Abradable properties of porous YSZ coatings

In order to obtain an abradable seal coating which is used in high temperature, a porous yttria-stabilized zirconia (YSZ) coating was deposited by the plasma spraying technology. The coating porosity achieved to 2.1% merely by utilizing commercial YSZ powder. A polyester powder coated by TiO₂ was blend into the YSZ powder to increase the porosity of the coating. It was shown that the coating porosity increased to 12.3%, 28.5% and 29.7% when the mass percent of the coated polyester powder got up to 10%, 30% and 50%, respectively. Then the mean diameter of the pore in coatings reached to 14.4, 18.5 and 25.4 μm respectively as well. The decreasing hardness was presented with the increase of coating porosity. The higher porosity aroused lower friction force and coefficient in an abrasion condition. The weight loss of the coatings increased by about 3 times with the porosity increasing to about 30% from 2.1%, and the weight loss of the rotated pins decreased by 50%. Thus it can be seen, the abradable property of YSZ coatings can be improved through a porosity promoting process.