METHOD FOR MANUFACTURING A TANK FOR THE CONTAINMENT OF A PRESSURIZED GAS, IN PARTICULAR HYDROGEN

1 . A method for a manufacture of a composite tank having a continuous fiber reinforcement, a prismatic shape, and a thickness e, for storage of a pressurized gas in an internal cavity of said composite tank, said composite tank comprising fibers extending between two non-contiguous faces of said composite tank through the internal cavity, wherein the method comprises the steps of:

i. obtaining a prismatic fibrous preform with a thickness e comprising continuous three-dimensional reinforcements throughout the thickness;

ii. impregnating an outer layer of said prismatic fibrous preform with a polymer over a thickness of less than ¼ of the thickness e so as to constitute a composite outer shell extending over all faces of the prismatic shape; and

iii. forming a sealed layer constituting an inner lining, a thickness less than 1/10 th of the thickness e between the composite outer shell and a fibrous network in the internal cavity of the composite tank.

2 . The method according to claim 1 , wherein step iii) comprises, before step i), a step of:

iii.a obtaining a shell constituting the inner lining by a plastic injection method and wherein step i) comprises steps of:

i.a draping fibrous plies on an outer surface of the shell constituting the inner lining; and

i.b inserting fibers by stitching between two non-contiguous faces of the prismatic fibrous preform through the fibrous plies deposited in step i.a) and the inner lining obtained in step iii.a).

3 . The method according to claim 2 , wherein the inner lining obtained in step iii.a) comprises hollow spacers extending between two of non-contiguous faces and wherein the fibers inserted by stitching in step i.b) pass inside the hollow spacers.

4 . The method according to claim 1 , wherein step ii) comprises, after step i), steps of:

ii.a packing the prismatic fibrous preform obtained in step i) into a sealed enclosure;

ii.b. creating a vacuum within the sealed enclosure comprising the prismatic fibrous preform;

ii.c filling the sealed enclosure comprising the prismatic fibrous preform with a liquid;

ii.d freezing the prismatic fibrous preform soaked with the liquid;

ii.e freeze-drying an outer layer of the prismatic fibrous preform;

ii.f impregnating said outer layer of a polymer so as to constitute the composite outer shell; and

ii.g discharging any remaining liquid from the prismatic fibrous preform.

5 . The method according to claim 4 , wherein the liquid introduced in step ii.c) is water.

6 . The method according to claim 4 , wherein the liquid introduced in step ii.c) is a sol-gel.

7 . The method according to claim 1 , comprising a step, before or after the step ii) of impregnating the composite outer shell, including integrating into the prismatic fibrous preform a coupling passing through said composite outer shell and able to put into fluid communication an inside of the prismatic fibrous preform and an outside of the prismatic fibrous preform.

8 . The method according to claim 4 wherein the liquid is water and wherein a coupling is used in step ii.g) to suck the water out from the prismatic fibrous preform and the method comprises during step iii), once the water is discharged, a step of:

iii.b solidifying the fibrous network inside the internal cavity.

9 . The method according to claim 8 , wherein step iii.b) comprises spraying a polymer through the coupling inside the prismatic fibrous preform so as to constitute the inner lining and solidifying the fibrous network within said internal cavity.

10 . The method according to claim 8 , wherein step iii.b) comprises an injection of a sol-gel into the internal cavity and solidification of the fibrous network within said internal cavity by evaporation of a liquid phase of the sol-gel.

11 . The method according to claim 4 , wherein the liquid is a sol-gel and wherein a coupling is used during step ii.g) to evaporate a liquid phase of the sol-gel inside the prismatic fibrous preform, and wherein step iii) is carried out by polymerization of the sol-gel.

12 . The method according to claim 7 , comprising after step iii) a step of:

iv. creating holding strips surrounding the composite tank by filament winding.