Patent ID: 12186820

Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements.

DETAILED DESCRIPTION

Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows and “downstream” refers to the direction to which the fluid flows.

As used herein, a “ceramic component” is a component formed of ceramic-based materials. Ceramic-based materials encompass both homogeneous ceramic materials as well as ceramic composite materials, such as Ceramic Matrix Composite (CMC) materials. CMC materials generally include a ceramic fiber reinforcement material embedded in a ceramic matrix material. As one example, the ceramic fiber reinforcement material and the ceramic matrix material of a CMC material can both be formed of SiC. SiC/SiC CMC components are particularly suitable for high-temperature applications, such as for high-temperature components of aviation gas turbine engines and land-based gas turbine engines used in the power generation industry. SiC fibers can also been used as a reinforcement material for a variety of other ceramic matrix materials, such as, without limitation, titanium carbide (TiC), silicon nitride (Si3N4), and alumina (A1203).

Aspects of the present disclosure are directed to methods of Electrical Discharge Machining (EDM) ceramic components, such as CMC components for gas turbine engines. Particularly, disclosed herein is a contact matrix or matrix of electrical contacts that can be positioned between a CMC component and a grounding structure to facilitate efficient and effective electrical grounding of the CMC component during EDM of the CMC component. The contact matrix includes a plurality of contacts that contact or otherwise engage the CMC component. The electrically conductive contacts can be coupled with a backbone. The contacts can be directly connected or attached to the backbone or they can be coupled thereto, e.g., by means of a pin housing and/or a spring. The backbone can be electrically conductive and can be rigid or flexible. Further, the backbone can be straight or can be contoured complementary to the CMC component and/or the grounding structure.

Further, the contacts can be compliant and pressurized contacts such that they engage the rigid CMC component with spring-like action. In this way, numerous contacts can be biased into engagement with the CMC component and/or the grounding structure to accommodate the irregularity of the rigid surfaces. As one example, the compliant and pressurized contacts can be electrically conductive bristles. Each electrically conductive bristle can extend from a bristle stem to a bristle tip. The elasticity in a compressed bristle stem can exert contact pressure of the bristle tip to the rigid CMC surface. In this way, the bristles can maintain engagement with the rigid CMC component during EDM. As another example, the compliant and pressurized contacts can be electrically conductive spring-loaded pins. The spring-loaded pins can include an electrically conductive pin and a compressible spring. Compression of the spring behind the pin can exert contact pressure of the pin to the rigid CMC surface. The compressed spring maintains the pin into engagement with the rigid CMC component during EDM.

Notably, the contacts can provide pathways for electrical current to pass from the contact matrix to the CMC component or vice versa. Accordingly, the contacts are in electrical conduction to the CMC component when they are biased into engagement with the CMC component. The contact matrix can also be in electrical conduction to a grounding structure, such as a fixture of an EDM system. In this way, electrical current can be passed from the grounding structure to the contact matrix and then from the contact matrix to the CMC component during EDM. It is also possible for electrical current to be passed from the CMC component to the contact matrix and then from the contact matrix to the grounding structure.

Advantageously, the contact matrix can significantly increase the number of pathways in which the CMC component can be electrically grounded, which can lead to more efficient and effective electrical grounding of the CMC component during EDM. These numerous pathways increase flow capacity of electrical current to allow EDM at high power. With better electrical grounding, a smoother burn or sparking without contact overheat or arcing can be achieved during EDM, which can result in reduced cycle times and scrap and minimizes the risk of broken tool electrodes, among other benefits.

FIG.1provides a schematic cross-sectional view of a gas turbine engine in accordance with one example embodiment of the present subject matter. For the depicted embodiment ofFIG.1, the gas turbine engine is a high-bypass turbofan jet engine10, referred to herein as “turbofan10.” As shown inFIG.1, the turbofan10defines an axial direction A (extending parallel to a longitudinal centerline12provided for reference), a radial direction R, and a circumferential direction extending in a plane orthogonal to the axial direction A three hundred sixty degrees around the longitudinal centerline12.

