GB2147891A - Preparation of silicon carbide fibers - Google Patents
Preparation of silicon carbide fibers Download PDFInfo
- Publication number
- GB2147891A GB2147891A GB08424355A GB8424355A GB2147891A GB 2147891 A GB2147891 A GB 2147891A GB 08424355 A GB08424355 A GB 08424355A GB 8424355 A GB8424355 A GB 8424355A GB 2147891 A GB2147891 A GB 2147891A
- Authority
- GB
- United Kingdom
- Prior art keywords
- fibers
- mixture
- rayon
- sic
- silica
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/62227—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/90—Carbides
- C01B32/914—Carbides of single elements
- C01B32/956—Silicon carbide
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/90—Carbides
- C01B32/914—Carbides of single elements
- C01B32/956—Silicon carbide
- C01B32/963—Preparation from compounds containing silicon
- C01B32/97—Preparation from SiO or SiO2
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
Abstract
Silicon carbide fibers suitable for use in the fabrication of dense, high-strength, high-toughness SiC composites or as thermal insulating materials in oxidizing environments are fabricated by a method wherein a mixture of short-length rayon fibers and colloidal silica is homogenized in a water slurry. Water is removed from the mixture by drying in air at 120 DEG C and the fibers are carbonized by (pyrolysis) heating the mixture to 800-1000 DEG C in argon. The mixture is subsequently reacted at 1550-1900 DEG C in argon to yield pure ss-SiC fibers.
Description
SPECIFICATION
Preparation of silicon carbide fibres
This invention resulted from a contract with the
United States Department of Energy and relates to an simplified process for preparing silicon carbide fibers.
There is an increasing interest in the appiication of SiC fibers to reinforce ceramics, metals and plastics because of the high thermal stability, fa- vourable mechanical properties, and high oxidation resistance at elevated temperatures (up to 1500 C) of this material. Present methods for preparing SiC fibers focus on the use of organic polycarbosilanes. One such method involves the conversion of an organometallic polymer (obtained from docieca- methylcyclohexasilane) into an organic SiC fiber by heat treatment. In general, the previously used methods are complex, require relatively expensive starting materials, and result in a high cost product.The development of a less complex method that requires less expensive, more readily available starting materials could supply the increasing demand for SiC fibers.
Summary of the invention
It is the object of this invention to provide a simplified, relatively low cost method for preparing
SiC fibers suitable for use in the fabrication of dense, high-strength, high-toughness SiC composites or as thermal insulating materials in oxidizing environments. More specifically, the invention lies in carbonizing rayon fibers by pyrolysis and reacting the carbon fibers with colioidal silica and comprises the step of:
1. homogenizing in water a mixture of shortlength rayon fibers (750 > m long, 121lm diam.) and colloidal silica;
2. removing the water by drying the mixture in air at 120 C.
3. heating the mixture at 800-1000 C in argon to carbonize the rayon fibres;
4. reacting the mixture in argon at 1550-1900 C to yield pure SiC fibers.
Experimental tests of this method show the product fibers to be ss SiÇ with no other detactable crystalline phases. The demonstrated simplicity of this method indicates an adaptability to a scaledup commercial process.
Detailed description of a preferred embodiment of the invention
As shown in Fig. 1, continuous rayon filament is precision chopped to short-length fibers (e.g.
750,um long) which are mixed in water with colloi- dal silica in a weight ratio of three parts of rayon to one part of silica. The amount of water used is typically about one gallon for 40 grams feed material. The mixture is dried in air at 120 C to remove water and carbonized by heating in Ar to 1000 C at a rate of 100 C per hour and then holding for 1 hour. The pyrolyzed mixture is reated at temperatures from 1500 to 1900 C for one to three hours in
Ar to form SiC fibers.
Example 1
Ten grams of colloidal silica (grade HS-5 from Cabot Corp., Boston, Mass.) were mixed with 30 grams of chopped rayon (750Fm long x 12pm diam, made by Beaunit Fiber Co., Elizabethtown,
Tennessee, and chopped by Microfiber Co., Paw- tucket, Rhode Island) in about 0.5 gallon of water in a Waring blender for about two minutes at low speedy The mixture was dried at 120 C in air for 16 hours and then pyrolyzed in argon by heating at a rate of 10D C per hour from room temperature to 1000 C and holding one hour.The final reaction was at 1575 C for three hours in Ar to form ss-SiC fibers.
