Effect of Si on Hot Corrosion Resistance of CoCrAlY Coating

The CoCrAlSiY coating was prepared by HVOF (high velocity oxygen fuel) method. The hot corrosion resistance of the CoCrAlSiY coating with different Si concentrations (0wt%, 2wt% and 5wt%) at 900 °C was discussed by hot salt coating method with a mixed salt of 75wt% Na2SO4+25wt% NaCl. The results show that the average corrosion penetration depth of the coating increases with the rising of temperature, while the increasing of Si concentration decreases the average corrosion penetration depth of the coating. Furthermore, CrSi, a high melting point metal silicide, is generated inside the CoCrAlSiY corrosion coating. Thus it is beneficial for improving the corrosion resistance of the coating.