Papers by Keyword: Electroless Plating

Abstract: Ni-cellulose nanofiber (CNF) composite plated films were fabricated by electroless plating method. The deposition conditions and basic properties of the Ni-CNF composite film were investigated. A C1100 plate was used as the plated material, and a Ni-P electroless plating bath was prepared as the plating solution. 5 g/L of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) oxidized CNF or carboxymethyl cellulose was added to the plating solution. Sodium dodecyl sulfate (SDS) was added as a surfactant. It was confirmed that CNFs were complexed on the surface of the plated film, and the addition of SDS made CNFs disperse into the plated film. The surface of the plated film obtained by adding both TEMPO oxidized CNF and SDS had the highest Vickers hardness among all conditions investigated.

Abstract: The intrinsic hardness, high abrasive wear resistance, and corrosion properties of hard chrome coatings have resulted in their wide industrial application. However, chrome plating involves hazards associated with chrome 6+ which affect human health and drive the need to identify viable alternatives. This study investigated the addition of Cirrus alumina Dopant™ to a low phosphorus electroless nickel bath to evaluate the performance of the resulting nanocomposite coating as a potential replacement for hard chrome. A comprehensive comparison for the performance of coatings for alumina doped electroless nickel and a pure low electroless nickel coating were investigated. Results showed that Cirrus doped electroless nickel possessed a minimum hardness of 850HV_0.1, high corrosion resistance, excellent abrasive wear resistance, and a Taber Wear Index of 2.25mg/1000 cycles. These attributes suggest Cirrus Dopant™ for electroless nickel may offer an outstanding candidate to replace hard chrome coatings in many applications.

Abstract: In this study, the open-cell Mg-2Zn-0.4Y foams were prepared by infiltration casting method. The Ni/Mg hybrid foams were prepared by electroless Ni-P coating on the foam struts to improve the compressive strength and energy absorption capacity. The compressive properties of the Mg alloy foams and Ni/Mg hybrid foams were studied by quasi-static compressive test. The experimental results show that the Ni-P coating is composed of crystallites. The Ni-P coating can significantly enhance the compressive strength, energy absorption capacity and energy absorption efficiency of the foams.

Abstract: Hollow fly ash microspheres (FAMs) were successfully coated with copper (Cu) deposits via microwave (MW) irradiation. Ascorbic acid was used to reduce Cu²⁺ ions from copper sulphate pentahydrate solution. Subsequently, metallic Cu wasdeposited on FAMs within 2 to 6 min of MW irradiation. Microstructural examinations revealed that the sizes of the Cu coating on FAMs increased as MW time increased. The average approximate sizes increased from 1.56 μm to 4.04 μm as the MW processing time increased from 2 min to 6 min. Therefore, coating size could be controlled by adjusting MW irradiation time. Furthermore, EDX and XRD results confirmed the presence of Cu coating on FAMs, which agreed with the findings from the microstructural characterization. The results presented here showed that MW irradiation could be used to provide rapid and uniform heating of reactants to deposit Cu on FAMs within a short time. These Cu-coated FAMs have potential use as electrical conducting fillers in composite materials.

Abstract: Fabrication of ionic polymer metal composite (IPMC) on Si substrate and micromachining of IPMC are basic technologies for developing MEMS devices using IPMC. Adhesion of IPMC with the substrate is essential to fabricate IPMC on the substrate. Swelling of IPMC with water makes IPMC peel from the substrate due to the internal stress. To enlarge adhesion force of IPMC with the Si substrate, we have fabricated IPMC on an anodic-oxidized porous Si surface, which dramatically increased adhesion area between the IPMC and the substrate. Fabricated IPMC didn't peel from the Si substrate during the operation in water. Photolithography is a key technology in MEMS fabrication. However, water and organic solvents used in the fabrication process also swell IPMC and lower machining accuracy. We have developed a machining technology of microminiaturized IPMC by mainly using dry processes: reactive ion etching of Nafion film through metal mask, and a selective electrode formation using a plasma irradiation on Nafion and an electroless gold plating. An array of IPMCs with a width of 100 μm was fabricated and their operations in water were confirmed.

