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US RE39,320 E1Granted
Thermal barrier coating wrap for turbine airfoil
AssigneeGeneral Electric Company
InventorsGlenn H. Nichols, Judd Dodge Tressler
Life of this patent
Estimating the term…
Abstract
An airfoil having extended life due to reduction in stresses. The stresses are reduced by extending the thermal barrier coating below the radius between the outer band perimeter and the inner flow path surfaces and tapering the coating thickness. This additional tapered thermal barrier coating reduces the temperature gradient across a region already having high mechanical stresses resulting from geometric considerations thereby lowering thermally-induced stresses so that low cycle fatigue life is improved.
Claims51
An improved airfoil, the turbine nozzle comprising an airfoil having flow path surfaces that include a leading edge, a trailing edge, a concave side extending between the leading and trailing edges on a pressure side of the airfoil, and a convex side extending between the leading and trailing edge edges opposite the pressure side of the airfoil, an outer band perimeter that includes a tip portion and an outer band portion of the airfoil , and a fillet radius extending from the outer band portion perimeter, the fillet radius forming a smooth contour between the outer band portion perimeter and the leading edge, the trailing edge, the concave side of the blade airfoil and the convex side of the blade airfoil, the improvement comprising:
- a thermal barrier coating system that extends over a preselected region of the flow path surface that includes the outer band perimeter, the fillet radius and at least a portion of the flow path surface on at least one side of the airfoil between the trailing edge and about a midpoint between the trailing edge and the leading edge of the airfoil for a distance below the fillet radius sufficient to reduce cumulative stresses resulting from a combination of mechanically-induced stresses from the fillet radius and service-induced thermal stresses, the thermal barrier coating system including a bond coat applied over the preselected region of the airfoil substrate, an environmental aluminiding coating applied over at least the bond coat and a ceramic coating having low thermal conductivity applied over the bond coat and the aluminide coating.
An airfoil A turbine nozzle for service in the turbine portion of a gas turbine engine, said turbine nozzle comprising at least one airfoil comprised of:
- flow path surfaces that include a leading edge, a trailing edge, a concave side extending between the leading and trailing edges on a pressure side of the airfoil, and a convex side extending between the leading and trailing edge edges opposite the pressure side of the airfoil and airfoil, an outer band perimeter that includes a tip portion and an outer band portion of the airfoil, and a fillet radius extending from the outer band portion, the fillet radius forming a smooth contour between the outer band portion and the leading edge, the trailing edge, the concave side of the airfoil and the convex side of the airfoil;
- and
- a base integrally attached to the airfoil opposite the outer band perimeter;
- the airfoil having a thermal barrier coating system that coats the fillet radius, the outer band perimeter portion and a leading edge region of the flow path surfaces, the leading edge region including the concave side and the convex side of the airfoil from the leading edge to about a line bisecting the airfoil between the leading edge and the trailing edge and spanning the airfoil from the fillet radius to the base, and a preselected region including at least a portion of the flow path surface on at least one side of the airfoil between the trailing edge and about a line bisecting the airfoil between the trailing edge and the leading edge for a preselected distance below the fillet radius toward the base sufficient to reduce cumulative stresses in a region of the fillet radius resulting from a combination of mechanically-induced stresses from the fillet radius and service-induced thermal stresses in the region, the thermal barrier coating system being continuous with the thermal barrier coating system in the leading edge region for the preselected distance, the thermal barrier coating system including a bond coat applied over the preselected region of the airfoil substrate, an environmental aluminiding coating applied over at least the bond coat and a ceramic coating having low thermal conductivity applied over the bond coat and the aluminide coating.
1 more element
An airfoil A nozzle assembly for service in the turbine portion of a gas turbine engine, said nozzle assembly comprised of:
- at least one airfoil comprising flow path surfaces that include a leading edge, a trailing edge, a concave side extending between the leading and trailing edges on a pressure side of the airfoil, and a convex side extending between the leading and trailing edge opposite the pressure side of the airfoil and airfoil, an outer band perimeter that includes a tip portion and an outer band portion of the airfoil, and a fillet radius extending from the outer band portion, the fillet radius forming a smooth contour between the outer band portion and the leading edge, the trailing edge, the concave side of the airfoil and the convex side of the airfoil;
- a base integrally attached to the airfoil opposite the outer band perimeter;
- the airfoil having a thermal barrier coating system that coats the outer band perimeter portion, the fillet radius radius, and a region extending from the leading edge to at least about ⅔ of the distance to the trailing edge, and from the fillet radius for a preselected distance below the fillet radius toward the base sufficient to reduce cumulative stresses in a region of the fillet radius resulting from a combination of mechanically-induced stresses from the fillet radius and service-induced thermal stresses in the region, the thermal barrier coating system including a bond coat, an environmental aluminiding coating applied over at least the bond coat and a ceramic coating having low thermal conductivity applied over the bond coat and the aluminide coating.
