Ni-BASED SUPERALLOY COMPONENT HAVING HEAT-RESISTANT BOND COAT LAYER FORMED THEREIN

Abstract

Provided is an Ni-based superalloy component having a three-layer configuration of an Ni-based superalloy substrate, a bond coat layer and a top coat layer, wherein the alloy material of the bond coat layer has a composition including Co of at most 15.0% by mass, Cr of from 0.1% by mass to 7.5% by mass, Mo of at most 3.0% by mass, W of from 4.1% by mass to 10.0% by mass, Al of from 6.0% by mass to 10.0% by mass, Ti of at most 2.0% by mass, Ta of from 5.0% by mass to 15.0% by mass, Hf of at most 1.5% by mass, Y of at most 1.0% by mass, Nb of at most 2.0% by mass and Si of at most 2.0% by mass with a balance of Ni and inevitable impurities, and the Ni-based superalloy substrate has a composition including Al of from 1.0% by mass to 10.0% by mass, Ta of from 0% by mass to 14.0% by mass, Mo of from 0% by mass to 10.0% by mass, W of from 0% by mass to 15.0% by mass, Re of from 0% by mass to 10.0% by mass, Hf of from 0% by mass to 3.0% by mass, Cr of from 0% by mass to 20.0% by mass, Co of from 0% by mass to 20% by mass, Ru of from 0% by mass to 14.0% by mass, Nb of from 0% by mass to 4.0% by mass, Ti of from 0% by mass to 4.0% by mass and Si of from 0% by mass to 2.0% by mass with a balance of Ni and inevitable impurities. The Ni-based superalloy component has the heat-resistant bond coat layer formed therein and is extremely excellent in environmental characteristics such as oxidation resistance and high-temperature corrosion resistance, especially having a long heat cycle life, and is favorable for turbine blades and vanes.

Description

TECHNICAL FIELD [0001]The present invention relates to an Ni-based superalloy component having a heat-resistant bond coat layer formed therein. Concretely, the invention provides an Ni-based superalloy component having a heat-resistant bond coat layer formed therein, which is for use for turbine rotor vanes or turbine stator vanes for jet engines, industrial gas turbines and others under high-temperature and high-stress conditions, and which improves the environmental characteristics such as oxidation resistance, high-temperature corrosion resistance and the like of components and dramatically prolongs the thermal cycle life thereof, which, however, has theretofore been especially difficult to prolong in conventional arts.BACKGROUND ART[0002]Heretofore, as substrates for turbine rotor blades or turbine stator vanes for jet engines, industrial gas turbines and others, Ni-based superalloys have been developed, of which the serviceable temperature has been improved. For further enhanci...

AI Technical Summary

Benefits of technology

The invention has prevented the formation of a secondary reaction layer between the bond coat material and the alloy substrate in a severe condition of high temperature. Additionally, a homogeneous and dense oxide layer is formed at the near-interface of the bond coat layer adjacent to the ceramic thermal barrier coat layer, which enhances the stability and adhesiveness of the oxide layer. This results in a significantly longer heat cycle life of the coated components compared to conventional methods.

Problems solved by technology

However, when these bond coat materials are applied to Ni-based superalloy turbine vanes and when the turbine vanes are used at a high temperature for a long period of time, then mutual diffusion of elements may go on via the near-interface between the Ni-based superalloy substrate and the bond coat material and / or via the near-interface between the ceramic thermal barrier coat material and the bond coat material, and owing to the mutual diffusion of elements, the Ni-based superalloy material may be deteriorated, thereby providing some problems of material technology in point of durability reduction of turbine vanes themselves including strength reduction as well as environment resistance reduction of the bond coat material.

High-pressure turbine blades have a hollow structure for cooling, but their wall thickness is being reduced in the art, and therefore, the influence of the diffusion region brings about much more serious technical problems.

For retarding the mutual diffusion of elements through the near-interface of Ni-based superalloy substrate / bond coat material, a diffusion barrier coating with a special alloy layer formed therein has been investigated; however, cases that could not always sufficiently attain the object of diffusion barrier coating are not negligible (see the following Patent Reference 4).

Ralph J. Hecht et al. and Edward Harvey Goldman et al. proposed bond coat materials having alloy compositions differing from those of Ni or Co aluminide, MCrAlY and others heretofore widely used in the art, and asserted the improvements thereof; however, it could not be said that their bond coat materials could fully fulfill the severe heat-resistant serviceable conditions required at present (see the following Patent References 5 and 6).

For increasing the heat resistance of the Ni-based superalloy substrate (1), in general, the surface of the substrate is coated with a ceramic thermal barrier coat layer (3), however, the long-term adhesive property of the interface between the Ni-based superalloy substrate and the ceramic thermal barrier coat layer is insufficient, and therefore various coat materials are sued as the bond coat material (2).

Consequently, the current state is that the life of Ni-based superalloy components in use at high temperatures could not always be said to be satisfactory.

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