Layer system with a structured substrate surface and production process

A component of a gas turbine engine including a layer system, said layer system comprising:

• a substrate,
• at least two layers comprising an inner layer and an outer layer,
• wherein the inner layer is on a boundary surface of the substrate,
• wherein the boundary surface of the substrate has both a roughness on the surface and an additional waviness to the surface that takes a sinusoidal form, wherein the roughness has roughness elevations and roughness depressions that define a roughness difference (R's) and the waviness has waviness peaks and waviness troughs that define a waviness difference (R4i), and wherein the waviness difference (R4i) is at least 20% greater than the roughness difference (R's);
• and wherein a surface of the inner layer at an interface to the outer layer has both a roughness on the surface and an additional waviness to the surface that takes a sinusoidal form, wherein the roughness has roughness elevations and roughness depressions that define a roughness difference (Rs) and the waviness has waviness peaks and waviness troughs that define a waviness difference (R7i), and wherein the waviness difference (R7i) is at least 20% greater than the roughness difference (Rs).