CMC articles having small complex features
A ceramic matrix composite (CMC) component for gas turbine engines, the component having fine features such as thin edges with thicknesses of less than about 0.030 inches and small radii of less that about 0.030 inches formed using the combination of prepreg plies layed up with non-ply ceramic inserts. The CMC components of the present invention replace small ply inserts cut to size to fit into areas of contour change or thickness change, and replace the small ply inserts with a fabricated single piece discontinuously reinforced composite insert, resulting in fewer defects, such as wrinkles, and better dimensional control.
1. A hot section gas turbine engine component, comprising:
a cured, reinforced, ceramic matrix composite portion comprising a plurality of continuous tows extending substantially parallel to each other in a matrix;
a discontinuously reinforced composite portion having substantially isotropic properties located at regions of contour changes and thickness changes of the component, the discontinuously reinforced composite portion comprising discontinuous fiber-including material selected from the group consisting of fiber, tow, and chopped pre-preg plies in a matrix material;
wherein the discontinuously-reinforced composite portion is adjacent to the reinforced ceramic matrix composite portion comprising the plurality of continuous tows, and
the discontinuously reinforced composite portion is cured to the reinforced ceramic matrix composite portion.
2. The hot section gas turbine component of claim 1 , wherein the cured, reinforced ceramic matrix composite portion further includes a plurality of groups of continuous tows in a matrix, the tows in each group extending substantially parallel to each other in a matrix and each group oriented at a preselected angle to the tows in at least one other group.
3. The hot section gas turbine component of claim 1 wherein a first group of tows is oriented at a first preselected angle selected from the group consisting of 0°, +45°, −45°, 90°, −45°, +45°, wherein the tows oriented at 0° are oriented parallel to an axis of the component, and the tows in the at least one other group adjacent to the first group are oriented at a second preselected angle different than the preselected angle of the adjacent group, the second preselected angle selected from the group consisting of 0°, +45°, −45°, 90°, −45°, +45°.
4. The hot section gas component of claim 1 wherein the discontinuously-reinforced composite portion having substantially isotropic properties located at regions of contour changes and thickness changes is located along a corner of a turbine component.
5. The hot section gas component of claim 1 wherein the discontinuously-reinforced composite portion having substantially isotropic properties located at regions of contour changes and thickness changes is positioned as a stiffener at a thickness change.
6. The hot section gas component of claim 1 wherein the fiber-including material has a size of from about 0.1 inch to about 1 inch.
7. The hot section component of claim 1 wherein the discontinuously-reinforced composite portion comprising discontinuous fiber-including material in a matrix material further includes a loading of about 10% by volume to about 50% by volume of fiber-including material in matrix material.
8. The hot section component of claim 1 wherein the turbine component is a narrow chord turbine blade and the discontinuously-reinforced composite portion having substantially isotropic properties is located in a trailing edge portion of the blade, a cured, reinforced, ceramic matrix composite portion bonded to the discontinuously reinforced composite portion.
9. The hot section component of claim 1 wherein the turbine component is a narrow chord turbine blade and the discontinuously-reinforced composite portion having substantially isotropic properties and wherein the portion is positioned at a change in contour adjacent an air passageway as a rib.