Search Results (44)

With the growing integration of electronic systems into modern infrastructure, the need for effective electromagnetic interference (EMI) shielding materials has intensified. This study explores the development of electroless Ni-plated fiber composites and systematically investigates the effects of post-heat treatment on their electrical, structural, and interfacial performance. Both carbon fibers (CFs) and glass fibers (GFs) were employed as reinforcing substrates, chosen for their distinct mechanical and thermal characteristics. Ni plating enhanced the electrical conductivity of both fibers, and heat treatment facilitated phase transformations from amorphous to crystalline Ni₃P and Ni₂P, leading to improved EMI shielding effectiveness (EMI-SE). NGF-based composites achieved up to a 169% increase in conductivity and a 116% enhancement in EMI-SE after treatment at 400 °C, while NCF-based composites treated at 800 °C attained superior conductivity and shielding performance. However, thermal degradation and reduced interfacial shear strength (IFSS) were observed, particularly in GF-based systems. The findings highlight the importance of material-specific thermal processing to balance functional performance and structural reliability. This study provides critical insights for designing fiber-reinforced composites with optimized EMI shielding properties for application-driven use in next-generation construction materials and intelligent infrastructure. Full article

Electroless nickel plating is a chemical deposition process in which nickel ions within a plating solution are reduced by a chemical reducing agent and subsequently deposited onto the surface of a solid substrate. Chemical nickel-plating wastewater contains substantial amounts of phosphorus as well as abundant nickel resources. In this study, electrodialysis coupled with advanced oxidation techniques was utilized for the efficient recovery of nickel and phosphorus from spent nickel-plating solutions. The end-of-life tank solution from chemical nickel plating was treated via electrodialysis to remove harmful phosphite and sulfate ions, enabling the purified solution to be reused in plating production by supplementing it with appropriate amounts of sodium hypophosphite and nickel sulfate. Subsequently, the concentrate generated from electrodialysis was treated using peroxydisulfate (PDS)-based advanced oxidation technology to break nickel complexation and simultaneously promote the oxidation of hypophosphite and phosphite ions. Finally, Ca(OH)₂ was employed as a precipitating agent to effectively recover phosphorus from the treated concentrate. From an economic perspective, optimal process conditions were determined as follows: a current density of 20 mA/cm², concentrate-to-dilute water volume ratio of 1:1, current speed of 1.0 m³/h, and a sodium sulfate concentration in concentrate of 20 g/L. Under these conditions, the migration rates of H₂PO₂⁻ and HPO₃²⁻ ions reached 67.3% and 62.53%, respectively, whereas Ni²⁺ exhibited significantly lower mobility at only 6.77%. The purified wastewater recovered approximately 60% of its initial plating activity. Regarding the concentrate—which is a by-product of electrodialysis—the hypophosphite ions were nearly completely oxidized using a PDS dosage of 0.3 mol/L. Furthermore, when the Ca/P molar ratio was adjusted to 2.0, total phosphorus (TP) and nickel (Ni) removal efficiencies exceeded 98% and 93%, respectively. Full article

As internal combustion engines (ICEs) develop towards higher explosion pressures and lower weights, their structures need to be more compact; thus, the wall thickness of their cylinder liners is reducing. However, intense vibrations in the cylinder liner can lead to coolant cavitation and, in severe cases, penetration of the liner, posing a significant reliability issue for ICEs. Therefore, research on cylinder liner cavitation has attracted increasing interest. Gray cast iron is widely used in cylinder liners for its hardness and wear resistance; however, additional surface plating is necessary to improve cavitation resistance. This study developed a novel surface-modification technology using electroless Ni-P plating combined with high-temperature heat treatment to create cylinder liners with refined grains, low weight loss rate, and high hardness. The heat-treatment temperature ranged from 100 to 600 °C. An ultrasonic cavitation tester was used to simulate severe cavitation conditions, and we analyzed and compared Ni-P-plated and heat-treated Ni-P-plated surfaces. The findings showed that the combination of Ni-P plating with high-temperature heat treatment led to smoother, more refined surface grains and the formation of cellular granular structures. After heat treatment, the plating structure converted from amorphous to crystalline. From 100 to 600 °C, the weight loss of specimens was within the range of 0.162% to 0.573%, and the weight loss (80.2% lower than the plated surface) and weight loss rate at 600 °C were the smallest. Additionally, cavitation resistance improved by 80.1%. The microhardness of the heat-treated plated surface reached 895 HV at 600 °C, constituting a 306 HV (65.8%) increase compared with that of the unplated surface, and a 560 HV increase compared with that of the maximum hardness of the plated surface without heat treatment of 335 HV, with an enhancement rate of 62.6%. Full article

