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Chemical plating has recently been employed for the preparation of flexible piezoresistive sensors; however, plating solutions and processes that affect the sensitivity still need further exploration. In the study, a sponge-based flexible sensor with copper as its conductive material is prepared using electroless plating. The variation in sponge resistance and sensitivity changes with different plating times are studied. It is found that, with the increasing plating time, the conductivity increases and the resistance of sample will decrease. Moreover, the range of resistance difference will decrease under compression, thus the sensitivity decreases. Furthermore, the sensor’s applications were assessed, verifying the practicability of the developed preparation method. This study may bring ideas for the new development of flexible pressure sensors.

Electroless plating in micro-channels is a rising technology in industry. In many electroless plating systems, hydrogen gas is generated during the process. A numerical simulation method is proposed and analyzed. At a micrometer scale, the motion of the gaseous phase must be addressed so that the plating works smoothly. Since the bubbles are generated randomly and everywhere, a volume-averaged, two-phase, two-velocity, one pressure-flow model is applied. This fluid system is coupled with a set of convection–diffusion equations for the chemicals subject to flux boundary conditions for electron balance. The moving boundary due to plating is considered. The Galerkin-characteristic finite element method is used for temporal and spatial discretizations; the well-posedness of the numerical scheme is proved. Numerical studies in two dimensions are performed to validate the model against earlier one-dimensional models and a dedicated experiment that has been set up to visualize the distribution of bubbles.

Voids in electroless copper (Cu) plating layers critically influence the reliability of microvias in high-density interconnect (HDI) packaging substrates. This study investigates void formation mechanisms by fabricating multilayered Cu structures that simulate microvia interconnections and performing electroless Cu plating under controlled nickel (Ni) ion concentrations and bath temperatures. Void morphology and distribution are analyzed using transmission electron microscopy (TEM) and quantitative image analysis. The results reveal that increased Ni content and elevated bath temperatures accelerate the plating rate, thereby promoting void formation at the initial stage of deposition. Theoretical analysis suggests that this behavior is driven by surface cohesion forces acting on nascent voids. A void growth mechanism is proposed, wherein voids predominantly originate within the initial Cu layer due to localized hydrogen accumulation near palladium (Pd) catalysts. In contrast, subsequent layers—deposited after Pd sites are buried—exhibit reduced maximum (max.) void sizes and lower void fractions. These findings provide mechanistic insight into void evolution in electroless Cu layers and underscore the critical role of Ni content and bath temperature in enhancing HDI packaging substrate reliability.

Titanium alloys are widely used in many industrial applications, from aerospace to automotive, and from defense to medical, as they combine superior properties such as high strength and low density. Still, titanium and its alloys are insufficient in environments with friction and wear because of their weak tribological properties. In the literature, numerous research works on improving the surface quality of titanium alloys have been conducted. Electroless coatings, on the other hand, are one of the most widely used surface improvement methods due to its homogeneous thickness achievement, high hardness, and good corrosion resistance. The autocatalytic reduction in the coating process enhances the surface quality of the material or alloy considerably. In addition, many studies in the literature aim to carry the properties of electroless coatings to a higher point by creating a composite coating with the addition of extra particles. In this study, graphene-reinforced nickel matrix Ni-P-Gr coating was applied to the surface of Ti-6Al-4V alloy, in order to enhance weak tribological behaviors, by the electroless coating method. Moreover, the coated and uncoated, heat-treated, and non-heat-treated specimens were subjected to abrasion in linear reciprocating ball-on-plate configuration to observe tribological properties. Microstructure examination of the samples was performed using a scanning Electron Microscope (SEM), X-ray Diffractometer (XRD), X-ray Photon Spectrometry (XPS), and Raman Spectroscopy. Specific wear rates of specimens were calculated using microstructural analysis and the hardness of the produced samples was measured using the Vickers hardness test. Results indicate that both the coating and the heat treatment improved the microstructure and tribological properties significantly. With the graphene-reinforced Ni-P coating via electroless coating process, the hardness of the substrate increased by about 34%, while it increased by approximately 73% using subjected heat treatment. Furthermore, the wear rate of the Ti-6Al-4V substrate was approximately 98% higher than that of the heat-treated nanocomposite coating. The highest wear resistance was obtained at the heat-treated nanocomposite coating.

Electroless coating brings the advantage of providing films on the complex geometry of additively manufactured components. However, there is a knowledge gap about the impact of AM part surface and postprocessing parameters on the quality of electroless coating. This study explores the application of three solution-based surface finishing techniques on the microstructure and surface hardness of additively manufactured stainless steel components coated with electroless nickel films. Given that AM techniques for metal parts often yield surfaces with inherently rough textures and differences in properties along the different planes, we investigated their relationship with nickel coating. To mitigate the impact of surface irregularities on electroless nickel coating quality, this research evaluated the effectiveness of chemical polishing (CP) and Electropolishing (EP) as post-processing treatments for AM stainless steel. Characterization of the treated samples was conducted using the analytical Digital Microscope, Scanning Electron Microscope (SEM), and scratch tester. Additionally, the study incorporated an instant segmentation machine learning algorithm to overcome image analysis challenges. The findings indicate that EP and CP significantly improve surface smoothness, decreasing the arithmetical mean height (Ra) by as much as 4 µm and 10 µm, respectively. Furthermore, the nickel-coated AM samples demonstrated an enhancement in scratch resistance, exhibiting up to a two-fold increase in surface hardness compared to their as-built counterparts. Taguchi design of the experiment was applied to investigate the effect of process parameters. This study provides insights for developing improved surface quality and acquiring new properties via the coating process to make AM parts suitable for challenging environments and novel applications.

