Study on the optimal phase structure of recovered steam turbine blades using different technological spray modes for deposition of Al2O3

Laser-plasma renewal of steam turbine blades presents rational approach to improve manufacturability and reduce the cost of the recovery process. The phase composition of recovered material determines turbine blades durability. However, the excising technologies do not take into account the material phase composition. This paper presents the methodology and main results from a study of the phase structure of a turbine blade recovered by laser-plasma spraying of Al2O3. It has been established that thermodynamic processes played an important role in increasing the adhesion of Al2O3 particles to the metal surface. The technological conditions were varied in order to obtain optimal martensitic - ferrite class phase structure of recovered steam turbine blades. Specific conditions for coating deposition that assure optimal phase structure of a material with high mechanical properties and increased durability were proposed.