Complex ZrO2-Y2O3 sol were prepared from precursors of inorganic salts and metal alkoxides. The processes for complex ZrO2-Y2O3 sol preparation and purification, the sol-gel transformation and the characterization of the sol from the two kinds of precursors were discussed and compared. It was found that the colloidal particles were amorphous in nature, and extremely fine (<10nm) in the both cases. ZrO2-Y2O3 coatings on GH220 superalloy samples MCrAlX (M=Fe, Co, Ni, X=Y, Ta,Hf…) pre-coated) were prepared using sols from the two different processes and tested at 1000 ℃ for 100 h in laboratory air. Results showed that only the coatings from the metal alkoxides derived sol offered excellent oxidation resistance.
