Patent ID: 12195403

DETAILED DESCRIPTION

Slurry infiltration of a preform positioned in a mold body under vacuum has been used to draw a slurry into the preform pores to form CMC components. A mold body having surfaces directly adjacent to or touching a surface of the preform may inhibit slurry infiltration at those surfaces. Enlarging the mold body may promote even slurry infiltration at all surfaces of the perform, but may result in excess cured slurry on the surface of the component. The excess cured slurry may be removed in additional post-processing steps, which may be extensive to achieve a desired surface finish, may damage the component, or both.

To improve slurry infiltration, provide an improved surface finish (e.g., profile tolerance), and/or reduce post-processing steps, the present disclosure is directed to slurry infiltration systems and techniques utilizing one or more inflatable bladders. In an example bladder cast slurry process, after a liquid slurry is introduced into a mold body, a vacuum may be applied to the mold body to promote infiltration of the slurry into a preform. Once the slurry fully encompasses preform, the bladders may be inflated with a fluid. The bladders may expand until mold surfaces of the bladders contact respective surfaces of the preform. The mold surfaces of the bladders may conform to contact points on the preform that define the outermost surface of the component. Additionally, or alternatively, the bladders may further promote infiltration of the slurry into the preform. With the bladders inflated, the slurry may be dried and/or cured. After drying and/or curing, the bladders may be deflated, and the component may be removed. The component may include substantially smooth bladder-casted surfaces having an improved surface finish (e.g., a bladder cast finish) with reduced post-processing steps, compared to other slurry infiltration systems and techniques.

FIG.1. is a conceptual and schematic diagram illustrating an example system100for slurry infiltration of an article101with inflatable bladders. System100includes mold body102, inflatable bladders104A,104B,104C, and104D (collectively, bladders104), computing device106, slurry reservoir108, vacuum pump110, and fluid reservoir112.

Article101may include a component of a high temperature mechanical system, such as a component of a gas turbine engine. For example, article101may include a seal segment, a blade track, an airfoil, a blade, a vane, a combustion chamber liner, or other gas turbine engine component. Article101includes a substrate material (e.g., a CMC substrate) having inner spaces (e.g., pores) that may be at least partially filled with solid particles of a slurry via slurry infiltration. For example, the slurry may include solid particles in a carrier material (e.g., one or more solvents), and optional additives configured to aid in the infiltration of the slurry.

Mold body102defines a cavity114that is configured to receive article101. For example, at least one surface of mold body102may be removable or openable to insert article101into cavity114. During a slurry infiltration process, article101is positioned in cavity114of mold body102. In some examples, mold body102may include one or more support structures protruding into cavity114that are configured to retain article101in selected position and/or orientation within cavity114. In this way, mold body102may surround and optionally support article101for slurry infiltration. Mold body102(including the optional support structures) may be formed of any suitable material including, for example, graphite, silica, alumina, or one or more materials that are non-reactive with the slurry or article101during the slurry infiltration process. In some examples, the material from which mold body102is formed may be selected to allow release of the dried and/or cured slurry after completion of the slurry infiltration process.

After closing mold body102, a slurry may be introduced into cavity114. For example, slurry reservoir108may include one or more pumps, one or more mixers, one or more control devices (e.g., valves, regulators, or the like), and/or one or more hoppers or containers configured to store and dispense one or more components of a selected slurry (e.g., the carrier material, the solid particles, and/or the additives). Computing device106may control slurry reservoir108to pump or otherwise introduce the slurry into cavity114via a slurry feedline109. Although illustrated as including one slurry feedline109, in some examples, slurry reservoir108may be fluidly coupled to cavity114by two or more slurry feedlines. Fluidly coupling slurry reservoir108to cavity114with two or more slurry feedlines may provide more uniform coverage of article101during slurry introduction.

