Optimum Bath Research Articles

Friction and wear behaviour of BN(h) and Ag incorporated nickel phosphorous coatings under dry reciprocating sliding conditions

ABSTRACT Ni–P–BN(h)–Ag hybrid composite coatings were fabricated on the steel substrate by a scalable electroless deposition process. The optimum bath composition and operating conditions were selected to obtain defect-free composite coatings with ∼50 μm thickness. Further, to enhance the hardness, as-deposited coatings were subjected to heat treatment in a tubular furnace at 400°C for 1 h. The dry sliding wear behaviour of the as-deposited (AD) and heat-treated (HT400) composite coatings was evaluated using a linear reciprocating tribometer. The average friction coefficient of the hybrid coating was ∼0.14 (in as-deposited condition) and ∼0.16 (in heat-treated condition); these values represent 51.72% and 52.94% reduction over non-hybrid Ni-P coatings. The specific wear rate of the as-deposited and heattreated composite coatings was found to be 50% and 43% lower, respectively, than that of conventional Ni–P coatings. Detailed wear track analysis was carried out to identify underlying wear mechanisms and tribochemical interactions.

Physical and electrochemical behavior of black nickel coatings in presence of KNO3 and imidazole additives

As a unique type of nickel films, black nickel coatings possess remarkable optical and electrical properties but limited applications owing to their poor structure and corrosion resistance. In this study, black nickel coatings were electrodeposited on St37 steel and optimized utilizing nickel Watts bath modified with potassium nitrate. By investigating the coating structure and current efficiency (CE), optimum bath was determined as 190 g/L NiSO4, 25 g/L NiCl2, 30 g/L H3BO3, and 25 g/L KNO3 which resulted in CE of 79% and a compact structure. Next, cyclic voltammetry and chronoamperometric tests revealed that the dominant deposition mechanism was instantaneous nucleation. Besides studying the changes in CE and cathodic polarization, the improvement of properties with addition of imidazole was investigated by studying the surface morphology, phase structure, light absorption, and corrosion behavior using SEM, XRD, differential reflectance spectroscopy (DRS), potentiodynamic polarization, and electrochemical impedance spectroscopy tests, respectively. Adding imidazole to the deposition bath reduced the grain size and crack width from micro-scale to nano-scale, without affecting its nucleation mechanism or light absorption property. Also, imidazole enhanced the corrosion resistance of the black nickel coatings by 62% reduction of corrosion current density and increasing its polarization resistance by 58%.

Effects of bath composition and thermal treatment on the performance of Co-Ni-Mo-P electrocatalyst supported on carbon for the electro-oxidation of ethanol

We explored the influence of bath compositions on the performance of as-deposited (ASD) Co-Ni-Mo-P electrocatalyst for the electrooxidation of ethanol using single-factor analysis. Further the effects of annealing temperature of the ASD electrocatalysts and influence of phosphorus on the catalyst performance were also evaluated. The specific peak currents for the forward (if) and backward (ib) oxidations and their ratios (if /ib) obtained from cyclic voltammetry (CV) were used to investigate and characterize the electrocatalyst performance. The results from the single-factor experiments showed that both current densities (if and ib) increased with increasing electroless bath concentrations for all the bath species studied. Using if /ib ratio as the response factor, an optimum bath molar ratio of NiSO4 (N): CoSO4 (C): Na2MoO4 (M): NaPH2O2 (P) for the as-deposited catalyst was identified as 13.0:100.0: 1.0: 94.0 which was equivalent to Ni:Co:Mo:P surface composition ratio of 3: 1.5: 1.0: 1.1 (Ni3Co1.5MoP1.1) in the electrocatalyst. The absence of phosphorus in the ASD electrocatalyst resulted in poor ethanol oxidation performance (low if /ib ratio) and low catalyst stability. An optimal temperature of 350 °C was determined for thermally treated ASD electrocatalyst under H2/Ar gas for which if and if /ib ratios were higher than at any other annealing temperature including the ASD electrocatalyst and this was attributed to the formation of a new phase - Co2Mo3. The stability of the thermally treated electrocatalyst was found to be lower than that of ASD electrocatalyst. Overall, the work provided a direction on the use of electroless deposition method to optimize and prepare electrocatalyst containing phosphorus for effective electrooxidation of ethanol.

