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1 – 10 of 257This paper aims to report a study of the influence of tungsten carbide (WC) nanoparticles on corrosion resistance properties of electroless nickel–phosphorus (Ni–P) coatings in…
Abstract
Purpose
This paper aims to report a study of the influence of tungsten carbide (WC) nanoparticles on corrosion resistance properties of electroless nickel–phosphorus (Ni–P) coatings in NaCl solution.
Design/methodology/approach
The morphology of Ni–P–WC nanocomposite coatings was observed by scanning electron microscopy (SEM). The anodic polarization curves, electrochemical impedance spectra (EIS) and weight loss measurements were used to study the corrosion resistance properties of Ni–P–WC nanocomposite coatings in NaCl solution.
Findings
The WC nanoparticles content in the coatings increased with the increase of its concentration in the bath, and the WC nanoparticles are uniformly distributed in Ni–P alloy matrix. The results showed that the incorporation of WC nanoparticles elevated the corrosion resistance properties of Ni–P alloy matrix.
Originality/value
This study shows that the corrosion resistance was improved by the addition of WC nanoparticles to the Ni–P alloy matrix.
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Haiqiang Yu, Quanzhong Guo, Keqin Du, Dongyun Li, Chuan Wang and Yong Wang
The purpose of this paper is to investigate the interfacial conductivity and corrosion resistance of the Ni–P/Ti4O7 composite coating that is deposited on a carbon steel substrate…
Abstract
Purpose
The purpose of this paper is to investigate the interfacial conductivity and corrosion resistance of the Ni–P/Ti4O7 composite coating that is deposited on a carbon steel substrate as bipolar plates for proton exchange membrane fuel cells.
Design/methodology/approach
The Ni–P/Ti4O7 coating was prepared by electroless plating. Scanning electron microscopy, white light interference, energy dispersive spectrometry and X-ray diffraction were used, respectively, to study the surface morphology, chemical composition and phase composition of coated samples. Electrochemical impedance spectroscopy, potentiodynamic and potentiostatic polarization were used to test the electrochemical performance and corrosion behavior. The interfacial contact resistance (ICR) was measured via the standard method.
Findings
The surface of the Ni–P/Ti4O7 coating is complete and dense and without obvious defects. The electrochemical test results show that the Ni–P/Ti4O7 coating provides better corrosion resistance than the Ni–P coating and substrate. Compared with the Ni–P coating, the ICR of the Ni–P/Ti4O7 coating is lower by about 82.7%. This is because the coating has more conductive contact points. The more exciting thing is that the ICR of the Ni–P/Ti4O7 coating only increases to 12.38 mΩ·cm2 after 5 h of polarization.
Originality/value
This paper provides a method for achieving surface modification of metal bipolar plates. Introducing Ti4O7 particles in the Ni–P layer reduces the contact resistance before and after polarization while ensuring good corrosion resistance.
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Dezhi Li, Changqing Liu and Paul P. Conway
To study the influence of storage time and environment on the solderability of electroless nickel plated samples with Sn‐3.8Ag‐0.7Cu and Sn‐3.5Ag lead‐free solders and to provide…
Abstract
Purpose
To study the influence of storage time and environment on the solderability of electroless nickel plated samples with Sn‐3.8Ag‐0.7Cu and Sn‐3.5Ag lead‐free solders and to provide criteria for the use of an electroless nickel (Ni‐P) under bump metallization (UBM) without immersion gold protection.
Design/methodology/approach
Electroless nickel coatings were deposited onto pure aluminium foil through a procedure developed for the UBM of wafers prior to flip chip bumping. Their solderability with lead‐free solders was studied using the wetting balance technique. Samples stored in different environments for different periods of time were tested to study the dependence of the solderability of Ni‐P coatings on the storage time and temperature. The degree of oxidation of the Ni‐P coatings was examined by means of X‐ray photoelectron spectroscopy and the surface microstructure and roughness of the coatings were analyzed by scanning electron microscopy and atomic force microscopy.
