Studies on autocatalytic deposition of ternary Nix2013;Wx2013;P alloys using nickel sulphamate bath

Balaraju, JN and Jahan, SM and Rajam, KS (2006) Studies on autocatalytic deposition of ternary Nix2013;Wx2013;P alloys using nickel sulphamate bath. Surface and Coatings Technology, 201 (3-4). pp. 507-512.

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Abstract

An attempt has been made to deposit ternary Nix2013;Wx2013;P coatings autocatalytically using nickel sulphamate and sodium tungstate as nickel and tungsten sources, respectively, and sodium hypophosphite as a reducing agent. These coatings were deposited using an alkaline citrate based bath and were compared with plain Nix2013;P coatings. Both deposits were characterized for their structure, morphology, crystallization behavior and microhardness. Results obtained from EDX analysis showed that binary Nix2013;P alloy contains 11.0 wt.% of phosphorus. Incorporation of tungsten (2.7 wt.%) had reduced the phosphorus content to about 3.5 wt.% in ternary Nix2013;Wx2013;P deposits. Apart from phosphorus and nickel contents, a trace of sulphur was noticed in ternary Nix2013;Wx2013;P deposit. Structural examination carried out by XRD studies revealed the presence of a broad peak with a calculated grain size of 1.2 nm for binary alloy, where as a sharp peak with a grain size of 10 nm is obtained for ternary Nix2013;Wx2013;P alloy. Optical micrographs of as-plated binary Nix2013;P alloys exhibited slightly nodular structure compared to coarse nodular structure of ternary Nix2013;Wx2013;P deposits. Etched metallographic cross-sections revealed a lamellar/banded structure in both deposits. Studies on phase transformation behavior carried out by DSC showed that the crystallization temperature for ternary alloys was higher compared to binary alloys. Calculated activation energies for Nix2013;P and Nix2013;Wx2013;P deposits were 229 and 289 kJ/mol, respectively. Microhardness measurements made on as-plated and heat-treated (400 xB0;C for 1 h) deposits showed higher hardness values for ternary Nix2013;Wx2013;P deposits compared to binary deposits.

Item Type: Journal Article
Uncontrolled Keywords: Nickel sulphamate;Sodium tungstate;Binary alloys
Subjects: AERONAUTICS > Aeronautics (General)
CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
Division/Department: Surface Engineering Division, Surface Engineering Division, Surface Engineering Division
Depositing User: Ms. Alphones Mary
Date Deposited: 06 Oct 2009
Last Modified: 24 May 2010 09:56
URI: http://nal-ir.nal.res.in/id/eprint/5183

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