Aerospatiale Societe Nationale Industrielle

Societe Nationale Industrielle Et Aerospatiale

Frederic Saugnac

Guy J Larnac

Yves Grenie

Andre Marchand

A reinforcing fiber of the non-oxide ceramic type or of carbon to be used in the manufacture of a composite material with a glass, glass-ceramic or ceramic matrix, which composite exhibits good oxidative stability, is treated using a process comprising the steps consisting of: if necessary, oxidizing the fiber superficially or depositing thereon a layer of the same composition but including oxygen; placing the fiber in a chemical vapor deposition vessel; carrying out a pre-treatment at a temperature of 850.degree. to 1250.degree. C., in the presence of hydrogen, at a pressure of 50 to 300 mbar; injecting a mixture of neutral carrier gas and ammonia; stopping the injection and adjusting the pressure to a value of 1 to 10 mbar; injecting AlCl.sub.3 in a neutral diluting gas; producing on the fiber a deposit of AlN by simultaneously injecting a mixture of AlCl.sub.3 and a neutral carrier gas, and a mixture of NH.sub.3 and a neutral carrier gas, until the desired thickness of AlN is obtained; after stopping injection, cooling with a stream of neutral gas; and recovering the fiber.

Process for improving the oxidative stability of a composite material

Carbonaceous material according to the invention is protected against oxidation by boron carbonitride, which is infiltrated (4) or deposited in layer form (8) and which contains in atomic %;

Carbonaceous material protected against oxidation by boron carbonitride

This composite material with a fibrous reinforcement has refractory fibres (2) embedded in a nonmetallic matrix (4) and an interphase material (6) interposed between the fibres and the matrix, the interphase material being boron carbonitride with a lamellar or amorphous structure containing in atomic %, 0 to 98% nitrogen, 1 to 99% carbon and 1 to 99% boron. The composition of the interphase material can be homogeneous or vary gradually from the fibre-material interface (8) to the material-matrix interface (10).

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Pessac, France

Frederic Saugnac