Process for manufacturing a composite part

A process for manufacturing a composite part comprising:

• introducing an adhesion promoter into pores of a fibrous preform formed by threads covered with a coating having —OH groups on its surface, the adhesion promoter comprising an electron-withdrawing group G1 that is reactive according to a reaction of substitution or of nucleophilic addition with the —OH groups, and a reactive group G2 selected from:
• a hydroxyl function, an epoxide, a halogen atom, an amine function, a carbonyl function, a carbon-carbon double bond or a carbon-carbon triple bond,
• grafting the adhesion promoter to the surface of the coating by a reaction of substitution or nucleophilic addition of the —OH groups on the group G1, this grafting being carried out by a first heating of the fibrous preform into which the adhesion promoter has been introduced,
• introducing a ceramic precursor resin into the pores of the fibrous preform, after the step of grafting the adhesion promoter,
• polymerizing the resin introduced and bonding the grafted adhesion promoter to the resin by chemical reaction between these two compounds at the level of the group G2, said polymerizing and said bonding being carried out by a second heating of the fibrous preform into which the resin has been introduced, and
• forming a ceramic matrix phase in the pores of the fibrous preform by pyrolysis of the polymerized resin.