High temperature, low friction, wear coating

Abstract

A method for applying a coating (122, 122A-122D) includes: providing a wt% mixture of at least 50.0 metallic binder precursor(s), 2.0 to 20.0 metallic solid lubricant, 2.0 to 10.0 CaF2, and no more than 1.0 BaF2, if any, optionally with hardener. The mixture is sprayed on a metallic substrate and may form a wear coting for a seal.

Description

HIGH TEMPERATURE, LOW FRICTION, WEAR COATINGCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Benefit is claimed of US Patent Application No. 63702091, filed October 1, 2024, entitled “High Temperature, Low Friction, Wear Coating”, and US Patent Application No. 63700677, filed September 28, 2024, entitled “Rotational Equipment Non-Contact Seal with Wear Coating”, the disclosures of which are incorporated by reference herein in their entireties as if set forth at length.BACKGROUND

[0002] This disclosure relates generally to rotational equipment and, more particularly, to a high temperature, low friction, wear resistant coating for aerospace applications.

[0003] Rotational equipment typically includes one or more seal assemblies for sealing gaps between rotors and stators. A typical seal assembly includes a contact seal with a seal element such as a knife edge seal that engages a seal land. Such a contact seal can generate a significant quantity of heat that can reduce efficiency of the rotational equipment as well as subject other components of the rotational equipment to high temperatures and internal stresses. To accommodate these high temperatures and stresses, certain components of the rotational equipment may be constructed from specialty high temperature materials.However, these materials can significantly increase manufacturing and servicing costs as well as mass of the rotational equipment. While non-contact seals have been developed in an effort to reduce heat within rotational equipment, there is still room for improvement to provide an improved non-contact seal.

[0004] Additionally, there is still room for improvement in contact seals and other wear surfaces.

[0005] The NASA PS series (plasma spray) of coatings featuring metallic binder matrix, a hardener, and solid lubricants. The binder matrix is an NiCr in the PS 100 and PS300 series, Ni-Co in the PS200 series and NiMoAl in the PS400 series. A hardener is glass in the PS 100 series, chrome carbide in the PS200 series, and chromium oxide in the PS300 and PS400 series. In the PS 100 series, the solid lubricant is a mixture of silver and calcium fluoride. In the PS200, PS300, and PS400 series, the solid lubricant is a mixture of silver and a calcium fluoride / barium fluoride eutectic.SUMMARY

[0006] One aspect of the disclosure involves an apparatus for rotational equipment, comprising a non-contact seal including a primary seal device, a secondary seal assembly and a support ring. The primary seal device includes a plurality of seal shoes, a seal base and a plurality of spring elements. The plurality of seal shoes are arranged end-to-end around an axis in an array, the plurality of seal shoes comprising a first seal shoe. The seal base circumscribes the array of the plurality of seal shoes, the plurality of spring elements respectively connecting and extending an associated said seal shoe and the seal base. The secondary seal assembly is configured to seal a gap between the seal base and the plurality of seal shoes. The secondary seal assembly comprises a secondary seal device contacting each of the plurality of seal shoes. The support ring is next to the plurality of seal shoes with the plurality of seal shoes located between the support ring and the secondary seal device. A first member of the non-contact seal comprises a substrate and a wear coating over the substrate. The wear coating or a layer thereof includes a binder matrix and a solid lubricant material within the binder matrix. The binder matrix comprises: one or more NiMoAl alloys; one or more MCrAlY alloys; one or more cobalt-based alloys; or combinations thereof. The solid lubricant material comprises CaF2 at an overall level of at least 2.0 weight percent. The solid lubricant material comprises a metallic solid lubricant at an overall level of at least 2.0 weight percent. The wear coating or layer thereof has no more than 1.0 weight percent BaF2, if any.

[0007] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the binder matrix comprises said one or more cobalt-based alloys. Said one or more cobalt based alloys may in various embodiments have Co as the largest by-weight content and Cr, Ni, or Mo as the second largest by-weight content. In various embodiments said second largest by-weight component may be at least 19.0 weight percent of the cobalt based alloy.

[0008] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the binder matrix comprises an alloy including nickel cobalt.

[0009] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the binder matrix comprises said one or more NiMoAl alloys.

[0010] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, wherein the binder matrix comprises said one or more MCrAlY alloys comprising nickel, cobalt, chromium, aluminum, tantalum and yttrium.

[0011] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the solid lubricant material comprises silver.

[0012] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the wear coating or a layer thereof has no more than 0.50 weight percent BaF2, if any.

[0013] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the solid lubricant material comprises silver as said metallic solid lubricant at an overall level of at least 2.0 weight percent.

[0014] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the solid lubricant material comprises copper as said metallic solid lubricant at an overall level of at least 2.0 weight percent.

[0015] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the solid lubricant material comprises molybdenum as said metallic solid lubricant at an overall level of at least 2.0 weight percent.

[0016] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the coating comprises: not more than an overall level of at least 10 (optionally 10 to 30) weight percent hardener, if any, within the binder matrix, said hardener selected from the group consisting of glass particles, chromium carbide, chromium oxide; and combinations thereof; and not more than 5.0% aggregate / total and 1.0% individually, additional phases.

[0017] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the wear coating includes said chromium oxide at an overall level of at least 10 (optionally 10 to 30) weight percent.

[0018] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively: the binder matrix comprises one of an alloy including nickel and chromium, an alloy including nickel and cobalt or an alloy including nickel, molybdenum and aluminum; and the solid lubricant material comprises at least one of silver, barium-fluoride or calciumfluoride.

[0019] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the wear coating further includes a hardener within the binder matrix, and the hardener comprises one of glass particles, chromium carbide or chromium oxide.

[0020] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively: the binder matrix comprises an alloy including nickel, cobalt, chromium, aluminum, tantalum and yttrium; and the solid lubricant material comprises at least one of copper, molybdenum, barium-fluoride or calcium-fluoride.

[0021] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the first member comprises the support ring, and the wear coating is operable to contact the plurality of seal shoes.

[0022] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, wherein the first member comprises the first seal shoe, and the wear coating is operable to contact one of the support ring or the secondary seal device.

[0023] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the first member comprises the secondary seal device, and the wear coating is operable to contact the plurality of seal shoes.

[0024] A further aspect of the disclosure involves an apparatus for rotational equipment, comprising: a non-contact seal including a primary seal device, a secondary seal assembly and a support ring. The primary seal device includes a plurality of seal shoes, a seal base and a plurality of spring elements, the plurality of seal shoes arranged end-to-end around an axis in an array, the plurality of seal shoes comprising a first seal shoe, the seal base circumscribing the array of the plurality of seal shoes, the plurality of spring elements comprising a first spring element, and the first spring element connecting and extending between the first seal shoe and the seal base. The secondary seal assembly is configured to seal a gap between the seal base and the plurality of seal shoes, and the secondary seal assembly comprising a secondary seal device axially contacting each of the plurality of seal shoes. The support ring is axially next to the plurality of seal shoes with the plurality of seal shoes located axially between the support ring and the secondary seal device. At least one of the first seal shoe, the secondary seal device or the support ring comprises a binder matrix, a solid lubricant material and a hardener. The binder matrix comprises: one or more NiMoAl alloys; one or more MCrAlY alloys; one or more cobalt-based alloys; or combinations thereof. The solid lubricant material within the binder matrix comprises at least overall 2.0 weight percent metallic solid lubricant and at least overall 2.0 weight percent calciumfluoride and no more than 1.0 overall weight percent barium-fluoride, if any. The hardener within the binder matrix comprises one of glass particles, chromium carbide or chromium oxide.

[0025] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the binder matrix comprises said one or more NiMoAl alloys.

[0026] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the metallic solid lubricant material comprises silver.

[0027] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the metallic solid lubricant material comprises silver as said metallic solid lubricant at an overall level of at least 2.0 weight percent.

[0028] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the overall weight percent barium-fluoride, if any is not more than 0.50 weight percent.

[0029] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the hardener includes said chromium oxide at an overall level of at least 10, optionally 10 to 30, weight percent.

[0030] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, said at least one of the first seal shoe, the secondary seal device or the support ring comprising said binder matrix, solid lubricant material, and hardener as a coating on a metallic substrate.

[0031] A further aspect of the disclosure involves an apparatus for rotational equipment, comprising a non-contact seal including a primary seal device, a secondary seal assembly and a support ring. The primary seal device includes a plurality of seal shoes, a seal base and a plurality of spring elements, the plurality of seal shoes arranged end-to-end around an axis in an array, the plurality of seal shoes comprising a first seal shoe, the seal base circumscribing the array of the plurality of seal shoes, the plurality of spring elements comprising a first spring element, and the first spring element connecting and extending between the first seal shoe and the seal base. The secondary seal assembly is configured to seal a gap between the seal base and the plurality of seal shoes, and the secondary seal assembly comprises a secondary seal device axially contacting each of the plurality of seal shoes. The support ring is axially next to the plurality of seal shoes with the plurality of seal shoes located axially between the support ring and the secondary seal device. At least one of the first seal shoe, the secondary seal device or the support ring comprising a binder matrix and a solid lubricant material. The binder matrix comprises an alloy including nickel, cobalt, chromium, aluminum, tantalum and yttrium. The solid lubricant material within the binder matrix comprises copper, molybdenum, and calcium-fluoride each at at least 2.0 overall weight percent with no more than 1.0 overall weight percent barium fluoride.

