Formation and characterization of borohydride reduced electroless nickel deposits
TL;DR: In this article, the formation of electroless Ni-B deposits and evaluation of their characteristic properties were studied. And the corrosion resistance of Ni-b deposits, in 3.5% sodium chloride solution, both in as-plated and heat-treated (450°C/1 h) conditions, was also evaluated by potentiostatic polarization and electrochemical impedance studies.
About: This article is published in Journal of Alloys and Compounds.The article was published on 2004-02-25. It has received 136 citations till now. The article focuses on the topics: Electroless nickel & Nickel boride.
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TL;DR: In this article, the electroless coating of Ni-B nanolayer on B4C particle surfaces was studied and the effect of activation agent PdCl2, complexing agent C2H8N2, and reducing agent NaBH4 addition rate were investigated.
Abstract: This work is focused on electroless coating of Ni–B nanolayer on B4C particle surfaces The B4C particles used are approximately 2 μm in average size Effects of activation agent PdCl2, complexing agent C2H8N2, and reducing agent NaBH4 addition rate are studied The solids loading of B4C is 0625 g/L and the concentration of Ni2+ ions is 0004 mol/L in the electroless coating solution Scanning electron microscopy (SEM) shows that when B4C:Pd2+ molar ratio is 1:0005, a Ni–B nanolayer with the smallest Ni–B nodule size covers the B4C particle surfaces Complexing agent C2H8N2 decreases Ni2+ ion release rate Ni:C2H8N2 ratio of 1:6 is the preferred complexing agent amount for achieving a continuous Ni–B nanolayer The Ni–B nanolayer formation is also strongly dependent on the rate that Ni2+ ions are reduced Slow Ni2+ reduction leads to increased Ni content in the Ni–B nanolayer When the above three factors are combined at the optimal values for the electroless coating process, well-defined Ni–B nanolayer is obtained SEM cross section analysis shows the Ni–B nanolayer completely covers the B4C particles with less than 55 nm thickness
24 citations
TL;DR: In this article, a microstructure-based guideline for designing an optimal heat treatment scheme has been proposed to evaluate the tribo response of the coating as a function of coating's microstructures.
24 citations
TL;DR: In this paper, the capability of dynamic chemical plating (DCP) to deposit both binary (Ni-P) and ternary nickel alloys (NiP-B) is evaluated.
23 citations
TL;DR: Ni-B coatings have been deposited directly on commercial purity magnesium and AZ91D magnesium alloy by a chromium-free electroless process and characterized using scanning electron microscopy, glow discharge optical emission spectroscopy, gravimetric measurements and, for corrosion evaluation, hydrogen evolution as mentioned in this paper.
Abstract: Ni–B coatings have been deposited directly on commercial purity magnesium and AZ91D magnesium alloy by a chromium-free electroless process and characterized using scanning electron microscopy, glow discharge optical emission spectroscopy, gravimetric measurements and, for corrosion evaluation, hydrogen evolution. The surfaces of the coatings reveal a typical cauliflower-type appearance and form at a rate of ~ 8 to 13 μm/h. The nickel and boron contents of the coatings are relatively uniform across the whole thickness. The addition of NH 4 HF 2 to the electroless bath improves the corrosion resistance provided by the coatings during immersion of coated substrates in sodium chloride solution.
23 citations
TL;DR: In this paper, the corrosion resistance of electroless (EL) Ni-low B coatings, obtained using an alkaline borohydride-reduced electroless plating bath, with varying concentrations of NaBH4 (0·2−1·0 g L−1), in 3·5%NaCl, was evaluated.
Abstract: The corrosion resistance of electroless (EL) Ni–low B coatings, obtained using an alkaline borohydride-reduced electroless plating bath, with varying concentrations of NaBH4 (0·2–1·0 g L−1), in 3·5%NaCl, was evaluated. The rate of deposition, boron content and the size of the nodules of the EL Ni–low B coatings were increased while the crystallinity of the coating was decreased with increasing concentration of NaBH4. The change in chemical composition and decrease in crystallinity did not seem to have any influence on the corrosion resistance of the EL Ni–low B coatings of the present study, as opposed to the nodular growth with a columnar structure which had a profound effect. The results of polarisation and electrochemical impedance spectroscopy (EIS) studies confirm penetration of the corrosive medium through the columnar nature of the coating and ascertain its dominating influence on the corrosion resistance of EL Ni–low B coatings over other factors. The results of the present study again co...
