Electrochemical studies on electroless ternary and quaternary Nix20P based alloys

Balaraju, JN and Ezhil Selvi, V and William Grips, VK and Rajan, KS (2006) Electrochemical studies on electroless ternary and quaternary Nix20P based alloys. Electrochimica Acta, 52 (3). pp. 1064-1074. ISSN 0013-4686

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Abstract

The autocatalytic (electroless) deposition of Nix2013;P based alloys is a well-known commercial process that has found numerous applications because of their excellent anticorrosive, wear, magnetic, solderable properties, etc. It is a barrier coating, protecting the substrate by sealing it off from the corrosive environments, rather than by sacrificial action. The corrosion resistance varies with the phosphorus content of the deposit: relatively high for a high-phosphorus electroless nickel deposit but low for a low-phosphorus electroless nickel deposit. In the present investigation ternary Nix2013;Wx2013;P alloy films were prepared using alkaline citrate-based bath. Quaternary Nix2013;Wx2013;Cux2013;P films were deposited by the addition of 3mM copper ions in ternary Nix2013;Wx2013;P bath. X-ray diffraction (XRD) studies indicated that all the deposits were nanocrystalline, i.e. 1.2, 2.1 and13; 6.0 nm, respectively, for binary, ternary and quaternary alloys. Corrosion resistance of the films was evaluated in 3.5% sodium chloride solution in non-deaerated and deaerated conditions by potentiodynamic polarization and electrochemical impedance (EIS) methods. Lower corrosion current density values were obtained for the coatings tested in deaerated condition. EIS studies showed that higher charge transfer resistance values were obtained for binary Nix2013;P coatings compared to ternary or quaternary coatings. For all the coatings a gradual increase in the anodic current density had been observed beyond 740mV. In deaerated condition all the reported coatings exhibited a narrow passive region and all the values of Ep, Etp and ipass were very close showing no major changes in the electrochemical behavior. In the non-deaerated conditions no passivation behavior had been observed for all these coatings.13; xA9; 2006 Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Additional Information:	Copyright for this article belongs to Elsevier Ltd.
Uncontrolled Keywords:	Electroless Nix2013;P;Nix2013;Wx2013;P;Nix2013;Wx2013;Cux2013;P;Corrosion;EIS
Subjects:	CHEMISTRY AND MATERIALS > Metals and Metallic Materials CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
Division/Department:	Surface Engineering Division, Surface Engineering Division, Surface Engineering Division, Surface Engineering Division
Depositing User:	M/S ICAST NAL
Date Deposited:	01 Feb 2007
Last Modified:	07 May 2012 11:00
URI:	http://nal-ir.nal.res.in/id/eprint/3983

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