Microstructure and Properties of Fe-Based Coating on Column Surface Formed by High Frequency Induction Cladding

The Fe-based coating was produced on the surface of the column substrate with a Al2O3 cylindrical sleeve by high frequency induction cladding, microstructure of the coating was investigated with scanning electron microscope (SEM), the crystal structure was characterized by X-ray diffractometer (XRD), the microhardness and wear resisitance of the coating were evaluated. The results show that a metallurgical bond between coating and substrate was obtained during the rapid solidification, the phases of the coating were composed of austenite and the eutectic of γ-Fe + (Cr, Fe)7(C, B)3. Compared with the substrate, the microhardness and wear resistance of the coating improved apparently, solid-solution strengthening and second-phase particle hardening led to these results.

Temperature field evolution and heat transfer during continual local induction cladding

The evolution of temperature field of the continual motion induction cladding and the depth of heat affected zone are studied in this study.A three-dimensional finite element model for the point type continual induction cladding is established to investigate temperature distributions of fixed and motion induction cladding modes.The novel inductor is designed for cladding of curved surfaces.The modeling reliability is verified by the temperature measurements.The influence of process parameters on the maximum temperature and the generation and transfer of heat are studied.Quantitative calculation is performed to its melting rate to verify the temperature distribution and microstructures.The results show that a good metallurgical bond can be formed between the cladding layer and substrate.The melting rate gradually falls from the top of the cladding layer to the substrate,and the grain size in the substrate gradually rises.The heat affected zone is relatively small compared to integral heating.

Study on GNi-WC25 Coating by High Frequency Induction Cladding

Process and mechanism of high frequency were studied in this paper by means of cold attachment for the preparation of GNi WC25 coating . The results show its special distribution law of eddy current while the magnetic transition temperature and electric resistivity of the coating have been measured .Wear resistance of the high frequency induction coating has an advantage over those of laser cladding coating and oxygen acetylene spraying fusing coating . Moreover , the GNi WC25 coating by high frequency induction cladding has smooth surface and even microstructure.

Effect of Fe content on microstructure and mechanical properties of Cu-Fe-based composite coatings by laser induction hybrid rapid cladding

To select the proper composition and obtain an overall material?microstructure?property relationship for Cu?Fe alloy, theeffect of Fe content on microstructure and properties of Cu?Fe-based composite coatings by laser induction hybrid rapid claddingwas investigated. Microstructure characterization of the composite coatings was tested utilizing SEM, XRD and EDS. Microhardnessmeasurement was executed to evaluate the mechanical properties of the composite coatings. The results show that for low Fe content,the composite coating presents a feature that Fe-rich equiaxed dendrites are embedded in the Cu-rich matrix. With increasing Fecontent, the Fe-rich particles are dispersed in the Cu-rich matrix. With further increasing Fe content, large amounts of Cu-richparticles are homogeneously dispersed in the interdendrite of the Fe-rich matrix. Correspondingly, the average microhardness of thecomposite coatings increases gradually with the increase of Fe content and the microhardness of Cu14.5Fe83Si2C0.5 coating is muchtwice higher than that of the substrate.

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.

Interface characteristics of Al_2O_3－13%TiO_2 ceramic coatings prepared by laser cladding

Al2O3-13%TiO2 （mass fraction） coatings, prepared by laser cladding on nickel-based alloy, were heated using high frequency induction sources. The coating microstructure and the interface between bond coating and ceramic coating were characterized by SEM, XRD and EDS. The results show that two-layer substructure exists in the ceramic coating： one layer evolving from fully melted region where the sintered grains grow fully; another layer resembling the liquid-phase-sintered structure consisting of three-dimensional net where the melted Al2O3 particles are embedded in the TiO2-rich matrix. The mechanism of the two-layer substructure formation is also explained in terms of the melting and flattening behavior of the powders during laser cladding processing. The spinel compounds NiAl2O4 and acicular compounds Cr2O3 are discovered in the interface between bond coating and ceramic coating. It proves that the chemical reactions in the laser cladding process will significantly enhance the coating adhesion.

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.

