Segmented barrier coating

Abstract

A coated article (20; 200; 400) has: a metallic body (22, 24) having connected surface troughs (30; 230); and a ceramic coating (26) atop the metallic body. The troughs have opposite walls (42) at least locally converging from proximally to distally. There may be gaps between the coating (26C; 26G) within the troughs and the coating (26A; 26B) aside the troughs or extending partially into the troughs. The coated article may be a gas turbine engine component.

Description

180093W001-U(24-248)SEGMENTED BARRIER COATINGCROSS-REFERENCE TO RELATED APPLICATION

[0001] Benefit is claimed of U.S. Patent Application No. 63 / 679,573, filed August 5, 2024, and entitled “Segmented Barrier Coating”, the disclosure of which is incorporated by reference herein in its entirety as if set forth at length.BACKGROUND

[0002] The disclosure relates to gas turbine engines. More particularly, the disclosure relates to segmented ceramic coatings for gas turbine engine components.

[0003] Gas turbine engines (used in propulsion and power applications and broadly inclusive of turbojets, turboprops, turbofans, turboshafts, industrial gas turbines, and the like) include ceramic coatings (thermal barrier coatings (TBC) and / or environmental barrier coatings (EBC)) on key gaspath-facing component surfaces. Example surfaces are airfoils (e.g., of blades and vanes), combustor panels, nozzles, and the like.

[0004] A number of proposals have been made for creating segmentation within the ceramic coating for purposes of stress / strain relief.SUMMARY

[0005] One aspect of the disclosure involves a coated article comprising: a metallic body having a plurality of connected surface troughs; and a ceramic coating atop the metallic body. The troughs have opposite walls at least locally converging from proximally to distally.

[0006] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the troughs are in a pattern, optionally a hexagonal pattern or a rectangular pattern. In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the pattern defines islands of 1.0 mm2to 40.0 mm2in area.

[0007] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the pattern covers at least 20 cm2in area with at least 50 cells.

[0008] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the troughs have: a maximum trough width WMAX; and a minimum trough width WMIN between the trough opening and the location of WMAX. (WMAX-WMIN) / 2 is at least 0.10 millimeter.

[0009] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the troughs have: a first trough width WMIN between the trough opening and the location of a greater trough width WMAX than said first trough width.180093W001-U(24-248)

[0010] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the troughs have a trough depth DT of 140 micrometers to 500 micrometers.

[0011] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the coating includes strips within the troughs.

[0012] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the troughs include respective central ridges.

[0013] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively: the coating is columnar with column height and an inter-columnar gap width; and the column height Hci away from the troughs is 100 micrometers to 500 micrometers.

[0014] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the metallic body comprises: a cast substrate; and a bondcoat between the cast substrate and the ceramic coating at least aside the troughs.

[0015] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the bondcoat comprises a diffusion bondcoat layer at least within the troughs.

[0016] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the bondcoat comprises an overlay bondcoat layer at least aside the troughs.

[0017] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively: the article is a blade or vane and the ceramic coating is on at least 50% of an outer surface of a pressure side of an airfoil of the blade or vane; or the article is a blade outer airseal (BOAS) and the ceramic coating is on at least 50% of a gaspath surface of the blade outer airseal; or the article is a combustor panel and the ceramic coating is on at least 50% of a gaspath surface of the combustor panel.

[0018] Other embodiments may include variations as discussed for aspects or embodiments above or below.

[0019] A further aspect of the disclosure involves a method for manufacturing the coated article, the method comprising: casting a metallic substrate; applying a bondcoat to the substrate; and applying the ceramic coating, the applying growing columnar islands of the coating aside the troughs and strips of coating within the troughs spaced from the islands by gaps.

[0020] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the casting comprises casting the metallic substrate with precursors of the troughs.180093W001-U(24-248)

[0021] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively: the casting comprises casting the metallic substrate without precursors of the troughs; and a subsequent machining forms the troughs or precursors thereof.

[0022] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the applying the ceramic coating forms fanning transitions from central portions of the islands to the gaps.

[0023] Other embodiments may include variations as discussed for aspects or embodiments above or below.

[0024] A further aspect of the disclosure involves a method for using the coated article, the method comprising: running the article in a gas turbine engine to expose the ceramic coating to CMAS; and wherein the CMAS does not bridge across the troughs above openings of the troughs.

[0025] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the CMAS does not bridge across the troughs above openings of the troughs.

[0026] Other embodiments may include variations as discussed for aspects or embodiments above or below.

[0027] A further aspect of the disclosure involves a coated article comprising: a metallic body having a plurality of connected surface troughs; and a ceramic coating atop the metallic body. The ceramic coating comprises: a first portion protruding from respective bases of the surface troughs; and a second portion aside the troughs and extending partially into the troughs. Gaps between the first portion and the second portion have span G2 of 10% to 100% of a thickness Hci of the second portion aside the troughs.

