EFFECT OF NANO RARE EARTH ON CORROSION RESISTANCE OF THERMAL SPRAYED WC/12Co COATING

Rare earth has been widely used in materials manufacturing to improve mechanical properties. In this paper, Nano-CeO 2 -modified WC/12Co coating with biomodal-sized WC was produced by using high speed oxygen flaming (HVOF) spraying technology. XRD phase analysis showed that the decarburization of WC in coating doped with nano-CeO 2 was slighter than no-doped coating. Potentiodynamic polarization showed that the nano rare earth modifier had improved the corrosion resistance of WC/12Co coating. In addition, long-term immersion in 3.5[Formula: see text]wt.% NaCl solution was conducted and the surface morphologies after immersed 200[Formula: see text]h were observed to investigate the corrosion mechanisms. The results showed WC-12Co coatings with 2[Formula: see text]wt.% nano-CeO 2 possessed better corrosion resistance and the one without nano rare earth was corroded seriously. The positive effect of CeO2 on corrosion resistance of WC/12Co coating can be attributed to the improvement of interfacial strength between Co binder phase and WC particles.