Influence of additives on morphology, orientation and anti-corrosion property of bright zinc electrodeposit

The use of new combination of additives such as cetyltrimethylammonium bromide (CTAB), benzoic acid (BA) and 2-bromo-3-chloro-5, 5-dimethylcyclohex-2-enone (BCD) develops bright zinc electrodeposit on mild steel. The additives combination has a synergistic effect on improving faradaic efficiency as well as throwing power of optimized bath. The morphology, orientation and anti-corrosion property of zinc electrodeposit has been systematically studied in absence and presence of individual and mixture of additives. The presence of all the three additives such as CTAB, BA and BCD in plating bath form nanocrystalline, bright zinc coating with (100), (110) preferred orientation with smaller surface roughness and superior anticorrosion property. The presence of any two additive mixtures out of three as well as single additive gave deposit with lower corrosion resistance. The influence of brightener BCD concentration on morphology, orientation and anti-corrosion property of bright zinc coating in optimum bath has been examined.

Optimization of electroless bath process parameter for improving the tribology behavior of Ni-P/CaBr2 composite coating against the hardened EN-31 steel

Ceramic, polymers and solid lubricants were used as reinforcements in the electroless Ni–P deposit, which is in-soluble in nature. Impingement of in-soluble particles has improved the hardness and wear resistance of the Ni–P deposit. However, the question still remains on the bonding of matrix and reinforcement particle during the wear at high load conditions. Hence, to strengthen the Ni–P deposit, a soluble reinforcement particle (CaBr2) has been used in this study. A detail study on the role of bath composition (Nickel sulphate and CaBr2) on the mechanical and tribology behavior of alkaline electroless Ni–P/CaBr2 composite coatings is reported. Coatings were carried out with various weight combination of CaBr2 particle (1 g l−1, 2 g l−1, and 3 g l−1) and source of nickel (16 g l−1, 18 g l−1, and 20 g l−1) in the bath. The optimum bath composition to achieve higher hardness, low surface roughness (Ra), low coefficient of friction (COF), and wear rate were analyzed using response surface methodology (RSM). ANOVA was used to identify the influencing factor on the output responses and an empirical model has been formulated. Ni–P/CaBr2 coating exhibited a high surface roughness of 1.505 μm for the weight combination of 1 g l−1 of CaBr2 and 20 g l−1 of nickel sulphate. High surface hardness of 793 HV0.05 and low wear rate of 3.33 × 10−6 gm.m−1 was achieved for the high weight combination of CaBr2 particle and nickel sulphate. The obtained experimental results were closer to the predicted results, confirming the significance of the model for optimizing the bath composition for Ni–P/CaBr2 composite coatings. Various characterization techniques like Scanning Electron Microscope-Electron Dispersive Spectrum (SEM-EDS), x-ray Diffractometer (XRD) and 3D non-contact surface profilometer were used to justify the wear results obtained through the experimentation.

Study on the Electrodeposition of Trivalent Chromium Plating Bath in the Presence of Oxalate Anions

Chromium is not easily electrodeposited from aqueous solutions based on trivalent chromium. Hull cell is employed to determine the optimum bath composition, and several electroplating baths were evaluated. The new bath with oxalate and acetate anions produces very good coatings and our results are valuable for the electroplating community and electrochemists. The baths presented a current efficiency of 37%, high covering power at 8.2 cm, low deposition potential of 7.3 V, and deposition rate of 0.4 μm/min. However, the Hull cell required a high current density (30 A/dm2). After 2 h of the electrodeposition process, the pH values change by 0.2 units. In addition, the baths were analyzed after electrolysis to detect Cr(VI), and this cation was not detected. Our study not only has a technological contribution but also presents a new explanation for the nature of these baths. In the literature, the usual explanation of the performance of these baths is based on the formation of complexes between ligands and Cr(III); however, our novel explanation is based on the high stability of water in the first solvation sphere of Cr(III), and we support our suggestions with several references to chromium solvation studies. The ligand-exchange reaction explanation is replaced by the second sphere hypothesis, that is, our explanation is based on the large stabilization energy of Cr−O bonds in [Cr(H2O)6]3+. Figure 1

Characterisations of low phosphorus electroless Ni and composite electroless Ni-P-SiC coatings on A356 aluminium alloy

ABSTRACTA low phosphorus electroless nickel coating of Ni-2.5 wt-%P alloy and a composite coating of Ni-5 wt-%P-SiC were prepared on A356 aluminium alloy substrates using two types of electroless bath solutions, an alkaline bath for low phosphorus and acidic for composite plating. The coatings morphologies have been characterised using optical and scanning electron microscopy. In addition, X-ray diffraction, microhardness, reciprocating wear testing and adhesion tests have been conducted to characterise structure and mechanical properties of the resulting coatings. The results obtained revealed that a crack-free and homogeneous coating could be produced using an optimum bath formulation. The maximum thickness of the composite coatings was 50 µm, the thickness of coatings tested. The composite coating was more resistant to wear in comparison to the low phosphorus nickel one, but had lower adhesion.