[0028] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the gaps’ span G2 is at 10% to 100% of a peak thickness Hc2 of the first portion.

[0029] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the first portion has a peak thickness Hc2 of 50% to 100% of a trough depth DT.

[0030] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively: the troughs are in a pattern; the troughs have sidewalls with rounded rim portions; the ceramic coating second portion is columnar and has a first subportion aside the troughs and a second subportion extending partially into the troughs; and the columns of the second subportion fan toward a centerplane of the associated trough along the associated rounded rim portion.

[0031] Other embodiments may include variations as discussed for aspects or embodiments above or below.180093W001-U(24-248)

[0032] A further aspect of the disclosure involves a coated article comprising: a metallic body having a plurality of connected surface troughs; and a ceramic coating atop the metallic body. The ceramic coating comprises: a first portion protruding from respective bases of the surface troughs; and a second portion aside the troughs and extending partially into the troughs. Gaps between the first portion and the second portion have span G2 of at least 500% of an inter- columnar gap size WG of the second portion aside the troughs.

[0033] In a further embodiment of any of the foregoing embodiments, additionally or alternatively, the troughs are in a pattern.

[0034] In a further embodiment of any of the foregoing embodiments, additionally or alternatively, the troughs have sidewalls with rounded rim portions.

[0035] In a further embodiment of any of the foregoing embodiments, additionally or alternatively, the ceramic coating second portion is columnar and has a first subportion aside the troughs and a second subportion extending partially into the troughs.

[0036] In a further embodiment of any of the foregoing embodiments, additionally or alternatively, the columns of the second subportion fan toward a centerplane of the associated trough along the associated rounded rim portion.

[0037] Other embodiments may include variations as discussed for aspects or embodiments above or below.

[0038] A further aspect of the disclosure involves a coated article comprising: a metallic body having a plurality of connected surface troughs; and a ceramic coating atop the metallic body. The troughs have: a median trough width WM of at least 150 micrometers; a trough depth DT of at least 140 micrometers.

[0039] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the trough depth DT is 140 micrometers to 500micrometers; and the median trough width WMAX is 50 percent to 300 percent of DT.

[0040] In a further embodiment of any of the foregoing embodiments, additionally and / or alternatively, the trough has non-undercut sidewalls.

[0041] In a further embodiment of any of the foregoing embodiments, additionally or alternatively, the troughs are in a pattern.

[0042] In a further embodiment of any of the foregoing embodiments, additionally or alternatively, the troughs have sidewalls with rounded rim portions.

[0043] In a further embodiment of any of the foregoing embodiments, additionally or alternatively, the ceramic coating is columnar and has a first portion aside the troughs and a second portion extending partially into the troughs.180093W001-U(24-248)

[0044] In a further embodiment of any of the foregoing embodiments, additionally or alternatively, the columns of the second subportion fan toward a centerplane of the associated trough along the associated rounded rim portion.

[0045] Other embodiments may include variations as discussed for aspects or embodiments above.

[0046] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG. 1 is a schematic cross-sectional view transverse to a trough through a barrier- coated substrate.

[0048] FIG. 2 is a first plan view of a trough pattern in the substrate.

[0049] FIG. 3 is a plan view of an alternative trough pattern in the substrate.

[0050] FIG. 4 is a schematic cross-sectional view transverse to a trough through a second barrier-coated substrate.

[0051] FIG. 5 is a schematic cross-sectional view transverse to a trough through a third barrier-coated substrate.

[0052] FIG. 6 is a schematic cross-sectional view transverse to a trough through a fourth barrier-coated substrate.

[0053] FIG. 7 is a schematic cross-sectional view transverse to a trough through a fourth barrier-coated substrate.

[0054] FIG. 8 is a view of the substrate of FIG. 1 after CMAS infiltration.

[0055] FIG. 9 is a schematic view of a blade.

[0056] FIG. 10 is a schematic view of a vane.

[0057] FIG. 11 is a schematic view of a combustor panel.

[0058] FIG. 12 is a schematic view of a blade outer airseal.

[0059] Eike reference numbers and designations in the various drawings indicate like elements.180093W001-U(24-248)DETAILED DESCRIPTION

[0060] FIG. 1 shows an article 20 having a substrate 22, a bondcoat 24, and ceramic barrier coating 26. In the example, the substrate is metallic (e.g., a cast nickel-based superalloy).

[0061] In the example, the bondcoat is a metallic bondcoat. A particular example is a diffusion aluminide having a thickness TB. Other examples (discussed below) include overlay coatings such as MCrAlY overlays (where M is Ni, Co, and / or Fe, e.g., a NiCoCrAlY). Others include combinations of diffusion and overlay or multiple overlay layers, and so forth.

