# US 5,700,411 A · Method for the fabrication of threaded ceramic parts

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- Number: US 5,700,411 A
- Document ID: US5700411A
- Status: Granted
- Kind: A
- Application number: 08/752,133
- Filed: 1996-11-21
- Granted: 1997-12-23
- Earliest claimed: 1996-11-21
- Assignees: Eastman Kodak Company
- Inventors: Edward P. Furlani; Dilip K. Chatterjee; Syamal K. Ghosh
- Web page: https://patentgrep.com/patent/US5700411A

## CPC

- C04B 35/622: Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- B28B 7/342: {which are at least partially destroyed, e.g. broken, molten, before demoulding; Moulding surfaces or spaces shaped by, or in, the ground, or sand or soil, whether bound or not; Cores consisting at least mainly of sand or soil, whether bound or not}
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- B28B: SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER (foundry moulding B22C; working stone or stone-like material B28D; shaping of substances in a plastic state, in general B29C; making layered products not composed wholly of these substances B32B)

## Abstract

A method of fabricating a threaded micro-ceramic part, includes the steps of: forming a sacrificial fiber, having a melting temperature greater than the sintering temperature of the ceramic material to be used to mold the threaded micro-ceramic part; winding the sacrificial fiber about a sintered ceramic plug generally in the shape of the threaded micro-ceramic part with the winded fiber corresponding to threads; providing a green ceramic housing formed with a passage and placing the plug with the wound sacrificial fiber in the passage. The method further includes the steps of sintering the green ceramic housing containing the wound sacrificial fiber plug to provide a unitary structure; removing the wound sacrificial fiber from the unitary structure forming a threaded cavity in the unitary structure; removing the plug leaving behind a threaded mold which is adapted to form the threaded micro-ceramic part; compressing ceramic powder within the threaded mold; and sintering the threaded mold containing the compressed ceramic powder to harden the sintered ceramic powder to form the threaded micro-ceramic part whereby during sintering the formed threaded micro-ceramic part shrinks to permit its removal from the mold.

## Claims

### Claim 1

A method of fabricating a threaded micro-ceramic part, comprising the steps of:
a) forming a sacrificial fiber having a melting temperature;
b) winding the sacrificial fiber about a sintered ceramic plug generally in a shape of the threaded micro-ceramic part with the wound fiber corresponding to threads;
c) providing a green ceramic housing formed with a passage and placing the plug with the wound sacrificial fiber within the passage;
d) sintering at a temperature the green ceramic housing containing plug with the wound sacrificial fiber whereby the ceramic housing shrinks thereby converting the passage to a threaded cavity, wherein said sintering temperature is lower than the melting temperature of the sacrificial fiber;
e) removing the wound sacrificial fiber from the sintered housing;
f) removing the plug leaving behind a threaded mold which is adapted to form the threaded micro-ceramic part;
g) compressing ceramic powder within the threaded mold; and
h) sintering the compressed ceramic powder within said threaded mold to harden the ceramic powder to form the threaded micro-ceramic part whereby during sintering the formed threaded micro-ceramic part shrinks to permit its removal from the threaded mold.

### Claim 2 (depends on 1)

The method for fabricating the threaded micro-ceramic part according to claim 1 wherein the sacrificial fiber is removed by etching.

### Claim 3 (depends on 1)

The method for fabricating the threaded micro-ceramic part according to claim 1 wherein the sacrificial fiber is removed by increasing the temperature of the unitary structure above the melting point of the sacrificial fiber.

### Claim 4 (depends on 1)

The method for fabricating the threaded micro-ceramic part according to claim 1, wherein the sacrificial fiber is tungsten, molybdenum, or tantalum.

### Claim 5 (depends on 1)

The method according to claim 1 wherein the ceramic powder is a ceramic material selected from the group consisting of Al.sub.2 O.sub.3, ZrO.sub.2, AlN, BN, MgO, Al.sub.2 O.sub.3 --ZrO.sub.2 and other oxide and non-oxide composites thereof.

### Claim 6 (depends on 1)

The method according to claim 1 wherein the ceramic housing is formed from a ceramic material selected from the group consisting of Al.sub.2 O.sub.3, ZrO.sub.2, AlN, BN, MgO, Al.sub.2 O.sub.3 --ZrO.sub.2 and other oxide and non-oxide composites thereof.

### Claim 7 (depends on 1)

The method according to claim 1 wherein the ceramic plug is formed from a ceramic material selected from the group consisting of Al.sub.2 O.sub.3, ZrO.sub.2, AlN, BN, MgO, Al.sub.2 O.sub.3 --ZrO.sub.2 and other oxide and non-oxide composites thereof.