Microstructure and electromagnetic interference shielding effectiveness of electroless Ni–P plated polyester fabric

Microstructure and electromagnetic interference shielding effectiveness of electroless Ni–P deposits obtained from an alkaline hypophosphite reducing electroless nickel bath was studied. The effects of plating temperature on the deposition rate, surface morphology, chemical composition and structure of the electroless Ni–P deposits were investigated. Surface resistance and electromagnetic interference (EMI) shielding effectiveness (SE) of Ni–P plated polyester fabric were also evaluated. The results demonstrated electroless Ni–P plated polyester fabric present useful EMI shielding materials.     

Microscopic and macroscopic models of photo-induced volume changes in amorphous selenium

Electroless copper plating of polyester fabrics was demonstrated in the present investigation. The electroless Cu plating process on polyester fabric was modified by replacing the conventional PdCl₂ activator with an AgNO₃ activator to reduce the overall cost of the plating process. Both uncoated and Cu-coated polyester fabrics were characterized by the scanning electron microscope (SEM), energy dispersive spectroscopy (EDX), X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscope (XPS). Relatively uniform and continuous plating was obtained under the given plating conditions. The possible mechanism of electroless copper plating of polyester fabrics utilizing an AgNO₃ activator was suggested. The electromagnetic interference (EMI) shielding effectiveness (SE) was also evaluated to study the shielding behavior of copper-plated polyester fabrics. The results demonstrated that copper-plated polyester fabrics can be applied for EMI shielding.     

TiO<Subscript>2</Subscript> hybrid polypropylene/nickel coated glass fiber conductive composites for highly efficient electromagnetic interference shielding

A highly efficient electromagnetic interference shielding composite based on nickel coated glass fibers (NCGFs) and titanium dioxide (TiO₂) filled polypropylene (PP) is fabricated via the simple melt blending method. Superior shielding effectiveness of 44.5 dB can be achieved with only 1.12 vol% Ni and 0.8 vol% TiO₂ loadings owning to the well-formed conductive network and interfacial polarization effect of TiO₂. The conductive Ni layer coating on the surface of glass fibers constructs an efficient conductive network due to its interfacial distribution between GF and PP. This interconnected Ni network provides fast electron transport channels to absorb the electromagnetic waves. Meanwhile, TiO₂ dispersed among the network of NCGFs induces more interfacial polarization, and thus produces a synergistic effect to enhance the shielding effectiveness of composite. Such composite would be considered as a promising electromagnetic shielding material in aerospace and electronics.     

化学镀镍碳纤维/环氧树脂复合材料电磁屏蔽性能

采用化学镀方法对碳纤维进行表面镀镍, 采用SEM、 EDX、 XRD分析了镀镍碳纤维的微观形貌、 镀层成分和镀层结构, 通过电阻测试研究了镀镍碳纤维的导电性。将体积分数为2.5%、 5%、 7.5%、 10%的镀镍碳纤维作为导电填料制备镀镍碳纤维/环氧树脂复合材料, 并用屏蔽室法测试了不同频段复合材料的屏蔽效能。结果表明: 碳纤维化学镀镍后, 表面形成了一层均匀的复合镀层, 镀层中镍的质量分数高达94%, 镀镍碳纤维的电阻值仅为碳纤维原丝的1/54。镀镍碳纤维/环氧树脂复合材料的电磁屏蔽能力较碳纤维原丝有所提高。复合材料的屏蔽效能随镀镍碳纤维添加量的增加而升高。在低频频段(kHz频段), 复合材料的屏蔽能力主要决定于材料的本征参数, 不同镀镍碳纤维含量的镀镍碳纤维/环氧树脂复合材料的屏蔽能力相差不大; 在中高频频段(MHz、 GHz频段), 镀镍碳纤维/环氧树脂复合材料屏蔽效能主要决定于材料的电阻率。     

导电涤纶织物的制备及其性能研究

采用化学镀的方法制备镀铜和镍导电涤纶织物.分别用四探针法和双轴传输线法测量了导电涤纶织物的表面电阻和电磁屏蔽效能.采用扫描电镜(SEM)分析了不同的粗化时间对织物表面粗糙度的影响和化镀铜和镍过程中的表面形态变化.采用自主设计的"透明胶带法"测量金属与织物纤维的结合力.采用条样法测定织物镀金属前后的断裂强力和断裂延伸率.     