Abstract: Duplex Ni-P/Ni-P-β-SiC coatings were prepared on 2605N double phase stainless steel substrate by electroless plating process. Experiments were carried out to compare and analyze the morphologies, composition and structure of Ni-P/Ni-P-β-SiC by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), XRD and electrochemical workstation, respectively. The results show that duplex Ni-P / Ni-P-β-SiC coating has good associativity between the coating and the substrate, β-SiC particles were uniformly distributed in the coatings, without pores, crack defects and so on. When β-SiC particle concentration is 15g/L, the microhardness reached maximum 623.285HV_0.20, In addition, when the β-SiC concentration is 15g/L, the corrosion reasistence is the best.

Abstract: W–Cu (0, 0.25, 0.75, 1.5, and 3 wt.%)/Lu₂O₃ composite materials were prepared through electroless plating with simplified pretreatment method and powder metallurgy. The phases and morphologies of the W–Cu/Lu₂O₃ composites were characterized by X-ray diffraction, field emission scanning electron microscopy and energy dispersive spectroscopy. The relative density, microhardness, electrical conductivity, and bending strength of the sintered samples were examined. The experimental results show that W–Cu composites with uniform structures can be obtained with pretreated W using the simplified method, followed by electroless Cu plating. The microstructure and properties of the composites were significantly affected by the addition of Lu₂O₃ nanoparticles, resulting in high electrical conductivity and strength. The electrical conductivity of W–Cu/1.5 wt.% Lu₂O₃ composites reached 63.3%, which is higher than the national standard value of 50.71%. The bending strength of W–Cu/1.5 wt. % Lu₂O₃ reached 1306.7 MPa, which is 65.41% higher than the national standard. These results may be attributed to the uniform distribution of refined particles with Lu₂O₃ content increased to 1.5 wt. %.

Abstract: Silver-coated carbon fibers successfully fabricated by a modified electroless plating process were characterized by scanning electron microscope (SEM) and X-ray diffraction analysis (XRD). The electroless plating process was modified by replacing the conventional pretreatment and sensitization steps by only using surface hydroxylation step. And the activation and electroless plating steps were merged into one step. The silver layer was successfully coated onto the surface of carbon fibers under the given coating conditions. The effects of AgNO₃ solution concentration and reaction temperature on the conductivity of silver-coated carbon fibers were studied in detail. The results indicated that the optimum AgNO₃ solution concentration was 0.05 mol/L, and the optimum range of reaction temperature was from 45°C to 65°C.

Abstract: In this work, Pd metal layer was deposited on in-house prepared macro-porous disc alumina support by electroless plating. The in-house prepared support were repeatedly seeded for 4 cycles to obtain Pd nuclei before repeatedly electroless plated for 4 cycles. The 4-cycle Pd plating was to obtain the full layer of Pd metal observing from changing support surface from black to light grey. The plated membrane samples were annealed at 550 and 600oC for using in high-temperature H₂ separation. The annealed samples were observed morphology by SEM and confirm the occurrence of Pd layer with EDS. The SEM images revealed incomplete Pd layer. The over 4 cycles of plating were needed to form complete Pd layer since the numerous Pd ions diffused into macro-pores alumina support instead of depositing on the surface of macro-porous support. The higher annealing temperature of 600oC led to denser layer of Pd with the presence of small cracks due to the contraction of Pd particles.

Abstract: Knowing temperatures at the tool-chip interface is extremely important to optimize the machining condition and to improve the machining performance, furthermore to design high performance materials. In order to grasp the temperature distribution at the tool-chip interface, this study has devised an indexable insert with seven pairs of built-in micro Cu/Ni thermocouples on the rake face near the cutting edge. This paper shows the performance of the indexable insert with built-in micro thermocouples developed. The thickness of each element of the micro thermocouple is approximately 15 μm. The result of unsteady heat conduction analysis employing FEM shows that the temperature difference by installing the micro thermocouples is less than 10 K or 1.2 %. The temperature measurement experiments by cutting of aluminum alloy were carried out by changing the cutting speed. The results provided the evidence that the temperature distribution at the tool-chip interface can be grasped with the indexable insert with built-in micro thermocouples developed.