[0032] A further aspect of the disclosure involves a method for applying a coating, the method comprising: providing a wt% mixture of at least 50.0 metallic binder precursor(s), 2.0to 20.0 metallic solid lubricant 2.0 to 10.0 CaF2, and no more than 1.0 BaF2, if any; and spraying the mixture on a metallic substrate.

[0033] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the coating has an at least local thickness of 125 micrometers to 800 micrometers, more particularly, 150 micrometers to 400 micrometers, or 150 micrometers to 300 micrometers.

[0034] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the coating is directly atop the substrate alloy (e.g., Ni or Co-based alloy (e.g., superalloy)).

[0035] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the metallic solid lubricant is selected from the group consisting of: Ag; Cu; Mo; and combinations thereof.

[0036] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the metallic solid lubricant comprises at overall wt. %: 2.0 to 5.0 Ag.

[0037] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the metallic solid lubricant comprises at overall wt. %: 2.0 to 5.0 Cu.

[0038] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the mixture further comprises a hardener comprising: one or more carbides; one or more ceramics; or a combination thereof.

[0039] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the mixture further comprises: CnCF powder.

[0040] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the spraying is air plasma spray (APS), HVOF, HVAF, or cold spray.

[0041] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the spraying is HVOF spraying.

[0042] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the metallic binder precursor(s) comprise: MCrAlY.

[0043] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the MCrAlY is a NiCoCrAlY or CoNiCrAlY.

[0044] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the mixture has a combined content said Mo and the Co of said MCrAlY of 12.5 weight percent to 45.0 weight percent.

[0045] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the MCrAlY is a NiCoCrAlTaY.

[0046] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the NiCoCrAlTaY comprises by weight percent: Ni as a largest by weight constituent; 20.0 to 26.0 Co; 18.0 to 23.0 Cr; 6.0 to 11.0 Al; 2.0 to 6.0 Ta; and 0.3 to 0.9 Y.

[0047] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, one or more of: the MCrAlY is 50 to 90 weight percent of the mixture; the mixture further includes 0 to 30 weight percent chromium oxide hardener, if any; and the combined metallic solid lubricant, CaF2, and BaF2, if any, is 10 to 30 weigh percent.

[0048] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, one or more of: the MCrAlY is 70 to 90 weight percent of the mixture; the mixture further includes 0 to 10 weight percent chromium oxide hardener, if any; and the combined metallic solid lubricant, CaF2, and BaF2, if any, is 10 to 30 weigh percent.

[0049] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, one or more of: the MCrAlY is 50 to 70 weight percent of the mixture; the mixture further includes 10 to 30 weight percent chromium oxide hardener; the combined metallic solid lubricant, CaF2, and BaF2, if any, is 10 to 30 weigh percent; and the mixture includes no more than 5.0 weight percent other total.

[0050] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the metallic binder precursor(s) comprises CoCr alloy.

[0051] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the CoCr alloy comprises: <2.0 C; <2.5 Mn; <2.5 Si; <0.1 P; <0.1 S; 18.0- 35.0Cr; <30.0 Ni; <8.0 Mo; <16.0 W; <4.0 Fe; and balance Co and no more than 7.0 each other element, if any, individually and 15.0 all other elements total.

[0052] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the CoCr alloy comprises: <2.0 C; <2.5 Mn; <2.5 Si; <0.1 P; <0.1 S; 18.0- 35.0Cr; <30.0 Ni; <8.0 Mo; <16.0 W; <4.0 Fe; and balance Co and no more than 1.0 each other element, if any, individually and 5.0 all other elements total.

[0053] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the CoCr alloy may have Co as the largest by weight constituent and Cr as the second largest.

[0054] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the metallic binder precursor(s) comprises NiMoAl.

[0055] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the NiMoAl comprises by weigh percent: 2.5 to 7.5 Mo; 2.5 to 7.5 Al; and Ni balance plus impurities,

[0056] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, one or more of: the NiMoAl is 60 to 80 weight percent of the mixture; the mixture further includes 10 to 30 weight percent chromium oxide hardener; and the combined metallic solid lubricant, CaF2, and BaF2, if any, is 10 to 30 weigh percent.

[0057] A further aspect of the disclosure involves an article comprising: a metallic substrate; and a wear coating. The wear coating or a layer thereof includes a binder matrix and a solid lubricant material within the binder matrix. The binder matrix comprises: one or more NiMoAl alloys; one or more MCrAlY alloys; one or more cobalt-based alloys; or combinations thereof. The solid lubricant material comprises CaF2 at an overall level of at least 2.0 weight percent. The solid lubricant material comprises a metallic solid lubricant at an overall level of at least 2.0 weight percent. The wear coating or a layer thereof has no more than 1.0 weight percent BaF2, if any.

[0058] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the wear coating or a layer thereof further comprises a hardener comprising: one or more carbides; one or more ceramics; or a combination thereof.

[0059] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the wear coating or layer thickness is 125 micrometers to 800 micrometers, more particularly, 150 micrometers to 400 micrometers, or 150 micrometers to 300 micrometers.

[0060] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the coating is directly atop the substrate alloy (e.g., Ni or Co-based alloy (e.g., superalloy)).

[0061] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the wear coating forms a counterface for a seal ring.

[0062] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the substrate forms a groove accommodating a seal ring and the wear coating is on a face of the groove facing the seal ring.

[0063] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the binder matrix comprises said one or more NiMoAl alloys.

[0064] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the metal solid lubricant comprises silver.

[0065] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the substrate forms a disk bore and the wear coating is on an inner diameter face of the disk bore.

[0066] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the substrate forms a component of a non-contact seal.

[0067] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the substrate forms a component of a non-contact seal.

[0068] The present disclosure may include any one or more of the individual features disclosed above and / or below alone or in any combination thereof.

[0069] The foregoing features and the operation of the invention will become more apparent in light of the following description and the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0070] FIG. 1 is a partial side sectional illustration of an assembly for rotational equipment with a support ring formed integral with a seal carrier.

[0071] FIG. 2 is a perspective sectional illustration of a portion of the rotational equipment assembly.

[0072] FIG. 3 is a partial side sectional illustration of the rotational equipment assembly with the support ring discrete from the seal carrier.

[0073] FIG. 4 is a perspective illustration of a primary seal device.

[0074] FIG. 5 is a partial side sectional illustration of the primary seal device from a perspective taken along section line 5-5 in FIG. 6.

[0075] FIG. 6 is a partial cross-sectional illustration of the primary seal device.

[0076] FIG. 7 is a partial side sectional illustration of the rotational equipment assembly at an interface between a seal shoe and the support ring.

[0077] FIG. 8 is a partial side sectional illustration of the rotational equipment assembly at an interface between secondary seal devices and the seal shoe.

[0078] FIG. 9 is a partial side schematic illustration of a gas turbine engine with which the rotational equipment assembly may be included.

[0079] FIG. 10 is an enlarged central longitudinal sectional view of an intra-rotor seal system.

[0080] FIG. 11 is an enlarged central longitudinal sectional view of a first static structure seal system.

[0081] FIG. 12 is an enlarged central longitudinal sectional view of a second static structure seal system.

[0082] FIG. 13 is an enlarged central longitudinal sectional view of a third static structure seal system.

[0083] FIG. 14 is an enlarged central longitudinal sectional view of a fourth static structure seal system.

[0084] FIG. 15 is a schematic sectional view of a coating.DETAILED DESCRIPTION

[0085] In several examples, a beneficial modification of a baseline lubricious wear coating (or coating feedstock powder) may be achieved by removing barium fluoride solid lubricant therefrom. To at least partially preserve the baseline lubricity, this may be at least partially replaced with additional calcium fluoride in examples involving baseline mixtures of barium fluoride and calcium fluoride.

[0086] Other examples may involve modifying a baseline relatively non-lubricious coating material by adding calcium fluoride and a metallic solid lubricant substantially in the absence of barium fluoride. Example metallic solid lubricants include silver, copper, molybdenum and combinations thereof.

[0087] Thus, as discussed further below, in one example, a baseline NiMoAl-based (NiMoAl as a binder matrix) lubricious hard coating such as a PS400 coating is modified by replacing the barium fluoride with an equal amount of calcium fluoride. This has the effect of essentially doubling the weight percent of calcium fluoride from 2.5% to 5%.

[0088] In a second group of examples, similar modifications may be applied to coatings having MCrAlY (e.g., namely, an NiCoCrAlTaY) binder matrix. In MCrAlY, M stands for Ni, Co, Fe or combination of two or three of the three (and the Cr, Al, and Y are additional elemental contents). However typical commercially MCrAlY used as bondcoats have little, if any, Fe (such as NiCrAlY, NiCoCrAlY and CoNiCrAlY with not more than 5 weight percent Fe, if any). Common intentional additions include small amounts of Si, Hf, and Zr.