Adsorption characteristic of copper ions and its application in electroless nickel plating on a hydrogel-functionalized poly(vinyl chloride) plastic

A facile and palladium-free process for the electroless plating on poly(vinyl chloride) (PVC) plastic has been demonstrated. The process is based on the Cu adsorption capacity of semi-interpenetrating polymer network (semi-IPN) hydrogel chemically bonded to PVC surface via a simple and one-step approach that applying a chitosan/polyethylene glycol/glutaraldehyde system under mild stirring at room temperature. Therefore, electroless plating can be achieved in the following three steps, namely: (1) the functionalization of PVC by the semi-IPN hydrogel film (2) the adsorption and formation of the catalyst Cu⁰ on the PVC surface, and (3) the electroless nickel plating in plating bath. Batch adsorption experiments are conducted to determine the effects of pH, initial Cu²⁺ ions concentration and the dosage of crosslinking agent glutaraldehyde on copper adsorption and the surface resistance of the corresponding plated-PVC. The activated reaction progress and resulting nickel–phosphorus (Ni–P) layer were characterized by attenuated total reflection Fourier transform infrared, scanning electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The results show that the Cu nanoparticles chemisorbed on the functionalized PVC substrate, could effectively initial the subsequent electroless nickel plating; and a compact and continuous Ni–P layer with amorphous phase was successfully deposited on PVC by this process. Besides, the surface resistance of the plated-PVC as low as 0.5 Ω sq^?1 showed an excellent adhesion with the PVC substrate proved by Scotch-tape test.     

High electrical conductivity and high corrosion resistance fibers with high modulus and high strength prepared by electroless plating of gold on the surface of poly (<Emphasis Type="Italic">p</Emphasis>-phenylene benzobisoxazole) (PBO)

In an attempt to produce glittering gold fibers with high modulus and high strength, gold plating on the surface of poly(p-phenylene benzobisoxazole) (PBO) fibers was carried out by using an electroless plating method. Due to the difficulty in plating gold directly on organic and inorganic fibers, gold plating was carried out on the surface of copper-plated and nickel-plated fibers; for the latter the nickel was plated on the copper-plated fibers. Namely, composite fibers, termed PBO/Cu/Au and PBO/Cu/Ni/Au, were prepared. The morphology of plated fibers was studied by X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy and electrochemical polarization measurements. It was found that gold was uniformly plated on the PBO fiber, and the gold-plated fibers have good corrosion resistance. The electrical conductivities of the two kinds of gold-plated fibers were higher than 4 × 10⁴ S/cm, and their tensile strengths and Young’s moduli were greater than 1.9 GPa and 130 GPa, respectively, when estimated in terms of a single composite fiber.     

Fabrication of conductive copper-coated glass fibers through electroless plating process

A simple electroless copper plating process was employed to prepare copper-coated glass fibers with excellent conductivity. The glass fibers were pretreated by etching, sensitizing, and activating procedures. Disodium ethylenediamine tetra acetate (EDTA-2Na) and hydrazine hydrate (N₂H₄·H₂O) were employed as complex reagent and reductant, respectively. It was found that the copper deposition was greatly influenced by dosage of EDTA-2Na, concentration of sodium hydroxide (NaOH), temperature, and volume of N₂H₄·H₂O. The optimal temperature for electroless copper plating ranged from 40 to 60 °C. The composites were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques. The result showed that the minimum volume resistivity of 0.0010 Ω cm was obtained for the sample with perfect copper coatings on the surface of glass fibers. This method is simple, low-cost, and large production, and can be extended to fabricate other metal-coated glass fibers with distinct conductivity.     