In some examples, prior to or during introduction of the slurry, a vacuum may be drawn in cavity114to purge gas from inner spaces (e.g., pores) of article101. For example, computing device106may control vacuum pump110fluidly coupled to cavity114via vacuum line111to purge gas from cavity114. In some examples, mold body102may include one or more pressure sensors operatively coupled to computing device106to enable computing device106to draw vacuum to a selected pressure. Although illustrated as including one vacuum line111, in some examples, vacuum pump110may be fluidly coupled to cavity114by two or more vacuum lines. Drawing a vacuum (e.g., relative to atmospheric pressure) may improve infiltration of the slurry into the inner spaces of article101by reducing pressure gradients that may form within inner spaces of article101as the slurry infiltrates the inner spaces.

The slurry infiltration may be conducted at any temperature, including room temperature (e.g., between about 20° C. and about 35° C.), suitable for the selected materials of system100, article101, and the slurry. In this regard, system100may include one or more temperature sensors and/or one or more temperature regulators (not illustrate), such as, for example, one or more electronic or liquid heat exchangers.

After introduction of the slurry, bladders104may be inflated using fluid reservoir112. For example, bladders104may be fluidly coupled to fluid reservoir112via fluid feedlines113. Fluid reservoir112may include one or more pumps, one or more control devices (e.g., valves, regulators, pressure sensors, flow sensors, or the like), and/or one or more containers configured to pump a fluid into bladders104at a selected rate, to a selected pressure, or both. The fluid may include an incompressible fluid, such as water, an alcohol or a liquid (e.g., at the temperature of the slurry infiltration process) that is non-reactive with the substrate material of article101, or a compressible fluid, such as air, nitrogen, hydrogen, or a gas (e.g., at the temperature of the slurry infiltration process) that is non-reactive with the substrate material of article101. In some examples, computing device106may control fluid reservoir112to inflate bladders104at a selected rate, to a selected pressure, or both. Inflation of bladder104may increase the pressure within cavity114. Additionally, or alternatively, inflation of the bladders104may cause at least a portion of bladders104to contact a respective surface of article101. The increase in pressure and contact of bladders104with a surface of article101may improve infiltration by urging the slurry into the inner spaces of article101.

In some examples, bladders104may be inflated simultaneously, e.g., at a substantially similar rate and/or to a substantially similar pressure. As used herein, a substantially similar rate and/or a substantially similar pressure means the same rate and/or pressure within the tolerances of the pump and/or control devices of fluid reservoir112. Simultaneously inflating bladders104may promote more even infiltration of

In some examples, one or more bladders104may be selectively inflated, e.g., in a particular sequence of rates and/or pressures. Selectively inflating bladders104may prevent or reduce movement of article101during inflation of bladders104, reduce damage or deformity of article101during inflation of bladders104, improve infiltration of the slurry into article101, or both.

Bladders104may include any suitable material configured to inflate in response to the introduction of the fluid. For example, bladders104may include polymeric material, an elastomer, natural rubbers, styrene-butadiene block copolymers, polyisoprene, polybutadiene, ethylene propylene rubber, ethylene propylene diene rubber, silicone elastomers, fluoroelastomers, polyurethane elastomers, nitrile rubber, polytetrafluoroethylene, nylon, neoprene, or Kalrez available from DuPont de Nemours, Inc., Wilmington, Delaware.

The inflatability of bladders104enable simpler mechanical movement compared to rigid mold bodies. For example, bladders104are inflated by fluid reservoir that may be external to mold body102and do not require any moving mechanical parts such as levers or gears within mold body102.

Additionally, or alternatively, a flexibility of bladders104allows for greater variation in an exterior surface of article101compared to rigid mold bodies. For example, a flexibility of bladders104may better contour to an imperfect surface geometry of article101compared to a rigid mold body that cannot flex to contour to an imperfect surface geometry of article101. In this way, bladders104may provide a more consistent surface profile relative to the surface geometry of article101, reduce areas of excess slurry between the bladder104and the surface of article101compared to a rigid mold body, or both.

