EP0213113A1 - Method of producing sintered bodies from an aluminium sinter mixture - Google Patents
Method of producing sintered bodies from an aluminium sinter mixture Download PDFInfo
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- EP0213113A1 EP0213113A1 EP86890217A EP86890217A EP0213113A1 EP 0213113 A1 EP0213113 A1 EP 0213113A1 EP 86890217 A EP86890217 A EP 86890217A EP 86890217 A EP86890217 A EP 86890217A EP 0213113 A1 EP0213113 A1 EP 0213113A1
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- Prior art keywords
- aluminum
- sintered
- wear
- mixture
- aluminium
- Prior art date
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- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 49
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 44
- 239000000203 mixture Substances 0.000 title claims abstract description 24
- 238000000034 method Methods 0.000 title claims description 10
- 239000004411 aluminium Substances 0.000 title abstract 4
- 239000000654 additive Substances 0.000 claims abstract description 19
- 230000000996 additive effect Effects 0.000 claims abstract description 11
- 239000013078 crystal Substances 0.000 claims abstract description 8
- 150000004760 silicates Chemical class 0.000 claims abstract description 7
- 150000001247 metal acetylides Chemical class 0.000 claims abstract description 5
- 150000004767 nitrides Chemical class 0.000 claims abstract description 5
- 238000005245 sintering Methods 0.000 claims description 27
- 239000002245 particle Substances 0.000 claims description 20
- 239000011159 matrix material Substances 0.000 claims description 12
- 238000002844 melting Methods 0.000 claims description 8
- 230000008018 melting Effects 0.000 claims description 8
- -1 aluminum compound Chemical class 0.000 claims description 5
- 239000000843 powder Substances 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 230000008569 process Effects 0.000 claims description 2
- 230000001681 protective effect Effects 0.000 claims description 2
- 150000001399 aluminium compounds Chemical class 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 8
- 238000000465 moulding Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 238000003825 pressing Methods 0.000 description 6
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 4
- 239000012790 adhesive layer Substances 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 4
- 230000006872 improvement Effects 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 2
- 230000008961 swelling Effects 0.000 description 2
- 229910020711 Co—Si Inorganic materials 0.000 description 1
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 238000005234 chemical deposition Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000005501 phase interface Effects 0.000 description 1
- 238000000053 physical method Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- MTPVUVINMAGMJL-UHFFFAOYSA-N trimethyl(1,1,2,2,2-pentafluoroethyl)silane Chemical compound C[Si](C)(C)C(F)(F)C(F)(F)F MTPVUVINMAGMJL-UHFFFAOYSA-N 0.000 description 1
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/05—Mixtures of metal powder with non-metallic powder
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
- C22C32/001—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides
- C22C32/0015—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides with only single oxides as main non-metallic constituents
- C22C32/0036—Matrix based on Al, Mg, Be or alloys thereof
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
- C22C32/0047—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
- C22C32/0089—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with other, not previously mentioned inorganic compounds as the main non-metallic constituent, e.g. sulfides, glass
Definitions
- the invention relates to a process for producing sintered shaped bodies from an aluminum sintered mixture with an addition of wear-resistant powder particles, the sintered mixture being pressed to form a shaped body, heated to a sintering temperature below the melting point of aluminum and sintered under a protective gas atmosphere, and to a sintered shaped body made of an aluminum sinter mixture.
- Sintered moldings made of an aluminum-sinter mixture can not only be produced in large quantities with high manufacturing accuracy, but also have a comparatively low specific weight and good corrosion resistance.
- these advantages are offset by the disadvantage of low wear resistance.
- Hard coating by chemical deposition of, for example, titanium carbide, titanium nitride or a boride from the gas phase is, however, not expedient in the case of aluminum materials because the coating processes require reaction temperatures above the melting point of the aluminum.
- wear-resistant layers such as evaporation, ion implantation and. Like., Applied, so generally only thin, quickly removable layers are obtained.
- these methods are too expensive for coating cheap mass parts.
- at least when applying thicker layers the very good dimensional stability of the sintered shaped body is impaired.
- Another way of improving the wear resistance of sintered aluminum moldings is to incorporate more wear-resistant particles into the aluminum matrix.
