Enhanced wear resistance of cast ductile iron by Ni-SiC composite coating

Unalloyed ductile iron (DI) has low resistance to wear. Its wear resistance can be enhanced by (i) hardening by heat treatment or (ii) deposition of a hard coating. The electrodeposition of Ni-SiC composite on unalloyed DI (GGG 40) has been investigated. The effect of operating conditions of the electrodeposition process using an acidic bath on the incorporation of Sic in the deposit was studied. Parameters studied included current density, inactivation and activation with PdCl2, and particle content. It was found that the volume per cent of Sic particles incorporated into the composite layer increased with increasing current density and with Sic concentration in the bath. The optimum sic incorporation could be obtained using a bath with 60 g L-1 of Sic particles in suspension at 2 5 A dm(-2), pH 4 and 50 degrees C. The properties of the composite such as hardness and wear resistance were found to be significantly improved compared to the uncoated substrate. It appears economic to increase the wear resistance of as cast DI by application of the Ni-Sic composite by electrodeposition rather than using heat treatments or the addition of expensive alloying elements.