Surface characteristics of electroless nickel plated electromagnetic shielding wood veneer

Wood is a kind of porous natural material with very poor electro-conductivity, and it has almost no function of electromagnetic shielding. The method of electroless nickel plating was used to produce wooden material with electrical and effective electromagnetic shielding properties. Ni-P alloy layer was obtained on wood surface. The surface feature of plated wood veneer was observed by SEM and the surface composition and microstructure of the layer under different conditions were investigated by EDS and XRD respectively. Meanwhile, the relevant surface resistivity and electromagnetic shielding effectiveness were measured. Correlations of the phosphorous content in the layer to the structure of Ni-P alloy, electro-conductivity and electromagnetic shielding of plated veneers were discussed. SEM photos showed that the surface of electroless nickel plated veneers were covered with Ni-P alloy layer entirely, which made wood veneers more like metal. At the same time, the results showed that with the decreasing of the phosphorous content in the layer, the microstructure of Ni-P alloy layer transformed to be microcrystalline and electro-conductivity and electromagnetic shielding effectiveness were improved. When the phosphorous content was less than 2.37wt pct in the layer, the microstructure of Ni-P alloy layer was microcrystalline structure and its sur- face resistivity and electromagnetic shielding effectiveness were nearly 0.5Ω/□ and 55-60dB respectively.

Characterization and Properties of Electroless Nickel Plated Poly (ethylene terephthalate) Nonwoven Fabric Enhanced by Dielectric Barrier Discharge Plasma Pretreatment

In order to develop a more economical pretreatment method for electroless nickel plating, a dielectric barrier discharge （DBD） plasma at atmospheric pressure was used to improve the hydrophilicity and adhesion of poly （ethylene terephthalate） （PET） nonwoven fabric. The properties of the PET nonwoven fabric including its liquid absorptive capacity （WA）, aging behavior, surface chemical composition, morphology of the surface, adhesion strength, surface electrical resistivity and electromagnetic interference （EMI）- shielding effectiveness （SE） were studied. The liquid absorptive capacity （WA） increased due to the incorporation of oxygen-containing and nitrogen-containing functional groups on the surface of PET nonwoven fabric after DBD airplasma treatment. The surface morphology of the nonwoven fibers became rougher after plasma treatment. Therefore, the surface was more prone to absorb tin sensitizer and palladium catalyst to form an active layer for the deposition of electroless nickel. SEM and X-ray diffraction （XRD） measurements indicated that a uniform coating of nickel was formed on the PET nonwoven fabric. The average EMI-SE of Ni-plating of PET nonwoven fabric maintained a relatively stable value （38.2 dB to 37.3 dB） in a frequency range of 50 MHz to 1500 MHz. It is concluded that DBD is feasible for pretreatment of nonwoven fabric for electroless nickel plating to prepare functional material with good EMI-SE properties.

Research on 3D Braided Nickel Plated Carbon Fiber/epoxy Resin Composites and Their Electromagnetic Protection Properties

To develop electromagnetic protection composites with integrated structure -function properties, the three-dimension (3D) braided nickel plated carbon fiber/epoxy resin (Ni-CF3D/EP) composites were prepared based on 3D five-directional braiding, unitary nickel plating and mold compression shaping. The electromagnetic protection properties of Ni-CF3D/EP composites including shielding effective- ness (SE) and reflection loss against plane electromagnetic wave, shielding properties against electromagnetic pulse (EMP) were investigated. The test results show that the novel composites have good electromagnetic protection properties in a wide frequency range of 14 kHz～18 GHz with SE of 42 dB～95 dB, the absorption bandwidth of –5 dB in 2 GHz～18 GHz can reach 10 GHz and the pulse peak SE against EMP is 43.7 dB which can reduce the electromagnetic energy greatly. Meanwhile, the mechanic properties were also investi- gated and the results indicate that the Ni-CF3D/EP composites can replace metal materials for loading-bearing structural applications because of their excellent mechanic properties.

Electroless nickel plated graphite fibers and surface behavior in G_(r(Ni))/6061Al composite

The electroless nickel plated graphite fibers reinforced aluminum matrix composites (Gr(Ni))/Al) were produced by squeeze casting, and the microstructure of Gr(Ni)/Al composite and surface behavior of Ni-P coating were studied. The optimum process of electroless Ni-P plating included: burning to get rid of glue→degreasing→neutralization→acidulating→sensitizing→activation→electroless plating. The surface analysis results show that the electroless nickel plating can diffuse into the graphite fiber surface during the squeeze casting, and the Ni-P coating and aluminum alloys can produce brittle phase NiAl3 or NiAl. The X-ray diffraction(XRD) results indicate that Al4C3 is so little that no Al4C3 peaks are found, and the harmful Al4C3 can be decreased by the electroless plating Ni-P coating. The coating improves the interfacial bonding of continuous graphite fibers reinforced aluminum matrix composites.

