MICROSTRUCTURES AND SALT SPRAY CORROSION BEHAVIORS OF COLD SPRAYED Al COATINGS ON S355 STEEL IN MARINE ENVIRONMENT

An Al coating was sprayed on S355 steel using a cold spraying. The surface–interface morphologies, chemical compositions, and phases of the obtained Al coating were analyzed using a field emission scanning electronic microscope (FESEM), energy dispersive spectrometer (EDS), and X-ray diffractometer (XRD), respectively, and the chemical element distributions of Al coating surface and interface were also analyzed using a plane scan, and line scan, respectively. The salt spray corrosion (SSC) of cold sprayed Al coating was investigated using a neutral salt spray (NSS) test, the corrosion products on the Al coating were also analyzed using an EDS and XRD. The result shows that the cold sprayed Al coating is composed of Al phase, the Al particles are distorted when colliding with the substrate, the interface bonding mode is a mechanical bonding. The cold sprayed Al coating is covered with a stable corrosion products, which effectively prevents the coating from further SSC, showing an excellent corrosion resistance. The Al coating has appropriate cathodal protection potential, the corrosion rate of Al coating declines with the time in the electrochemical test.