Microstructure and corrosion-wear resistance of laser cladding Al-Ni-TiC-CeO₂ composite coatings

Abstract

Al-Ni-TiC-CeO2 composite coatings were prepared by laser cladding technique on S355 offshore steel.The surface-interface morphologies,chemical element distribution, phase compositions, microhardness of the as-prepared coatings were analyzed by means of scanning electron microscope (SEM),energy dispersive X-ray spectrometer (EDS),X-ray diffractometer (XRD) and microhardness tester. Also, the corrosive wear resistance and stress corrosion cracking (SCC) of the coatings in 3.5%(mass fraction)NaCl solution were studied. The results show that the coating is mainly composed of TiC and AlNi3 phases as well as AlFe3 phase. The surface of the coating is relatively smooth, there is no obvious crack, and the dilution rate is 5%. The surface hardness of the coating is 809.3HV0.2, which is 2.3 times as high as the substrate. The interaction is mainly corrosion accelerating abrasion in the substrate, while it is wear accelerating corrosion in the coating. The SCC susceptibility of the substrate and coating are 35.01% and 17.69% respectively, which indicates that the coating can inhibit the SCC obviously.

Keywords

• laser cladding
• corrosive wear
• stress corrosion cracking
• composite coating
• s355 offshore steel