Formation mechanism of electroless plating nickel-based composite coating on highly active rare earth magnesium alloys and its corrosion resistance and adhesion performance

The process of preparing anodic oxide film containing active sites and electroless nickel plating on highly active rare earth magnesium alloy was developed.The formation mechanism of electroless nickel plating on active anodic oxide film and the structure and properties of the composite coating were studied by several surface and electrochemical techniques.The results showed that Ag nanograins with an average size of 10 nm were embedded into the anodic oxide film with pores of 0.1−2μm.Ag nanoparticles provided a catalytic site for the deposition of Ni-B alloy,and the Ni crystal nucleus was first grown in horizontal mode and then in cylindrical mode.The corrosion potential of the composite coating increased by 1.37 V and the corrosion current reduced two orders of magnitude due to the subsequent deposition of Ni-P alloy.The high corrosion resistance was attributed to the misaligning of these micro defects in the three different layers and the amorphous structure of the Ni-P alloy in the outer layer.These findings provide a new idea for electroless nickel plating on anodic oxide film.

冲击镀镍在氨基磺酸盐镀镍中作为底层的应用

文章针对铁件表面氨基磺酸盐镀镍层耐蚀性差的问题,使用冲击镀镍作为氨基磺酸盐镀镍的底层,研究了冲击镀镍作为氨基磺酸盐镀镍底层对氨基磺酸盐镀镍的影响。通过X射线测厚仪控制镀层厚度大致相同,使用扫描电镜、显微硬度计、贴滤纸方法等对镀层进行测试分析。结果表明,在冲击镀镍后再进行氨基磺酸盐镀镍可以降低镀层的孔隙率,镀层硬度变化不是很大,焊接性能有了一定的提高。

Electroless Nickel Plating and Electroplating on FBG Temperature Sensor

Metal-coated fiber Bragg grating（FBG）temperature sensors were prepared via electroless nickel（EN）plating and tin electroplating methods on the surface of normal bare FBG.The surface morphologies of the metal-coated layers were observed under a metallographic microscope.The effects of pretreatment sequence,pH value of EN plating solution and current density of electroplating on the performance of the metal-coated layers were analyzed.Meanwhile, the Bragg wavelength shift induced by temperature was monitored by an optical spectrum analyzer.Sensitivity of the metal-coated FBG（MFBG）sensor was almost two times that of normal bare FBG sensor.The measuring temperature of the MFBG sensor could be up to 280℃,which was much better than that of conventional FBG sensor.

Properties of fluoride film and its effect on electroless nickel deposition on magnesium alloys

The physical characteristics and microstructure of the fluoride film formed during activation were investigated using SEM,XPS and SAM,and its stability in electroless nickel(EN) bath was analyzed.The effects of the fluoride film on EN deposition were studied additionally.The results show that the fluoride film on magnesium alloys is a kind of porous film composed of MgF2 with thickness of 1.6-3.2 μm.The composition of the activation bath and pretreatment of EN processing have influence on the composition of the fluoride film.The fluoride is stable and dissolves little in EN bath;as a result,the fluoride film can protect magnesium substrate from the corrosion of EN bath.The composition of fluoride determines the initial deposition of EN and part of the fluoride film finally exists as inclusion in EN coating.

Electroless nickel plating on the surface of carbon fibers

The electroless nickel plating on the surface of carbon fibers was prepared by pretreating the carbon fibers in order to increase their conductivity,and consequently enhance the EMI shielding effectiveness of the composites.The relationship between the performance of depositing coat and pH value,temperature,reaction time and the way of agitation was studied.Results show that the depositing quality is stable under pH between 4.5 and 5.0,temperature between 75 ℃ and 85 ℃,reaction time for 10 min and air agitation.The uniform and compact nickel layer deposited on carbon fibers was proved by XRD and SEM,and the electrical resistivity of carbon fibers with nickel coating was tested.Results indicate that the electrical resistivity of carbon fibers with electroless nickel plating is decreased by an order of magnitude compared with that of carbon fibers.It means that nickel coating can greatly improve the electromagnetic interference shielding properties of carbon fibers.

