Ceramic Coating Removal via Caustic Immersion and Water Jet Blasting

The invention segments the ceramic coating removal process into two distinct stages: first using caustic solution to chemically weaken and remove the ceramic coating, then using water jet blasting only to remove residual ceramic material. This segmentation allows each method to be optimized for its specific function, preventing the metallic bond coating damage that occurs when water jet blasting is used alone for complete removal.

The caustic solution acts as an intermediary substance that facilitates the removal process. It chemically attacks and weakens the ceramic coating structure, creating a compromised state that allows subsequent water jet blasting to remove only residual ceramic material without directly impacting the metallic bond coating. The intermediary chemical treatment mediates between the aggressive mechanical removal and the protective requirement for the bond coating.

The invention creates a universal removal process that works for both porous columnar grain and dense lamellae microstructure ceramic coatings. The two-stage approach combines chemical treatment (effective for porous structures) with mechanical treatment (effective for dense structures), making the overall process adaptable to different ceramic microstructures. The water jet blasting stage provides the versatility needed to handle dense coatings that resist chemical attack alone.

The invention changes the parameters of the removal process by introducing chemical treatment parameters (caustic solution concentration, temperature, immersion time) followed by mechanical treatment parameters (water pressure, jet velocity). This parameter transformation allows the process to adapt to different ceramic microstructures - the chemical parameters address porous structures while the mechanical parameters address dense structures, achieving broad versatility.

The caustic solution treatment is performed as a preliminary action before water jet blasting. This preliminary chemical treatment weakens and removes the bulk of the ceramic coating, reducing the amount of material that subsequent water jet blasting needs to remove. By performing the aggressive removal action first, the need for repeated water jet blasting is eliminated, preventing erosion of the metallic bond coating.

The invention replaces purely mechanical removal (water jet blasting) with a combined chemical-mechanical system. The chemical action of the caustic solution substitutes for the mechanical force that would otherwise be required to remove dense ceramic material through repeated blasting. This substitution reduces the cumulative mechanical stress on the metallic bond coating, preventing material loss and surface roughness reduction.

The removal process is segmented into chemical treatment followed by brief mechanical treatment. The caustic solution penetrates and weakens the ceramic coating on convex surfaces during immersion, eliminating the need for prolonged water jet blasting. This segmentation reduces the duration of mechanical action required, preventing bond coating damage while achieving complete ceramic removal from difficult-to-reach convex surfaces.

The caustic solution serves as an intermediary that facilitates access to and removal of ceramic coating on convex surfaces. It chemically penetrates the ceramic structure regardless of surface geometry, weakening the bond between ceramic and metal. This intermediary chemical action eliminates the need for extended mechanical blasting time on convex surfaces, reducing the duration of harmful mechanical action while achieving complete removal.