Patent Description:
Systems that operate in extreme environments, such as the high temperatures and pressures experienced inside a gas turbine engine, must be able to withstand these environments while still exhibiting favorable wear characteristics. Historically, seals in gas turbine engines have been made from various materials, such as INCONEL® <NUM>, INCONEL X-<NUM>, or other nickel-based alloys. However, as operating temperatures within the gas turbine engine increase, there is a need for seals that can withstand these environments.

<CIT> discloses a prior art dynamic sealing material and manufacturing method, wherein said dynamic sealing material including AlCoCrFeNi high-entropy alloy material and wherein to improve its wear resistance thermoplastic polyimide and lubricants, having the characteristics of low friction coefficient and easy formation of transfer film, were filled in the porous structure of the AlCoCrFeNi high entropy alloy. The use temperature of the dynamic sealing material prepared is preferably -<NUM> to <NUM>.

<CIT> discloses a prior art method for identifying and forming high entropy alloys via additive manufacturing.

<CIT> discloses a prior art alloy member.

<CIT> discloses a prior art alloy material.

According to a first aspect of the present invention, there is provided a tribological and creep resistant system as set forth in claim <NUM>.

In a further embodiment of any of the above, the seal body forms a complete ring.

In a further embodiment of any of the above, the system is configured to operate at temperatures up to <NUM>.

In a further embodiment of any of the above, a gas turbine engine with the seal body is located radially outward of a core airflow path through the gas turbine engine in a turbine section of the gas turbine engine.

In a further embodiment of any of the above, a gas turbine engine with the seal body is located radially outward of a core airflow path through the gas turbine engine in a high pressure compressor of the gas turbine engine.

In a further embodiment of any of the above, the seal body includes at least one bend.

In a further embodiment of any of the above, the at least one bend includes multiple bends on one of a radially inner side or a radially outer side of the seal body. Only a single bend is on the other of the radially inner side or the radially outer side.

In a further embodiment of any of the above, the first component is a vane and the second component is a blade outer air seal.

In a further embodiment of any of the above, a first component defines a groove that seats a radially inner portion of the seal body. The seal body defines a piston seal.

In a further embodiment of any of the above, the first component is a mid-turbine frame vane and the groove is located on a radially outer portion of the mid-turbine frame vane.

According to a further aspect of the invention, there is provided a method as set forth in claim <NUM>.

In a further embodiment of any of the above, the powdered high entropy alloy utilizes a powdered bed of the high entropy alloy. Forming the powdered high entropy alloy into the seal body with the heat source includes welding or melting adjacent layers of the high entropy alloy in the powdered bed to form a desired shape of the seal body.

In a further embodiment of any of the above, providing the powdered high entropy alloy includes blowing streams of the powdered high entropy alloy.

In a further embodiment of any of the above, forming the powdered high entropy alloy into a seal body with the heat source includes controlling the heat source to weld or melt the high entropy alloy into a desired shape of the seal body.

In a further embodiment of any of the above, the seal body extends from a leading edge to a trailing edge and includes at least one bend.

In a further embodiment of any of the above, the seal body extends from a leading edge to a trailing edge and defines a piston seal.

In a further embodiment of any of the above, the seal body forms a complete ring of sufficient diameter to surround a core air flow path in a gas turbine engine.

The fan section <NUM> drives air along a bypass flow path B in a bypass duct defined within a housing <NUM>, such as a fan case or nacelle, and also drives air along a core flow path C for compression and communication into the combustor section <NUM> then expansion through the turbine section <NUM>.

It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present disclosure is applicable to other gas turbine engines including direct drive turbofans.

The fan section <NUM> of the engine <NUM> is designed for a particular flight conditiontypically cruise at about <NUM> Mach and about <NUM>,<NUM> feet (<NUM>,<NUM> meters).

<FIG> illustrates an example seal <NUM>, such as a "W"-shape seal, in contact with a first counterface 63A located upstream of the seal <NUM> and a second counterface 63B located downstream of the seal <NUM>. In the illustrated example, the seal <NUM> is located in the high pressure turbine <NUM>. However, the seal <NUM> could be located in other parts of the gas turbine engine <NUM> such as the compressor section <NUM>, the combustor section <NUM>, or other areas of the turbine section <NUM>. An upstream portion of the seal <NUM> engages the first counterface 63A on a blade outer air seal <NUM>, such as a ceramic blade outer air seal, adjacent a turbine blade <NUM>. A downstream portion of the seal <NUM> engages the second counterface 63B on a structure 64A, such as a vane hook, on a vane, such as an exit guide vane <NUM>. The seal <NUM> creates a separation or barrier between a hot fluid area <NUM> and a cold fluid area <NUM>. Wear typically occurs in a wear area <NUM> that includes the seal friction surface on the seal <NUM>. In one example, the seal <NUM> is configured to operate in the gas turbine engine <NUM> at temperatures in excess of <NUM> and in another example, the seal <NUM> is configured to operate in the gas turbine engine <NUM> at temperatures in excess of <NUM>.

