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
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
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
Laser multi\|layer cladding experiments were performed on the substrate of DD3 single crystal with FGH95 powder as cladding material. The solidification microstructure in the sample was investigated. It was found th...Laser multi\|layer cladding experiments were performed on the substrate of DD3 single crystal with FGH95 powder as cladding material. The solidification microstructure in the sample was investigated. It was found that the solidification microstructure was greatly influenced by the crystallography orientation of the substrate and the local solidification conditions. When the angle between the preferred orientation of the single crystal and the direction of heat flow in the cladding layer is less than 30°, single crystal cladding layers were acquired. Otherwise the crystallography orientation of the cladding layer will deviate from the orientation of the substrate and the microstructure with polycrystalline appears. Meanwhile, even when the experiments were performed on the same preferred crystal surface, the solidification microstructures will be different distinctly resulting from the variation of the local solidification conditions. The secondary arms were degenerated and the primary arm spacing was about 10\|20 μm. Further investigation shows that the phases of the cladding layer are mainly made up of γ,γ′ , the flower\|like γ/γ′ eutectic and carbide. The morphology of γ′ was cubical and the size is less than 0.1μm. {展开更多
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
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
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
Cermet/iron alloy cladding layers were coated on the surface of Al-Mg-Si alloy (A6061) plates by resistance seam welding method with tungsten carbide (WC) and high-carbon iron alloy (SHA) powders. The cladding l...Cermet/iron alloy cladding layers were coated on the surface of Al-Mg-Si alloy (A6061) plates by resistance seam welding method with tungsten carbide (WC) and high-carbon iron alloy (SHA) powders. The cladding layer consisted of WC reinforcement, SHA binder, A6061 and FeAl3. The effect of WC ratio (30 wt%, 50 wt% and 70 wt%) on the microstructure and wear behavior of the cladding layers was investigated in detail. Abrasive wear test was performed under two kinds of load condition by using a rubber wheel apparatus to evaluate wear resistance. The results showed that the wear resistance of the cladding layer was improved by 3.5-5 times than that of the substrate. At lower load, the wear resistances of the samples 30% and 70% WC were nearly the same, which suggested that FeAl3 played an important role in improvement of the wear resistance instead of WC. While at higher load, the amount of WC determined the wear resistance of the cladding layer. Furthermore, wear behavior of these cladding layers was explained with reference to the observed microstructure of the worn surface.展开更多
The variation law of cladding thickness as well as the structures and properties of H90-steel clad strip produced by inversion solidification was studied. The interface bonding mechanisms were approached. It is found ...The variation law of cladding thickness as well as the structures and properties of H90-steel clad strip produced by inversion solidification was studied. The interface bonding mechanisms were approached. It is found that the thickness of H90 cladding goes sequentially through the solidification growth stage, holding stage, and remelting stage, with an increase in immersion time. The higher the preheating temperature of the steel coil, the thicker is the maximum cladding thickness. Observation by using optical microscopy (OM) and the electron probe microanalyzer (EPMA) shows that the microstructure of H90 cladding is composed of equiaxed grains, and that interdiffusion between Cu and Fe at interface occurs but obvious diffusion of Zn and the intermetallic layer are not observed. The diffusion layer is thin and about 4 μm. Multipass small reduction cold rolling and repeated bending tests show that the interface is firmly bonded. Tensile test shows that the mechanical properties of the as-clad strips can meet the requirements of GB5213-2001 for the F-grade deep-drawing steel plate though there is a slight difference in the mechanical properties among the clad strips with different cladding thickness.展开更多
c-plane GaN-based blue laser diodes(LDs) were fabricated with Al-free cladding layers(CLs) and deepened etching depth of mesa structure, so the aspect ratio of the far-field pattern(FFP) of the laser beam can be...c-plane GaN-based blue laser diodes(LDs) were fabricated with Al-free cladding layers(CLs) and deepened etching depth of mesa structure, so the aspect ratio of the far-field pattern(FFP) of the laser beam can be reduced to as low as 1.7, which is nearly the same as conventional AlGa In P-based red LDs. By using GaN CLs,the radiation angle of the laser beam θ⊥ is only 10.1° in the direction perpendicular to the junction plane. After forming a deeply etched mesa, the beam divergence angle parallel to the junction plane of FFP, θ;, increases from4.9° to 5.8°. After using the modified structure, the operation voltage of LD is effectively reduced by 2 V at an injection current of 50 mA, but the threshold current value increases. The etching damage may be one of the main reasons responsible for the increase of the threshold current.展开更多
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.
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.
