METHOD OF FABRICATING GRAPHITE FILMS
In a method of fabricating graphite films, mesophase pitch, a polymer material and an organic solvent are used to produce a carbon precursor slurry, and the carbon precursor slurry is coated to produce the graphite films. Since the method of using natural graphite as a raw material in production requires a number of purification processes to manufacture an expanded graphite powder before the graphite films can be produced, and thus the fabricating cost is very high, and other high-priced materials such as polyimide (PI) or graphene also will increase the total cost.
1 . A method of fabricating graphite films, characterized in that a mesophase pitch, an organic solvent, and a polymer material are used to fabricate a carbon precursor material for fabricating the graphite films, and the method comprises the steps of:
Step ( 11 ): fabricating a polymer-containing solvent from the organic solvent and the polymer material;
Step ( 12 ): fabricating a carbon precursor slurry from the polymer-containing solvent and the mesophase pitch;
Step ( 13 ): determining whether the viscosity of the carbon precursor slurry falls within a predetermined range, and entering into the Step ( 14 ) if the viscosity falls within the predetermined range, or returning to the Step ( 12 ), if the viscosity does not fall within the determined range;
Step ( 14 ): coating the carbon precursor slurry onto a surface of a metal foil;
Step ( 15 ): conducting oxidation treatment;
Step ( 16 ): removing the metal foil by an etching treatment; and
Step ( 17 ): conducting carbonization treatment and graphitization treatment.
2 . The method of fabricating graphite films of claim 1 , wherein the organic solvent of the Step ( 11 ) is one selected from the group consisting of ethanol, acetone, toluene, methylpyrrolidone, quinoline, pyridine, and a mixture thereof.
3 . The method of fabricating graphite films of claim 1 , wherein the polymer material of the Step ( 11 ) is one selected from the group consisting of polymethyl methacrylate, epoxy resin, phenolic resin, polycarbonate, polyimide, polyethylene terephthalate and a mixture thereof.
4 . The method of fabricating graphite films of claim 1 , wherein the mesophase pitch of the Step ( 12 ) has a content greater than an anisotropic area of 50 wt % or more.
5 . The method of fabricating graphite films of claim 1 , wherein the Steps ( 11 ) and ( 12 ) further respectively includes a rotation and a rotation speed.
6 . The method of fabricating graphite films of claim 5 , wherein the rotation time is controlled within a range of 0.1˜24 hrs.
7 . The method of fabricating graphite films of claim 1 , wherein the rotation speed is controlled within a range of 5˜100 rpm.
8 . The method of fabricating graphite films of claim 1 , wherein the slurry viscosity of the Step ( 13 ) falls within a range of 50˜1,000 cps.
9 . The method of fabricating graphite films of claim 1 , wherein the Step ( 14 ) is carried out by scraping.
10 . The method of fabricating graphite films of claim 9 , wherein a scraping speed is controlled within a range of 1˜10 mm/sec.
11 . The method of fabricating graphite films of claim 1 , wherein the metal foil of the Step ( 14 ) is one selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, and aluminum foil.
12 . The method of fabricating graphite films of claim 1 , wherein the metal foil of the Step ( 14 ) has a thickness smaller than 100 microns.
13 . The method of fabricating graphite films of claim 1 , wherein the thin film formed on a surface of the metal foil has a thickness smaller than 400 microns.
14 . The method of fabricating graphite films of claim 1 , wherein the oxidation treatment of the Step ( 15 ) further includes a oxidation temperature control and a oxidation time control.
15 . The method of fabricating graphite films of claim 14 , wherein the oxidation temperature is controlled within a range of 200˜300° C.
16 . The method of fabricating graphite films of claim 14 , wherein the oxidation time is controlled within a range of 0.1˜5 hrs.
17 . The method of fabricating graphite films of claim 1 , wherein an etchant for the etching treatment in the Step ( 16 ) is one selected from the group consisting of ammonium sulfate, iron chloride, sulfuric acid, nitric acid, hydrochloric acid, and a mixture thereof.
18 . The method of fabricating graphite films of claim 1 , wherein a carbonization temperature of the Step ( 17 ) is controlled within a range of 600˜1500° C.
19 . The method of fabricating graphite films of claim 1 , wherein a graphitization temperature of the Step ( 17 ) is controlled within a range of 2000˜3300° C., and preferably within a range of 2500˜3000° C.