[0089] A third group of examples may involve modifying a baseline cobalt-based alloy with the addition of essentially barium-free lubricant such as a combination of a metallic lubricant and calcium fluoride. Example cobalt-based alloys may in various embodiments have Co as the largest by-weight content and Cr, Ni, or Mo as the second largest by-weight content (e.g., a CoCr or CoCrNi alloy, e.g., a CoCrNiW alloy, or a CoMoCr alloy). Example metals include silver, copper, and molybdenum combined with calcium fluoride as solid lubricants.

[0090] The use of such essentially barium-free materials may offer near-equivalent performance at substantially reduced cost.

[0091] As is discussed further below, examples of the cobalt alloy-based or NiMoAl-based coating may have a notably lower solid lubricant content than the MCrAlY -based coating.

[0092] As noted above, example barium fluoride, if any, in the thermal spray feedstock is low. Distinguished from prior art levels of 2.5% by weight, an example is not more than 1.0% by weight. Thus, in general in examples below, the powder feedstock mixture may have, inweight percent: at least 50.0 metallic binder precursor(s); 2.0 to 20.0 metallic solid lubricant; 2.0 to 10.0 CaF2; and no more than 1.0 BaF2, if any. More particularly, BaF2 may be not more than 0.75% by weight or 0.50% by weight or 0.25% by weight or impurity levels. This is an overall weight percent in the feedstock not a percentage of the solid lubricant. With relatively small differential species attrition expected, this may also be an overall content in the coating or coating layer in a multi-layer coating. Similarly, example alternative lower limits on metallic solid lubricant are 2.5 or 4.0 weight percent and alternative upper limits are 18 or 15 weight percent in any combination.

[0093] Example coating or layer thickness is 125 micrometers to 800 micrometers, more particularly, 150 micrometers to 400 micrometers, or 150 micrometers to 300 micrometers.

[0094] Candidates for the solid lubricant metal include one or more of silver, copper, and molybdenum. In particular, the text discussion and tables below offer several examples of combinations.

[0095] Example NiMoAl as a matrix-former has, by weight percent, 5 Mo and 5.5 Al, balance Ni, more broadly 4.0-6.0 Mo and 4.0-7.0 Al, balance Ni. Example Ni may be at least 85.0 weight percent. There may be commercial or inevitable impurities said balance.Example impurities and minor additional intentional alloyants, if any, may be up to 5.0 weigh percent total and 2.0 weight percent individually. More narrowly limits on said total and individual numbers in any combination therewith or with each other may be totals of 3.0, 2.0, and 1.0 weight percent and individual numbers of 1.5, 1.0, and 0.5 weight percent.

[0096] The NiMoAl is mixed with solid lubricant (i.e., calcium fluoride and metallic solid lubricant(s) discussed above) and hardener for the powder blend spray feedstock.

[0097] Example metallic solid lubricants for use with NiMoAl include silver, copper, molybdenum and combinations thereof. Example range is 40-60 weight percent CaF2 and 40- 60 weight percent one or combined Ag, Cu, Mo. In general, the presence of Mo in the NiMoAl may favor having little to no Mo solid lubricant relative to coatings having low-Mo MCrAlY binder. Thus, the Mo may be a relatively small fraction if any of the metallic solid lubricant (e.g., not more than 25.0 weight percent). Thus, an example nominal solid lubricant is 50 weight percent CaF2 and 50 weight percent one or combined Ag and Cu. An alternative range is 40-60 weight percent CaF2 and 40-60 weight percent one or combined Ag and Cu. There may be commercial or inevitable impurities in such feedstock.

[0098] Example solid lubricant total in the mixture is 10.0 weight percent, more broadly 7.5 to 12.5 with alternative lower end limits of 5.0 and 10.0 and alternative upper limits of 15.0,20.0, and 30.0. However, the presence of hardener (discussed below) may dilute matrix content and favor the lower end of such ranges to preserve matrix content / function.

[0099] Example hardener total in mixture is 20 weight percent, more broadly 10.0 to 30.0, with alternative lower limits of 15.0 and 17.5 and alternative upper limits of 25.0 and 22.5 in any combination. As noted above, the example hardener is chromium oxide (chromia / C Oa). Other hardener variations are shown in Table III below. The hardeners may include ceramics (e.g., oxides), or carbides, or combinations within or across such groups. Particularly notable are chromium oxide and chromium carbide. Additional oxides include titanium oxide (titania / TiO2) and aluminum oxide (alumina / AI2O3). Titanium may be particularly useful as a secondary oxide to improve toughness and fracture resistance at a small cost in hardness.Similarly, addition of nickel chrome to a carbide may reduce hardness but improve toughness and fracture resistance.

[0100] In various examples, the mixture / blend may be said amounts of solid lubricant, hardener (chromia), balance said NiMoAl matrix precursor / former. As noted above, with relatively small differential species attrition expected, this may also be an overall content in the coating or coating layer in a multi-layer coating. In variations, there may be commercial or inevitable impurities said overall balance. Example impurities and minor additional intentional alloyants, if any, may be (as a content of the total mixture or coating / layer) up to 5.0 weigh percent total and 2.0 weight percent individually. More narrowly limits on said total and individual numbers in any combination therewith or with each other may be totals of 3.0, 2.0, and 1.0 weight percent and individual numbers of 1.5, 1.0, and 0.5 weight percent.

[0101] Example MCrAlY compositions are given in Table I below. Two baseline coating compositions using such MCrAlY differ from each other in one having chromia hardener. The nominal hardener free-composition is 80 weight percent MCrAlY and 20 weight percent solid lubricant. The nominal second composition is 60 weight percent MCrAlY, 20 weight percent chromia hardener, and 20 weight percent solid lubricant. Thus, their modified variants may have an example up to 30 weight percent chromia hardener or up to 20 weight percent. Compositions more like the first may have up to 10 weight percent chromia hardener or up to 5.0 weight percent. Compositions more 60-like the second may have 10 to 30 weight percent chromia hardener with an alternate lower limit of 15 and upper limit of 25 in any combination. Example MCrAlY have 63 to 71 wt% Ni + Co.

[0102] Table I lists several examples. Example 1 is based on measured composition of one particular NiCoCrAlTY. Example 2 is based upon a published composition of similarNiCoCrAlY including both Ta-containing and non-Ti-containing variants. Example 3 is based upon published composition for a particular NiCrAlY lacking cobalt. Example 4 is based on the published composition for a particular CoNiCrAlY. Example 5 is based on the public composition of a particular CoCrAlY.

[0103] In further variations on the Table I ranges, Y content may be 0.4 to 0.8, an Hf content may be up to 1.0 or 0.1 to 0.05, a Si content may be up to 1.0 or 0.1 to 0.07. A total of further “other” may be up to 2.0 or 1.0. Within said “other”, further narrowing may involve up to 0.030 or 0.020 C, up to 0.020 or 0.010 P, up to 0.020 or 0.010 S, up to 0.01 or 0.0025 Pb, up to 0.001 or 0.0001 Bi, up to 0.050 or 0.010 N. Among other intentional elements that may exceed said other are up to moderate quantities of a combination of W, Ta, Mo, for example up to 5.0 combined or up to 4.0 and / or up to moderate quantities of Zr, for example up to 1.0.

[0104] The Ex. 1 and Ex.2 CoNiCrAlY may offer excellent high temperature oxidation hot corrosion resistance. The Ex. 3 NiCoCrAlY may offer high temperature strength and hardness, and high temperature wear resistance.

[0105] Example metallic solid lubricants for use with MCrAlY include silver, copper, molybdenum and combinations thereof. Example range is 40-60 weight percent CaF2 and 40- 60 weight percent one or combined Ag, Cu, Mo. In general, the lack of Mo in the MCrAlY may favor having more Mo solid lubricant relative to coatings having NiMoAl binder. And, the Mo may be biased toward substitution for CaF2. Thus, however, the Mo may still be a relatively small fraction if any of the metallic solid lubricant (e.g., not more than 50.0 weight percent). Thus, an example nominal solid lubricant is 25 weight percent CaF2, 25 weight percent Mo, and 50 weight percent one or combined Ag and Cu. An alternative range is 15- 35 weight percent CaF2, 15 weight percent Mo, and 40-60 weight percent one or combined Ag and Cu. There may be commercial or inevitable impurities in such feedstock.

[0106] Example CoCr (notably including CoCrNiWC) include a number of Tribaloy® and Stellite® alloys such as Tribaloy® T-800 Co-Mo-Cr-Si intermetallic, Stellite® 6 Co-Cr, and Stellite® 31 Co-Cr-Ni alloy all of Kennametal Inc., Latrobe Pennsylvania and Mar-M alloys .Examples are given in Table II below. In the ranges at the end of said table, alternative ranges may replace the double dagger option with an impurities only option or with an impurities level for blank cells while maintaining the double dagger otherwise. Yet, alternative double dagger limitations are 2.0 weight percent combined and 0.50 weight percent individual or 7.0 individually and 15.0 total. Example net feedstocks and coatings lack hardener.