- an additive made of more wear-resistant, intermetallic compounds for example a Mo-Co-Si alloy, which is pulverized by atomization, to the aluminum sintered mixture, but these proposals have not been successful in practice because the metallic additives react with the matrix material during sintering and brittle intermediate layers form under a comparatively strong sintering swelling. It is practically impossible to control the dimensional change during sintering. In addition, these brittle interlayers break when subjected to wear and the embedded particles crumble out. If you try to store particles in the aluminum matrix that do not react with the matrix and consist, for example, of aluminum oxide, they do not alloy, but they are only poorly integrated and can easily be torn out of the material in the event of wear.
- the invention is therefore based on the object of avoiding these deficiencies and of specifying a method by means of which dimensionally stable sintered shaped bodies can be obtained from an aluminum-sintered mixture with a comparatively high wear resistance.
- the invention achieves the object in that as a powdery additive, oxides, carbides, nitrides, borides or silicates of elements with a melting point above of aluminum are used which are less noble than the corresponding aluminum compound or aluminum with regard to the free enthalpy of reaction and form mixed crystals with the aluminum in the region of the sintering temperature.
- the aluminum of the matrix reduces the surface of the embedded particles.
- this reaction would cease very quickly if mixed crystals could not form which change the activities, so that even with a positive difference in the free enthalpy, such substances with the Aluminum can react.
- this reaction stops after reaching a comparatively low concentration of mixed crystals in the area of the phase interfaces because no more particles can be reduced due to the activity compensation.
- the adhesive layer formed consequently remains very thin because of the small amount converted and, moreover, acts as a diffusion barrier due to the high melting point, as a result of which a further reaction is effectively inhibited by diffusion.
- silicates predominates in the formation of mixed crystals between the aluminum and the silicate component of the silicate.
- silicates of metals which are less noble than aluminum in terms of their free enthalpy the silicate content is reduced, with thin adhesive layers being formed.
- the implementation is coming, however after reaching a certain layer thickness and after the incorporation of some formed aluminum oxide in the surface of the particles practically to a standstill, a further implementation is only possible through a diffusion of aluminum or silicon through the intermediate layer, which however strongly inhibits such diffusion.
- the very low reaction of the non-metallic additive particles with the aluminum matrix practically does not change the sintering behavior of the aluminum sintered mixture compared to the additive-free sintered mixtures. Consequently, the sintering conditions which are advantageous for the production of shaped sintered bodies without wear-reducing additives can also be used for the sintering of the aluminum sintered mixtures with such wear-reducing, non-metallic additives.
- the particles of the powdery additive should have a spherical shape with a grain diameter between 30 and 100 ⁇ m. If the grain diameter is below the specified range, there is no noticeable improvement in wear resistance because the wear-resistant additional particles can be pressed into the matrix structure during wear. In addition, too small a grain size leads to a loss of strength of the shaped bodies. A large number of very fine additional particles hinder the formation of the sinter bridges that determine the strength of the material. If the grain size exceeds a certain dimension, there is a risk that the additional particles will be torn out of the structure. In addition, difficulties can arise with regard to the different thermal expansion coefficients of the non-metallic inclusions and the aluminum matrix.
- the grain diameter of the powdery non-metallic additive is between 50 and 200 ⁇ m lies. Additional particles with a spherical shape ensure better mechanical properties of the sintered molding, in particular a better elongation at break can be achieved. In addition, the green bodies are more compressible and the tool wear when pressing the green bodies is less.
- the content of additional particles should make up at least 0.5% by volume of the sintered mixture. If the powdery additive content rises above 50% by volume, the strength of the sintered materials is impaired. In general, an addition of 1 to 30% by volume of non-metallic substances to the aluminum sintering mixture will ensure the best results.
- the hardness of the non-metallic additives only plays a subordinate role for the wear properties of the sintered molded body, because all the non-metallic substances in question have a sufficiently high hardness.
- the advantages of conventional aluminum sintered shaped bodies can be combined with the advantage of a considerable improvement in wear behavior.
- the adhesive layers that form between the embedded, wear-resistant particles and the matrix are limited in terms of the layer thickness to 0.01 to 1.0 pm, so that, despite the brittle intermetallic phases, ductile behavior is achieved which allows the wear-resistant particles to be incorporated well into the matrix ensures that the material is also subjected to greater wear.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Powder Metallurgy (AREA)
- Compositions Of Oxide Ceramics (AREA)
Abstract
Description
Die Erfindung bezieht sich auf ein Verfahren zum Herstellen von Sinterformkörpern aus einer Aluminium-Sintermischung mit einem Zusatz aus verschleißfesten Pulverteilchen, wobei die Sintermischung zu einem Formkörper gepreßt, auf eine Sintertemperatur unterhalb des Schmelzpunktes von Aluminium erwärmt und unter Schutzgasatmosphäre gesintert wird, sowie auf einen Sinterformkörper aus einer Aluminium-Sintermischung.The invention relates to a process for producing sintered shaped bodies from an aluminum sintered mixture with an addition of wear-resistant powder particles, the sintered mixture being pressed to form a shaped body, heated to a sintering temperature below the melting point of aluminum and sintered under a protective gas atmosphere, and to a sintered shaped body made of an aluminum sinter mixture.