A variety of NiP-TiC-SiC nanocomposite coatings were deposited to acrylonitrile–butadiene–styrene (ABS) substrates at varying plating periods and bath temperatures using electroless plating. A field emission scanning electron microscope (FESEM) demonstrates the production of various coating morphologies. Morphology analysis of the deposit coatings shows homogenous, compact, and nodular structured coatings free of any apparent defects in most deposition conditions, except at extra high-temperature deposition baths, some gas bubbles under the coating layers were seen. The patterns of X-ray diffraction (XRD) illustrate nickel peaks at 44.5 which relates to Ni (111). Energy-dispersive X-ray spectroscopy (EDX) data show that the coating’s main constituents are nickel, phosphorus, and nanoparticles. According to the results of the contact angle test, the potentiodynamic polarization, and the impedance spectroscopy (EIS) tests conducted in (3.5%) of NaCl by weight at (25 °C), the nanocomposite coating that was created at 90 min and 75 °C exhibited the best hydrophobic qualities and corrosion resistance. The coating formed at 30 min and 75 °C illustrates the best hardness value. The adhesion force was calculated using the ASTM D 3359 method (B). The findings demonstrate that the coating made under the following deposition conditions, 30 min at 75 °C, 30 min at 95 °C, and 90 min at 75 °C, produces the best bonding strength between the coating and ABS substrate (standard classification 5B); however, the complete gas bubble rejection process from the substrate is rendered difficult by deposition times longer than 30 min in a bath over 85 °C, which decreases the adhesion between NiP-TiC-SiC and the acrylonitrile–butadiene–styrene substrate. The wear rate shows a direct relationship with the coefficient of friction rather than hardness, and the coated prepared at 90 min at 75 °C offers a lower wear rate and coefficient of friction. Full article

An ultrafine-grained Al₇₁Ni_14.5Co_14.5/CNT poly-quasicrystal (QC/CNT) composite was synthesized using spark plasma sintering of powder components developed through electroless Ni-P/CNT plating of Co particles and mechanical alloying. The performance of the synthesized samples was studied using various testing methods, such as room temperature/hot compression, wear, and corrosion tests. The results were compared to the properties of alloy samples fabricated from raw and coated powders (without CNTs). The wear rate and friction coefficient of the quasicrystalline samples improved significantly due to the contribution of the CNTs. The wear rate of the CNT-containing specimens was 0.992 × 10⁻⁴ mm³/N/m, which is 47.1% lower than that of the QC sample. The positive impact of the CNTs on the corrosion potential and current density was further validated by the potentiodynamic polarization tests in a saline solution. However, these improvements in surface properties came at the cost of a 21.5% reduction in compressive strength, although the compressive strength still remained above 1.1 GPa at 600 °C. The results highlight an interesting trade-off between surface properties and mechanical strength, pointing toward the development of materials suitable for extreme conditions. Full article

Ductile iron is distinguished by its balance of mechanical properties and other advantageous characteristics, including its capacity to absorb energy. This makes it suitable for applications requiring high strength. However, its performance is impaired by its low corrosion resistance. In this study, a Ni-P coating was applied to the surface of ductile cast iron using electroless nickel plating to increase its corrosion resistance in 0.1 M NaCl. The characterization of the substrate and the coated materials was conducted using scanning electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy, and electrochemical noise. The results show that the coating deposited on a ductile iron is amorphous, compact, homogeneous, and well-adhered. The surface hardness is increased by 53%. Also, a notable increase in corrosion resistance is evidenced by the blocking effect of the coating that delimits the access of the electrolyte to the ductile iron coating. The corrosion mechanism is related to the mixed and localized corrosion phenomena for the different evaluation times. Full article