The turbofan10includes a fan section14and a core turbine engine16disposed downstream from the fan section14. The core turbine engine16includes a substantially tubular outer casing18that defines an annular core inlet20. The outer casing18encases, in serial flow relationship, a compressor section including a booster or low pressure (LP) compressor22and a high pressure (HP) compressor24; a combustion section26; a turbine section including a high pressure (HP) turbine28and a low pressure (LP) turbine30; and a jet exhaust nozzle section32. A high pressure (HP) shaft or spool34drivingly connects the HP turbine28to the HP compressor24. A low pressure (LP) shaft or spool36drivingly connects the LP turbine30to the LP compressor22.

The fan section14includes a variable pitch fan38having a plurality of fan blades40coupled to a disk42in a spaced apart manner. As depicted, the fan blades40extend outward from the disk42generally along the radial direction R. Each fan blade40is rotatable relative to the disk42about a pitch axis P by virtue of the fan blades40being operatively coupled to a suitable actuation member44configured to collectively vary the pitch of the fan blades40in unison. The fan blades40, disk42, and actuation member44are together rotatable about the longitudinal axis12by LP shaft36.

Referring still toFIG.1, the disk42is covered by a rotatable front nacelle48aerodynamically contoured to promote an airflow through the plurality of fan blades40. Additionally, the fan section14includes an annular fan casing or outer nacelle50that circumferentially surrounds the fan38and/or at least a portion of the core turbine engine16. The nacelle50may be supported relative to the core turbine engine16by a plurality of circumferentially-spaced outlet guide vanes52. Moreover, a downstream section54of the nacelle50may extend over an outer portion of the core turbine engine16so as to define a bypass airflow passage56therebetween.

During operation of the turbofan10, a volume of air58enters the turbofan10through an associated inlet60of the nacelle50and/or fan section14. As the volume of air58passes across the fan blades40, a first portion of the air58as indicated by arrows62is directed or routed into the bypass airflow passage56and a second portion of the air58as indicated by arrow64is directed or routed into the annular core inlet20and into the LP compressor22. The pressure of the second portion of air64is then increased as it is routed through the high pressure (HP) compressor24and into the combustion section26, where it is mixed with fuel and burned to provide combustion gases66.

The combustion gases66are routed through the HP turbine28where a portion of thermal and/or kinetic energy from the combustion gases66is extracted via sequential stages of HP turbine stator vanes68that are coupled to the outer casing18and HP turbine rotor blades70that are coupled to the HP shaft or spool34, thus causing the HP shaft or spool34to rotate, thereby supporting operation of the HP compressor24. The combustion gases66are then routed through the LP turbine30where a second portion of thermal and kinetic energy is extracted from the combustion gases66via sequential stages of LP turbine stator vanes72that are coupled to the outer casing18and LP turbine rotor blades74that are coupled to the LP shaft or spool36, thus causing the LP shaft or spool36to rotate, thereby supporting operation of the LP compressor22and/or rotation of the fan38.

The combustion gases66are subsequently routed through the jet exhaust nozzle section32of the core turbine engine16to provide propulsive thrust. Simultaneously, the pressure of the first portion of air62is substantially increased as the first portion of air62is routed through the bypass airflow passage56before it is exhausted from a fan nozzle exhaust section76of the turbofan10, also providing propulsive thrust. The HP turbine28, the LP turbine30, and the jet exhaust nozzle section32at least partially define a hot gas path78for routing the combustion gases66through the core turbine engine16.

It will be appreciated that, although described with respect to turbofan10having core turbine engine16, the present subject matter may be applicable to other types of turbomachinery. For example, the present subject matter may be suitable for use with or in turboprops, turboshafts, turbojets, industrial and marine gas turbine engines, and/or auxiliary power units.

