A Study on YSZ Abradable Seal Coatings Prepared by Atmospheric Plasma Spray and Mixed Solution Precursor Plasma Spray

The yttria-stabilized zirconia (YSZ) ceramic has been proved to be a promising material for abradable seal coatings. In this research, abradable seal coatings named C-YSZ and M-YSZ were prepared by applying the conventional plasma spraying method with improved nanostructured powders and by the mixed solution precursor plasma spraying technique, respectively. A study on the microstructure, mechanical properties, oxidation resistance and hot corrosion resistance was conducted on both C-YSZ and M-YSZ coatings by using scanning electron microscopy, transmission electron microscopy, muffle furnace and x-ray diffractometer. The results show that the C-YSZ coating presents larger-size pores with denser YSZ structures and grains showing size larger than 100 nm distributed around the pores compared with M-YSZ, in which the pores are much smaller and the grain size is 20-30 nm. As a result, the M-YSZ coating displays lower hardness and bond strength compared with C-YSZ. The oxidation tests show that the M-YSZ coating possesses better oxidation resistance due to the nanostructure topcoat compared with C-YSZ. However, the hot corrosion tests indicate that both the C-YSZ coating and the M-YSZ coating fail to present ideal hot corrosion resistance.