[0062] The example barrier coating 26 is shown as a single columnar layer. An example columnar layer is applied by physical vapor deposition (PVD) such as electron beam physical vapor deposition (EB-PVD). Example barrier coating material is a yttria stabilized zirconia such as 7YSZ. Alternative application techniques include thermal spray (e.g., solution plasma spray or suspension plasma spray) and alternative materials include gadolinium-containing ceramics such as gadolinium zirconate (GdZ or GZO). In some implementations, there may be multiple coating layers including non-columnar layers such as air plasma sprayed layers. One example of a multi-layer coating involves a non-columnar base layer, a columnar intermediate / main layer, and a non-columnar topcoat. Additionally, there may be various infiltrants introduced after column formation.

[0063] The bondcoated substrate (substrate-bondcoat combination) includes a pattern of troughs 30 including portions within the substrate 22 itself. The example bondcoat thickness TB is less than the overall trough depth DT. The troughs may thus include a trough in the substrate (or intact substrate) and a trough in the bondcoated substrate (combination of substrate and bondcoat). This is distinguished from a shallow trough only in bondcoat. The nature of overlap between these troughs in cross-section may vary based upon where the bondcoat is and its thickness. As is discussed further below, trough depth DT and width may be on the order of the ceramic coating 26 thickness Hci.

[0064] FIGs. 2 and 3 alternatively show two example patterns of a rectangular (including the option of square) array pattern of troughs and a hexagonal or honeycomb pattern to define respective cells 540 and 542. The troughs are schematically represented by their centerplanes 520 other linear feature in planform. Example troughs are symmetric (subject to manufacturing variation) across their respective centerplanes 520. Example cell sizes of the pattern are measured based on the centerplanes / centerlines and are shown in FIG. 2 by their corresponding X and Y dimensions of Si and S2. For FIG. 3, a side of the hexagon is used as a size descriptor and is shown as S3.180093W001-U(24-248)

[0065] The patterning leaves islands (discussed further below) of otherwise typical coating (e.g., reflecting a baseline process on substrate lacking troughs) separated by gaps 60 (FIG. 1) at the troughs. The troughs have openings 66 to otherwise undisturbed surface. Opening width is shown as Wo. The troughs may broaden at intersections in the FIG. 2 or FIG. 3 pattern so as to provide the islands with rounded corners (both of the island coating and of the underlying substrate or bond coated substrate). Thus, the identified widths may represent median, mean, or modal values as may the depths. Example radius of curvature of the corners of the island footprint / planform is 5.0 micrometers to 50 micrometers.

[0066] The island size is selected to limit interface buckling stresses for barrier coating delamination. See, Hong-hui Yu and John W Hutchinson, “Delamination of thin film strips”, Thin Solid Films, January 1, 2003, Pages 54-63, Volume 423, Issue 1, Elsevier Science B.V., Amsterdam, Netherlands (Yu et al.). The trough width (and other properties below) may then be selected to not unduly compromise this while still providing beneficial protection at the troughs. Although regular arrays of pattern cells are shown, curved surfaces inherently impose a slight departure. But more significantly, irregular arrays may be tailored to specific anticipated conditions such as having smaller cells in areas subject to greater thermal stresses.

[0067] With the square grid example, island X and Y dimensions may be denoted by subtracting a trough width parameter from Si and S2. Particular trough width parameters are discussed below.

[0068] Assuming a square grid, then an island width / length should be on the order of lOx the thickness of the TBC coating to drop the interface energy release rate by 50% from a continuous surface. About 25% and 75% reduction correspond to 17x and 5x the thickness of the TBC. So for 250 micrometer thick TBC 1.25mm, 2.50mm, and 4.25mm respectively correspond with 75%, 50%, and 25% reduction in continuous film energy release rate. See, Yu et al.

[0069] Example coating island areas based on those values are 1.0 mm2to 20.0 mm2, more narrowly 4.0 mm2to 20.0 mm2or more broadly 1.0 mm2to 40.0 mm2. As noted above, these areas may be measured based upon the trough centerplanes / centerlines and thus may be slightly larger than islands of coating associated therewith or intact coated substrate surface aside the troughs.

[0070] The example troughs have a base section 40 and a pair of sidewalls 42 on opposite sides of the median or centerplane 520. In the FIG. 1 example along at least a portion of the troughs, the sidewalls converge inward toward the centerplane in a local outward direction 530 of the substrate. This creates a narrow part 34 of the trough (which may be a narrowest part of180093W001-U(24-248) the trough) spaced outwardly from a wider part of the trough (which may be a widest part 35 of the trough). FIG. 1 shows the net trough maximum width as WMAX and minimum width as WMIN SO that, with symmetry, an undercut span UC is half of their difference.

[0071] In general, example UC is at least 50 micrometers or at least 100 micrometers. More generally, UC may be selected to exceed expected CMAS deposited thickness and be on the scale of the barrier coating thickness or height Hci of principal coating 26A on the islands (e.g., 25% to 200% of Hci or 40% to 100% or 40% to 80%. Nevertheless, other embodiments (discussed below) may have lesser or no undercut.

