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EP0569391A1 - Procede de fabrication d'un corps ceramique a base de nitrure de bore - Google Patents

Procede de fabrication d'un corps ceramique a base de nitrure de bore

Info

Publication number
EP0569391A1
EP0569391A1 EP19920902758 EP92902758A EP0569391A1 EP 0569391 A1 EP0569391 A1 EP 0569391A1 EP 19920902758 EP19920902758 EP 19920902758 EP 92902758 A EP92902758 A EP 92902758A EP 0569391 A1 EP0569391 A1 EP 0569391A1
Authority
EP
European Patent Office
Prior art keywords
boron nitride
ceramic powder
powder
capsule
based ceramic
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Withdrawn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
EP19920902758
Other languages
German (de)
English (en)
Inventor
Pär-Anders SUNNERKRANTZ
Roger West
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.)
Metso Powdermet AB
Original Assignee
ABB Powdermet AB
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 ABB Powdermet AB filed Critical ABB Powdermet AB
Publication of EP0569391A1 publication Critical patent/EP0569391A1/fr
Withdrawn legal-status Critical Current

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
    • C04B35/515—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
    • C04B35/58—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 borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
    • C04B35/583—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 borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on boron nitride

Definitions

  • the invention relates to a method of manufacturing an essentially dense ceramic body, starting from a boron nitride-based ceramic powder, by hot pressing.
  • the body shall be easily mechanically machined and removable from, for example, a steel body by blasting.
  • the boron nitride- 10 based ceramic body is primarily used for forming of powder- metallurgically manufactured metallic bodies, for example as a core or mould in hot-isostatic pressing.
  • Ceramic bodies with essentially full theoretical density, are suitable to use for forming in connection with the manufacture of products from metal powder by hot-isostatic pressing.
  • Material such as aluminium oxide or zirconium
  • 25 materials are then graphite and boron nitride, preferably in the form of hexagonal boron nitride.
  • Graphite can only be used where carbonizing through diffusion and dissolution, at normal temperatures for hot-isostatic pressing, does not take place to any harmful extent and does not constitute a 0 problem, such as, for example, in the case of cobalt-base alloys. From this follows that boron nitride at present constitutes the preferred material. It is, of course, possible to use graphite if it is coated with a diffusion- inhibiting layer, for example of boron nitride.
  • German Patent DE-A-4 003 809 it is known, starting from a boron nitride power containing up to 4 per cent by weight boron oxide, to add up to 3 % A1N, up to 1 % Ca and up to 50 % of additives such as Zr ⁇ 2 , Si 3 N4, SiC, B 4 C,. Si ⁇ 2 , AI 2 O 3 , Y 2 O 3 , MgO or metals to optimize the technical properties.
  • the powder is preformed and pre-compressed by cold-isostatic pressing, possibly with the addition of 0.5-6 % of a binder, into a porous body with a density of at least 50 % of the theoretical density, in the following designated %TD.
  • the preformed body is placed in a steel capsule and heated to between 500 and 1100°C, whereupon the binder is driven off. Thereafter, the capsule is evacuated and sealed gas-tightly ' to be finally compacted and consolidated by hot-isostatic pressing in the conventional manner at a temperature of between 1200 and 1500°C and a pressure of between 50 and 300 MPa.
  • the present invention relates Lo a method of manufacturing an essentially dense and mechanically machinable ceramic body, starting from a boron nitride powder, without pre- compaction or preforming, the powder being compacted and consolidated by means of hot pressing.
  • hot pressing is meant in the following uniaxial pressing in a heated tool, uniaxial pressing of hot powder, hot- isostatic pressing as well as hot pressing using pseudo- isostatic methods.
  • Boron nitride powder in commercially available qualities usually contains boron oxide in contents of up to 2 per cent by weight.
  • the boron oxide is a glass-forming material which acts as a sintering aid in connection with compaction and consolidation of boron nitride.
  • the invention is also applicable to the manufacture of boron nitride-based ceramic bodies to which additives such as Zr ⁇ 2 , Si 3 N 4 , SiC, B 4 C, Si ⁇ 2 , AI 2 O 3 , Y 2 O 3 , MgO, mixtures of these ceramic materials, or metals are made to optimize the technical properties.
  • the content of sintering aid Prior to compaction and consolidation of the boron nitride- based ceramic powder mentioned, the content of sintering aid is corrected to a content of between 3 and 10 per cent by weight.
  • the sintering aid substantially consists of a glass-forming material, i.e. a material which, per se or together with the boron oxide present in the boron nitride powder, while being heated to the pressing temperature, is transformed into a glass.
  • the glass forms a compact binder phase which essentially fills up the remaining spaces between the compressed grains in the ceramic powder and binds the grains into a dense and mechanically machinable ceramic body.
  • the boron nitride-based ceramic powder with additives is compacted and consolidated by means of hot pressing into an essentially dense wuy, ⁇ re_era_/_y into a jjo witr_ a density exceeding 90 %TD, at a temperature of between 500 and 1500°C and a pressure of between 50 and 300 MPa.
