Patent Description:
Components are being manufactured from more sophisticated materials. One such material includes CMC materials. Such materials have very beneficial characteristics when facing certain operational situations.

As one example, CMC components are very resistant to heat and, thus, have many applications in high temperature environments. They are being utilized in any number of high temperature locations in gas turbine engines, as an example. However, some applications would benefit from the provision of voids within the CMC body for various reasons. One reason may be the provision of cooling air through channels.

However, the formation of hollows, channels or other voids within a CMC body has been challenging.

It has been proposed to dispose carbon strings within a substrate and then oxidize the carbon away, leaving a void. However, these are very large diameter voids.

A method having the features of the preamble of claim <NUM> is disclosed in <CIT>.

<CIT> discloses a method of producing an internal cavity in a ceramic matrix composite and mandrel therefor.

<CIT> discloses a method of fabricating a composite material blade having internal channels, and a composite material turbine engine blade.

<CIT> discloses a SiC-C/C composite material, uses thereof, and method for producing the same.

<CIT> discloses a method of making ceramic articles having channels therein and articles made thereby.

According to the present invention, there is provided a method of creating a component as claimed in claim <NUM>.

The substrate material may initially include graphite, such that the matrix includes a silicon carbide material.

The voids may be utilized to receive a material subsequent to the formation of the voids.

The template material may be one of fibers, particles, or sheets.

The geared architecture <NUM> may be an epicycle gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about <NUM>:<NUM>.

<FIG> shows a component body <NUM>, which may be a turbine blade as utilized in a gas turbine engine such as the engine in <FIG>. Of course, other components such as heat panels, vanes, combustor liners, seals and the like may benefit from the teachings of this application.

As known, a source of air <NUM> provides cooling air into an airfoil <NUM> formed on the component <NUM>. As shown schematically in <FIG>, there are a plurality of very small voids, cavities or channels <NUM> extending through the component <NUM> and which may be formed by the teachings of this disclosure.

<FIG> shows a first intermediate step to form the component <NUM>. A carbon-containing substrate <NUM> is provided with silicon template materials <NUM>. In non-limiting examples, the carbon-containing substrate can be graphite, amorphous carbon, glassy carbon, carbonaceous material, activated carbon, turbostratic carbon and mixtures thereof. The silicon particle may be of any form including fibers, whiskers, sheets, etc. and in very small sizes.

The matrix is then processed via typical processing. As an example, polymer infiltration and pyrolysis, slurry or tape casting, etc. may be performed to further process the matrix. This processing occurs at a temperature below the melting point of the silicon template material <NUM>.

After a prescribed state has been reached, as an example, an appropriate porosity level for substrate <NUM>, the matrix is put through a melt infiltration step at a temperature of above the melting point of the template material <NUM>. Thus, the template will melt and wick or infiltrate or otherwise relocate into the porosity of the substrate and leave a void space such as shown at <NUM> in <FIG>. Thus, the voids <NUM> become the cooling channels, in this example, while the matrix <NUM> provides the body of the component <NUM>. Appropriate choice of substrate and template morphologies enables control of the geometries of voids <NUM>. As an example, fibrous substrates and particulate templates can produce voids <NUM> with an elongated morphology.

This method is applicable to components formed by other materials, including other composites or monolithic structures or organic matrix composites. Notably, particular attention may be required with regard to the template materials for these alternative matrix materials.

This method, thus, forms cooling channels, hollow cavities, or other deliberately formed voids, which can be costly and difficult to produce by other methods within CMC materials. Challenges to incorporating these features from the beginning of CMC processing include design complexity due to the ceramic fiber architecture and compatibility issues with subsequent CMC matrix processing methods. As an example, many processes would fill in the desired voids or hollows.

Challenges with forming hollow features subsequent to CMC processing primarily include high cost and technical limitations of machining and may result in damage to the CMC matrix or fiber. As an example, loss of strength or environmental durability due to fabric or matrix damage can occur. Also, additional processing treatments can raise challenges with regard to maintaining the voids in the matrix.

This in situ process to form the voids overcomes traditional design barriers. In particular, the cost of this method is relatively low and the likelihood of damage is also reduced from the prior art.

Other benefits with regard to CMC include facile incorporation of the invention with typical CMC materials.

Also, there may be remnant melt infiltration materials that are targeted. In the example component <NUM> shown in <FIG>, the substrate <NUM> is a carbon-rich polymer derived ceramic. The template is again silicon <NUM>.

As shown in <FIG>, after the melt process, the matrix <NUM> remains with the silicon template now having infiltrated the porosity of the matrix <NUM>, leaving voids <NUM>. As shown, there may be a layer <NUM> of silicon around the void or opening <NUM>. This can have additional environmental benefits as it isolates, or insulates, at least in part, the cooling air passing through the passage <NUM> from contacting the CMC material.

<FIG> shows another embodiment <NUM> wherein there is a silicon template <NUM> and a substrate <NUM>. After undergoing melting (see <FIG>), voids <NUM> remain within the matrix <NUM>. The substrate <NUM> may again be a carbon-rich polymer derived ceramic material, however, in another example, relatively small molybdenum, or other metallic particles <NUM> may also be utilized. This can result in molybdenum disilicide, or other metal silicide, regions <NUM> in the final matrix <NUM> as shown in <FIG>, preferentially reducing or eliminating the original silicon template material. The silicon template material can be partially or wholly eliminated in the final form. The MoSi<NUM>, or metal silicide, which is formed has a much higher melting point material than the original Si. While molybdenum is disclosed, metallic particles of other metals, including titanium, vanadium, chromium, cobalt, nickel, zirconium, niobium, hafnium, tantalum, tungsten, platinum, yttrium and boron may be utilized. All of these materials would result in a metal silicide region as mentioned above with regard to the molybdenum embodiment.

<FIG> schematically shows a subsequent method step wherein a tool <NUM> is depositing infiltration material <NUM> into or onto a component <NUM> having voids <NUM> formed by the method of this disclosure. Thus, this method may be utilized to form such voids as an intermediate step such that the voids <NUM> better facilitate the depositing or infiltration of material <NUM> throughout the component <NUM>. The voids may then be utilized for subsequent deposition or infiltration processes, to allow material to pass through the voids, and then into the matrix. In some of these methods, the voids can remain hollow after the subsequent process. Additionally, this method can be utilized not only to have voids in a final component, but may be utilized to form such voids as an intermediate step, the voids <NUM> then being filled by different materials for various known reasons.

In this invention, a diameter of the void is extremely small. Average hydraulic diameters are greater than or equal to about ten and less than or equal to about <NUM> microns in scale.

The teachings are broadly applicable to hybrid CMC processing methods including polymer infiltration and pyrolysis, chemical vapor infiltration, melt infiltration, and glass transfer molding as examples.

Claim 1:
A method of creating a component (<NUM>, <NUM>) comprising:
forming a ceramic matrix composite (CMC) substrate (<NUM>) and depositing a template material (<NUM>) within said substrate (<NUM>), such that there are a plurality of template members;
processing the substrate (<NUM>) to provide an appropriate porosity level; and
heating said substrate (<NUM>) to a temperature above a melting point of said template material (<NUM>), such that said template material (<NUM>) wicks into the porosity of said substrate (<NUM>) and forms a component (<NUM>, <NUM>) formed of a matrix material (<NUM>) having voids (<NUM>), wherein an average hydraulic diameter of said voids (<NUM>, <NUM>) is greater than or equal to about <NUM> and less than or equal to about <NUM> microns, wherein said template material (<NUM>) is silicon and said component (<NUM>, <NUM>) is for use in a gas turbine engine.