Coatings by arc spraying of nanocrystalline metallic wires on carbon steel surfaces: surface hardness, hydrophobicity, and residual stress

Wire arc spraying of two different metallic wires composed of nanocrystalline and amorphous phases onto carbon steel sheets is carried out. Coating characteristics, including morphological and metallurgical changes, microhardness, residual stress, and surface hydrophobicity are examined using analytical tools. It is found that microhardness increases in the surface region of the coating because of oxidation and high cooling rates. Nanoparticles in the coating act like grain arresting centres contributing to higher residual stress levels. The surface texture of the coating, composed of micro/nanopores, enhances surface hydrophobicity. The coating produced by the 140MXC wire has higher surface hardness than that of the 95MXC wire, resulting in a correspondingly lower friction in the 140MXC wire. However, the residual stress formed in the coating is higher for 140MXC wire than that corresponding to 95MXC wire. In addition, both coatings produced by two different wire sprayings have similar hydrophobic characteristics at the surface.