Bladders104include a shape configured to, when in an inflated configuration, define a selected mold shape. For example, as illustrated inFIG.1, article101includes a turbine engine seal segment having a base117and tips119A and119B (collectively, tips119). Bladder104A includes a rectangular prism shape configured to contact an interior surface of base117and an interior surface of each of tips119. Bladders104B and104C include triangular prism shapes configured to contact an interior surface base117and an interior surface of tip119A and tip119B, respectively. Bladder104D includes a rectangular prism shape configured to contact an exterior surface of base117. In this way, bladders104include a shape that defines a selected mold shape of article101.

Although illustrated as having at least some edges of article101exposed (e.g., not in contact with a bladder104), in other examples, bladders104may be shaped to contact all surfaces of article101. Alternatively, bladders104may be arranged and/or shaped to contact only selected surfaces of article101. For example, bladders104may be shaped to contact surfaces of article101selected to have a predetermined surface finish tolerance, e.g., a bladder cast finish.

In some examples, bladders104may include one or more features configured to control a direction of inflation of bladders104. For example, as illustrated inFIG.1, bladders104include an optional bellows (e.g., bellows105C of bladder104C). Bellows105C defines a bulge or bulbous structure near the base of bladder104C that extends in a direction substantially parallel (e.g., parallel or nearly parallel within common slurry mold body design tolerances) to an adjacent wall of mold body102. During inflation of bladder104C, bellow105C may urge bladder104C to inflate in a direction substantially perpendicular to bellows105C (illustrated as arrow107C). Each of bladders104A,104B, and104D also are illustrated as including respective bellows configured to urge the respective bladders104in a respective direction during inflation.

Although illustrated as a bellows, in other examples, bladders104may include additional or alternative features configured to control a direction of inflation of bladders104. For example, bladders104may include bands of relatively less elastic material, e.g., relative to other material of bladder104, that control an inflation direction of inflation of bladders104. Additionally, or alternatively, bladders104may include areas or patterns of relatively thinner and relatively thicker material or scrim plies, which may be configured to control an inflation direction of inflation of bladders104.

In some examples, a mold surface of bladders104that is configured to contact article101may include a release agent. The release agent may include a material or coating configured to facilitate release of article101from bladders104after drying and/or curing the slurry. For example, bladders104may be at least partially formed from, at least partially coated with, or at least partially formed from and at least partially coated with one or more materials that are hydrophobic relative to the slurry to facilitate release of article101. Materials that are hydrophobic relative to the slurry may include, but are not limited to, polytetrafluoroethylene, fluorinated ethylene propylene, perfluoroalkoxy, polyvinylidene fluoride, ethylene tetrafluoroethylene, ethylene chlorotrifluoroethylene, tetrafluoroethylene perfluoromethylvinylether, terpolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, polychlorotrifluoroethylene, or polytetrafluoroethylene. Additionally, or alternatively, bladders104may be at least partially coated with one or more materials that may be melted after drying and/or curing the slurry to facilitate release of article101. Materials that may be melted after drying and/or curing the slurry may include, but are not limited to, waxes (e.g., ancillary wax, runner wax, sprue wax, or other casting waxes), low melting point polymers (e.g., polymers having a melting point less than about 200° C., or less than about 100° C.), or low glass transition temperature polymers (e.g., polymer having a melting point less than about 200° C., or less than about 100° C.).

Computing device106may be configured to control slurry reservoir108, vacuum pump110, and/or fluid reservoir112to perform a slurry infiltration process. For example, computing device106may be operatively coupled (e.g., via one or more wired or wireless connections) with one or more components of system100to send data to and/or receive data from any of mold body102, cavity103, bladders104, slurry reservoir108, vacuum pump110, and/or fluid reservoir112. Computing device106may include, for example, a smartphone, a tablet computer, a laptop computer, a desktop computer, or the like. Computing device106may include various types of fixed function and/or programmable processing circuitry or other hardware, including, but not limited to, microprocessors, controllers, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or equivalent discrete or integrated logic circuitry, as well as combinations of such components. The term “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry. In some examples, computing device106includes hardware that can be configured to execute firmware and/or software that sets forth one or more of the techniques described herein. For example, computing device106may be configured to implement functionality, process instructions, or both for execution of processing instructions stored within one or more storage components.

