US-12618150-B2 - Device for chemical vapour deposition

US12618150B2US 12618150 B2US12618150 B2US 12618150B2US-12618150-B2

Abstract

A device for fluidised bed chemical vapour deposition, includes a reactor including a treatment zone in which the fluidised bed chemical vapour deposition is intended to be carried out using at least a first and a second reactive gas and a diffuser under the treatment zone delimiting the reactor, and a heating system configured to heat at least the treatment zone. The device includes a first channel for introducing the first reactive gas and a second channel for introducing the second reactive gas, which second channel is separate from the first channel and opens out under the diffuser, and wherein the first introduction channel is capable of being moved with respect to the heating system.

Inventors

Arnaud DELEHOUZE
Rémi Pierre Robert Bouvier
Manon FERNANDEZ

Assignees

SAFRAN CERAMICS

Dates

Publication Date: 20260505
Application Date: 20220810
Priority Date: 20210820

Claims (4)

1 . A method for coating particles by fluidised bed chemical vapour deposition, comprising: introducing particles into the treatment zone of a reactor, the particles being made of ceramic material or of carbon; introducing a first reactive gas into a first channel for introducing gas; introducing a second reactive gas into a second channel for introducing gas, which second channel is separate from the first channel for introducing gas; and heating, with a heating system, the treatment zone to a temperature enabling the reaction of the first and second reactive gases in the treatment zone so as to coat the particles, the first introduction channel opening out into a zone where the temperature is greater than that of the zone where the second channel opens out, wherein the first introduction channel is movable with respect to the heating system, and/or wherein the method further comprises moving the first introduction channel with respect to the heating system before introducing the first reactive gas and/or varying a position of the first introduction channel with respect to the heating system during the course of the coating method.
2 . The coating method according to claim 1 , wherein the particles are short fibres having an average length less than or equal to 5 mm.
3 . The coating method according to claim 1 , wherein the first and second reactive gases are BCl 3 and NH 3 , so as to coat the particles with boron nitride.
4 . The coating method according to claim 1 , further comprising an additional heating step, carried out in a zone downstream of the treatment zone where the temperature is higher than in the treatment zone.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the U.S. National Stage of PCT/FR2022/051574, filed Aug. 10, 2022, which in turn claims priority to French patent application number 21 08807 filed Aug. 20, 2021. The content of these applications are incorporated herein by reference in their entireties. TECHNICAL FIELD The present invention relates to the field of ceramic matrix composite materials, and more particularly to the field of coatings for reinforcement particles made of such materials and the methods for obtaining same. PRIOR ART Ceramic matrix composite materials (CMC materials) have good thermostructural properties, in other words high mechanical properties which make them suitable for forming structural parts, and the ability to retain these properties at high-temperatures. CMC parts may comprise a textile reinforcement formed of long continuous fibres woven in the stress directions of the final composite part. The weaving step is an expensive step and the use of a woven fibrous reinforcement may present limitations in the case of parts with complex geometry or small size. Indeed, the minimum weaving pitch may prove too coarse for producing a small geometric detail. In order to solve this problem, it has been envisaged to use a reinforcement that is no longer formed of long continuous fibres, but of particles of smaller dimensions dispersed in the matrix. However, it is well-known that the function of a CMC material requires specific management of the interfacial bonds between reinforcement and matrix, in order to obtain the hard to damage nature of the final composite. This modulation of the interfaces is conventionally obtained by positioning an interphase between the reinforcement and the matrix. Conventionally, reinforcements consisting of particles with small dimensions, and coated with an interphase are obtained by cutting long fibres that are themselves coated. It is however observed, on the one hand, that the cutting cross-sections are not coated and, on the other hand, that the cutting step damages the coating which may degrade its properties. It is therefore desirable to have a device that can directly coat particles intended to form the reinforcement of the ceramic matrix composite material. DISCLOSURE OF THE INVENTION For this purpose, the inventors are proposing a device for fluidised bed chemical vapour deposition, comprising: a reactor comprising a treatment zone in which the fluidised bed chemical vapour deposition is intended to be carried out using at least a first and a second reactive gas and a diffuser under the treatment zone delimiting the reactor,and a heating system configured to heat at least the treatment zone,the device being characterised in that it comprises a first channel for introducing the first reactive gas and a second channel for introducing the second reactive gas, which second channel is separate from the first channel and opens out under the diffuser, and in that the first introduction channel is capable of being moved with respect to the heating system. The inventors have observed that a device such as described above can best control the conditions under which the mixture of two reactive gases takes place. In particular, the mobility of the first introduction channel with respect to the heating system can ensure that the mixture of first and second reactive gases takes place at an optimum gas-mixture temperature. The optimum gas mixture temperature is understood as the temperature at which it is advantageous to carry out the mixing of said reactive gases. For example, this may avoid any loss of reagent due to the formation of undesired products, or improve the mixing conditions of the reactive gases. It should be noted that reaction of the reactive gases with one another once mixed at the optimum mixing temperature is not excluded, provided that such reactions are beneficial for the subsequent formation of the desired deposit. In certain cases, the optimum mixing temperature can correspond to the reaction temperature at which the fluidised bed chemical vapour deposition is intended to be carried out. Thus, the reactive gases can be mixed directly at the reaction temperature in the treatment zone, in order to react directly when they are mixed to form the desired deposit. This optimum temperature is individual to each pair of first and second reactive gases chosen, and depends, in particular, on the physico-chemical properties of the reactive gases. For example, in the particular case where a coating of boron nitride (BN) is desired, for example in the case where the first reactive gas is BCl3 and the second reactive gas is NH3 (or vice-versa), the optimum mixing temperature of the gases is the temperature range between 400° C. and 700° C. and preferably the temperature range between 400° C. and 600° C. For example, when a BN coating is desired, the relative position of the first introduction channel introduction with respect to the heating sy