  • the content of sintering aid in the boron oxide-containing boron nitride-based ceramic powder is corrected, where necessary, to the intended content according to the invention in any of the following ways:
  • boron oxide powder or another powdered material which, per se or together with the boron oxide present in the boron nitride, while being heated forms a glass.
  • Suitable materials in addition to boron oxide and boron oxide-based glass, are other glass powders, ceramic clays or silicate minerals which together with the existing boron oxide form a glass with a suitable viscosity at the pressing temperature.
  • the mixing is advantageously performed by means of co-grinding, thus obtaining a suitable distribution of the sintering aid, evenly distributed over the surface of the boron nitride grains.
  • co-grinding with boron oxide present in the powder provides a local liquid phase reaction, as a consequence of the temperature increase during the grinding, whereby the glass-forming sintering- promoting additive is at least partially dissolved in the boron oxide;
  • a powder suspension containing the sintering- promoting, glass-forming material for example a boron oxide powder, a boron oxide-based glass powder, another glass powder or another glass-forming material such as amorphous silica.
  • the powder is suspended in a liquid, such as water, ethanol, methanol or another alcohol which is driven off after being mixed in;
  • the oxide content, especially the boron oxide content in the boron nitride-containing cermic powder may be increased by measures such as:
  • oxides or other oxygen-containing compounds which during the process, grinding, heating, pressing, react with the boron nitride while forming boron oxide .
  • the glass- forming materials form a compact binder phase which essentially fills up the spaces between the grains and cements them together into a dense and mechanically machinable ceramic body which is essentially free from pores and microcracks.
  • the boron nitride-based powder is suitably granulated in connection with the content of sintering- promoting, glass-forming agent being corrected.
  • the content of sintering aid is preferably corrected by correcting the boron oxide content in the boron nitride- based ceramic powder in any of the ways described above into a boron oxide content of between 4.5 and 7 per cent by weight.
  • the content of sintering aid is corrected to a content of between 3 and 10 per cent by weight before the powder is filled into a steel capsule.
  • the ceramic powder is packed into a fill density corresponding to 15 to 60 %TD.
  • After filling of the steel capsule it is evacuated and sealed essentially gas-tightly before the capsule and the ceramic powder contained in the capsule is compacted and sintered by hot- isostatic pressing at a temperature of between 500 and 1500°C and a pressure of 50 to 300 MPa. A ceramic body with a density of at least 90 %TD is then formed.
  • the powder is filled into a capsule which, according to one embodiment of the invention, is joined together and designed to be deformed symmetri ⁇ cally, hence taking up the heavy deformations of the capsule which arise during the compaction of a powdered material with low fill density into an essentially dense body.
  • This symmetrical deformation is achieved in one embodiment by designing and joining together the capsule such that, at a critical value of the applied external overpressure, an instability arises in the capsule, the sheet is corrugated and the capsule deformed symmetrically and regularly, the great reduction in volume in connection with the compaction of the powder from a low fill density to an essentially dense body then being taken up by the capsule without leakage arising.
  • the deformation is control ⁇ led by stiffening certain sheets such that other sheets are stretched during the compression.
  • this symmetrical deformation of the capsule is achieved by joining together the sheets included in the steel capsule by means of joints with a high folded- up flange.
  • joints with a high flange they are able to absorb the ⁇ svy deformation of the c sule which results from the great compression of the ceramic powder from a low fill density into an essentially dense body, without leakage arising.
  • a granulated boron nitride-based ceramic powder in which the boron oxide content has been corrected to a content of between 4.5 and 7 per cent by weight, is filled into a steel capsule.
  • the steel capsule is designed and joined together according to any of the methods described in the foregoing, to take up the great deformations during the compaction.
  • granulated ceramic powder is packed into a fill density corresponding to 20 to 60 %TD.
  • the steel capsule After the steel capsule has been filled, it is evacuated and sealed essen ⁇ tially gas-tightly before the capsule and the ceramic powder enclosed in the capsule are compacted and sintered by hot- isostatic pressing at a temperature of between 1000 and 1250°C and a pressure of 100 to 140 MPa. This leads to the formation of a ceramic body with a density of at least 96 %TD.
  • Boron nitride-based ceramic bodies bonded and manufactured according to the invention are essentially dense, while at the same time being easily mechanically machinable. This renders them most suitable for use as shape-imparting cores or moulds during powdermetallurgical manufacture of com ⁇ ponents from metal powder. After forming, they are then easily mechanically removed, for example by blasting. To further improve the possibilities of machining of the cera ⁇ mic bodies, by making possible machining by electroerosive methods, so-called spark machining, 5 to 10 per cent by weight carbon is added to the ceramic powder in a special embodiment.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Ceramic Products (AREA)
  • Powder Metallurgy (AREA)