高频感应熔覆NiTiFe合金涂层摩擦学性能研究

为增强金属材料表面的耐磨性能,采用高频感应熔覆技术,在HT300基底表面制备出NiTiFe合金涂层;利用扫描电子显微镜(SEM)、能谱仪(EDS)、显微硬度计和X射线衍射仪(XRD)对NiTiFe合金涂层的微观组织、元素组成、硬度、相组成和与基底的结合情况进行表征与分析;通过摩擦磨损试验机对涂层的摩擦学性能进行测试,对其摩擦磨损机制进行分析。结果表明:涂层组织致密,无裂缝和空隙,成型质量良好,平均厚度达到0.7 mm,与HT300基底实现了冶金结合;涂层中主要包含Fe2Ti、Fe6.94Ti0.36和Ni3Fe三种相,Fe元素的加入使涂层的晶格发生畸变,硬度提高,平均硬度达到997.36HV,约为HT300基底平均硬度值的5倍。通过摩擦磨损试验发现,试验前期,NiTiFe合金涂层与对摩副之间的摩擦因数较低,维持在0.2左右,对摩副的失效导致摩擦副之间的接触形式发生改变,摩擦因数产生阶跃;随着载荷的增加,涂层上呈现的磨痕宽度在不断增加,对摩副由于磨损造成的材料去除后暴露出的面积也在不断增大。摩擦磨损试验后,NiTiFe合金涂层摩擦表面光滑平整,仅出现了轻微的磨粒磨损,磨损体积远小于对摩副,表现出优良的耐摩擦磨损性能。

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.

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.

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.

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.

感应熔覆过程中氧化皮对锅炉管内壁力学性能的影响及其抑制技术研究

高频感应熔焊技术代表了锅炉四管受热面高温防腐技术的发展方向。但由于高频感应线圈对管外壁涂层加热重熔时,管内壁也随之被加热,使管内壁表面产生氧化皮。通过检测表面硬度和脱碳层深度等指标,对于氧化皮对管内壁性能的影响进行了评估。结果表明:当重熔温度升高使得管内壁温度超过580℃时,由管内壁基体表面起向外依次排列为FeO、Fe3O4、Fe2O3等三层氧化膜,厚度比约为1∶10∶100。FeO虽然较薄但结构疏松,晶格缺陷多,不稳定易分解,易从管内壁表面脱落,是造成爆管事故的主要因素。利用氮气保护的方法对感应重熔过程产生的氧化皮进行了有效抑制,该方法也抑制了管排背面氧化皮的产生,实验证明其效果显著。

感应熔覆原位自生TiC增强钛基复合涂层的纳米力学性能

为揭示感应熔覆原位TiC/Ti复合涂层微观结构与力学性能的对应关系,利用单一纳米压痕测试方法研究涂层内不同相结构的纳米力学性能变化规律,利用点阵压痕测试方法研究涂层微区结构的力学性能。单一压痕结果显示原位TiC增强相的纳米压痕硬度和弹性模量分别为21.3 GPa和275 GPa,富α-Ti与富β-Ti区域的基质相平均纳米硬度分别为4 GPa和6 GPa,平均弹性模量分别为130 GPa和155 GPa。点阵压痕与单一压痕测试结果之间具有较好的对应关系,对点阵纳米压痕测试结果进行三峰高斯拟合得到的最小峰值代表了涂层基质相的力学性能,中间峰值反映涂层的综合力学性能,最大峰值因受增强体尺寸与压痕位置的影响低于原位TiC增强体的真实力学性能。在考虑涂层微观结构与增强体尺寸的情况下,通过合理设置点阵压痕测试条件,选择适当的测试区域,可以在获得原位钛基复合涂层不同相结构真实力学性能的同时,揭示涂层的综合性能。

