DE2356921C2 - Process for the production of silicon nitride bodies by reaction sintering of silicon powder in a nitrogen atmosphere and subsequent pressure sintering - Google Patents
Process for the production of silicon nitride bodies by reaction sintering of silicon powder in a nitrogen atmosphere and subsequent pressure sinteringInfo
- Publication number
- DE2356921C2 DE2356921C2 DE2356921A DE2356921A DE2356921C2 DE 2356921 C2 DE2356921 C2 DE 2356921C2 DE 2356921 A DE2356921 A DE 2356921A DE 2356921 A DE2356921 A DE 2356921A DE 2356921 C2 DE2356921 C2 DE 2356921C2
- Authority
- DE
- Germany
- Prior art keywords
- silicon
- sintering
- reaction
- silicon nitride
- production
- 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.)
- Expired
Links
Classifications
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- 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
- C04B35/584—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 silicon nitride
- C04B35/593—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 silicon nitride obtained by pressure sintering
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- 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
- C04B35/71—Ceramic products containing macroscopic reinforcing agents
- C04B35/74—Ceramic products containing macroscopic reinforcing agents containing shaped metallic materials
- C04B35/76—Fibres, filaments, whiskers, platelets, or the like
-
- 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
- C04B35/71—Ceramic products containing macroscopic reinforcing agents
- C04B35/78—Ceramic products containing macroscopic reinforcing agents containing non-metallic materials
- C04B35/80—Fibres, filaments, whiskers, platelets, or the like
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Ceramic Products (AREA)
Description
Es ist bekannt (DE-AS 16 46 700), Siliciumnitrid-Keramikkörper herzustellen, indem zuerst Siliciumnitrid hergestellt, dieses dann gebrochen und gemahlen und pulverförmiges Siliciumnitrid unter Druck in Gegenwart eines B2O3- oder Phosphat-Bindemittels gesintert wird. Alle diese Verfahren sind sehr aufwendig und die erhaltenen Keramikkörper nicht sehr dicht. Im Stand der Technik der DE-AS 16 46 700 ist das Reaktionssintern von Siliciumpulver allein oder mit feuerfesten Zusätzen in Stickstoffatmosphäre unter Bildung von Siliciumnitrid-Körpern erwähnt. Die DE-OS 21 34 072 betrifft die Herstellung von Siliciumnitrid-Gegenständen durch Reaktionssintern eines Preßlings aus Silicium, enthaltend ein Flußmittel, in nitrierender Atmosphäre und anschließendes Heißpressen des reaktionsgesinterten Körpers. Nachteilig bei diesem Verfahren ist, daß der reaktionsgesinterte Körper noch eine beträchtliche Porosität aufweist und daher bei dem sich anschließenden Heißpressen zur Eliminierung dieser Porosität und Erreichung einer optimalen Dichte des Bauteils praktisch die gleichen Schwierigkeiten auftreten wie beim Heißpressen von aus Siliciumnitrid geformten Rohlingen.It is known (DE-AS 16 46 700) to produce silicon nitride ceramic bodies by first producing silicon nitride, which is then broken and ground and powdered silicon nitride is sintered under pressure in the presence of a B 2 O 3 or phosphate binder. All of these processes are very complex and the ceramic bodies obtained are not very dense. In the prior art of DE-AS 16 46 700, the reaction sintering of silicon powder alone or with refractory additives in a nitrogen atmosphere with the formation of silicon nitride bodies is mentioned. DE-OS 21 34 072 relates to the production of silicon nitride objects by reaction sintering a compact made of silicon containing a flux in a nitriding atmosphere and subsequent hot pressing of the reaction sintered body. The disadvantage of this method is that the reaction-sintered body still has considerable porosity and therefore practically the same difficulties arise in the subsequent hot pressing to eliminate this porosity and achieve an optimal density of the component as in the hot pressing of blanks formed from silicon nitride.
Aufgabe der Erfindung ist die Verringerung der Kosten zur Herstellung von Siliciumnitrid-Formkörpern praktisch theoretischer Dichte gegenüber dem Heißpressen von Siliciumnitrid-Pulvern, sowie die *5 Verringerung der Porosität und Erleichterung des Heißpressens der reaktionsgesinterten Gegenstände gegenüber den bekannten Verfahren zum Reaktionssintern von Silicium und anschließendem Heißpressen des reaktionsgesinterten Siliciumnitrid-Körpers. soThe object of the invention is to reduce the costs of producing silicon nitride molded bodies practically theoretical density compared to hot pressing of silicon nitride powders, as well as the * 5 Reducing the porosity and facilitating hot pressing of the reaction sintered articles compared to the known process for the reaction sintering of silicon and subsequent hot pressing of the reaction sintered silicon nitride body. so
Ausgehend von dem oben genannten Stand der Technik wird diese Aufgabe dadurch gelöst, daß man den Preßling zwischen dem Reaktionssintern und Diurksintern mit einem Flußmittel infiltriert. Das Flußmittel ist vorzugsweise Magnesiumoxid in einer Menge von I bis 5 Vol.-%.Based on the above-mentioned prior art, this object is achieved in that one infiltrated the compact with a flux between the reaction sintering and diurksintering. That Flux is preferably magnesium oxide in an amount of 1 to 5% by volume.
