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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26 Oct 2017
TL;DR: The results showed that low frequency ultrasonic agitation could be used to produce coatings from an alkaline NiB bath and that the thickness of coatings obtained could be increased by over 50% compared to those produced using mechanical agitation.
Abstract: &NA; The effect of ultrasound on the properties of Nickel‐Boron (NiB) coatings was investigated. NiB coatings were fabricated by electroless deposition using either ultrasonic or mechanical agitation. The deposition of Ni occurred in an aqueous bath containing a reducible metal salt (nickel chloride), reducing agent (sodium borohydride), complexing agent (ethylenediamine) and stabilizer (lead tungstate). Due to the instability of the borohydride in acidic, neutral and slightly alkaline media, pH was controlled at pH 12 ± 1 in order to avoid destabilizing the bath. Deposition was performed in three different configurations: one with a classical mechanical agitation at 300 rpm and the other two employing ultrasound at a frequency of either 20 or 35 kHz. The microstructures of the electroless coatings were characterized by a combination of optical Microscopy and Scanning Electron Microscope (SEM). The chemistry of the coatings was determined by ICP‐AES (Inductively Coupled Plasma ‐ Atomic Emission Spectrometry) after dissolution in aqua regia. The mechanical properties of the coatings were established by a combination of roughness measurements, Vickers microhardness and pin‐on‐disk tribology tests. Lastly, the corrosion properties were analysed by potentiodynamic polarization. The results showed that low frequency ultrasonic agitation could be used to produce coatings from an alkaline NiB bath and that the thickness of coatings obtained could be increased by over 50% compared to those produced using mechanical agitation. Although ultrasonic agitation produced a smoother coating and some alteration of the deposit morphology was observed, the mechanical and corrosion properties were very similar to those found when using mechanical agitation. HighlightsUltrasound did not bring significant modification of the hardness or wear behaviour.Ultrasonic agitation generates a significant increase of the plating rate.When ultrasonic agitation was employed the coating thickness increased by over 50%.Ultrasonic agitation generates a smoother and less porous morphology.
8 citations
TL;DR: In this article, the performance of EL Ni-B coated brass contacts under fretting conditions was evaluated and the contact resistance was measured as a function of fretting cycles, and the surface profile and wear depth of the fretted zone were measured using a laser scanning microscope.
Abstract: The performance of electroless (EL) Ni–B coated brass contacts under fretting conditions was evaluated. The contact resistance of EL Ni–B coated brass contact was measured as a function of fretting cycles. The surface profile and wear depth of the fretted zone were measured using laser scanning microscope. The study reveals that EL Ni–B coated contacts exhibit better performance under fretting conditions. However, at conditions which are prone for severe oxidation such as, low frequency (3 Hz) or high temperature (155°C), EL Ni–B coated contacts fail to exhibit a better stability. The quick removal of the oxide film by fretting motion, rapid oxidation of the fresh metallic particles and trapping of the oxidation products in the remaining coating, cause the contact resistance to increase to unacceptable levels at such conditions. The study concludes that EL Ni–B coating is not a suitable choice for connector contacts that could experience fretting under highly oxidizing conditions.
8 citations
TL;DR: In this paper, the authors successfully obtained Ni-B and Ni-Ce coatings with and without sonication on low-carbon steel (Q235) through electroless plating with the deposition time of 60min.
Abstract: We successfully obtained Ni–B and Ni–B–Ce coatings with and without sonication on low-carbon steel (Q235) through electroless plating with the deposition time of 60min. The surface morphology and elemental composition of the coatings were evaluated by scanning electron microscopy (SEM) and inductively coupled plasma (ICP). The 11μm thick sonicated Ni–B–Ce (Son-Ni–B–Ce) coating is uniform with the composition of Ni 87.1%, B 6.2% and Ce 6.6%. X-ray diffraction (XRD) measurements implied a typical broaden peak around 44∘, considered as amorphous structure which was confirmed by selected area electron diffraction pattern (SAED). Atomic force microscopy (AFM) showed a typical circular pit of Ni–B–Ce coating and Son-Ni–B–Ce coating. X-ray photoelectron spectroscopy (XPS) revealed the chemical status of coating components. The mechanical and corrosion resistance properties were determined by Vickers hardness tester, potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy (EIS) in 3.5wt. %...
8 citations
TL;DR: In this article, the authors present a simple way to preselect metallic ions that can act as a stabilizing agent in electroless nickel-boron plating, based on three aspects: the redox potential of the cation, the catalytic activity for hydrogenation and the atomic size of the metal.
Abstract: Electroless nickel‑boron coatings present exceptional wear and corrosion resistance, but the presence of toxic heavy metals like Pb or Tl in most plating baths and the coatings synthesized using them impedes their widespread use. In this study, several candidates potential as stabilizing agent were investigated (Pb2+, Ti3+, V3+, Mn2+, Fe3+, Co2+, Cu2+, Zn2+, Ge4+, Zr4+, Nb5+, Mo5+, Ce3+,Ag1+, In3+, Sn2+, W6+and Bi3+). The investigation was based on the fact that stabilizers can stop the deposition in high concentration, once stabilizers also act as inhibitors depending on the concentrations—four distinct groups where observed. In group 1: Cu2+, Zn2+, Ge4+, Ce3+, Zr4+, In3+, Sn2+ and Bi3+, the solution is not decomposed until the end of deposition time (1 h) a deposition take place. Group 2: Ti3+, Mn2+, Fe3+, Co2+, Nb5+ and W6+ causes bath decomposition in less than 5 min. In Group 3: Mo5+, Ag1+ and V3+ the solution decompose in less than 1 min due to the presence of surface activators. Last, group 4: Pb2+ and Tl1+, are toxic stabilizers already studied in the literature. This paper presents a simple way to preselect metallic ions that can act as a stabilizing agent in electroless nickel‑boron plating. The method includes 3 aspects: The redox potential of the cation, the catalytic activity for hydrogenation and the atomic size of the metal. Besides, two green stabilizers were identified: Bi2(WO4)3 and SnCl2 that act as a stabilizer for concentrations of 10−5 mol/L and 10−3 mol/L respectively.
8 citations
TL;DR: In this paper, the effects of temperature on the friction and wear behavior of Ni-P-B alloy coatings have been investigated, and the results show that Ni-p-B coatings sustain the elevated temperatures with minimal effect on friction performance.
Abstract: Ni–P–B coatings are produced directly on surface of carbon steel (AISI 1040) using electroless plating technique. The effects of temperature on the friction and wear behavior of Ni–P–B alloy coatings have been investigated. Tribological tests are conducted at four temperatures (30, 100, 300 and 500 °C) under constant load and sliding speed in a pin-on-disk apparatus. Results show that Ni–P–B coatings sustain the elevated temperatures with minimal effect on friction and wear performances. Ni–P–B coating is found to exhibit the maximum hardness among the binary Ni–P and Ni–B coatings with as-deposited hardness reaching around 700HV. Heat treatment increases the hardness as well as wear resistance by precipitation of boride and phosphide phases of nickel. Room temperature test shows mostly adhesive wear pattern but finally, it leads to a mixture of abrasive–adhesive wear mechanism. Friction and wear of Ni–P–B is overall governed by the formation of oxidative layer, mechanically mixed layer with iron (from ferrous counter face), wear mechanism, phase transformation and changes in microstructure during elevated wear test. Phase transformation and corresponding micro-structural changes occurring during elevated test duration help in providing better wear resistance to the coating.
7 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