Findings
It was found that the Ni‐P coatings were unacceptable for direct soldering without the assistance of a flux, due to poor wettability, even when using a freshly prepared Ni‐P coating. Therefore, a suitable flux with nitrogen inerting had to be applied to assist the soldering process. The results also show that the solderability of Ni‐P coatings was affected by the phosphorus content, and the Ni‐P coating with high phosphorus content had a good solderability. The storage time and temperature did not influence the wettability significantly with the assistance of strong flux.
Research limitations/implications
The stability of the plating solution and the consistence of the phosphorus content in the coating are not easily controlled. This has resulted in implications for surface analysis and wetting testing. Ni‐P coatings with different levels of phosphorus content are being investigated in detail.
Originality/value
The value of the paper lies in its study on the solderability of lead‐free solders to Ni‐P coating after storage in different environments and for different periods, which can provide some criteria for the use of Ni‐P UBM without immersion gold protection.
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Fei Li, Yulin Yang, Laizhou Song and Lifen Liang
The purpose of this paper is to elucidate the tribology behavior of polytetrafluoroethylene (PTFE) incorporated with three types of nickel–phosphorus (Ni-P) particles (i.e. low…
Abstract
Purpose
The purpose of this paper is to elucidate the tribology behavior of polytetrafluoroethylene (PTFE) incorporated with three types of nickel–phosphorus (Ni-P) particles (i.e. low phosphorus [LP], medium phosphorus [MP] and high phosphorus [HP]) under dry sliding condition.
Design/methodology/approach
Ni-HP, Ni-MP and Ni-LP particles fabricated via an electroless plating process were incorporated into PTFE matrix with different additions to prepare Ni-P/PTFE composites (Ni-LP/PTFE, Ni-MP/PTFE and Ni-HP/PTFE). The tribology tests for these samples were carried out on a reciprocating ball-on-disc tribometer. The thermal stabilities, mechanical and tribological properties, morphologies and components of aforesaid Ni-P/PTFE composites were analyzed.
Findings
The marvelous effect of Ni-P incorporation on the simultaneous reduction in friction and wear of PTFE was corroborated.
Originality/value
Compared with that of pristine PTFE sample, the reduction on friction with a value of 27% and the reduction in wear about 94% for Ni-HP/PTFE composite is validated, which is probably related to the increased crystallinity and hardness due to the presence of Ni-P particles.
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Refaie Omar, Elsayed Oraby, Yasser Abdelrhman and Mohammed Aboraia
The ability to produce a uniform composition, high corrosion resistance with a hard coating layer during the electroless coating techniques are mainly based on the plating bath…
Abstract
Purpose
The ability to produce a uniform composition, high corrosion resistance with a hard coating layer during the electroless coating techniques are mainly based on the plating bath composition. The complexing agent is one of the most important components that control the coating layer properties. This paper aims to investigate the effect of the glycine as a complex agent on the surface and corrosion properties of Ni-P and Ni-P/Al2O3 electroless coating.
Design/methodology/approach
In this study, the effect of glycine as a complexing agent on the final surface and corrosion properties of the Ni-P and Ni-P/Al2O3 coatings has been investigated. The surface morphology and composition of the coated samples were investigated by scanning electron microscope (SEM) imaging and energy dispersive x-ray spectroscopy (EDS) analysis. Linear polarization scan and electrochemical impedance spectroscopy techniques were used to investigate the corrosion properties of the coating layer.
Findings
The results clarify that, glycine has a remarkable effect on the porosity content of Ni-P and Ni-P/Al2O3. It was found that increasing of glycine concentration results in higher porosity content in the coating layers. Also, the porosity in the coating layers minimizes the protectability of the coating against corrosion. The results also show that adding nano-alumina (Al2O3) to the coating path has improved the corrosion properties by decreasing the porosity in the coating layer. The scanning electron microscope (SEM) images showed that the concentration of glycine affects the content and distribution of alumina nanoparticles embedded in the coating layer. Also, it was observed that using a high concentration of glycine (0.4 M glycine), the alumina tends to agglomerate and the final alumina content in the coating was decreased.
Originality/value
The present study reveals that the quality of the final coating plays a major role in the corrosion performance of the steel substrate. The coating quality can by improve remarkably by optimization of the complexing agent used in the plating bath, to minimize the porosity involve in the coating layer.