23 citations
References
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Book•
01 Jan 1990
TL;DR: The Electroless Plating: Fundamentals and Applications (ESPA) as discussed by the authors is a comprehensive text that covers both fundamental and applied aspects of electroless deposition, and was first introduced at SUR/FIN '91.
Abstract: Many texts have been written on surface finishing over the years that deal with electroless deposition as a sidelight. Through the talents and efforts of Glenn Mallory and Juan Hajdu, a comprehensive text, entitled Electroless Plating: Fundamentals and Applications, is available through AESF Headquarters. The editors have combined the efforts of 27 contributing authors to produce a wide-ranging text that covers both fundamental and applied aspects of the subject. Published by the AESF, the book was first introduced at SUR/FIN ‘91—Toronto.
963 citations
Patent•
23 Sep 1968
TL;DR: HIGH STABILITY, AUTOCATALYTIC ELECTROLESS NICKEL PLATING BATH COMPRISING an AQUEOUS SOLUTION CONTAINing about 0.08-016 MOLE/LITER NICKels IONS, about 019-0.38 MOLE / LITER HYPOPHOSPHITE IONS and ESSENTIALLY about 035-3.14 MOLE or Liter CITRATE IONS as discussed by the authors.
Abstract: HIGH STABILITY, AUTOCATALYTIC ELECTROLESS NICKEL PLATING BATH COMPRISING AN AQUEOUS SOLUTION CONTAINING ABOUT 0.08-016 MOLE/LITER NICKEL IONS, ABOUT 0.19-0.38 MOLE/ LITER HYPOPHOSPHITE IONS, AND ESSENTIALLY ABOUT 0.35-3.68 MOLE/LITER AMMONIUM IONS, ABOUT 0.0.-1.07 MOLE/LITER ACETATE ION AND ABOUT 0.007-0.14 MOLE/LITER CITRATE IONS, THE SOLUTION HAVING A PH IN THE RANGE OF ABOUT 7.0 TO ABOUT 9.5 THE AMMONIUM IONS COMPLEX PALLADOUS IONS INTRODUCED INTO THE PLATING BATH BY "DRAG OUT" FROM THE ACTIVATOR SOLUTION TO FORM A SOLUBLE AMMONIUM-PALLADIUM COMPLEX, WHICH INHIBITS REDUCTION OF PALLADOUS ION TO ZERO VALENT CATALYTIC PALLADIUM BY THE HYPOPHOSPHITE OF THE BATH. BY THE REMOVAL OF POTENTIAL CATALYST SITES FROM THE BATH OR BY RENDERING THE POTENTIAL SITES RELATIVELY CATALYTICALLY INACTIVE, RANDOM DEPOSITION OF THE NICKEL AND PREMATURE LOSS OF THE BATH IS AVOIDED.
154 citations
TL;DR: 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.
119 citations
TL;DR: In this paper, the effect of phosphorus on the corrosion behavior of electroless nickel-plated mild steel in deaerated 40 w/o NaOH solution was examined using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) techniques.
Abstract: Electroless Ni-P deposits with phosphorus content ranging from 4.8 to 12.8 weight percent (w/o) were examined using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) techniques to characterize the effect of phosphorus on the corrosion behavior of electroless nickel-plated mild steel in deaerated 40 w/o NaOH solution. Anodic polarization of the electroless Ni-P alloys in caustic NaOH solution shows that the passive current density decreases with increasing phosphorus content in the deposits. At an applied potential of -1.2 V vs. saturated calomel electrode (V SCE ) (close to their E corr ), EIS data indicate that the R ct for Ni-P alloys in NaOH solution increases with increasing phosphorus content. X-ray photoelectron spectroscopy (XPS) results suggest that the primary constituent formed on the Ni-P surface after EIS measurement in 40 w/o NaOH solution at an applied potential of -0.4 V SCE (in the passive region) is Ni(OH) 2 , which is responsible for the passivity of the Ni-P alloys. The polarization resistance of Ni-P alloys in NaOH solution at -0.4 V SCE also increases with increasing phosphorus content
111 citations