[0107] Example solid lubricant total in the mixture is 10.0 weight percent, more broadly 7.5 to 12.5 with alternative lower end limits of 5.0 and alternative upper limits of 15.0 and 20.0. Relative hardness particularly with carbide-containing variants may favor having little to no Mo solid lubricant relative to coatings having low-Mo MCrAlY binder. Thus, the Mo may be a relatively small fraction if any of the metallic solid lubricant (e.g., not more than 25.0 weight percent). Thus, an example nominal solid lubricant is 50 weight percent CaF2 and 50 weight percent one or combined Ag and Cu. An alternative range is 40-60 weight percent CaF2 and 40-60 weight percent one or combined Ag and Cu. There may be commercial or inevitable impurities in such feedstock.Table I MCrAlY Binder Feedstock / Matrix Alloys (weight %)Table II Co-Based Binder Feedstock / Matrix Alloys (weight %)Table II (Continued)Table II (Continued)tt < 5.0 other elements total; < 1.0 other elements individually (both inclusive of elements for which there is a blank cell)Table III Hardener Compositions

[0108] FIG. 1 illustrates an assembly 20 for rotational equipment such as a powerplant for an aircraft. The aircraft may be an airplane, a helicopter, a drone (e.g., an unmanned aerial vehicle (UAV)) or any other manned or unmanned aerial vehicle or system. The powerplant may be configured as, or otherwise included as part of, a propulsion system for the aircraft. The powerplant, for example, may be a turbofan engine, a turbojet engine, a turboprop engine, a turboshaft engine, or any other type of combustion engine configured to generate thrust and / or drive rotation of a ducted or open propulsor rotor which is configured to generate thrust. The powerplant may alternatively (or also) be configured as, or otherwise included as part of, a power generation system for the aircraft. The powerplant, for example, may be an auxiliary power unit (APU) or any other type of combustion engine configured to mechanically power operation of an electrical generator. The present disclosure, however, is not limited to such exemplary combustion engine powerplants. The rotational equipment assembly 20, for example, may alternatively be included in an electric machine, an industrial gas turbine engine, or any other apparatus in which a seal is provided between a stationary structure and a rotating structure (e.g., a rotor) in both aircraft applications as well as nonaircraft applications.

[0109] The rotational equipment assembly 20 of FIG. 1 includes a stationary structure 24, a rotating structure 26 and a non-contact seal 28. The non-contact seal 28 is mounted with the stationary structure 24 and configured to substantially seal an annular gap between the stationary structure 24 and the rotating structure 26 as described below in further detail.

[0110] The stationary structure 24 includes a seal carrier 30. This seal carrier 30 may be a discrete, unitary annular body. Alternatively, the seal carrier 30 may be configured with another component / portion of the stationary structure 24. The seal carrier 30 has a seal carrier inner surface 32. This seal carrier inner surface 32 may be substantially cylindrical. The seal carrier inner surface 32 extends circumferentially about (e.g., completely around) and faces towards an axis 33. Briefly, this axis 33 may be a centerline axis of the rotational equipment assembly 20 and / or one or more of its members 24, 26 and / or 28. The axis 33 may also or alternatively be a rotational axis of the rotating structure 26. The seal carrier inner surface 32 of FIG. 1 at least partially forms a bore in the stationary structure 24. This bore is sized to receive the non-contact seal 28, which non-contact seal 28 may be fixedly attached to the seal carrier 30 by, for example, a press fit connection between the non-contact seal 28 and the seal carrier inner surface 32. The non-contact seal 28, of course, may also or alternativelybe fixedly attached to the seal carrier 30 using one or more other mounting techniques / devices.

[0111] The rotating structure 26 includes a rotating seal land 34. This rotating seal land 34 may be a discrete, unitary annular body. For example, the rotating seal land 34 may be mounted to a shaft of the rotating structure 26. Alternatively, the rotating seal land 34 may be configured with another component / portion of the rotating structure 26. For example, the rotating seal land 34 may be an integral part of a shaft of the rotating structure 26, or another component mounted to the shaft.

[0112] The rotating seal land 34 of FIG. 1 has a radial outer seal land surface 36. This outer seal land surface 36 may be substantially cylindrical. The outer seal land surface 36 extends circumferentially about (e.g., completely around) and faces away from the axis 33. The outer seal land surface 36 is configured to face towards and may be axially aligned with the seal carrier inner surface 32. While FIG. 1 illustrates the outer seal land surface 36 and the seal carrier inner surface 32 with approximately equal axial lengths along the axis 33, the outer seal land surface 36 may alternatively be longer or shorter than the seal carrier inner surface 32 in other embodiments.

[0113] The non-contact seal 28 includes a primary seal device 38 and one or more secondary seal devices 40. The non-contact seal 28 also includes one or more additional components for positioning, supporting and / or mounting one or more of the seal devices with the stationary structure 24. The non-contact seal 28 of FIG. 1, for example, includes a seal ring 42 and a support ring 43. The seal ring 42 is configured to position, support and / or mount the secondary seal devices 40 relative to the primary seal device 38. At least (or only) the one or more secondary seal devices 40 and the seal ring 42 of FIG. 1 collectively provide the noncontact seal 28 with a secondary seal assembly 44. The seal ring 42 may also be configured to axially position and / or support an axial first side 46 of a seal base 48 of the primary seal device 38 relative to the stationary structure 24. The support ring 43, on the other hand, is configured to axially position and / or support an axial second side 50 of the seal base 48 of the primary seal device 38 relative to the stationary structure 24. This support ring 43 extends axially along the axis 33 between an axial first side 52 of the support ring 43 and an axial second side 54 of the support ring 43. The support ring 43 extends circumferentially about (e.g., completely around) the axis 33.

[0114] The support ring 43 of FIG. 1 is permanently connected to (e.g., formed integral with, bonded to, etc.) the stationary structure 24 and its seal carrier 30. The support ring 43, forexample, may be formed with the seal carrier 30 in a single monolithic body 56. Herein, the term “monolithic” may describe a body which is formed as a unitary structure. The support ring 43 and the seal carrier 30, for example, may be collectively cast, machined, additively manufactured and / or otherwise formed together to provide the monolithic body 56. By contrast, a non-monolithic body includes a plurality of discretely formed elements which are mechanically fastened and / or otherwise removably attached together following their formation. The support ring 43 of FIG. 1 is configured as an annular and / or castellated shoulder of the stationary structure 24 (see also FIG. 2), which annular and / or castellated shoulder of the stationary structure 24 projects radially inward from the seal carrier 30 to a distal inner end 58.

[0115] Referring to FIG. 3, the support ring 43 may alternatively be configured as a discrete element from the stationary structure 24 and its seal carrier 30. The support ring 43 of FIG. 3, for example, is fixedly attached to the seal carrier 30 by, for example, a press fit connection between the support ring 43 and the seal carrier inner surface 32. The support ring 43, of course, may also or alternatively be fixedly attached to the seal carrier 30 using one or more other techniques / devices. Here, the support ring 43 is configured as an annular scalloped support plate mated with (e.g., nested with) the seal carrier 30.

[0116] Referring to FIG. 4 the primary seal device 38 is configured as an annular seal device such as, but not limited to, a non-contact hydrostatic seal device. The primary seal device 38 includes the seal base 48, a plurality of seal shoes 60 and a plurality of spring elements 62 (see also FIGS. 5 and 6).

[0117] The seal base 48 may be configured as an annular full hoop body. The seal base 48 of FIG. 4 extends circumferentially about (e.g., completely around) the axis 33. The seal base 48 is configured to extend circumferentially around and thereby circumscribe and support the seal shoes 60 as well as the spring elements 62. Referring to FIG. 5, the seal base 48 extends axially along the axis 33 from its seal base first side 46 to its seal base second side 50. The seal base 48 extends radially between a radial inner side 64 of the seal base 48 and a radial outer side 66 of the seal base 48. The seal base outer side 66 of FIG. 1 (see also FIG. 3) radially engages (e.g., is press fit against or otherwise contacts) the stationary structure 24 and its inner surface 32, where the stationary structure 24 and its seal carrier 30 extend circumferentially about (e.g., circumscribe) the seal base 48.

[0118] Referring to FIG. 4, the seal shoes 60 may be configured as arcuate bodies and are arranged end-to-end circumferentially around the axis 33 in an annular array. Each seal shoe60, for example, is arranged circumferentially between and next to a pair of circumferentially neighboring (e.g., adjacent) seal shoes 60. The annular array of the seal shoes 60 extends circumferentially about (e.g., completely around) the axis 33, thereby forming an inner bore at a radial inner side 68 of the primary seal device 38. As best seen in FIG. 1, the inner bore is sized to receive the rotating seal land 34, where the rotating structure 26 projects axially through (or into) the inner bore formed by the seal shoes 60.