As shown in <FIG>, the seal <NUM> has an inner diameter <NUM>, an outer diameter <NUM>, a radial height <NUM>, and a width <NUM> in an axial direction. The seal <NUM> includes a body portion <NUM> extending between a leading edge <NUM> and a trailing edge <NUM>. The seal <NUM> further includes a plurality of bends <NUM> disposed between the leading edge <NUM> and the trailing edge <NUM>. The plurality of bends <NUM> can be any one of a trough, ridge, or other geometric profile. In the illustrated example, the seal <NUM> includes two bends adjacent the inner diameter <NUM> and a single bend adjacent the outer diameter <NUM>. However, other bend configurations could include at least one bend adjacent either the leading edge <NUM> or the trailing edge <NUM> or both the leading and trailing edges <NUM>, <NUM>.

The body portion <NUM> defines a complete ring without any separations or discontinuities in the circumferential or axial directions. Alternatively, the body portion <NUM> may include a separation or discontinuity and not form a complete ring. In this disclosure, radial or radially, axial or axially, and circumferential or circumferentially is in relation to the engine axis A unless stated otherwise. Additionally, upstream and downstream is in relation to a general direction of air flow through a core of the gas turbine engine <NUM> unless stated otherwise.

In the illustrated example, the cross-sectional shape is a two-dimensional shape represented by a cross-section of the seal <NUM> with the cross-sectional shape being substantially the same at a plurality of circumferential locations around the seal <NUM>. While the seal <NUM> is illustrated with a cross-sectional shape in the form of a "W," the seal <NUM> can be of any shape for the application in which it is used such that the seal's shape is application-specific. In other embodiments, the cross-sectional shape of the seal can be an "O"-shape, a "C"-shape, an "E"-shape, a "M"-shape, a "U"-shape, a Diamond-shape, a Dogbone-shape, a Feather-shape, a Bathtub-seal shape, a Wire-seal shape, or any other geometric shape.

<FIG> illustrate another example seal, such as a piston seal <NUM>. The piston seal <NUM> is similar in composition and manufacturing as the seal <NUM> except where described below or shown in the Figures. In the illustrated example, the piston seal <NUM> is disposed in a mid-turbine frame vane <NUM> aft outside diameter seal groove <NUM> and against a portion of the engine static structure <NUM>. In this example embodiment, wear typically occurs in a wear area <NUM> that includes the seal friction surface on the seal <NUM> and a corresponding counterface on the mid-turbine frame vane <NUM> with the mid-turbine frame vane <NUM> being formed from a nickel-based alloy, such as Mar-M247.

The seal <NUM> has an inner diameter <NUM>, an outer diameter <NUM>, a radial height <NUM>, and a width <NUM> in an axial direction. In the illustrated example, the height <NUM> is greater than the width <NUM>, such that the seal <NUM> includes a rectangular cross section. The seal <NUM> includes a body portion <NUM> extending from a leading edge <NUM> to a trailing edge <NUM>. The body portion <NUM> follows a constant cross-sectional shape and forms a complete ring without any separations or discontinuities in a circumferential or axial direction. Alternatively, the seal <NUM> could include a separation or discontinuity.

The seals <NUM>, <NUM> are formed from high entropy alloys ("HEA") including MoNbTaW, AlCoCrFeNiTi, or CoCrFeMnNi. Conventional alloys used in gas turbine engines <NUM> include one or possibly two main elements with the addition of several other elements in relatively small amounts. Conversely, HEAs are formed from multiple principal elements in high concentrations and can be compositionally tailored to include self-lubrication and wear resistant properties at elevated temperatures.

Table <NUM> below illustrates an example composition for CoCrFeMnNi. A similar composition range can also be used for the MoNbTaW and AlCoCrFeNiTi.

In one example, the seals <NUM>, <NUM> are made through an additive manufacturing process from the HEA. Unlike conventional alloys, HEA are not typically formed directly from casting or ingot + wrought processes. In one example, the seals <NUM>, <NUM> are formed through a powder bed system with a computer controlled heat source, such as with a selective laser melting process or an electron beam melting process. With the powdered bed system, the heat source is applied to the powdered HEA forming a layer in a powdered bed to weld or melt the powdered HEA. Additional layers of powdered HEAs can be added after welding or melting existing layers to form the final shape of the seal <NUM>, <NUM>.

