Fabrication and Cyclic Oxidation of Y2O3/CeO2-Modified Low Temperature Aluminide Coatings

With Y2O3/CeO2 powder, instead of part of Al2O3, acting as filler, Y2O3/CeO2-modified aluminide coatings were produced on Ni based using a conventional pack-cementation method at 600 °C for 10 h. For comparison, a normal aluminide coating was also produced using pure Al2O3 acting as filler. Effect of Y2O3/CeO2 in the pack on the alumina phase transformation and cyclic oxidation resistance in air at 1000 °C was investigated. The results indicate that Y2O3 and CeO2 have different effects on θ-α phase transformation: Y2O3 suppresses the growth of the θ-alumina but CeO2 promotes the q-a phase transformation. However, compared to the normal aluminide coating, the addition of Y2O3/CeO2 significantly improves the cyclic oxidation resistance due to the formation of adherent alumina scale, especially the later. The effects of Y2O3/CeO2 on alumina phase transformation and cyclic oxidation resistance were discussed.