Multifunctional electrodeposited Ni-mullite composite coating

Srivastava, Meenu and Suprita, GK and William Grips, VK (2013) Multifunctional electrodeposited Ni-mullite composite coating. In: National Symposium on Electrochemical Science & Technology (NSEST 2013), 23 Jul 2013, IISc, Bangalore.

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Nickel based composite coatings have attracted a lot of interest particularly for wear resistant and corrosion resistant applications. Among the various composite coatings Ni-SiC is of special interest as it is commercially used as wear resistant coating in rotary and reciprocating engines. However, at temperatures above 450oC SiC reacts with the nickel matrix to form brittle nickel silicide which deteriorates the performance of the Ni-SiC coating. Oxide particle reinforced nickel composite coatings can be an alternate to Ni-SiC coating as the distributed phase- oxides are thermally more stable compared to carbides. In the present study, mullite (3Al2O3.2SiO2) particles have been reinforced in nickel matrix. The advantages of mullite include low thermal conductivity, excellent creep resistance, high-temperature strength, and good chemical stability. The electrodeposition conditions were optimized to obtain maximum particle incorporation. The thermal stability of electrodeposited Ni-mullite coating in terms of microhardness was studied at temperatures upto 800oC and compared with Ni-SiC coating. The hardness value of as plated electroforms was similar for both Ni-mullite and Ni-SiC coating (400Hk). A marginal decrease in the microhardness of Ni-mullite coating occurred at temperatures of 600oC while, significant reduction was observed beyond 400oC for Ni-SiC coating. Thus, the incorporation of mullite particles in nickel matrix improves its thermal stability to a temperature of 600oC. The tribological studies showed that the wear volume loss for Ni-mullite coating is 2.38X10-5mm3/m while, that of Ni-SiC coating is 9.58X10-5mm3/m under identical testing conditions. The corrosion studies using potentiodynamic polarization and electrochemical impedance studies showed that the corrosion resistance of Ni-mullite coating is better than that of Ni-SiC coating. Thus, from the above studies it can be concluded that Ni-mullite has better wear and corrosion resistance compared to Ni-SiC coating in other words it is a multifunctional coating

Item Type: Conference or Workshop Item (Paper)
Subjects: CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
Depositing User: Mr. BS Shivaram
Date Deposited: 28 Oct 2013 05:48
Last Modified: 28 Oct 2013 05:48

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