of the cladding layer ZM5 alloy(L-ZM5) is Mg+Mg 32(Al, Zn) 49. The hardness of the cladding area can be increased to values above HV127. Very fine uniform microstructure and the produced new phases of nanometer/sub-micrometer order were obtained. Now, many repaired Mg-based alloy components have been passed by flying test in outside field.
文摘In this paper, the influence of preheating on the layer microstructure and properties is analyzed in the layer metal microstructure. The influence of preheating temperature on the shape and amount of primary carbides and borides little, but on initial γ-dendrites is large. With the increasing of preheating temperature, little by little the γ-dendrites , which grown from parent material to layer, are flourishing to disappearing, and the microhardness at the center of the layer is increasing.
文摘Laser cladding,together with laser nitriding was used to synthesize a titanium nickel intermetallic compound layer on the nickel substrate and a TiN coating on the cladding layer. During the laser cladding, Ti and Ni powders were blown into the melting pool by a six-hole coaxial nozzle powder injection system. Exothermic reactions between Ti and Ni took place in the melting pool, and a cladding layer of titanium nickel intermetallic compounds was produced. Laser nitriding in a nitrogen-rich atmosphere followed the production of the cladding layer, and formed a golden yellow TiN layer over it. An optical and a scanning electron microscope were used to investigate the microstructures and measure the thicknesses of the cladding layer and the TiN layer. Phase identification was carried out by XRD. For the nitriding sample, the microhardness profile of the clad layer was tested. The optimal process parameters of the in situ synthesis of titanium nickel intermetallic compounds were obtained.
基金supported by the National Natural Science Foundation of China(No.59871038)the Foundation of State Key Laboratory of Laser Technology,Huazhong University of Science and Technology
文摘A novel model was presented to predict the evolutionary development of cladding layer, and a method based on Lambert-Beer theorem and Mie's theory was adopted to treat the interaction between powder stream and laser beam. By using the continuum model and enthalpy-porosity method, the fluid flow and heat transfer in solid-liquid phase change system were simulated. The commercial software PHOENICS, to which several modules were appended, was used to accomplish the simulation. Numerical computation was performed for Stellite 6 cladding on steel, the obtained results are coincident with those measured in experiment basically.
基金This research was financially supported by the National Natural Science Foundation of China (No.50574020) and Shanghai BaoSteel Group Co.
文摘The laser cladding of Ni1015 alloy on Cu substrate was prepared by a high power continuous wave CO2 laser. Its microstructure was analyzed by optical microscope （OM）, scanning electron microscope （SEM）, and X-Ray diffraction （XRD）. The average microhardness of the cladding coating was Hv 280, which was almost three times of that of the Cu substrate （Hv 85）. OM and SEM observations showed that the obtained coating had a smooth and uniform surface, as well as a metallurgical combination with the Cu substrate without cracks and pores at the interface. With the addition of copper into the nickel-based alloy, the differences of thermal expansion coefficient and melting point between the interlayer and cladding were reduced, which resulted in low stresses during rapid cooling. Moreover, large amount of （Cu, Ni） solid solution formed a metallurgical bonding between the cladding coating and the substrate, which also relaxed the stresses, leading to the reduction of interfacial cracks and pores after laser cladding.
基金financially supported by the China Postdoctoral Science Foundation(No.2021M700396)the National Natural Science Foundation of China(No.52102206)。
文摘The 3d transition-metal nickel(Ni)-based cathodes have long been widely used in rechargeable batteries for over 100 years,from Ni-based alkaline rechargeable batteries,such as nickel-cadmium(Ni-Cd)and nickel-metal hydride(Ni-MH)batteries,to the Ni-rich cathode featured in lithium-ion batteries(LIBs).Ni-based alkaline batteries were first invented in the 1900s,and the well-developed Ni-MH batteries were used on a large scale in Toyota Prius vehicles in the mid-1990s.Around the same time,however,Sony Corporation commercialized the first LIBs in camcorders.After temporally fading as LiCoO_(2) dominated the cathode in LIBs,nickel oxide-based cathodes eventually found their way back to the mainstreaming battery industry.The uniqueness of Ni in batteries is that it helps to deliver high energy density and great storage capacity at a low cost.This review mainly provides a comprehensive overview of the key role of Ni-based cathodes in rechargeable batteries.After presenting the physical and chemical properties of the 3d transition-metal Ni,which make it an optimal cationic redox center in the cathode of batteries,we introduce the structure,reaction mechanism,and modification of nickel hydroxide electrode in Ni-Cd and Ni-MH rechargeable batteries.We then move on to the Ni-based layered oxide cathode in LIBs,with a focus on the structure,issues,and challenges of layered oxides,LiNiO_(2),and LiNi_(1−x−y)Co_(x)Mn_(y)O_(2).The role of Ni in the electrochemical performance and thermal stability of the Ni-rich cathode is highlighted.By bridging the“old”Ni-based batteries and the“modern”Ni-rich cathode in the LIBs,this review is committed to providing insights into the Ni-based electrochemistry and material design,which have been under research and development for over 100 years.This overview would shed new light on the development of advanced Ni-containing batteries with high energy density and long cycle life.
文摘Using self-made impact fatigue test instruments and related analytic devices,the mechanical components with laser cladding layer have been attempted. It is found that, onrepeated impact force, several failure modes of the components include the surface cracks, surfaceplastic deformation, corrosive pitting and coat collapse, etc. The paper reported the test methodand initial analysis conclusions about the unique failure characteristics of the mechanicalcomponents on repeated impact load.
文摘TiC/Ti composite layers were produced by laser melting the preplaced mixture of Ti and TiC powders. The results show that the microstructure, microhardness and wear resistance of the clad layer are all evaluated. The composite layer consists of TiC and α-Ti phases. TiC in the clad zone exists in the form of fine dendrites and Ti fills among TiC dendrites, which has a typical structure of TiC/Ti composite. The microhardness of the composite coating is significantly enhanced as high as HV_ 0.2940 as compared to HV_ 0.2345 of the substrate region. The composite layer has excellent wear resistance compared to titanium alloy.
文摘The effects of heat treatment on tnicrostructure and hardness of laser surface-clad Ni2 !+20%WC+0.5%CeO2 on the heat-resistant cast iron were investigated by means of X-ray diffraction(XRD), transmission electron microscope(TEM) and microhardness test. The experimental results showed that heat-treating at 500’C has no effect on microstructure and hardness of the layers. Although the phase composition of the layers heat-treated at 700°C and 800°C remain unchanged, more Ni3B and N14B3 phases are precipitated on the matrix of the cladding layer, the metastable phase—M7C3 is transformed into steady phase—M23C6, and the precipitated phases coarsened.