Microscopic examination and x-ray diffraction re Sulks Indicated that the fibres made in the example were b-SiC with no other detachable crystalline phases. The SiC fibers appeared to retain the corrugated morphology of rayon fiber with rough ened-surface characteristics.
The extremely small particle size of the colloidal silica provides a large surface area for contact with the carbonized fibers for a complete reaction to form 3-SiC. The process is relatively simple, and both rayon fibers and colloidal silica are relatively inexpensive, thus providing a SiC fiber product of high quality at low cost.
It is expected that other refractory metal carbide fibers (titanium carbide for example) could be produced by this method by using the corresponding colloidai oxide and rayon at appropriate reaction temperatures.
1. A method of preparing silicon carbide fibers, comprising:
homogenizing in water a mixture of rayon fibers and colloidaí silica;
heating the homogenized mixture of rayon fibers and coliQidal silica to remove water therefrom;
heating the dried mixture of rayon fibers and colioidal silica in an inert atmosphere to carbonize the rayon fibers; and
reacting the mixture of carbonized rayon fibers and colloidai silica in an inert atmosphere to convert the carbonized rayon fibers to silicon carbide fibers.
2. The method of Claim 1 wherein the homogenized mixture of rayon fibers and colloidal silica is heated at a temperature of about 120 C to remove water therefrom.
3. The method of Claim 1 wherein the dried mixture of rayon fibers and colíoidal silica is heated to a temperature of about 800 C to about 100D C to carbonize the rayon fibers.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (4)
1. homogenizing in water a mixture of shortlength rayon fibers (750 > m long, 121lm diam.) and colloidal silica;
2. removing the water by drying the mixture in air at 120 C.
3. heating the mixture at 800-1000 C in argon to carbonize the rayon fibres;
4. The method of Claim 1 wherein the mixture of carbonized rayon fibers and colloidal silica is heated to a temperature of about 15500C to about 1900"C to convert the carbonized rayon fibers to silicon carbide fibers.
4. reacting the mixture in argon at 1550-1900 C to yield pure SiC fibers.
Experimental tests of this method show the product fibers to be ss SiÇ with no other detactable crystalline phases. The demonstrated simplicity of this method indicates an adaptability to a scaledup commercial process.
Detailed description of a preferred embodiment of the invention
As shown in Fig. 1, continuous rayon filament is precision chopped to short-length fibers (e.g.
750,um long) which are mixed in water with colloi- dal silica in a weight ratio of three parts of rayon to one part of silica. The amount of water used is typically about one gallon for 40 grams feed material. The mixture is dried in air at 120 C to remove water and carbonized by heating in Ar to 1000 C at a rate of 100 C per hour and then holding for 1 hour. The pyrolyzed mixture is reated at temperatures from 1500 to 1900 C for one to three hours in
Ar to form SiC fibers.
Example 1
Ten grams of colloidal silica (grade HS-5 from Cabot Corp., Boston, Mass.) were mixed with 30 grams of chopped rayon (750Fm long x 12pm diam, made by Beaunit Fiber Co., Elizabethtown,
Tennessee, and chopped by Microfiber Co., Paw- tucket, Rhode Island) in about 0.5 gallon of water in a Waring blender for about two minutes at low speedy The mixture was dried at 120 C in air for 16 hours and then pyrolyzed in argon by heating at a rate of 10D C per hour from room temperature to 1000 C and holding one hour.The final reaction was at 1575 C for three hours in Ar to form ss-SiC fibers.
Microscopic examination and x-ray diffraction re Sulks Indicated that the fibres made in the example were b-SiC with no other detachable crystalline phases. The SiC fibers appeared to retain the corrugated morphology of rayon fiber with rough ened-surface characteristics.
The extremely small particle size of the colloidal silica provides a large surface area for contact with the carbonized fibers for a complete reaction to form 3-SiC. The process is relatively simple, and both rayon fibers and colloidal silica are relatively inexpensive, thus providing a SiC fiber product of high quality at low cost.
It is expected that other refractory metal carbide fibers (titanium carbide for example) could be produced by this method by using the corresponding colloidai oxide and rayon at appropriate reaction temperatures.