After infiltration, the slurry may be dried to remove the carrier material, leaving behind the solid particles of the slurry. Bladders104may remain inflated during drying, or the inflation of bladders104may be adjusted during drying (e.g., bladders104may be fully or partially deflated or an inflation of bladders104may be increased). In some examples, the dried slurry may form a bladder cast surface layer on article101. A thickness of the bladder cast surface layer may be within a range from about 0 micrometers to about 1 millimeter, such as less than about 125 micrometers.

FIG.2is a conceptual diagram illustrating cross-sectional view of a portion of system100and article101that includes slurry210and CMC substrate216. CMC substrate216includes reinforcement material220, which defines inner spaces218. In some examples, reinforcement material220may include continuous fibers, chopped fibers, woven fibers, or combinations thereof. The composition of reinforcement material220may include aluminum oxide, aluminosilicate, carbon, carbon nitride, metal oxides, mullite, silicon carbide, silicon carbon nitride, silicon nitride, silicon oxide, or combinations thereof. In some examples, reinforcement material220may include continuous monofilament or multifilament fibers of one or more of the materials. Although reinforcement material220is illustrated as including non-woven fibers, in some examples, reinforcement material220may be include one or more layers of woven fibers. For example, reinforcement material220may include a lay-up of two or more woven fiber (e.g., fabric) layers. In some examples, reinforcement material220may include a lay-up of one or more woven fiber layer and one or more non-woven fiber layers.

The fibers of reinforcement material220may include an optional fiber interface material. The optional fiber interface material may rigidize the fibers, densify CMC substrate216, or both, prior to the infiltration of the slurry. Example optional fiber interface materials include pyrolytic carbon, boron nitride, or other materials suitable for coating reinforcement material220. In some examples, the optional fiber interface material may be deposited on the reinforcement material220using any suitable technique such as, for example, chemical vapor infiltration (CVI) or chemical vapor deposition (CVD).

Inner spaces218(e.g., pores) of CMC substrate216between reinforcement material220may be infiltrated with slurry210that includes carrier material212and solid particles214. Carrier material212may include at least one solvent compatible with reinforcement material220, the optional interface material, and/or solid particles214. In some examples, carrier material212may include water, ethanol, isopropyl alcohol, methyl ethyl ketone, toluene, or the like. During the drying of slurry210, carrier material212may be substantially removed (e.g., removed or nearly removed) from article101, leaving behind the solid contents of slurry210(e.g. solid particles214).

Solid particles214may include any suitable material configured to at least partially fill inner spaces218In some examples, solid particles214may include aluminum oxide, aluminosilicate, boron carbide, carbon, ceramics, metal oxides, molybdenum carbide, silicon carbide, silicon nitride, silicon oxide, or combinations thereof. Solid particles214may include particles having an average particle diameter sufficiently small to allow the particles to infiltrate inner spaces218(e.g., open pores) of CMC substrate216. For example, solid particles14may have an average particle diameter less than about 50 micrometers, such as less than about 20 micrometers. In some examples, solid particles214may include particles having a uniformly or a non-uniformly distributed particle size. In some examples, solid particles214may be selected to include substantially the same (e.g., the same or nearly the same) components used to form reinforcement material220. In this way, solid particles214may reduce the stress exerted on CMC substrate216as a result of differences between a thermal expansion coefficient of reinforcement material220and a thermal expansion coefficient of solid particles214.

