Method for delivering a molten silicon composition into porous substrates

A method of incorporating a metal-based composition simultaneously in a plurality of porous substrates, comprising the steps of:

• providing a plurality of sources of metal-based composition, each source comprising a majority phase formed by the metal-based composition and a minority phase suitable for forming a retention and drainage structure for the metal-based composition when in the molten state, and each source being in the form of a layer having opposite first and second surfaces,
• forming at least one vertical multilayer stack of alternating porous substrates and sources of metal-based composition, the or each source located between two consecutive substrates having its first surface in contact with an upper surface of one of said two consecutive substrates and its second surface in contact with a lower surface of the other one of said two consecutive substrates, with rigid spacers being provided over the whole height of each interval between two consecutive substrates where a source is located, and
• heating the stack at a temperature higher than the melting temperature of the metal-based composition to cause the metal-based composition in the molten state from each source to migrate through the adjacent surface of the or each substrate adjacent to said source, towards the inside of the substrate, the metal-based composition of each source located between two consecutive porous substrates migrating towards the inside of said two consecutive substrates respectively downwardly and upwardly, said spacers preventing the sources to be crushed during the process of incorporation of the metal-based composition into the porous substrates.