Rare earth has been widely used in materials manufacturing to improve hardness and toughness. In this paper, conventional, nanostructured and CeO 2 modified WC-12Co powders were sprayed by using HVOF spraying technology. Erosion-corrosion behavior and interaction role of erosion and corrosion of the three coatings in 3.5wt% NaCl solution were investigated. In situ observation method was employed to analyze failure mechanism. The results showed that CeO 2 modified WC-12Co coatings possessed the best erosion-corrosion resistance, which is the worst for the conventional WC-12Co coating. The addition of rare earth CeO 2 into conventional WC-12Co coating can improve the erosion-corrosion behavior. Results suggested that the erosion-corrosion mechanism in the three coatings was dominated by corrosion-enhanced erosion. However, the extent of corrosion enhanced erosion was different.

In this study, cored wires and high velocity arc spraying technique (HVAS) were applied to produce Zn-Al and Zn-Al-Mg alloy coatings on low carbon steel substrates. The microstructures and mechanical properties were studied by SEM, EDS, XRD, and Vickers micro-indentor. The electrochemical corrosion behaviors of Zn-Al and Zn- Al-Mg coatings were investigated comparing with Zn and Al coatings in 5%NaCl. The results show that, Zn-Al and Zn-Al-Mg coatings have good quality of uniform microstructure and low porosity. The corrosion resistance of Al coating deteriorated rapidly after nearly 16h immersion, and then kept at a relative stable value. In the contrast, the corrosion potential of the coatings containing Zn decreased a little and then increased towards the noble potential. The potentiodynamic polarization tests show that the icorr value of Zn-Al coating changed greatly at different steps, and it trended to increase continuously which may imply that the coating is easy to be corroded. Comparatively, no obvious change had been found in the Zn-Al-Mg coating which may indicate that the corrosion resistance enhanced with the addition of Mg, and the role of Mg appears to be associated with the self sealing process. Abstract only; no full-text paper available.