Papers by Keyword: Ni-P Coating

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Authors: Shazlin Shaik Osman, Mohd Sharif Nurulakmal
Abstract: When the use of lead was banned, the development of lead-free solders began to rise and was greatly explored. Presently, majority of the eutectic Pb-free solders are Sn-based and the most promising is ternary SnAgCu (SAC) solder. However, SnAgCu solder tends to become brittle in nature and excessive solder interfacial reactions. An attractive approach is by introducing alloying elements such as Ce, Fe and Zn into the SnAgCu solder, which allows for an increase of the mechanical properties and refine the solder microstructure as well as improve the wetting properties. The present work focuses on the effects of a series of elemental additions of 0.5% Ce, Fe and Zn into the basic Sn3.0Ag0.5Cu solder, in attempt to reduce the intermetallic compound (IMC) growth as well as joint reliability and reflow properties of the solder on Ni-P surface finish. The intermetallic compound Cu6Sn5, containing a small amount of dissolved Ni, was found to form preferentially on the Ni coating. This compound layer served as a barrier for direct reaction of Sn with the Ni-P coating. The P-rich Ni layer acts as a good diffusion barrier layer, which decreases the dissolution rate of the Ni-P layer hence decreases the growth of IMC thickness layer. It is also expected that with the addition of alloying elements, the wetting properties will be further enhanced.
Authors: Chun Yu Wang, Huan Ran Li, Wei Zhang, Yang Yu, Guang Wu Wen
Abstract: The post-treatment with Ce-rich sealing of Ni-P coating (Ce-sealed Ni-P coating) was developed on Al surface. Effects of corrosion resistance with different phosphorus contents in the Ni-P coatings were investigated in this paper. The results of the polarization curves show that the Ce-sealed Ni-(10wt.%)P coatings have the higher corrosion potential (Ecorr) and the lower corrosion current (icorr), indicating that this coating iSubscript texts a better corrosion inhibitor than Ni-(3wt.%)P coating. These results demonstrate that the P content plays an obvious role on improving the corrosion resistance of Ni-P coatings. It is results of SEM analysis shows that the Ce-sealed Ni-(3wt.%)P coating has not obvious micro-cracks, the Ce-sealed Ni-(10wt.%)P surface with some micro-cracks are appeared on Ce-rich coating. But this micro-cracks phenomenon of Ce-rich coating can not effect on corrosion resistance. Otherwise, there are no peaks of Ce-riched coatings in both XRD patterns, because too less Ce elements and non-crystal tendency is more serious on these coatings.
Authors: Magdalena Popczyk, B. Łosiewicz, Eugeniusz Łągiewka, A. Budniok
Abstract: The Ni-P, Ni-Co-P and Ni-P+Co coatings were obtained in galvanostatic conditions at the current density of jdep= -200 mA cm-2. A stereoscopic microscope was used for surface morphology characterization of the coatings. The X-ray diffraction (XRD) method was used to determine phase composition of the coatings and the atomic absorption spectrometry (AAS) was applied to specify their chemical composition. The behavior of the obtained coatings was investigated in the process of hydrogen evolution reaction (HER) from 5 M KOH using steady-state polarization and electrochemical impedance spectroscopy (EIS) methods. It was found that introduction into Ni-P amorphous matrix powder of cobalt produced porous electrode materials which could be used for the HER.
Authors: Ai Xiang Zeng, Kai Long Hu, Li Luo
Abstract: Electroless Ni- P-coating of fly-ash cenosphere particles is demonstrated in the present investigation. The Electroless Ni- P-coating process is modified by replacing the conventional sensitization and activation steps with only using activation step with CuSO4 activator. The cenosphere particles are characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDX), X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscopy (XPS) during and after the coating process. Relatively uniform and continuous coating is obtained under the given coating conditions. The possible mechanism of electroless Ni-P-coating of cenosphere particles utilizing CuSO4 activator is suggested. The low density Ni-P coated cenosphere particles may be utilized for manufacturing conducting polymers for EMI-shielding application and microwave absorbing materials.
Authors: Arman Zarebidaki, Saeed Reza Allahkaram
Abstract: Ni-P/nano- SiC composite coatings were deposited in different concentrations of SiC nano-particles in the bath. The hardness and corrosion resistance of the composite coatings with different content of SiC nano-particles were measured. Moreover, the structure of the composite coatings was investigated by means of X-ray diffraction (XRD), while their morphologies and elemental composition were analyzed using scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). Results showed that co-deposited SiC nano-particles contributed to increase the hardness but corrosion resistance of electroless Ni-P coatings decreased due to agglomeration of nano-particles and increasing porosity of coatings.
