Filament dispersion process
A method of spreading fibers of a tow including heat treating a fibrous preform having a plurality of tows and a resin mixture including an alcohol soluble binder, washing the fibrous preform with a solution of water and a water-soluble binder such that the solution occupies an intra-tow space of the plurality of tows, freezing the solution in the intra-tow space of the plurality of tows, and freeze-drying the fibrous preform. The method also includes making a CMC from the fibrous preform with spread tows.
1 . A method of spreading fiber tows comprising:
subjecting a fibrous preform to heat treatment, the fibrous preform comprising a plurality of tows and a resin mixture comprising 15 wt % to 60 wt % of an alcohol soluble binder and a solvent, wherein said heat treatment is sufficient to remove at least 99% of the solvent,
washing the fibrous preform, after said heat treatment, with a solution of water and a water-soluble binder such that the solution occupies an intra-tow space of the plurality of tows,
freezing the solution in the intra-tow space of the plurality of tows, and
freeze-drying the fibrous preform including the frozen solution in the intra-tow space of the plurality of tows.
2 . The method of claim 1 , further comprising:
molding the fibrous preform into a predetermined shape prior to the heat treatment.
3 . The method of claim 1 , wherein the alcohol soluble binder is polyvinyl butyral (PVB).
4 . The method of claim 1 , wherein the water-soluble binder is polyvinyl alcohol (PVA).
5 . The method of claim 1 , wherein freeze-drying the fibrous preform provides a porous three-dimensional scaffold in the intra-tow space of the plurality of tows, wherein the three-dimensional scaffold comprises the water-soluble binder.
6 . The method of claim 1 , wherein washing the fibrous preform comprises removing char formed on the plurality of tows and within the intra-tow space of the plurality of tows resulting from the heat treatment.
7 . The method of claim 1 , further comprising: draining the fibrous preform after washing, wherein the draining does not remove all of the solution from the intra-tow space of the plurality of tows.
8 . The method of claim 1 , wherein the washing comprises an ultrasonication process.
9 . The method of claim 1 , further comprising:
heating the freeze dried fibrous preform to a temperature between 300° C. and 500° C. to remove the water-soluble binder.
10 . A method of manufacturing a ceramic matrix composite comprising:
subjecting a fibrous preform to a heat treatment, the fibrous preform comprising a plurality of tows and a resin mixture comprising 15 wt % to 60 wt % of an alcohol soluble binder and a solvent, wherein said heat treatment is sufficient to remove at least 99% of the solvent,
washing the fibrous preform, after said heat treatment, with a solution of water and a water-soluble binder such that the solution occupies an intra-tow space of the plurality of tows,
freezing the solution in the intra-tow space of the plurality of tows,
freeze-drying the fibrous preform including the frozen solution in the intra-tow space of the plurality of tows,
heating the freeze dried fibrous preform to remove the water-soluble binder, and
densifying the fiber preform after heating the fiber preform.
11 . The method of claim 10 , further comprising molding the fibrous preform into a predetermined shape prior to the heat treatment.
12 . The method of claim 10 , wherein the alcohol soluble binder is polyvinyl butyral (PVB).
13 . The method of claim 10 , wherein the water-soluble binder is polyvinyl alcohol (PVA).
14 . The method of claim 10 , wherein freeze-drying the fibrous preform provides a porous three-dimensional scaffold in the intra-tow space of the plurality of tows, and wherein the three-dimensional scaffold comprises the water-soluble binder.
15 . The method of claim 10 , wherein washing the fibrous preform comprises removing char formed on the plurality of tows and within the intra-tow space of the plurality of tows resulting from the heat treatment.
16 . The method of claim 10 , further comprising draining the fibrous preform with the solution after washing, wherein the draining does not remove the solution from the intra-tow space of the plurality of tows.
17 . The method of claim 10 , wherein the washing comprises an ultrasonication process.
18 . The method of claim 10 , wherein the heat treatment comprises heating the fibrous preform to a temperature of 75° C. to 260° C.