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 paper, a preliminary study has been conducted using sequences of isothermal heat treatments and unidirectional high-temperature wear test following ball-on-flat geometry against an alumina counterface, to assess thermal stability and hightemperature tribological properties of the crystalline electroless Ni-B coating.
Abstract: A preliminary study has been conducted using sequences of isothermal heat treatments and unidirectional high-temperature wear test following ball-on-flat geometry against an alumina counterface, to assess thermal stability and high-temperature tribological properties of the crystalline electroless Ni-B coating, a potential candidate for high-temperature solid lubricant coating. Isothermal heat treatment of 450 °C/15 h causes a significant amount of B diffusion into the Fe substrate without altering the coating’s through-thickness hardness and nanostructure. At room temperature, a very low wear rate is observed, which increases up to two orders of magnitude above a testing temperature of 100 °C. Room-temperature wear behavior is mostly governed by oxidative wear, where friction-induced heating produces a thick oxide scale on the wear track, which subsequently decreases the wear rate by preventing direct contact between the coating and counterface. In the case of wear tests above 100 °C, removal of the same oxide layer occurs through local plastic deformation, essentially plastic ratcheting at the contacting region by flow softening of the contacting surface layer due to a local rise in temperature. Worn track morphology shows similarity with the severe wear seen in steel–steel contacts. Experimental observations have been explained and validated using the concept of contact point flash temperature. A quantitative assessment of contact point flash temperature has been carried out adopting the methodology, proposed by Ashby et al. The effects of applied normal load, test geometry, choice of counterface material, and testing temperatures on the transition of wear mechanism are critically discussed.
18 citations
TL;DR: In this paper, a sonicated Ni-B-Ce coating on the surface of low carbon steel (Q235) was obtained through ultrasonic-assisted electroless plating with the deposition time of 60 minutes.
Abstract: We successfully obtained sonicated Ni–B–Ce coating on the surface of low carbon steel (Q235) through ultrasonic-assisted electroless plating with the deposition time of 60 minutes. The coatings wer...
17 citations
Cites background from "Formation and characterization of b..."
...phases in the similar composition range, the major part was amorphous whereas a small part of it was nanocrystalline [30]....
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...[30] discovered that two exothermic peaks of the...
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TL;DR: In this paper, a detailed study of the tribological behavior of the coating is undertaken individually for the three corrosive environments (brine, acidic and alkaline) by varying different coating process parameters as well as varying the testing parameters, viz. applied load and speed.
Abstract: The present paper deals with the study of tribological characteristics, viz. friction and wear, of electroless Ni–P coating in corrosive environments (brine, acidic and alkaline) by varying different coating process parameters as well as varying the tribological testing parameters, viz. applied load and speed. The optimized results of coating process parameters for minimum friction and wear performance of the coating are presented. Moreover, a detailed study of the tribological behavior of the coating is undertaken individually for the three corrosive environments. The results obtained are compared among each other and also with the dry condition test of the coating. It is found that the friction coefficient of Ni–P coating decreases with increase in load for all environments. In case of wear, the wear rate of Ni–P coating gradually increases with increase in load for all mediums but the same decreases after 40N in brine and alkaline mediums. However, for acidic solution, the wear rate shows a continuous increasing trend. It is observed that alkaline and brine environments are favorable from friction and wear point of view of the coating, respectively. Microstructure study of the coatings is also performed and the coating is found to be of cauliflower-like morphology. The coating also exhibits amorphous structure in as-deposited condition, which gradually turns crystalline with heat treatment.
17 citations
TL;DR: In this paper, the effect of incorporation of Si3N4 particles in the ED Ni-B matrix on the surface morphology, structural characteristics and microhardness has been evaluated to correlate the wear resistance.
Abstract: The wear resistance of electrodeposited (ED) Ni–B and Ni–B–Si3N4 composite coatings is compared. The effect of incorporation of Si3N4 particles in the ED Ni–B matrix on the surface morphology, structural characteristics and microhardness has been evaluated to correlate the wear resistance. The wear mechanism of ED Ni–B and Ni–B–Si3N4 composite coatings appears to be similar; both involve intensive plastic deformation of the coating due to the ploughing action of the hard counter disc. However, the extent of wear damage is relatively small for ED Ni–B–Si3N4 composite coatings.
17 citations
TL;DR: Ni-P-SnO2/C composite was prepared by electroless reduction of nickel ions on SnO2 /C powder as discussed by the authors, and the weight percentage of SnO 2 in the prepared composite was varied as 2.5-20.5%.
17 citations
Additional excerpts
...[6] Sankara Narayanan TSN, Seshadri SK....
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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