| abstract |
Disclosed herein is an article comprising one or more channels and a multi-layer protective coating on the one or more channels. The multi-layer protective coating includes an anodization layer comprising a plurality of cracks and a plurality of pores, a sealing layer on the anodization layer, and a top layer on the sealing layer. The sealing layer comprises a metal oxide, the seals the plurality of cracks and the plurality of pores, and has a porosity of approximately 0%. The top layer comprises a rare earth oxide, a rare earth fluoride, or a rare earth oxyfluoride, has a different material composition than the sealing layer, and has a porosity of approximately 0%. |