Fabrication of Ni-CeO₂ Nanocomposite Coatings Synthesised via a Modified Sediment Co-Deposition Process

摘要

It is well known that the amount and distribution of co-deposited nanoparticles play important roles inthe properties of the nanocomposite coatings. Therefore improvement of the incorporated nanoparticlecontent in nanocomposite coatings is a crucial factor in the composite electrodeposition process. In thisstudy, a modified sediment co-deposition (SCD) technique was developed to produce Ni-CeO2nanocomposite coatings with a high content of incorporated CeO2 nanoparticles. In this technique, theelectrolyte flows through the gap between the cathode and the anode. Compared with the standardSCD, the modified process is of benefit to large-area electrodeposited coatings because the electrolyteflows through the cathode surface at the same rate, and the bubbles absorbed onto the cathode surfacecan escape from the cathode surface due to shock from the composite electrolyte during the modifiedSCD process. The effects of current density and the CeO2 nanoparticle content in the bath on themorphology, preferred orientation, microhardness, and wear resistance of nanocomposite coatingsobtained from the modified SCD are investigated. The experimental results show that the weight percent of CeO2 particles in the nanocomposite coatings varies with increasing loading of CeO2nanoparticles and current density. The maximum weight per cent of CeO2 particles in the-2 nanocomposite coatings (6.30 wt%) is obtained at a current density of 1 A dm using a concentration-1 of 30 gl of CeO2 particles in the bath, and this maximum is significantly higher than that of coatingsfabricated using the conventional electrodeposition technique. The surface morphology and preferredorientation are altered with the incorporation of CeO2 nanoparticles. A Ni-CeO2 nanocompositecoating with a maximum microhardness of 630 HV is obtained from this process. The NieO2nanocomposite coatings show increased wear resistance compared with that of the pure Ni coating,whereas the composite coating with the highest CeO2 content exhibits the best wear resistance.