Single-crystal article having crystallographic orientation optimized for a thermal barrier coating

In a single-crystal nickel-base superalloy turbine blade having a thermal barrier coating system on a surface thereof, the turbine blade being characterized by having been unidirectionally solidified along a primary crystallographic direction substantially parallel to the surface and corresponding to a <001>

• crystallographic direction of the turbine blade, the thermal barrier coating system having a life-limiting surface region characterized by a combination of in-service temperature and strain levels that promote spallation of the thermal coating system having a life-limiting surface region prior to other regions of the thermal barrier coating system, wherein the improvement comprises:
• the turbine blade having a secondary <001>
• crystallographic direction normal to the primary crystallographic direction and oriented about 20 to about 45 degree from a direction normal to the life-limiting surface region of the thermal barrier coating.

A method for promoting the service life of coating on a single-crystal article, the method comprising the steps of:

• identifying a surface of the single-crystal article corresponding to a life-limiting surface region of the coating, the life-limiting surface region being characterized by a combination by a combination of temperature and strain levels that promote spallation of the coating in the life-limiting surface region prior to other regions of the coating;
• casting the single-crystal article to solidify unidirectionally along a primary crystallographic direction that is substantially parallel to the surface and such that a secondary crystallographic direction normal to the primary crystallographic direction is oriented about 20 to about 45 degrees from a direction normal to the life-limiting surface region of the coating, and then forming the coating on the single-crystal article.