Physicochemical Principles of Nickel Plating

Gorbunova, K.M.; Никифорова, А. А.; Myers, H. S.

doi:10.1149/1.2425659

Cited by 14 publications

(11 citation statements)

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“…Figure 4 illustrates that an increase in [H + ] of 104 decreases the decomposition rate by a factor of 4. This small effect of pH on the decomposition rate suggests that it stems from changes in the electrochemical potential of the catalyst (7,25) imposed by the half-cell reaction 1/2 H2~H +1 + e -1…”

Section: Resultsmentioning

confidence: 99%

“…Similarities between the behavior of the standard hydrogen electrode 'and that of Ni electrodes immersed in hot H2PO2 -1 solutions suggested that Ni electrodes are saturated with hydrogen (7). At room temperature and neutral pH, the rate of isotope exchange between H2PO2 -1 (D2PO2 -1) or HPO3 -~ (DPO3 -2) and D20(H20) is negligible (8)(9)(10)(11)(12), but at room temperature and pH ~ 2 the rate of exchange for I'-I2PO2 -1 is comparable to the rate of decomposition cor~ducted at 100 ~ and neutral pH (13,14).…”

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confidence: 89%

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The Nickel Metal Catalyzed Decomposition of Aqueous Hypophosphite Solutions

Marshall¹

1983

J. Electrochem. Soc.

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Hot aqueous hypophosphite (H2PO~ ') solutions are exhaustively decomposed to orthophosphite (HPO~2) in the presence of etched Ni wire according to the rate law d[H2PO~']/dt = -ko [H~PO~ ~] x (catalyst area). The activation energy is about 2.6 kcal/mol and the rate increases 4-fold with pH in the range 3 -< pH -< 7. Ni catalyzes the isotopic exchange between H~PO~ -~ and D20 as well as the decomposition. When [HPO~ -2] -> 0.15~/at the start of reaction, the catalyst is completely passivated with respect to the decomposition but not with respect to the isotopic exchange. The H2:HD:D2 volume ratio of the evolved gas is about 5:6:7. A mechanism for the decomposition is discussed and related to "electroless" plating.In spite of numerous investigations into the chemistry of "electroless" plating (1), experimental results relevant to the primal catalyzed hypophosphite decomposition Ni H2PO~ -1 + H20--> HPO3 -'2 ~ H2~ + H +1[1] A are few. Although H2PO~. -1 is distinguished by a standard redox potential of --0.SOV (2), reactions with most oxidizing agents are very slow, especially at 25 ~ and neural pH. This lack of reactivity is generally ascribed to very small concentrations of a "3-centered" intermediate (3-5) which H2PO2 -1 must rearrange prior to its oxidation.The electrochemical oxidation of H2PO2 -1 is also slow and occurs at appreciable rates only at elevated temperature on Ni and Pd surfaces (6). At room temperature only 02 is-evolved from an Ni anode, and H2PO2 -1 is not electrochemically oxidized on Pt even at elevated temperature.Similarities between the behavior of the standard hydrogen electrode 'and that of Ni electrodes immersed in hot H2PO2 -1 solutions suggested that Ni electrodes are saturated with hydrogen (7). At room temperature and neutral pH, the rate of isotope exchange between H2PO2 -1 (D2PO2 -1) or HPO3 -~ (DPO3 -2) and D20(H20) is negligible (8-12), but at room temperature and pH ~ 2 the rate of exchange for I'-I2PO2 -1 is comparable to the rate of decomposition cor~ducted at 100 ~ and neutral pH (13,14).Reaction [1] is negligible in the absence of catalyst at 100 ~ and does not take place without H20 (15). The .decomposition rate at 100 ~ is 1.2 mM/hr 9 cm 2 for [H2PO2-1] --0.25M (Fig. 2). In the presence of 3 mM Ni +2, but under otherwise comparable conditions, H2PO2 -1 is consumed at 3.2 mM/hr 9 cm 2 (16). During "electroless" plating ([Ni +2] -= 0.1M) H2PO2 -1 is consumed at 5 mM/hr 9 cm 2 (15).When H2PO2 -1 and D20 or D2PO2 -1 and H20 are decomposed at pH's between 3 and 5 over finely divided Ni, approximately equal amounts of the hydrogen isotopes are present in the evolved gas (17)(18)(19). During Ni plating the gas is heavily enriched in the hypophosphite isotope while this isotope is not detected in the water (17,20,21).Difficulties in preparing a reproducible Ni surface exhibiting a sustainable and useful level of activity have been a major hindrance to obtaining definitive mechanistic data. This problem was noted in Ref. (16 and 22). Catalyst sensitivity may be more noticeable under...

