Microstructure and corrosion behaviour of laser-cladding Al-Ni-TiC-CeO2 composite coatings on S355 offshore steel

Al-Ni-TiC-CeO2 composite coatings were deposited on S355 offshore steels by laser cladding. The microstructure and corrosion behaviour features, such as immersion corrosion and corrosive wear of the as-prepared composite coatings and substrates were investigated. The results showed that an Al-Fe phase and a small amount of amorphous AlFeNi phases were formed on the surface of the coatings. Simultaneously, the coatings showed a good metallurgical bonding with the substrate, the surface of the coating is relatively smooth, there is no obvious crack, and the coating dilution rate was 6.54%, the microstructure of the coating is finer, the reinforcement phase TiC showed a uniform dispersion distribution. The surface hardness of the coating is 855.26 HV0.2, which is 2.35 times as high as the substrate. And the coating can significantly improve the tensile properties of the substrate. The corrosion products formed on the substrate were mainly FeOOH, while those on the coating were Al2O3 and AIOOH. The protective effect of the composite coatings on the substrate increased with increasing immersion time. The substrate exhibited corrosion-accelerating wear, while the coatings exhibited wear-accelerating corrosion. (C) 2018 Elsevier B.V. All rights reserved.