In some embodiments, components of turbofan10can be formed of a composite material. For example, components within hot gas path78, such as components of combustion section26, HP turbine28, and/or LP turbine30, can be formed of a CMC material, which is a non-metallic material having high temperature capability. For instance, turbine blades and turbine nozzles can be formed of CMC materials. Other components of turbine engine10also may be formed from CMC materials or other suitable composite materials.

Exemplary matrix materials for such CMC components can include silicon carbide, silicon, silica, alumina, or combinations thereof. Ceramic fibers can be embedded within the matrix, such as oxidation stable reinforcing fibers including monofilaments like sapphire and silicon carbide (e.g., Textron's SCS-6), as well as rovings and yarn including silicon carbide (e.g., Nippon Carbon's NICALON®, Ube Industries' TYRANNO®, and Dow Corning's SYLRAMIC®), alumina silicates (e.g., Nextel's 440 and 480), and chopped whiskers and fibers (e.g., Nextel's 440 and SAFFIL®), and optionally ceramic particles (e.g., oxides of Si, Al, Zr, Y, and combinations thereof) and inorganic fillers (e.g., pyrophyllite, wollastonite, mica, talc, kyanite, and montmorillonite). CMC materials may have coefficients of thermal expansion in the range of about 1.3×10−6in/in/° F. to about 3.5×10−6in/in/° F. in a temperature range of approximately 1000-1200° F.

FIG.2provides a perspective view of a turbine nozzle segment80according to an exemplary embodiment of the present subject matter. For this embodiment, the turbine nozzle segment80is formed of a CMC material, such as one or more of the CMC materials noted above. The turbine nozzle segment80is one of a number of nozzle segments that when connected together form an annular nozzle assembly of a gas turbine engine, such as e.g., the turbofan10ofFIG.1. The nozzle segment80includes vanes82, such as e.g., stator vanes68of the turbofan10ofFIG.1. Each vane82or airfoil and extends between an outer and inner band84,86. Notably, the vanes82define a plurality of cooling holes88. Cooling holes88provide film cooling to improve the thermal capability of the vanes82. The cooling holes88can be fluidly connected to one or more fluid passageways that extend internally through the vanes82. The cooling holes88as well as other features of the turbine nozzle segment80can be machined via an EDM process.

FIG.3provides a schematic cross-sectional view of a CMC component200undergoing EDM. For instance, the CMC component200can be the turbine nozzle segment80ofFIG.2and the feature being machined into the CMC component200via EDM can be one of the cooling holes88. It will be appreciated that other CMC components, or more generally ceramic components, can be machined via EDM using the inventive concepts disclosed herein.

Generally, to machine a feature into the CMC component200, an electrode tool of an EDM system is guided proximate to the CMC component200submerged in a dielectric fluid. A pulse generator of the EDM system causes the voltage between the electrode tool and the CMC component200to increase, which ultimately causes electrical discharges or sparks that remove material from the CMC component200. A series of rapidly recurring electrical discharges are made until the desired feature in the CMC component200is formed. For safe and effective EDM operation and handling of the CMC component200, it is necessary to electrically ground the CMC component200during EDM for the efficient conduction of electrical current with minimum contact resistance. In accordance with the inventive aspects of the present subject matter, a contact matrix100is provided to facilitate efficient and effective grounding of the CMC component200during EDM.

As depicted inFIG.3, the contact matrix100is positioned such that it engages the CMC component200and a grounding structure300, e.g., to facilitate electrical grounding during the EDM process. The grounding structure300can be a metallic fixture operable to hold the CMC component200during EDM, for example. Generally, the contact matrix100decreases the electrical contact resistance or the Schottky barrier between the CMC component200and the grounding structure300, which facilitates efficient and effective electrical conduction between the CMC component200and the grounding structure300during EDM.

