Microstructure and properties of induction brazing nickel base/WC composite coating

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.

Research on the heat conduction mechanism of induction brazecoating

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.

Investigations of high-frequency induction hardening process for piston rod of shock absorber

The microhardness of piston rods treated with different induction hardening processes was tested. The experimental results reveal that the depth of the hardened zone is proportional to the ratio of the moving speed of the piston rod to the output power of the induction generator. This result is proved correct through the Finite Element Method (FEM) simulation of the thermal field of induction heating. From tensile and impact tests, an optimized high frequency induction hardening process for piston rods has been obtained, where the output power was 82%×80 kW and the moving speed of workpiece was 5364 mm/min. The piston rods, treated by the optimized high frequency induction hardening process, show the best comprehensive mechanical performance.

Study on vacuum induction brazing of SiC_p/LY12 composite using Al-Cu-Si-Mg filler metal

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.

Nickel-coated Steel Stud to Aluminum Alloy Joints Made by High Frequency Induction Brazing

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.

Effect of TiC addition on the microstructure and wear resistance of induction brazed nickel-based coating in air

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.

Interfacial characteristics of high frequency induction brazed Cu and pre-metalized graphite joints

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.

Local High-Frequency Heating in Electronics Technology

Modeling and investigation of HF electromagnetic heating in induction devices with unclosed magnetic circuit has allowed to optimize heating speed in local zones of formation of soldering connections and to improve their quality due to joint action of superficial effects and electromagnetic forces.For all magnetic materials is nonlinear decrease in heating power depending on frequency of HF.Installed the optimal parameters of HF heating for soldering electronics modules by inductor with open-ended magnetic conductor.

Compressive Strength and Interface Microstructure of PCBN Grains Brazed with High-Frequency Induction Heating Method

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.

Residual stresses of polycrystalline CBN abrasive grits brazed with a high-frequency induction heating technique

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.

高强Cu/Al接头用的Zn基钎料及Cu表面镀层研究

铜铝接头被广泛应用于电力电子等行业。在长期运行过程中,铜铝接头易出现脆性断裂问题,严重影响其安全服役。进行了锌基钎料的成分设计,分析了钎料的各项性能,得到优化的钎料成分。对铜板表面进行化学镀镍磷层改性,采用感应钎焊和优化的钎料进行了铜铝搭接钎焊试验。结果表明:在锌基钎料中提高Al含量,添加一定量Cu、Ag、稀土元素,可以提升钎料的润湿性能、强度和耐腐蚀性能。镍磷镀层显著提升了锌基钎料在铜板的润湿性能,改变了铜铝接头的界面反应,显著细化了焊缝晶粒。采用优化的锌基钎料和化学镀镍磷层工艺得到的铜铝接头的力学性能得到显著提升,剪切强度达37 MPa,疲劳寿命达85000次。

基于有限元分析的感应钎焊蜂窝板工艺研究

为设计合理的感应线圈结构,并探究不同输入电流、加热时间对焊缝温度最大值的影响,选取适合的工艺参数,从而实现蜂窝板感应钎焊的高效率制备。本文建立了感应钎焊蜂窝板的有限元模型,设计了3种形状的线圈:螺旋形线圈、双回形线圈、M形线圈,并计算得到3种线圈感应钎焊蜂窝板的温度场分布,同时探究了不同工艺参数对温度最大值的影响规律。在模拟的基础上,对Ti_(2)AlNb合金和高温合金组成的蜂窝夹层结构进行钎焊试验,验证了感应钎焊Ti_(2)AlNb/GH4099蜂窝夹层结构具有良好的可行性。结果表明,螺旋形线圈在焊缝处的磁场更加集中,产生的电磁热更多,钎焊效率更高。螺旋形线圈更利于感应钎涂过程中产生大量电磁热,并且当电流为1000 A,加热时间为15 s时钎焊效率最高,且实验得到的Ti_(2)AlNb/GH4099蜂窝夹层结构力学性能优异。

焊接参数对YG16硬质合金/35CrMo钢异质金属焊接接头组织与性能的影响

采用BAg50CuZnCd银基钎料作为填充金属,对YG16硬质合金与35CrMo钢进行了高频感应钎焊连接,并分析了焊接温度、加热速度、保温电流和保温时间共16种工艺参数组合对接头显微组织和力学性能的影响规律。研究结果表明:典型接头硬质合金侧界面基本保持原始的硬质合金组织结构,主要是由WC颗粒及Co(s,s)组成,焊缝主要是由Ag(s,s)和Cu(s,s)的共晶组织组成。焊接温度对接头显微组织的影响最为显著。随着焊接温度的升高,焊缝截面的微观组织中亮色Ag基固溶体所占比例越来越小,而灰色片状Cu基固溶体所占比例越来越大。焊接温度和保温时间对接头的剪切强度影响较大,加热速度和保温电流对接头的剪切强度影响不大。接头的剪切强度随着Cu基固溶体含量的增加而升高。由于Cu基固溶体的硬度较高,其含量增加到一定程度时,接头的脆性增大,剪切强度开始降低。所有接头焊缝处的显微硬度值均稳定在210 HV左右,当焊接温度、加热速度、保温电流、保温时间增大时,焊缝中的Cu(s,s)的含量增加,焊缝的硬度值也随之增加。最优参数组合为焊接温度700℃,加热速度20℃/s,保温电流300 A,保温时间20 s,此时接头的强度达到最大值。

