Process for producing a self-healing layer on a part made of a C/C composite

1. A composite material part having a protective coating against oxidation, the protective coating comprising:

a first self-healing phase formed in a majority by a borosilicate system,

a second self-healing phase based on silicate, and

a filler formed by silicon carbide grains,

wherein said second self-healing phase includes at least one ultra-refractory oxide, the at least one ultra-refractory oxide being Y 2 O 3 ,

wherein, in a softened state, the second self-healing phase based on silicate and including the at least one ultra-refractory oxide spreads in a form of drops and surrounds the silicon carbide grains, each drop surrounding a silicon carbide grain, so as to mitigate a loss of ability to wet carbon and maintain a protective film of the second self-healing phase in contact with a surface of the part.

2. A part according to claim 1 , wherein the coating further includes silicon.

3. A part according to claim 1 , wherein the coating further includes a borosilicate mixture.

4. A part according to claim 1 , wherein the coating further includes at least one glass-modifier oxide.

5. A part according to claim 1 , wherein the silicon carbide grains present mean size lying in the range 5 μm to 50 μm.

6. A part according to claim 1 , further comprising a mechanical protection surface layer on the protective coating.

7. A part according to claim 1 , wherein said part is a friction part made of carbon/carbon composite material.

8. A part according to claim 7 , wherein said part is provided with the protective coating on its surfaces other than its friction surface(s).

9. A part according to claim 1 , wherein said part is a diverging portion of a rocket engine nozzle made of carbon/carbon composite material with at least an inside surface thereof being provided with the protective coating.