The study investigates the surface morphology of polystyrene (PS) thin films, which were crafted by drying a cast emulsion layer on a microscope glass slide. A water-in-oil (w/o) emulsion was previously formulated by dispersing a small quantity of water (or an aqueous solution) into a chloroform–PS solution containing a dissolved emulsifier (surfactant). The resultant emulsion was spin-coated onto the glass slide. Subsequently, the type and dosage of surfactant utilized played a critical role in incubating the pattern formation during solvent evaporation. Mechanistically, the surface patterns resulted from a collaborative interplay of drying-induced droplet migration/partial coagulation and surface enrichment of surfactants. Span-80 induces a collection of bowl-shaped holes with a diameter of approximately 1 µm, while AOT induces an M-shaped geometrical pattern. The holes on PS film act as a microreactor to carry out the crystallization of acrylamide, as well as the growth of Ni-P alloy dendrites by electroless plating means. Alternatively, the dispersed aqueous droplet of the emulsion was utilized to conduct in situ reduction to grow copper nanoparticles. It is also noteworthy that the patterned PS films achieved exhibit diverse glass transition behaviors, attributed to the unique interaction of surfactant and PS chains. Full article

This study reports on the use of supercritical CO₂ (scCO₂) for the metallization of ultrahigh-molecular-weight polyethylene (UHMW-PE) filaments, which are used as functional components in weavable devices. UHMW-PE is well known for its chemical and impact resistance, making it suitable for use in bulletproof clothing and shields. However, its chemical resistance poses a challenge for metallization. By utilizing scCO₂ as the solvent in the catalyzation process, a uniform and defect-free layer of Ni-P is successfully deposited on the UHMW-PE filaments. The deposition rate of Ni-P is enhanced at higher temperatures during the scCO₂ catalyzation. Importantly, the durability of the Ni-P-metalized UHMW-PE filaments is improved when the scCO₂ catalyzation is carried out at 120 °C, as evidenced by minimal changes in electrical resistivity after a rolling test. Full article

The high-temperature heat treatment of electroless nickel–phosphorus (Ni-P) coatings in an air environment, and its consequences have scarcely been investigated. This work investigated tribological characteristics of the high-temperature, heat-treated, electroless Ni-P coatings on steel substrates with low-, mid-, and high-phosphorus content for which the average phosphorus content was 2.4 wt.%, 7.1 wt.%, and 10.3 wt.%, respectively. X-ray fluorescence and energy dispersive spectroscopy were implemented to determine the phosphorus content of the coatings. The oxidation of Ni and the formation of the NiO layer on the coating surface was confirmed by the X-ray diffraction technique. A reciprocating sliding method on a ball-on-flat system was utilized to evaluate the coating’s friction and wear behavior. Among the coatings with varying phosphorus content, a high hardness of 1086 HV was found for high-phosphorus coating when heat-treated at 400 °C in an air environment, and that was decreased to 691 HV when heat-treated at 650 °C. The oxidation of nickel in the electroless Ni-P coating occurred when heat-treated at 400 °C in an air environment, and this phenomenon was increased more when the temperature was increased to 650 °C. The characteristics of the NiO layer that formed on the surface of the heat-treated electroless Ni-P coating were influenced by the concentration of phosphorus, which caused different colors of NiO to be seen on the Ni-P coating surface. A greenish black NiO layer on the low-phosphorus and black NiO layer on the mid- and high-phosphorus Ni-P coating was developed during heat treatment at 650 °C in an air atmosphere. The adhesion and tribological characteristics of the Ni-P coatings were affected by the NiO layer developed on the heat-treated Ni-P coating surfaces. The Ni-P coatings with mid- and high-phosphorus content showed enhanced wear-resistance characteristics when they underwent heat treatment in an air atmosphere at the high temperature of 650 °C. The wear volume obtained for as-plated mid-phosphorus and high-phosphorus Ni-P coatings was 0.111 mm³ and 0.128 mm³, respectively, and that was reduced to 0.031 mm³ and 0.051 mm³, respectively, after the high-temperature heat treatment. Full article

