Discrete solidification of melt infiltration

Patent metadata

Field	Value
Publication number	US-11046618-B2
Application number	US-201815967664-A
Country	US
Kind code	B2
Filing date	May 1, 2018
Priority date	May 1, 2017
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

Abstract

A ceramic matrix composite (CMC) is formed by infiltrating a metal or alloy into a fiber preform in a reactor or furnace that is separated into multiple discrete temperature zones. The gradual cooling of the CMC is controlled, such that upon solidification, a narrow, planar, solidification front is created which allows the expanding metal or alloy to move into a hotter section of the fiber preform, opposed to the surface of the CMC. A discrete solidification front is established that moves through the ceramic matrix composite (CMC) as the composite cools.

First claim

What is claimed is:

1. A method of producing a ceramic matrix composite (CMC), the method comprising:
providing a fiber preform;
providing first and second wick materials on opposing surfaces of the fiber preform such that each of the first and second wick materials is in contact with at least a portion of a top surface or a bottom surface of the fiber preform;
combining the fiber preform and the first wick material with a metal or alloy, wherein the metal or alloy is contained within a hollowed-out region of the first wick material or in a crucible;
providing a reactor that comprises a cold zone, a preheat zone, and a hot zone, wherein adjacent zones are separated from each other by one or more thermal barriers or baffles;
permitting the combination of the fiber preform, the first and second wick materials, and the crucible to enter the cold zone of the reactor;
transferring the combination of the fiber preform, the first and second wick materials, and the crucible through the cold zone, the preheat zone and the hot zone at a predetermined rate;
forming a molten metal bath from the metal or alloy while the crucible is in the hot zone;
infiltrating the first wick material and the fiber preform with the metal or alloy from the molten metal bath; and
allowing the metal or alloy that has infiltrated in to the fiber preform to solidify, thereby forming the ceramic matrix composite,
wherein a discrete solidification front is established that moves through the ceramic matrix composite from the top surface to the bottom surface or from the bottom surface to the top surface as the ceramic matrix composite cools, and
wherein, as the metal or alloy solidifies during the cooling, the second wick material captures excess metal or alloy,
wherein the cold zone is a first cold zone, and further comprising a second cold zone downstream of the hot zone, and
wherein the discrete solidification front is established when the metal or alloy begins to cool during a transition from the hot section to the second cold zone.

2. The method according to claim 1 , wherein the method further comprises:
removing the first and second wick materials from being in contact with the ceramic matrix composite; and
performing one or more finishing operations on the ceramic matrix composite.

3. The method according to claim 1 , wherein the fiber preform comprises a plurality of silicon carbide (SiC) fibers, silicon nitride fibers, alumina fibers, mullite fibers, zirconia fibers, carbon fibers, or a combination thereof; the plurality of fibers being woven into a shape that resembles the ceramic matrix composite to be produced;
optionally, wherein the fiber preform further comprises a fiber coating with or without subsequent rigidization with a ceramic material.

4. The method according to claim 1 , wherein the metal or alloy comprises silicon, and optionally, a ceramic is present in the form of silicon carbide.

5. The method according to claim 4 , wherein a predetermined temperature in the hot zone is about 20° C. to about 50° C. greater than a melting temperature of the metal or alloy;
wherein a temperature of the preheat zone is between about 25° C. to about 150° C. lower than the melting temperature of the metal or alloy;
wherein a temperature of the cold zone is between about ambient or room temperature up to about 200° C. below the melting temperature of the metal or alloy.

6. The method according to claim 1 , wherein the preheat zone, the hot zone, and optionally, the cold zone are placed under a vacuum.

7. The method according to claim 1 , wherein the combination of the fiber preform, the first and second wick materials, and the crucible are coupled with and moved by a rod, a pulley system, an actuator system, or a cable, such that the predetermined rate at which the combination is moved is between about 0.4 mm/min (1 in/hr) to about 4.2 mm/min (10 in/hr).

8. The method according to claim 1 , wherein the infiltration of the metal or alloy into the first wick material and into the fiber preform is due to capillary forces, gravity, or a combination thereof.

9. The method according to claim 1 , wherein one or both of the first and second wick materials have a larger pore size or pore volume than the fiber preform.

10. The method according to claim 1 , wherein one or both of the first and second wick materials comprise a felt material, carbon foam, a textile, or a mixture thereof.

11. The method according to claim 1 , wherein the method incorporates an overall impurity level derived from the infiltration of the molten metal or alloy of less than 20 ppm.

Assignees

• Rolls Royce High Temperature Composites Inc
• Rolls Royce Corp

Inventors

• Shinavski Robert
• Doyle Joseph
• Ritchey Andrew
• Harris Stephen

Classifications

• C04B35/80

  Fibres, filaments, whiskers, platelets, or the like · CPC title

• C04B35/573 Primary

  obtained by reaction sintering {or recrystallisation} · CPC title

• C04B2235/5228

  Silica and alumina, including aluminosilicates, e.g. mullite · CPC title

• C04B2235/616

  Liquid infiltration of green bodies or pre-forms · CPC title

• C04B2235/5244

  Silicon carbide · CPC title