The contact matrix100includes a backbone110and a plurality compliant and pressurized contacts120. The backbone110and the compliant and pressurized contacts120are both formed of an electrically conductive material. The backbone110can be any suitable shape. For instance, the backbone110can have a rectangular shape as shown inFIG.3. In some embodiments, the backbone110can have a helical shape. Accordingly, the backbone110can be a helical wire rope in some embodiments. In some embodiments, the backbone110can be a rigid electrically conductive member. In other embodiments, the backbone110can be a flexible electrically conductive member. Further, in some embodiments, the backbone110can be a straight member. In other embodiments, the backbone110can be a curved or arcuate member.

For the depicted embodiment ofFIG.3, the electrically conductive backbone110is the electrically conductive member of the contact matrix100that engages the grounding structure300. As this is a conductive-to-conductive material interface (e.g., metal-to-metal), the Schottky barrier is not present and electrical current can flow with low contact resistance from the backbone110to the grounding structure300even despite the limited number of contact points CG1, CG2between the irregular surface of the backbone110and the irregular surface of the grounding structure300. In other embodiments, as will be explained further herein, the electrically conductive member of the contact matrix100that engages the grounding structure300can be other suitable members, such as a set of the electrically conductive contacts120.

Each of the electrically conductive contacts120are connected to and extend outward from the backbone110. In this way, the backbone110acts as the central hub of the contact matrix100. The contact matrix100can have any suitable number of contacts120. Accordingly, the contacts120engaged with the CMC component200can multiply the capacity of surface current flow of the CMC component200by N times, wherein N is the number of contacts of the contact matrix100engaging the CMC component200. For instance, as shown inFIG.3, each contact120engaging the irregular surface of the CMC component200creates an electrical conduction pathway or contact point between the CMC component200and the contact matrix100. As depicted, a first contact120engaging the CMC component200creates a first contact point C1or first conduction pathway, a second contact120engaging the CMC component200creates a second contact point C2or second conduction pathway, and so on to the Nth contact120that engages the CMC component200to create an Nth contact point CN or Nth conduction pathway between the CMC component200and the contact matrix100.

For this embodiment, the contacts120are compliant in that they may each plastically and/or elastically deform or bend when engaged with a component or structure. For the depicted embodiment ofFIG.3, the contacts120include a plurality of electrically conductive bristles. The bristles can be steel bristles, for example. As shown, the contacts120, or bristles in this embodiment, deform or bend when they engage the CMC component200. The deformation of the bristles causes the bristles to engage the CMC component200with spring-like action such that the bristles are biased into contact with the CMC component200. Stated another way, the contacts120apply pressure to the CMC component200. Contact pressure is present between the bristle tips and CMC surface. This ensures engagement of the contacts120with the surface of the CMC component200during EDM. With the contact matrix100engaged in electrical conduction to the grounding structure300and the contacts120engaged with the CMC component200during EDM, electrical current can effectively pass from the grounding structure300to the contact matrix100and then to the CMC component200via the contacts120or vice versa. It is typical for the electrical current to flow from the grounding structure300to the CMC component200via the contact matrix100.

FIG.4provides a close-up schematic view of one contact120of the contact matrix100ofFIG.3engaging the CMC component200. As shown, the contact120has a stem or first end122and a tip or second end124. The first end122is connected to the backbone110of the contact matrix100and the second end124is not connected to the backbone110. When the contact matrix100is moved into position, e.g., between the CMC component200and the grounding structure300, the contact120engages the CMC component200. Consequently, the contact120transitions from a relaxed state (represented by the dashed line120A) to an engaged state (represented by the solid line120B). The contact matrix100is positioned such that the distance between the backbone110and the CMC component200is less than the length that the contact120extends outward from the backbone110in its relaxed state. Accordingly, when the contact120engages the CMC component200and deforms, the contact120engages the CMC component200with spring-like action, which provides contact pressure for contact reliability.

