文档介绍：Progress anic Coatings 55 (2006) 355–362
Corrosion resistance of phosphate coatings obtained by cathodic
electrochemical treatment: Role of anode–graphite versus steel
. Sankara Narayanan a,∗, S. Jegannathan b, K. Ravichandran b,1
a National Metallurgical Laboratory, Madras Centre plex, Taramani, Chennai-600113, India
b Department of Applied Chemistry and Chemical Engineering Sri Venkateswara College of Engineering, Sriperumbudur-602105, India
Received 13 July 2005; accepted 19 January 2006
Abstract
The formation of phosphate coatings by cathodic electrochemical treatment using graphite and steel anodes and evaluation of their corrosion
resistance is addressed in this paper. The type of anode used, graphite/steel, has an obvious influence on position of the coating, resulting
in zinc–zinc posite coating with graphite anode and zinc–iron alloy–zinc phosphate–zinc–iron posite coating with
steel anode. The corrosion resistance of the coating is found to be a function of position of the coating. The deposition of zinc/zinc–iron
alloy along with the zinc phosphate/zinc and zinc–iron phosphate using graphite/steel anodes has caused a cathodic shift in the pared
to uncoated mild steel substrates. The icorr values of these coatings is very high. EIS studies reveal that zinc/zinc–iron alloy dissolution is the
predominant reaction during the initial stages of imm