In some examples, slurry210may include one or more optional additives. The additives may be used to control the properties of slurry210. For example, the one or more optional additives may include matrix precursors or other reactive elements that react with silicon metal or silicon alloy (e.g., silicon carbide or silicon nitride) during a melt infiltration process (e.g., after drying of slurry210) and contribute to the solid materials included in inner spaces218. In some examples, the one or more optional additives may include a binder (e.g. polyethylene glycol, acrylate co-polymers, latex co-polymers, polyvinyl pyrrolidone co-polymers, polyvinyl butyral, or the like), a dispersant (e.g., ammonium polyacrylate, polyvinyl butyral, a phosphate ester, polyethylene imine, BYK110(available from Byk USA, Inc., Wallingford Connecticut), or the like), or other materials configured to control a dispersion of solid particles214in slurry210. In some examples, other additives such as a surfactant (e.g., ethoxylated acetylenicgemini surfactant) may be included in slurry210to improve wetting of slurry210. The selection and amount of the one or more optional additive components may depend on the intended application for article101.

In some examples, a composition of slurry210may include about 35% to about 65% by weight carrier material, about 35% to 65% by weight of solid particles214, and up to 10% percent by weight optional additives (e.g., up to 8% by weight carbon material, up to 2% by weight surfactant, or the like).

As illustrated inFIG.2, slurry210including solid particles214may infiltrate into at least some inner spaces218of CMC substrate216. In some examples, surface224(e.g., illustrated as a dashed line) of CMC substrate216may be textured or uneven. For example, surface224may include multiple peaks (e.g., peak206) and valleys (e.g., valley208) due to a fiber structure of reinforcement material220.

After introduction of slurry210into cavity114and during inflation of bladders104, a mold surface204of bladders104may contact the textured surface224of CMC substrate216. For example, mold surface204of bladder104B may contact peak106of CMC substrate216. Slurry210may fill the void230defined by mold surface204and valleys208. By contacting the multiple peaks of surface224, the mold surfaces (e.g., mold surface204) of bladders104may define a more uniform or flat surface226relative to a textured or uneven surface224of CMC substrate216. In this way, slurry infiltration using bladders104may improve surface finish (i.e., provide a bladder cast finish of surface226) relative to slurry infiltration processes without bladders104. Additionally, or alternatively, the increased smoothness of surface226may reduce post-processing steps, such as, for example, removing surface material (e.g. solid particles14of the dried slurry) to establish a substantially planar (e.g., planar or nearly planar) surface.

In some examples, one or more second slurries may be applied to surface226to further increase the surface smoothness of article101. The one or more second slurries also may further protect the underlying reinforcement material220as compared to applying only a single slurry to CMC substrate216. For example, subsequent machining of surface224may cause reinforcement material220(e.g., fibers) to become partially exposed or damaged, which may affect the durability of article101. The one or more second slurries may provide a sufficient coverage to protect reinforcement material220during subsequent machining, such as removing high spots in the one or more second slurries. In some examples, a second slurry may be applied in the same manner described with respect to slurry210.

After drying and/or curing slurry210, a melt infiltration process may increase the overall density of article101, e.g., by filling voids between particles of solid particles214. In some examples, the molten metal infiltrant may include Si metal or Si metal alloy, B metal or B metal alloy, Al metal or Al metal alloy, Y metal or Y metal alloy, Ti metal or Ti metal alloy, Zr metal or Zi metal alloy, or the like. In some examples, the molten metal infiltrant includes Si metal or Si metal alloy (e.g., Si and BN powder).

In some examples, article101may also include one or more optional outer coatings applied to outer surface layer including, for example, a bond coat, an environmental barrier coating (EBC), an abradable coating layer, a calcia-magnesia-aluminosilicate (CMAS)-resistant layer, or the like. In some examples, a single layer of the one or more optional outer coatings may perform two or more of these functions.

FIG.3is a flow diagram illustrating an example technique for forming an article via slurry infiltration using inflatable bladders. While the technique is described with reference to system100and article101illustrated inFIGS.1and2, in other examples, the technique may be used to form other articles, or article101may be formed using a technique different than that described in reference toFIG.3.

