A hybrid nanofluid-ultrasonic assisted synergistic process is proposed to attain excellent surface quality and be applied to aerospace ceramic products. Through the utilization of molecular dynamics approaches, heat transfer and wetting models of Al2O3/GO nanofluids were developed to disclose the evolution of the thermal properties. Moreover, the tribological properties were characterized, and synergistic grinding of Al2O3 ceramics and fiber reinforced composite ceramics SiO2f/SiO2 were conducted. The results show that the nanofluid reaches dispersion equilibrium and suspension stability under ultrasound, thus ensuring the optimal immediate processing performance. The nanofluid- ultrasonic assisted synergistic grinding effectively reduces cutting temperature and force, prevents the occurrence of surface defects and enhances integrity when compared with single improvement processes or traditional methods.
Composites, owing to their outstanding properties such as lightweight and high strength, have become a vital material foundation for the lightweight design of high-end equipment. However, their reliable connection, particularly in hybrid structures involving thermoplastic composites (TPCs), thermoset composites (TSCs), and metals, remains a key bottleneck limiting their engineering applications. Ultrasonic welding, offering advantages such as high efficiency and low thermal damage, represents a promising solution. Nevertheless, the technology still lacks systematic theoretical understanding regarding the synergistic mechanisms of multiple process parameters, the fundamental differences in interface reconstruction strategies, and the long-term service performance of welded joints. This review addresses these three core issues by summarizing recent research advances in the field of ultrasonic welding of composites. The results indicate that strong coupling interactions exist among process parameters, exerting nonlinear influences on joint performance. In terms of interface reconstruction, different material systems follow fundamentally different design logics: for TPC/TPC welding, the function of energy directors (EDs) relies on geometric design to alter the micromechanical boundary conditions at the interface, thereby achieving spatial redistribution of the heat source; for TPC/TSC welding, a coupling layer (CL) is essential to activate the originally non-fusible cured surface, transforming it into a weldable interface while suppressing thermal damage to the thermoset resin; whereas TPC/metal welding requires the synergistic combination of physical interlocking and chemical bonding. Moreover, interface reconstruction strategies directly determine the long-term reliability of joints in complex service environments. This review establishes a comprehensive knowledge framework encompassing process parameters, interface engineering, and service performance, identifies current research gaps, and provides a systematic reference for deepening the mechanistic understanding and promoting the engineering application of ultrasonic welding technology for composites.
Nickel‑titanium-based (Nitinol) shape memory alloys (SMA) possess unique properties, including superelasticity and shape memory effect, which make them suitable for next-generation biomedical implants. The micro-electrical-discharge (μ-ED) milling process is an excellent machining process used for making complex features in Nitinol SMA. In this investigation, microchannels were fabricated on Nitinol SMA by μ-ED milling process using different sustainable dielectrics, namely sunflower, sesame, and canola oil. The performance of the sustainable vegetable oils was compared with the synthetic EDM oil to find an alternative eco-friendly dielectric, considering the machining performance in terms of material removal rate (MRR), tool wear rate (TWR), and dimensional accuracy coupled with biocompatibility and antibacterial characteristics of the fabricated microchannels. The experimental findings revealed that canola oil is a viable alternative to the conventional dielectrics because of achieving fair MRR and TWR among the chosen vegetable oils. The fabrication of microchannels with canola oil resulted in achieving a higher MRR of 0.09257 g/min and a moderate TWR of 0.00318 g/min as compared with EDM oil, which had the lowest MRR of 0.06153 g/min and highest TWR of 0.00438 g/min. The minimum deviation and taper and the maximum depth of the microchannel were also achieved with the canola oil. The cytotoxicity analysis confirmed the highest cell proliferation rate of 92.79% for the microchannels fabricated using canola oil, while microchannels fabricated using EDM oil showed the lowest cell proliferation rate of 57.85%. The antibacterial analysis showed negligible bacterial growth on the surface of the microchannels fabricated using the different types of vegetable oils. The morphological analysis showed damaged cell structures of the bacteria chosen for the antibacterial test, indicating a superior antibacterial nature of the surface of the microchannels fabricated using the vegetable oils, which is favourable for biomedical applications.
In ultrasonic welding of thin Al/Cu dissimilar joints, non-uniform interfacial deformation can cause under-welding at insufficient energy and excessive local damage as the energy input increases, thereby narrowing the available processing window. To address this, a novel composite horn—integrating a hemispherical base with a bullet-shaped tip—was developed to improve the interfacial bonding of 1060 Al foil/T2 Cu strip joints. Its performance was compared with that of conventional pyramidal and hemispherical horns across a welding energy range of 100–800 J. Systematic characterization showed that the composite horn maintained comparatively high and stable linear strength across the investigated energy range of 100–800 J, indicating a wider energy processing window. Notably, at 800 J, the composite horn achieved the highest average linear strength of 37.7 N/mm, surpassing the hemispherical and pyramidal horns by 33.7% and 40.1%, respectively. Furthermore, it exhibited the largest apparent bonded length (582 μm) and a comparatively uniform apparent AlCu elemental transition zone. EBSD analysis revealed a continuous grain-refined layer and a comparatively uniform local misorientation distribution in the composite-horn joint. These findings show that the proposed composite horn provides a favorable balance between localized deformation and bonding uniformity, offering a promising tool-design strategy for high-quality ultrasonic welding of thin dissimilar metals.
Grain refinement by severe plastic deformation is an effective approach for improving the performance of metallic materials. However, its influence on the ultraprecision machining behavior of commercially pure titanium (CP-Ti) remains unclear. In this study, TA2 CP-Ti specimens with different grain sizes were fabricated by equal-channel angular pressing (ECAP). The microstructural evolution and its effects on ultraprecision machining performance were systematically investigated. The results show that the average grain size was refined from approximately 10 μm to 1.3 μm after 16 ECAP passes. Meanwhile, continuous dynamic recrystallization, assisted by dislocation slip and deformation twinning, was identified as the primary grain-refinement mechanism, leading to enhanced hardness and compressive strength due to combined strengthening effects. Ultraprecision machining experiments reveal that the cutting force increases with decreasing grain size, whereas the machined surface roughness decreases under identical cutting conditions. This behavior is attributed to the dual effect of grain refinement: the increased grain-boundary density enhances the resistance to plastic deformation, while the more homogeneous ultrafine-grained microstructure promotes stable material flow and suppresses localized deformation. These findings establish a direct relationship between ECAP-induced microstructural evolution and ultraprecision machining performance, providing guidance for the microstructural design and precision manufacturing of titanium-based components.