[0072] Example trough depth may also be an example 25% to 200% of Hci. However, narrower limits may be expected to be higher than that for UC. For example, 50% to 200% or 75% to 200% or 75% to 150%. In terms of linear dimensions, example trough depth DT is at least 140 micrometers or 140 micrometers to 500 or 140 micrometers to 400 micrometers or 175 micrometers to 300 micrometers or 200 micrometers to 250 micrometers. It is possible that with some extremely thick bondcoat variations the bondcoat TB thickness may slightly exceed DT. Example TB is 20 micrometers to 250 micrometers, more narrowly 20 micrometers to 200 micrometers or 20 micrometers to 150 micrometers.

[0073] Example trough width characterized by said WMIN for the undercut trough is 150 micrometers to 1000 micrometers, more narrowly 250 micrometers to 1000 micrometers or 250 micrometers to 500 micrometers or 300 micrometers to 4500 micrometers. These values may also be used for the WM discussed below (e.g., relative to FIGs. 5 and 7).

[0074] As is discussed below, the trough converging / tapering may contribute to a shadowing effect during application of the ceramic and potentially application of the bondcoat (depending upon bondcoat technique). With pack or diffusion aluminide bondcoat, there may be little or no shadowing. With an overlay bondcoat (e.g., plasma sprayed, cathodic arc deposited or physical vapor deposited), there may be substantial shadowing such that portions of the sidewalls do not receive bondcoat. The lack of bondcoat on such areas may further synergize with shadowing during ceramic coating application to avoid ceramic deposition on those areas.

[0075] In one group of examples, the initial troughs in the substrate may be cast in place. For example, corresponding troughs may be formed during the molding of a sacrificial pattern (e.g., wax or elastomer). The pattern may be shelled for forming a casting shell and then pattern removed from the shell (e.g., destructively such as by melting). This leaves the shell with protrusions complementary to the troughs for casting the troughs (or precursors) in the casting. In the case of a wax pattern, the mold itself may be a highly flexible elastomer that can180093W001-U(24-248) disengage from the wax without damaging the troughs. In the case of an elastomeric pattern, the mold may be more robust (e.g., metal) and the elastomer may flex during disengagement therefrom.

[0076] In another group of examples, the initial troughs in the substrate may be machined (i.e., prior to bondcoat application).

[0077] In alternative examples, the troughs may be machined after bondcoat (overlay and / or diffusion) application. This would leave the troughs without bondcoat. Example such machining is a laser machining / milling such as water jet guided laser machining. Example waterjet guided laser apparatus is available from SYNOVA S.A., Duillier (Nyon), Switzerland.

[0078] Yet alternative machining variations may involve machining after a first bondcoat application but before a second. For example, the first may be an MCrAlY overlay and the second may be a pack or vapor diffusion aluminide. This would leave intact islands (unmachined substrate surface areas) with two bondcoat layers (or the effects of two stages) and the troughs (or depthwise majority thereof) with just the second (e.g., aluminide in the example).

[0079] The example patterning leaves islands of ceramic coating in the cells separated by narrow gaps 60 along the troughs. In the example troughs, the trough rims are rounded so as to be convex in the FIG. 1 section. Specifically, the example bondcoated substrate of FIG. 1 has troughs 30 with flaring openings 66 to adjacent untroughed surfaces 68 along the islands. These may be formed by rounded transitions 70 from the tapering portions of the sidewalls 42.

[0080] This rounding creates a fanning region 26B of the ceramic coating aside a principally vertical region 26A and where “vertical” is used to identify perpendicular to the main central surface of the cell aside the trough. Column height of the region 26A is shown as column height Hci. Example column height Hci is about 250 micrometers, more broadly 150 micrometers to 300 micrometers or 200 micrometers to 400 micrometers or 100 micrometers to 500 micrometers or 50 micrometers to 1000 micrometers. These may be measured as mean or median value. Generally, the particular article may influence desired thickness.

[0081] Example inter-column gap 62 width WG for the island ceramic WG is about 1.0 micrometers to 2.0 micrometers on average measured by taking a cross-section and examining under magnification. Particularly after CMAS, the fanning region 26B will have some effect on stresses / strains within the coating islands. Thus, the proxy trough width parameter used to deduct from grid size in measuring island size may include a portion of the fanning region 26B. An example width for such purpose is WMIN such that the rectangular islands are treated as having dimensions SI-WMIN and S2-WMIN, respectively for the stress calculation. Other trough180093W001-U(24-248) cross-sections lacking undercut may be associated with other reference widths (discussed further below).

[0082] Example grid size for a square grid has Si and S2 about ten times the column height Hci.

