A mathematical model for describing the melting process in the medium-frequency induction furnace was developed.Finite difference method was applied to deal with coupling electromagnetic field and temperature field in...A mathematical model for describing the melting process in the medium-frequency induction furnace was developed.Finite difference method was applied to deal with coupling electromagnetic field and temperature field in the melting process.The magnetic induction,temperature distribution and the phase interface moving characteristic during melting of the furnace burden were calculated.The effects of the direct current and inductive heating frequency on the process were analyzed.The simulation results show that:In the direction of burden radius,magnetic induction decreases from the outside of the burden to the center.Solid/liquid interface moves gradually from the outside of the burden to the center.The movement speed increases when the burden begins to melt.In the direction of the burden height,the distribution of eddy current in the surface is accord with the edge effect of the coil.Solid/liquid interface moves gradually from the center to the two sides.The direct current has a greater effect on the electromagnetic field and temperature field than frequency.展开更多
The induction brazing of brass to steel using Ag-Cu-Zn-Sn filler metal was investigated in this study. The influence of A8 content on the microstructure and properties were analyzed by means of optical microscopy, sca...The induction brazing of brass to steel using Ag-Cu-Zn-Sn filler metal was investigated in this study. The influence of A8 content on the microstructure and properties were analyzed by means of optical microscopy, scanning electron microscopy and electron probe microanalysis. Defect free joint was achieved using Ag- Cu-Zn-Sn filler metal. The microstructure of the joint was mainly composed of Ag-based solid solution and Cu-based solid solution. The increase of A8 content and the cooling rate both led to the increase of the needle like eutectic structure. The tensile strength decreased with the increase of Ag content. The tensile strength at room temperature using Ag25CuZnSn filler metal reached 445 MPa. All fractures using Ag-Cu-Zn-Sn filler metal presented ductile characteristic.展开更多
The vacuum induction brazing of SiC particulate reinforced LY12 alloy matrix composite using Al-28Cu-5Si-2Mg filler metal has been carried out. The micrograph of the joint interface was observed by scanning electron m...The vacuum induction brazing of SiC particulate reinforced LY12 alloy matrix composite using Al-28Cu-5Si-2Mg filler metal has been carried out. The micrograph of the joint interface was observed by scanning electron microscopy. The joint strength was determined by shear tests. The results show that brazing temperature, holding time, SiC particle volume percentage and post heat treatment influence joint strength. SiC particles happen in the brazing seam and the distribution of SiC particles in the joint is not uniform. Particle-poor zones in the joint exist near the base metal, and particle concentrate zones exist in the center of the brazing seam. In addition, the failure of the composite is predominantly initiated by the rooting of SiC particle in the brazing seam and the micro-crack expanded along the brazing seam with low energy.展开更多
BNi-2/WC composite wear-resisting coating was prepared on carbon steel by the method of induction brazing.The microstructure and phase composition of the composite coating were analyzed,and the bonding strength and we...BNi-2/WC composite wear-resisting coating was prepared on carbon steel by the method of induction brazing.The microstructure and phase composition of the composite coating were analyzed,and the bonding strength and wear-resisting performance of the coating were tested.During the process of induction brazing,the tungsten carbide partially dissolves and reacts with the filler metal alloy to form NiW compound phase,which realizes the metallurgical combination of tungsten carbide and filler metal alloy.The matrix of the filler metal alloy consists of Ni solid solution and Ni_(3)B/Ni_(3)Si eutectic phase,and the metallurgical diffusion reaction occurs between the filler metal alloy and the steel matrix.The mechanical analysis results show that the self-strength of the composite coating reaches 140 MPa and the bonding strength of the filler metal alloy to the steel matrix reaches 360 MPa.The dry sand rubber wheel wear testing machine showed that the coating weight loss was only 0.2824 g,which was only 1/5 of the weight loss of 65 Mn matrix under the same conditions.展开更多
The nickel-based coating with different TiC addition was fabricated onto 45 steel substrate by using induction brazed technology in air.The effect of TiC addition on the microstructure and wear resistance of induction...The nickel-based coating with different TiC addition was fabricated onto 45 steel substrate by using induction brazed technology in air.The effect of TiC addition on the microstructure and wear resistance of induction brazing coating was studied.The results show that the microstructure of brazing coating is strengthened and refined by adding TiC.With the increase of the amount of TiC added,the amount of TiC in the Ni-based matrix is increased,and the matrix structure is obviously refined.This is because the high melting point TiC particles can be used as heterogeneous nucleation cores,thus refining the Ni based matrix structure.Moreover,the wear resistance of brazing coating is improved due to the addition of TiC.展开更多
