Process for slip casting textured tubular structures

• US 6,335,065 B1
• Filed: 11/10/1999
• Issued: 01/01/2002
• Est. Priority Date: 11/14/1994
• Status: Expired due to Fees

• Current Assignee: Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Original Assignee: Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Inventors: Bowman, Keith J., Steinlage, Greg A., Trumble, Kevin P.
• Primary Examiner(s): DYE, RENA
• Application Number:
  US09/438,011
• Time in Patent Office: 783 Days
• Field of Search: 428/34.4, 428/34.5, 428/34.6, 505/490, 505/501, 505/739, 505/741, 505/492, 264/86, 264/108, 264/637
• US Class Current: 428/34.5
• CPC Class Codes: B28B 1/28 involving rotation of the mould about a centrifugal axis
• CPC Class Codes: B28B 21/08 by slip-casting; Moulds therefor
• CPC Class Codes: B28B 7/38 Treating surfaces of moulds, cores, or mandrels to prevent sticking
• CPC Class Codes: H10N 60/0268 of devices comprising copper oxide
• CPC Class Codes: Y10S 505/739 Molding, coating, shaping, or casting of superconducting material
• CPC Class Codes: Y10S 505/741 Coating or casting onto a substrate, e.g. screen printing, tape casting
• CPC Class Codes: Y10T 428/1314 Contains fabric, fiber particle, or filament made of glass, ceramic, or sintered, fused, fired, or calcined metal oxide, or metal carbide or other inorganic compound [e.g., fiber glass, mineral fiber, sand, etc.]
• CPC Class Codes: Y10T 428/1317 Multilayer [continuous layer]

Abstract

A process for centrifugal slip casting a textured hollow tube. A slip made up of a carrier fluid and a suspended powder is introduced into a porous mold which is rotated at a speed sufficient to create a centrifugal force that forces the slip radially outward toward the inner surface of the mold. The suspended powder, which is formed of particles having large dimensional aspect ratios such as particles of superconductive BSCCO, settles in a textured fashion radially outward toward the mold surface. The carrier fluid of the slip passes by capillary action radially outward around the settled particles and into the absorbent mold. A layer of mold release material is preferably centrifugally slip cast to cover the mold inner surface prior to the introduction of the BSCCO slip, and the mold release layer facilitates removal of the BSCCO greenbody from the mold without fracturing.

Claims

1. A highly textured hollow tube prepared by the process of:

providing an absorbent hollow mold rotatable about its axis, said mold comprising a porous inner surface;

rotating said mold about its axis at a speed sufficient to produce a centrifugal force sufficient to force an introduced slip radially outward toward said inner surface of said mold;

centrifugally casting a slip within said rotating mold, wherein said slip comprises a carrier fluid and a suspended powder, wherein substantially all of said suspended powder comprises powder particles having large dimensional aspect ratios, wherein during centrifugal casting said powder particles settle in a textured arrangement toward said mold inner surface with the long dimensions of said particles aligned substantially along an axis, wherein during centrifugal casting and after powder particle settlement said carrier fluid further textures said settled particles by passing by capillary action radially outward around said settled particles, through said inner surface, and into said mold to be absorbed thereby, whereby a cast tubular greenbody is formed of settled powder particles;

stopping rotation of said mold; and

removing said greenbody from said mold.

2. The highly textured hollow tube of claim 1 wherein said suspended powder particles comprise BSCCO.

3. The highly textured hollow tube of claim 1 wherein said suspended powder particles comprise a plate morphology.

4. The highly textured hollow tube of claim 1 wherein the process further comprises the step of centrifugally slip casting a mold release layer against said mold inner surface prior to the centrifugal casting of the slip having suspended powder particles with large dimensional aspect ratios.

5. The highly textured hollow tube of claim 4 wherein the mold release layer comprises silver.

6. The highly textured hollow tube of claim 1 wherein the process further comprises the step of centrifugally slip casting at least one additional settled powder layer after casting the slip having suspended powder particles with large dimensional aspect ratios.

7. A highly textured tube prepared by the process of:

providing an absorbent hollow mold rotatable about its axis, said mold comprising a porous inner surface;

rotating said mold about its axis at a speed sufficient to produce a centrifugal force sufficient to force an introduced slip radially outward toward said inner surface of said mold;

centrifugally casting a slip within said rotating mold, wherein said slip comprises a carrier fluid and a suspended powder, wherein substantially all of said suspended powder comprises powder particles having large dimensional aspect ratios, wherein during centrifugal casting said powder particles settle in a textured arrangement toward said mold inner surface, wherein during centrifugal casting and after powder particle settlement said carrier fluid further textures said settled particles by passing by capillary action radially outward around said settled particles, through said inner surface, and into said mold to be absorbed thereby, whereby a cast tubular greenbody is formed of settled powder particles;

centrifugally slip casting at least one additional settled powder layer after casting said slip having suspended powder particles with large dimensional aspect ratios;

stopping rotation of said mold; and

removing said greenbody from said mold.