Method of making honeycomb structures

• US 4,293,513 A
• Filed: 05/12/1975
• Issued: 10/06/1981
• Est. Priority Date: 11/02/1970
• Status: Expired due to Term

• Current Assignee: Englehard Corp.
• Original Assignee: Engelhard Minerals & Chemicals Corporation
• Inventors: Langley, Robert C., Myers, Herbert, Abrash, Muriel
• Primary Examiner(s): Parrish, John
• Application Number:
  US05/576,640
• Time in Patent Office: 2,339 Days
• Field of Search: 264/60, 264/61, 264/62, 264/132, 264/308, 264/173, 101/129
• US Class Current: 264/630
• CPC Class Codes: B28B 13/022 Feeding several successive layers, optionally of different materials
• CPC Class Codes: B28B 3/20 wherein the material is extruded extrusion moulding of plastics B29C48/00
• CPC Class Codes: B28B 3/269 For multi-channeled structures, e.g. honeycomb structures
• CPC Class Codes: B29C 48/001 Combinations of extrusion moulding with other shaping operations
• CPC Class Codes: B29C 48/11 comprising two or more partially or fully enclosed cavities, e.g. honeycomb-shaped
• CPC Class Codes: B29C 48/13 Articles with a cross-section varying in the longitudinal direction, e.g. corrugated pipes
• CPC Class Codes: B29C 48/288 in solid form, e.g. powder or granules
• CPC Class Codes: B29K 2105/16 Fillers
• CPC Class Codes: B29K 2995/0021 Multi-coloured
• CPC Class Codes: B29L 2031/608 Honeycomb structures
• CPC Class Codes: B44C 3/025 Superimposing layers to produce ornamental relief structures
• CPC Class Codes: C04B 35/632 Organic additives
• CPC Class Codes: C04B 38/0006 Honeycomb structures from one or more corrugated sheets by winding or stacking C04B38/0083
• CPC Class Codes: Y10T 428/24149 Honeycomb-like

Abstract

Monolithic honeycomb structures are made by heating to a fluid condition an admixture comprising an inorganic powder and a temporary vehicle, forcing the fluid admixture through a stencil having a plurality of masking islands thereby forming a thin lamina beneath the stencil which is cooled immediately to form an essentially solid structure. This process is repeated to form a composite of successive cohered laminae thereby forming a monolithic honeycomb structure, which is heated to remove the vehicle and subsequently sintered to form a self-supporting honeycomb structure.

Claims

1. A process for making a monolithic structure having a plurality of channels comprising:

(a) admixing an inorganic powder and a temporary vehicle to provide an admixture which is solid and self-supporting at room temperature and is fluid at an elevated temperature, said inorganic powder being capable of being sintered;

(b) depositing the admixture on a stencil having a plurality of masking islands;

(c) providing the admixture deposited on said stencil in a heated fluid condition;

(d) forcing the resulting heated, fluidized admixture through said stencil, thereby forming a thin lamina beneath and in contact with the bottom of said stencil, and immediately cooling said lamina by loss of heat to the ambient surroundings to form a reproduction of said stencil such that said masking islands define openings in said lamina;

(e) repeating step (d) at least about 20 times in a manner such that each lamina is formed on the top surface of the lamina previously formed so as to produce successive, overlying, cohesive laminae forming a substantially monolithic structure having a plurality of channels formed therethrough, said channels having a cross-sectional area defined by said openings provided by said masking islands, said successive, overlying, cohesive laminae being formed as a continuous structure of at least about 1/4 inch in length;

(f) heating gradually the monolithic structure to remove said vehicle and to prevent distortion of the monolithic structure; and

(g) thereafter heating said monolithic structure to a sintering temperature, and then permitting the monolithic structure to cool, said structure exhibiting a condition of mechanical strength sufficient to be self-supporting.

2. A process for making a monolithic honeycomb structure comprising:

(a) admixing an inorganic powder and a temporary thermoplastic organic vehicle to provide an admixture which is solid and self-supporting at room temperature and is fluid at an elevated temperature, said inorganic powder being capable of being sintered;

(b) depositing the admixture on the upper surface of horizontal stencil having a plurality of masking islands;

(c) providing the admixture deposited on said stencil in a heated fluid condition;

(d) forcing the resulting heated, fluidized admixture through said stencil, thereby forming a thin lamina beneath and in contact with the base of said stencil and immediately cooling said lamina by loss of heat to the ambient surroundings to solidify said lamina and form a reproduction of said stencil in contact with the base of said stencil, said reproduction of said stencil being such that said masking islands define openings in said lamina;

(e) repeating step (d) at least about 20 times in a manner such that each lamina is formed on the top surface of the lamina previously formed so as to produce successive, overlying cohesive laminae forming a substantially monolithic honeycomb structure, said honeycomb structure having a plurality of channels formed therethrough, said channels having a cross-sectional area defined by said openings provided by said masking islands, said successive, overlying, cohesive laminae being formed as a continuous structure which is at least about 1/4 inch in length;

(f) heating gradually the monolithic honeycomb structure to remove said vehicle and to prevent distortion of the monolithic honeycomb structure; and

(g) thereafter heating said monolithic honeycomb structure to a sintering temperature and then permitting the monolithic honeycomb structure to cool, said honeycomb structure exhibiting a condition of mechanical strength sufficient to be self-supporting.

3. The process of claim 2 wherein said vehicle comprises a wax or wax-like substance.

4. The process of claim 2 wherein said vehicle comprises stearic acid.

5. A process of claim 2 wherein said masking islands are substantially symmetrically arranged.

6. A process of claim 5 wherein said masking islands are substantially uniformly spaced relative to each other.

7. A process of claim 2 wherein said inorganic powder is selected from the group consisting of alumina, zirconia, aluminosilicates, tungsten, silver, ruthenium and mixtures and combinations thereof.

8. The process of claim 2 wherein the resultant structure has more than about 100 channels per square inch of cross-section.

9. The process of claim 2 wherein during step (e) the bottom of the first-formed lamina comes into contact with a horizontal substrate below said stencil and originally spaced therefrom, and said substrate is lowered in relation to said stencil after each deposition of a lamina.

10. The process of claim 2 wherein during step (e) the initially formed lamina exiting the base of said stencil is deposited on a horizontal substrate located below the base of said stencil and originally spaced therefrom, and the substrate is lowered in relation to said stencil after each deposition of a lamina, and said substrate is subsequently removed from the resulting honeycomb structure before step (f).