Authors: Guo Bing Mao
Abstract: The Ni-P coatings were deposited on AM60 magnesium alloy by electroless plating process without or with accelerators. Without accelerators, the deposition rate is slow and required high bath temperature to obtain compact coating. There have many defects on the surface of the Ni-P coatings which deposited at high bath temperature. The composite accelerators were introduced into the bath for improving the growth rate and the quality of the Ni-P coating. Uniform, with no pores or cracks, “cauliflower-like” structure and complete Ni-P coatings were deposited only taken 20 min with additives at low bath temperature. The XRD result indicates that the structure of the Ni-P coating is amorphous nickel. The corrosion test results indicated that the corrosion resistance of this coated AM60 magnesium alloys increases distinctly as compared to bare alloys.
Authors: Peng Zhang, De Ren Wang, Ye Dong He
Abstract: Cathodic plasma electrolysis (CPE) is an emerging surface engineering technology in the recent years. In present work CPE was successfully used for deposition Ni-P coatings on carbon steel. The deposition experimental results show that CPE possesses high coating deposition rate, faster than 4 μm/min. SEM observations unveil the bonding between Ni-P coating and substrate is metallurgical. XRD diagram analysis indicates that the phases of as-deposited Ni-P coating are Ni and Ni3P, transformed from amorphous to crystallized state. The corrosion resistances of CPE and electroless plating (EP) coating have also been discussed by polarization curves in 3.5% NaCl solution at room temperature. Scratch tester was applied to study film-substrate adhesion of CPE Ni-P coating comparing with EP Ni-P coating.
Authors: Xian Guo Hu, Wen Ju Cai, Jiu Cong Wan, Yu Fu Xu, Xiao Jun Sun
Abstract: The electroless nickel-phosphor coatings containing molybdenum disulfide nanoparticles were prepared and analyzed in this paper. The effects of incorporation of MoS2 into the Ni-P coating on the morphology of the coating surface and corrosion properties were also studied. Corrosion tests were conducted inside a salt spray box with NaCl solution (5.0 wt%). The corrosional surfaces were studied and analyzed through optical microscope, X-ray spectrometer (XRD) and scanning electron microscopy (SEM). The investigation on the relationship between heat-treatment and the corrosion resistance of the coatings showed that the corrosion resistance of the composite coating became worse because of the occurrence of transformation from non-crystalline to crystalline, and then increased the metastable intergradation of the composite coating. Meanwhile, the experimental results also showed that corrosion resistance of the coating containing MoS2 was higher than that of steel substrate. The corrosion mechanism of the composite coatings was mainly ascribed to the formation of micro-cell around the nanosized MoS2 particles, and the active ion like Cl- destroyed the surface film and induced the corrosion towards the inside part of coating.
Authors: Long Hao, Ye Ming Zhang, Chao Yang, Hua Zhu, Xu Hui Mao, An Lin, Fu Xing Gan
Abstract: With suitable pretreatment, a compact and even nickel-phosphorus alloy coating was obtained on W-Cu alloy by electroless deposition from solutions containing nickel sulphate as a source of nickel and sodium hypophosphite as the reducing agent and a source of phosphorus. The Ni-P coating was normally prepared from acidic baths at high temperature of the order of 90oC with the pH of 4.8 and it was smooth and uniform and exhibited high crystal refinement and high microhardness and superior corrosion resistance. The microhardness, adhesion and corrosion resistance mechanism of Ni-P deposit were studied. The microhardness of the Ni-P alloy deposit increases greatly by tempering at various temperatures. The Ni-P deposit has a strong adhesive force with W-Cu alloy substrate checked by thermal shock test and scribe test. The anti-corrosion ability of Ni-P coating and its anti-corrosion mechanism were measured using immersion experiment and potentiodynamic polarization techniques. The results showed that the corrosion resistance of Ni-P coating was higher than that of W-Cu alloy substrate in the 10vol.% sulfuric acid, monitoring sweat solution and 3.5wt.% sodium chloride solution. The anti-corrosion mechanism of electroless Ni-P coating immersed in 3.5wt.% sodium chloride solution was studied using potentiodynamic polarization techniques. The surface micromorphological morphology and structure of the Ni-P coating were investigated using Scanning Electronic Microscope (SEM) and X-ray Diffraction (XRD). The results indicated that the Ni-P alloy coating consisted of microcrystals and it was amorphous in structure, and the electrochemical measurement showed passive film formed on Ni-P coating during immersion test in the 3.5wt.% sodium chloride solution.
Authors: Zhao An, Ming Ya Li, Nian Hao Ge, Xiao Ying Li, Qiu Fan Li, Min Chen
Abstract: In this paper, the method of electroless deposition of nickel-phosphorous composite coating on the sample surface is employed. The effect of the complexing agent ratio on the surface morphology and phase composition of nickel-phosphorus coating when the main salt and reducing agent concentration unchanged has been studied. The influence of heat treatment on properties and microstructure of coatings are also investigated. Experimental results show that in the case of salt and reducing agent concentration unchanged, complexing agent concentration has strong effect on the morphology of the coatings and the crystal structure of the composite coating. During heat treatment, the morphology of the composite coating changed significantly, and the hardness was improved a certain degree for all the samples, which is related to the precipitation of Ni3P.
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