Evolution of the structure and phase state of the heat-resistant intermetallic coating of operating turbine blades

The paper treats important problems of domestic engineering, namely, the urgent necessity to increase service life of large-sized turbine blades of the power gas-turbine stations operated on thermal power plants. The heat-resistant coating of the Ni–Co–Cr–Al–Y system with intermetallic phase structure β-(Ni, Me)Al + γ′-(Ni, Me)₃Al has been developed. It was made by high-energy plasma powder spraying and intended for protection of blade surface against high-temperature and erosive gas flow. The article studies microstructure, phase structure and physicomechanical properties of a coating given in an initial state, and after laboratory research of heat resistance and a post-operational state at ~29 000 hours (time of real operation of the gas-turbine engine of the GTE-45-3 power station on thermal power plant). After long-term operation, a decrease in the content of the intermetallic phase of β-(Ni, Ме)Al in the phase composition, an increase in the pore size and a decrease in the hardness of the coating have been established. At the same time, erosion resistance and heat-resistant properties of the coating remain, and, consequently, there is a sufficient resource.

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