US 11,945,024 B2
Mullite shell systems for investment castings and methods
Ray Janson, Houston, TX (US); and Ryan Canfield, Houston, TX (US)
Assigned to CARBO CERAMICS INC., Houston, TX (US)
Appl. No. 17/597,627
Filed by CARBO CERAMICS INC., Houston, TX (US)
PCT Filed Jul. 15, 2020, PCT No. PCT/US2020/042091
§ 371(c)(1), (2) Date Jan. 14, 2022,
PCT Pub. No. WO2021/011624, PCT Pub. Date Jan. 21, 2021.
Claims priority of provisional application 62/874,223, filed on Jul. 15, 2019.
Prior Publication US 2022/0234095 A1, Jul. 28, 2022
Int. Cl. B22C 3/00 (2006.01); B22C 7/02 (2006.01); B22C 9/04 (2006.01)
CPC B22C 3/00 (2013.01) [B22C 7/02 (2013.01); B22C 9/04 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A shell mold, the shell mold comprising:
a facecoat layer comprising ceramic flour; and
a first layer overlaying the facecoat layer, the first layer comprising sintered ceramic media, wherein:
the facecoat layer and the first layer each contain less than 1 wt % crystalline silica, and
the sintered ceramic media comprises sintered, substantially round and spherical kaolin particles having a mesh size from about 10 mesh to about 100 mesh.
 
12. A method of manufacturing a casting mold, comprising:
introducing a ceramic flour with a colloidal silica to provide a facecoat slurry;
depositing the facecoat slurry onto a pattern comprising a thermoplastic material to provide a facecoat layer disposed on the pattern; and
depositing a stucco material onto the facecoat layer to provide a first layer disposed on the facecoat layer, the stucco material comprising sintered, substantially round and spherical kaolin particles having a mesh size from about 10 mesh to about 100 mesh.