[0083] In the illustrated example, there is substantial shadowing of the trough to limit ceramic deposition. The shadowing effect may increase as the fanning coating grows and progressively further shadows the trough. The result may be to leave a strip of ceramic coating within the trough and which may be discontinuous / discontiguous with island coating or protruding from a thin sidewall coating joining the two. This trough coating is shown having a height. In the illustrated FIG. 1 embodiment, the example peak / maximum column height Hc2 for the trough strip 26C is less than the overall trough depth DT SO that the trough strip does not protrude from the trough. Additionally, the gap 80 between the strip and the fanning ceramic has a dimension G2 which may be substantially larger than the characteristic inter-column gap 62 width WG for both the island ceramic and the strip ceramic. Example G2 is at least 5.0 micrometers or at least 7.0 micrometers, more particularly 5.0 micrometers to 100 micrometers or 7.0 micrometers to 75 micrometers with alternative respective lower limits of 10 micrometers andl5 micrometers and upper limits of 30 micrometers, 40 micrometers and 50 micrometers. FIG. 1 also shows a gap dimension G3 between the two adjacent fanning sections. Example G3 is between WMIN - 0.25*(2*Hci) and WMIN - (2*Hci) inclusive, more narrowly between WMIN - 0.30*(2*Hci) and WMIN - 0.75*(2*Hci) inclusive or between WMIN - 0.35*(2*Hci) and WMIN - 0.60*(2*Hci) inclusive.

[0084] As noted above, example articles include blades, vanes, combustor panels, blade outer air seals (BOAS), nozzles, and the like. The ceramic coating may be on substantially the entire gaspath surface of such article (e.g., the airfoil lateral perimeter of a blade or vane along with the gaspath-facing an ID platform or OD shroud / platform). For an example combustor panel, this may be the surface facing the interior of the combustor.

[0085] In general, the ceramic coating may be on at least one half of such gaspath surface. Additionally, the trough pattern need not be under substantially the entire coated surface but may be under a more limited portion of the ceramic coating to address areas of particular combinations of CMAS exposure and thermal stress. For example, the patterning may be under an example at least 50% of a relevant ceramic area (e.g., at least 50% of ceramic on an airfoil or a side thereof or on the OD or ID platform surfaces of a blade or vane). Regarding patterning a single airfoil side, examples may have the pattern on the airfoil pressure side where CMAS180093W001-U(24-248) is prone to build up but not on the airfoil suction side where CMAS does not accumulate but where aerodynamic smoothness / flatness is of greater importance.

[0086] In use, the barrier coating 26C in the groove will generally protect the groove but the discontinuity with the island barrier coating 26A will maintain the delamination resistance. The flaring coating 26B, due to greater progressive inter-column spacing, will not substantially increase delamination stresses of the coating 26A. However, it will still provide protection at the trough opening. Additionally, the flaring of the coating 26C over the trough will further thermally shadow the trough and improve temperature resistance. The trough dimensions may be selected to provide a desired gap 80 size G2 to limit / prevent mechanical interaction.

[0087] The trough taper / undercut will shadow the tapering portions of the sidewalls 42 and outboard portions of the base 40 and prevent barrier coating deposition thereon. This helps maintain the mechanical separation of the coating islands from each other and from the trough strip 26C.

[0088] FIG. 8 shows the FIG. 1 coated substrate after in-service exposure to CMAS. The CMAS 180 has formed an accumulation 180X atop the island ceramic 26A with a thickness shown as HCM. The CMAS penetrates (infiltrations 180A) depthwise into the ceramic 26A inter-column gaps by a depth of DCM. The CMAS has similarly penetrated (infiltrations and 180C) the strip ceramic 26C. The CMAS has penetrated (infiltrations 180B) the broader tapering gaps of the fanning ceramic 26B. The gap between the CMAS-coated fanning ceramic 26B and strip ceramic 26C is still preserved but at a diminished value G'2. In practice, particulate CMAS may accumulate and even fully bridge between the coating sections 26B and 26C. However, upon melting, the CMAS may start to consolidate and infiltrate into the intercolumnar gaps, reducing the amount available to bridge (along with surface tension potentially reducing bridging to re-open gaps).

[0089] Upon melting of CMAS. Capillary action may draw CMAS deep into the intercolumnar gaps so that DCM. may increase while HCM at least temporarily decreases. DCM may quickly reach a few micrometers and, at least after multiple use cycles, may approach full Hci. HCM may be 5 or more micrometers or 25 or more micrometers, e.g., 5 micrometers to 40 micrometers.

