EP0463050A1 - Process - Google Patents
ProcessInfo
- Publication number
- EP0463050A1 EP0463050A1 EP19900904884 EP90904884A EP0463050A1 EP 0463050 A1 EP0463050 A1 EP 0463050A1 EP 19900904884 EP19900904884 EP 19900904884 EP 90904884 A EP90904884 A EP 90904884A EP 0463050 A1 EP0463050 A1 EP 0463050A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- process according
- range
- granules
- particles
- carbon
- 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- Withdrawn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
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- 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
- C01P2004/50—Agglomerated particles
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
Definitions
- This invention relates to the production of silicon carbide powder for use in powder compaction
- Ceramic powders are finding increasing usage in the manufacture of engineering components as a replacement for metal. For example, it has been reported that an internal combustion engine has been produced in which such items as the cylinder block and pistons have been produced from ceramic materials, thereby obviating the need for lubrication.
- a typical specification for a silicon carbide powder for this purpose requires that it should be in the form of ß-silicon carbide, that it should have a low level, e.g. less than about 2% by weight, of by-product impurities, such as silicon dioxide, carbon and silicon, and that it should have a small range of size distribution.
- a low level e.g. less than about 2% by weight
- by-product impurities such as silicon dioxide, carbon and silicon
- 90% or more of the particles should lie in the range 0.1 to 10 ⁇ m, whilst it is preferred that over 95% of particles should lie in the range 0.1 to 5 ⁇ m.
- Particles of regular shape, e.g. spherical particles are preferred.
- Silicon carbide can be produced in lump form by reactions of quartz and coke in an electric furnace. The resulting lumps of silicon carbide can then be milled and the appropriate fraction of the required particle size can be selected for use as the powder for production of ceramic components. However, the resulting powder is relatively impure and its particles are of a very irregular shape.
- milling is a process requiring high cost equipment and consumes much energy.
- An alternative method of producing silicon carbide powder involves production of metallurgical grade silicon as a first step. This is then reacted, in a second step, with chlorine to produce silicon tetrachloride, which is'then purified in a third step. Next the purified silicon
- tetrachloride is reacted with a gaseous source of carbon, e.g. methane, to produce silicon carbide.
- a gaseous source of carbon e.g. methane
- the chlorine released is recovered and recycled for production of further silicon tetrachloride.
- the present invention accordingly seeks to provide a process whereby silicon carbide powder of appropriate morphology and purity for powder compaction can be produced in a simple manner and in relatively high yield without the need for production of silicon or silicon tetrachloride and without the need to include a milling step. It further seeks to provide a process whereby silicon dioxide can be converted directly by reaction with carbon to silicon carbide in particulate form, a high proportion of which is suitable for production of ceramic components.
- a process for the production of silicon carbide particles of a size suitable for manufacture of components by powder compaction which comprises forming granules of an intimate mixture comprising finely divided silica and carbon particles, said carbon particles being substantially
- spherical and substantially all having a diameter lying in the range of from about 0.1%pm up to about 10.0 ⁇ m, heating said granules by means of a plasma arc to a temperature in the range of from about 1950°K to about 2350°K, and
- One method of heating said granules is by means of a plasma arc.
- a particulate source of carbon in which the carbon particles substantially all have a diameter lying within a narrow range, for example in the range of from about 0.25 ⁇ m up to about 10 um, preferably in the range of from about 0.25pm up to about 5.0 ⁇ m.
- the finely divided silica comprises particles having a grain size in the range of from about 10um up to about 250um, typically 100um to about 200um.
- the finely divided silica may comprise
- particles having a grain size in the range of from about llOum to about 150um having a grain size in the range of from about llOum to about 150um.
- aqueous solution containing hydrofluoric acid.
- This aqueous solution may further contain nitric acid.
- a binding agent may be included in the mixture used to form the granules, such as water, silica gel or agents derived from hydrocarbons.
- hydrocarbonderived binding agents may be in liquid or wax form.
- the granules have a particle size in the range of from about 0.5 mm to about 2.5 mm. Heating can be effected in a d.c. transferred plasma arc furnace.
