Spherical Fused Silica Compositions for Injection Molded Ceramic Cores and Methods of Making Parts Using Such Compositions
A single crystal ceramic core composition has an inorganic portion and an organic portion. The inorganic portion makes up about 85% by weight of the total weight of the ceramic core composition, and the organic portion makes up about 15% by weight of the total weight of the ceramic core composition. The inorganic portion includes about 94 to about 98% by weight spherical fused silica, and about 2 to about 6% by weight zircon. The organic portion includes about 84 to 88% by weight binder, about 1 to 2% by weight dye, about 6 to about 12% by weight surfactant, and about 1 to about 5% by weight polymeric fiber.
1 . A method of forming a turbine blade, the method comprising:
injecting a single crystal ceramic core composition into a mold to form a core having an internal profile of a turbine blade, the single crystal ceramic core composition including:
an inorganic portion including about 94 to about 98% by weight spherical fused silica, wherein the inorganic portion includes about 85% by weight of the total weight of the single crystal ceramic core composition; and
an organic portion including about 85 to about 89% by weight binder, wherein the organic portion includes about 15% by weight of the total weight of the single crystal ceramic core composition;
wherein the method further includes:
removing the core from the mold;
subjecting the core to a firing process to form a fused core;
inserting the fired cored into a die;
injecting liquid wax into an area between the fired core and the die to form a wax-covered fixed core, wherein the area between the fired core and the die has an external profile of the turbine blade;
removing the wax-covered fired core from the die;
forming a hardened ceramic shell around the wax-covered fired core;
removing the wax from between the hardened ceramic shell and the wax-covered fired core thereby forming a void between the hardened ceramic shell and the wax-covered fired core;
casting molten metal into the void and allowing the molten metal to cool to form a turbine blade, the wax-covered fired core being positioned within the turbine blade;
removing the hardened ceramic shell from the turbine blade; and
leaching the wax-covered fired core from within the turbine blade.
2 . The method of claim 1 , wherein the inorganic portion of the single crystal ceramic core composition includes about 96% by weight silica; and wherein the organic portion of the single crystal ceramic core composition includes about 87% binder.
3 . The method of claim 2 , wherein the inorganic portion of the single crystal ceramic core composition includes about 4% by weight zircon, and wherein the organic portion of the single crystal ceramic core composition includes about 13% by weight surfactant, dye, and polymer fiber.
4 . The method of claim 1 , wherein the inorganic portion of the single crystal ceramic core composition includes:
about 2 to about 6% by weight zircon; and
the organic portion of the single crystal ceramic core composition includes:
about 85 to about 88% by weight binder;
about 1 to about 2% by weight dye;
about 6 to about 12% by weight surfactant; and
about 1 to about 5% by weight polymeric fiber.
5 . The method of claim 4 , wherein:
the inorganic portion of the ceramic core composition includes:
about 95 to about 97% by weight spherical fused silica; and
about 3 to about 5% by weight zircon; and
the organic portion of the ceramic core composition includes:
about 86 to about 87% by weight binder;
about 1.2 to about 1.6% by weight dye;
about 8 to about 10% by weight surfactant; and
about 2 to about 4% by weight polymeric fiber.
6 . The method of claim 5 , wherein the spherical fused silica includes a plurality of particles, the plurality of particles having a particle size distribution of:
size of particle
% of particles
(in microns)
0-3
<1.16
0-1.5
1.16-1.64
0-1.8
1.64-2.31
1.4-2.4
2.31-3.27
1.6-2.6
3.27-4.62
2.0-3.0
4.62-6.54
2.9-3.9
6.54-9.25
4.4-5.4
9.25-13.08
6.6-7.6
13.08-18.50
9.2-10.2
18.50-26.16
12.7-13.7
26.16-37.0
16.9-17.9
37.0-52.33
16.7-17.7
52.33-74.0
9.6-10.6
74.0-104.7
3.9-4.9
104.7-148.0
1.4-2.4
148.0-209.3
1.4-2.4
209.3-296.0
0-2
>296.0.
7 . The method of claim 1 , wherein the spherical fused silica includes a plurality of particles, the plurality of particles having a particle size distribution of:
size of particle
% of particles
(in microns)
0-3
<1.16
0-1.5
1.16-1.64
0-1.8
1.64-2.31
1.4-2.4
2.31-3.27
1.6-2.6
3.27-4.62
2.0-3.0
4.62-6.54
2.9-3.9
6.54-9.25
4.4-5.4
9.25-13.08
6.6-7.6
13.08-18.50
9.2-10.2
18.50-26.16
12.7-13.7
26.16-37.0
16.9-17.9
37.0-52.33
16.7-17.7
52.33-74.0
9.6-10.6
74.0-104.7
3.9-4.9
104.7-148.0
1.4-2.4
148.0-209.3
1.4-2.4
209.3-296.0
0-2
>296.0.
