Method for coating a blade and blade of a gas turbine
View Patent ↗A method is provided for coating a hollow, internally cooled blade ( 1 ) of a gas turbine, in which method an outer coating ( 5 ) comprising an MCrAlY-based bonding layer ( 6 ) and a ceramic thermal barrier layer ( 9 ) of zirconium oxide is applied to the base material ( 3 ) of the blade ( 1 ) on the outer side of the blade ( 1 ) and an inner coating ( 4 ) comprising a Cr diffusion layer ( 7 ) is applied to the base material ( 3 ) of the blade ( 1 ) on the inner side of the blade ( 1 ). The MCrAlY-based bonding layer ( 6 ) is thereby applied to the finished blade ( 1 ). At the same time, along with the inner coating ( 4 ), the Cr diffusion layer ( 7 ) is also applied to the MCrAlY-based bonding layer ( 6 ) of the outer coating ( 5 ) by chemical vapor deposition. Subsequently, an Al diffusion layer ( 8 ) and an outer brittle Al build-up layer are applied by chemical vapor deposition to the bonding layer ( 6 ) coated with the Cr diffusion layer ( 7 ). After that, the outer brittle Al build-up layer is removed by an abrasive treatment and the ceramic thermal barrier layer ( 9 ) is applied to the Al diffusion layer ( 8 ).
1. A method for coating a hollow, internally cooled blade of a gas turbine, comprising:
applying onto an outside surface of a base material of the blade an outer coating comprising a MCrAlY-based bonding layer;
applying, by chemical vapor deposition, an inner coating consisting of a first Cr diffusion layer to an inside surface of the blade;
applying a second Cr diffusion layer to the MCrAlY-based bonding layer of the outer coating, wherein the steps of applying the first Cr diffusion layer and applying the second Cr diffusion layer are performed simultaneously;
applying an Al diffusion layer and an outer brittle built-up Al layer by chemical vapor deposition to the bonding layer coated with the second Cr diffusion layer;
removing the outer brittle built-up Al layer by an abrasive treatment; and
applying, after the step of removing, a ceramic heat-insulating layer of zirconium to the Al diffusion layer.
2. The method according to claim 1 , further comprising:
subjecting the blade to a solution heat treatment before removing the outer brittle built-up Al layer by the abrasive treatment abrasive.
3. The method according to claim 1 , wherein the bonding layer is applied as a cladding layer by plasma or high-velocity spraying.
4. The method according to claim 2 , wherein the bonding layer is applied as a cladding layer by plasma or high-velocity spraying.
5. A hollow, cooled blade of a gas turbine, comprising:
an outer coating comprising a MCrAlY-based bonding layer and a ceramic heat-insulating layer of zirconium oxide applied to an outside surface of the blade on a base material of the blade;
an inner coating consisting of a first Cr diffusion layer applied to an inside surface of the blade; and
a second Cr diffusion layer and an Al diffusion layer arranged in the outer coating;
wherein the ceramic heat-insulating layer is applied to the MCrAIY-based bonding layer of the outer coating subsequent to removal of an outer brittle built-up layer by an abrasive treatment.