Mullite shell systems for investment castings and methods

Patent metadata

Field	Value
Publication number	US-12208439-B2
Application number	US-202418624310-A
Country	US
Kind code	B2
Filing date	Apr 2, 2024
Priority date	Jul 15, 2019
Publication date	Jan 28, 2025
Grant date	Jan 28, 2025

Abstract

A mullite shell mold for casting includes a facecoat layer containing ceramic flour. The mullite shell mold also includes a first layer disposed on the facecoat layer. The first layer can contain sintered ceramic media. The facecoat layer and the first layer can each contain less than 1 wt % crystalline silica.

First claim

What is claimed is:

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 bauxite particles having a mesh size from about 10 mesh to about 100 mesh.

2. The shell mold of claim 1 , wherein the shell mold comprises substantially no crystalline silica.

3. The shell mold of claim 1 , wherein the shell mold comprises substantially no fused silica.

4. The shell mold of claim 1 , wherein the shell mold comprises substantially no zircon.

5. The shell mold of claim 1 , further comprising:
an intermediate layer overlaying the first layer, the intermediate layer comprising ceramic flour; and
a second layer overlaying the intermediate layer, the second layer comprising a second sintered ceramic media.

6. The shell mold of claim 5 , wherein the second layer and the intermediate layer comprise sintered kaolin, sintered bauxite, or sintered alumina or any combination thereof.

7. The shell mold of claim 6 , wherein the second sintered ceramic media are sintered, substantially round and spherical particles having a size from about 10 mesh to about 100 mesh.

8. 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 bauxite particles having a mesh size from about 10 mesh to about 100 mesh.

9. The method of claim 8 , wherein the ceramic flour consists essentially of sintered alumina, sintered bauxite, or sintered kaolin, or any mixture thereof.

10. The method of claim 8 , wherein the ceramic flour has a specific gravity of about 2.5 to about 4.0.

11. The method of claim 8 , wherein the sintered material of the stucco material has the substantially the same composition as the ceramic flour.

12. The method of claim 8 , wherein the facecoat layer has a thickness of about 0.01 inch to about 0.5 inch.

13. The method of claim 8 , further comprising:
depositing an intermediate layer overlaying the first layer, the intermediate layer comprising ceramic flour; and
depositing a second layer overlaying the intermediate layer, the second layer comprising a second sintered ceramic media.

14. The method of claim 13 , wherein the second layer and the intermediate layer independently comprise sintered kaolin, sintered bauxite, sintered alumina, or a combination thereof.

15. The method of claim 8 , further comprising drying the mold at a temperature of about 800° C. to about 1230° C.

Assignees

• Carbo Ceramics Inc

Inventors

• Janson Ray
• Canfield Ryan

Classifications

• B22C9/04 Primary

  Use of lost patterns · CPC title

• B22C7/02

  Lost patterns · CPC title

• B22C1/183

  Sols, colloids or hydroxide gels · CPC title

• B22C1/165

  in the manufacture of multilayered shell moulds · CPC title

• B22C1/00

  Compositions of refractory mould or core materials; Grain structures thereof (refractory materials in general C04B35/00); Chemical or physical features in the formation or manufacture of moulds · CPC title