Profiled monolayer cBN wheel was induction brazed for grinding of titanium dovetail slot in this study.Aimed at acquiring a uniform temperature distribution along the profiled surface and reducing the thermal deformat...Profiled monolayer cBN wheel was induction brazed for grinding of titanium dovetail slot in this study.Aimed at acquiring a uniform temperature distribution along the profiled surface and reducing the thermal deformation of the brazed wheel,a finite element model was established to investigate the temperature uniformity during induction brazing.A suitable induction coil and the related working parameters were designed and chosen based on the simulation results.Ag-Cu-Ti alloy and cBN grains were applied in the induction brazing experiment.The results showed geometric deformation of the brazed wheel was no more than 0.01 mm and chemical reaction layer were found on the brazed joint interface.Further validation tests were carried out by grinding of Ti-6 Al-4 V alloy.Compared to the electroplated wheel,the brazed wheel showed better performance such as low specific grinding energy and good ground quality in grinding of Ti-6 Al-4 V alloy.Abrasion wear was found to be the main failure mode for the induction brazed wheel,while adhesion and grains pull-out were the main failure mode for the electroplated wheel.展开更多
Nickel-coated 45 steel studs and 6061 aluminum alloy with 4047 A1 alloy foil as filler metal were joined by using high frequency induction brazing. The microstrueture of Fe/A1 brazed joint was studied by means of opti...Nickel-coated 45 steel studs and 6061 aluminum alloy with 4047 A1 alloy foil as filler metal were joined by using high frequency induction brazing. The microstrueture of Fe/A1 brazed joint was studied by means of optical microscopy （OM）, scanning electron microscope （SEM）, energy dispersive X-ray （EDX）, and X-ray diffraction （XRD）. Results showed that 45 steel stud and 6061 aluminum alloy could be successfully joined by high frequency induction brazing with proper processing parameters. The bonding strength of the joint was of the order of 88 MPa. Ni coating on steel stud successfully avoided the generation of Fe-AI intermetallic compound which is brittle by blocking the contact between A1 and Fe. Intermetallic compounds, i e, AI3Ni2, AlmNi0.9 and A10.3Fe3Si0.7 presented in AI side, FeNi and Fe-A1-Ni ternary eutectic structure were formed in Fe side. The micro-hardness in intermetallic compound layer was 313 HV. The joint was brittle fractured in the intermetallic compounds layer of A1 side, where plenty of A13Ni2 intermetallie compounds were distributed continuously.展开更多
Residual stresses produced in polycrystalline CBN abrasive grits during a high-frequency induction brazing process are calculated by using ?nite element analysis, with a consideration of the nonuniform temperature dis...Residual stresses produced in polycrystalline CBN abrasive grits during a high-frequency induction brazing process are calculated by using ?nite element analysis, with a consideration of the nonuniform temperature distribution in the induction brazing model. The in?uences of induction brazing parameters on the residual stresses of polycrystalline CBN abrasive grits have been analyzed, including the embedding depth, grit side length, etc. Results obtained show that the tensile stress with a 40% embedding depth is 292 MPa, which is the minimum on the bonding interface compared with other embedding depths. Meanwhile, the maximum tensile stress is 575 MPa, with an increase of 59% compared with that of a grit side length of 50 mm. Finally, the simulation results of the brazing residual stress of polycrystalline CBN abrasive grits have been con?rmed valid based on the residual stress measurement of the brazed monocrystalline CBN grit.展开更多
Oxygen-free copper and pre-metalized graphite were brazed using CuNiSnP braze alloy by high frequency induction heating method. Interracial microstructures and reaction phases were analyzed by scanning electron micros...Oxygen-free copper and pre-metalized graphite were brazed using CuNiSnP braze alloy by high frequency induction heating method. Interracial microstructures and reaction phases were analyzed by scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDS）. The strength and resistance of the joints were tested. It is found that when the brazing parameters are optimized, the structures of the joints are graphite/（Cu,Ni）/Ni（s.s）＋NixPy/Cu3P＋Cu（s.s） （including Sn）＋eutectic structures （Cu3P＋Ni3P＋Cu（s.s）/Cu （s.s）/Cu）. When the temperature increases to 750℃ or the holding time prolongs to 300 s, the eutectie structures disappear and the amount of Cu3P increases. The maximum shear strength of the joints is 5.2 MPa, which fracture at the interface of graphite and metallization. The resistance of the joints is no more than 5 mΩ.展开更多