Abstract

Procédé de fabrication par estampage à chaud d'un corps céramique dense et usinable par voie mécanique, à partir d'une poudre céramique à base de nitrure de bore contenant également un produit d'aide au frittage sous forme d'oxyde de bore. Le produit d'aide au frittage, de préférence sous forme d'un matériau pouvant, en soi ou associé à de l'oxyde de bore déjà existant, former du verre, constitue de 3 à 10 % en poids. On rend compacte et solide la poudre céramique à une température comprise entre 500 et 1500 °C et à une pression comprise entre 50 et 300 MPa, afin d'obtenir un corps dont la densité équivaut à environ 90 % de la densité théorique.
EP19920902758 1991-01-09 1991-12-23 Procede de fabrication d'un corps ceramique a base de nitrure de bore Withdrawn EP0569391A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9100054A SE468558B (sv) 1991-01-09 1991-01-09 Saett att framstaella en keramisk kropp innehaallande bornitrid
SE9100054 1991-01-09

Publications (1)

Publication Number Publication Date
EP0569391A1 true EP0569391A1 (fr) 1993-11-18

Family

ID=20381561

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19920902758 Withdrawn EP0569391A1 (fr) 1991-01-09 1991-12-23 Procede de fabrication d'un corps ceramique a base de nitrure de bore

Country Status (3)

Country Link
EP (1) EP0569391A1 (fr)
SE (1) SE468558B (fr)
WO (1) WO1992012107A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI276618B (en) * 2003-09-25 2007-03-21 Sumitomo Metal Ind Machinable ceramic
CN107226700A (zh) * 2017-06-09 2017-10-03 哈尔滨工业大学 一种Si3N4‑BN‑MAS陶瓷复合材料及其制备方法
CN109761619A (zh) * 2019-03-11 2019-05-17 武汉理工大学 一种氮化硼陶瓷及其制备方法和制备设备

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR0134026B1 (ko) * 1988-11-10 1998-04-18 후까가와 신이찌 내용손성이 우수한 bn계 세라믹스
CH677488A5 (fr) * 1989-02-14 1991-05-31 Htm Ag

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9212107A1 *

Also Published As

Publication number Publication date
SE9100054D0 (sv) 1991-01-09
SE468558B (sv) 1993-02-08
SE9100054L (sv) 1992-07-10
WO1992012107A1 (fr) 1992-07-23

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