Although not illustrated inFIG.3, the technique may include forming CMC substrate216. CMC substrate216may be formed using any suitable fiber preform manufacturing technique including, but not limited to, arranging of chopped fibers, forming non-woven fabrics, forming woven fabrics, lay-up of fabrics, filament winding, braiding, and/or knotting. Additionally or alternatively, CMC substrate216may be acquired in prefabricated form.

The technique illustrated inFIG.3includes infiltrating a CMC substrate216with slurry210including carrier material212and solid particles214(302). Slurry210may be applied to CMC substrate216using any suitable technique that allows solid particles214to at least partially infiltrate the inner spaces218(e.g., pores) of CMC substrate216. In some examples, infiltrating CMC substrate216may include placing CMC substrate216into cavity114, sealing mold body102, and introducing slurry210into cavity114to surround CMC substrate216. Introducing slurry210into cavity114may include controlling, by computing device106, slurry reservoir108to introduce slurry210into cavity114. In other examples, infiltrating CMC substrate216may include applying slurry210to CMC substrate (e.g., by dip coating, spraying, brushing, or the like) prior to placing CMC substrate into mold body102.

In some examples, the technique may include drawing a vacuum within cavity114. For example, drawing a vacuum may include controlling, by computing device106, vacuum pump110to draw a vacuum (e.g., relative to atmospheric pressure) within cavity114. Drawing the vacuum may improve infiltration of slurry210into inner spaces118of CMC substrate116by removing at least some gases from inner spaces118to reduce pressure gradients that may form within inner spaces118during infiltration of slurry210.

After introducing slurry210into cavity114, the technique illustrated inFIG.3includes inflating at least one bladder of bladders104(304). In some examples, inflating bladders104may include controlling, by computing device106, fluid reservoir112to inflate one or more of bladders104. Bladders104may be inflated at a selected rate, inflated to a selected pressure, or both. The selected rate and/or selected pressure may be determined based on a mechanical stability of CMC substrate216. For example, the selected rate and/or the selected pressure may be less than an inflation rate and/or an inflation pressure that would cause damage to or deformity of CMC substrate216.

In some examples, inflating bladders104may include simultaneously inflating bladders104. In some examples, inflating bladders104may include selectively inflating one or more first bladders and subsequently inflating one or more second bladders to prevent or reduce damage or deformity of CMC substrate216during inflation of bladders104. For example, bladder104A may be at least partially inflated to contact interior surfaces of tips119of CMC substrate116and bladder104D may be at least partially inflated to contact exterior surface of base117of CMC substrate116. Subsequently, bladders104B and104C may be at least partially inflated to contact the exterior surfaces of tips119and interior surface of base117. Each of bladders104A and104D, and bladders104B and104C, may be inflated at a selected rate and to a selected pressure to prevent or reduce movement of CMC substrate within cavity114, to prevent or reduce damage or deformity of base117and/or tips119, or both. Other inflation sequences maybe used depending on a geometry of CMC substrate216or other factors that may affect the position or orientation of CMC substrate216during inflation of bladders104or that may affect the rate or extent of slurry infiltration into CMC substrate216.

After inflating bladders104, the technique illustrated inFIG.3include drying and/or curing slurry210(306). The drying and/or curing may be conducted in any suitable manner. In some examples, the infiltrated CMC substrate216can be dried at room temperature under vacuum at about 133 Pa, or may be dried at ambient pressure at a temperature of up to about 150° C. In some examples, drying and/or curing slurry210may remove at least a portion of carrier material212, leaving solid particles214within at least some inner spaces218of CMC substrate216. In some examples, drying and/or curing slurry210may result in a bladder cast surface226.

