Synthesis and characterization of Ni–Al2O3 composite coatings containing different forms of alumina

Aruna, ST and William Grips, VK and Rajam, KS (2010) Synthesis and characterization of Ni–Al2O3 composite coatings containing different forms of alumina. Journal of Applied Electrochemistry, 40. pp. 2161-2169. ISSN 1572-8838

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Abstract

Electrodeposited Ni–Al2O3 composite coatings were prepared using alumina powders synthesized from solution combustion method, precipitation method and a commercial source. Solution combustion synthesized alumina powder yielded a-phase; precipitation method yielded purely c-phase; commercial alumina powder was a mixture of a-, d- and c-phases. A nickel sulfamate bath was used for electro-codeposition. The current densities (0.23 A dm-2 for 20 h, 0.77 A dm-2 for 6 h, 1.55 A dm-2 for 3 h and 3.1 A dm-2 for 1.5 h) and bath agitation speeds (100, 200, 600 and 1000 rpm) were varied. The pH variations of the bath were higher during the electrodeposition of combustion synthesized lumina. The effect of different forms of alumina particles on the microhardness and microstructure of the nickel composite coating was studied. Composite coating containing combustion synthesized alumina particles was found to have higher microhardness (550 HK). It was found that at lower agitation speed (100 rpm), bigger particles were incorporated and at higher agitation speed (1000 rpm), smaller particles were incorporated. The area fraction of alumina particles incorporated in nickel matrix was highest for commercial alumina (24%). This study shows that it is not suffice to take just the current density and stirring speeds into account to explain the properties of the coatings but also to take into account the source of particles and their properties.

Item Type:	Article
Uncontrolled Keywords:	Ni Electrodeposition Microhardness XRD Alumin
Subjects:	CHEMISTRY AND MATERIALS > Chemistry and Materials (General) CHEMISTRY AND MATERIALS > Inorganic, Organic and Physical Chemistry
Depositing User:	Dr Aruna /ST S.T. Aruna
Date Deposited:	01 Jun 2011 11:07
Last Modified:	01 Jun 2011 11:07
URI:	http://nal-ir.nal.res.in/id/eprint/9190

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