[0119] Referring to FIG. 6, each of the seal shoes 60 extends radially from the primary seal device inner side 68 of the to a radial outer side 70 of that seal shoe 60. Each of the seal shoes 60 extends circumferentially about the axis 33 between opposing circumferential first and second ends 72 and 74 of that seal shoe 60. Referring to FIG. 5, each of the seal shoes 60 extends axially along the axis 33 between an axial first end 76 of the seal shoe 60 and an axial second end 78 of the seal shoe 60. The axial seal shoe first end 76 may be an upstream and / or high pressure end relative, for example, to flow of leakage fluid across the primary seal device 38. The axial seal shoe first end 76 is axially offset / spaced from the seal base first side 46. The axial seal shoe second end 78 may be a downstream and / or low pressure end relative, for example, to the flow of leakage fluid across the primary seal device 38. The axial seal shoe second end 78 may be generally axially aligned with the seal base second side 50. The seal shoes 60 of the present disclosure, however, are not limited to such exemplary relationships.

[0120] Each of the seal shoes 60 includes a seal shoe base 80 and one or more seal shoe protrusions 82A-D (generally referred to as “82”); e.g., inner projections such as rails and / or teeth. The seal shoe base 80 is disposed at (e.g., on, adjacent or proximate) the seal shoe outer side 70. The seal shoe base 80 of FIG. 6, for example, includes a (e.g., arcuate) base outer surface 84 at the seal shoe outer side 70. Referring to FIG. 5, the seal shoe base 80 extends radially between the base outer surface 84 and one or more (e.g., arcuate) base inner surfaces 86. Each of these base inner surfaces 86 may be an arcuate surface. Referring to FIG. 6, the seal shoe base 80 extends circumferentially about the axis 33 between the seal shoe first end 72 and the seal shoe second end 74. The seal shoe base 80 includes a first end surface 88 at the seal shoe first end 72 and a second end surface 90 at the seal shoe second end 74. Each of the end surfaces 88 and 90 may be a flat planar surface. More particularly, each of the end surfaces 88, 90 may have a straight sectional geometry when viewed, for example, in a reference plane perpendicular to the axis 33; e.g., the plane of FIG. 6. Referring to FIG. 5, theseal shoe base 80 extends axially between the seal shoe first end 76 and the seal shoe second end 78.

[0121] The seal shoe base 80 includes a (e.g., arcuate) side surface 92 generally at or near the seal shoe first end 76. In the array, these side surfaces 92 collectively form a generally annular, but circumferentially segmented, side surface configured for sealingly engaging with (e.g., contacting) the secondary seal devices 40 as shown in FIG. 1. The seal shoes 60 of the present disclosure, however, are not limited to the foregoing exemplary configuration.

[0122] Referring to FIG. 5, the seal shoe protrusions 82 are arranged at discrete axial locations along the axis 33 and the seal shoe base 80. Each pair of axially adjacent / neighboring protrusions 82 may thereby be axially separated by an (e.g., arcuate) interprotrusion gap. The seal shoe protrusions 82 of FIG. 5 are configured parallel to one another.

[0123] The seal shoe protrusions 82 may be arranged in a concentrated grouping 94. This grouping 94 may be asymmetrically arranged axially along the axis 33 between the seal shoe first end 76 and the seal shoe second end 78. For example, an axial center 96 (e.g., midpoint) of the grouping 94 of the seal shoe protrusions 82 in FIG. 5 is arranged closer to the seal shoe first end 76 than the seal shoe second end 78. More particularly, the axial center 96 is disposed axially between the seal shoe first end 76 and an axial center 98 (e.g., midpoint) of the respective seal shoe 60 and its seal shoe base 80. Thus, one or more or each of the seal shoe protrusions 82A-C (e.g., protrusions) may be located axially along the axis 33 between the seal shoe first end 76 and the axial center 98. The seal shoe protrusions 82 of the present disclosure, however, are not limited to the foregoing exemplary asymmetric configuration.

[0124] The seal shoe protrusions 82 are connected to (e.g., formed integral with or otherwise attached to) the seal shoe base 80. Each of the seal shoe protrusions 82 projects radially inwards from the seal shoe base 80 and its base inner surfaces 86 to a radial distal protrusion end. Each of the seal shoe protrusions 82 has a protrusion inner surface 100A-D (generally referred to as “100”) at the distal protrusion end. One or more or each of the protrusion inner surfaces 100 may also be at the inner side 68 of the primary seal device 38. Each protrusion inner surface 100 may be an arcuate surface. Each protrusion inner surface 100, for example, may have an arcuate sectional geometry when viewed, for example, in a reference plane perpendicular to the axis 33; e.g., the plane of FIG. 6. The protrusion inner surfaces 100 are configured to be arranged in close proximity with (but not touch) and thereby sealingly mate with the outer seal land surface 36 in a non-contact manner (see FIG. 1), where the rotating structure 26 projects axially through (or into) the inner bore formed by the seal shoes 60.

[0125] Each of the seal shoe protrusions 82 extends axially between axially opposing projection end surfaces 102. Each of these end surfaces 102 extends radially between and may be contiguous with a respective one of the projection inner surfaces 100 and a respective one of the base inner surfaces 86.

[0126] Each of the seal shoe protrusions 82 of FIG. 5 has the same radial height. One or more of the seal shoe protrusions 82, however, may alternatively have a different radial height than at least another one of the seal shoe protrusions 82.

[0127] Referring to FIG. 4, the spring elements 62 are arranged circumferentially about the axis 33 in an annular array. Referring to FIGS. 5 and 6, the spring elements 62 are also arranged (e.g., radially) between the seal shoes 60 and the seal base 48. Each of the spring elements 62 is configured to moveably and resiliently connect a respective one of the seal shoes 60 to the seal base 48.

[0128] The spring element 62 of FIG. 6 includes inner and outer mounts 104 and 106 (e.g., inner and outer radial fingers / projections) and one or more spring beams 108A and 108B (generally referred to as “108”). The inner mount 104 may be directly or indirectly connected to (e.g., formed integral with or otherwise attached to) a respective one of the seal shoes 60 and its seal shoe base 80 at the circumferential seal shoe first end 72, where the opposing circumferential seal shoe second end 74 is free floating; e.g., the seal shoe 60 is cantilevered from the inner mount 104. The inner mount 104 projects radially outward from the respective seal shoe 60 and its seal shoe base 80.

[0129] The outer mount 106 may be directly or indirectly connected to the seal base 48, and is generally circumferentially aligned with or near the circumferential seal shoe second end 74. The outer mount 106 is therefore disposed a circumferential distance from the inner mount 104. The outer mount 106 projects radially inward from the seal base 48.

[0130] The spring beams 108 are configured as resilient, biasing members of the primary seal device 38. The spring beams 108 of FIG. 6, for example, are configured as cantilevered-leaf springs. These spring beams 108 may be radially stacked and spaced apart from one another so as to form a four bar linkage with the inner mount 104 and the outer mount 106. More particularly, each of the spring beams 108 may be directly or indirectly connected to the inner mount 104 and the outer mount 106. Each of the spring beams 108 extends laterally (e.g., circumferentially or tangentially) between and to the inner mount 104 and the outer mount 106. The spring beams 108 of FIG. 6 may thereby laterally overlap a major circumferential portion (e.g., -65-95%) of the respective seal shoe 60.

[0131] During operation of the primary seal device 38 of FIG. 1 (see also FIG. 3), a pressure differential axially across the primary seal device 38 and to a lesser degree rotation of the rotating structure 26 may develop aerodynamic forces and apply a fluid pressure to the seal shoes 60 causing each seal shoe 60 to respectively move radially up and down relative to the outer seal land surface 36. The fluid velocity may increase as a gap between a respective seal shoe 60 and the outer seal land surface 36 increases, thus reducing pressure in the gap and drawing the seal shoe 60 radially inwardly toward the outer seal land surface 36. As the gap closes, the velocity may decrease and the pressure may increase within the gap, thus, forcing the seal shoe 60 radially outwardly from the outer seal land surface 36. The respective spring element 62 and its spring beams 108 may deflect and move with the seal shoe 60 to enable provision of a primary seal of the gap between the outer seal land surface 36 and seal shoe protrusions 82 within predetermined design tolerances.

[0132] While the primary seal device 38 described above is operable to generally seal the annular gap between the stationary structure 24 and the rotating structure 26, the fluid (e.g., gas such as air) may still flow axially through passages 110A-C (generally referred to as “110”) defined by radial air gaps between the elements 60, 108A, 108B and 48. The secondary seal assembly 44 and its one or more secondary seal devices 40 therefore are provided to seal off these passages 110 and, thereby, further and more completely seal the annular gap.

[0133] Each of the secondary seal devices 40 may be configured as a ring seal element such as, but not limited to, a split ring. Alternatively, one or more of the secondary seal devices 40 may be configured as a full hoop body ring, an annular brush seal or any other suitable ringtype seal.

[0134] The secondary seal devices 40 of FIG. 1 are arranged together in an axial stack. In this stack, each of the secondary seal devices 40 axially engages (e.g., contacts) another adjacent one of the secondary seal devices 40. The stack of the secondary seal devices 40 is arranged with the seal ring 42, which positions and mounts the secondary seal devices 40 with the stationary structure 24 adjacent the primary seal device 38. In this arrangement, the stack of the secondary seal devices 40 is operable to axially engage (e.g., contact) and form a seal between one or more or each of the first side surfaces 92 of the seal shoes 60 and an annular surface 112 of the seal ring 42. These surfaces 92 and 112 are axially aligned with one another, which enables the stack of the secondary seal devices 40 to slide radially against, butmaintain a seal engagement with, one or more or each of the side surfaces 92 as the seal shoes 60 move radially relative to the outer seal land surface 36 as described above.

