摘要:
The invention relates to a method of making a refractory carbide layer on the accessible surface of a C/C composite material, the method including a step consisting in placing the composite material in contact with a reactive composition in solid form that contains an atomic proportion greater than or equal to one-third and less than or equal to 95% of a metal that is a precursor of a determined carbide having a melting temperature greater than 2000° C., and an atomic proportion of silicon that is greater than or equal to 5% and less than or equal to two-thirds. The method further includes a step consisting in impregnating the accessible surface of the C/C composite material with the reactive composition melted at a temperature that is greater than or equal to the melting temperature of the metal that is a precursor of a determined carbide.
摘要:
One or more porous substrates for densification (10) are loaded into an oven (12) into which there is admitted a reaction gas containing a pyrolytic carbon precursor gas comprising at least one gaseous hydrocarbons CxHy in which x and y are integers and x is such that 1
摘要:
A part made of a composite material containing carbon, having an open internal residual porosity is protected against oxidation by performing at least one stage in which an impregnating composition is applied, said impregnating composition containing at least one metal phosphate and titanium diboride. Efficient protection against oxidation is thus obtained at temperatures of more than 1000° C., also in the presence of a carbon oxidation catalyst and in a damp medium.
摘要:
An oxidation-sensitive composite has applied thereto a composition comprising a mixture of boride powder constituted for the most part of TiB2, at least one vitreous refractory oxide powder constituted for the most part by a mixture of borosilicate glass, and a binder containing a ceramic-precursor resin. The resin is cured and is subsequently transformed into a ceramic by heat treatment or during first exposure of the coated part to high temperatures.
摘要:
Between the start and the end of the chemical vapor infiltration process, filtration conditions are modified by causing at least one of the following infiltration parameters to vary: retention time of the gas, pressure, temperature, concentration of precursor in the gas, and concentration of dopant, if any, in the gas; thereby adapting infiltration conditions to changes in the porometry of the substrate in order to control the microstructure of the material deposited within the substrate, in particular in order to conserve a microstructure that is constant.
摘要:
An interposition layer (12) is formed on the outside surface of a part (10) made of thermostructural composite material containing carbon, and a metal case is formed by casting molten metal (22) around the part provided with its interposition layer. The interposition layer has closed porosity and it is proof against the metal of the case, such that shrinkage of the metal during cooling is absorbed by compacting or collapsing the porosity of the interposition layer, thereby preserving the integrity of the metal case, and the interposition layer constitutes a diffusion barrier preventing eutetics forming by contact between the metal of the case and the composite material.
摘要:
A ceramic material based on Sialon, in particular on .beta.'-Sialon is obtained by reducing an aluminosilicate precursor by means of a gas phase comprising a mixture of hydrogen and nitrogen doped with a gaseous carbon compound. The gaseous carbon compound is a gas containing carbon in combined form, e.g. an alkane, and its concentration by volume in the gas is less than 3%. The method is particularly suitable for forming Sialon-based coatings on substrates that are solid or fibrous. For composite materials constituted by a fiber preform densified by means of a matrix, the method can be used to form an interphase coating on the fibers of the preform prior to densifying the preform, or the method can be used to form a matrix that is based on Sialon.
摘要:
A method and apparatus for a continuous coating of a part may include providing a separation layer made of a material that is weaker than the material of the coating to be made. The part may be placed on one or more supports, the supports coated with the separation layer. A continuity layer of a component material of the coating to be made is interposed between the part and the or each support, at least in vicinity of the or each support zone. The coating is formed by chemical vapor infiltration or deposition, and the part is then separated from the or each support by rupture within the separation layer, the continuity of the coating of the part in the or each support zone being provided by the portion of the coating that comes from the continuity layer that remains in place on the part.
摘要:
A thin, refractory, intermediate adhesive layer of laminar structure is deposited in oriented fashion on the reinforcing fibers by chemical vapor deposition, this intermediate layer having a greater elongation at break than the matrix and having a thickness of between 0.2 and 3 micrometers; the material forming the intermediate layer can be laminar pyrocarbon or boron nitride; the ceramic matrix is then infiltered, preferably by chemical vapor deposition, inside the pores of the reinforcement.
摘要:
A refractory material that can withstand high temperatures in an oxidizing medium and containing at least: a first constituent corresponding to hafnium, or to a non-oxide compound of hafnium, or circular in a or a non-oxide compound of zirconium, or corresponding to a mixture of at least two metals and/or compounds selected from hafnium a non-oxide compound of hafnium, zirconium, and a non-oxide compound of zirconium; a second constituent corresponding to the boron or to a non-oxide compound of boron, or corresponding to a mixture of boron and a non-oxide compound of boron; and a third constituent corresponding to a rare earth RE or to a non-oxide compound of the rare earth RE, or corresponding to a mixture of rare earth RE and a non-oxide compound of the rare earth RE, where RE is selected from scandium, yttrium, and the lanthanides. The material contains neither silicon nor a compound of silicon.