In this work, bilayer nanocoatings were designed and constructed on high-performance aromatic polysulfonamide (PSA) fibers for robust electric conduction and electromagnetic interference (EMI) shielding. More specifically, PSA fibers were first endowed with necessary electric conductivity via electroless nickel (Ni) or nickel alloy (Ni-P-B) plating. Afterward, silver electroplating was carried out to further improve the performance of the composite. The morphology, microstructure, environmental stability, mechanical properties, and EMI shielding performance of the proposed cladded fibers were thoroughly investigated to examine the effects of electrodeposition on both amorphous Ni-P-B and crystalline Ni substrates. The acquired results demonstrated that both PSA@Ni@Ag and PSA@Ni-P-B@Ag composite fibers had high environment stability, good tensile strength, low electric resistance, and outstanding EMI shielding efficiency. This indicates that they can have wide application prospects in aviation, aerospace, telecommunications, and military industries. Furthermore, the PSA@Ni-P-B@Ag fiber configuration seemed more reasonable because it exhibited smoother and denser silver surfaces as well as stronger interfacial binding, leading to lower resistance (185 mΩ cm⁻¹) and better shielding efficiency (82.48 dB in the X-band). Full article

Lattice structures are a group of cellular materials composed of regular repeating unit cells. Due to their extraordinary mechanical properties, such as specific mechanical strength, ultra-low density, negative Poisson’s ratio, etc., lattice structures have been widely applied in the fields of aviation and aerospace, medical devices, architecture, and automobiles. Hybrid additive manufacturing (HAM), an integrated manufacturing technology of 3D printing processes and other complementary processes, is becoming a competent candidate for conveniently delivering lattice structures with multifunctionalities, not just mechanical aspects. This work proposes a HAM technology that combines vat photopolymerization (VPP) and electroless plating process to fabricate smart metal-coated lattice structures. VPP 3D printing process is applied to create a highly precise polymer lattice structure, and thereafter electroless plating is conducted to deposit a thin layer of metal, which could be used as a resistive sensor for monitoring the mechanical loading on the structure. Ni-P layer and copper layer were successfully obtained with the resistivity of $8.2\times {10}^{-7}\mathsf{\Omega }\cdot \mathrm{m}$ and $2.0 \times {10}^{-8} \mathsf{\Omega }\cdot \mathrm{m}$, respectively. Smart lattice structures with force-loading self-sensing functionality are fabricated to prove the feasibility of this HAM technology for fabricating multifunctional polymer-metal lattice composites. Full article

With increasing interest in the rapid development of lattice structures, hybrid additive manufacturing (HAM) technology has become a competent alternative to traditional solutions such as water jet cutting and investment casting. Herein, a HAM technology that combines vat photopolymerization (VPP) and electroless/electroplating processes is developed for the fabrication of multifunctional polymer-metal lattice composites. A VPP 3D printing process is used to deliver complex lattice frameworks, and afterward, electroless plating is employed to deposit a thin layer of nickel-phosphorus (Ni-P) conductive seed layer. With the subsequent electroplating process, the thickness of the copper layer can reach 40 μm within 1 h and the resistivity is around $1.9\times {10}^{-8} \mathsf{\Omega }\cdot \mathrm{m}$, which is quite close to pure copper ($1.7 \times {10}^{-8} \mathsf{\Omega }\cdot \mathrm{m}$). The thick metal shell can largely enhance the mechanical performance of lattice structures, including structural strength, ductility, and stiffness, and meanwhile provide current supply capability for electrical applications. With this technology, the frame arms of unmanned aerial vehicles (UAV) are developed to demonstrate the application potential of this HAM technology for fabricating multifunctional polymer-metal lattice composites. Full article

