Microstructure and Corrosion Resistance of Arc Sprayed Zn-Al Based Coatings

Pure Al, Zn-Al and Zn-Al-Ni coatings with the same thickness were prepared on the surface of Q235 steel substrate by arc spraying. The microstructure, adhesive strength and corrosion resistance of the three coatings were analyzed and compared. The results show that the three coatings all had good arc spraying forming quality, among which Zn-Al-Ni coating showed a characteristic of multiphase structure with a small amount of fcc-Al phase dispersing in hcp-Zn phase and fcc-Ni(Al) phase. At the same thickness, the introduction of Ni in Zn-Al-Ni coating could significantly improve the bonding strength between the coating and the substrate. The pure Al coating and Zn-Al-Ni coating could improve the corrosion resistance of Q235 steel in 3.5% (mass fraction) NaCl solution and had good salt spray corrosion resistance, compared with those of the Zn-Al coating.