EP0063112A1 - Silicon carbide bodies - Google Patents

Silicon carbide bodies

Info

Publication number
EP0063112A1
EP0063112A1 EP80901959A EP80901959A EP0063112A1 EP 0063112 A1 EP0063112 A1 EP 0063112A1 EP 80901959 A EP80901959 A EP 80901959A EP 80901959 A EP80901959 A EP 80901959A EP 0063112 A1 EP0063112 A1 EP 0063112A1
Authority
EP
European Patent Office
Prior art keywords
silicon carbide
particles
self
silicon
mixture
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Withdrawn
Application number
EP80901959A
Other languages
German (de)
French (fr)
Inventor
Bernard North
Peter Kennedy
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
UK Atomic Energy Authority
Original Assignee
UK Atomic Energy Authority
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by UK Atomic Energy Authority filed Critical UK Atomic Energy Authority
Publication of EP0063112A1 publication Critical patent/EP0063112A1/en
Withdrawn legal-status Critical Current

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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
    • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/56—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
    • C04B35/565—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide
    • C04B35/573—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide obtained by reaction sintering or recrystallisation
    • 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
    • C01P2004/60—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
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/10—Solid density
    • 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
    • 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
    • C01P2006/80—Compositional purity

Definitions

  • This invention relates to silicon carbide bodies a in particular, to the production of bodies of self-bond silicon carbide by reaction sintering of a preformed mixture of particles of silicon carbide and carbon in the presence of molten silicon.
  • reaction sintering is hereinafter referred to as "siliconising” and one method of siliconising is described in UK patent Specification 1,180,918.
  • the present invention consists in a self-bonded silicon carbide body produced by siliconising a preformed mixture of particles of carbon and silicon carbide wherein the silicon carbide in the mixture is in the beta form and the silicon carbide in the body has a mean grain size in the range 0.1-5 microns.
  • Tb.e present invention also consists in a method of producing a self-bonded silicon carbide body by siliconising a preformed mixture of particles of carbon and silicon carbide in the beta form, the silicon carbide particles having a mean surface area in the range 0.5-20 square metres per gram, and in a self-bonded silicon carbide body so produced.
  • a self-bonded silicon carbide body in accordance with the invention when compared with a self-bonded silicon carbide body produced using particles of aloha silicon carbide has improved properties, in particular in the extent and nature of deformation and microcracking around indentations. For example in 500g load knoop indentation tests cracking was much more localised and damage far less extensive. Also there is a greater dependence of hardness on load and may be higher hardness at low loads. These results indicate that bodies in accordance with the invention will behave in general in a more plastic manner have less tendency to crack catastrophically and show greater wear resistance and surface toughness.
  • the coherent mixture of silicon carbide and carbon may be formed prior to siliconising by any convenient method such as extrusion, injection moulding, slipcasting or pressing.
  • the fine silicon carbide particles in beta form are preferably produced by passing silicon monoxide through a bed of particulate carbon which is converted to silicon carbide powder, the silicon monoxide vapour being generated by heating a mixture of silica and silicon separately from the bed of particulate carbon.
  • the silicon carbide powder had a surface area of 3.7 m 2 /g and the carbon powder consisted of crystallites which formed agglomerates with a surface area of about 6 m 2 /g.
  • the pellet was extruded through a profiled die to form components of uniform cross-section and the extrudate was cut and heated to 400°C to volatilise the binder.
  • Example 2 A mix containing carbon and beta-silicon carbide powders of the same size as in Example 1 but in the ratio 0.25:1 by weight, and sufficient polymeric binder to form a hard rigid body on compaction, was pressed isostatically at about 100 MN/m 2 to form a component which was subsequently 'green machined', using a diamond tool. The 'green' material was heated to 400°C to volatilise the binder an was then fired at 1650°C in the presence of molten silicon to convert it to a 90% dense silicon carbide containing free silicon.
  • Example 3 A mix containing carbon and beta-silicon carbide powders of the same size as in Example 1 but in the ratio 0.25:1 by weight, and sufficient polymeric binder to form a hard rigid body on compaction, was pressed isostatically at about 100 MN/m 2 to form a component which was subsequently 'green machined', using a diamond tool. The 'green' material was heated to 400°C to volatilise the bin
  • Beta silicon carbide powder surface area 2 m 2 /g, was mixed with carbon black, surface area 5 m /g, in the ratio 1:0.4 by weight.
  • An aqueous slip was made up and a slip-cast slab was made.
  • the slab was dried and siliconised at 1650oC for 2 hours in a vacuum of 1 torr. After cooling excess silicon was removed from the surface by abrasive blasting and the density of the slab was found to be 3.04g/cm 3 that is, it contained 19% by volume free silicon.
  • the mean grain size in the slab was approximately 0.7 micro
  • Example 4 Beta silicon carbide powder, surface area 4.4 m 2 /g vss mixed with carbon black, surface area 6 m 2 /g, in the ratio of 1:0.3.
  • a slab was formed as in Example 3 and siliconised at 1600oC for 30 minutes.
  • the density was 2.92 g/cm 3 (33% by volume free silicon) and the mean grain size was 0.5 microns.
  • Example 5 A beta silicon carbide powder, surface area 0.8 m 2 /g was mixed with graphite powder, surface area 60 m /g in the ratio 1:0.4 by weight. Binder and lubricants were mixed in and rods 4 mm in diameter were extruded. After removal of the binder the rods were siliconised at 1650°C for 2 hours in a vacuum of 1 torr. Density of the rod was 3.12 g/

