Investigation on microstructure and properties of electrodeposited Ni-Ti-CeO2 composite coating

Highlights: • Fixed ratio of Ti and CeO₂ particles were incorporated into Ni coatings. • The addition of particles led to grain refinement and random-orientated growth. • Incorporated Ti particles promoted the formation of pores and surface asperities. • CeO₂ nanoparticles promoted the formation of high-quality composite coating. • Enhanced hardness and wear property were achieved by changing particle contents. Ternary Ni-Ti-CeO₂ composite coatings were synthesized from Watts bath containing various concentrations of mixed particles including Ti microparticles and CeO₂ nanoparticles (fixed ration 10: 1 by weight) by electrodeposition. Microstructures of the composite coatings were comprehensively investigated by XRD, SEM, AFM and TEM. The incorporation of mixed particles gave birth to grain refinement, attenuation of soft mode [200] texture and random-orientated grain growth of nickel deposits. Typically, as for the composite coating electrodeposited form Watts bath containing relatively low concentrations (less than 22 g/L) of mixed particles, the presence of pores inside the coatings, asperities on the surface and cluster-like distribution of Ti microparticles in composite coating, restricted the improvement of properties. By increasing concentration of mixed particles to 88 g/L, high-quality Ni-Ti-CeO₂ composite coating with uniformly distributed Ti microparticles was achieved. The incorporation of Ti microparticles should take great responsibility for the presence of pores and asperities, while the incorporation CeO₂ nanoparticles played very important role in the formation of dense and smooth composite coatings. Microhardness and wear resistance were also improved by increasing contents of mixed particles in composite coatings. The incorporation of mixed particles leaded to increasement of friction coefficient and the friction coefficient presented increasing tendency by increasing the concentrations of mixed particles in Watts bath.