Induction brazecoating technology is an important means to improve the surface properties of materials.In this paper,copper plate and corundum are selected as substrates for induction brazecoating respectively.The tem...Induction brazecoating technology is an important means to improve the surface properties of materials.In this paper,copper plate and corundum are selected as substrates for induction brazecoating respectively.The temperature variation of powder and paste coating is systematically studied,and the heat conduction mode and path in the brazecoating process are analyzed.The results show that rise of the coating temperature mainly depends on the heat absorption from the substrate.The liquid-solid interface conducts heat violently and advances step by step,which promotes the melting spread of metal filler metal.The powdery brazecoating material is in a free state,and there is a gas insulation film between the powder particles and the diamond,making it difficult for substrate to conduct heat to the coating.The binder not only assists forming,shell making and oxygen isolation,but also plays an important role during melting.展开更多
In order to prepare monolayer brazed superabrasive wheels, the polycrystalline cubic boron nitride（PCBN）grains were brazed to AISI 1045 steel matrix with Ag–Cu–Ti filler alloy using the high-frequency induction he...In order to prepare monolayer brazed superabrasive wheels, the polycrystalline cubic boron nitride（PCBN）grains were brazed to AISI 1045 steel matrix with Ag–Cu–Ti filler alloy using the high-frequency induction heating technique. The compressive strengths of brazed grains were measured. Morphology, chemical composition and phase component of the brazing resultant around PCBN grain were also characterized. The results show that the maximum compressive strength of brazed grains is obtained in the case of brazing temperature of 965 °C, which does not decrease the original grain strength. Strong joining between Ag–Cu–Ti alloy and PCBN grains is dependent on the brazing resultants,such as TiB_2, TiN and AlTi_3, the formation mechanism of which is also discussed. Under the given experimental conditions, the optimum heating parameters were determined to be current magnitude of 24 A and scanning speed of0.5 mm/s. Finally, the brazing-induced residual tensile stress, which has a great influence on the grain fracture behavior in grinding, was determined through finite element analysis.展开更多
Brazing hard alloy to high strength steel, incomplete atomic diffusion and excessive brittle reaction product precipitation at the faying interface are usually suffered because of incomplete understanding the process ...Brazing hard alloy to high strength steel, incomplete atomic diffusion and excessive brittle reaction product precipitation at the faying interface are usually suffered because of incomplete understanding the process of the initial interface disappearing and diffusion layer forming and evolving. In this paper , hard alloy YG11C （ WC-11wt. %Co） and high strength steel 42CrMo were picked up as base metals and BCu64MnNi as filler metal to clarify the interfacial microstrncture evolution. The process parameters of dwell time were set as 30 s, 60 s, 120 s, and 300 s and braze temperature were set as 950 ℃, 970 ℃, 990 ℃, 1 010 ℃, the effect of which on the evolution of interfacial microstructure, tensile strength, integrated with fracture morphology analysis, were conducted. The results showed that increasing brazing temperature from 950 ℃ to 970 ℃, no signifwant difference existed in the joint interface, whereas brazed at 990 ℃, the binder phase erosion occurred, i. e. the liquid filler metal etched into Co binder phase of WC-Co base metal, which caused WC particles debonding from the base metal surface and formed an micro-anisotropic zone.. Increase temperature to 1 010 ℃, severe binder erosion happened so as to micropores appear. Through the parameters optimization, the tensile strength can reach to the maximum 589 MPa at temperature of 970 ℃. The dwell time showed similar effect on tensile strength because longer dwell time also caused erosion and porosity owing to long-time diffusion and reaction.展开更多
基金Item Sponsored by Program for New Century Excellent Talents in University(NCET-09-0396)State Major Science and Technology Special Project Foundation for High-End Numerical Machine and Basic Manufacturing Equipment(2011ZX04014-052,2012ZX04012-011)
文摘A mathematical model for describing the melting process in the medium-frequency induction furnace was developed.Finite difference method was applied to deal with coupling electromagnetic field and temperature field in the melting process.The magnetic induction,temperature distribution and the phase interface moving characteristic during melting of the furnace burden were calculated.The effects of the direct current and inductive heating frequency on the process were analyzed.The simulation results show that:In the direction of burden radius,magnetic induction decreases from the outside of the burden to the center.Solid/liquid interface moves gradually from the outside of the burden to the center.The movement speed increases when the burden begins to melt.In the direction of the burden height,the distribution of eddy current in the surface is accord with the edge effect of the coil.Solid/liquid interface moves gradually from the center to the two sides.The direct current has a greater effect on the electromagnetic field and temperature field than frequency.