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Section: Resultsmentioning

confidence: 99%

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confidence: 89%

The Nickel Metal Catalyzed Decomposition of Aqueous Hypophosphite Solutions

Marshall¹

1983

J. Electrochem. Soc.

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“…For example, phosphorus codeposited with nickel will increase the hardness of the coating, but also reduce the melting point and the conductivity. The detailed theory of electroless plating has been discussed in a number of works (23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33).…”

Section: Theory Of Electroless Platingmentioning

confidence: 99%

Electroless Deposition

Durkin

2016

Kirk-Othmer Encyclopedia of Chemical Technology

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Over the past 15 years, several legislative regulations have been implemented that have impacted the evolution of electroless technology and the chemistry platforms utilized across many industries. In year 2000, as a result of the implementation of End of Life Vehicle (ELV) 2000/53/EC Annex II and Restriction of Hazardous Substances (RoHS) 2002/95/EC regulatory introductions, specifically the electroless nickel-phosphorus technology (ENP) that had existed since the 1960s, required redevelopment to meet these demands if these coatings were to remain a viable option in the marketplace.Specific for electroless chemistry systems, these regulatory initiatives impacted the utilization of lead stabilizers and cadmium brighteners by restricting their use. Since this time, the surface finishing industry suppliers of these technologies entered a phase of reinvention for their replacement. To date, this technology rework has afforded many of the chemical suppliers and the industry educators, who focused on this chemistry, an opportunity to improve the technology through rejuvenated research and development (R&D) programs and investment for the technology. During this redevelopment period, technology suppliers providing electroless systems have been able to demonstrate many advances in replacing the original 60-year-old technology platforms where lead and cadmium were utilized as primary stabilizers and brightener species for meeting various applications in the automotive, aerospace, electronics, and industrial sectors. As a result of new investment and the success of R&D programs, this author believes the industry has reached a new platform of electroless technology development and the performance of these newer systems has surpassed ENP developed prior to 2009. Over the past several years, the technology has evolved to a fifth generation phase of development and will continue to move forward with release of improved performance systems (1). This evolution of the technology can be summarized in the following EN revolutionary historical perspective: $1955-1960 Kanigen: 7-10% P, difficult to operate, general-purpose EN, no longer a laboratory curiosity.

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“…It is usually impractical to use very low pH solutions because the deposition rates are low in such solutions [29,30]. The deposition rate of alkaline electroless nickel baths relatively unaffected by bath pH within the normal range employed [31].…”

Section: Effect Of Phmentioning

confidence: 99%

Electroless deposition of ternary Ni–P alloy coatings containing tungsten or nano-scattered alumina composite on steel

Hamdy

Shoeib

Hady³

et al. 2007

J Appl Electrochem

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The performance of ternary electroless deposited Ni-P-W and Ni-P-alumina composite coatings on low carbon steel substrates was studied. The effect of experimental parameters, such as temperature, pH, nickel sulfate concentration, sodium hypophosphite concentration, sodium citrate concentration, and deposition time on the deposition rate were investigated. The coating brightness, coherence, and uniform surface distribution were improved due to addition of W and alumina. The coating performance was evaluated based on the wear-resistance, micro-hardness, and corrosion resistance. The Ni-P-W ternary alloy coatings showed the highest micro hardness, wear-resistance, brightness, and corrosion resistance. The improvement in the performance of Ni-P-W coatings can be explained by the formation of a tungsten phosphide phase.

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Physicochemical Principles of Nickel Plating

Cited by 14 publications

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The Nickel Metal Catalyzed Decomposition of Aqueous Hypophosphite Solutions

The Nickel Metal Catalyzed Decomposition of Aqueous Hypophosphite Solutions

Electroless Deposition

Electroless deposition of ternary Ni–P alloy coatings containing tungsten or nano-scattered alumina composite on steel

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