Hydroxamic acid extractants, such as LIX984, demonstrate high efficiency in extracting nickel from electron-free nickel waste solutions; however, they suffer from a slow extraction rate. This study investigated the effect of adding 2–5 vol.% of three organophosphate extractants (P507, P204, and Cyanex272) to LIX984. The results show that incorporating 2–5 vol.% of P507 or Cyanex272 significantly improves both extraction efficiency and kinetics. The addition of organophosphate extractants increased the extraction rate by 1.5–10 times, indicating a direct correlation between the extractant content and the acceleration of the extraction process, with higher concentrations yielding faster extraction. Compared to the use of LIX984 alone, where nickel extraction efficiency was only 46%, the addition of 5 vol.% P507 increased efficiency to over 99%, with a substantial improvement in extraction rate. Similarly, 2 vol.% P204 achieved a nickel removal efficiency of 99.8%. In non-electroplating waste solutions (pH 4–6), selective removal of iron and zinc impurities was achieved by first adding 2–5 vol.% P204 or P507, followed by adjusting the pH to 6–7 and using a mixture of organophosphate extractants. The spent electroless nickel plating baths were then treated with LIX984 combined with organophosphoric acid extractants, yielding nickel salt solutions of higher purity. Thus, P507, P204, and Cyanex272 serve as effective promoters for the hydroxamic acid extractant LIX984, resulting in both enhanced nickel extraction efficiency and faster extraction kinetics.

The Ti-Zr and Ti-Zr/sol-gel were used as pretreatment layers before the electroless nickel coating on AM60B magnesium alloy. Scanning Electron Microscopy was employed to investigate the surface morphology of the pretreated layers and applied electroless coatings. Chemical analysis of the Ti-Zr layer, and nickel coatings was done using the Energy-Dispersive X-ray Spectroscopy. Moreover, the X-ray Diffraction and Atomic Force Microscopy methods were utilized to evaluate the microstructure and surface roughness of the electroless coatings, respectively. Electrochemical Impedance Spectroscopy was employed to study the corrosion behavior of Ni-P coatings. The results show that Ti-Zr layer has structural cracks, and the sol-gel film was covered all cracks entirely. The cauliflower-like electroless nickel coating was applied on both mentioned pretreated layers. The cross-sectional images revealed the higher thickness for the electroless coating on Ti-Zr/sol-gel layer, probably due to a large number of Ni nucleation centers. The EIS results demonstrate that the electroless coating on Ti-Zr/sol-gel has high corrosion protection and microhardness value.

In the field of Precision Glass Molding (PGM), binderless tungsten carbide (WC) is a pivotal material for molds, despite its high processing costs and complexities. Nickel-phosphorus (Ni-P) alloys also exhibit superior performance at elevated temperatures. The innovation of Ni-P/WC composite molds addresses the issue of the poor machinability of WC. This research delves into the influence of the activating solution’s concentration on the surface activation energy of WC, the quality of plating, and the deposition rate during the electroless Ni-P plating process. Additionally, the study scrutinizes how the pH level of the plating solution impacts the quality of Ni-P, the rate of deposition, and the phosphorus content. These investigations have led to the realization of an efficient and high-quality Ni-P plating process for WC.

This paper describes a low-temperature metallization and laser trimming process for microwave dielectric ceramic filters. The ceramic was metalized by electroless copper plating at a temperature lower than those of conventional low-temperature co-fired ceramic (LTCC) and direct bond copper (DBC) methods. Compared with filters made via traditional silver paste sintering, the metal in the holes of the microwave dielectric filters is uniform, smooth, and does not cause clogging nor become detached. Further, the batches of fabricated filters do not require individual inspection, reducing energy, labor, cost, and time requirements. A microwave dielectric filter was then manufactured from the prepared ceramic using a laser trimming machine with a line width and position error within ±50 μm; this demonstrates a more accurately controlled line width than that offered by screen printing. After using HFSS software simulations for preliminary experiments, the microwave dielectric filter was tuned to a target Wi-Fi band of 5.15–5.33 GHz; the return loss was <−10 dB, and the insertion loss was >−3 dB. To implement the real-world process, the laser parameters were optimized. Laser trimming has a higher success rate than traditional manual trimming, and the microwave dielectric filter manufactured here verified the feasibility of this process.

Electroless nickel plating technology displays exuberant vitality in the field of surface treatment, nevertheless accompanying with its spent plating solution for environmental pollution and resource waste. Therefore, it is of great significance how to realize the high efficient utilization of various waste ions in the electroless nickel plating wastewater (ENPW). Herein, after transforming nickel and sulfur elements in ENPW into nickel hydroxide and barium sulfate, the remaining elements serve as primary raw materials for the synthesis of multi-porous multi-doped nano-Na 3 V 2 (PO 4 ) 3 @C materials (D-NVP). This is achieved by integrating the sol–gel method with the carbon thermal reduction method. The as-synthesized D-NVP displays a 3D porous skeleton structure, where the pores with different nano-micron sizes are interlinked by the skeletons with the thickness of 40–200 nm. The unique structure, combined with Mg-Ca-Fe doping, contributes to D-NVP’s excellent electrochemical properties, with the initial discharge capacities of 108, 107, 104.3, 101.5, 98.6, and 95.3 mAh·g −1 at 0.2, 0.5, 1, 2, 5, and 10 C, and the capacity retention rates of 99.2% and 98.9% at 1 and 5 C after 200 cycles, respectively.