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Z. Abdel Hamid and A. Abdel Aal
The purpose of this paper is to investigate the deposition of uniform, adherent and crack‐free Ni‐P thin films on carbon fibres using the electroless deposition technique.
Abstract
Purpose
The purpose of this paper is to investigate the deposition of uniform, adherent and crack‐free Ni‐P thin films on carbon fibres using the electroless deposition technique.
Design/methodology/approach
Before applying the electroless process, the carbon fibre surfaces must be subjected to several treatment processes to remove the organic binder, etching and surface metallization. The surface morphology of the Ni‐P coatings was assessed using a scanning electron microscope (SEM). The chemical compositions of Ni‐P layers were identified by energy dispersive X‐ray analysis (EDS). The bond strength of the coated layer was determined by measuring the electrical resistance at the fibre/coating interface. The magnetic properties of the fibres were estimated using a hysteresis diagram. The tensile performance of single fibres coated by Ni‐P has been investigated with respect to coating thickness.
Findings
Pre‐treatment processes are used to improve the adhesion of Ni‐P layers and to obtain homogeneous coatings. The influence of plating parameters (temperature, pH and time) on the coating thickness of the Ni‐P layer was investigated. It was found that the coating thickness increased as the pH value, plating time and the temperature of the bath increased. The results revealed that a complete and uniform Ni‐P coating on fibre could be obtained at optimum conditions 85°C, pH 6, for 60 min, and the results indicated that the P content in the electroless deposit is approximately 3.4 wt%. The tensile strength values are improved significantly after coating and increased by 3‐5 times with increasing of coating thickness from 0.3 to 2 μm.
Originality/value
The results presented in this work are an insight into understanding of the deposition and adherence of Ni‐P thin films on carbon fibre using the electroless technique and behaviour of the coated fibre.
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P. Kowalik, Z. Pruszowski, J. Kulawik, Andrzej Czerwiński and Mariusz Pluska
This paper aims to select parameters such as temperature thermal stability and temperature coefficient of resistance (TCR) for Ni–P resistive alloys obtained by electroless…
Abstract
Purpose
This paper aims to select parameters such as temperature thermal stability and temperature coefficient of resistance (TCR) for Ni–P resistive alloys obtained by electroless metallization. Ni–P alloys are used in the manufacture of precision resistors characterized by TCR in the range of ± 10 ppm/K. The correlation of the technological parameters with the electrical properties of resistors enables the accurate prediction of the TCR resistors.
Design/methodology/approach
The Ni–P layers were obtained by a continuous process at about 373 K in a solution with the acidity of pH = 2 and then dried for two hours at 393 K. Subsequently, the Ni–P layer was stabilized for two hours in the temperature range of 453-533 K. Resistance was measured with an accuracy of 1 mΩ. TCR was determined with an accuracy of 1 ppm/K in the temperature range 298-398 K. In the next stage of the investigation, the increase in TCR of the Ni–P alloy was correlated with the increase in stabilization temperature. Scanning electron microscope images of the alloy surface were studied to assess grain sizes and to relate the average grain size with TCR values of resistive alloys. The X-ray diffraction analysis was performed to determine the crystallization temperature of Ni–P alloy.
Findings
The conducted investigation showed that the TCR increase in alloy is a linear function of stabilization temperature in the temperature range in which transition from amorphous phase to crystalline phases did not occur. TCR increase in Ni–P alloy arises from the increase of average size of grains resulting in decrease of scattering of electrons on grain boundaries. The analysis of alloy composition in chosen fragments of surface shows inhomogeneity growing with decreasing analyzed surface dimensions which proves that, before the stabilization, the structural arrangement of alloy is inconsiderable.
Originality/value
The obtained results are the first attempt to relate the morphology of surface with TCR of alloy and demonstration of linear dependence between an increase in TCR of amorphic Ni–P alloy and stabilization temperature of resistive layer. Such correlations are not described in available literature.
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Thimmappa Venkatarangaiah Venkatesha and Sudhakar Ranganatha
The purpose of this paper is to evaluate the corrosion resistance of the electroless Ni‐P coatings in two aggressive media 3.5 wt.% NaCl and Synthetic industrial waste water. Also…
Abstract
Purpose
The purpose of this paper is to evaluate the corrosion resistance of the electroless Ni‐P coatings in two aggressive media 3.5 wt.% NaCl and Synthetic industrial waste water. Also to study the effect of Phosphorous content in the electroless Ni‐P deposits on its surface nature, morphology and corrosion resistance.