In another example, the seals <NUM>,<NUM> could be formed through a powder feed system with a computer controlled heat source, such as with a laser direct deposition process or a laser engineered net shaping ("LENS") process. The LENS process uses computer-controlled lasers to weld air-blown streams of powdered HEAs into the desired shape for the seals <NUM>, <NUM>. One feature of the LENS process is the ability to generate a seal with sufficient precision in a complex geometry without additional machining steps to achieve a finished seal.

The LENS process, as well as the other HEA forming processes discussed above, allow for the formation of complex geometries of the seals <NUM>, <NUM> with a large enough scale to form a circumferential ring on a radially outer side of the core air flow path C in the gas turbine engine <NUM>. This is an improvement over prior art designs, such as seals formed from a polycrystalline or single crystal nickel alloy, which are difficult to form in a complex shape with a diameter large enough to surround a core air flow path C in the gas turbine engine <NUM> and/or withstand elevated operating temperatures of the gas turbine engine <NUM>. Additionally, seals formed directly from cast feedstock may include a j oining-related discontinuity formed between opposite ends of the seal <NUM> which creates a possible leakage path through the seal <NUM> and can cause an increased amount of hot gases from the core air flow path C mixing with the cold fluid area <NUM> or another cold fluid area in the gas turbine engine <NUM>.

Another feature of the seal <NUM> formed from HEAs, such as MoNbTaW, is the formation of a solid lubricant between the seal <NUM>, <NUM> and a counterface. During operation of the gas turbine engine <NUM>, the seal <NUM>, <NUM> is in contact with a counterface at elevated temperatures and exhibits a fretting motion with low wear and low friction. The low wear and low friction between the seal <NUM> and the counterface is at least partially attributed to the formation of a metal oxide that forms the solid lubricant. The metal oxide can also transfer to the counterface and further reduce friction and heating associated with the frictional forces during operation of the gas turbine engine <NUM>.

Additionally, a low friction coefficient and high wear resistance of the seal <NUM> can also be obtained at low temperatures, such as during engine load fluctuations, and is at least partially attributed to the formation of a Ta-based tribofilm in the case of using MoNbTaW. However, other tribofilms can formed when using other HEAs. Although the above example is with respect to a specific HEA material, other HEA materials exhibit similar properties during both high and low temperature operations.

One feature of the seals <NUM>, <NUM> made from HEAs is an increased time interval between overhauls of the gas turbine engine <NUM> and a reduction in the number of parts needed to be replaced during an overhaul because of the improved sealing and wear characteristics of the seals <NUM>, <NUM>. Additionally, the low frictional performance of the seals <NUM>, <NUM> results in less wear on the counterface of the components which extends the life of the component and reduces the number of parts replaced during an overhaul.

<FIG> illustrates a method <NUM> of creating the seals <NUM>, <NUM>. The method includes providing (<NUM>) a powdered HEA, such as MoNbTaW, AlCoCrFeNiTi, or CoCrFeMnNi. The powdered HEA is formed (<NUM>) into the shape of the seal <NUM>, <NUM> through exposure to a heat source, such as a laser beam or an electron beam as described above. In one example, the powdered HEA is air blown while a computer controller laser welds the stream of powdered HEA into the desired shape of the seal <NUM>, <NUM>. Furthermore, the precision of the computer-controlled laser is sufficiently precise to allow the seals <NUM>, <NUM> to be formed without the need for additional machining of an exterior surface of the seal <NUM>, <NUM>, which reduces the number of steps to create the seal <NUM>, <NUM>.

Although the different non-limiting examples are illustrated as having specific components, the examples of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting examples in combination with features or components from any of the other non-limiting examples.

Claim 1:
A tribological and creep resistant system configured to operate at temperatures in excess of <NUM>, comprising
a seal body (<NUM>; <NUM>) extending between a leading edge (<NUM>; <NUM>) and a trailing edge (<NUM>; <NUM>) including a first component contact surface adjacent the leading edge (<NUM>; <NUM>) and a second component contact surface adjacent the trailing edge (<NUM>; <NUM>); and
a first component (<NUM>) engaging the first component contact surface on the leading edge (<NUM>) of the seal body (<NUM>) and a second component (<NUM>) engaging the second component contact surface on the trailing edge (<NUM>) of the seal body (<NUM>),
wherein the seal body (<NUM>; <NUM>) is formed from a high entropy alloy, and wherein the high entropy alloy includes one of MoNbTaW, AlCoCrFeNiTi, or CoCrFeMnNi.