A method to reduce cumulative stresses resulting from a combination of mechanically-induced stresses from the fillet radius and service-induced thermal stresses in an airfoil, comprising the steps of:
- providing a nozzle assembly having airfoil flow path surfaces that include a leading edge, a trailing edge, a concave side extending between the leading and trailing edges on a pressure side of the airfoil, and a convex side extending between the leading and trailing edges opposite the pressure side of the airfoil, and also having an outer band perimeter that includes a tip portion and an outer band portion of the airfoil, and a fillet radius extending from the outer band portion, the fillet radius forming a smooth contour between the outer band portion and the leading edge, the trailing edge, the concave side of the airfoil and the convex side of the airfoil;
- applying a bond coat along the leading edge from the outer band portion of the airfoil to a base of the airfoil;
- applying a bond coat in a leading edge region defined by the fillet radius, the outer band portion and a leading edge region of the flow path surfaces, the leading edge region including the concave side and the convex side of the airfoil from the leading edge to about a line bisecting the airfoil between the leading edge and the trailing edge and spanning the airfoil from the fillet radius to the base;
- applying a bond coat to a preselected region including at least a portion of the flow path surface on at least one side of the airfoil between the trailing edge and about a line bisecting the airfoil between the trailing edge and the leading edge for a preselected distance below the fillet radius toward the base sufficient to reduce cumulative stresses in a region of the fillet radius, the bond coat applied to the preselected region being continuous with the bond coat in the leading edge region for the preselected distance;
- applying a ceramic topcoat over the bond coat in the leading edge region and the preselected region.
2 more elements
A method to reduce cumulative stresses resulting from a combination of mechanically-induced stresses from the fillet radius and service-induced thermal stresses in an airfoil, comprising the steps of:
- providing a nozzle assembly having airfoil flow path surfaces that include a leading edge, a trailing edge, a concave side extending between the leading and trailing edges on a pressure side of the airfoil, and a convex side extending between the leading and trailing edges opposite the pressure side of the airfoil, an outer band perimeter that includes a tip portion and an outer band portion of the airfoil, and a fillet radius extending from the outer band portion, the fillet radius forming a smooth contour between the outer band portion and the leading edge, the trailing edge, the concave side of the airfoil and the convex side of the airfoil, the airfoil also having a thermal barrier coating applied to the leading edge;
- applying a bond coat to a preselected region including at least a portion of the flow path surface on at least one side of the airfoil between the trailing edge and about a line bisecting the airfoil between the trailing edge and the leading edge for a preselected distance below the fillet radius toward the base sufficient to reduce cumulative stresses in a region of the fillet radius, the bond coat applied to the preselected region being continuous with the thermal barrier coating applied to the leading edge region for the preselected distance;
- applying a ceramic topcoat over the bond coat in the preselected region.
A turbine nozzle for a gas turbine engine, said turbine nozzle comprising:
- at least one airfoil comprising flow path surfaces that include a leading edge, a trailing edge, a concave side extending between the leading and trailing edges on a pressure side of the airfoil, and a convex side extending between the leading and trailing edges opposite the pressure side of the airfoil;
- and
- an outer band perimeter that includes a tip portion and an outer band portion of the airfoil;
- a fillet radius extending from the outer band portion, the fillet radius forming a smooth contour between the outer band portion and the leading edge, the trailing edge, the concave side of the airfoil and the convex side of the airfoil;
- and
- a base integrally attached to the airfoil opposite the outer band perimeter;
- the airfoil having a thermal barrier coating system that coats the fillet radius, a portion of the outer band perimeter and a leading edge region of the flow path surfaces, the leading edge region including the concave side and the convex side of the airfoil from the leading edge to about a line bisecting the airfoil between the leading edge and the trailing edge and spanning the airfoil from the fillet radius to the base, and a preselected region including at least a portion of the flow path surface on at least one side of the airfoil between the trailing edge and about a line bisecting the airfoil between the trailing edge and the leading edge for a preselected distance below the fillet radius toward the base sufficient to reduce cumulative stresses in a region of the fillet radius resulting from a combination of mechanically-induced stresses from the fillet radius and service-induced thermal stresses in the region, the thermal barrier coating system being continuous with the thermal barrier coating system in the leading edge region for the preselected distance, the thermal barrier coating system including a bond coat applied over the preselected region of the airfoil substrate, and a ceramic coating having low thermal conductivity applied over the bond coat.
4 more elements
A turbine nozzle for a gas turbine engine, said nozzle comprising:
- a radially outer band;
- at least one airfoil extending from said outer bands, said airfoil comprising a first sidewall and a second sidewall connected together at a leading edge and a trailing edge,
- a fillet radius extending between said at least one airfoil and said outer band, said fillet radius extending between said airfoil leading and trailing edges and forming a substantially smooth contour between said at least one airfoil and said outer band;
- and
- a thermal barrier coating extending over at least a portion of the radially outer band, the fillet radius, and a pre-selected region of said airfoil extending across at least one of said airfoil first and second sidewalls from said airfoil leading edge aft to at least a midpoint between said airfoil leading and trailing edges and for a distance below said fillet radius sufficient to facilitate reducing stresses induced to said airfoil, said thermal barrier coating has a variable thickness measured across said airfoil.
2 more elements
Dependencies are inferred from the claim text.