Particularly, in the engaged state, the contact120can undergo both plastic and elastic deformation. For instance, a portion of the contact120extending from the first end122to some point outward of the first end122may plastically deform (i.e., permanent deformation) and a portion from the point outward to the second end124may elastically deform (i.e., non-permanent deformation). The portion of the contact120that elastically deforms may apply pressure or a force on the CMC component200, which thus biases the contact120into engagement with the CMC component200. The biased engagement of the contact120ofFIG.4with the CMC component200maintains the contact120and the CMC component200in electrical conduction during EDM. Thus, a reliable electrical conduction pathway for electricity to flow from the contact matrix100to the CMC component200is provided during EDM. It will be appreciated that all or some of the other contacts120of the contact matrix100ofFIG.3can engage the CMC component200in a similar manner as described above with respect to the contact120ofFIG.4.

In some embodiments, the contacts120of the contact matrix100can be configured in a different manner than those shown inFIGS.3and4. For instance, one or more of the contacts120can be configured as shown inFIG.5. InFIG.5, the electrically conductive contact120has a first end122and a second end124. For this embodiment, the first end122and the second end124are connected to the backbone110of the contact matrix100. When the contact matrix100is moved into position, e.g., between the CMC component200and the grounding structure300, the contact120engages the CMC component200. As a result, the contact120transitions from a relaxed state (represented by the dashed line120C) to an engaged and compressed state (represented by the solid line120D). The contact matrix100is positioned such that the distance between the backbone110and the CMC component200is less than the length that the contact120extends outward from the backbone110to its apex126. Accordingly, when the contact120engages the CMC component200and deforms, the contact120engages the CMC component200with spring-like action, which provides contact pressure for contact reliability.

FIG.6provides a schematic view of another example configuration of the contact matrix100. For this embodiment, the plurality of electrically conductive contacts120include a first set130of electrically conductive compliant contacts and a second set140of electrically conductive compliant contacts. The compliant contacts of the first set130alternate with the compliant contacts of the second set140in this example embodiment. As shown, the electrically conductive compliant contacts of the first set130extend outward from the backbone110a first predetermined length L1in a first direction D1. The electrically conductive compliant contacts of the second set140extend outward from the backbone110a second predetermined length L2in the first direction D1. Notably, the first predetermined length L1is greater than the second predetermined length L2. In other embodiments, the plurality of electrically conductive contacts120can include more than two sets of compliant contacts having predetermined lengths. By varying the length of the compliant contacts of the sets, the spring action applied to the CMC component200by the compliant contacts can be varied. Further, varying the length of the compliant contacts of the sets allows for additional margin in positioning the contact matrix100relative to a CMC component (and in some instances, a metallic grounding structure).

With reference now toFIGS.7and8, another example configuration of the contact matrix100is provided. For this embodiment, the plurality of electrically conductive contacts120include a first set130of electrically conductive compliant contacts and a second set140of electrically conductive compliant contacts. The compliant contacts of the first set130extend from the backbone110along a first direction D1and engage the CMC component200, e.g., as shown inFIG.8. The compliant contacts of the second set140extend from the backbone110along a second direction D2and engage the grounding structure300, e.g., as shown inFIG.8. Accordingly, for this embodiment, the electrically conductive member of the contact matrix100that is in electrical conduction to the grounding structure300is the second set140of compliant contacts. In some embodiments, the second direction D2is opposite the first direction D1. In other embodiments, the second direction D2is not opposite the first direction D1.

As shown, the first and second sets130,140of compliant contacts can have different predetermined lengths similar to the embodiment shown inFIG.6. However, it will be appreciated that the compliant contacts of the first and second sets130,140of the embodiment ofFIGS.7and8can have all the same length or can have compliant contacts having different lengths randomly arranged with respect to the backbone110.

