Thermostructural composite structure with a compositional gradient and its manufacturing process
View Patent ↗Thermostructural composite structure having a compositional gradient, formed from a porous core ( 5 ) made of a refractory having a pore volume content of greater than or equal to 80%. The core ( 5 ) lies between two intermediate layers ( 6 a, 6 b ) comprising the carbon fiber reinforcement, densified by a matrix composed of the carbon phase and of a ceramic phase, and a refractory solid filler. Two monolithic ceramic shells ( 7 a, 7 b ) cover the intermediate layers in order to give stiffness to the entire structure.
1. A thermostructural composite structure having a density gradient, formed from a porous core made of a refractory having a pore volume content of greater than or equal to 80%, said core lying between two intermediate layers comprising part of the refractory of the porous core and a ceramic phase and a refractory solid filler, and two external shells made of a ceramic covering said intermediate layers.
2. The structure as claimed in claim 1 , wherein the refractory of the porous core consists of a refractory fiber reinforcement consolidated by a matrix.
3. The structure as claimed in claim 2 , wherein the reinforcement comprises carbon fibers of the ex-rayon type bonded together by a carbon matrix.
4. The structure as claimed in claim 3 , wherein:
the intermediate layers are anchored on the porous core while the ceramic shells are anchored on the intermediate layers;
said structure has a bulk density of less than 1;
said structure includes a number of cavities having walls that form stiffeners;
the stiffeners have a wall thickness ranging up to 1 mm;
the stiffeners have hollowed-out portions;
the ceramic shells are composed of silicon carbide.
5. The structure as claimed in claim 1 , wherein the intermediate layers are anchored on the porous core while the ceramic shells are anchored on the intermediate layers.
6. The structure as claimed in claim 1 , which has a bulk density of less than 1.
7. The structure as claimed m claim 1 , which includes a number of cavities having walls that form stiffeners.
8. The structure as claimed in claim 7 , wherein the stiffeners have a wall thickness ranging up to 1 mm.
9. The structure as claimed in claim 8 , which includes at least one optical surface integrally formed with the stiffeners.
10. The structure as claimed in claim 7 , wherein the stiffeners have hollowed-out portions.
11. The structure as claimed in claim 7 , which includes at least one optical surface.
12. The structure as claimed in claim 1 , wherein the ceramic is composed of silicon carbide.