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National Key Basic Research Development Program me of china(No.G2 0 0 0 0 672 0 5 -3 )
文摘Laser multi\|layer cladding experiments were performed on the substrate of DD3 single crystal with FGH95 powder as cladding material. The solidification microstructure in the sample was investigated. It was found that the solidification microstructure was greatly influenced by the crystallography orientation of the substrate and the local solidification conditions. When the angle between the preferred orientation of the single crystal and the direction of heat flow in the cladding layer is less than 30°, single crystal cladding layers were acquired. Otherwise the crystallography orientation of the cladding layer will deviate from the orientation of the substrate and the microstructure with polycrystalline appears. Meanwhile, even when the experiments were performed on the same preferred crystal surface, the solidification microstructures will be different distinctly resulting from the variation of the local solidification conditions. The secondary arms were degenerated and the primary arm spacing was about 10\|20 μm. Further investigation shows that the phases of the cladding layer are mainly made up of γ,γ′ , the flower\|like γ/γ′ eutectic and carbide. The morphology of γ′ was cubical and the size is less than 0.1μm. {
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Cermet/iron alloy cladding layers were coated on the surface of Al-Mg-Si alloy (A6061) plates by resistance seam welding method with tungsten carbide (WC) and high-carbon iron alloy (SHA) powders. The cladding layer consisted of WC reinforcement, SHA binder, A6061 and FeAl3. The effect of WC ratio (30 wt%, 50 wt% and 70 wt%) on the microstructure and wear behavior of the cladding layers was investigated in detail. Abrasive wear test was performed under two kinds of load condition by using a rubber wheel apparatus to evaluate wear resistance. The results showed that the wear resistance of the cladding layer was improved by 3.5-5 times than that of the substrate. At lower load, the wear resistances of the samples 30% and 70% WC were nearly the same, which suggested that FeAl3 played an important role in improvement of the wear resistance instead of WC. While at higher load, the amount of WC determined the wear resistance of the cladding layer. Furthermore, wear behavior of these cladding layers was explained with reference to the observed microstructure of the worn surface.
基金Item Sponsored by Hi-Tech Research and Development Program of China (863-715-009-006)
文摘The variation law of cladding thickness as well as the structures and properties of H90-steel clad strip produced by inversion solidification was studied. The interface bonding mechanisms were approached. It is found that the thickness of H90 cladding goes sequentially through the solidification growth stage, holding stage, and remelting stage, with an increase in immersion time. The higher the preheating temperature of the steel coil, the thicker is the maximum cladding thickness. Observation by using optical microscopy (OM) and the electron probe microanalyzer (EPMA) shows that the microstructure of H90 cladding is composed of equiaxed grains, and that interdiffusion between Cu and Fe at interface occurs but obvious diffusion of Zn and the intermetallic layer are not observed. The diffusion layer is thin and about 4 μm. Multipass small reduction cold rolling and repeated bending tests show that the interface is firmly bonded. Tensile test shows that the mechanical properties of the as-clad strips can meet the requirements of GB5213-2001 for the F-grade deep-drawing steel plate though there is a slight difference in the mechanical properties among the clad strips with different cladding thickness.
基金supported by the National Key R&D Program(Nos.2017YFB0403100,2017YFB0403101)the National Natural Science Foundation of China(Nos.61534007,61404156,61522407,61604168,61775230)+7 种基金the Key Frontier Scientific Research Program of the Chinese Academy of Sciences(No.QYZDB-SSW-JSC014)the Science and Technology Service Network Initiative of the Chinese Academy of Sciences,the Key R&D Program of Jiangsu Province(No.BE2017079)the Natural Science Foundation of Jiangsu Province(No.BK20160401)the China Postdoctoral Science Foundation(No.2016M591944)supported by the Open Fund of the State Key Laboratory of Luminescence and Applications(No.SKLA-2016-01)the Open Fund of the State Key Laboratory on Integrated Optoelectronics(Nos.IOSKL2016KF04,IOSKL2016KF07)the Seed Fund from SINANO,CAS(No.Y5AAQ51001)supported technically by Nano Fabrication Facility,Platform for Characterization&Test,Nano-X of SINANO,CAS
文摘c-plane GaN-based blue laser diodes(LDs) were fabricated with Al-free cladding layers(CLs) and deepened etching depth of mesa structure, so the aspect ratio of the far-field pattern(FFP) of the laser beam can be reduced to as low as 1.7, which is nearly the same as conventional AlGa In P-based red LDs. By using GaN CLs,the radiation angle of the laser beam θ⊥ is only 10.1° in the direction perpendicular to the junction plane. After forming a deeply etched mesa, the beam divergence angle parallel to the junction plane of FFP, θ;, increases from4.9° to 5.8°. After using the modified structure, the operation voltage of LD is effectively reduced by 2 V at an injection current of 50 mA, but the threshold current value increases. The etching damage may be one of the main reasons responsible for the increase of the threshold current.