Thermal stress relaxation type ceramic coated heat-resistant element and method for producing the same

A ceramic coated bucket and stationary blade part of a gas turbine comprising at heat resisting alloy mainly composed of at least one material selected from the group consisting of Ni and Co where a metal layer comprising an alloy superior to said heat resisting alloy in high-temperature corrosion and oxidation resistance is provided overlying at least a part of the portion of said parts which is exposed to combustion gas, an Al.sub.2 O.sub.3 ceramic thin film layer is provided overlying the metal layer, a first ZrO.sub.2 ceramic coating layer having dense texture is provided overlying the Al.sub.2 O.sub.3 ceramic thin film layer and a second ZrO.sub.2 ceramic coating layer having columnar texture is provided overlying the first ZrO.sub.2 ceramic coating layer having dense texture and cracks are present only in the second ZrO.sub.2 ceramic coating layer having columnar texture in a direction of thickness along a boundary of the columns.

A thermal stress relaxation type ceramic coated bucket and nozzle of gas turbines which comprises a heat-resisting alloy mainly composed of at least one material selected from the group consisting of Ni and Co, wherein on at least a part of the surface which is exposed to combustion gas is provided a metal layer comprising an alloy superior to the heat-resisting alloy in high-temperature corrosion and oxidation resistance and are further provided thereon, in succession, an Al.sub.2 O.sub.3 ceramic thin film layer and a ZrO.sub.2 ceramic layer or columnar texture comprising primary to tertiary columnar structures.

A bucket for gas turbines which has a blade part, a platform having a flat portion connected to the blade part, a shank part connected to the platform, a fin comprising projections provided on both sides of the shank part and a dovetail connected to the shank part, wherein a heat-resistant coating layer is provided on a surface of said blade part and the heat-resistant coating layer comprises a base, a metal layer comprising an alloy superior to the base in high-temperature corrosion and oxidation resistance overlying the base, an Al.sub.2 O.sub.3 ceramic thin film layer overlying the metal layer, a first ZrO.sub.2 ceramic coating layer comprising a dense particulate texture overlying the Al.sub.2 O.sub.3 ceramic thin film layer and a second ZrO.sub.2 ceramic coating layer of columnar texture overlying the first ZrO.sub.2 ceramic coating layer, cracks being present only in the second ZrO.sub.2 ceramic coating layer of columnar texture in a direction of thickness along a boundary of the columns.

A bucket for gas turbines which has a blade part, a platform having a flat portion and connected to the blade part a shank part, a fin comprising projections provided on both sides of the shank part and a dovetail connected to the shank part wherein a ZrO.sub.2 ceramic heat-resistant coating layer is provided on the surface of said blade part, the ZrO.sub.2 ceramic heat-resistant coating layer comprises a tertiary columnar texture comprising a plurality of secondary columnar textures composed of an aggregate of many primary columnar textures of ZrO.sub.2 ceramic, said tertiary columnar texture being divided by micro-cracks, said primary, secondary and tertiary columnar textures being distinguishable from one another.

A gas turbine in which buckets provided at a disk are rotated by colliding a combustion gas compressed by a compression against the buckets through a nozzle wherein the gas turbine has at least three stages of buckets, wherein each bucket at at least a first stage has a blade part, a platform having a flat portion connected to the blade part, a shank part connected to the platform, a fin comprising projections provided on both sides of the shank part and a dovetail connected to the shank part, wherein a heat-resistant coating layer is provided on a surface of the blade part of at least one of the bucket and the nozzle, the heat-resistant coating layer comprises a base, metal layer comprising an alloy superior to the base in high-temperature corrosion and oxidation resistance provided overlying the base, an Al.sub.2 O.sub.3 ceramic thin film layer overlying the metal layer, a first ZrO.sub.2 ceramic coating layer comprising a dense particulate texture overlying the Al.sub.2 O.sub.3 ceramic thin film layer and a second ZrO.sub.2 ceramic coating layer of columnar texture overlying the first ZrO.sub.2 ceramic coating layer, cracks being present only in the second ZrO.sub.2 ceramic coating layer of columnar texture in a direction of thickness along a boundary of the columns.

A ceramic coated heat-resistant element comprising a heat resisting alloy base mainly composed of a material selected from the group consisting of Ni, Co and a mixture of Ni and Co, and a heat-resistant coating layer provided on the surface of the base, wherein said heat-resistant coating layer comprises a metal layer of an alloy superior to the base in high-temperature corrosion and oxidation resistance overlying the base, an Al.sub.2 O.sub.3 ceramic thin film layer overlying the metal layer, a ZrO.sub.2 ceramic coating layer having a tertiary columnar texture overlying said Al.sub.2 O.sub.3 ceramic thin film layer, said tertiary columnar texture comprising a secondary columnar texture composed of at least one column, each of which comprises a primary columnar texture composed of primary columns, cracks being present only in said ZrO.sub.2 ceramic coating layer in a direction of thickness along a boundary of the columns, and said tertiary columnar texture being finely divided by micro-cracks.

A ceramic coated heat-resistant element comprising a heat resisting alloy base mainly composed of a material selected from the group consisting of Ni, Co and a mixture of Ni and Co, and a heat-resistant coating layer provided on the surface of the base, wherein said heat-resistant coating layer comprises a metal layer of an alloy superior to the base in high-temperature corrosion and oxidation resistance overlying the base, an Al.sub.2 O.sub.3 ceramic thin film layer overlying the metal layer, a ZrO.sub.2 ceramic coating layer having a secondary columnar texture overlying said Al.sub.2 O.sub.3 ceramic thin film layer, said secondary columnar texture comprising an aggregate of a plurality of primary columnar textures of ZrO.sub.2 ceramic material.