8 . The method of claim 7 , wherein the binder includes a thermoplastic material.
9 . The method of claim 8 , wherein the thermoplastic material includes a paraffin-based wax.
10 . The method of claim 3 , wherein the surfactant includes sodium stearate, aluminum stearate, and oleic acid.
11 . The method of claim 3 , wherein the polymer fiber includes rayon fiber.
12 . The method of claim 1 , wherein the spherical fused silica includes a plurality of particles, the plurality of particles having a particle size distribution of:
size of particle
% of particles
(in microns)
0-2.7
<1.16
0.9-1.1
1.16-1.64
1.2-1.4
1.64-2.31
1.8-2.0
2.31-3.27
2.0-2.2
3.27-4.62
2.4-2.6
4.62-6.54
3.3-3.5
6.54-9.25
4.8-5.0
9.25-13.08
7.0-7.2
13.08-18.50
9.6-9.8
18.50-26.16
13.1-13.3
26.16-37.0
17.3-17.5
37.0-52.33
17.1-17.3
52.33-74.0
10.0-10.2
74.0-104.7
4.3-4.5
104.7-148.0
1.8-2.0
148.0-209.3
1.8-2.0
209.3-296.0
0-1.3
>296.0.
13 . The method of claim 1 , wherein the spherical fused silica includes a plurality of particles, the plurality of particles having a particle size distribution of:
size of particle
% of particles
(in microns)
0
<1.16
1
1.16-1.64
1
1.64-2.31
2
2.31-3.27
2
3.27-4.62
3
4.62-6.54
3
6.54-9.25
5
9.25-13.08
7
13.08-18.50
10
18.50-26.16
13
26.16-37.0
17
37.0-52.33
17
52.33-74.0
10
74.0-104.7
4
104.7-148.0
2
148.0-209.3
2
209.3-296.0
0
>296.0.
14 . A method of forming a turbine component, the method comprising:
injecting a single crystal ceramic core composition into a mold to form a core having an internal profile of a turbine component;
removing the core from the mold;
subjecting the core to a firing process to form a fused core;
inserting the fired cored into a die;
injecting liquid wax into an area between the fired core and the die to form a wax-covered fixed core, wherein the area between the fired core and the die has an external profile of the turbine component;
removing the wax-covered fired core from the die;
forming a hardened ceramic shell around the wax-covered fired core;
removing the wax from between the hardened ceramic shell and the fired core thereby forming a void between the hardened ceramic shell and the wax-covered fired core;
casting molten metal into the void and allowing the molten metal to cool to form the turbine component, the wax-covered fired core being positioned within the turbine component;
removing the hardened ceramic shell from the turbine component; and
leaching the wax-covered fired core from within the turbine component,
wherein the single crystal ceramic core composition includes:
an inorganic portion including about 85% by weight of the total weight of the ceramic core composition, the inorganic portion includes:
about 94 to about 98% by weight spherical fused silica; and
about 2 to about 6% by weight zircon; and
an organic portion including about 15% by weight of the total weight of the ceramic core composition, the organic portion including:
about 84 to about 88% by weight binder; and
about 12 to about 16% by weight surfactant and dye.
15 . The method of claim 14 , wherein the surfactant includes about 6 to about 12% by weight of the organic portion.
16 . The method of claim 14 , wherein the binder includes paraffin-based wax.
17 . The method of claim 14 , wherein the spherical fused silica includes about 96% by weight of the inorganic portion, and wherein the balance of the weight of the inorganic portion includes zircon.
18 . The method of claim 14 , wherein the binder includes about 86.5% by weight of the organic portion, and wherein the balance of the weight of the organic portion includes the surfactant and the dye.
19 . The method of claim 14 , wherein the surfactant includes sodium stearate, aluminum stearate, and fatty acid.
20 . The method of claim 14 , wherein the spherical fused silica includes a plurality of particles, the plurality of particles having a particle size distribution of:
size of particle
% of particles
(in microns)
0-3
<1.16
0-1.5
1.16-1.64
0-1.8
1.64-2.31
1.4-2.4
2.31-3.27
1.6-2.6
3.27-4.62
2.0-3.0
4.62-6.54
2.9-3.9
6.54-9.25
4.4-5.4
9.25-13.08
6.6-7.6
13.08-18.50
9.2-10.2
18.50-26.16
12.7-13.7
26.16-37.0
16.9-17.9
37.0-52.33
16.7-17.7
52.33-74.0
9.6-10.6
74.0-104.7
3.9-4.9
104.7-148.0
1.4-2.4
148.0-209.3
1.4-2.4
209.3-296.0
0-2
>296.0.