In some examples, an inflation of one or more bladders104may be adjusted during drying and/or curing. For example, a pressure of bladders104may be increased one or more times at one or more increments of pressure during drying and/or curing. Increasing the pressure of bladders104during drying and/or curing may affect a surface finish of surface226by urging solid particle214toward surface224of CMC substrate216, further urge infiltration of slurry210into inner spaces218, or both. Additionally, or alternatively, a pressure of bladders104may be decreased one or more times at one or more increments of pressure during drying and/or curing. Decreasing the pressure of bladders104may affect a surface finish of surface226by enabling separation of solid particles214at or near surface226(e.g., relative to surface224of CMC substrate216), facilitate release of article101after drying, or both.

After drying and/or curing the slurry, the technique illustrated inFIG.3includes deflating bladders104(308). In some examples, deflating bladders104may include heating mold body102and/or article101to melt a release agent, such as a wax. After bladders are deflated, article101may be removed from mold body102.

In some examples, the technique may include infiltrating article101with a molten infiltrant to form a composite CMC article. The molten infiltrant may include a molten metal or molten alloy infiltrant. The molten metal or molten alloy infiltrant may wick between reinforcement material220and/or solid particles214to occupy at least some interstices remaining within inner spaces218after drying and/or curing the slurry. In some examples, the melt infiltration process may densify the resultant composite CMC article to define an average porosity of less than about 5%, or less than about 3%, or less than about 1%.

In some examples, the molten metal or molten alloy infiltrant may include Si metal or Si metal alloy, B metal or B metal alloy, Al metal or Al metal alloy, Y metal or Y metal alloy, Ti metal or Ti metal alloy, Zr metal or Zi metal alloy, or the like. In some examples, the molten metal infiltrant includes Si metal or Si metal alloy (e.g., Si and BN powder). In some examples, the temperature for metal alloy infiltration such as Si metal infiltration is between about 1400° C. and about 1500° C. Under these conditions, the duration of the infiltration may be between about 15 minutes and about 4 hours, or between about 20 minutes and about 60 minutes. The melt infiltration process may be carried out under vacuum, or in inert gas under atmospheric pressure to limit evaporation losses.

In some examples, the technique may include machining surface226of article101. In some examples, machining surface226may be performed before or after melt infiltration. Machining surface226may remove excess material (e.g., solid particles214) to define a contact surface for contacting another component or material (e.g., one or more optional coatings). The machining may include, for example, milling, turning, shaping, planing, grinding, polishing, tumbling, grit blasting, etching, or the like.

In some examples, after melt infiltration and/or machining, the technique may include applying one or more optional coatings such as, for example, a bond coat, an EBC, a TBC, an abradable layer, a CMAS-resistant layer, or the like using one or more of the techniques discussed above.

The techniques described in this disclosure may be implemented, at least in part, in hardware, software, firmware or any combination thereof. For example, various aspects of the described techniques may be implemented within one or more processors, including one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. The term “processor” or “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry. A control unit including hardware may also perform one or more of the techniques of this disclosure.

Such hardware, software, and firmware may be implemented within the same device or within separate devices to support the various operations and functions described in this disclosure. In addition, any of the described units, modules or components may be implemented together or separately as discrete but interoperable logic devices. Depiction of different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be realized by separate hardware or software components. Rather, functionality associated with one or more modules or units may be performed by separate hardware or software components, or integrated within common or separate hardware or software components.

The techniques described in this disclosure may also be embodied or encoded in a computer-readable medium, such as a computer-readable storage medium, containing instructions. Instructions embedded or encoded in a computer-readable medium may cause a programmable processor, or other processor, to perform the method, e.g., when the instructions are executed. Computer-readable media may include non-transitory computer-readable storage media and transient communication media. Computer readable storage media, which is tangible and non-transitory, may include random access memory (RAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), flash memory, a hard disk, a CD-ROM, a floppy disk, a cassette, magnetic media, optical media, or other computer-readable storage media. It should be understood that the term “computer-readable storage media” refers to physical storage media, and not signals, carrier waves, or other transient media.

Various examples have been described. These and other examples are within the scope of the following claims.