Sinterformkörper aus einer Aluminium-Sintermischung lassen sich nicht nur in großen Stückzahlen mit hoher Fertigungsgenauigkeit herstellen, sondern weisen auch ein vergleichsweise niedriges spezifisches Gewicht und eine gute Korrosionsbeständigkeit auf. Diesen Vorteilen steht allerdings der Nachteil einer geringen Verschleißbeständigkeit gegenüber. Um die Verschleißbeständigkeit zu verbessern, bietet sich die Möglichkeit an, die Sinterformkörper mit einer verschleißfesten Schutzschicht zu überziehen. Eine Hartbeschichtung durch eine chemische Abscheidung beispielsweise von Titankarbid, Titannitrid oder eines Borids aus der Gasphase ist allerdings bei Aluminiumwerkstoffen nicht zielführend, weil die Beschichtungsverfahren Reaktionstemperaturen über dem Schmelzpunkt des Aluminiums erfordern. Werden physikalische Verfahren zum Aufbringen verschleißfester Schichten, wie Aufdampfen, Ionenimplantieren u. dgl., angewandt, so werden im allgemeinen nur dünne, rasch abtragbare Schichten erhalten. Außerdem sind diese Verfahren für eine Beschichtung von billigen Massenteilen zu teuer. Dasselbe gilt auch für die versuchte Aufbringung von galvanischen Schichten. Dazu kommt, daß zumindest beim Aufbringen dickerer Schichten die sehr gute Maßhaltigkeit der Sinterformkörper beeinträchtigt wird.Sintered moldings made of an aluminum-sinter mixture can not only be produced in large quantities with high manufacturing accuracy, but also have a comparatively low specific weight and good corrosion resistance. However, these advantages are offset by the disadvantage of low wear resistance. In order to improve the wear resistance, it is possible to coat the sintered shaped bodies with a wear-resistant protective layer. Hard coating by chemical deposition of, for example, titanium carbide, titanium nitride or a boride from the gas phase is, however, not expedient in the case of aluminum materials because the coating processes require reaction temperatures above the melting point of the aluminum. Are physical methods for applying wear-resistant layers, such as evaporation, ion implantation and. Like., Applied, so generally only thin, quickly removable layers are obtained. In addition, these methods are too expensive for coating cheap mass parts. The same applies to the attempted application of galvanic Layers. In addition, at least when applying thicker layers, the very good dimensional stability of the sintered shaped body is impaired.
Eine andere Möglichkeit, die Verschleißbeständigkeit von Sinterformkörpern aus Aluminium zu verbessern, besteht darin, in die Aluminiummatrix verschleißfestere Teilchen einzulagern. Zu diesem Zweck wurde bereits vorgeschlagen, der Aluminium-Sintermischung einen Zusatz aus verschleißfesteren, intermetallischen Verbindungen, beispielsweise eine Mo-Co-Si-Legierung, die durch ein Verdüsen pulverisiert wird, zuzumischen, doch konnten sich diese Vorschläge in der Praxis nicht durchsetzen, weil die metallischen Zusätze während des Sinterns mit dem Matrixwerkstoff reagieren und sich unter einer vergleichsweise starken Sinterschwellung spröde Zwischenschichten bilden. Es gelingt praktisch nicht, die Maßänderung während des Sinterns zu steuern. Außerdem brechen diese spröden Zwischenschichten bei einer Verschleißbeanspruchung und es kommt zu einem Herausbröckeln der eingelagerten Teilchen. Versucht man, Teilchen in die Aluminiummatrix einzulagern, die mit der Matrix nicht reagieren und beispielsweise aus Aluminiumoxid bestehen, so legieren diese zwar nicht, doch werden sie auch nur schlecht eingebunden und können bei einer Verschleißbeanspruchung leicht aus dem Werkstoff herausgerissen werden.Another way of improving the wear resistance of sintered aluminum moldings is to incorporate more wear-resistant particles into the aluminum matrix. For this purpose, it has already been proposed to add an additive made of more wear-resistant, intermetallic compounds, for example a Mo-Co-Si alloy, which is pulverized by atomization, to the aluminum sintered mixture, but these proposals have not been successful in practice because the metallic additives react with the matrix material during sintering and brittle intermediate layers form under a comparatively strong sintering swelling. It is practically impossible to control the dimensional change during sintering. In addition, these brittle interlayers break when subjected to wear and the embedded particles crumble out. If you try to store particles in the aluminum matrix that do not react with the matrix and consist, for example, of aluminum oxide, they do not alloy, but they are only poorly integrated and can easily be torn out of the material in the event of wear.
