BACKGROUND OF THE DISCLOSURE

The disclosure relates to a piston seal for a gas-turbine engine, more particularly to a wear resistant, self-lubricating seal for a mid-turbine-frame seal location of a gas turbine engine.

Piston rings and seals are utilized in numerous areas in gas turbine engines and can be utilized in areas such as the mid-turbine-frame seal areas which are subject to very high temperatures (approaching 1,600° F.) and also subject to vibratory motion which can lead to significant wear.

One configuration of piston rings for piston seal assemblies is made with nickel-based alloys such as large grain nickel-based superalloy. These materials can be age hardened austenitic nickel-based superalloys which improve creep resistance of the piston ring. However, piston rings made from this nickel-based superalloy still show significant wear to the ring as well as increased wear to the counterface. Specifically, it was found that chromia and alumina formed on the surface of the piston ring, when operated at high temperatures, and this resulted in increased friction leading to additional wear. Thus, the need remains for a piston ring suitable for use under the aforesaid conditions which has acceptable creep and wear resistance when used under these conditions.

SUMMARY OF THE DISCLOSURE

In one non-limiting configuration, a seal assembly for a gas turbine engine comprises a seal comprised of a nickel-based superalloy; a component in contact with the seal and defining a seal-counterface; and a coating on the seal at the seal-counterface, wherein the coating comprises a ternary oxide.

In another non-limiting configuration, the ternary oxide contains a metal oxide that forms nanoparticles when subjected to sliding or vibratory motion.

In still another non-limiting configuration, the ternary oxide comprises a silver-based ternary oxide.

In a further non-limiting configuration, the silver-based ternary oxide is selected from the group consisting of Ag3VO4, AgTaO3, Ag2MoO4and combinations thereof.

In a still further non-limiting configuration, the ternary oxide comprises a copper-based ternary oxide.

In another non-limiting configuration, the copper-based ternary oxide is selected from the group consisting of CuTa2O6, CuTaO3, CuMoO4and combinations thereof.

In still another non-limiting configuration, the ternary oxide is a calcium ternary oxide.

In a further non-limiting configuration, the calcium ternary oxide is selected from the group consisting of CaSO4, CaWO4, CaMoO4and combinations thereof.

In a still further non-limiting configuration, the coating is a thermal spray coating having a thickness of between 0.5 and 10 mils.

In another non-limiting configuration, the coating is a PVD coating and has a thickness of between 0.004 and 1.5 mils.

In still another non-limiting configuration, the seal comprises an age hardening austenitic nickel-based superalloy.

In a further non-limiting configuration, the seal has non-contact surfaces that are not in contact with the component, and the coating is on the seal at the seal-counterface, and not on the non-contact surfaces.

In a still further non-limiting configuration, the component comprises two components, with the seal mounted between the two components to define two seal-counterfaces, and the coating is on the seal at both of the two seal-counterfaces.

In another non-limiting configuration, the two components comprise a mid-turbine-frame (MTF) vane and an outer air seal.

A further non-limiting configuration is a seal for a gas turbine engine, comprising a seal comprised of a nickel-based superalloy and a coating on the seal, wherein the coating comprises a ternary oxide.

In another non-limiting configuration, the ternary oxide contains a metal oxide that forms nanoparticles when subjected to sliding or vibratory motion.

In still another non-limiting configuration, the ternary oxide comprises a silver-based ternary oxide.

In a further non-limiting configuration, the silver-based ternary oxide is selected from the group consisting of Ag3VO4, AgTaO3, Ag2MoO4and combinations thereof.

In a still further non-limiting configuration, the ternary oxide comprises a copper-based ternary oxide.

In another non-limiting configuration, the copper-based ternary oxide is selected from the group consisting of CuTa2O6, CuTaO3, CuMoO4and combinations thereof.

The details of one or more embodiments of the disclosure are set forth in the accompanying drawings and the description below. These embodiments, and features thereof, can be considered separately and also in combination within the scope of this disclosure. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.

