Corrosion behaviour of pulse electrodeposited Nickel based composite coatings

Veenashree, M and Prasad, G and Chakradhar, RPS and Srivastava, Meenu (2014) Corrosion behaviour of pulse electrodeposited Nickel based composite coatings. In: CORCON 2014, 12 Nov 2014, Mumbai, Maharashtra, India.

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Ni-SiC composite is widely adopted as a functional coating in aerospace and automobile applications. However, the limitation with this coating is that at temperatures above 400oC nickel reacts with silicon carbide to form brittle silicides which deteriorates the performance of the coating. Oxides are thermally more stable than carbides and hence, in the present study an attempt has been made to compare the corrosion behaviour of pulse electrodeposited Ni-ZrO2 and Ni-YSZ coatings with Ni-SiC coatings in 3.5%NaCl medium. The three composite coatings were deposited under identical conditions i.e.10% duty cycle and average current densities in the range of 400-700mA/inch2. The microhardness of Ni-YSZ coating was higher than that of Ni-ZrO2 and Ni-SiC coatings. The corrosion behaviour of the coatings was evaluated using polarization and electrochemical impedance studies in 3.5wt%NaCl medium. The Ni-YSZ coating displayed better corrosion resistance due to low corrosion current density (icorr) and high polarization resistance (Rp) compared to Ni-ZrO2 and Ni-SiC composite coatings. The icorr values at constant average current density of 400mA/inch2 are 0.1µA/cm2, 3.9 µA/cm2 and 14.6 µA/cm2 for Ni-YSZ, Ni-ZrO2 and Ni-SiC coatings respectively.An increase in icorr was observed with increase in current density from 400-700mA/Inch².The charge transfer resistance (Rct) was the highest for Ni-YSZ coating affirming the above behaviour.

Item Type: Conference or Workshop Item (Paper)
Subjects: CHEMISTRY AND MATERIALS > Composite Materials
Depositing User: Mrs SK Pratibha
Date Deposited: 25 Jun 2015 10:50
Last Modified: 25 Jun 2015 10:50

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