Cellulose Microfibrils as a Pore Former in Electroless Co-Deposited Anodes for Solid Oxide Fuel Cells

A study was conducted to investigate the feasibility of Cellulose Microfibrils (CMF) as a pore former in the manufacture of Solid Oxide Fuel Cell (SOFC) anodes using Electroless Co-Deposition (ECD). Previous work into the use of ECD to produce SOFC anodes has found that the lack of porosity restricted the maximum power density of the cell. Studies have also shown that an anode produced by ECD using rice starch as a pore former nearly doubled the power density of a cell. Therefore by increasing the anode porosity, the cell’s power density should also increase and lead to greater performance of SOFCs for the power generation market. As the choice of pore former is closely related to the size and shape of pores produced, a whisker shaped pore former will produce a more cylindrical pore once removed. These cylindrical pores will increase the chances of producing an interconnected pore network compared with more spherical pores, therefore improving the gas diffusion throughout the anode. Previous work by the author on using cellulose as a pore former has shown that a smaller pore former is able to produce a larger increase in porosity due to a greater inclusion within the coating. Samples were produced using four different cellulose powders as pore formers, ranging from 20μm to 200μm and varying morphologies. The result showed that the smaller cellulose powder had a greater impact on the porosity than the larger sized pore former. The smaller cellulose (20μm) increased the overall porosity by 218% and increased the total pore surface area by 2910%. This increase in porosity and surface area will allow for a greater density of reaction sites within the electrode increasing the overall power density of the cell. However the cellulose which produced the greatest change had a particulate morphology, with the fibrous cellulose being too large to have a significant inclusion within the coating to produce the desired microstructure. Therefore by using a cellulose pore former with similar size but with a cylindrical morphology will allow for a greater chance of producing an interconnected pore network required. Cellulose Microfibrils (CMF) typically has a size of ranging from 10μm to 50μm (average: 30μm) with a fibrous structure. This combined with its unique set of properties, such as being insolubility in water with a hygroscopic character and no melting point, makes it highly suitable for use with the ECD process. Initial tests with CMF showed that a 10g/l bath loading of CMF produced an increase in Porosity by 200%, which was similar to the 20μm particulate cellulose previously used. Therefore button cells were produced using ECD with 10g/l, 5gl, and 2g/l bath loadings of CMF added to act as a pore former for the anode. A range was used to determine the optimum bath loading to produce the required microstructure for a SOFC anode. Standard lanthanum strontium manganite based cathodes were manufactured using the conventional applied using the standard method of screen printing and sintering. A cell was also produced using the same methods but without pore formers, to act as a comparison and determine any improvement produced by the addition of CMF as a pore former. These cells were then characterized using Electrochemical Impedance Spectroscopy and a Scanning Electron Microscope with Energy Dispersive X-Ray Analysis capabilities. These were used to determine the power densities of the cells and the pore structure produced via a cross sectional analysis. A mercury porosimeter was used to determine the pore content and size in the ECD anodes. Figure 1

Dynamic mechanical, thermal and wear analysis of Ni-P coated glass fiber/Al₂O₃ nanowire reinforced vinyl ester composite

Hybrid polymer composites nowadays are increasingly used in many engineering products which are subjected to wear, dynamic mechanical and thermal applications. So in the present study, we have investigated the evaluation of dynamic mechanical, thermal and wear properties of vinyl ester hybrid composite strengthened with Ni-P coated E-glass fiber and Al₂O₃ nanowires as reinforcement at different concentrations. Nickel-Phosphorus is plated over the glass fiber substrate by means of the electroless plating method. The best optimum bath composition was determined after many trials and used for the proper plating process. From the outcome of the result, it is clear that the storage modulus has a trend to increase with increase in the concentration of Ni-P coated glass fiber (GF) and further increases when Al₂O₃ nanowires are used as the reinforcement. The glass transition temperature is also shifted to the higher temperature in the process. From the thermogravimetric analysis, it is clear that the thermal stability of the composite steps up with the addition of Al₂O₃ nanowires as fillers and Ni-P/GF as reinforcement. The wear properties are analyzed and the morphology of the coated and worn-out surfaces are studied by means of scanning electron micrographs and optical microscope images.