[0135] The seal ring 42 may be a multi-component structure that includes a secondary seal device support ring 114 and a secondary seal device retention ring 116. The secondary seal device support ring 114 is configured with an annular full hoop body, which extends circumferentially around the axis 33. The secondary seal device support ring 114 includes the annular surface 112, and is disposed axially adjacent and may be axially engaged with (e.g., contact, abutted against, etc.) the seal base 48 at its seal base first side 46.

[0136] The secondary seal device retention ring 116 is configured with an annular full hoop body, which extends circumferentially around the axis 33. The secondary seal device retention ring 116 is disposed axially adjacent and is engaged with (e.g., axially contact, abutted against) the secondary seal device support ring 114, thereby capturing the stack of the secondary seal devices 40 within an annular channel 118 formed between the rings 114 and 116. The stack of the secondary seal devices 40, of course, may also or alternatively be attached to one of the rings 114, 116 by, for example, a press fit connection and / or otherwise.

[0137] Referring to FIG. 7, the non-contact seal 28 is configured with a small clearance gap 120 axially between the seal shoes 60 and the support ring 43 when the rotating structure 26 is at rest; see also FIGS. 1 and 2. However, under engine operating conditions, a pressure differential is applied axially across the non-contact seal 28. Under certain conditions, this pressure differential may deflect the primary seal device 38 and shift one or more of the seal shoes 60 axially towards the support ring 43. The clearance gap 120 is sized to account for such axial shifts of the seal shoe(s) 60. For example, when the seal shoes 60 axially shift, one or more of the seal shoes 60 may axially contact (e.g., rub radially along) the support ring first side 52 at (or about) the support ring inner end 58 to provide seal shoe damping. To reduce wear associated with this contact, the support ring 43 of FIG. 7 includes a (e.g., low friction) wear coating 122A bonded to and covering a metal substrate 124A of the support ring 43. Here, the support ring wear coating 122A extends along at least a portion of the support ring first side 52 along which the seal shoe(s) 60 may rub against during operation. Provision of this support ring wear coating 122A may reduce wear to the support ring 43 as well as to the seal shoe(s) 60. Moreover, the support ring wear coating 122A may be selected to provide a coefficient of friction which tunes the seal shoe damping for the specific noncontact seal application and / or environment. FIG. 15 generic ally / schematic ally shows abinder coating 122 as having matrix 600, a hardener 602, a metallic solid lubricant 604, and a non-metallic solid lubricant (e.g., CaF2) 606.

[0138] While the support ring wear coating 122A is described above as being applied to the support ring substrate 124A, the present disclosure is not limited thereto. For example, a wear coating 122B may also or alternatively be bonded to and cover a metal substrate 124B of each seal shoe 60 at its axial seal shoe second end 78. Here, the seal shoe wear coating 122B is configured to axially contact the support ring wear coating 122A or the support ring substrate 124A where, for example, the support ring wear coating 122A is omitted. In another example, referring to FIG. 8, a wear coating 122C may also or alternatively be bonded to and cover the seal shoe substrate 124B to form the first side surface 92 of the respective seal shoe 60. Here, the seal shoe wear coating 122C is configured to axially contact one of the secondary seal devices 40. In still another example, a wear coating 122D may also or alternatively be bonded to and cover a metal substrate 124D of at least one of the secondary seal devices 40. Here, the secondary seal device wear coating 122D is configured to axially contact the seal shoe wear coating 122C or the seal shoe substrate 124B where, for example, the seal shoe wear coating 122C is omitted. Of course, it is contemplated the wear coating may also or alternatively be applied to / included with one or more other components of the non-contact seal 28 of FIGS. 1 and 2, the rotating structure 26 and / or the rotating structure 26.

[0139] The wear coatings 122A-D (generally referred to as “122”) of FIGS. 7 and 8 may be applied to the respective substrates 124A, 124B, 124D (generally referred to as “124”) using various coating techniques. These coating techniques may include, but are not limited to, air plasma spraying, high velocity oxygen fuel (HVOF) spraying, high velocity air fuel (HVAF), or cold spraying.

[0140] In some embodiments, the wear coating 122 may (e.g., substantially or only) include a binder matrix and a solid lubricant material embedded and / or otherwise mixed within the binder matrix. Optionally, a hardener may be or otherwise include: glass; chromium-carbide (CI'SCT ; or chromium-oxide (C Oa). The binder matrix may be or otherwise include a nickel alloy such as an alloy including nickel (Ni), cobalt (Co), chromium (Cr), aluminum (Al), tantalum (Ta) and yttrium (Y); e.g., NiCoCrAlTaY. The solid lubricant material includes a metallic solid lubricant and calcium-fluoride (CaF2). The metallic solid lubricant may be or otherwise include any one, some or all of the following lubricant materials: copper (Cu);silver (Ag); and molybdenum (Mo). The solid lubricant may have little or preferably no barium- fluoride (BaF2).

[0141] In some embodiments, the wear coating 122 may (e.g., substantially or only) include a binder matrix, a hardener, and a solid lubricant material, where the hardener and the solid lubricant material are embedded and / or otherwise mixed within the binder matrix. The binder matrix may be or otherwise include a metal alloy such as: an alloy including nickel (Ni) and chromium (Cr) (e.g., NiCr); an alloy including cobalt (Co)) and chromium (Cr) (e.g., CoCr); an alloy including nickel (Ni) and cobalt (Co) (e.g., NiCo); or an alloying including nickel (Ni), molybdenum (Mo) and aluminum (Al) (e.g., NiMoAl).

[0142] The present disclosure, however, is not limited to the foregoing exemplary wear coating formulations. Moreover, while the foregoing wear coating 122 as described above as being applied to metal substrates in the rotational equipment assembly components of FIGS. 1 and 2, the present disclosure is not limited thereto. The wear coating(s) 122, for example, may also be applied to components of various other types of contact and / or non-contact seals as well as other rotational equipment components.

[0143] In some embodiments, as best seen in FIGS. 4 and 5, the primary seal device 38 and some or all of its elements (e.g., 48, 60 and 62) may be configured as a monolithic body. However, the present disclosure is not limited to such a primary seal device construction.

[0144] As described above, the rotational equipment assembly 20 of the present disclosure may be configured with various different types and configurations of rotational equipment. FIG. 9 illustrates one such type and configuration of the rotational equipment - a geared turbofan gas turbine engine 126. This turbine engine 126 includes various stationary structures (e.g., bearing supports, hubs, cases, etc.) as well as various rotors (e.g., rotor disks, shafts, shaft assemblies, etc.) as described below, where the stationary structure 24 and the rotating structure 26 can respectively be configured as anyone of the foregoing structures in the turbine engine 126 of FIG. 9, or other structures not mentioned herein.

[0145] The turbine engine 126 of FIG. 9 extends along the axis 33 between an upstream airflow inlet 128 and a downstream airflow exhaust 130. The turbine engine 126 includes a fan section 132, a compressor section 133, a combustor section 134 and a turbine section 135. The compressor section 133 of FIG. 9 includes a low pressure compressor (LPC) section 133A and a high pressure compressor (HPC) section 133B. The turbine section 135 of FIG. 9 includes a high pressure turbine (HPT) section 135A and a low pressure turbine (LPT) section 135B.

[0146] The engine sections 132-135B are arranged sequentially along the axis 33 within an engine housing 138. This engine housing 138 includes an inner case 140 (e.g., a core case) and an outer case 142 (e.g., a fan case). The inner case 140 may house one or more of the engine sections 133A-135B; e.g., an engine core 144. The outer case 142 may house at least the fan section 132.

[0147] Each of the engine sections 132, 133A, 133B, 135A and 135B includes a respective bladed rotor 146-150. Each of these bladed rotors 146-150 includes a plurality of rotor blades arranged circumferentially around and connected to one or more respective rotor disks. The rotor blades, for example, may be formed integral with or mechanically fastened, welded, brazed and / or otherwise attached to the respective rotor disk(s).

[0148] The fan rotor 146 is connected to a geartrain 152, for example, through a fan shaft 154. The geartrain 152 and the LPC rotor 147 are connected to and driven by the LPT rotor 150 through a low speed shaft 155. The HPC rotor 148 is connected to and driven by the HPT rotor 149 through a high speed shaft 156. The shafts 154-156 are rotatably supported by a plurality of bearings. Each of these bearings is connected to the engine housing 138 by at least one stationary structure such as, for example, an annular support strut.

[0149] During operation, air enters the turbine engine 126 through the airflow inlet 128. This air is directed through the fan section 132 and into a core flowpath 158 and a bypass flowpath 160. The core flowpath 158 extends sequentially through the engine sections 133A-135B.The air within the core flowpath 158 may be referred to as “core air”. The bypass flowpath 160 extends through a bypass duct, where the bypass flowpath 160 bypasses the engine core 144. The air within the bypass flowpath 160 may be referred to as “bypass air”.

