Geometrically Segmented Coating for Blade Outer Air Seal Spallation

The coating is divided into multiple segments including a geometrically segmented coating section with an array of cells (such as elongated grooves, sloped grooves, or cylindrical cells) and a non-geometrically segmented coating section. This segmentation allows different regions of the coating to serve different functions: the geometrically segmented portion dissipates internal stresses through faults in the cells, while the non-geometrically segmented portion provides continuous protection. The segmentation resolves the contradiction by enabling stress management without requiring complete redesign of the entire coating structure.

The coating is designed with non-uniform properties: the geometrically segmented coating section is applied specifically to the leading end and circumferential side where spallation is most likely to occur, while the non-geometrically segmented coating section is applied to other areas. This local differentiation allows the coating to provide enhanced stress relief and spallation resistance exactly where needed, rather than uniformly across the entire seal surface, thus improving reliability without excessive complexity.

The coating structure is segmented into cells (elongated grooves, sloped grooves, or cylindrical cells) that are designed to fail in controlled ways. When internal stresses develop, faults form within these cells rather than causing delamination from the substrate. This segmentation transforms the manufacturing challenge into a manageable process where the coating is applied as a continuous layer over a pre-formed cellular structure, rather than requiring complex multi-step coating processes.

The geometrically segmented coating structure is designed beforehand to accommodate and dissipate internal stresses that will inevitably develop during operation. The array of cells creates a framework that can absorb stress through internal faulting before the stress can propagate to cause spallation. This beforehand cushioning approach allows the coating to be applied using standard techniques while the underlying cellular structure provides the stress management capability.

The coating is applied with different geometric characteristics to different regions of the blade outer air seal. The geometrically segmented coating section is specifically applied to the leading end and circumferential side where spallation is most likely to occur due to blade encounter stresses. The non-geometrically segmented coating section is applied to other areas where continuous coverage is sufficient. This local quality approach targets protection precisely where needed while using simpler coating methods elsewhere, reducing the overall precision requirement compared to applying complex geometry everywhere.

The coating application is segmented into distinct zones: the geometrically segmented coating section covering the leading end and circumferential side, and the non-geometrically segmented coating section covering other areas. This segmentation allows each zone to be optimized independently for its specific functional requirements, with the geometrically segmented zone receiving enhanced protection and the other zones receiving standard protection, thereby managing manufacturing precision requirements effectively.