1. A method of preparing silicon carbide fibers, comprising:
homogenizing in water a mixture of rayon fibers and colloidaí silica;
heating the homogenized mixture of rayon fibers and coliQidal silica to remove water therefrom;
heating the dried mixture of rayon fibers and colioidal silica in an inert atmosphere to carbonize the rayon fibers; and
reacting the mixture of carbonized rayon fibers and colloidai silica in an inert atmosphere to convert the carbonized rayon fibers to silicon carbide fibers.
2. The method of Claim 1 wherein the homogenized mixture of rayon fibers and colloidal silica is heated at a temperature of about 120 C to remove water therefrom.
3. The method of Claim 1 wherein the dried mixture of rayon fibers and colíoidal silica is heated to a temperature of about 800 C to about 100D C to carbonize the rayon fibers.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US54118883A | 1983-10-12 | 1983-10-12 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8424355D0 GB8424355D0 (en) | 1984-10-31 |
| GB2147891A true GB2147891A (en) | 1985-05-22 |
Family
ID=24158538
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08424355A Withdrawn GB2147891A (en) | 1983-10-12 | 1984-09-26 | Preparation of silicon carbide fibers |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS6099005A (en) |
| GB (1) | GB2147891A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2160186A (en) * | 1984-05-09 | 1985-12-18 | Central Glass Co Ltd | Method of continuously producing powder of silicon compound useful as ceramics material |
| GB2390603A (en) * | 2002-07-10 | 2004-01-14 | Advanced Composite Materials | Making silicon carbide fibers essentially devoid of whiskers |
| US7083771B2 (en) | 2002-07-10 | 2006-08-01 | Advanced Composite Materials Corporation | Process for producing silicon carbide fibers essentially devoid of whiskers |
| CN101850972A (en) * | 2010-06-21 | 2010-10-06 | 中国科学院山西煤炭化学研究所 | Method for preparing silicon carbide nano wires |
| US8648284B2 (en) | 2006-03-30 | 2014-02-11 | Advanced Composite Materials, Llc | Composite materials and devices comprising single crystal silicon carbide heated by electromagnetic radiation |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1145402A (en) * | 1965-10-23 | 1969-03-12 | Fmc Corp | Method of forming high temperature resistant structures and structures formed thereby |
-
1984
- 1984-09-26 GB GB08424355A patent/GB2147891A/en not_active Withdrawn
- 1984-10-09 JP JP59212415A patent/JPS6099005A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1145402A (en) * | 1965-10-23 | 1969-03-12 | Fmc Corp | Method of forming high temperature resistant structures and structures formed thereby |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2160186A (en) * | 1984-05-09 | 1985-12-18 | Central Glass Co Ltd | Method of continuously producing powder of silicon compound useful as ceramics material |
| GB2390603A (en) * | 2002-07-10 | 2004-01-14 | Advanced Composite Materials | Making silicon carbide fibers essentially devoid of whiskers |
| GB2390603B (en) * | 2002-07-10 | 2006-04-12 | Advanced Composite Materials | Silicon carbide fibers essentially devoid of whiskers and method for preparation thereof |
| US7041266B1 (en) | 2002-07-10 | 2006-05-09 | Advanced Composite Materials Corp. | Silicon carbide fibers essentially devoid of whiskers and products made therefrom |
| US7083771B2 (en) | 2002-07-10 | 2006-08-01 | Advanced Composite Materials Corporation | Process for producing silicon carbide fibers essentially devoid of whiskers |
| DE10330818B4 (en) * | 2002-07-10 | 2017-08-31 | Advanced Composite Materials Corp. | A method of producing discontinuous silicon carbide fibers substantially free of whiskers |
| US8648284B2 (en) | 2006-03-30 | 2014-02-11 | Advanced Composite Materials, Llc | Composite materials and devices comprising single crystal silicon carbide heated by electromagnetic radiation |
| US9688583B2 (en) | 2006-03-30 | 2017-06-27 | Advanced Composite Materials, Llc | Composite materials and devices comprising single crystal silicon carbide heated by electromagnetic radiation |
| CN101850972A (en) * | 2010-06-21 | 2010-10-06 | 中国科学院山西煤炭化学研究所 | Method for preparing silicon carbide nano wires |
| CN101850972B (en) * | 2010-06-21 | 2012-10-03 | 中国科学院山西煤炭化学研究所 | Method for preparing silicon carbide nano wires |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6099005A (en) | 1985-06-01 |
| GB8424355D0 (en) | 1984-10-31 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |