Patent Application
20240173890
A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-pressure and temperature exhaust gas flow. The high-pressure and temperature exhaust gas flow expands through the turbine section to drive the compressor and the fan section. The compressor section may include low and high pressure compressors, and the turbine section may also include low and high pressure turbines.
Airfoils in the turbine section are typically formed of a superalloy and may include thermal barrier coatings to extend temperature capability and lifetime. Ceramic matrix composite (“CMC”) materials are also being considered for airfoils. Among other attractive properties, CMCs have high temperature resistance. Despite this attribute, however, there are unique challenges to implementing CMCs in airfoils.
A fixture for processing a ceramic matrix composite article according to an example of the present disclosure includes first and second tool segments that each have an exterior side and an interior side. The first and second tool segments define there between a working region for holding a fiber preform that is to be densified with a ceramic material. Each of the interior sides has grooves for delivering a precursor gas to the working region.
In a further embodiment of any of the foregoing embodiments, the first and second tool segments include graphite.
In a further embodiment of any of the foregoing embodiments, the grooves are elongated along the interior side.
In a further embodiment of any of the foregoing embodiments, the interior side has a projected surface area in the working region, and the grooves are 33% to 66% of the projected surface area.
In a further embodiment of any of the foregoing embodiments, the first and second tool segments have having an array of through-holes connecting the exterior side and the interior side.
In a further embodiment of any of the foregoing embodiments, at least a portion of the through-holes intersect the grooves.
In a further embodiment of any of the foregoing embodiments, at least a portion of the through-holes are non-intersecting with the grooves.
In a further embodiment of any of the foregoing embodiments, the grooves are intersecting.
In a further embodiment of any of the foregoing embodiments, the grooves are non-intersecting.
In a further embodiment of any of the foregoing embodiments, the grooves have at least one inlet and at least one outlet that open to the exterior side.
A system for processing a ceramic matrix composite article according to an example of the present disclosure includes at least one fixture that has first and second tool segments that each have an exterior side and an interior side. The first and second tool segments define there between a working region for holding a fiber preform that is to be densified with a ceramic material. Each of the interior sides has grooves that have at least one inlet and at least one outlet that open to the exterior side. There is a source for providing a precursor gas, and a plenum connected to the source and the at least one inlet for providing the precursor gas to the working region via the grooves.
In a further embodiment of any of the foregoing embodiments, the at least one fixture includes multiple fixtures.
In a further embodiment of any of the foregoing embodiments, the grooves are elongated along the interior side, the interior side has a projected surface area in the working region, and the grooves are 33% to 66% of the projected surface area.
In a further embodiment of any of the foregoing embodiments, the first and second tool segments each have an array of through-holes that connect the exterior side and the interior side.
In a further embodiment of any of the foregoing embodiments, at least a portion of the through-holes intersect the grooves.
In a further embodiment of any of the foregoing embodiments, at least a portion of the through-holes are non-intersecting with the grooves.
In a further embodiment of any of the foregoing embodiments, the grooves are intersecting.
In a further embodiment of any of the foregoing embodiments, the grooves are non-intersecting.
In a further embodiment of any of the foregoing embodiments, the grooves have at least one inlet and at least one outlet that open to the exterior side.
The present disclosure may include any one or more of the individual features disclosed above and/or below alone or in any combination thereof.
The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.
In this disclosure, like reference numerals designate like elements where appropriate and reference numerals with the addition of one-hundred or multiples thereof designate modified elements that are understood to incorporate the same features and benefits of the corresponding elements.
Ceramic matrix composite (CMC) articles, such as but not limited to turbine blades, turbine vanes, blade outer air seals, and combustor panels may be fabricated via chemical vapor infiltration of a precursor gas into a fiber preform to deposit ceramic material on the fibers of the preform. In instances where the fiber preform is not self-supporting, a fixture may be used to support the preform in the desired geometry during processing. The fixture hinders flow of precursor gas to some regions of the fiber preform while permitting more flow to other regions, thereby contributing to uneven build-up of the ceramic material and concomitant lower performance of the article. Additionally, multiple fiber preforms may be processed simultaneously in a chamber through which the precursor gas flows. The flow may vary by spatial location in the chamber, thereby further contributing to uneven build-ups between articles that receive more or less flow. In these regards, as will be described below, the disclosed fixture facilitates improved flow of precursor gas into a fiber preform.
Each of the tool segments 12/14 has an exterior side 16a and an interior side 16b. The interior sides 16b are contoured for the article geometry, such as with a cavity in the shape of an airfoil. The interior sides 16b face each other to define a working region 18 where the fiber preform P is held. The terms “interior” and “exterior” are relative to the working region 18 in that the exterior side 16a generally faces away from the working region 18 and the interior side 16b generally faces toward the working region 18.
The fiber preform P is comprised of ceramic fibers arranged in a fiber architecture. The ceramic fibers are formed of bundles of filaments and may include, but are not limited to, silicon carbide (SiC) fibers, carbon (C) fibers or silicon nitride (Si3N4) fibers. For instance, the preform P may include multiple fiber layers or plies that are laid-up to form the geometry of the end-use article, or a portion thereof. In some instances, the fiber layers or plies are laid-up around one or more mandrels, which may remain in the preform P through a portion of the processing and then be removed later on to leave one or more internal cavities in the end-use article. In general, however, the preform P is initially devoid of any ceramic coating or matrix material.
The interior sides 16b of the tool segments 12/14 have elongated grooves 20 there along. Each groove 20 includes groove sides 20a and a bottom 20b. In the example in
The grooves 20 serve as passages for delivering the precursor gas to the working region 18 to densify (at least partially) the fiber preform P. The precursor gas may be for deposition of an interface coating material (e.g., boron nitride or silicon carbide) on the fibers or for a matrix material (e.g., silicon carbide). Although deep, wide grooves 20 may be desirable for enhancing flow of the precursor gas, the number, size, and pitch of the grooves 20 is balanced against other factors, such as fixture strength and support of the fiber preform P. For example, relatively large grooves may weaken the fixture by thinning the fixture walls. The grooves 20 are thus made to be relatively small in order to maintain good fixture strength. For example, the grooves 20 have a maximum depth and a maximum width of 0.050 inches to 0.200 inches to achieve good strength.
Land surfaces 16c between the grooves 20 serve as support surfaces for the fiber preform P and thus facilitate maintaining the design profile of the fiber preform P. For example, if the area of the land surfaces 16c is relatively small, the fiber preform P may be insufficiently supported and may deform and “drape” into the grooves 20. The fixture 10 thus provides plenty of land surface 16c in order to support and maintain the shape of the preform. For example, the interior side 16b has a projected surface area in the working region 18, and the grooves 20 are 33% to 66% of the projected surface area to achieve good support (the land surfaces 16c make up the remainder of the area). The “projected surface area” as used herein refers to the 2D area taken in a direction normal to the plane of the land surfaces 16c.
The grooves 20 may also be provided in a configuration that further facilitates supporting the fiber preform P and distributing the precursor gas. For example,
The tool segments 12/14 may also have through holes 22 (see also
Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.
The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.
