Polymer–metal hybrid structures combine the merits of polymer and metal materials, making them widely applicable in fields such as aerospace and automotive industries. However, the main challenge lies in achieving efficient and strong connections between the metal and polymer components. This paper uses the jet electrochemical machining (Jet-ECM) method to customize the surface morphologies on 6061 aluminum alloy (AA6061) sheets. The connection between AA6061 and carbon fiber-reinforced PA66 (CF/PA66) is then achieved through hot pressure welding (HPW). The effects of aluminum alloy surface morphology, welding force, and welding time on the mechanical properties and microstructure of the joint are investigated. The optimal process parameters are determined by the design of the experiment. The results show that the aluminum alloy surface morphology has the greatest impact on the mechanical property of the welded joint. The optimal process parameters are surface morphology with wider, shallower, and sparsely distributed grooves on the aluminum alloy surface, the welding force is 720 N, the welding time is 12 s, the welding temperature is 360 °C, the cooling time is 16 s, and the optimal peak load of the joint is 6690 N. Under the optimal parameters, the fracture morphology in the AA6061 side is almost entirely covered with CF/PA66. The joint experiences cohesive failure in most areas and fiber-matrix debonding in a small area.

Electrochemical machining (ECM) is an essential non-traditional industrial shaping technology. An in-depth understanding of ECM anodic dissolution is fundamentally important for process parameter design and optimization. However, the existing electrochemical setups face challenges in achieving efficient analysis of these processes. In this work, a new flow cell has been developed via simulation-based design and 3D printing that demonstrates comprehensive advantages in terms of improved electric and flow conditions, measurement technique versatility, and production simplicity at low cost. Simulations are performed to reveal particular characteristics of the proposed cell in terms of physical distributions and to determine its key dimensions with high efficiency. The stereo lithography technique is used to realize the complex design and fabricate the proposed flow cell, thus ensuring ease of accessibility. Furthermore, the effectiveness of the developed cell is verified experimentally by examining the anodic behavior of typical metals in common ECM electrolytes, using Fe and SS304 stainless steel as examples. Test results show that information on the polarization behavior, current efficiency, anodic interface structure, and surface finish can be obtained conveniently and the results agree with previous findings, demonstrating the potential of the developed cell to perform high throughput tests to study ECM fundamentals.

Diverse industries are witnessing an increase in demand for hybrid structures of metals and carbon-fiber-reinforced thermoplastic composites (CFRTPs). Welding is an essential technique in the manufacture of metal–CFRTP hybrid structures. However, achieving high-strength metal–CFRTP welded joints faces serious challenges due to the considerable disparities in material characteristics. As an effective method to strengthen metal–CFRTP joints, surface texturing on metal is gaining significant attention. This study introduces an emerging surface texturing approach, electrochemical jet machining (EJM) using a film electrolyte jet, for enhancing the performance of AA6061-CF/PA66 hot-pressure-welded (HPW) joints. Parametric effects on surface morphology and roughness in the EJM of AA6061 are investigated. The results show that a rough surface with multiscale pores can be generated on AA6061 by EJM, and that surface morphology can be modulated by adjusting the applied current density and jet translational speed. Subsequently, the effects of different EJM-textured surface morphologies on the performance of HPW joints are examined. Surface textures created by EJM are demonstrated to significantly enhance the mechanical interlocking effect at the bonding interface between AA6061 and CF/PA66, resulting in a substantial increase in joint strength. The maximum joint strength attained in the present work with EJM texturing is raised by 45.29% compared to the joints without surface texturing. Additionally, the joint strength slightly improves as the roughness of EJM-textured surfaces rises, with the exception of rough surfaces that are textured with a combination of low current density and rapid translational speed. Overall, these findings suggest that EJM texturing using a film jet prior to welding is a potential approach for the manufacture of high-performance metal–CFRTP hybrid structures.

Nickel-based single crystal superalloys have been widely used in turbomachinery components. Electrochemical machining (ECM) is an essential method for shaping such high-performance alloys. Understanding the fundamentals of ECM for these alloys is crucial for the design and optimization of the process. This study investigated the anodic dissolution of DD6 nickel-based single crystal superalloy in concentrated NaCl and NaNO₃ electrolytes under ECM conditions. Polarization curves showed a passive-transpassive transition behavior in both electrolytes. Galvanostatic experiments demonstrated unique current efficiency characteristics contradicting the empirical ECM knowledge. Surface analysis revealed that the anomalous current efficiency of >100% in the NaNO₃ electrolyte results from the falling of γ' phases from anodic surfaces due to the preferential dissolution of the γ matrix phase. The transition from selective to uniform dissolution with increased current density and reduced electrolyte flow velocity leads to decreased current efficiency in NaNO₃ electrolyte. The removal of both γ and γ' phases depends entirely on electrochemical dissolution in NaCl electrolyte, ensuring that current efficiency maintains a normal value. A schematical anodic interface model was proposed to describe the dissolution behavior.

Aiming at the fabrication of a micro-textured surface, a novel piezoelectric-driven non-resonant elliptical vibrator is proposed in this paper; the output characteristics could be adjusted by the length change of the tool holder. The flexible mechanism is the primary structure of the vibrator, which includes a lever type mechanism, an enhanced Scott–Russell mechanism, and a T-shaped mechanism. The former two mechanisms are used to enlarge the output of the piezoelectric actuator, and the T-shaped mechanism is applied to transfer the parallel movements to the elliptical trajectory. The theoretical models including the elliptical trajectory, output stiffness, and resonant frequencies are established to investigate the impacts of the tool holder and controlling signals on the output characteristics of the vibrator, which are further validated using the finite element analysis method. A prototype is developed by integrating the non-resonant elliptical vibrator assembly and controlling system. Some experiments are carried out to verify the basic performance and the adjustable properties of the vibrator.