Electroless Deposition of Fe-Ni Alloy Thin Films for Power Semiconductor Package

Next generation power semiconductor such as silicon carbide (SiC) and gallium nitride (GaN) are known to have an excellent operation characteristic at high temperatures. The high temperature operation needs the power semiconductor package capable of withstanding greater thermal stress. The package for these devices requires a metallization process producing films with low coefficients of thermal expansion (CTEs) matching with the semiconductor and insulating substrates such as ceramics. The metallization by a wet process is expected to be beneficial because of its higher throughput and lower cost than that by dry and high temperature processes. Especially, electroless plating process is of current interest because it is also possible to form films metallized on non-conductive material such as an insulating substrate. Pyrometallurgically produced Fe-Ni alloys with 55 to 70 wt% Fe contents exhibited low CTEs. Therefore, electroless Fe-Ni alloy deposits can be also expected to have low CTEs comparable with those of semiconductor and insulating substrates used in power semiconductor devices. Although the literature contains several reports[1-3] that address the Fe-Ni alloys electrodeposition, the electroless Fe-Ni alloy deposition have not been sufficiently explored. In this study, we preliminary investigated the effect of electroless deposition condition on the alloy compositions, deposition rate, and morphologies of the electoless Fe-Ni alloy deposits. The optimum bath composition for electroless Fe-Ni alloy deposition was as follows: FeSO4 (0~0.02 mol/L), NiSO4(0.03~0.05 mol/L), potassium citrate (0.1 mol/L), potassium pyrophosphate (0.005 mol/L), and dimethylamine borane (0.025 mol/L). The bath temperature was 343 K and the bath pH was adjusted to pH 10.0. In the case of a pretreatment with Pd catalyst, although Fe-Ni alloy deposits were able to be deposited on a Cu substrate, the deposition rate was not enough. Therefore, the Fe-Ni alloy deposits were deposited on the Cu substrate connected with Al sheets to accelerate the deposition rate[4]. Fig. 1 shows effect of Fe2+/ (Fe2++Ni2+) concentration on alloy composition of electroless Fe-Ni alloy deposits and deposition rate for 1 h. The alloy composition was measured by EPMA. With increasing Fe2+/ (Fe2++Ni2+) concentration, Fe contents linearly increased to approximately 70 wt% and Ni contents linearly decreased to approximately 30 wt%. The B contents decreased with increasing Fe2+ concentration and were less than 1 wt% at Fe2+/ (Fe2++Ni2+) concentration of 0.2 or above. The deposition rate gradually decreased from 1.1 to 0.4 μm/h with increasing Fe2+ concentration. The appearance of the all deposits was smooth and uniform. The electroless Fe-Ni alloy deposits with from 0 to 40 wt% Fe contents exhibited bright, whereas those with Fe contents of 60 wt% or above exhibited dull gray. Fig. 2 shows FE-SEM images of the electroless Fe-Ni alloy deposits obtained for 1 h. The all deposits did not have any cracks. The primary particle size increased from several nm to approximately 50 nm with increasing Fe contents. The secondary particle size of all deposits was approximately 100 nm. In conclusion, the Fe-rich Fe-Ni alloy deposits with maximum Fe contents 70 wt% were obtained using dimethylamine borane as a reducing agent by electroless plating process; the electroless Fe-Ni alloy plating process may become an attractive metallization process for power semiconductor package. Acknowledgement This work was partially supported by the Kyoto Technoscience Center and Industry-Academia Collaborative R&D Programs “Super Cluster Program” (JST).

ELECTRODEPOSITION OF ZINC-NICKEL ALLOY IN THE PRESENCE OF LAWSONE ISOLATED FROM LAWSONIA INERMIS LINN LEAF

The electro deposition of zinc-nickel alloy was carried out in the presence of Lawsone (2-hydroxy1,4-napthoquinone) isolated from Lawsonia inermis Linn leaf. The bath constituents were optimized through Hull cell experiments. Operating parameters such as pH, temperature and current density were also optimized. The current efficiency and throwing power are measured at different current densities.SEM photomicrographs revealed fine-grained structure of the deposit from the optimum bath. IR spectrum of the scratched deposit showed inclusion of addition agent. XRD and EDAX studies revealed the inclusion of lawsone.