[0090] FIG. 4 shows an example coated substrate 200 wherein two separate machining passes machine the respective sidewalls using a tool (a bit for mechanical machining or an electrode for electro-discharge machining (EDM)) or laser ablation / engraving are made after applying bondcoat. This results in the troughs 230 lacking bondcoat. Other alternatives include waterjet machining. The particular two-pass machining may, depending on bit or180093W001-U(24-248) electrode shape or laser parameters, leave two lateral sections 230A, 230B partially separated by a central ridge 231 of substrate material. The ridge may bear a fanning strip 26D of columnar ceramic that may protrude from the trough opening and proud of the surface 68. FIG. 4 also shows gaps 280 of span G2 between the strip 26D and adjacent island ceramic 26A. Relative to FIG. 1, the undercut is shifted fairly outboard toward the surface 68 and reduced in span UC but still provides a shadowing effect during ceramic deposition. Example laser engraving apparatus is available from SYNOVA S.A., Duillier (Nyon), Switzerland. Alternative processes may avoid forming the ridge or may involve at least partially removing it (e.g., a third machining pass).

[0091] The example machining does not leave a rounded transition such as 70 of FIG. 1. However, alternative machinings may. The opening width is WMIN. A further alternative (not shown) is the possibility of having a half undercut trough such as might be formed by making only one of the angled machining passes of FIG. 4. The relevant trough transverse dimension may be a median width.

[0092] FIG. 5 shows an example coated substrate 300 without sidewall undercut but a large trough opening width Wo. The example opening width is the maximum width. The example machining does leave a rounded transition such as 70 of FIG. 1. In addition to those external rounds, there may be internal rounds forming transitions between the sidewalls and base. The rounded opening transitions form fanning sections 26F of the ceramic coating with coating sections 26H that extend down the sidewall, ultimately merging with a trough base strip 26G. This leaves gaps 330A, 330B between the sidewall coating 26H and the strip coating 26G. These gaps may be partially preserved upon CMAS exposure and thus provide (along with the gap 60) transverse / lateral mechanical compliance maintaining the mechanical decoupling of the island coating on the two sides of the trough. An example median width WM may, in the case of perfect quarter round transition and parallel sidewall sections therebetween, may fall along a central depthwise region of the trough. In the idealized case, that median width will be a modal width and may also even be a mean width. Such WM may form the proxy width discussed above.

[0093] FIG. 6 shows an example article 400 as a coated substrate with undercut but with isolated bondcoat along the base of the trough. This, for example, may be formed by pre-forming a trough in the substrate and then applying bondcoat via physical vapor deposition or thermal spray (instead of aluminization). Thus, the example bondcoat fully covers the untroughed substrate but covers only a central strip along the base of each trough180093W001-U(24-248) due to shadowing such as discussed above for the ceramic. The ceramic is similarly shadowed to that discussed for FIG. 1.

[0094] Further variations may, like FIG. 5, lack undercut but have otherwise- shaped troughs. Examples include more semi-circular shaped troughs (either with or without rounded transitions such as 70) such as in the article 600 of FIG. 7. With such a semi-circular trough, there may still be enough lateral compliance due to the central gap in the portion of the coating outboard of the trough opening. Such may lack the WMIN of FIG. 1 or the relevant modal width value of FIG. 5. A relevant width, however, may still be a median width.

[0095] Yet further variations (not shown), there may not be a strip / island of ceramic coating along the trough base. One example involves forming the troughs after ceramic coating application (e.g., via laser machining such as described above for pre-coating trough formation). A potential benefit is manufacturing sequence benefit for complex shape parts by doing trough machining last. Or it may involve removing the strip such as by water guided laser machining. Fully or partially removing ceramic coating from the trough may have the benefit of limiting bridging by CMAS such as by increasing G2. Similarly, G2 may be increased by partially removing the fanning coating (e.g., 26B). FIG. 1 also shows a gap G3 between the two adjacent fanning sections. This may be the relevant dimension in situations of removal of the strip coating 26C.

[0096] FIG. 9 shows a blade 900 having an airfoil 902 extending outward from a platform 904. The blade includes an attachment root 906 inboard of the platform. The platform 904 has an outboard gaspath surface 908. The airfoil has a surface comprising a leading edge 910, a trailing edge 911, a pressure side 912, and a suction side 913. The airfoil extends from an inboard end at the platform to an outboard end and an outboard end at a tip 914. The relevant gaspath surface of the blade for ceramic coating is thus the pressure and suction sides and the platform gaspath surface. Alternate blades may have features such as shrouded tips (not shown) and internal cooling passageway networks (not shown).

[0097] FIG. 10 shows a vane 930 which may have a similar airfoil to the blade 900. The airfoil extends from an inboard end at an inner diameter shroud or platform or band segment 932 to an outboard end at an outer diameter / outboard shroud or band segment 933. The segments 922, 933 have respective outer diameter and inner diameter gaspath surfaces 934 and 935.

[0098] FIG. 11 shows a component as a combustor panel (e.g., a floatwall panel) 950. The panel 950 may be formed having a body 951 shaped as a generally frustoconical segment180093W001-U(24-248) having respective inboard and outboard surfaces 952 and 953. The example inboard surface is thus a gaspath-facing surface formed as a frustoconical segment.

