Method for manufacturing filtering membranes by additive technique and resulting membranes

A process for the manufacture of a tangential filtration membrane comprising:

• a support exhibiting a three-dimensional structure and being composed of a monolithic ceramic porous body, with circulation pathways for the fluid to be filtered, said porous body exhibiting an open porous texture that forms a network of interconnected pores, said support exhibiting a mean pore diameter belonging to a range extending from 4 μm to 40 μm, and
• at least one separating filtration layer deposited over a wall of each of the circulation pathways,
• the process comprising:
• producing the three-dimensional structure of the support by an additive technique in which the three-dimensional structure of the support is cut into slices using a computer design software, wherein the slices are produced one by one in the form of superimposed individual sheets successively bonded to one another, by repetition of the following two stages:
• a) deposition of an homogeneous continuous bed of powdered substance of unvarying thickness intended to form the ceramic porous body along a surface greater than the pattern selected by CAD of the section of the porous body to form taken at the level of the sheet;
• and
• b) localized consolidation of a portion of the deposited powdered substance according to a predetermined pattern for each sheet, in order to create the individual sheet,
• wherein stages a) and b) are repeated so as to allow, at each repetition, a simultaneous bonding of the individual sheet thus formed to the preceding sheet, if present, so as to bring about the progressive growth of the desired three-dimensional shape comprising circulation pathways, with an open porous texture that forms a network of interconnected pores, and having a mean pore diameter in a range of from 4 μm to 40 μm,
• creating the separating filtration layer having a smaller mean pore diameter than the support:
• either by deposition after formation of the porous body in order to create the surface intended to be in contact with the fluid to be treated, such that the support and the separating filtration layer formed thereby are made of the same or different material,
• or created by the variation of the energy contribution so as to obtain a porosity gradient within one and the same sheet, such that the support and the separating filtration layer formed thereby are made of the same material.