Synthesis and performance of Zn–Ni–P thin films**Project support by the Partnership Romanian Research Program (PNCDI2), CORZIFILM Project nr.72-221/2008-2011 and “EU (ERDF) and Romanian Government” that allowed for acquisition of the research infrastructure under POS-CEEO 2.2.1 project INFRANANOCHEM-Nr.19/01.03.2009.

The electroplating of Zn–Ni–P thin film alloys from a sulfate bath containing phosphoric and phosphorous acid was investigated. The bath composition and the deposition parameters were optimized through Hull cell experiments, and the optimum experimental conditions were determined (pH = 2, temperature = 298–313 K, zinc sulfate concentration = 30 g·L−1, EDTA concentration = 15 g·L−1, and current density, = ,1.0–2.0 A·dm−2). The SEM analysis of the coating deposited from the optimum bath revealed fine-grained deposits of the alloy in the presence of EDTA. Optical microscopy analysis indicated an electrodeposited thin film with uniform thickness and good adhesion to the steel substrate. The good adherence of the coatings was also demonstrated by the scratch tests that were performed, with a maximum determined value of 25 N for the critical load. Corrosion resistance tests revealed good protection of the steel substrate by the obtained Zn–Ni–P coatings, with values up to 85.89% for samples with Ni contents higher than 76%. The surface analysis of the thin film samples before and after corrosion was performed by X-ray photoelectron spectroscopy (XPS).

Effect of operatories parameters and elements composition of bath on the electroless copper deposition

The effect of operatories parameters and elements composition bath on deposition rate of electroless copper plating obtained from hypophosphite was investigated. It is found that the deposition rate increased significantly with increasing of nickel ions, acid boric and hypophosphite ions concentration and with pH value. Indeed, it is noted also that the deposition rate depend with temperature and the copper ions concentration. SEM/EDX analysis of the optimum bath showed that the deposit is generally homogeneous and presents a nodular structure and its composition contains 94.64 wt % of copper element and 5.36 wt% of nickel element. The XRD diffraction pattern of the film deposit showed that the deposit has a crystalline structure. So, the copper film with a higher (111) texture is preferred due to its higher reliability against electro-migration and lower electrical resistance.

Research on New Technology to Prepare Magnesium Hydroxide from Magnesium Sulphate

This work took Magnesium Sulfate (MgSO4) as raw material to research the influence of different surfactants and the concentration of the same surfactants on the final morphology of Magnesium Hydroxide (Mg(OH)2) in one-step synthesis process. And the analysis and characterization of the products by particle size analyzer and etc were also conducted. The research demonstrated that the polyethylene glycol would be the best surfactant, the optimum value for surfactant would be 3% of the obtained Mg(OH)2, and the optimum temperature water bath would be 50°C. With the above optimized condition parameters, the nanoscale Mg(OH)2procucts with flake morphology, high pure and well dispersion were obtained.

The Preparation and Application of Special Performance Ornamental Alloy Coating on Plastic Substrate

The electroless plating technics of copper on plastic substrate was researched, and on this basis, the Ni-W-P alloy plating technics on aforementioned plastic substrate was researched. The optimum electroless plating technics, plating technics and bath were found. The coating made in optimum technics was excellent in corrosion-resistance, wear-resistance, oxidation-resistance, and with a smooth, fine, shining surface. It was proved that the 8.1% phosphorus in the coating and the coating was amorphous crystal by determinations, the combination force between the substrate and the coating was very good, the properties of coating to resist corrosion and abrasion were 4 times better than that of Ni-P alloy by the tests. The coating was finery in ornamentally also.

Electroless Ni-P Plating on Mg-7Al Alloy by Chemical Conversion Pretreatment

Electroless Ni-P plating on Mg-7Al alloy by chemical conversion pretreatment was investigated. Morphology of electroless nickel plating coatings and phase compositions were measured by SEM, EDX and XRD. The optimized bath composition parameters were determined through orthogonal design. The morphology of electroless nickel plating coatings on Mg-7Al alloy exhibits a nodular structure and resembles the surface of a cauliflower and the coating is compact and consists of amorphous Ni-P coating. Potentiodynamic polarization curves of the Ni-P coatings in 3.5% NaCl show that the Ni-P coating extensively improves the corrosion resistance of Mg-7Al alloy and the highest corrosion potential reached to -0.54V vs. SCE(saturated calomel electrode). The results of the orthogonal experiment show that Nickel Sulfate of 25 g/L, Sodium Hypopho-sphate of 25 g/L and Citrate 7.5 g/L can be considered as the optimum bath content parameters for electroless Ni–P plating on Mg-7Al alloy and Nickel Sulfate has more effect on corrosion potential than Sodium Hypophosphate and Citrate..

