Patent ID: RE39320

Claim:
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.