Nickel Electroplating

Nickel electroplating has been used practically for decades, is easy to plate, but there is an unknown interest in it. Nickel electroplating as a basis of surface treatment is shown practically from basics to the applied electronics use. At first the basics of nickel electroplating, for example, purpose, use, merit & demerit, nickel plating solution, current efficiency, limiting current density, additional agents and their behaviors are surveyed. And the points of nickel deposition already practically used such as decorative nickel plating, satin nickel plating and functional nickel plating, which has very high throwing power and has been used for electronics, are described in detail.

Electroless nickel fabrication on surface modified magnesium substrates

In recent years,magnesium(Mg)has evolved as a salient material,in affiliation with electroless nickel(Ni)coating,which have found applications in automobiles,aerospace and confederate fields attributing to its excellent inherent weight sensitive properties.However,being acknowledged for its remarkable auxiliary properties like flexible machining,appreciable weight sensitivity and ability to be patently diecast into mesh constructs,magnesium is prejudiced by aeronautical standards predominantly for its inferior corrosion resistance properties.In this sense,electroless nickel plating on magnesium and its alloys has been suggested to extricate it from corrosion problem and make it more competitive in industrial and defence applications.Autocatalytic fixation of metal ions onto respective substrates accrues and alters their mechanical,electrochemical and tribological properties,destitute of any electric current aid.This proficiently identified technique is prosecuted with the assistance of a series of sequenced operations involving a prior pretreatment,which corresponds to the chemical cleaning of the substrate surface;electroless coating;and a later activation process which is a mild etching of the electroless coated surface.The susceptibility of magnesium to this methodology has advanced and propagated its exercise and applicability in aircraft,satellites and allied aeronautical fields.Contemporarily,researchers have proposed various eco-friendly and modified duplex and composite coatings which have transmuted properties of these appendages by tailoring alloy compositions and reagents employed.This review article systematically colligates various considerations and evaluations on electroless nickel applications of magnesium and its alloys and explicates how it anchors its practice in the respective domains.Furthermore,a comprehensive analysis is devised based on the pre-existing treatment methods for accomplishing the same.

Nickel and nickel-phosphorous matrix composite electrocoatings

Nickel and nickel-phosphorous matrix composite coatings reinforced by TiO2,SiC and WC particles were produced under direct and pulse current conditions from an additive-free Watts' type bath.The influence of the variable electrolysis parameters(type of current,frequency of current pulses and current density) and the reinforcing particles properties(type,size and concentration in the bath) on the surface morphology and the structure of the deposits was examined.It is demonstrated that the embedding of ceramic particles modifies in various ways the nickel electrocrystallisation process.On the other hand,Ni-P amorphous matrix is not affected by the occlusion of the particles.Overall,the imposition of pulse current conditions leads to composite coatings with increased embedded percentage and more homogenous distribution of particles in the matrix than coatings produced under direct current regime.

Removal of nickel from spent electroless nickel-plating bath with nickel foam cathode

The electrochemical method was used to remove nickel ion from spent electroless nickel plating bath (pH=5 3). An electrolytic cell was composed of a porous nickel foam cathode and an inert RuO 2/Ti anode. Nickel ions were reduced and deposited on the surface of the nickel foam cathode. The effect of current density (i), linear velocity of wastewater(v), gap between cathode and anode(d C/A) and reaction time(t) on nickel removal rate and current efficiency were studied. As reaction time prolonged, nickel removal rate increased while current efficiency decreased. And larger v and smaller d C/A can enhance nickel removal rate and increase current efficiency by promoting mass transfer and dropping concentration polarization. The effect of current density on nickel removal by electrochemistry was related to other parameters. After three hours’ electrolysis with i=1 0 A/dm2, v=18 5 cm/min and d C/A=0 5 cm, nickel removal rate and current efficiency reached 85 6% and 29 1%, respectively.

THE STUDY OF ELECTROLESS NICKEL ACCELERATING AGENT

The effects of accelerating agent on the deposition speed of Electroless Nickel Plating, the stability of solution and the corrosion resistant of The EN coatings were studied. The influence of A1 content on EN activation energy, the rest potential and polarization cures are measured. The mechanism of the acceleration effect of A1 on the EN plating was proposed.

Effect of electroless plating nickel treatment on electrode properties of Zr-based AB_2 type alloy

An electroless plating nickel treatment was processed to improve the active behaviors and discharge capacities of Zr based AB 2 alloys. The effects of the nickel coating on the surface appearance, the structure of the alloy powders and the electrode characteristics were investigated. It is found that the Ni rich layer formed through electroless plating nickel treatment plays an important role on the initial activation property and the discharge capacity of Zr based alloy. The optimal content of electroless plating nickel is about 15%, and the discharge capacity of the electrode can be increased to 400?mA·h·g -1 after 6 cycles. Although coated nickel is beneficial for quick activation and discharge capacity, excessive electroless plating nickel can result in a decreased discharge capacity.

