Impedance spectroscopy studies of electroless Ni-P matrix, Ni-W-P, Ni-P-ZrO 2 , and Ni-W-P-ZrO 2 coatings exposed to 3.5% NaCl solution : Impedance spectroscopy studies

Stankiewicz, A; Masalski, J; Szczygie?, B

Abstract

Ni–P matrix, ternary Ni–W–P and Ni–P–ZrO2 coatings, and quaternary Ni–W–P–ZrO2 coatings were deposited using electroless method from a glycine bath. Their corrosion resistance was evaluated by electrochemical impedance spectroscopy (EIS) for various immersion times in a 3.5% NaCl solution. From among the investigated coatings, the ternary Ni–W–P coatings show the highest resistance to corrosion in the first hour of exposure to the 3.5% NaCl medium. An addition of ZrO2 adversely affects the performance of both the Ni–P coatings and the Ni–W–P coatings. For all the coatings, including the ones containing tungsten, a marked decrease in pore resistance (Rpor) over time is observed. This means that their corrosion resistance and capacity to protect the substrate decline. On the other hand, after 24 h immersion in the 3.5% NaCl solution the Ni–W–P coating shows the highest low-frequency impedance modulus (|Z|f = 0.01 Hz). As regards corrosion resistance, the Ni–P coatings and the Ni–W–P coatings perform best.

• Journal Article Type: Article
• Acceptance Date: Oct 31, 2012
• Online Publication Date: Nov 5, 2012
• Publication Date: 2013-10
• Deposit Date: Oct 17, 2016
• Journal: Materials and Corrosion
• Electronic ISSN: 0947-5117
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 64
• Issue: 10
• Pages: 908-913
• DOI: https://doi.org/10.1002/maco.201206856
• Keywords: composite coating; corrosion resistance; EIS; electroless plating; Ni–P
• Public URL: http://researchrepository.napier.ac.uk/Output/311541