Die vollständige Umwandlung des Siliciumpulver-Formlings zu einem ineinander greifenden Kristallaggregat von Siliciumnitrid erreicht man in Stickstockatmosphäre bei einer Temperatur unmittelbar unter dem Schmelzpunkt von Silicium. Dies dauert im allgemeinen etwa 12 h, abhängig von der Querschnittsfläche des Preßlings. Die Reaktion setzt bei 1200°C ein, ist jedoch schneller bei Temperaturen in der Nähe von 1400°C. Da die Reaktion exotherm ist, ist es insbesondere bei großen Querschnittsflächen vorzuziehen, nicht über 13500C zu gehen, um ein örtliches Schmelzen von Sjliciumpulvern zu Klumpen, die einem Reaktionssintern unzugänglich wären, zu verhindern. Die Nitridbildung kann vorzugsweise auch 2stufig ausgeführt werden (GB-PS 8 87 942). Obwohl keine Dimensionsänderungen oder merkliche Verziehungen während des Reaktionssinterns stattfinden, ist es notwendig, ausreichenden Materialüberschuß vorzusehen, um das Schrumpfen während des folgenden Drucksinterns zu kompensieren. Es kann auch notwendig sein, Überschußmateria! an bestimmten Flächen vorzusehen, die letztlich abgearbeitet werden, damit der erhaltene Formkörper hohe Oberflächengüte aufweistThe complete conversion of the silicon powder molding to an interlocking crystal aggregate of silicon nitride is achieved in a stick-stick atmosphere at a temperature just below the melting point of silicon. This generally takes about 12 hours, depending on the cross-sectional area of the compact. The reaction starts at 1200 ° C, but is faster at temperatures near 1400 ° C. Since the reaction is exothermic, it is preferable, especially for large cross-sectional areas not to go more than 1,350 0 C to localized melting of Sjliciumpulvern to lumps that were inaccessible to reaction sintering to prevent. The nitride formation can preferably also be carried out in two stages (GB-PS 8 87 942). Although no dimensional changes or noticeable distortions take place during the reaction sintering, it is necessary to provide sufficient excess material to compensate for the shrinkage during the subsequent pressure sintering. It may also be necessary to remove excess material! to be provided on certain surfaces that are ultimately processed so that the molded body obtained has a high surface quality
Der Siliciumnitrid-Körper wird dazu in einer Graphitform, überzogen mit einer Bornitrid-Anstrichmasse, unter leichtem Druck verdichtet, während die Temperatur auf maximal 16000C bis 18500C gesteigert und gleichzeitig der Preßdruck auf 1035 N/cm2 erhöht wird. Diese Bedingungen werden dann kurze Zeit, unabhängig von der Materialstärke, in der Form aufrechterhalten und dann langsam aufgehoben. Es schließt sich nun ein Tempern zur Aufhebung der Restspannung an. Durch Verdichten des Siüciumpulvers zu einem Körper in etwa Endform und durch Anwendung von Graphitformen und möglicherweise einer einfachen Schmiedeoperatron ist es möglich, Formkörper weitestgehend der Endform herzustellen, so daß die aufwendigen Nacharbeitskosten minimal gehalten werden.The silicon body is to in a graphite mold, coated with a boron nitride paint composition, compacted under gentle pressure while the temperature to a maximum of 1600 0 C increased to 1850 0 C and at the same time the pressing pressure 1035 N / cm 2 is increased. These conditions are then maintained in the mold for a short time, regardless of the material thickness, and then slowly removed. This is now followed by tempering to remove the residual stress. By compacting the Siüciumpulver into a body in an approximately final shape and by using graphite molds and possibly a simple forging operator, it is possible to produce shaped bodies largely in the final shape, so that the costly reworking costs are kept to a minimum.
Dieses Verfahren wird erfindungsgemäß vereinfacht durch Infiltrieren eines Flußmittels in den porösen Sinterkörper vor der Stufe des Drucksintern. Als Flußmittel eignen sich Magnesiumoxid, Magnesiumnitrid, Calciumoxid, Aluminiumoxid, Eisenoxid, Berylliumoxid, Berylliumnitrid und Calciumnitrid.According to the invention, this process is simplified by infiltrating a flux into the porous Sintered body before the step of pressure sintering. Magnesium oxide, magnesium nitride, Calcium oxide, aluminum oxide, iron oxide, beryllium oxide, beryllium nitride and calcium nitride.
Zur Herstellung von Gegenständen mit einer ungewöhnlichen Kombination von physikalischen und mechanischen Eigenschaften, insbesondere für Teile für tribologische und Hochtemperatur-Systeme werden dem Siliciumpulver vor dem Reaktionssintern weitere Stoffe zugesetztFor making items with an unusual combination of physical and mechanical properties, especially for parts for tribological and high temperature systems further substances were added to the silicon powder before the reaction sintering
Beispiele für diese Materialien sind Dispersionen von 1 bis 50 Vol.-% Siliciumdioxid, Siliciumcarbid, Graphit, Bornitrid, Aluminium, Titan oder Eisen in feinteiliger oder grobkörniger Form in regelloser Anordnung oder als orientierte Drähte oder Fasern oder aber auch in Sandwichstruktur.Examples of these materials are dispersions of 1 to 50% by volume silicon dioxide, silicon carbide, graphite, Boron nitride, aluminum, titanium or iron in finely divided or coarse-grained form in a random arrangement or as oriented wires or fibers or in a sandwich structure.