Der Erfindung liegt somit die Aufgabe zugrunde, diese Mängel zu vermeiden und ein Verfahren anzugeben, mit dessen Hilfe maßhaltige Sinterformkörper aus einer Aluminium-Sintermischung mit einem vergleichsweise hohen Verschleißwiderstand erhalten werden können.The invention is therefore based on the object of avoiding these deficiencies and of specifying a method by means of which dimensionally stable sintered shaped bodies can be obtained from an aluminum-sintered mixture with a comparatively high wear resistance.
Ausgehend von einem Verfahren der eingangs geschilderten Art löst die Erfindung die gestellte Aufgabe dadurch, daß als pulveriger Zusatz Oxide, Karbide, Nitride, Boride bzw. Silikate von Elementen mit einem Schmelzpunkt über dem des Aluminiums verwendet werden, die hinsichtlich der freien Reaktionsenthalpie unedler als die entsprechende Aluminiumverbindung bzw. das Aluminium sind und mit dem Aluminium im Bereich der Sintertemperatur Mischkristalle bilden.Starting from a method of the type described at the outset, the invention achieves the object in that as a powdery additive, oxides, carbides, nitrides, borides or silicates of elements with a melting point above of aluminum are used which are less noble than the corresponding aluminum compound or aluminum with regard to the free enthalpy of reaction and form mixed crystals with the aluminum in the region of the sintering temperature.
Durch das Aluminium der Matrix wird die Oberfläche der eingelagerten Teilchen anreduziert. Wegen der gegenüber der entsprechenden Aluminiumverbindung bzw. dem Aluminium negativeren freien Reaktionsenthalpie der Zusätze würde diese Reaktion jedoch sehr rasch wieder aufhören, wenn sich nicht Mischkristalle bilden könnten, die die Aktivitäten ändern, so daß auch bei einer positiven Differenz der freien Enthalpie solche Stoffe mit dem Aluminium reagieren können. Diese Reaktion bleibt jedoch schon nach Erreichen einer vergleichsweise geringen Konzentration an Mischkristallen im Bereich der Phasengrenzflächen stehen, weil wegen des Aktivitätsausgleiches keine weiteren Teilchen mehr anreduziert werden können. Die gebildete Haftschicht bleibt folglich wegen der geringen umgesetzten Menge sehr dünn und wirkt darüber hinaus aufgrund des hohen Schmelzpunktes als Diffusionssperre, wodurch eine weitergehende Reaktion durch ein Abdiffundieren wirksam gehemmt wird. Auch wenn intermetallische Phasen von sich aus spröde sind, bleiben die gebildeten Haftschichten zufolge ihrer geringen Dicke verformbar und verhalten sich duktil, so daß die verschleißfesteren Teilchen gut eingebunden und nicht losgerissen werden, was den Verschleißwiderstand solcher Sinterformkörper erheblich vergrößert.The aluminum of the matrix reduces the surface of the embedded particles. However, because of the free reaction enthalpy of the additives, which is more negative than that of the corresponding aluminum compound or aluminum, this reaction would cease very quickly if mixed crystals could not form which change the activities, so that even with a positive difference in the free enthalpy, such substances with the Aluminum can react. However, this reaction stops after reaching a comparatively low concentration of mixed crystals in the area of the phase interfaces because no more particles can be reduced due to the activity compensation. The adhesive layer formed consequently remains very thin because of the small amount converted and, moreover, acts as a diffusion barrier due to the high melting point, as a result of which a further reaction is effectively inhibited by diffusion. Even if intermetallic phases are inherently brittle, the adhesive layers formed remain deformable due to their small thickness and behave ductile, so that the more wear-resistant particles are well integrated and are not torn loose, which considerably increases the wear resistance of such sintered moldings.