[0099] The example panel is configured for use in an annular combustor circumscribing the engine centerline. In the example panel, the inboard surface 952 forms an interior surface (i.e., facing the combustor interior) so that the panel is an outboard panel. For an inboard panel, the inboard surface would be the exterior surface. Accordingly, mounting features such as studs 955 extend from the outboard surface for securing the panel relative to the engine. The ceramic coating may be at least on the interior surface.

[0100] An example annular combustor is formed by a number of concentric inner rings and outer rings of such panels. A plurality of such rings are arrayed end-to-end at both inner diameter (ID) and outer diameter (OD) boundaries. These rings may extend downstream from a bulkhead (also a ring of panels) mounting fuel injector nozzles, air swirlers, and the like. The panel rings may extend downstream to a guide vane ring at the inlet to the turbine section.

[0101] The example panel body 951 further includes an upstream / leading edge 956, a downstream / trailing edge 957 and lateral (circumferential end) edges 958 and 959. A flow direction along each such panel may be generally from the upstream / leading edge to the downstream / trailing edge. Along one or more of the edges or elsewhere, the panel may include rails or standoffs 960 extending from the exterior surface 953 for engaging a combustor shell (not shown). The example panel includes a circumferential array of large apertures 961 for the introduction of process air (these are typically cast in the substrate). Smaller apertures (not shown) may be provided for film cooling (these are typically machined post-casting). Moreover, select panels may accommodate other openings (these are typically cast in the substrate) for spark plug or igniter or sensor placement.

[0102] FIG. 12 shows a blade outer air seal (BOAS) segment 970. The BOAS has a main body portion 971 having a leading / upstream / forward end 972 and a trailing / downstream / aft end 973. The body has first and second circumferential ends or matefaces 974 and 975. The body has an ID face 976 (which may be the most relevant surface portion for the ceramic coating) and an OD face 977. To mount the BOAS to environmental structure (e.g., a main portion of the case), the exemplary BOAS has a plurality of mounting hooks. The exemplary BOAS has a forward mounting hook 978 and an aft hook 979.

[0103] The assembled ID faces of the circumferential array of BOAS segments thus locally bound an outboard extreme of the core flowpath through the engine. The BOAS may have features (not shown) for interlocking the array. Exemplary features include finger and180093W001-U(24-248) shiplap joints. The example BOAS also has an apertured plate 980 mounted to the body OD face to enclose a cooling plenum of the body having outlets along the matefaces and optionally elsewhere.

[0104] The use of “first”, “second”, and the like in the following claims is for differentiation within the claim only and does not necessarily indicate relative or absolute importance or temporal order. Similarly, the identification in a claim of one element as “first” (or the like) does not preclude such “first” element from identifying an element that is referred to as “second” (or the like) in another claim or in the description.

[0105] One or more embodiments have been described. Nevertheless, it will be understood that various modifications may be made. For example, when applied to an existing baseline configuration, details of such baseline may influence details of particular implementations. Accordingly, other embodiments are within the scope of the following claims.

Claims

180093W001-U(24-248)CLAIMSWhat is claimed is:

1. A coated article (20; 200; 400) comprising: a metallic body (22, 24) having a plurality of connected surface troughs (30; 230); and a ceramic coating (26) atop the metallic body, wherein: the troughs have opposite walls (42) at least locally converging from proximally to distally.

2. The coated article of claim 1 wherein: the troughs are in a pattern.

3. The coated article of claim 2 wherein: the pattern is a hexagonal pattern.

4. The coated article of claim 2 wherein: the pattern is a rectangular pattern.

5. The coated article of claim 2 wherein: the pattern defines islands of 1.0 mm2to 40.0 mm2in area.

6. The coated article of claim 2 wherein: the pattern covers at least 20 cm2in area with at least 50 cells.

7. The coated article of claim 1 wherein the troughs have: a maximum trough width WMAX; and a minimum trough width WMIN between the trough opening and the location of WMAX, wherein:(WMAX-WMIN) / 2 is at least 0.10 millimeter.

8. The coated article of claim 1 wherein the troughs have: a first trough width WMIN between the trough opening and the location of a greater trough width WMAX than said first trough width.180093W001-U(24-248)9. The coated article of claim 1 wherein the troughs have: a trough depth DT of 140 micrometers to 500 micrometers.

10. The coated article of claim 1 wherein: the coating includes strips (26C; 26D)within the troughs.

11. The coated article of claim 10 wherein: the troughs include respective central ridges (231).

12. The coated article of claim 1 wherein: the coating is columnar with column height and an inter-columnar gap width; and the column height Hci away from the troughs is 100 micrometers to 500 micrometers.

13. The coated article of claim 1 wherein the metallic body (22, 24) comprises: a cast substrate (22); and a bondcoat (24) between the cast substrate and the ceramic coating at least aside the troughs.