感应熔覆技术研究现状及发展

机械零件长期在高温、潮湿以及交变载荷等恶劣环境下工作,会导致机械设备出现可靠性降低和服役寿命缩短等问题。因此,对零件表面性能提出了高耐磨性和高耐腐蚀性等严苛要求。在此背景下,感应熔覆技术作为绿色表面改性工艺,因其成本低、效率高、热影响区小及熔覆质量好等特点而被广泛应用于机械零件表面强化领域。首先,简述了感应熔覆技术的工作原理和特点,重点探讨了自熔性合金粉末和添加陶瓷及稀土元素合金粉末的应用效果和潜在优势;其次,介绍了感应熔覆技术的工艺流程,分析了预制涂层、保护套筒以及其他强化工艺对感应熔覆涂层性能和质量的影响,指出敏感性参数是影响感应熔覆涂层成形和传热的重要因素;最后,概括了感应熔覆数值模拟方法的发展现状和存在的问题,并针对感应熔覆成形过程和传热机制的发展提出了相关建议。在此基础上,对感应熔覆增材制造过程中的关键科学问题和技术难题进行了展望并提出了未来的研究方向。通过研究新材料及采用新型数值模拟技术,为优化工艺参数和开发新型涂层提供更加精确的指导。

小弯曲半径双金属冶金复合管热弯变形分析

针对X65+Inconel625双金属冶金复合弯管尤其是小弯曲半径容易出现耐蚀层开裂的问题,采用有限元方法进行热弯变形分析,确定弯制工艺并进行试制,对冶金复合弯管不同位置取样进行工艺评定试验,试验项目包括外观尺寸、无损探伤、堆焊层稀释率检、压塌/压扁试验、硬度试验、剪切试验、拉伸试验、冲击试验、金相检测、腐蚀试验堆焊层腐蚀试验,以及晶间腐蚀试验等,结果表明,冶金复合弯管力学性能优良、尺寸稳定、无缺陷,金相组织稳定,堆焊层防腐性能良好。

高中频感应熔涂Ni60涂层组织分析

分析了高频、中频感应熔涂Ni60涂层的显微组织。结果表明,高频感应熔涂Ni60涂层与基体形成了良好的冶金结合,在涂层与基体之间存在明显的扩散转移层。高频感应熔涂涂层组织均匀细致,有丰富的增强耐磨性的硬质相。相比之下,中频感应熔涂涂层基本上均为针状组织,形成贫铬区倾向较大。

激光熔覆与激光-感应复合熔覆WC-Ni60A涂层的结构与性能特征

对单纯激光熔覆与激光-感应复合熔覆Ni60A+35%WC涂层的几何外形、稀释率、WC颗粒分布、显微组织与抗干滑动磨损性能进行对比分析。结果表明,单纯激光熔覆的最大激光扫描速度与最大送粉量仅为600 mm.min–1与25 g.min–1,当激光-感应复合熔覆采用相同的工艺参数时,复合熔覆层的宽度、热影响区、稀释率均大于单纯激光熔覆层,厚度却小于单纯激光熔覆层,WC颗粒与析出的碳化物不均匀地分布于复合熔覆层内,复合熔覆层的抗干滑动磨损性能比单纯激光熔覆层的差。但是,激光-感应复合熔覆的最大激光扫描速度可以提高到2 200 mm.min–1,最大送粉量可以提高到75.6 g.min–1,加工效率是单纯激光熔覆的3倍多,复合熔覆层内WC颗粒分布均匀,经检测无裂纹且稀释率仅为5.2%,抗干滑动磨损性能约是单纯激光熔覆层的1.42倍。

Q235钢表面金属陶瓷涂层熔覆技术的研究进展

综述了近年来Q235钢表面金属陶瓷涂层制备技术的研究进展,重点介绍了常见的金属陶瓷涂层制备方法如氩弧熔覆、感应熔覆、等离子熔覆、激光熔覆等及其存在的问题,展望了今后的发展方向。

高频感应熔涂、激光熔覆与氧乙炔喷焊GNi-WC25涂层的性能研究

对比三种不同工艺(高频感应熔涂、激光熔覆、氧乙-炔喷焊)制得的GNi-WC25涂层的性能。结果表明,高频感应熔涂GNi-WC25涂层的表层硬度、耐磨性和耐腐蚀性均优于激光熔覆涂层和氧乙炔喷焊涂层,而且高频感应熔涂涂层表面平整,后续加工量较少。