[0150] The core air is compressed by the LPC rotor 147 and the HPC rotor 148 and directed into a combustion chamber 162 of a combustor in the combustor section 134. Fuel is injected into the combustion chamber 162 and mixed with the compressed core air to provide a fuelair mixture. This fuel air mixture is ignited and combustion products thereof flow through and sequentially drive rotation of the HPT rotor 149 and the LPT rotor 150. The rotation of the HPT rotor 149 and the LPT rotor 150 respectively drive rotation of the HPC rotor 148 and the LPC rotor 147 and, thus, compression of the air received from a core airflow inlet. The rotation of the LPT rotor 150 also drives rotation of the fan rotor 146. The rotation of the fan rotor 146 propels the bypass air through and out of the bypass flowpath 160. The propulsion of the bypass air may account for a majority of thrust generated by the turbine engine 126.

[0151] The rotational equipment assembly 20 may be included in various turbine engines other than the one described above as well as in other types of rotational equipment. The rotational equipment assembly 20, for example, may be included in a geared turbine engine where a geartrain connects one or more shafts to one or more rotors in a fan section, a compressor section and / or any other engine section. Alternatively, the rotational equipment assembly 20 may be included in a turbine engine configured without a geartrain; e.g., a direct drive turbine engine. The rotational equipment assembly 20 may be included in a geared or non-geared turbine engine configured with a single spool, with two spools (e.g., see FIG. 9), or with more than two spools. The turbine engine may be configured as a turbofan engine, a turbojet engine, a propfan engine, a pusher fan engine, an auxiliary power unit (APU) or any other type of turbine engine. The present disclosure therefore is not limited to any particular types or configurations of turbine engines or rotational equipment.

[0152] Various locations for the coating may involve contact seals. Several involve piston seal rings (PSR). These may include split or segmented rings in ID or OD grooves. Particular areas for coating are the low pressure side faces of the groove which contact associated faces of the seal. The coating may be directly atop the substrate alloy (e.g., Ni or Co-based alloy / superalloy) and the seal ring counterface may be ring substrate (e.g., Ni or Co-based alloy / superalloy) or a coating thereon. An example seal coating may include a CuAl base coating and a dry film lubricant (e.g., molybdenum disulfide or graphite) thereatop.

[0153] Examples include rotor seals 300 (FIG. 10) between the rotor shaft 302 (which may be a section of shaft 156) and rotor disk 304 bore 306. Rotor seals generally involve an ID groove 310 (in the shaft) so that centrifugal action expands the PSR 312 (e.g., a split ring (shown in cross-section through the shiplap joint)) into sealing contact of its OD surface 314 with the ID surface 308 of the mating disk bore. An axial pressure difference may bias the forward end face 316 of the PSR or aft end face 318 of the PSR into sealing contact with the associated wall 320, 322 of the groove. In an axial compressor, typically this will be an aft- to-fore pressure gradient biasing the forward end 316 of the PSR against the forward wall 320 of the groove.

[0154] Other examples include seals in mid turbine frames. As these seals are not subject to centrifugal loading, the groove may be an OD groove or an ID groove. FIG. 11 shows an OD 342 groove (in the outer member 340) with pressure-biased contact between the forward face 356 of the ring 350 and the forward (aft-facing) groove face 346 and ID contact of the ring IDface 352 with the inner member 360 OD surface 362. FIG. 11 also shows the ring OD surface 354, ring aft surface 358, groove aft surface 348, and groove face surface 347.

[0155] FIG. 12 shows an ID groove 380 (in the inner member 382) with pressure-biased contact between the forward face 356 of the ring and the forward face 386 of the groove and OD contact of the ring OD face 354 with the outer member 390 ID surface 392.

[0156] FIG. 13 shows an ID groove (in the inner member) with pressure-biased contact between the aft face of the ring the aft face of the groove and OD contact of the ring OD face with the outer member ID surface. FIG. 14 shows an OD groove with pressure-biased contact between the aft face of the ring and the aft groove face and ID contact of the ring ID face with the inner member OD surface.

[0157] Other locations include non-seal surfaces subject to occasional or intermittent contact movement.

[0158] In variations, there may be additional manufacture steps including pre-spray substrate grit blast and post spray grinding, heat treatments, and the like.

[0159] In variations, the material may be a layer in a multi-layer coating. For example, there may be a bondcoat (e.g., MCrAlY) intervening between the layer and the substrate.

[0160] While various embodiments of the present disclosure have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the disclosure. For example, the present disclosure as described herein includes several aspects and embodiments that include particular features. Although these features may be described individually, it is within the scope of the present disclosure that some or all of these features may be combined with any one of the aspects and remain within the scope of the disclosure. Accordingly, the present disclosure is not to be restricted except in light of the attached claims and their equivalents. When applied to a baseline seal or other apparatus, details of the baseline may influence details of any implementation.

Claims

CLAIMSWhat is claimed is:

1. An apparatus (20) for rotational equipment, comprising: a non-contact seal (28) including a primary seal device (38), a secondary seal assembly (44) and a support ring (43); the primary seal device including a plurality of seal shoes (60), a seal base (48) and a plurality of spring elements (62), the plurality of seal shoes arranged end-to-end around an axis in an array, the plurality of seal shoes comprising a first seal shoe, the seal base circumscribing the array of the plurality of seal shoes, the plurality of spring elements respectively connecting and extending an associated said seal shoe and the seal base; the secondary seal assembly configured to seal a gap between the seal base and the plurality of seal shoes, and the secondary seal assembly comprising a secondary seal device (40) contacting each of the plurality of seal shoes; and the support ring next to the plurality of seal shoes with the plurality of seal shoes located between the support ring and the secondary seal device, wherein: a first member of the non-contact seal comprises a substrate (124A; 124B; 124D) and a wear coating (122, 122A-122D) over the substrate; wherein the wear coating or a layer thereof includes a binder matrix (600) and a solid lubricant material (604, 606) within the binder matrix; the binder matrix comprises: one or more NiMoAl alloys; one or more MCrAlY alloys; one or more cobalt-based alloys; or combinations thereof; the solid lubricant material comprises CaF2 (606) at an overall level of at least 2.0 weight percent; the solid lubricant material comprises a metallic solid lubricant (604) at an overall level of at least 2.0 weight percent; and the wear coating or a layer thereof has no more than 1.0 weight percent BaF2, if any.

2. The apparatus of claim 1, wherein the binder matrix comprises said one or more cobalt-based alloys.

3. The apparatus of claim 1, wherein the binder matrix comprises an alloy including nickel cobalt.

4. The apparatus of claim 1, wherein the binder matrix comprises said one or more NiMoAl alloys.

5. The apparatus of claim 1, wherein the binder matrix comprises said one or more MCrAlY alloys comprising nickel, cobalt, chromium, aluminum, tantalum and yttrium.

6. The apparatus of claim 1, wherein the solid lubricant material comprises silver.

7. The apparatus of claim 1, wherein the wear coating or a layer thereof has no more than 0.50 weight percent BaF2, if any.

8. The apparatus of claim 1, wherein the solid lubricant material comprises silver as said metallic solid lubricant at an overall level of at least 2.0 weight percent.

9. The apparatus of claim 1, wherein the solid lubricant material comprises copper as said metallic solid lubricant at an overall level of at least 2.0 weight percent.

10. The apparatus of claim 1, wherein the solid lubricant material comprises molybdenum as said metallic solid lubricant at an overall level of at least 2.0 weight percent.

11. The apparatus of claim 1, wherein the coating comprises: not more than an overall level of at least 10, optionally 10 to 30, weight percent hardener (602), if any, within the binder matrix, said hardener selected from the group consisting of: glass particles; chromium carbide; chromium oxide; andcombinations thereof; and not more than 5.0% aggregate and 1.0% individually, additional phases.

12. The apparatus of claim 1, wherein the wear coating includes said chromium oxide at an overall level of at least 10, optionally 10 to 30, weight percent.

13. The apparatus of claim 1, wherein: the binder matrix comprises one of an alloy including nickel and chromium, an alloy including nickel and cobalt or an alloy including nickel, molybdenum and aluminum; and the solid lubricant material comprises at least one of silver, barium-fluoride or calcium-fluoride.

14. The apparatus of claim 13, wherein the wear coating further includes a hardener within the binder matrix, and the hardener comprises one of glass particles, chromium carbide or chromium oxide.

15. The apparatus of claim 11, wherein: the binder matrix comprises an alloy including nickel, cobalt, chromium, aluminum, tantalum and yttrium; and the solid lubricant material comprises at least one of copper, molybdenum, bariumfluoride or calcium-fluoride.

16. The apparatus of claim 1, wherein the first member comprises the support ring, and the wear coating is operable to contact the plurality of seal shoes.

17. The apparatus of claim 1, wherein the first member comprises the first seal shoe, and the wear coating is operable to contact one of the support ring or the secondary seal device.

18. The apparatus of claim 1, wherein the first member comprises the secondary seal device, and the wear coating is operable to contact the plurality of seal shoes.

