TITLE:
Study of Potentiodynamic Polarization Behaviour of Electroless Ni-B Coatings and Optimization using Taguchi Method and Grey Relational Analysis
AUTHORS:
Suman Kalyan Das, Prasanta Sahoo
KEYWORDS:
Electroless coatings, Ni-B, Corrosion, Grey Taguchi.
JOURNAL NAME:
Journal of Minerals and Materials Characterization and Engineering,
Vol.10 No.14,
November
25,
2011
ABSTRACT: Electroless nickel coatings are very popular for their corrosion resistant actions. The present
article attempts to study the corrosion behaviour of electroless Ni-B coatings by varying the
coating parameters viz. bath temperature, reducing agent concentration and nickel source
concentration together with the annealing temperature. The electrochemical parameters viz.,
corrosion potential and corrosion current density are evaluated with the help of
potentiodynamic polarization experimentation. Taguchi based Grey analysis is employed in
order to optimize this multiple response problem and the optimal combination of parameters
for maximum corrosion resistance for Ni-B coatings is presented. Moreover, analysis of
variance reveals that bath temperature and concentration of nickel source have significant
influence on the corrosion performance of the coating. The microstructure characterization
of the coating is also conducted with the help of scanning electron microscopy, energy
dispersive X-ray analysis and X-ray diffraction analysis. The Ni-B coating in general exhibits
a nodular structure and turns crystalline with heat treatment. The corroded surface exhibits
cracks and black spots which imply the occurrence of localized corrosion.