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Electrodeposition of Nickel and Nickel Alloy Coatings with Layered Silicates for Enhanced Corrosion Resistance and Mechanical Properties

The new nickel/layered silicate nanocomposites were electrodeposited from different pHs to study the influence on the metal ions/layered silicate plating solution and on the properties of the deposited films. Nickel/layered silicate nanocomposites were fabricated from citrate bath atacidic pHs (1.6−3.0), from Watts’ type solution (pH ~4-5), and from citrate bath at basic pH (~9). Additionally, the new nickel/molybdenum/layered silicate nanocomposites were electrodeposited from citrate bath at pH 9.5. The silicate, montmorillonite (MMT), was exfoliated by stirring in aqueous solution over 24 hours. The plating solutions were analyzed for zeta potential, particle size, viscosity, and conductivity to investigate the effects of the composition at various pHs. The preferred crystalline orientation and the crystalline size of nickel, nickel/layered silicate, nickel/molybdenum, and nickel/molybdenum/layered silicate films were examined by X-ray diffraction. The microstructure of the coatings and the surface roughness was investigated by scanning electron microscopy and atomic force microscopy. Nickel/molybdenum/layered silicate nanocomposites containing low content of layered silicate (1.0 g/L) had increase 32 % hardness and 22 % Young’s modulus values over the pure nickel/molybdenum alloy films. The potentiodynamic polarization and electrochemical impedance measurements showed that the nickel/molybdenum/layered silicate nanocomposite layers have higher corrosion resistance in 3.5% NaCl compared to the pure alloy films. The corrosion current density of the nickel/molybdenum/layered silicate nanocomposite composed of 0.5 g/L MMT is 0.63 µA·cm-2 as compare to a nickel/molybdenum alloy which is 2.00 µA·cm-2.

Identiferoai:union.ndltd.org:unt.edu/info:ark/67531/metadc699999
Date08 1900
CreatorsTientong, Jeerapan
ContributorsGolden, Teresa Diane, 1963-, D'Souza, Nandika Anne, 1967-, Mohamed, Adel M. A., Chyan, Oliver Ming-Ren, Marshall, Paul, 1960-
PublisherUniversity of North Texas
Source SetsUniversity of North Texas
LanguageEnglish
Detected LanguageEnglish
TypeThesis or Dissertation
Formatxiii, 173 pages : illustrations (some color), Text
RightsPublic, Tientong, Jeerapan, Copyright, Copyright is held by the author, unless otherwise noted. All rights reserved.

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