Journal ArticleDOI
Evaluation of the corrosion resistance of electroless Ni-P and Ni-P composite coatings by electrochemical impedance spectroscopy
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TLDR
In this paper, the same fundamental reaction is occurring on all the coatings of the present study but over a different effective area in each case, which can be attributed to the decrease in the effective metallic area prone to corrosion.Abstract:
Electroless Ni-P composite coatings have gained a good deal of popularity and acceptance in recent years as they provide considerable improvement of desirable qualities such as hardness, wear, abrasion resistance, etc. The disagreement among researchers on the corrosion behaviour of these coatings warrants a thorough investigation. Among the various techniques available for the determination of corrosion resistance, electrochemical impedance spectroscopy (EIS) is considered to be superior as it provides not only an assessment of the corrosion resistance of different deposits but also enables the mechanistic pathway by which the deposits become corroded to be determined. The present investigation focuses on the evaluation of the corrosion resistance of electroless Ni-P and Ni-P-Si3N4, Ni-P-CeO2 and Ni-P-TiO2 composite coatings produced using an acidic hypophosphite-reduced electroless nickel bath, using EIS. The study makes evident that the same fundamental reaction is occurring on all the coatings of the present study but over a different effective area in each case. The charge transfer resistance of electroless Ni-P and Ni-P composite deposits are in the range 32,253–90,700 Ω cm2, whereas the capacitances of these coatings are in the range 11–17 µF/cm2. The improved corrosion resistance obtained for electroless Ni-P and Ni-P composite coatings is due to the enrichment of phosphorus on the electrode surface, which enables the preferential hydrolysis of phosphorus over that of nickel. The better corrosion resistance obtained for electroless Ni-P composite coatings can be ascribed to the decrease in the effective metallic area prone to corrosion. Among the three electroless Ni-P composite coatings, the corrosion resistance is in the following order: Ni-P-CeO2=Ni-P-Si3N4>Ni-P-TiO2.read more
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Journal ArticleDOI
Influence of the Tungsten Content on Surface Properties of Electroless Ni-W-P Coatings
Mara Cristina Lopes de Oliveira,Olandir Vercino Correa,Bardia Ett,Isaac Jamil Sayeg,Nelson Batista de Lima,Renato Altobelli Antunes +5 more
TL;DR: In this article, ternary Ni-W-P films were produced by electroless deposition using baths with different tungsten concentrations, and the coated surfaces were annealed at 400°C for 1h.
Journal ArticleDOI
Electroless Deposition of Ni-Cu-P Coatings Containing Nano-Al2O3 Particles and Study of Its Corrosion Protective Behaviour in 0.5 M H2SO4
TL;DR: In this paper, Ni-Cu-P/nano-Al2O3 composite coatings are prepared on mild steel from an alkaline electroless plating bath containing different concentrations of nano-Al 2O3 nanoparticles.
Journal ArticleDOI
Development of nano NiO incorporated nickel–phosphorus coatings for electrocatalytic applications
TL;DR: In this article, the effects of nano NiO incorporation on enhancement of electrocatalytic efficiency of the electroless Ni-P coatings for hydrogen evolution reactions (HERs) in alkaline medium were systematically investigated.
Journal ArticleDOI
Wear and Corrosion Resistance of Electroless Nickel-Boron Coated Mild Steel
TL;DR: Nickel-boron coatings were synthesized on mild steel by the electroless deposition method and some of the coatings are submitted to a hardening heat treatment at 400°C during 1 hour in an atmosphere containing 95% Ar and 5% H2 as mentioned in this paper.
References
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Journal ArticleDOI
The anodic behavior of amorphous Ni-19P alloys in different amorphous states
Hiroki Habazaki,Shao-Qien Ding,Asahi Kawashima,Katsuhiko Asami,Koji Hashimoto,Akihisa Inoue,Tsuyoshi Masumoto +6 more
TL;DR: In this article, an amorphous Ni-19P alloy prepared by rapid quenching of white heat melt showed a higher anodic dissolution current density in 1 N HCl in comparison with the same amorphized alloy prepared with red heat melt, showing that the difference in anodic behavior between these two as-quenched specimens seems due to the differences in the amounts of quenched-in defects.