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Ceramic Products (AREA)

Abstract

Corps en carbure de silicium auto-lies obtenus par silicisation d'un melange prepare a l'avance de particules de carbone et de carbure de silicium dans la forme beta, presentant une grosseur de grains moyenne comprise dans la gamme 0,1-5 microns. Un tel corps en carbure de silicium peut etre produit en utilisant des particules de carbure de silicium possedant une surface specifique comprise dans la gamme 0,5- 20 metres carres par gramme. Les particules de carbure de silicium peuvent etre produites en chauffant un melange de silice et de silicium pour produire des vapeurs de monoxyde de silicium et en faisant passer les vapeurs au travers d'un lit de carbone particulaire.Self-bonded silicon carbide body obtained by siliciding a mixture prepared in advance of carbon particles and silicon carbide in the beta form, having an average grain size in the range 0.1-5 microns . Such a silicon carbide body can be produced using silicon carbide particles having a specific surface in the range 0.5-20 square meters per gram. The silicon carbide particles can be produced by heating a mixture of silica and silicon to produce vapors of silicon monoxide and passing the vapors through a bed of particulate carbon.

Description

Silicon Carbide Bodies.
This invention relates to silicon carbide bodies a in particular, to the production of bodies of self-bond silicon carbide by reaction sintering of a preformed mixture of particles of silicon carbide and carbon in the presence of molten silicon. Such reaction sintering is hereinafter referred to as "siliconising" and one method of siliconising is described in UK patent Specification 1,180,918.
The present invention consists in a self-bonded silicon carbide body produced by siliconising a preformed mixture of particles of carbon and silicon carbide wherein the silicon carbide in the mixture is in the beta form and the silicon carbide in the body has a mean grain size in the range 0.1-5 microns. Tb.e present invention also consists in a method of producing a self-bonded silicon carbide body by siliconising a preformed mixture of particles of carbon and silicon carbide in the beta form, the silicon carbide particles having a mean surface area in the range 0.5-20 square metres per gram, and in a self-bonded silicon carbide body so produced.
A self-bonded silicon carbide body in accordance with the invention, when compared with a self-bonded silicon carbide body produced using particles of aloha silicon carbide has improved properties, in particular in the extent and nature of deformation and microcracking around indentations. For example in 500g load knoop indentation tests cracking was much more localised and damage far less extensive. Also there is a greater dependence of hardness on load and may be higher hardness at low loads. These results indicate that bodies in accordance with the invention will behave in general in a more plastic manner have less tendency to crack catastrophically and show greater wear resistance and surface toughness.
The coherent mixture of silicon carbide and carbon may be formed prior to siliconising by any convenient method such as extrusion, injection moulding, slipcasting or pressing.
The fine silicon carbide particles in beta form are preferably produced by passing silicon monoxide through a bed of particulate carbon which is converted to silicon carbide powder, the silicon monoxide vapour being generated by heating a mixture of silica and silicon separately from the bed of particulate carbon.
The following are examples of ways of carrying the invention into effect. Example 1.
A mix containing carbon and beta-silicon carbide powders in the ratio 0.5:1 by weight, and sufficient polymeric binder to provide 42% porosity in the fully-consolidated body on removal of the binder, was formed into a cylincrical pellet by pressing at about 50 MN/rn with the exclusion of air. The silicon carbide powder had a surface area of 3.7 m2/g and the carbon powder consisted of crystallites which formed agglomerates with a surface area of about 6 m2/g. The pellet was extruded through a profiled die to form components of uniform cross-section and the extrudate was cut and heated to 400°C to volatilise the binder. The 'green' material was then fired at 1550ºC in the presence of molten silicon to convert it to a 90% dense silicon carbide containing 10% free silicon. Example 2 A mix containing carbon and beta-silicon carbide powders of the same size as in Example 1 but in the ratio 0.25:1 by weight, and sufficient polymeric binder to form a hard rigid body on compaction, was pressed isostatically at about 100 MN/m2 to form a component which was subsequently 'green machined', using a diamond tool. The 'green' material was heated to 400°C to volatilise the binder an was then fired at 1650°C in the presence of molten silicon to convert it to a 90% dense silicon carbide containing free silicon. Example 3
Beta silicon carbide powder, surface area 2 m 2/g, was mixed with carbon black, surface area 5 m /g, in the ratio 1:0.4 by weight. An aqueous slip was made up and a slip-cast slab was made. The slab was dried and siliconised at 1650ºC for 2 hours in a vacuum of 1 torr. After cooling excess silicon was removed from the surface by abrasive blasting and the density of the slab was found to be 3.04g/cm3 that is, it contained 19% by volume free silicon. The mean grain size in the slab was approximately 0.7 micro
Example 4 Beta silicon carbide powder, surface area 4.4 m2/g vss mixed with carbon black, surface area 6 m2/g, in the ratio of 1:0.3.
A slab was formed as in Example 3 and siliconised at 1600ºC for 30 minutes. The density was 2.92 g/cm3 (33% by volume free silicon) and the mean grain size was 0.5 microns.
Example 5 A beta silicon carbide powder, surface area 0.8 m2/g was mixed with graphite powder, surface area 60 m /g in the ratio 1:0.4 by weight. Binder and lubricants were mixed in and rods 4 mm in diameter were extruded. After removal of the binder the rods were siliconised at 1650°C for 2 hours in a vacuum of 1 torr. Density of the rod was 3.12 g/
(10% by volume free silicon) the meangrain size was about
5 microns and the Knoop hardness at 50g load was 3,650 hg/mm2

