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
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
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
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
Numerical simulation and experiments were introduced to develop AA4045/AA3003 cladding billets with different clad-ratios. The temperature fields, microstructures and mechanical properties near interface were investig...Numerical simulation and experiments were introduced to develop AA4045/AA3003 cladding billets with different clad-ratios. The temperature fields, microstructures and mechanical properties near interface were investigated in detail. The results show that cladding billets with different clad-ratios were fabricated successfully. Si and Mn elements diffused across the bonding interface and formed diffusion layer. With the increase of clad-layer thickness, the interfacial region transforms from semisolid-solid state to liquid-solid state and the diffusion layer increased from 10 to 25 μm. The hardness at interface is higher than that of AA3003 side but lower than that of the other side. The bonding strength increased with the clad-layer thickness, attributing to solution strengthening due to elements diffusion. The cladding billets were extruded into clad pipe by indirect extrusion process after homogenization. The clad pipe remained the interfacial characteristics of as-cast cladding billet and the heredity of clad-ratio during deformation was testified.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
Tungsten inert gas（TIG） welding was applied to creating a composite layer on the surface of cast aluminum alloy A380. Different mixtures of Al, Si and SiC powders mixed with sodium silicate solution were pasted on s...Tungsten inert gas（TIG） welding was applied to creating a composite layer on the surface of cast aluminum alloy A380. Different mixtures of Al, Si and SiC powders mixed with sodium silicate solution were pasted on substrates. Surface melting was conducted by TIG welding to produce Al-SiC layer on the surface. Microstructural evolution was investigated by X-ray diffractometry（XRD）, optical and scanning electron microscopy（SEM） and elemental microanalysis（EDS）. Properties of clad layers were studied by microhardness and sliding wear testing. The results showed a uniform distribution of SiC particles in dendritic aluminum matrix. Addition of excess silicon caused the formation of eutectic crystals and coarse silicon particles in the clad layer which resulted in higher hardness and wear resistance of clad layers.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
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.
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.
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Project(2015B090926013)supported by the Science and Technology Program of Guangdong Province,ChinaProject(20170540307)supported by the Natural Science Foundation of Liaoning Province,China
文摘Numerical simulation and experiments were introduced to develop AA4045/AA3003 cladding billets with different clad-ratios. The temperature fields, microstructures and mechanical properties near interface were investigated in detail. The results show that cladding billets with different clad-ratios were fabricated successfully. Si and Mn elements diffused across the bonding interface and formed diffusion layer. With the increase of clad-layer thickness, the interfacial region transforms from semisolid-solid state to liquid-solid state and the diffusion layer increased from 10 to 25 μm. The hardness at interface is higher than that of AA3003 side but lower than that of the other side. The bonding strength increased with the clad-layer thickness, attributing to solution strengthening due to elements diffusion. The cladding billets were extruded into clad pipe by indirect extrusion process after homogenization. The clad pipe remained the interfacial characteristics of as-cast cladding billet and the heredity of clad-ratio during deformation was testified.
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Tungsten inert gas（TIG） welding was applied to creating a composite layer on the surface of cast aluminum alloy A380. Different mixtures of Al, Si and SiC powders mixed with sodium silicate solution were pasted on substrates. Surface melting was conducted by TIG welding to produce Al-SiC layer on the surface. Microstructural evolution was investigated by X-ray diffractometry（XRD）, optical and scanning electron microscopy（SEM） and elemental microanalysis（EDS）. Properties of clad layers were studied by microhardness and sliding wear testing. The results showed a uniform distribution of SiC particles in dendritic aluminum matrix. Addition of excess silicon caused the formation of eutectic crystals and coarse silicon particles in the clad layer which resulted in higher hardness and wear resistance of clad layers.
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.
