Which components are repaired by plasma spray?

• A. Turbine blades and rotors
• B. Turbine casings and vanes
• C. Nozzle guide vanes only
• D. Fuel nozzles

Answer: (B)

Plasma spray is a coating process used to rebuild worn or damaged surfaces on hot-section turbine parts by depositing a protective layer that can restore dimensions and improve resistance to heat, wear, and corrosion. This technique is well suited for turbine casings and vanes because these parts have large, accessible surfaces in the hot gas path where surface rebuilds and protective coatings can be applied and machined to final tolerances. Restoring the mating surfaces in the casings and the vane passages helps seal, guide flow, and extend service life without replacing the entire part. In contrast, rotating blades and rotors require different repair methods due to the need for extreme precision, balance, and structural integrity, which makes plasma spray less appropriate for those components. Fuel nozzles are not typical targets for this repair method either, since their geometry and service conditions demand other processes.