Ceramic-based thermal spray coatings have been lately introduced as abradable materials for applications in the hot section of gas turbine engines. This paper reports abradable characteristics and high-temperature oxidation resistance of plasma sprayed yttria-stabilized zirconia (YSZ) and agglomertated yttria-stabilized zirconia with Polyester (YSZP). Unlike conventional blended coatings, agglomerated YSZP plasma-sprayed coatings are more forgiving to technique and processing parameter variations during the thermal-spray operation. The abradability studies were conducted on a test rig at temperatures of 600, 900 and 980 °C using coated (hardened) and uncoated blades. The oxidation resistance of the coatings was measured as a function of the cycles to failure and was conducted at temperature ranges of 930 to 1150°C in still air. Results showed that the ceramic coating, YSZ-Pl, was capable of withstanding both mid- and high-temperature rubs with little deleterious effects to the uncoated blade-tip across the temperature range, and presented a cyclic oxidation resistance comparable to that of YSZ coating.

Various low-temperature abradable coatings for applications reaching 482°C were evaluated with the purpose of being applied onto the compressor spacers of an 11 MW land-based gas turbine engine. The coating is intended to reduce the compressor rotor tip-clearance, and is expected to increase the compressor efficiency by a range of 0.5 to 1%. This study evaluated physical and metallurgical characteristics, abradable and oxidation-resistance properties of plasma-sprayed AlSi-BN, NiCrFeAl-BN and quasicrystal AlCuFeCr, and flame-and plasma-sprayed NiCrFeAl-BN.