高速列车铜合金管路密封连接绿色感应钎焊技术研究

为解决传统火焰钎焊和高温银钎料存在的质量问题、环境污染、安全风险、成本高昂等问题,研究了一种适用于高速列车铜合金管路密封连接的绿色钎焊技术。采用低银复合钎料BAg34CuZnSn复合钎料和感应钎焊技术,对TP2Y2紫铜管套接接头进行钎焊连接,通过OM、SEM、EDS及拉伸试验等分析测试方法,分析了复合钎料感应钎焊紫铜管钎缝形貌、钎料填充深度、钎焊接头界面组织、力学性能以及钎焊热循环对紫铜管组织性能的影响。结果表明,在输出功率40 kW、钎焊电流100A和钎焊时间40 s的条件下,钎料能够完全有效填缝,实现TP2Y2紫铜管套接接头的密封和高强连接,钎缝外观光滑、连续,母材无凹陷性熔蚀。钎缝组织主要由Ag固溶体和Cu固溶体组成,钎缝组织连续致密,无气孔、裂纹等缺陷。紫铜管钎焊接头的平均抗剪强度达到222.7 MPa,能够满足大熔深铜管结构的可靠连接。

基于硬质合金/钢异质钎焊感应加热有限元仿真

【目的】为了能将感应线圈磁场聚集在硬质合金与钢基体结合处,提高加热效率,设计适用于运动连续钎焊的特殊线圈机构。【方法】根据麦克斯韦方程组和温度微分方程,建立电磁场与温度场耦合的有限元数学模型,通过有限元软件Ansys Maxwell,建立了感应线圈与焊接工件之间的电磁场-温度场耦合数学模型,计算仿真了所设计感应线圈的磁场分布强度与所焊接区域的温度场分布。【结果】利用自主研发的建工钻头钎焊设备进行大量焊接试验,通过测量焊接区域的温度,并与仿真值进行对比,验证了仿真值与实测值吻合较好。【结论】该文研究结果可为感应线圈设计、感应线圈电磁场分布研究提供理论依据,并为改进硬质工具钎焊工艺、改善钎焊区域温度场分布提供技术参考。

钛合金叶片阻尼台堆焊层铸造碳化钨颗粒分布不均匀因素分析

各类发动机转子叶片是典型的钛合金零件之一,在使用过程中,需要对发动机转子叶片阻尼台端面进行耐磨性能强化处理。而在对叶片阻尼台钎焊铸造碳化钨(WC)耐磨涂层进行强化时,铸造碳化钨(WC)颗粒分布情况将直接影响堆焊层的质量,进而影响叶片的使用寿命。为此,通过对感应钎焊原理进行分析,总结出焊接过程中铸造碳化钨(WC)颗粒分布不均匀的原因,并给出了详细的建议,供同行参考借鉴。

Physics Informed Neural Network-based High-frequency Modeling of Induction Motors

The high-frequency(HF)modeling of induction motors plays a key role in predicting the motor terminal overvoltage and conducted emissions in a motor drive system.In this study,a physics informed neural network-based HF modeling method,which has the merits of high accuracy,good versatility,and simple parameterization,is proposed.The proposed model of the induction motor consists of a three-phase equivalent circuit with eighteen circuit elements per phase to ensure model accuracy.The per phase circuit structure is symmetric concerning its phase-start and phase-end points.This symmetry enables the proposed model to be applicable for both star-and delta-connected induction motors without having to recalculate the circuit element values when changing the motor connection from star to delta and vice versa.Motor physics knowledge,namely per-phase impedances,are used in the artificial neural network to obtain the values of the circuit elements.The parameterization can be easily implemented within a few minutes using a common personal computer(PC).Case studies verify the effectiveness of the proposed HF modeling method.

Interfacial microstructure and properties of YG11C/42CrMo joint brazed with BCu64MnNi filler metal

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.

High-Frequency Induction Heating of Needle-Shaped Mg-Ferrite for Ablation Therapy of Human Cancer

For application as a novel ablation therapy of human cancer,the heating property of a needle-shaped Mg-ferrite prepared by a sintering technique was studied in a high-frequency induction field at 370 kHz.When inserted into cylindrical clay,the increase in temperature(Δ7)was 31.2℃ for the specimen with a 1.5 mm diameter,while the 1.0mm diameter specimen exhibited a ΔT value of 15.7℃ after the induction time of 1200s.The ΔT exhibited a high value of 57.9℃ during the simultaneous insertion of 3 1.5mm diameter specimens.In the computer simulation images, the relatively lower magnetic flux density and concurrent neghgibly low current density were observed from the surface to the internal regions,being different from the behavior of a ferromagnetic Ni-rod with the same size.

TC4钛合金与316L不锈钢感应钎焊接头的组织与性能

为降低钛合金与不锈钢钎焊的工艺成本与钎料成本,采用自主设计制备的Cu-Mn-Ni钎料,在低成本保护气氛氩气下对TC4钛合金与316L不锈钢进行感应钎焊,并从润湿性、接头显微组织与力学性能方面研究其可行性,揭示了界面反应的特征与机制。试验结果表明:钎料对TC4钛合金与316L不锈钢的润湿性优异,两侧接触角分别为8°、12°与6°、7°;在钎焊温度为900和930℃下保温1 min后,接头处的显微组织为TC4/(α+β)Ti/βTi/(βTi+Ti_(2)Cu)+Ti_(2)Cu/FeTi/γFe/316L;在钎焊温度为960℃下保温1 min后,显微组织为TC4/(α+β)Ti/βTi/βTi+(βTi+FeTi)/FeTi/γFe/316L;随着钎焊温度升高,接头的抗剪强度先增大后减小,钎焊温度为930℃时,保温1 min后接头的抗剪强度达到最大值155 MPa;断口分析表明316L不锈钢侧为接头的薄弱区域,断裂发生在FeTi扩散层与临近的Ti2Cu相内(900和930℃),或更厚更硬的FeTi扩散层内(960℃)。