Voronoi tessellations are shown to be statistically representative of polycrystalline microstructures, which have been widely accepted for the modeling of microstructures of metallurgic and ceramic materials. In this paper, a new implementation of the Voronoi diagram in Laguerre geometry is presented for the generation of numerical models of polycrystalline microstructures, where the size and shape of the grains can be controlled, and the 3D grain boundaries can be modeled with a specified thickness. The distribution of grain sizes in the models is fitted to a lognormal distribution, compared with the normal distribution in the Voronoi tessellation methods. Finally, statistical analyses of grain face and grain size distribution are performed with the models, and the macroscopic elastic properties of polycrystalline ceramic materials are simulated to verify the capability of the presented method.

Jet electrochemical machining (Jet-ECM) is a significant prospective electrochemical machining process for the fabrication of micro-sized features. Traditionally and normally, the Jet-ECM process is carried out with its electrolytic jet being vertically impinged downstream against the workpiece. Therefore, other jet orientations, including a vertically upstream orientation and a horizontal orientation, have rarely been adopted. In this study, three jet orientations were applied to electrolytic jet machining, and the effect of jet orientations on machining characteristics was systemically investigated. Horizontal jet orientation is of great benefit in achieving accurate micro-sized features with excellent surface quality with either a static jet or a scanning jet for the Jet-ECM. On the other hand, the Jet-ECM with a horizontal jet orientation has a smaller material removal rate (MMR) than the ones with vertical jet orientations, which have almost the same MMR. It was found that an enhancement of machining localization and a reduction of MMR for horizontal jet electrochemical machining primarily results from an improvement of the mass-transfer field. The horizontal orientation of the jet is beneficial for the Jet-ECM processes to improve machining accuracy.

The replacement of gold bonding wire with silver bonding wire can significantly reduce the cost of wire bonding. This paper provides a comprehensive overview of silver wire bonding technology. Firstly, it introduces various types of silver-based bonding wire currently being studied by researchers, including pure silver wire, alloy silver wire, and coated silver wire, and describes their respective characteristics and development statuses. Secondly, the development of silver-based bonding wire in manufacturing and bonding processes is analyzed, including common silver wire manufacturing processes and their impact on silver wire performance, as well as the impact of bonding parameters on silver wire bonding quality and reliability. Subsequently, the reliability of silver wire bonding is discussed, with a focus on analyzing the effects of corrosion, electromigration, and intermetallic compounds on bonding reliability, including the causes and forms of chlorination and sulfurization, the mechanism and path of electromigration, the formation and evolution of intermetallic compounds, and evaluating their impact on bonding strength and reliability. Finally, the development status of silver wire bonding technology is summarized and future research directions for silver wire are proposed.

Enabling metallic surfaces to possess broad-spectrum self-cleaning functions is one of most active research topics. In this paper, a composite electrodeposition process is adopted to prepare multifunctional self-cleaning metallic surfaces by introducing tungsten trioxide (WO₃) nanoparticles and carbon nanotubes (CNTs) into the deposited nickel metal, forming the Ni/nano-WO₃/CNTs metal matrix composite (MMC) coating. Preparation parameters and conditions are optimized experimentally in terms of the dispersed phase fraction in the MMC coating and the surface microstructures feature. Wettability, mechanical properties, and self-cleaning functions of the MMC coating are evaluated. It was found that the MMC coating shows a unique micro- & nano-scale dual hierarchical surface structure with overhanging microstructures, being superhydrophilic in its as-plated state and superamphiphobic after it being modified; the as-plated MMC coating exhibits an excellent photocatalytic degradation ability and a broad antibacterial performance for the synergistic decomposition effects of nano-WO₃ and CNTs; the modified MMC coating is able to maintain a vigorous superhydrophobicity during thermal shocks, long-distance abrasion, and dozens of time adhesions; both the as-plated and the modified MMC coating are significantly resistant to pollution. The Ni/nano-WO₃/CNTs MMC coating surface possesses transferable extreme wettability and thus shows broad-spectrum anti-fouling and antibacterial properties as well as good mechanical durability.

Kerosene-submerged jet electrochemical machining (Jet-ECM) is a nontraditional high-accuracy Jet-ECM developed recently in which the jet nozzle and workpiece are both submerged inside the kerosene. In this paper, to further enhance the machining accuracy and tap the potential of the kerosene-submerged Jet-ECM, a modified version was proposed. In the modified version, the jet is impinged horizontally instead of vertically against the workpiece surface. Numerical simulations were carried out to elucidate the flow field distribution characteristics within the inter-electrode, and the influence of relevant factors including jet orientation, nozzle size, working gap and applied voltage on the machining localization and surface quality of the machined microstructures were investigated. It was found that, compared with the kerosene-submerged vertical Jet-ECM, the horizontal Jet-ECM is able to achieve improved machining localization, geometric dimension consistency and surface quality both in the static machining mode and in the scanning machining mode. The primary reasons are: the horizontal orientation of the jet considerably reduces re-contact of the reflected electrolyte with the outside wall of the used metallic nozzle, thereby reducing stray corrosion significantly; such jet orientation also facilitates the removal of the electrolytic products from the machining area because of the gravity effects, thus improving mass transfer condition and stabilizing the machining process.