With Zn and Al mixed powders as raw materials, 65%Zn-Al coatings were prepared by cold gas dynamic spray. The microstructures of the cold-sprayed 65%Zn-Al coatings were characterized by SEM and OM. XRD and EDS were used to analyze the co-deposited characteristics of 65%Zn-Al coatings. The results reveal that a densely co-deposited 65%Zn-Al coating with thickness of about 0.7 mm and porosity of 1.7% is obtained. The deposition efficiency of Al particles on the co-deposited coating is obviously higher than that of Zn particles. The bonding among Zn and Al particles mainly attributes to the plastic deformed mechanical embedding effect, and the combination among particles is tight. Those particles at the interface are broken and fined by continuous collision, so they have relative higher micro hardness than Zn or Al bulk metal. The bonding among the particles in the coating is more strength than the bonding of coating to substrate. There is element diffusion phenomenon in the interface between the coating and the substrate, and no solid solution and compound is observed.

The corrosion behaviors of the cold-sprayed Zn-50Al coatings in seawater were characterized by potentiodynamic polarization and electrochemical impedance spectroscopy(EIS)techniques.The X-ray diffraction(XRD)results of corrosion products and scanning electron microscopy(SEM)analysis of corrosion surface were used to comparatively investigate the corrosion properties of Zn/Al coatings,and to study the selfsealing mechanism.The results indicated that the better corrosion resistance of cold-sprayed Zn-50Al coatings compared with Zn coatings due to the better self-sealing effect which effectively prevents further seawater corrosion.It has more appropriate cathodal protection potential than Al coatings and low corrosion rate than Zn coatings.the corrosion rate of the Zn-50Al coatings retained a low level with time.

The anti-corrosion performance of 30CrMo steel covered with the graphite epoxy composite materials was evaluated in seawater through corrosion potential measurement,galvanic corrosion and neutral salt spray tests.The results show that the graphite epoxy composite materials can effectively prevent seawater corrosion.Intact graphite epoxy composite materials can excellently protect 30CrMo steels from corrosion.But there is an obvious potential difference between the graphite epoxy composite materials and 30CrMo steels.If the surface is not intact,or the surface exhibits some dilapidation,the steel will suffer more serious galvanic corrosion.