1. A method for modifying a carbonized substrate, comprising:
providing a carbonized substrate;
providing a mixture containing a hydrophobic polymer and a carbonaceous material;
applying the mixture onto at least one surface of the carbonized substrate; and
thermally treating the carbonized substrate under the protection of an inert gas.
2. The method according to claim 1, wherein the carbonized substrate is selected from a group consisting of carbon cloth, carbon paper, and carbon felt.
3. The method according to claim 1, wherein the hydrophobic polymer is selected from a group consisting of polytetrafluoroethylene (PTEF), polyhexafluoropropylene (PHFP), copolymers of hexafluoropropylene and tetrafluoroethylene (FEP), copolymers of tetrafluoroethylene and perfluoropropylvinylether (PFA), copolymers of tetrafluoroethylene and perfluoromethylvinylether (MFA), homopolymers of chlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), poly(vinylfluoride) (PVF), copolymer of tetrafluoroethylene and ethylene (ETFT), copolymer of vinylidene fluoride and hexafluoropropylene and tetrafluoroethylene (THV), and combinations thereof.
4. The method according to claim 1, wherein the carbonaceous material comprises a powdered carbonaceous material, a fibrous carbonaceous material, or a combination thereof.
5. The method according to claim 1, wherein the carbonaceous material is selected from a group consisting of carbon black, graphite, acetylene black, and combinations thereof.
6. The method according to claim 1, wherein the applying step is performed by a manner selected from a group consisting of spraying, screen printing, coating, immersing, and combinations thereof.
7. The method according to claim 1, wherein the mixture is applied onto the both surfaces of the carbonized substrate.
8. The method according to claim 1, further comprising a drying step before the thermal treatment step.
9. The method according to claim 8, wherein the drying step is performed at a temperature ranging from about 70\xb0 C. to about 150\xb0 C.
10. The method according to claim 8, wherein the applying step and the drying step are recycled for 1 to 10 times.
11. The method according to claim 1, wherein the inert gas is selected from a group consisting of nitrogen, helium, argon, and combinations thereof.
12. The method according to claim 1, wherein the temperature of the thermal treatment is higher than the melting point of the hydrophobic polymer.
13. The method according to claim 12, wherein the thermal treatment is performed at a temperature ranging from about 200\xb0 C. to about 450\xb0 C. for about 5 minutes to about 120 hours.
14. A modified carbonized substrate, comprising:
a carbonized substrate; and
a leveling layer substantially directly disposed on at least one surface of the carbonized substrate.
15. The modified carbonized substrate according to claim 14, wherein the carbonized substrate is selected from a group consisting of carbon cloth, carbon paper, and carbon felt.
16. The modified carbonized substrate according to claim 14, wherein the leveling layer comprises a hydrophobic polymer and a carbonaceous material.
17. The modified carbonized substrate according claim 16, wherein the hydrophobic polymer is selected from a group consisting of PTFE, PHFP, FEP, PFA, MFA, PCTFE, PVDF, PVF, ETFT, THV, and combinations thereof.
18. The modified carbonized substrate according to claim 16, wherein the carbonaceous material comprises a powdered carbonaceous material, a fibrous carbonaceous material, or a combination thereof.
19. The modified carbonized substrate according to claim 16, wherein the carbonaceous material is selected from a group consisting of carbon black, graphite, acetylene black, and combinations thereof.
20. The modified carbonized substrate according to claim 14, for use in a gas diffusion layer of an electrode in a fuel cell.
21. A fuel cell comprising an anode and a cathode, wherein at least either the anode or the cathode comprises the modified carbonized substrate according to claim 14.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A double-cone device of continuous geometry for creating a pressure difference in a fluid flowing through the device, the device comprising:
a. a first tapering section of essentially hollow frustroconical shape; and
b. a second diverging section of essentially hollow frustroconical shape,
wherein the section of minimum diameter of the device is an orifice of the device,
wherein the second diverging section has a plurality of holes on its surface beyond the orifice in order to achieve suction.
2. The device according to claim 1, wherein conical angle of the first tapering section is greater than 0\xb0 and at most 10\xb0, preferably at most 5\xb0.
3. The device according to claim 1, wherein conical angle of the second diverging section is greater than 0\xb0 and at most 10\xb0, preferably at most 4\xb0.
4. The device according to claim 1, wherein the holes are of circular shape.
5. The device according to claim 1, wherein the holes are inclined in the direction of the flow of the fluid.
6. The device according to claim 1, wherein the holes have diameter that is less than half the diameter of the orifice section.
7. The device according to claim 1, wherein the holes are made at the orifice.
8. The device according to claim 1, wherein the holes are made on a portion of the second diverging section with diameter greater than the diameter of the orifice and less than 1.5 times the diameter of the orifice.
9. A double-cone device of continuous geometry for creating a pressure difference in a fluid flowing through the device, the device comprising:
a. a first tapering section of essentially hollow frustroconical shape;
b. a second porous diverging section of essentially hollow frustroconical shape to achieve suction; and
c. a third diverging section of essentially hollow frustroconical shape, extending from the end of the porous section.
10. The device according to claim 9, wherein conical angle of the first tapering section is greater than 0\xb0 and at most 10\xb0, preferably at most 5\xb0.
11. The device according to claim 9, wherein conical angle of the third diverging section is greater than 0\xb0 and at most 10\xb0, preferably at most 4\xb0.
12. The device according to claim 9, wherein the porous section has larger diameter greater than smaller diameter of the first tapering section and less than 1.5 times the smaller diameter of the first tapering section.
13. A double-cone device for creating a pressure difference in a fluid flowing through the device, the device comprising:
a. a first tapering section of essentially hollow frustroconical shape;
b. a second diverging section of essentially hollow frustroconical shape; and
c. an insert section having a central hollow frustroconical portion, the hollow portion having the smaller diameter end matched to the smaller diameter end of the first tapering section and the larger diameter end matched to the smaller diameter end of the second diverging section, the insert extending from the smaller diameter end of first tapering section to the beginning of the second diverging section, wherein the insert section has a plurality of radial holes on the central hollow portion to facilitate suction.
14. The device according to claim 13, wherein conical angle of the first tapering section is greater than 0\xb0 and at most 10\xb0.
15. The device according to claim 13, wherein conical angle of the second diverging section is greater than 0\xb0 and at most 10\xb0, preferably at most 2\xb0.