Facile electroless copper plating on diamond particles without conventional sensitization and activation

Conventional electroless plating of copper on diamond particles needs SnCl₂ sensitization and PdCl₂ activation pretreatments, which needs noble metal and consumes a large amount of reducing agent. In this paper, metallic tungsten coatings were first plated onto diamond particles by microwave-heating salt-bath plating (MHSBP) method, and then copper layer was directly plated onto the out surface of the tungsten layer by an electroless plating method with no need of SnCl₂ sensitization and PdCl₂ activation pretreatments. Composition and morphology of the coatings was analyzed by XRD, SEM, and EDS. The results show that the copper coating on the diamond surfaces can be adjusted by control the concentration of CuSO₄·5H₂O and plating temperature, and a full copper coating is achieved with content of CuSO₄·5H₂O of 19.6 g/L in the plating solution at 60 °C. The bending strength of the coated diamond/Cu composites is as high as 630 MPa, which increases 93.3% than the uncoated composites. This work presents an electroless plating of copper can directly on the surfaces of diamond particles with no need of conventional sensitization and activation, and a strong interface combination between coated diamond and copper.     

新型电磁屏蔽材料锡/铜导电布的研制

通过在织物上进行化学镀铜、电镀锡,得到了一种锡/铜柔性电磁屏蔽材料,对制备工艺进行了初步的研究与探讨。并对制得的电磁屏蔽织物进行了电磁屏蔽效能测试和织物的耐摩擦磨损性能测试。试验表明,在电流密度20~35A/cm2、电镀时间600s、电镀温度25~35℃时,得到的锡/铜柔性电磁屏蔽材料具有良好的导电性和电磁屏蔽效能。该织物布面比较柔软,且锡无毒,能克服目前常见镀镍织物对人造成的致敏、毒害等副作用,在民用电磁辐射防护服装市场上有广阔的应用前景。     

Preparation and Research of Electroless Copper on Carbon Fibers

In this paper, Cu coated carbon fibers were prepared using the electroless plating method. Effects of pretreatment, dispersing capability, formaldehyde, temperature, and pH on electroless plating process were studied. The connection between the Cu²⁺ concentration in the electroless plating solution and the plating time at different temperatures was studied. The process of the electroless Cu plating was analyzed and calculated, which derived the activation energy of the electroless copper plating on carbon fibers: Ea = 32.68 kJ/mol. The effect of the mass of carbon fibers and Cu coated carbon fibers which were dispersed in 80 mL distilled water on the conductivity of the solution was also studied. And as a result, the conductivity of the solution increased with the amount increasing. However, when the amount of the fibers was more than 0.08 g, the fibers would be incompletely dispersed. Thus, it could be concluded that the best accession amount of carbon fibers in 80 mL distilled water was 0.08 g. The corresponding conductivity values of carbon fibers and copper-coated fibers were 12.5 and 20.5 µs/cm, respectively.     

Fabrication and characterization of NiTi shape memory alloy synthesized by Ni electroless plating of titanium powder

In this work NiTi shape memory alloy was fabricated from mixed elemental powders, Ni plated titanium powder and Ni heated/plated titanium powder by Ar-sintering. Electroless plating process was utilized to fabricate Ni plated titanium powder. For this purpose titanium powder was plated in an electroless Ni bath for 225?min and hydrazine hydrate was used as a reductant to deposit pure nickel on the titanium particles. Ni plated titanium powder was heat treated under an argon atmosphere at 1000?°C to prepare Ni heated/plated titanium powder. Finally, the three sample powders were pressed by CIP followed by sintering at 980?°C for 8?h to manufacture NiTi shape memory alloy. The prepared powders, as well as sintered samples, were characterized by scanning electronic microscopy (SEM), energy dispersive spectrometer analysis (EDS), X-ray fluorescence (XRF), X-ray diffraction (XRD) and differential scanning calorimetric (DSC). The results indicated the presence of NiTi phase and also non-transformable phases (NiTi₂ and Ni₃Ti) in the heated/plated Ti powder and sintered samples. NiTi compound was dominated phase in the heated/plated sintered sample. All three sintered samples, as well as heated/plated powder, showed one-step phase transformation (B2???B19′).     