Im Gegensatz zu den anderen nichtmetallischen Zusätzen überwiegt bei der Verwendung von Silikaten die Mischkristallbildung zwischen dem Aluminium und dem silikatischen Anteil des Silikates. Bei Silikaten von Metallen, die hinsichtlich der freien Enthalpie unedler als Aluminium sind, wird nämlich der silikatische Anteil anreduziert, wobei sich dünne Haftschichten bilden. Die Umsetzung kommt allerdings nach Erreichen einer bestimmten Schichtstärke und nach dem Einbau von etwas gebildetem Aluminiumoxid in die Oberfläche der Teilchen praktisch zum Stillstand, wobei eine weitere Umsetzung nur durch eine Diffusion von Aluminium bzw. Silizium durch die Zwischenschicht möglich ist, die ein solches Diffundieren jedoch stark hemmt.In contrast to the other non-metallic additives, the use of silicates predominates in the formation of mixed crystals between the aluminum and the silicate component of the silicate. In the case of silicates of metals which are less noble than aluminum in terms of their free enthalpy, the silicate content is reduced, with thin adhesive layers being formed. The implementation is coming, however after reaching a certain layer thickness and after the incorporation of some formed aluminum oxide in the surface of the particles practically to a standstill, a further implementation is only possible through a diffusion of aluminum or silicon through the intermediate layer, which however strongly inhibits such diffusion.
Die sehr geringe Reaktion der nichtmetallischen Zusatzteilchen mit der Aluminiummatrix verändert im Gegensatz von metallischen Zusatzstoffen das Sinterverhalten der Aluminium-Sintermischung gegenüber den zusatzmittelfreien Sintermischungen praktisch nicht. Es können folglich die für die Herstellung von Sinterformkörpern ohne verschleißmindernde Zusätze vorteilhaften Sinterbedingungen auch für das Sintern der Aluminium-Sintermischungen mit solchen verschleißmindernden, nichtmetallischen Zusätzen angewendet werden.In contrast to metallic additives, the very low reaction of the non-metallic additive particles with the aluminum matrix practically does not change the sintering behavior of the aluminum sintered mixture compared to the additive-free sintered mixtures. Consequently, the sintering conditions which are advantageous for the production of shaped sintered bodies without wear-reducing additives can also be used for the sintering of the aluminum sintered mixtures with such wear-reducing, non-metallic additives.
Zur Erzielung einer guten Verschleißbeständigkeit sollen die Teilchen des pulverigen Zusatzes kugelige Gestalt mit einem Korndurchmesser zwischen 30 und 100 um aufweisen. Liegt der Korndurchmesser unter dem angegebenen Bereich, ergibt sich keine merkbare Verbesserung der Verschleißbeständigkeit, weil die verschleißfesten Zusatzteilchen während der Verschleißbeanspruchung in das Matrixgrundgefüge eingedrückt werden können. Außerdem führt eine zu geringe Korngröße zu einem Festigkeitsverlust der Formkörper. Eine große Anzahl sehr feiner Zusatzteilchen behindert nämlich die Ausbildung der die Festigkeit des Werkstoffes bestimmenden Sinterbrücken. Übersteigt die Korngröße ein bestimmtes Maß, so besteht die Gefahr, daß die Zusatzteilchen aus dem Gefüge herausgerissen werden. Darüber hinaus können sich bereits Schwierigkeiten hinsichtlich der unterschiedlichen Wärmedehnungskoeffizienten der nichtmetallischen Einlagerungen und der Aluminiummatrix ergeben. Besonders vorteilhafte Bedingungen werden erhalten, wenn der Korndurchmesser des pulverigen nichtmetallischen Zusatzes zwischen 50 und 200 pm liegt. Zusatzteilchen mit kugeliger Gestalt stellen bessere mechanische Eigenschaften des Sinterformkörpers sicher, wobei insbesondere eine bessere Bruchdehnung erreicht werden kann. Außerdem ist die Verpreßbarkeit der Grünlinge größer und der Werkzeugverschleiß beim Verpressen der Grünlinge geringer.In order to achieve good wear resistance, the particles of the powdery additive should have a spherical shape with a grain diameter between 30 and 100 μm. If the grain diameter is below the specified range, there is no noticeable improvement in wear resistance because the wear-resistant additional particles can be pressed into the matrix structure during wear. In addition, too small a grain size leads to a loss of strength of the shaped bodies. A large number of very fine additional particles hinder the formation of the sinter bridges that determine the strength of the material. If the grain size exceeds a certain dimension, there is a risk that the additional particles will be torn out of the structure. In addition, difficulties can arise with regard to the different thermal expansion coefficients of the non-metallic inclusions and the aluminum matrix. Particularly advantageous conditions are obtained when the grain diameter of the powdery non-metallic additive is between 50 and 200 μm lies. Additional particles with a spherical shape ensure better mechanical properties of the sintered molding, in particular a better elongation at break can be achieved. In addition, the green bodies are more compressible and the tool wear when pressing the green bodies is less.