Durch selektive Anordnung von Verstärkungsmaterialien während der Anfangsstufen der Herstellung ist es möglich, Teile mit lokal besseren Eigenschaften, wie Oberflächenhärte, elektrische Leitfähigkeit, thermisches Isolationsvermögen, herzustellen oder mit speziellen Eigenschaften hinsichtlich der Verbindung von Keramik und Metall. Fs ist auch möglich, die Struktur dieser Produkte zu modifizieren und die Eigenschaften durch weitere Warmbearbeitung zu beeinflussen, welche auch darauf gerichtet sein kann, um aus dem Rohkörper besondere Formen herzustellen.It is through selective placement of reinforcement materials during the initial stages of manufacture possible parts with locally better properties, such as surface hardness, electrical conductivity, thermal Insulation capacity, to be produced or with special properties with regard to the connection of ceramics and metal. Fs is also possible to modify the structure of these products and the properties through to influence further hot working, which can also be aimed at getting out of the raw body to produce special shapes.
Auf speziellen Wunsch eines Abnehmers wurden Körper mit praktisch theoretischer Dichte aus Siliciumnitrid, enthaltend 1 bis 5Vol.-% Magnesiumoxid, hergestellt mit zusätzlich 10 bis 30 Vol.-% Siliciumcarbid für besondere tribologische Hochtemperatur-Eigenschaften, mit IO bis 30 Vol.-% Graphit für Lagereigenschaften, mit 10 bis 30% Bornitrid für tribologische und Verschleiß-Eigenschaften und schließlich 10 bis 30% Eisen für Schlagfestigkeit und Eigenschaften bei Raumtemperatur.At the special request of a customer, bodies with a practically theoretical density were made of silicon nitride, Containing 1 to 5% by volume of magnesium oxide, produced with an additional 10 to 30% by volume of silicon carbide for special tribological high-temperature properties, with IO up to 30 vol .-% graphite for storage properties, with 10 to 30% boron nitride for tribological and wear properties and finally 10 to 30% Iron for impact resistance and room temperature properties.
Claims (2)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB5244572A GB1393579A (en) | 1972-11-14 | 1972-11-14 | Method of producing high density silicon nitride |
Publications (2)
Publication Number | Publication Date |
---|---|
DE2356921A1 DE2356921A1 (en) | 1974-05-30 |
DE2356921C2 true DE2356921C2 (en) | 1982-09-23 |
Family
ID=10463949
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
DE2356921A Expired DE2356921C2 (en) | 1972-11-14 | 1973-11-14 | Process for the production of silicon nitride bodies by reaction sintering of silicon powder in a nitrogen atmosphere and subsequent pressure sintering |
Country Status (2)
Country | Link |
---|---|
DE (1) | DE2356921C2 (en) |
GB (1) | GB1393579A (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
IT1117334B (en) * | 1977-12-23 | 1986-02-17 | Fiat Spa | PROCEDURE FOR THE SYNTERIZATION OF SILICON NITRIDE REACTION BONDED |
JPS6022676B2 (en) * | 1980-02-23 | 1985-06-03 | 日本鋼管株式会社 | Silicon nitride/boron nitride composite sintered body and its manufacturing method |
US4388255A (en) * | 1981-03-27 | 1983-06-14 | Boeing Aerospace Co. (A Division Of The Boeing Company) | Method for producing pre-shaped α-silicon nitride whisker compacts and loose whiskers for composite material reinforcement |
EP0120849B1 (en) * | 1982-09-30 | 1987-05-27 | Ford Motor Company | Method of making high strength hot pressed silicon nitride |
DE3278499D1 (en) * | 1982-09-30 | 1988-06-23 | Ford Motor Co | Process for producing cutting tools from si3n4-silicon nitride by chemical bonding or by hot-pressing |
US4579699A (en) * | 1983-09-29 | 1986-04-01 | The Boeing Company | Method for making α-Si3 N4 whiskers and articles therefrom |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1069108A (en) * | 1965-04-22 | 1967-05-17 | Montedison Spa | A process for preparing silicon nitride articles |
GB1340696A (en) * | 1970-07-10 | 1973-12-12 | Lucas Industries Ltd | Method of manufacturing silicon nitride products |
-
1972
- 1972-11-14 GB GB5244572A patent/GB1393579A/en not_active Expired
-
1973
- 1973-11-14 DE DE2356921A patent/DE2356921C2/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
DE2356921A1 (en) | 1974-05-30 |
GB1393579A (en) | 1975-05-07 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
OD | Request for examination | ||
D2 | Grant after examination | ||
8339 | Ceased/non-payment of the annual fee |