Degradation of industrial machinery through wear can be mitigated with the deposition of protective coatings to reduce maintenance costs and prolong their service lifespans. Electroless nickel-based composite coatings is one possible method used to provide this protection. The addition of Tribaloy (CoMoCrSi alloy) particles has been found to produce composite coatings with high toughness. In this work, electroless Ni-P-Tribaloy composite coatings were plated on AISI 1018 steel substrates and subjected to low-stress abrasion tests following ASTM G65 standards to investigate the abrasion of the coating. The test was performed at 10 revolution increments, with a 45 N applied load, until coating failure was observed and the measured abrasion was reported as volume loss. The two Ni-P-Tribaloy coating samples lasted for 90 and 100 revolutions, exhibiting a wear rate of 0.170 mm³ per revolution, compared to 0.135 mm³ per revolution for the Ni-P coatings. The abrasive wear mechanism in the Ni-P-Tribaloy coating was found to be plowing of the matrix around the Tribaloy particles, followed by the removal of the particles once they are protruding, which subsequently contributes to the three-body wear of the coating. The particle removal was accelerated at the coating particle-matrix interface. It is concluded that the size of the Tribaloy is a major factor, and we recommend that further studies be carried out using finer particles to improve the wear resistance of the Ni-P-Tribaloy coating. Full article

A new lead-free electroless Ni-P plating solution was developed for the deposition of coatings with medium phosphorus content (MP, 6–9 wt%), and its composition was optimized to obtain deposits with high phosphorus (HP, 10–14 wt%). Cleaning and activation treatments were studied in terms of effectiveness and influence on the deposition rate. The concentration of reagents (nickel salt, complexing agent, reducing agent and stabilizer) was studied, and their combined effect on P content and plating rate was investigated. The obtained coatings were analyzed by SEM and XRD and thermally treated at 400 °C and 600 °C to study microstructural evolution. Vickers hardness was measured on as-deposited and annealed coatings to relate hardness evolution to microstructural changes after thermal treatments. Optimal deposition conditions were determined, enabling the production of MP coatings (6.5 wt% P) with a plating rate of 40 µm/h and HP coatings (10.9 wt% P) with a plating rate of 25 µm/h at 90 °C. Samples heat-treated at 400 °C showed improved hardness thanks to crystallization and microprecipitation of Ni₃P hard phases, whereas hardness decrease was observed after treatment at 600 °C due to the combined effect of grain growth and coarsening of Ni₃P precipitates. No through-the-thickness cracks were detected by the Ferroxyl reagent after heat treatments. Full article

In our work, we studied thin nickel films deposited by electroless plating for use as a barrier and seed layer in the through-silicon vias (TSV) technology. El-Ni coatings were deposited on a copper substrate from the original electrolyte and with the use of various concentrations of organic additives in the composition of the electrolyte. The surface morphology, crystal state, and phase composition of the deposited coatings were studied by SEM, AFM, and XRD methods. The El-Ni coating deposited without the use of an organic additive has an irregular topography with rare phenocrysts of globular formations of hemispherical shape and a root mean square roughness value of 13.62 nm. The phosphorus concentration in the coating is 9.78 wt.%. According to the results of the X-ray diffraction studies of El-Ni, the coating deposited without the use of an organic additive has a nanocrystalline structure with an average nickel crystallite size of 2.76 nm. The influence of the organic additive is seen in the smoothening of the samples surface. The root mean square roughness values of the El-Ni sample coatings vary within 2.09–2.70 nm. According to microanalysis data the phosphorus concentration in the developed coatings is ~4.7–6.2 wt.%. The study of the crystalline state of the deposited coatings by X-ray diffraction made it possible to detect two arrays of nanocrystallites in their structure, with average sizes of 4.8–10.3 nm and 1.3–2.6 nm. Full article