Um eine wirksame Verbesserung des Verschleißverhaltens des Sinterwerkstoffes zu erhalten, soll der Gehalt an Zusatzteilchen wenigstens 0,5 Vol % der Sintermischung ausmachen. Steigt der Gehalt an pulverigem Zusatz über 50 Vol % an, wird die Festigkeit der Sinterwerkstoffe beeinträchtigt. Im allgemeinen wird daher ein Zusatz an nichtmetallischen Stoffen von 1 bis 30 Vol % zur Aluminium-Sintermischung die besten Ergebnisse sicherstellen.In order to obtain an effective improvement in the wear behavior of the sintered material, the content of additional particles should make up at least 0.5% by volume of the sintered mixture. If the powdery additive content rises above 50% by volume, the strength of the sintered materials is impaired. In general, an addition of 1 to 30% by volume of non-metallic substances to the aluminum sintering mixture will ensure the best results.
Die Härte der nichtmetallischen Zusatzstoffe spielt für die Verschleißeigenschaften des Sinterformkörpers nur eine untergeordnete Rolle, weil alle in Frage kommenden, nichtmetallischen Stoffe eine ausreichend hohe Härte aufweisen.The hardness of the non-metallic additives only plays a subordinate role for the wear properties of the sintered molded body, because all the non-metallic substances in question have a sufficiently high hardness.
Bei einem Sinterforakörper, bei dem in der Aluminiummatrix Oxide, Karbide, Nitride, Boride und/oder Silikate von Elementen mit einen Schmelzpunkt über dem des Aluminiums eingebaut sind, die hinsichtlich der freien Reaktionsenthalpie unedler als die entsprechende Aluminiumverbindung bzw. das Aluminium sind und mit dem Aluminium im Bereich der Sintertemperatur Mischkristalle bilden, können somit die Vorteile herkömmlicher Aluminium-Sinterformkörper mit dem Vorteil einer erheblichen Verbesserung im Verschleißverhalten verbunden werden. Die sich bildenden Haftschichten zwischen den eingelagerten, verschleißfesten Teilchen und der Matrix ist hinsichtlich der Schichtdicke auf 0,01 bis 1,0 pm beschränkt, so daß trotz der spröden intermetallischen Phasen ein duktiles Verhalten erzielt wird, das eine gute Einbindung der verschleißfesten Teilchen in die Matrix auch bei größeren Verschleißbeanspruchungen des Werkstoffes sicherstellt.In a sintered fora body in which the aluminum matrix contains oxides, carbides, nitrides, borides and / or silicates of elements with a melting point above that of aluminum, which are less noble than the corresponding aluminum compound or aluminum with regard to the free enthalpy of reaction and with which If aluminum forms mixed crystals in the area of the sintering temperature, the advantages of conventional aluminum sintered shaped bodies can be combined with the advantage of a considerable improvement in wear behavior. The adhesive layers that form between the embedded, wear-resistant particles and the matrix are limited in terms of the layer thickness to 0.01 to 1.0 pm, so that, despite the brittle intermetallic phases, ductile behavior is achieved which allows the wear-resistant particles to be incorporated well into the matrix ensures that the material is also subjected to greater wear.