Design/methodology/approach
The corrosion behavior of electroless Ni‐P coatings generated on mild steel coupons from an acidic and an alkaline baths and their anti‐corrosion performance of was compared systematically in 3.5 wt.% of NaCl solution and also in synthetic industrial waste water. Microstructure and surface composition of coatings were analyzed using X‐ray diffraction, scanning electron microscopy and energy dispersive spectroscopy techniques, respectively. The Ni‐P coated mild steel specimens were subjected to corrosion and the rate of corrosion was studied by chemical and electrochemical methods. The linear sweep voltammetry, Tafel and electrochemical impedance spectroscopy were employed to obtain corrosion data.
Findings
The electroless Ni‐P coatings with higher P content possess homogeneous, uniform and amorphous surface nature and exhibited higher corrosion resistance in the aggressive corrosive media chosen.
Originality/value
This paper provides corrosion behavior of electroless Ni‐P coatings in 3.5 wt.% NaCl and synthetic industrial waste water, and establishes the importance of phosphorous content on nature and properties of the coatings.
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Wojciech Filipowski, Zbigniew Pruszowski, Krzysztof Waczynski, Piotr Kowalik and Jan Kulawik
The paper aims to present a research on the impact of the stabilization process of a thin metallic layer (Ni-P) produced on a ceramic surface (Al2O3) by means of electroless…
Abstract
Purpose
The paper aims to present a research on the impact of the stabilization process of a thin metallic layer (Ni-P) produced on a ceramic surface (Al2O3) by means of electroless metallization on its electric parameters and structure. On the basis of the research conducted, the existence of a relationship between resistance (R) and the temperature coefficient of resistance (TCR) of the test structure with a Ni-P alloy-based layer and the temperature of stabilization was proposed.
Design/methodology/approach
Metallic Ni-P layers were deposited on sensitized and activated substrates. Metallization was conducted in an aqueous solution containing two primary ingredients: sodium hypophosphite and nickel chloride. The concentration of both ingredients was (50-70) g/dm3. The process lasted 60 min, and the metallization bath pH was kept at 2.1-2.2, whereas the temperature was maintained at 363 K. The thermal stabilization process was conducted in different temperatures between 453 and 623 K. After the technological processes, the resistance and TCR of the test structures were measured with a micro ohmmeter. The composition and the morphology of the resistive layer of the structures examined was also determined.
Findings
The dependence of the resistance on the temperature of the stabilization process for the temperature range 553 to 623 K was described using mathematical relationships. The TCR of test resistors at the same thermal stabilization temperature range was also described using a mathematical equation. The measurements show that the resistive layer contains 82.01 at.% of nickel (Ni) and 17.99 at.% of phosphorus (P).
Originality/value
The results associate a surface morphology Ni-P alloy with the resistance and TCR according to temperature stabilization. The paper presents mathematical relationships that have not been described in the literature available.
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Z. Pruszowski, P. Kowalik, M. Cież and J. Kulawik
The purpose of this paper is to characterize electrical parameters of amorphous Ni‐P resistive layers used for fabrication of precise resistors.
Abstract
Purpose
The purpose of this paper is to characterize electrical parameters of amorphous Ni‐P resistive layers used for fabrication of precise resistors.
Design/methodology/approach
Ni‐P resistive layers were produced by the chemical process in water solution using Ni2 + and H2PO2− ions. The paper presents the results of the studies concerning the influence of bath acidity and conditions of thermal stabilization on the structure and temperature coefficient of resistance of Ni‐P alloy.
Findings
The temperature coefficient of resistance of amorphous Ni‐P layers was found to depend significantly on the parameters of chemical metallisation process. It was stated that the changes of through‐casing resistivity versus the acidity of technological solution have roughly parabolic characteristics.
Originality/value
In this paper, it was at first explained how the changes of the structure of Ni‐P resistive layers depend on their temperature coefficient of capacitance.
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