Procedure for preparing a multilayer coating of carbide ceramics on, and possibly in, a piece of a carbon material, by a technique of reactive infiltration in the RMI molten state

摘要

Process for preparing a multilayer coating of metal carbides on at least one surface of a first carbon layer of a substrate, and possibly under said surface inside said first carbon layer, by a molten reactive infiltration technique , in which the following steps a) to d) are carried out: a) the surface is contacted with a solid MSi2 metal disilicide in which M is chosen from hafnium, titanium and tantalum; b) the substrate and the metal disilicide are heated to a temperature TP higher than the melting temperature of the metal disilicide; c) a plateau is observed at the temperature TP for a period sufficient for the metal disilicide to react with the carbon and form a first multilayer coating comprising a dense and continuous layer constituted by SiC, completely covered by a dense and continuous layer constituted by MC; d) the part provided with the first multilayer coating is cooled; then, at the end of step d), the following step e) is also eventually carried out: e) a second layer of carbon is deposited on the surface of the first multilayer coating; at the end of stage d) or stage e), the following successive stages f) ai) are also carried out: f) the surface of the first multilayer carbon-containing coating is also contacted, or the surface of the second layer carbon, with a solid MSi2 metal disilicide in which M is chosen from hafnium, titanium and tantalum; g) the surface of the first multilayer coating which also contains carbon and metal disiliciide, or the second layer of carbon and metal disiliciide, is heated to a temperature TP higher than the melting temperature of the metal disiliciide; h) a plateau is observed at the temperature TP for a period sufficient for the metal disilicide to react with the carbon and form a second multilayer coating comprising a dense and continuous layer constituted by SiC, completely covered by a dense and continuous layer constituted by MC; i) the part provided with the second multilayer coating is cooled; then, at the end of step i), the following step j) is also carried out: j) a third layer of carbon is deposited on the surface of the second multilayer coating; and at the end of stage i) or stage j), the following stage k) is also carried out: k) a siliciuration of the surface of the second multilayer coating also containing carbon, or of the third layer of carbon is carried out , by liquid Si, whereby a layer of SiC is obtained on the second multilayer coating.