In order to improve solid particle erosion (SPE) resistance for steam turbine blades and nozzles, in corporation with Kobe Steel, Ltd., evaluation of hard coatings of TiN and TiAlN deposited by the Arc Ion Plating (AIP®) process was performed to verify applicability to an actual steam turbine. The results of high-temperature steam oxidation tests and room-temperature sand erosion tests showed that the TiAlN coating had high-temperature stability superior to that of the TiN coating, and erosion resistance far superior to that in the case of the conventional CrC thermal spray coating and boronizing treatment. High-temperature fatigue and creep tests showed that the characteristic strength of the blade material with the TiAlN coating was equal or superior to that of the base blade material.
On the basis of the results of comprehensive evaluation, it was confirmed that the TiAlN hard coating has excellent applicability to an actual steam turbine and it was successfully applied to steam turbine blades of power plants in Japan.
