The effect of SDS surfactant on tensile properties of electrodeposited Ni-Co/SiC nanocomposites

Ni-Co/SiC nanocomposites were electrodeposited from modified Watts bath containing SiC particles with 50 nm average size. The influence of sodium dodecyl sulphate (SDS) concentration on surface properties of nano-particles, microstructure and mechanical properties of nanocomposites were investigated. The electrodeposition mechanism and particles-cathode interactions were studied by means of cyclic voltammetry (CV) test. The mechanical properties of electrodeposits were investigated by Vickers microhardness and tensile tests. The results indicated that addition of SDS to Ni-Co electrolyte shifted onset of cathodic reactions to higher cathodic potentials and displaced the reduction curve to lower currents at similar potentials due to the adsorption of SDS molecules on cathode surface and suppressing of cathodic reactions. Moreover, addition of SDS to the electrolyte enhanced absolute surface charge and adsorption of metal ions on SiC particles, which in turn, increased the amount and improved the uniform distribution of SiC particles in the deposits. This resulted in considerable enhancement in the microhardness, yield and ultimate tensile strength (UTS) of Ni-Co/SiC deposits. Moreover, addition of SDS up to 0.25 g/L significantly enhanced the elongation to failure of deposits due to impeding the agglomeration of ceramic particles and microstructure refining. Further increase in SDS concentration led to a decrease in ductility due to embrittling of Ni-Co matrix.