Preparation and Performance of Electroless Nickel on AZ91D Magnesium Alloy

The corrosion of magnesium alloy in different plating solutions was researched. The results demonstrated that corrosive condition of the alloy immersed in nickel chloride solution and nickel sulfate solution is serious and in nickel acetate solution and nickel nitrate solution is less. Magnesium alloy was handled with four acid pickling formulas and two activation formulas and the effects of different pickling formulas and activation formulas were researched through comparative experiment. The experimental results indicated that after handed with pickling formula about 500 mL L^?1 H₃PO₄ (85%), 110 mL L^?1 HNO₃ (68%), room temperature for 30 s and activation formula about 375 mL L^?1 HF (40%), room temperature for 10 min, magnesium alloy could realize electroless nickel plating directly and the performance of the prepared plating was much better. The properties of the nickel-plating coating were researched by electrochemical workstation, scanning electron microscope, and X-ray diffraction. The results demonstrated that this Ni–P coating was very uniform and meticulous; the structure of Ni–P coating was amorphous; and comparing with magnesium alloy, the corrosion potential of this plating increased about 799 V and the corrosion current density declined obviously. The nickel-plating coating effectively improved the anticorrosion performance of magnesium alloy.     

Silver-coated glass fibers prepared by a simple electroless plating technique

Silver-coated glass fibers have been successfully fabricated using a simple electroless silver plating. The structures of the silver/glass fiber composites were characterized by X-ray diffraction, high-resolution transmission electron microscopy, and scanning electron microscopy, respectively. The morphology investigation showed that the silver coatings were compact and continuous. The minimum volume resistivity could reach 4.53 × 10^?4 Ω cm, suggesting excellent electric conductivity. It was found that the quality of silver deposition was influenced by dosage of ammonia solution and plating temperature. Ammonia solution served as complexing reagent and supplied an alkaline media, and higher temperature easily led to metallic oxidation. The current method is simple-handle, inexpensive, large production, and the obtained silver/glass fibers can be used as fillers to fabricate electromagnetic wave shielding materials.     

Preparation of multi-functional fabric via silver/reduced graphene oxide coating with poly(diallyldimethylammonium chloride) modification

In order to obtain multi-functional textile, polyester (PET) fabric was modified with poly(diallyldimethylammonium chloride) (PDDA) followed by silver/reduced graphene oxide (Ag/RGO) coating through chemical reduction method. The Ag/RGO coated PET fabrics were systematically characterized by X-ray photoelectron spectroscopy, scanning electron microscope and X-ray diffraction. The deposit weight, electrical resistance, static voltage half-life period, heat generation and water contact angle tests of the fabrics with and without PDDA modification were evaluated. It is concluded that there are uniform and dense silver particles and reduced graphene oxide (RGO) sheets deposit on the surface of the PET fabric modified with PDDA. Compared with the coated fabric without PDDA modification, the Ag/RGO coated PET fabric modified with PDDA shows lower electrical resistance of 0.173 Ω/sq, excellent antistatic property with half-life period of 0.5 s, heat generation with temperature keeping to 69.6 °C at voltage of 4 V and hydrophobicity with a water contact angle of 140.1°. Furthermore, the PDDA modification improves adhesion between Ag/RGO coating and PET substrate. In addition, electromagnetic interference (EMI) shielding effectiveness (SE), absorption and reflection characteristics were determined by a vector network analyzer in 1 GHz–18 GHz X-band range. The results exhibit that Ag/RGO coated PET fabric possesses an excellent EMI SE ranging from 52 to 57 dB and could be used as lightweight and flexible electromagnetic absorption materials.     

镍-铜复合镀层Kevlar纤维的研制

采用化学镀技术制备了镍-铜复合镀层的导电Kevlar纤维。进行了自制金属化试剂对Kevlar纤维的粗化处理,研究了镍镀层含量、添加剂聚乙二醇(PEG6000)和亚铁氰化钾(K4Fe(CN)6))对化学镀铜的影响。实验表明,镍镀层质量增加率为10%较适宜继续化学镀铜;添加剂均可降低化学镀铜的沉积速度,PEG6000能够细化圆滑镀层颗粒,K4Fe(CN)6使得镀层表面平整光亮,制得光滑致密有金属光泽的铜镀层,并提高其导电性。镍-铜复合镀层Kevlar纤维的断裂强力为45 N,表面电阻为0.4Ω/cm。     

Investigation on a Non-cyanide Plating Process of Ni-P Coating on Magnesium Alloy AZ91D