基金supported by the National Natural Science Foundation of China (No. 50805038)Program for New Century Excellent Talents in University
文摘The induction brazing of brass to steel using Ag-Cu-Zn-Sn filler metal was investigated in this study. The influence of A8 content on the microstructure and properties were analyzed by means of optical microscopy, scanning electron microscopy and electron probe microanalysis. Defect free joint was achieved using Ag- Cu-Zn-Sn filler metal. The microstructure of the joint was mainly composed of Ag-based solid solution and Cu-based solid solution. The increase of A8 content and the cooling rate both led to the increase of the needle like eutectic structure. The tensile strength decreased with the increase of Ag content. The tensile strength at room temperature using Ag25CuZnSn filler metal reached 445 MPa. All fractures using Ag-Cu-Zn-Sn filler metal presented ductile characteristic.
文摘The vacuum induction brazing of SiC particulate reinforced LY12 alloy matrix composite using Al-28Cu-5Si-2Mg filler metal has been carried out. The micrograph of the joint interface was observed by scanning electron microscopy. The joint strength was determined by shear tests. The results show that brazing temperature, holding time, SiC particle volume percentage and post heat treatment influence joint strength. SiC particles happen in the brazing seam and the distribution of SiC particles in the joint is not uniform. Particle-poor zones in the joint exist near the base metal, and particle concentrate zones exist in the center of the brazing seam. In addition, the failure of the composite is predominantly initiated by the rooting of SiC particle in the brazing seam and the micro-crack expanded along the brazing seam with low energy.
基金supported by the National Natural Science Foundation of China(Grant No.U2004186).
文摘BNi-2/WC composite wear-resisting coating was prepared on carbon steel by the method of induction brazing.The microstructure and phase composition of the composite coating were analyzed,and the bonding strength and wear-resisting performance of the coating were tested.During the process of induction brazing,the tungsten carbide partially dissolves and reacts with the filler metal alloy to form NiW compound phase,which realizes the metallurgical combination of tungsten carbide and filler metal alloy.The matrix of the filler metal alloy consists of Ni solid solution and Ni_(3)B/Ni_(3)Si eutectic phase,and the metallurgical diffusion reaction occurs between the filler metal alloy and the steel matrix.The mechanical analysis results show that the self-strength of the composite coating reaches 140 MPa and the bonding strength of the filler metal alloy to the steel matrix reaches 360 MPa.The dry sand rubber wheel wear testing machine showed that the coating weight loss was only 0.2824 g,which was only 1/5 of the weight loss of 65 Mn matrix under the same conditions.
基金supported by the 2020 Ningbo“3315 Talent Introduction Plan”Innovative Team(C-Class)the major project of Ningbo“Scientific and Technological Innovation 2025”(Grant No.2020Z111)Science and Technology Major Project of Zhejiang Province(No.203ZP20220161)。
文摘The nickel-based coating with different TiC addition was fabricated onto 45 steel substrate by using induction brazed technology in air.The effect of TiC addition on the microstructure and wear resistance of induction brazing coating was studied.The results show that the microstructure of brazing coating is strengthened and refined by adding TiC.With the increase of the amount of TiC added,the amount of TiC in the Ni-based matrix is increased,and the matrix structure is obviously refined.This is because the high melting point TiC particles can be used as heterogeneous nucleation cores,thus refining the Ni based matrix structure.Moreover,the wear resistance of brazing coating is improved due to the addition of TiC.