FIG.9provides a schematic view of another example configuration of the contact matrix100. For this embodiment, the backbone110is curved or contoured. In this manner, the contacts120can contour to the surface or surfaces of the CMC component200and/or the grounding structure300. This can provide a greater surface area of contact, which can ultimately effectively ground the CMC component200during EDM. The backbone110can be contoured to any suitable shape. In some embodiments, the backbone110is flexible such that the contact matrix100can be manipulated relative to the CMC component200and/or grounding structure300. In other embodiments, the backbone110is preformed into the desired contour shape and is rigid.

With reference now toFIGS.10and11,FIG.10provides a schematic view of another example configuration of the contact matrix100.FIG.11provides a close-up view of one of the contacts120of the contact matrix100ofFIG.10. For this embodiment, the plurality of electrically conductive contacts120are spring-loaded pins. As will be explained below, each spring-loaded pin includes an electrically conductive pin and a spring connected thereto. The spring of a given spring-loaded pin provides the compliance to account for the surface irregularity of the CMC surface. The spring also provides the contact pressure for maintaining the pin in contact with the irregular and rigid CMC surface for contact reliability.

As shown best inFIG.11, the depicted contact120, or electrically conductive pin150in this example embodiment, is connected with a spring152. The spring152extends between a first end154and a second end156. The pin150is connected with the spring152at its first end154. Particularly, the first end154of the spring152is received within a recess defined by the pin150. The pin150can be any suitable shape. Further, the pin150and the spring152are enclosed within a housing158. The housing158can be formed of an electrically conductive material. The housing158can be connected to or formed integrally with the backbone110. The spring152can contact or sit relatively flush with the base of the housing158or the backbone110at its second end156. The housing158includes one or more stops160that retain the pin150relative to the housing158. The spring152can be coupled with a post162. The post162can assist in maintaining the orientation of the spring152and the pin150. Each contact120in the depicted embodiment ofFIGS.10and11can be configured in the same manner shown inFIG.11.

Notably, for this embodiment, the pin150is movable along a first direction D1. Particularly, when the pin150is not engaged with a surface of the CMC component200(or in some instances a metallic grounding structure), the spring152is in a relaxed state. When the contact matrix100is moved into position such that the pin150engages the CMC component200, the CMC component200applies a force on the pin150. The applied force on the pin150causes the spring152to compress, and consequently, the pin150is moved toward the backbone110of the contact matrix100along the first direction D1. When compressed, the spring152is in a compressed state. The spring152is shown in the compressed state inFIG.11. When compressed, the pin150in turn exerts a force on the CMC component200as the spring152seeks to return to its relaxed state. Thus, the pin150is biased into engagement with the CMC component200. With the contacts120, or spring-loaded pins150in this embodiment, engaged with the CMC component200during EDM, electrical current can effectively pass from the grounding structure300to the contact matrix100and then to the CMC component200via the contacts120. This facilitates efficient and effective grounding of the CMC component200during EDM.

FIG.12provides a schematic view of another example configuration of the contact matrix100. For this embodiment, like the embodiment ofFIGS.10and11, the plurality of electrically conductive contacts120are spring-loaded pins. However, in this embodiment, the backbone110is curved or contoured. In this manner, the contacts120, or spring-loaded pins in this embodiment, can contour or be oriented to the surface or surfaces of the CMC component200and/or the grounding structure. This can provide a greater surface area of contact, which can ultimately effectively ground the CMC component200during EDM. The backbone110can be contoured to any suitable shape. In some embodiments, the backbone110is flexible such that the contact matrix100can be manipulated relative to the CMC component200and/or grounding structure. In other embodiments, the backbone110is preformed into the desired contour shape and is rigid.

In some embodiments, a contact matrix can include different types of compliant contacts. As one example, in some embodiments, a contact matrix can include both bristles and spring-loaded pins.

FIG.13provides a flow diagram of a method (400) of electrical discharge machining a ceramic component according to one example embodiment of the present subject matter. For instance, the method (400) can be used to electrical discharge machine a CMC component, such as the CMC turbine nozzle segment ofFIG.2. Particularly, the method (400) can be used to electrical discharge machine a cooling hole in the CMC turbine nozzle segment ofFIG.2. The method (400) can be used to electrical discharge machine other ceramic components as well.

