Alluminide coatings containing silicon and yttrium for superalloys and method of forming such coatings

Abstract

Aluminide coatings or layers (14) for jet engine components (10) and a process for forming aluminide layers (14) that include additions of silicon and yttrium. A superalloy substrate (12) of the component (10) is initially coated with a layer of a silicon-containing material. The substrate (12) is then aluminided, for example by a chemical vapor deposition process, and is exposed to a yttrium-containing material during the aluminiding process to form the aluminide layer (14) containing silicon and yttrium. A ceramic thermal barrier layer (24) of yttria-stabilized zirconia may be optionally applied over the aluminide layer (14). Another optional zirconia layer (26) maybe provided between the aluminide layer (14) and the ceramic thermal barrier layer (24). The present invention provides a silicon- and yttrium-containing aluminide layer (14) having improved durability, either as a standalone environmental coating or as a bond coat for a subsequently-applied ceramic thermal barrier layer (24).

Description

FIELD OF THE INVENTION [0001] The present invention relates to formation of an intermetallic layer on a metal component and, more particularly, to formation of an intermetallic layer on an airflow surface of a jet engine metal component. BACKGROUND OF THE INVENTION [0002] Intermetallic layers are often applied to a surface of a metal component for protecting the underlying metal substrate of the component and thereby extending its useful life during operation. For example, the aerospace industry coats many components having airflow surfaces in a jet engine, like turbine blades, vanes, and nozzle guides, with an aluminide layer to protect the underlying base metal from high temperature oxidation and corrosion. [0003] A ceramic thermal barrier coating may be applied over the aluminide layer to insulate the jet engine component from combustion and exhaust gases, permitting the combustion and exhaust gases from the engine to be hotter than would otherwise be possible with an aluminide l...

AI Technical Summary

Benefits of technology

[0010] By virtue of the foregoing, there is provided an improved environmental coating, bond coat, and method of forming such coatings that include an aluminide layer containing minor concentrations of silicon and yttrium. The aluminide coating of the invention is competitive in performance with platinum aluminide and less expensive to produce than platinum aluminide.

Problems solved by technology

However, such protective ceramic thermal barrier coatings may not adhere well directly to the superalloys commonly used to form jet engine components and, while in service, tend to spall.

However, platinum aluminides are expensive to produce, which contributes to increasing the cost of jet engine components and the cost of refurbishing used jet engine components.

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