基金the National Natural Science Foundation of China(Nos.51905234,51805231,51975264,51905275,51705463)。
文摘Profiled monolayer cBN wheel was induction brazed for grinding of titanium dovetail slot in this study.Aimed at acquiring a uniform temperature distribution along the profiled surface and reducing the thermal deformation of the brazed wheel,a finite element model was established to investigate the temperature uniformity during induction brazing.A suitable induction coil and the related working parameters were designed and chosen based on the simulation results.Ag-Cu-Ti alloy and cBN grains were applied in the induction brazing experiment.The results showed geometric deformation of the brazed wheel was no more than 0.01 mm and chemical reaction layer were found on the brazed joint interface.Further validation tests were carried out by grinding of Ti-6 Al-4 V alloy.Compared to the electroplated wheel,the brazed wheel showed better performance such as low specific grinding energy and good ground quality in grinding of Ti-6 Al-4 V alloy.Abrasion wear was found to be the main failure mode for the induction brazed wheel,while adhesion and grains pull-out were the main failure mode for the electroplated wheel.
基金Funded by the National Defense Basic Research Program(No.A2620110005)the Equipment Pre Research Project of Eleventh Five-Year Plan of China(No.40401050301)the Natural Science Foundation of Jiangsu Province(No.BK20131261)
文摘Nickel-coated 45 steel studs and 6061 aluminum alloy with 4047 A1 alloy foil as filler metal were joined by using high frequency induction brazing. The microstrueture of Fe/A1 brazed joint was studied by means of optical microscopy （OM）, scanning electron microscope （SEM）, energy dispersive X-ray （EDX）, and X-ray diffraction （XRD）. Results showed that 45 steel stud and 6061 aluminum alloy could be successfully joined by high frequency induction brazing with proper processing parameters. The bonding strength of the joint was of the order of 88 MPa. Ni coating on steel stud successfully avoided the generation of Fe-AI intermetallic compound which is brittle by blocking the contact between A1 and Fe. Intermetallic compounds, i e, AI3Ni2, AlmNi0.9 and A10.3Fe3Si0.7 presented in AI side, FeNi and Fe-A1-Ni ternary eutectic structure were formed in Fe side. The micro-hardness in intermetallic compound layer was 313 HV. The joint was brittle fractured in the intermetallic compounds layer of A1 side, where plenty of A13Ni2 intermetallie compounds were distributed continuously.
基金supported by the National Natural Science Foundation of China(No.51775275)the Fundamental Research Funds for the Central Universities(No.NE2014103 and No.NZ2016107)
文摘Residual stresses produced in polycrystalline CBN abrasive grits during a high-frequency induction brazing process are calculated by using ?nite element analysis, with a consideration of the nonuniform temperature distribution in the induction brazing model. The in?uences of induction brazing parameters on the residual stresses of polycrystalline CBN abrasive grits have been analyzed, including the embedding depth, grit side length, etc. Results obtained show that the tensile stress with a 40% embedding depth is 292 MPa, which is the minimum on the bonding interface compared with other embedding depths. Meanwhile, the maximum tensile stress is 575 MPa, with an increase of 59% compared with that of a grit side length of 50 mm. Finally, the simulation results of the brazing residual stress of polycrystalline CBN abrasive grits have been con?rmed valid based on the residual stress measurement of the brazed monocrystalline CBN grit.
基金Project(50705022) supported by the National Natural Science Foundation of ChinaProject supported by the Program for New Century Excellent Talents in University
文摘Oxygen-free copper and pre-metalized graphite were brazed using CuNiSnP braze alloy by high frequency induction heating method. Interracial microstructures and reaction phases were analyzed by scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDS）. The strength and resistance of the joints were tested. It is found that when the brazing parameters are optimized, the structures of the joints are graphite/（Cu,Ni）/Ni（s.s）＋NixPy/Cu3P＋Cu（s.s） （including Sn）＋eutectic structures （Cu3P＋Ni3P＋Cu（s.s）/Cu （s.s）/Cu）. When the temperature increases to 750℃ or the holding time prolongs to 300 s, the eutectie structures disappear and the amount of Cu3P increases. The maximum shear strength of the joints is 5.2 MPa, which fracture at the interface of graphite and metallization. The resistance of the joints is no more than 5 mΩ.