- reaction (A) begins to take place at about 1675°K whilst reaction (B) commences to become significant at about
- the size and shape of the silicon carbide particles produced by the process of the invention are determined largely by the size and shape of the carbon particles. Hence by appropriate choice of the particle size and shape of the particulate carbon it is possible to influence the size and shape of the resultant silicon carbide particles. Usually it will be preferred to select a source of carbon particles which are substantially
- Channel black and thermal black are suitable sources of particulate carbon to use in the process of the invention.
- a typical thermal black has substantially spherical particles with an average particle diameter of not more than about 0.35 ⁇ m, e.g. about 0.27 ⁇ m (about 270 nm).
- a silicon dioxide suitable for use in the process of the invention has an average particle size of not more than about 250um, e.g. about 125um, and is conveniently of substantially uniform particle size.
- the granules from an intimate mixture of silica and carbon in a
- stoichiometric or near stoichiometric molar ratio calculated on the basis of equations (A) and (B) above taken together, i.e. a 1:3 SiO 2 :C molar ratio or a ratio close thereto, for example a 1:3.2 SiO 2 :C molar ratio.
- the particles may comprise a core containing a 1:1 SiO 2 :C molar ratio or a ratio close thereto, corresponding to the stoichiometric ratio for equation (A) above, with a carbon rich outer layer.
- the quantity of carbon in the outer layer is preferably at least sufficient to provide a stoichiometric amount of carbon for equation (B) above.
- the ratio of the amount of carbon in the outer layer to the amount of SiO 2 in the core should desirably be at least about 2:1 on a molar basis.
- the granules may be formed by pelletising.
- the granules are substantially spherical and range in diameter from about 1 mm up to about 4 mm, e.g. about 1.5 mm to 2.0 mm.
- non-spherical granules e.g. cylindrical pellets
- Plasma arc furnace 1 is lined with MgO and
- Reference numeral 6 represents the anode.
- Crucible 2 is supported on graphite rods 7 and is surmounted by a graphite liner 8.
- Furnace 1 is itself fitted with a graphite liner 9.
- the furnace roof 10 is also made of graphite and
- a plasma forming gas such as argon
- argon can be introduced into the furnace at a pressure slightly above atmospheric pressure through the annular gap 12 between annular top 4 and cathode 5.
- Pellets of a mixture of silica and thermal black are fed to furnace 1 through feed ports 13 and are blown into furnace 1 by means of a non-oxidising gas, such as carbon monoxide or argon.
- Reference numeral 14 indicates diagrammatically the d.c. transferred are discharge that is formed when a suitably high d.c. voltage is struck between cathode 5 and anode 6.
- Make up water is introduced via line 17. This spray is indicated diagrammatically at 18 and is produced by forcing the water under pressure through nozzles 19.
- the water and silicon carbide particles collect in primary tank 20. Water is recycled to the top of the primary scrubber in line 21 by means of pump 22.
- the scrubbed gas passes on via duct 23 to secondary scrubber 24. Scrubbing water is pumped via line 25 to nozzles 26 to form spray 27. Water and further silicon carbide collects in secondary tank 28.
- the scrubbed gas is vented via line 29.
- Reference numeral 30 indicates a gas analyser sampling point.
- the material from the primary tank 20 consisted mainly of ß-silicon carbide and unreacted carbon plus some silicon and forsterite (Mg2SiO 4 ). No ⁇ -phase silicon carbide was detected. (The presence of forsterite in the material collected in the primary tank was ascribed to reaction of siliceous materials with magnesium from to furnace refractory). The major component of the minor amount of material collected in the secondary tank 28, was elemental silicon, together with some ß-silicon carbide, forsterite and silica. There was no carbon in this
- a sample of the powder product recovered from the primary tank was heated to 700°C in air for 15 hours in order to remove residual carbon.
- the resulting heated treated powder was then immersed in concentrated aqueous hydrofluoric acid for 12 hours in order to dissolve residual Si, SiO 2 and other impurities.
- the acid treated powder was then washed eight times with toluene and dried at 150°C for 12 hours in a fan-assisted oven.
- the dried powder was then characterised by measuring its surface area using nitrogen absorption by the well known BET method (i.e. the method developed by Brunnaurer, Emet and Teller) and by scanning electron microscopy (SEM).