At (402), the method (400) includes electrical discharge machining a ceramic component while a contact matrix is positioned so that electrically conductive contacts of the contact matrix engage the ceramic component and so that an electrically conductive member of the contact matrix is in electrical conduction to a grounding structure. For instance, as shown inFIG.3, the contact matrix100can be positioned between the ceramic component (the CMC component200) and the grounding structure300. The electrically conductive contacts120of the contact matrix100engage the ceramic component (the CMC component200). The electrically conductive member of the contact matrix100, which inFIG.3is the electrically conductive backbone110, is in electrical conduction to the grounding structure300. Specifically, the backbone110is contacting or otherwise engaged with the grounding structure300. Accordingly, during EDM, electrical current can pass from the grounding structure300to the contact matrix100via the backbone110. The electrical current can then pass from the backbone110to the electrically conductive contacts120of the contact matrix100and to the ceramic component (the CMC component200). The contacts120engaged with the ceramic component provide many electrical grounding pathways for electrical current to flow to the CMC component during EDM, which as noted, can provide efficient and effective grounding of the ceramic component during EDM.

In some implementations of method (400), the electrically conductive contacts are compliant electrically conductive contacts that are biased into engagement with the ceramic component. For instance, in some implementations, the compliant electrically conductive contacts are bristles, e.g., as shown in the embodiments ofFIGS.3through9. In other implementations, the compliant electrically conductive compliant and pressurized contacts are spring-loaded pins, e.g., as shown in the embodiments ofFIGS.10through12.

In some implementations, the electrically conductive member of the contact matrix is one or more of the electrically conductive contacts. In such implementations, the one or more of the electrically conductive contacts engage the grounding structure. As one example, as shown inFIGS.8and9, a first set130of the electrically conductive contacts extend from the backbone110and engage the ceramic component (the CMC component200). In such implementations, the electrically conductive member of the contact matrix100is a second set140of the electrically conductive contacts. As depicted, the electrically conductive contacts of the second set140extend from the backbone110and engage the grounding structure300. In some implementations, as shown inFIG.8, the first set130of the electrically conductive contacts extend from the backbone110in a first direction D1and the second set140of the electrically conductive contacts extend from the backbone110in a second direction D2that is opposite the first direction D1.

In other implementations, the electrically conductive contacts are connected to and extend outward from a backbone. In such implementations, the electrically conductive member of the contact matrix is the backbone, e.g., as shown inFIG.3.

In some implementations, the electrically conductive contacts are coupled with a rigid backbone. In some implementations, the electrically conductive contacts are coupled with a flexible backbone. In some implementations, the electrically conductive contacts are coupled with a backbone that is contoured complementary to the ceramic component, e.g., as shown inFIG.9. In some implementations, the electrically conductive contacts are coupled with a backbone that is straight, e.g., as shown inFIGS.3and8.

In some implementations, at least one of the electrically conductive contacts has a first end and a second end. In such implementations, the first end is connected to a backbone of the contact matrix and the second end is not connected to the backbone, e.g., as shown inFIG.4. In other implementations, at least one of the electrically conductive contacts has a first end and a second end. In such implementations, the first end and the second end are connected to a backbone of the contact matrix, e.g., as shown inFIG.5.

Further, in some implementations, the electrically conductive contacts include a first set of electrically conductive contacts and a second set of electrically conductive contacts. In such implementations, the electrically conductive contacts of the first set extend outward from a backbone a first predetermined length in a first direction and the electrically conductive contacts of the second set extend outward from the backbone a second predetermined length in the first direction, wherein the first predetermined length is greater than the second predetermined length. Such an implementation is depicted in the embodiment ofFIG.6.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Further aspects of the invention are provided by the subject matter of the following clauses:

1. A method, comprising: electrical discharge machining a ceramic component while a contact matrix is positioned so that electrically conductive contacts of the contact matrix engage the ceramic component and so that an electrically conductive member of the contact matrix is in electrical conduction to a grounding structure.

2. The method of any preceding clause, wherein the ceramic component is a ceramic matrix composite component.

3. The method of any preceding clause, wherein the electrically conductive contacts are compliant and pressurized electrically conductive contacts that are biased into pressurized engagement with the ceramic component.

4. The method of any preceding clause, wherein the compliant and pressurized electrically conductive contacts are bristles.

5. The method of any preceding clause, wherein the compliant and pressurized electrically conductive contacts are spring-loaded pins.

6. The method of any preceding clause, wherein the electrically conductive member of the contact matrix is one or more of the electrically conductive contacts, and wherein the one or more of the electrically conductive contacts engage the grounding structure.

7. The method of any preceding clause, wherein the electrically conductive contacts are connected to and extend outward from a backbone, and wherein the electrically conductive member of the contact matrix is the backbone.

8. The method of any preceding clause, wherein a first set of the electrically conductive contacts extend from a backbone and engage the ceramic component.

9. The method of any preceding clause, wherein the electrically conductive member of the contact matrix is a second set of the electrically conductive contacts, and wherein the second set of the electrically conductive contacts extend from the backbone and engage the grounding structure.

10. The method of any preceding clause, wherein the first set of the electrically conductive contacts extend from the backbone in a first direction and the second set of the electrically conductive contacts extend from the backbone in a second direction that is opposite the first direction.

11. The method of any preceding clause, wherein the electrically conductive contacts are coupled with a backbone, and wherein the backbone is flexible.

12. The method of any preceding clause, wherein the electrically conductive contacts are coupled with a backbone, and wherein the backbone is contoured complementary to the ceramic component.

13. A contact matrix for facilitating electrical grounding of a ceramic component undergoing electrical discharge machining, the contact matrix comprising: an electrically conductive backbone; and compliant and pressurized electrically conductive contacts extending outward from the electrically conductive backbone, wherein at least some of the compliant and pressurized electrically conductive contacts are biased into engagement with the ceramic component so that the at least some of the compliant and pressurized electrically conductive contacts are in electrical conduction to the ceramic component, and wherein at least one of the electrically conductive backbone and at least one of the compliant and pressurized electrically conductive contacts are in electrical conduction to a grounding structure.

14. The contact matrix of any preceding clause, wherein the compliant and pressurized electrically conductive contacts are bristles.

15. The contact matrix of any preceding clause, wherein the compliant and pressurized electrically conductive contacts are spring-loaded pins.

16. The contact matrix of any preceding clause, wherein the ceramic component is a ceramic matrix composite component.

17. The contact matrix of any preceding clause, wherein the at least one of the compliant and pressurized electrically conductive contacts is in electrical conduction to the grounding structure.

18. The contact matrix of any preceding clause, wherein the electrically conductive backbone is in electrical conduction to the grounding structure.

19. The contact matrix of any preceding clause, wherein a first set of the compliant and pressurized electrically conductive contacts extend outward from the electrically conductive backbone along a first direction and engage the ceramic component and a second set of the compliant and pressurized electrically conductive contacts extend outward from the electrically conductive backbone along a second direction and engage the grounding structure, wherein the first direction is opposite the second direction.

20. A method, comprising: positioning a contact matrix between a ceramic matrix composite component and a grounding structure, the contact matrix having an electrically conductive backbone and compliant and pressurized electrically conductive contacts extending outward from the electrically conductive backbone; and electrical discharge machining the ceramic matrix composite component while the contact matrix is positioned therebetween so that the compliant and pressurized electrically conductive contacts are biased into pressurized engagement with the ceramic matrix composite component and so that the electrically conductive backbone or at least one of the compliant and pressurized electrically conductive contacts is in electrical conduction to the grounding structure.