US Patent 7736704 Process for applying a protective layer

To protect a base metal layer (1) against high-temperature corrosion and high-temperature erosion, an adhesive layer (3) based on MCrAlY is applied to the base metal layer (1). The adhesive layer (3) is coated with an Al diffusion layer (4) by alitizing. The diffusion layer (4) is subjected to an abrasive treatment, so that the outer built-up layer (4.2) on the diffusion layer (4) prepared by alitizing is removed by the abrasive treatment. A ceramic heat insulation layer (2) consisting of zirconium oxide, which is partially stabilized by yttrium oxide, is applied to the diffusion layer (4) thus treated.