19. An apparatus (20) for rotational equipment, comprising:a non-contact seal (28) including a primary seal device (38), a secondary seal assembly (44) and a support ring (43); the primary seal device including a plurality of seal shoes (60), a seal base (48) and a plurality of spring elements (62), the plurality of seal shoes arranged end-to-end around an axis in an array, the plurality of seal shoes comprising a first seal shoe, the seal base circumscribing the array of the plurality of seal shoes, the plurality of spring elements comprising a first spring element, and the first spring element connecting and extending between the first seal shoe and the seal base; the secondary seal assembly configured to seal a gap between the seal base and the plurality of seal shoes, and the secondary seal assembly comprising a secondary seal device (40) axially contacting each of the plurality of seal shoes; the support ring axially next to the plurality of seal shoes with the plurality of seal shoes located axially between the support ring and the secondary seal device; and at least one of the first seal shoe, the secondary seal device or the support ring comprising a binder matrix (600), a solid lubricant material (604, 606), and a hardener (602); the binder matrix comprising one or more NiMoAl alloys; one or more MCrAlY alloys; one or more cobalt-based alloys; or combinations thereof; the solid lubricant material within the binder matrix, the solid lubricant material comprising at least overall 2.0 weight percent metallic solid lubricant and at least overall 2.0 weight percent calcium- fluoride and no more than 1.0 overall weight percent barium-fluoride, if any; and the hardener within the binder matrix, the hardener comprising one of glass particles, chromium carbide or chromium oxide.

20. The apparatus of claim 19, wherein the binder matrix comprises said one or more NiMoAl alloys.

21. The apparatus of claim 19, wherein the metallic solid lubricant material comprises silver.

22. The apparatus of claim 19, wherein the metallic solid lubricant material comprises silver as said metallic solid lubricant at an overall level of at least 2.0 weight percent.

23. The apparatus of claim 19, wherein the overall weight percent barium- fluoride, if any is not more than 0.50 weight percent.

24. The apparatus of claim 19, wherein the hardener includes said chromium oxide at an overall level of at least 10, optionally 10 to 30, weight percent.

25. The apparatus of claim 19, wherein said at least one of the first seal shoe, the secondary seal device or the support ring comprising said binder matrix (600), solid lubricant material (604, 606), and hardener (602) as a coating on a metallic substrate.

26. An apparatus (20) for rotational equipment, comprising: a non-contact seal (28) including a primary seal device (38), a secondary seal assembly (44) and a support ring (43); the primary seal device including a plurality of seal shoes (60), a seal base (48) and a plurality of spring elements (62), the plurality of seal shoes arranged end-to-end around an axis in an array, the plurality of seal shoes comprising a first seal shoe, the seal base circumscribing the array of the plurality of seal shoes, the plurality of spring elements comprising a first spring element, and the first spring element connecting and extending between the first seal shoe and the seal base; the secondary seal assembly configured to seal a gap between the seal base and the plurality of seal shoes, and the secondary seal assembly comprising a secondary seal device (40) axially contacting each of the plurality of seal shoes; the support ring axially next to the plurality of seal shoes with the plurality of seal shoes located axially between the support ring and the secondary seal device; and at least one of the first seal shoe, the secondary seal device or the support ring comprising a binder matrix (600) and a solid lubricant material (604, 606); the binder matrix comprising an alloy including nickel, cobalt, chromium, aluminum, tantalum and yttrium; andthe solid lubricant material within the binder matrix, the solid lubricant material comprising copper, molybdenum, and calcium-fluoride each at at least 2.0 overall weight percent with no more than 1.0 overall weight percent barium fluoride.

27. A method for applying a coating (122A-122D), the method comprising: providing a wt% mixture of: at least 50.0 metallic binder precursor(s);2.0 to 20.0 metallic solid lubricant;2.0 to 10.0 CaF2; and no more than 1.0 BaF2, if any; and spraying the mixture on a metallic substrate.

28. The method of claim 27 wherein the metallic solid lubricant is selected from the group consisting of:Ag;Cu;Mo; and combinations thereof.

29. The method of claim 27 wherein the metallic solid lubricant comprises at overall wt. %:2.0 to 5.0 Ag.

30. The method of claim 27 wherein the metallic solid lubricant comprises at overall wt. %:2.0 to 5.0 Cu.

31. The method of claim 27 wherein the mixture further comprises a hardener comprising: one or more carbides; one or more ceramics; or a combination thereof.

32. The method of claim 27 wherein the mixture further comprises:CT2O3 powder.

33. The method of claim 27 wherein: the spraying is air plasma spray (APS), HVOF, HVAF, or cold spray.

34. The method of claim 27 wherein: the spraying is HVOF spraying.

35. The method of claim 27 wherein the metallic binder precursor(s) comprise: MCrAlY.

36. The method of claim 35 wherein: the MCrAlY is a NiCoCrAlY or CoNiCrAlY.

37. The method of claim 35 wherein: the mixture has a combined content said Mo and the Co of said MCrAlY of 12.5 weight percent to 45.0 weight percent.

38. The method of claim 35 wherein: the MCrAlY is a NiCoCrAlTaY.

39. The method of claim 38 wherein the NiCoCrAlTaY comprises by weight percent: Ni as a largest by weight constituent;20.0 to 26.0 Co;18.0 to 23.0 Cr;6.0 to 11.0 Al;2.0 to 6.0 Ta; and0.3 to 0.9 Y.

40. The method of claim 35 wherein one or more of: the MCrAlY is 50 to 90 weight percent of the powder mixture; the mixture further includes 0 to 30 weight percent chromium oxide hardener, if any; andthe combined: metallic solid lubricant;CaF2; andBaF2, if any, is 10 to 30 weigh percent.

41. The method of claim 35 wherein one or more of: the MCrAlY is 70 to 90 weight percent of the mixture; the mixture further includes 0 to 10 weight percent chromium oxide hardener, if any; and the combined: metallic solid lubricant;CaF2; andBaF2, if any, is 10 to 30 weigh percent.

42. The method of claim 35 wherein one or more of: the MCrAlY is 50 to 70 weight percent of the mixture; the mixture further includes 10 to 30 weight percent chromium oxide hardener; the combined: metallic solid lubricant;CaF2; andBaF2, if any, is 10 to 30 weigh percent; and the mixture includes no more than 5.0 weight percent other total.

43. The method of claim 27 wherein the metallic binder precursor(s) comprises: CoCr alloy.

44. The method of claim 43 wherein the CoCr alloy comprises:<2.0 C;<2.5 Mn;<2.5 Si;<0.1 P;<0.1 S;18.0-35.0Cr;<30.0 Ni;<8.0 Mo;<16.0 W;<4.0 Fe; and balance Co and no more than 7.0 each other element, if any, individually and 15.0 all other elements total.

45. The method of claim 43 wherein the CoCr alloy comprises:<2.0 C;<2.5 Mn;<2.5 Si;<0.1 P;<0.1 S;18.0-35.0Cr;<30.0 Ni;<8.0 Mo;<16.0 W;<4.0 Fe; and balance Co and no more than 1.0 each other element, if any, individually and 5.0 all other elements total.

46. The method of claim 27 wherein the metallic binder precursor(s) comprises: NiMoAl.

47. The method of claim 46 wherein the NiMoAl comprises by weigh percent:2.5 to 7.5 Mo;2.5 to 7.5 Al; andNi balance plus impurities,48. The method of claim 46 wherein one or more of: the NiMoAl is 60 to 80 weight percent of the mixture; the mixture further includes 10 to 30 weight percent chromium oxide hardener; and the combined: metallic solid lubricant;CaF2; andBaF2, if any, is 10 to 30 weigh percent.

49. An article comprising: a metallic substrate; and a wear coating (122, 122A-122D), wherein: the wear coating or a layer thereof includes a binder matrix (600) and a solid lubricant material (604, 606) within the binder matrix; the binder matrix comprises: one or more NiMoAl alloys; one or more MCrAlY alloys; one or more cobalt-based alloys; or combinations thereof; the solid lubricant material comprises CaF2 (606) at an overall level of at least 2.0 weight percent; the solid lubricant material comprises a metallic solid lubricant (604) at an overall level of at least 2.0 weight percent; and the wear coating or a layer thereof has no more than 1.0 weight percent BaF2 (606), if any.

50. The article of claim 49 wherein the wear coating or a layer thereof further comprises a hardener comprising: one or more carbides; one or more ceramics; or a combination thereof.

51. The article of claim 49 wherein the wear coating forms a counterface for a seal ring.

52. The article of claim 49 wherein the substrate forms a groove accommodating a seal ring and the wear coating is on a face of the groove facing the seal ring.

53. The article of claim 49 wherein the binder matrix comprises said one or more NiMoAl alloys.

54. The article of claim 49 wherein the metal solid lubricant comprises silver.

55. The article of claim 49 wherein the substrate forms a disk bore and the wear coating is on an inner diameter face of the disk bore.

56. The article of claim 49 wherein the substrate forms a component of a non-contact seal.

57. The article of claim 49 wherein the substrate forms a component of a non-contact seal.

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