In this study, Ni–P, Ni–W–P and Ni–B coatings were electrolessly plated on aluminium alloy substrates. All coatings were uniform and adherent with shiny metallic appearances. A systematic study was performed to evaluate the coating mechanical properties including hardness and wear resistance. The Ni–B coating possessed a superior mechanical performance, showing the highest hardness and wear resistance among the examined coatings. Besides, a further study regarding the wear behaviour confirmed a different wear mechanism of Ni–B coating when compared to the Ni–P and Ni–W–P coatings under the wear tests, which is revealed by the 3D profile images of wear tracks.

Superhydrophobic surfaces – driven from natural biology – are being increasingly studied in many engineering fields. This study fabricated hydrophobic AAO/Ni coatings and superhydrophobic AAO/Ni/Ni coatings based on aluminium alloy substrates. The surface morphologies of prepared samples were systematically examined, and the compositional analysis was conducted. Furthermore, the corrosion resistance of the superhydrophobic coatings was determined by electrochemical measurement. The AAO/Ni coatings revealed a micro-sized, lotus-like surface, showing hydrophobicity with a static water contact angle ranging from 133° to 148°. In contrast, the AAO/Ni/Ni samples possessed superhydrophobicity with a static water contact angle reaching 158° in this case. The corrosion results indicated the superior corrosion resistance of AAO/Ni/Ni, owing to both the surface roughness and surface organic modification. A detailed preparation pathway was proposed for the electrodeposition process of AAO/Ni/Ni. Among the tested samples, the AAO/Ni/Ni sample with the appropriate nickel electrodeposition duration showed the best superhydrophobicity and corrosion resistance.

Sn-Co binary alloy coatings are widely used as substitutes for chromium coatings in many aspects of modern industry. In this research, TiO2 nanoparticles were incorporated into the matrix of Sn-Co coatings aiming to enhance coating performance. The microstructure, mechanical properties and corrosion resistance of Sn-Co-TiO2 coatings were investigated systematically. The results found that the content of TiO2 nanoparticles imposed significant effects on the microstructure and properties of Sn-Co TiO2 coatings. Comparing with Sn-Co film, Sn-Co-1 g/L TiO2 coating has an increased microhardness of ~409 HV. Also, the corresponding wear resistance and corrosion behavior of coatings were enhanced as well. The strengthening mechanism could be attributed to the structural evolution of coatings along with the addition of TiO2 nanoparticles. The relationships among TiO2 nanoparticles concentration, microstructure and properties were discussed in detail.