- 1. Eine handelsübliche Aluminium-Sintermischung, die 1,5 Gew % eines Preßhilfsmittels enthält, wird in einem Taumelmischer mit 10 Gew % (= ca. 10 Vol %) handelsüblicher Glasperlen mit einer Korngröße von 50 bis 150 pm während zweier Stunden gemischt. Diese Aluminium-Sintermischung wird in herkömmlicher Weise mit entsprechenden Werkzeugen unter einem Druck von 3,5 t/cm2 zu Formteilen gepreßt, die eine hohe Grünfestigkeit und eine hohe Preßdichte aufweisen. Bei dem gewählten Preßdruck und der Zusatzmenge an Glaskugeln ist kein Bruch der Glaskugeln während der Verpressung zu befürchten. Die so hergestellten Grünlinge werden nach einem Entwachsen während 20 Minuten bei 590° C gesintert. Bei einer Sinterschwindung von weniger als 0,1 % werden Formkörper mit einer Zugfestigkeit von 140 N/mm2 (T1-Zustand) bzw. 240 N/mm2 (T6-Zustand) erhalten. Der auf einem Verschleißprüfstand gegenüber einer kunststoffgebundenen Siliziumkarbidscheibe gemessene Verschleiß konnte durch die Silikateinlagerung gegenüber Aluminium-Sinterkörpern ohne diesen Zusatz auf ca. 45 % herabgesetzt werden.1. A commercially available aluminum sintering mixture which contains 1.5% by weight of a pressing aid is mixed in a tumble mixer with 10% by weight (= approximately 10% by volume) of commercially available glass beads with a grain size of 50 to 150 μm for two hours. This aluminum sintered mixture is pressed in a conventional manner with appropriate tools under a pressure of 3.5 t / cm 2 to give molded parts which have a high green strength and a high compression density. With the selected pressing pressure and the additional amount of glass balls, there is no fear of the glass balls breaking during the pressing. The green compacts thus produced are sintered at 590 ° C. for 20 minutes after dewaxing. With a sintering shrinkage of less than 0.1%, moldings with a tensile strength of 140 N / mm 2 (T1 state) or 240 N / mm 2 (T6 state) are obtained. The wear measured on a wear test bench compared to a plastic-bonded silicon carbide disc could be reduced to approx. 45% by adding silicate to aluminum sintered bodies without this addition.
- 2. Zu einer handelsüblichen Aluminium-Sintermischung werden entsprechend dem Beispiel 1 ein handelsübliches Zirkoniumsilikat von 20 Gew % (= ca. 15 Vol %) mit einem Korndurchmesser von 80 bis 100 pm zugemischt. Nach einem Verpressen dieser Sintermischung zu Grünlingen mit einem Druck von 3,5 t/cm2 wurden die Grünlinge bei einer Sintertemperatur von 595° C und einer Sinterzeit von 20 Minuten gesintert. Die Festigkeit der so erhaltenen Sinterformkörper betrug 145 N/mm2 (T1) und 250 N/mm2 (T6). Die Maßänderung beim Sintern wurde mit ± 0,1 % bestimmt. Die Vergrößerung des Verschleißwiderstandes gegenüber zusatzfreien Sinterformkörpern wurde mit 35 % gemessen.2. According to Example 1, a commercially available zirconium silicate of 20% by weight (= approx. 15% by volume) with a grain diameter of 80 to 100 μm is mixed into a commercially available aluminum sintering mixture. After this sintered mixture was pressed into green compacts with a pressure of 3.5 t / cm 2 , the green compacts were sintered at a sintering temperature of 595 ° C. and a sintering time of 20 minutes. The strength of the so obtained Sintered shaped bodies were 145 N / mm 2 (T1) and 250 N / mm 2 (T6). The dimensional change during sintering was determined to be ± 0.1%. The increase in wear resistance compared to sintered moldings free of additives was measured at 35%.
- 3. Bei einem Zusatz von 20 Gew % an handelsüblichem Elektrokorundpulver mit geringem Fe-Gehalt, Korndurchmesser 100 bis 150 µm konnten aus einer handelsüblichen Aluminium-Sintermischung nach einer Vorbereitung entsprechend dem Beispiel 1 nach einer Sinterzeit von 30 Minuten und einer Sintertemperatur von 595° C Sinterformkörper erhalten werden, die eine sehr geringe Sinterschwellung von 0,1 bis 0,2 % aufwiesen. Die Verschleißbeständigkeit konnte gegenüber zusatzmittelfreier Vergleichsproben um ca. 10 % verbessert werden. Die Festigkeit betrug 120 N/mm2 (T1) und 220 N/mmz (T6).3. With the addition of 20% by weight of commercially available electro-corundum powder with a low Fe content, grain diameter 100 to 150 µm, a commercially available aluminum-sinter mixture after preparation according to Example 1 after a sintering time of 30 minutes and a sintering temperature of 595 ° C. Sintered moldings are obtained which have a very low sintering swelling of 0.1 to 0.2%. The wear resistance could be improved by approx. 10% compared to additive-free comparison samples. The strength was 120 N / mm 2 (T1) and 220 N / mm z (T6).
