Ni-Co-ZrO₂ nano-composites are electrodeposited from sulphamate electrolyte and a comparison is made with Ni-ZrO₂ in terms of structure and properties. The Co content in the coatings is in the range of 10-80wt%. The deposition conditions like current density, pH are optimized in terms of microhardness and amounts of ZrO₂ incorporated. The microhardness studies revealed that the maximum hardness is exhibited by Ni-28Co-2ZrO₂ composite. The FESEM study showed a change in morphology from polyhedral to ridge with increase in Co content from 10 to 80wt%. A change in crystal structure from fcc to hcp is also seen. The effect of annealing treatment in terms of microhardness is studied by subjecting the composite electroforms to 800â. The Co rich composite exhibited better stability compared to Ni rich composites. Ni-28Co-2ZrO₂ composite exhibited better immersion corrosion resistance while, Ni-ZrO₂ composite displayed better electrochemical corrosion resistance. The wear studies showed that Ni-10Co-2ZrO₂, Ni-28Co-2ZrO₂ composites showed better resistance. Thus, it is seen that the coatings can be tailored to suit various applications.
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Srivastava et al. (2012) studied this question.