基金supported by the 2020 Ningbo “3315 Talent Introduction Plan” Innovative Team (C-Class)the major project of Ningbo “Scientific and Technological Innovation 2025”(Grant No.2020Z111)Science and Technology Major Project of Zhejiang Province (No.203ZP20220161)
文摘Induction brazecoating technology is an important means to improve the surface properties of materials.In this paper,copper plate and corundum are selected as substrates for induction brazecoating respectively.The temperature variation of powder and paste coating is systematically studied,and the heat conduction mode and path in the brazecoating process are analyzed.The results show that rise of the coating temperature mainly depends on the heat absorption from the substrate.The liquid-solid interface conducts heat violently and advances step by step,which promotes the melting spread of metal filler metal.The powdery brazecoating material is in a free state,and there is a gas insulation film between the powder particles and the diamond,making it difficult for substrate to conduct heat to the coating.The binder not only assists forming,shell making and oxygen isolation,but also plays an important role during melting.
基金financially supported by the National Natural Science Foundation of China(Nos.51235004 and51375235)the Fundamental Research Funds for the Central Universities(No.NE2014103)the Funding for Outstanding Doctoral Dissertation in NUAA(No.BCXJ16-06)
文摘In order to prepare monolayer brazed superabrasive wheels, the polycrystalline cubic boron nitride（PCBN）grains were brazed to AISI 1045 steel matrix with Ag–Cu–Ti filler alloy using the high-frequency induction heating technique. The compressive strengths of brazed grains were measured. Morphology, chemical composition and phase component of the brazing resultant around PCBN grain were also characterized. The results show that the maximum compressive strength of brazed grains is obtained in the case of brazing temperature of 965 °C, which does not decrease the original grain strength. Strong joining between Ag–Cu–Ti alloy and PCBN grains is dependent on the brazing resultants,such as TiB_2, TiN and AlTi_3, the formation mechanism of which is also discussed. Under the given experimental conditions, the optimum heating parameters were determined to be current magnitude of 24 A and scanning speed of0.5 mm/s. Finally, the brazing-induced residual tensile stress, which has a great influence on the grain fracture behavior in grinding, was determined through finite element analysis.
基金This work was supported by the National Natural Science Foundation of China （ Grant No. 51475376 and No. 51575451 ） and the Research Fund of the State Key Laboratory of Solidification Processing （NWPU）, China （Grant No. 109-QP-2014）.
文摘Brazing hard alloy to high strength steel, incomplete atomic diffusion and excessive brittle reaction product precipitation at the faying interface are usually suffered because of incomplete understanding the process of the initial interface disappearing and diffusion layer forming and evolving. In this paper , hard alloy YG11C （ WC-11wt. %Co） and high strength steel 42CrMo were picked up as base metals and BCu64MnNi as filler metal to clarify the interfacial microstrncture evolution. The process parameters of dwell time were set as 30 s, 60 s, 120 s, and 300 s and braze temperature were set as 950 ℃, 970 ℃, 990 ℃, 1 010 ℃, the effect of which on the evolution of interfacial microstructure, tensile strength, integrated with fracture morphology analysis, were conducted. The results showed that increasing brazing temperature from 950 ℃ to 970 ℃, no signifwant difference existed in the joint interface, whereas brazed at 990 ℃, the binder phase erosion occurred, i. e. the liquid filler metal etched into Co binder phase of WC-Co base metal, which caused WC particles debonding from the base metal surface and formed an micro-anisotropic zone.. Increase temperature to 1 010 ℃, severe binder erosion happened so as to micropores appear. Through the parameters optimization, the tensile strength can reach to the maximum 589 MPa at temperature of 970 ℃. The dwell time showed similar effect on tensile strength because longer dwell time also caused erosion and porosity owing to long-time diffusion and reaction.