Synergistic effect between nano-ceramic lubricating additives and electroless deposited Ni-W-P coating

The major solving ways for the material wear are surface modification and lubrication. Currently, the researches at home and abroad are all limited to the single study of either nano-lubricating oil additive or electroless deposited coating. The surface coating has high hardness and high wear resistance, however, the friction reduction performance of the coating with high hardness is not good, the thickness of the coating is limited, and the coating can not regenerate after wearing. The nano-lubricating additives have good tribological performance and self-repair function, but under heavy load, the self-repair rate to the worn surface with the nano-additives is smaller than the wearing rate of the friction pair. To solve the above problems, the Ni-W-P alloy coating and deposition process with excellent anti-wear, and suitable for industrial application were developed, the optimum bath composition and process can be obtained by studying the influence of the bath composition, temperature and PH value to the deposition rate and the plating solution stability. The tribological properties as well as anti-wear and friction reduction mechanism of wear self-repair nano-ceramic lubricating additives are also studied. The ring-block abrasion testing machine and energy dispersive spectrometer are used to explore the internal relation between the coating and the nano-lubricating oil additives, and the tribology mechanism, to seek the synergetic effect between the two. The test results show that the wear resistance of Ni-W-P alloy coating (with heat treatment and in oil with nano-ceramic additives) has increased hundreds times than 45 steel as the metal substrate in basic oil, the friction reduction performance is improved. This research breaks through the bottleneck of previous separate research of the above-mentioned two methods, and explores the combination use of the two methods in industrial field.

Electrodeposition and characterization of Ni–Zn–P and Ni–Zn–P/nano-SiC coatings

Alloy coatings and metal based composites have been given special attention for their unique properties. In the present study, a novel electroplating bath was introduced. Ni–Zn, Ni–Zn–P nickel rich alloy coatings and Ni–Zn–P/nano-SiC nickel rich composite coating were successfully deposited on low carbon steel substrates. The optimum bath composition was found by comparing the amount of coating cracks checked by a scanning electron microscope (SEM). The presence of nearly homogeneous SiC nanoparticles in the coating was confirmed by field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and MAP analysis. The effect of operating conditions on the mechanical properties of nanocomposite coatings was investigated. The wear resistance of the coatings was examined by pin on disk wear tests. The nanocomposite coatings had a lower weight loss compared to the Ni–Zn–P coatings in the wear test.

The effect and mechanism of Nano-Cu lubricating additives on the electroless deposited Ni-W-P coating

The coating and deposition process with excellent anti wear and suitable for industrial application were developed, and the optimum bath composition and process were obtained by studying the influence of the bath composition, temperature and pH value on the deposition rate and the plating solution stability. Moreover, the tribological properties of nano-Cu lubricating additives and electroless deposited Ni-W-P coating as well as their synergistic effect are researched using ring-block abrasion testing machine and energy dispersive spectrometer. Research results show that Ni-W-P alloy coating and nano-Cu lubricating additive have excellent synergistic effect, e g, the wear resistance of Ni-W-P alloy coating (with heat treatment and the oil with nano-Cu additives) has increased hundreds times than 45 steel as the metal substrate with the basic oil, and zero wear is achieved, which breaks through the bottleneck of previous separate research of the above-mentioned two aspects.

Modeling the electroless nickel deposition on aluminum nanoparticles

In this study, Ni coated aluminum nanoparticles were fabricated by electroless nickel deposition. Effect of two groups of parameters on the process plating rate were investigated: bath composition (main salt, reducing agent and complexing agent concentration) and process parameters (pH, plating time and bath temperature). Simulation of the process was performed using artificial neural network (ANN) media. Based on the presented model it is possible to design a high efficiency electroless bath, while minimum received materials are used and maximum plating rate is obtained. According to the model's results, 0.07mol/l NiSO4·2H2O, 0.245mol/l NaH2PO2·H2O and 0.098mol/l Na3C6H5O7·H2O were chosen as the optimum electroless bath composition. The optimum bath parameters also were selected as pH of 9.5, temperature of 80°C and 30min of plating. At such condition, the most efficient Ni deposition, with maximum plating rate of 45%, was acquired on the surface of aluminum particles. These samples were characterized by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results showed that a low phosphorus and nanocrystalline Ni layer, with about 30nm thickness, has been coated on the aluminum nanoparticles.