- 4. Mit einer Zugabe von 20 Gew % eines handelsüblichen Siliziumkarbidpulvers mit einer Korngröße von ca. 100 um zu einer üblichen Aluminium-Sintermischung wurden unter den üblichen Preß- und Sinterbedigungen (Preßdruck: 3,5 t/cm2, Sinterzeit: 20 Minuten, Sintertemperatur: 590° C) bei einem geringen Sinterschwund von 0,2 % Sinterformkörper hergestellt, deren Festigkeit 155 N/mm2 (T1) und 265 N/mm2 (T6) betrug. Gegenüber zusatzmittelfreien Vergleichsproben konnte eine Verbesserung des Verschleißverhaltens um 5 % festgestellt werden.4. With the addition of 20% by weight of a commercially available silicon carbide powder with a grain size of approximately 100 .mu.m to a customary aluminum sintering mixture, under the usual pressing and sintering conditions (pressing pressure: 3.5 t / cm 2 , sintering time: 20 minutes, Sintering temperature: 590 ° C.) with a low sintering shrinkage of 0.2% sintered molded body, the strength of which was 155 N / mm 2 (T1) and 265 N / mm 2 (T6). Compared to additive-free comparison samples, an improvement in wear behavior of 5% was found.
Claims (6)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT2204/85 | 1985-07-25 | ||
| AT220485 | 1985-07-25 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0213113A1 true EP0213113A1 (en) | 1987-03-04 |
| EP0213113B1 EP0213113B1 (en) | 1990-12-12 |
Family
ID=3529932
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP86890217A Expired - Lifetime EP0213113B1 (en) | 1985-07-25 | 1986-07-24 | Method of producing sintered bodies from an aluminium sinter mixture |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0213113B1 (en) |
| AT (1) | ATE59064T1 (en) |
| DE (1) | DE3676131D1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0588439A1 (en) * | 1992-09-17 | 1994-03-23 | Mifa Aluminium B.V. | A method of manufacturing objects based on aluminium |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB721821A (en) * | 1948-09-06 | 1955-01-12 | British Aluminium Co Ltd | Improvements in the manufacture of aluminium alloys |
| DE2253282B1 (en) * | 1972-10-31 | 1973-08-16 | Mahle Gmbh, 7000 Stuttgart | Heat-resistant aluminum sintered alloy |
| US3885959A (en) * | 1968-03-25 | 1975-05-27 | Int Nickel Co | Composite metal bodies |
| EP0178046A1 (en) * | 1984-08-13 | 1986-04-16 | Ae Plc | Aluminium or aluminium alloy reinforced by zirconia and process for the manufacture of this material |
| EP0191707A1 (en) * | 1985-02-01 | 1986-08-20 | Cegedur Societe De Transformation De L'aluminium Pechiney | Process for the powder-metallurgical preparation of an aluminium-based material containing at least one ceramic for the manufacture of articles subject to friction |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4557893A (en) * | 1983-06-24 | 1985-12-10 | Inco Selective Surfaces, Inc. | Process for producing composite material by milling the metal to 50% saturation hardness then co-milling with the hard phase |
-
1986
- 1986-07-24 EP EP86890217A patent/EP0213113B1/en not_active Expired - Lifetime
- 1986-07-24 AT AT86890217T patent/ATE59064T1/en not_active IP Right Cessation
- 1986-07-24 DE DE8686890217T patent/DE3676131D1/en not_active Expired - Lifetime
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB721821A (en) * | 1948-09-06 | 1955-01-12 | British Aluminium Co Ltd | Improvements in the manufacture of aluminium alloys |
| US3885959A (en) * | 1968-03-25 | 1975-05-27 | Int Nickel Co | Composite metal bodies |
| DE2253282B1 (en) * | 1972-10-31 | 1973-08-16 | Mahle Gmbh, 7000 Stuttgart | Heat-resistant aluminum sintered alloy |
| EP0178046A1 (en) * | 1984-08-13 | 1986-04-16 | Ae Plc | Aluminium or aluminium alloy reinforced by zirconia and process for the manufacture of this material |
| EP0191707A1 (en) * | 1985-02-01 | 1986-08-20 | Cegedur Societe De Transformation De L'aluminium Pechiney | Process for the powder-metallurgical preparation of an aluminium-based material containing at least one ceramic for the manufacture of articles subject to friction |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0588439A1 (en) * | 1992-09-17 | 1994-03-23 | Mifa Aluminium B.V. | A method of manufacturing objects based on aluminium |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0213113B1 (en) | 1990-12-12 |
| DE3676131D1 (en) | 1991-01-24 |
| ATE59064T1 (en) | 1990-12-15 |
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