Comparison Between Electrolysis and Reduction for Treatment of Spent Electroless Nickel Plating Bath

There are lots of residual nickel and organic compounds in the spent electroless nickel plating bath. It not only wastes resource but also causes environmental pollution if the wastewater is discharged without treatment. In this paper, electrolytic method and reduction method for treating spent electroless nickel plating bath were compared. The factors studied included reaction time, pH, temperature, effectiveness and cost. It was found that the recovery rate of nickel by reduction was 99.9% under the condition ofpH 6, 50℃ for 10 min. The purity of reclaimed nickel was 66.1%. This treatment needed about 16 g NaBH4 for a liter spent solution, which cost RMB 64 Yuan. For electrolysis method, with pH 7.6, 80℃, 0.45 A （current intensity） for 2 h, the recovery rate reached 97.3%. The purity was 88.5% for the reclaimed nickel. Moreover, it was found that through electrolysis, the value of TOC （Total Organic Carbon） decreased from 114 to 3.08 g·L^-1 with removal rate of 97.3%. The main cost of electrolysis came from electric energy. It cost about 0.09 kWh （less than RMB 0.1 Yuan） per liter wastewater. Compared with reduction, electrolysis had more advantages, so the priority of selection should be given to the electrolysis method for the treatment of spent electroless nickel plating bath.

Purification and Regeneration of Spent Electroless NickelPlating Baths by Electrodialysis

A method using electrodialysis to seperate phosphite from spent electroless nickel (EN) plating solution was studied. The major working parameters for the electrodialyzer with our selected membranes such as voltage, current and the flow rate of spent EN bath and condensed solution were optimized. Under the optimum operating conditions, spent EN bath could be effectively purified. And then the purified solution was replenished and reused for EN plating. The life of the EN bath was prolonged for more than 17 metal turnovers (M.T.Os). It showed that the electrodialysis method was one of the most effective means for purification and regeneration of spent EN plating baths and for saving resources and reducing waste.

STUDY ON THE SURFACE OF TITANIUM CARBIDE PARTICLE PACKAGED NICKEL

Two kinds of packaged processes by nickel on the surface of titanium carbide particle are studied in this work. One is the chemical nickel-plating, the other is the organometallic compound decomposition. The composition, structure and morphology of the packaged powder were analyzed with XRD, DAT/TGA, SEM, EPMA etc. It has been shown that nickel was even dispersed on the surface of titanium carbide particle by the. two kinds of processes, deposited nickel exists as spherical particles of about 0.1 μm in diameter. The merits and demerits of the two kinds of processes have been compared, the organometallic copmound decomposition among them is a kind of hopeful method, which is not used by other researchers.

Electroplating zinc transition layer for electroless nickel plating on AM60 magnesium alloys

Electroplating zinc coating as transition layer of electroless nickel plating on AM60 magnesium alloys was investigated. The zinc film can be deposited in a pyrophosphate bath at 50-60℃under current density of 0.5-1.5 A/dm2. A new fore treatment technology was applied by acid cleaning with a solution containing molybdate and phosphorous acid, by alkaline cleaning in a bath containing molybdate and sodium hydroxide. The subsequent electroless plating was carried out in nickel sulfate bath. The SEM observation shows that the deposition is uniform and compact. The polarization curve measurements show that the corrosion potential of the zinc plating in 3.5% NaCl is about -1.3 V(vs SCE) which is noble than that of magnesium substrate. The zinc electroplating can be applied as the pretreatment process for electroless nickel plating on magnesium alloys.

Electroless nickel-plating on die cast magnesium alloy AZ91D

Electroless nickel-plating on die cast magnesium alloy AZ91D was investigated. Growth of the electroless nickel-plating coating was characterized using scanning electron microscopy. Corrosion resistance of the coating was evaluated by open circuit potential and potentiodynamic polarization curves in 3.5%(mass fraction) NaCl solution. The results show that plating deposition is initiated on the crevices and then spread onto primary α phase. The corrosion potentials for die cast magnesium alloy AZ91D and nickel-plating coating are about -1.45 V and -0.36 V(vs. SCE),respectively. No discoloration,cracks,blisters,or peeling appear by heat-quench test. The results show that the corrosion potential of Ni-P coating is increased by 1 000 mV and corrosion resistance for die cast magnesium alloy AZ91D is improved. The adhesion between the coating and the substrate is excellent. Electroless nickel plating is a promising method to enhance magnesium alloys resistance for attacking.