In this research we presented a non-cyanide plating process of Ni-P alloy coating on Mg alloy AZ91D. By applying a new process flow of electroless nickel plating in which zinc coating is used as transition of Ni-P coating on Mg alloy AZ91D, the process of copper transition coating plated in the cyanides bath can be replaced. A new bath composed of NiSO4 was established by orthogonal test. The results show that zinc transition coating can increase the adhesion and pH 4.0 and 95℃, respectively. The present process flow is composed of ultrasonic cleaning→alkaline cleaning→acid pickling→activation→double immersing zinc→electroplating zinc→electroless nickel plating→passivation treatment.The present non-cyanide process of electroless nickel plating is harmless to our surroundings and Ni-P coating on Mg alloy AZ91D produced by present process possesses good adhesion and corrosion resistance.     

Synthesis and characterization of functionally graded nickel‐nickel coated ZrO2 composite coating

Electroless‐nickel plated ZrO₂ (NCZ) particles have been used to produce a functionally graded nickel‐electroless‐nickel plated ZrO₂ composite coating. So, electroless‐nickel plated ZrO₂ particles concentration was continuously increased from 0 to an optimum value in the electroplating bath (Watt's bath). The substrate was ST37 steel and the thickness of the coating was approximately 50 μm. Also a uniformly distributed nickel‐electroless‐nickel plated ZrO₂ composite coating has been manufactured as comparison. The composite coatings were characterized by scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. Structure and phase composition were identified by X‐ray diffraction analysis. Microhardness of the coatings was evaluated by employing a Vickers instrument. Three‐point bend test was carried out to compare the adhesion strength of the coatings. Dry sliding wear tests were performed using a pin‐on‐disk wear apparatus. The electrochemical behavior of the coatings was studied by electrochemical impedance spectroscopy. The microhardness measurements showed that, with increasing the co‐electrodeposited electroless‐nickel plated ZrO₂ particle content in the nickel matrix, the microhardness increases from interface towards the surface of the functionally graded composite coating. Bend, wear and electrochemical test results confirmed that the functionally graded composite coating has higher adhesion, wear resistance and corrosion resistance as compared with the uniformly distributed coating. This has been attributed to lower mechanical mismatch between coating and substrate in functionally graded composite coating with respect to the uniformly distributed one.     

Effective electromagnetic interference shielding by electrospun carbon fibers involving Fe2O3/BaTiO3/MWCNT additives

Carbon fibers were prepared as an electromagnetic interference shielding material by electrospinning and heat treatment methods. To increase the electromagnetic shielding effectiveness, additives (Fe₂O₃/BaTiO₃/multi-walled carbon nanotubes) were included due to their excellent dielectric and coercive force properties. The additives were observed to cluster on the surface of fibers; additive metal oxides did not show any structural changes during the heat treatment, retaining their original magnetic properties. The permittivity of the materials improved significantly as a result of the added carbon nanotubes and their high electrical conductivity. Magnetic properties such as saturated magnetization and coercive force were also improved by the presence of Fe₂O₃/BaTiO₃, which enhanced the permeability. The improved permittivity and permeability significantly contributed to effective shielding of electromagnetic interference measured at 37 dB.     

Metallization of Kevlar fibers with gold

Electrochemical gold plating processes were examined for the metallization of Kevlar yarn. Conventional Sn(2+)/Pd(2+) surface activation coupled with electroless Ni deposition rendered the fibers conductive enough to serve as cathodes for electrochemical plating. The resulting coatings were quantified gravimetrically and characterized via adhesion tests together with XRD, SEM, TEM; the coatings effect on fiber strength was also probed. XRD data showed that metallic Pd formed during surface activation whereas amorphous phases and trace amounts of pure Ni metal were plated via the electroless process. Electrodeposition in a thiosulfate bath was the most efficient Au coating process as compared with the analogous electroless procedure, and with electroplating using a commercial cyanide method. Strongly adhering coatings resulted upon metallization with three consecutive electrodepositions, which produced conductive fibers able to sustain power outputs in the range of 1 W. On the other hand, metallization affected the tensile strength of the fiber and defects present in the metal deposits make questionable the effectiveness of the coatings as protective barriers.