- BET method i.e. the method developed by Brunnaurer, Emet and Teller
- SEM scanning electron microscopy
- the specific surface area of the sample was found to be 36.39 m 2 /g, corresponding to an average particle diameter of 51 nm (0.051um).
- the agglomerated particles appear spherical and free from sharp edges and corners.
- gas exiting furnace 1 through gas port 15 is passed to a bag plant for collection of the powder product.
Abstract
On décrit un procédé permettant de produire des particules de carbure de silicium ayant une dimension appropriée pour la production, par compactage de poudre, de composants, et consistant en premier lieu à former des granules d'un mélange intime se composant de particules de carbone et de dioxyde de silicium finement divisées, lesdites particules de carbone étant sensiblement sphériques et ayant sensiblement toutes un diamètre compris entre environ 0,1 mum et 10,0 mum, et en second lieu à chauffer lesdits granules à une température comprise entre environ 1950°K et 2350°K pour récupérer enfin le produit particulaire qui en résulte.We describe a process for producing silicon carbide particles having a size suitable for the production, by powder compacting, of components, and consisting first of all in forming granules of an intimate mixture consisting of carbon particles and of finely divided silicon dioxide, said carbon particles being substantially spherical and substantially all having a diameter between about 0.1 mum and 10.0 mum, and secondly heating said granules to a temperature between about 1950 ° K and 2350 ° K to finally recover the resulting particulate product.
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB898906044A GB8906044D0 (en) | 1989-03-16 | 1989-03-16 | Process |
GB8906044 | 1989-03-16 |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0463050A1 true EP0463050A1 (en) | 1992-01-02 |
Family
ID=10653436
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19900904884 Withdrawn EP0463050A1 (en) | 1989-03-16 | 1990-03-16 | Process |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0463050A1 (en) |
AU (1) | AU5273990A (en) |
GB (1) | GB8906044D0 (en) |
WO (1) | WO1990010595A1 (en) |
ZA (1) | ZA902045B (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103553043B (en) * | 2013-09-30 | 2015-04-22 | 陕西科技大学 | Preparation method for SiC nanometer microsphere with high specific surface area |
CN103539122B (en) * | 2013-10-12 | 2015-12-02 | 台州市一能科技有限公司 | A kind of preparation method of silicon carbide |
CN103553044B (en) * | 2013-10-12 | 2015-07-08 | 台州市一能科技有限公司 | Preparation method of high-purity silicon carbide |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL132104C (en) * | 1965-02-15 | |||
JPS5850929B2 (en) * | 1978-03-10 | 1983-11-14 | 株式会社東芝 | Method for manufacturing silicon carbide powder |
JPS63221842A (en) * | 1987-03-11 | 1988-09-14 | Nippon Steel Corp | Manufacturing method of metallic powder, metallic compound powder and ceramic powder and device thereof |
-
1989
- 1989-03-16 GB GB898906044A patent/GB8906044D0/en active Pending
-
1990
- 1990-03-16 AU AU52739/90A patent/AU5273990A/en not_active Abandoned
- 1990-03-16 WO PCT/GB1990/000395 patent/WO1990010595A1/en not_active Application Discontinuation
- 1990-03-16 EP EP19900904884 patent/EP0463050A1/en not_active Withdrawn
- 1990-03-16 ZA ZA902045A patent/ZA902045B/en unknown
Non-Patent Citations (1)
Title |
---|
See references of WO9010595A1 * |
Also Published As
Publication number | Publication date |
---|---|
GB8906044D0 (en) | 1989-04-26 |
ZA902045B (en) | 1990-12-28 |
WO1990010595A1 (en) | 1990-09-20 |
AU5273990A (en) | 1990-10-09 |
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Legal Events
Date | Code | Title | Description |
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
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17P | Request for examination filed |
Effective date: 19910909 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE CH DE DK ES FR GB IT LI LU NL SE |
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RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: NADEN, DAVID 47 SCALBY GROVE Inventor name: BAGHA, SHAHIN |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN |
|
18W | Application withdrawn |
Withdrawal date: 19930517 |
|
R18W | Application withdrawn (corrected) |
Effective date: 19930517 |