14. The coated article of claim 13 wherein: the bondcoat comprises a diffusion bondcoat layer at least within the troughs.

15. The coated article of claim 14 wherein: the bondcoat comprises an overlay bondcoat layer at least aside the troughs.

16. The coated article of claim 1 wherein: the article is a blade (900) or vane (930) and the ceramic coating is on at least 50% of an outer surface of a pressure side (912) of an airfoil (902) of the blade or vane.

17. The coated article of claim 1 wherein: the article is a blade outer airseal (BOAS) (970) and the ceramic coating is on at least 50% of a gaspath surface (976) of the blade outer airseal.

18. The coated article of claim 1 wherein:180093W001-U(24-248) the article is a combustor panel (950) and the ceramic coating is on at least 50% of a gaspath surface (952) of the combustor panel.

19. A method for manufacturing the coated article of claim 1, the method comprising: casting a metallic substrate (22); applying a bondcoat (24) to the substrate; and applying the ceramic coating (26), the applying growing columnar islands (126A) of the coating aside the troughs and strips of coating (26C; 26D; 26G) within the troughs spaced from the islands by gaps (80; 280).

20. The method of claim 19 wherein: the casting comprises casting the metallic substrate with precursors of the troughs.

21. The method of claim 19 wherein: the casting comprises casting the metallic substrate without precursors of the troughs; and a subsequent machining forms the troughs or precursors thereof.

22. The method of claim 19 wherein: the applying the ceramic coating forms fanning transitions (26B; 26F) from central portions of the islands to the gaps.

23. A method for using the coated article of claim 1, the method comprising: running the article in a gas turbine engine to expose the ceramic coating to CMAS (180).

24. The method of claim 23 wherein: the CMAS does not bridge across the troughs above openings (66) of the troughs.

25. A coated article (20; 200; 300; 400) comprising: a metallic body (22, 24) having a plurality of connected surface troughs (30; 230; 330); and a ceramic coating (26) atop the metallic body, wherein: the ceramic coating comprises: a first portion protruding from respective bases of the surface troughs; and180093W001-U(24-248) a second portion aside the troughs and extending partially into the troughs; and gaps between the first portion and the second portion have span G2 of 10% to 100% of a thickness Hci of the second portion aside the troughs.

26. The article of claim 25 wherein: the gaps’ span G2 is at 10% to 100% of a peak thickness Hc2 of the first portion.

27. The article of claim 25 wherein: the first portion has a peak thickness Hc2 of 50% to 100% of a trough depth DT.

28. The article of claim 25 wherein: the troughs are in a pattern.

29. The article (20; 300; 400) of claim 25 wherein: the troughs have sidewalls with rounded rim portions.

30. The article of claim 25 wherein: the ceramic coating second portion is columnar and has a first subportion aside the troughs and a second subportion extending partially into the troughs.

31. The article of claim 30 wherein: the columns of the second subportion fan toward a centerplane (520) of the associated trough along the associated rounded rim portion.

32. A coated article (20; 200; 300; 400) comprising: a metallic body (22, 24) having a plurality of connected surface troughs (30; 230; 330); and a ceramic coating (26) atop the metallic body, wherein: the ceramic coating comprises: a first portion protruding from respective bases of the surface troughs; and a second portion aside the troughs and extending partially into the troughs; and gaps between the first portion and the second portion have span G2 of at least 500% of an inter-columnar gap size WG of the second portion aside the troughs.180093W001-U(24-248)33. The article of claim 32 wherein: the troughs are in a pattern.

34. The article of claim 32 wherein: the troughs have sidewalls with rounded rim portions.

35. The article of claim 34 wherein: the ceramic coating second portion is columnar and has a first subportion aside the troughs and a second subportion extending partially into the troughs.

36. The article of claim 35 wherein: the columns of the second subportion fan toward a centerplane (520) of the associated trough along the associated rounded rim portion.

37. A coated article (20; 200; 300; 400; 600) comprising: a metallic body (22, 24) having a plurality of connected surface troughs (30; 230); and a ceramic coating (26) atop the metallic body, wherein: the troughs have: a median trough width WM of at least 150 micrometers; and a trough depth DT of at least 140 micrometers.

38. The article of claim 37 wherein: the trough depth DT is 140 micrometers to 500 micrometers; and the median trough width WMAX is 50 percent to 300 percent of DT.

39. The article (300; 600) of claim 37 wherein: the trough has non-undercut sidewalls.

40. The article of claim 37 wherein: the troughs are in a pattern.

41. The article (20; 300; 400; 600) of claim 37 wherein:180093W001-U(24-248) the troughs have sidewalls with rounded rim portions.

42. The article of claim 37 wherein: the ceramic coating is columnar and has a first portion aside the troughs and a second portion extending partially into the troughs.

43. The article of claim 37 wherein: the columns of the second subportion fan toward a centerplane (520) of the associated trough along the associated rounded rim portion.

Images