Can damaged TBC coatings be repaired, and what methods are used?
Repairability of TBC Systems
Yes, damaged Thermal Barrier Coatings (TBCs) can be repaired, and in aerospace maintenance cycles, refurbishment is an essential part of keeping turbine components operational. When erosion, cracking, or spallation occurs, the coating is typically stripped, inspected, and re-applied rather than replaced entirely. This approach is widely adopted on turbine blades and vanes produced via superalloy single crystal casting and components operating in the hot gas path of aerospace engines or power-generation turbines.
The key to successful repair is to restore adhesion between the bond coat and ceramic topcoat while preserving the substrate integrity of high-temperature alloys such as Inconel 738C or Rene 65.
TBC Repair Methods
The most widely used repair techniques include:
Stripping and Recoating – Existing TBC is removed using chemical or abrasive methods, followed by fresh application using TBC spraying technologies such as plasma spraying or EB-PVD.
Localized Spot Repair – Small damaged areas are prepared using grit blasting and selectively recoated without full stripping, reducing downtime.
Bond Coat Restoration – If adhesion loss originates at the interface, the bond coat may be reapplied using HVOF or low-pressure plasma spraying before ceramic recoating.
Heat Treatment After Repair – Thermal cycles are applied to improve bonding performance and relieve residual stress, especially when coating turbine vanes manufactured by superalloy equiaxed crystal casting.
Inspection and Post-Processing
After repair, advanced inspections such as X-ray, CT scanning, and material testing and analysis are used to verify coating adhesion, detect subsurface defects, and assess thermal fatigue cracking. Components may also require precision finishing through superalloy CNC machining to restore aerodynamic profiles or sealing surfaces.
In most aerospace maintenance programs, TBC repair is planned in conjunction with scheduled overhaul intervals, providing a cost-effective alternative to full component replacement while ensuring thermal protection remains within design limits.