Claims

1. A self-bonded silicon carbide body produced by siliconising a preformed mixture of particles of carbon and silicon carbide wherein the silicon carbide in the preforme mixture is in the beta form and the silicon carbide in the self-bonded silicon carbide body has a mean grain size in the range 0.1-5 microns.
2. A method of producing a self-bonded silicon carbide body by siliconising a preformed mixture of particles of carbon and silicon carbide in the beta form, the silicon carbide particles having a mean surface area in the range of 0.5-20 square metres per gram,
3. A method of producing a self-bonded silicon carbide body as claimed in claim 2 wherein the silicon carbide particles have a mean surface area less than 5 square. metres per gram.
4. A method of producing a self-bonded silicon carbide body as claimed in claim 2 or claim 3 wherein the silicon carbide particles in the mixture are produced by passing through a bed of particulate carbon silicon monoxide vapour generated separately by heating a mixture of silicon and silica.
EP80901959A 1980-10-27 1980-10-27 Silicon carbide bodies Withdrawn EP0063112A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/GB1980/000182 WO1982001545A1 (en) 1980-10-27 1980-10-27 Silicon carbide bodies

Publications (1)

Publication Number Publication Date
EP0063112A1 true EP0063112A1 (en) 1982-10-27

Family

ID=10510428

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80901959A Withdrawn EP0063112A1 (en) 1980-10-27 1980-10-27 Silicon carbide bodies

Country Status (4)

Country Link
EP (1) EP0063112A1 (en)
JP (1) JPS57501578A (en)
DE (1) DE3050618A1 (en)
WO (1) WO1982001545A1 (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4513030A (en) * 1982-06-18 1985-04-23 The United States Of America As Represented By The United States Department Of Energy Method of producing silicon carbide articles
JPH09235161A (en) * 1996-03-01 1997-09-09 Ngk Insulators Ltd Sintered si-sic material having excellent corrosion resistance, furnace tool and furnace lining material made thereof and furnace produced by using the material
US6609452B1 (en) 2000-01-11 2003-08-26 M Cubed Technologies, Inc. Silicon carbide armor bodies, and methods for making same
US7104177B1 (en) 2000-01-11 2006-09-12 Aghajanian Michael K Ceramic-rich composite armor, and methods for making same
DE102006055469A1 (en) 2006-11-23 2008-05-29 Universität Paderborn A method of making an article at least partially with silicon carbide fill from a blank of carbonaceous material
WO2009140791A1 (en) * 2008-05-21 2009-11-26 Dalian Institute Of Chemical Physics, Chinese Academy Of Sciences Process for producing silicon carbide

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1180918A (en) * 1966-06-10 1970-02-11 Atomic Energy Authority Uk Improvements in or relating to the Manufacture of Dense Bodies of Silicon Carbide.
GB1478898A (en) * 1973-10-24 1977-07-06 Gen Electric Silicon carbide ceramic
JPS5924754B2 (en) * 1977-07-07 1984-06-12 信越化学工業株式会社 Method for manufacturing silicon carbide molded body
JPS54122312A (en) * 1978-03-15 1979-09-21 Hiroshige Suzuki Silicon carbide powder for sintering use and preparation thereof
US4166841A (en) * 1978-05-03 1979-09-04 Ford Motor Company Method for making pure beta silicon carbide
US4195049A (en) * 1978-07-13 1980-03-25 Ford Motor Company Method of increasing the strength of a beta silicon carbide article

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8201545A1 *

Also Published As

Publication number Publication date
WO1982001545A1 (en) 1982-05-13
JPS57501578A (en) 1982-09-02
DE3050618A1 (en) 1982-11-18

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