EP0214679B2 - Oxidation-resistant hard metal alloy - Google Patents
Oxidation-resistant hard metal alloy Download PDFInfo
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- EP0214679B2 EP0214679B2 EP19860201344 EP86201344A EP0214679B2 EP 0214679 B2 EP0214679 B2 EP 0214679B2 EP 19860201344 EP19860201344 EP 19860201344 EP 86201344 A EP86201344 A EP 86201344A EP 0214679 B2 EP0214679 B2 EP 0214679B2
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- alloy
- carbide
- hard metal
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- 229910001092 metal group alloy Inorganic materials 0.000 title description 19
- 230000003647 oxidation Effects 0.000 title 1
- 238000007254 oxidation reaction Methods 0.000 title 1
- 229910045601 alloy Inorganic materials 0.000 claims description 40
- 239000000956 alloy Substances 0.000 claims description 40
- 230000007797 corrosion Effects 0.000 claims description 32
- 238000005260 corrosion Methods 0.000 claims description 32
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 22
- 239000011230 binding agent Substances 0.000 claims description 18
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 claims description 14
- 239000011651 chromium Substances 0.000 claims description 11
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 10
- 229910052804 chromium Inorganic materials 0.000 claims description 10
- 229910017052 cobalt Inorganic materials 0.000 claims description 10
- 239000010941 cobalt Substances 0.000 claims description 10
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 10
- 229910052759 nickel Inorganic materials 0.000 claims description 10
- 239000000463 material Substances 0.000 claims description 6
- 238000010276 construction Methods 0.000 claims description 3
- 229910003468 tantalcarbide Inorganic materials 0.000 claims description 3
- 238000002485 combustion reaction Methods 0.000 claims description 2
- UNASZPQZIFZUSI-UHFFFAOYSA-N methylidyneniobium Chemical compound [Nb]#C UNASZPQZIFZUSI-UHFFFAOYSA-N 0.000 claims description 2
- NFFIWVVINABMKP-UHFFFAOYSA-N methylidynetantalum Chemical compound [Ta]#C NFFIWVVINABMKP-UHFFFAOYSA-N 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims description 2
- 239000012071 phase Substances 0.000 description 17
- 229910052751 metal Inorganic materials 0.000 description 9
- 239000002184 metal Substances 0.000 description 9
- 239000000203 mixture Substances 0.000 description 7
- 150000001247 metal acetylides Chemical class 0.000 description 6
- 229910052750 molybdenum Inorganic materials 0.000 description 6
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 5
- 239000011733 molybdenum Substances 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 150000002739 metals Chemical class 0.000 description 4
- 238000001000 micrograph Methods 0.000 description 4
- 230000001427 coherent effect Effects 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 239000010955 niobium Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000000788 chromium alloy Substances 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000007676 flexural strength test Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- -1 hafnium carbides Chemical class 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910000623 nickel–chromium alloy Inorganic materials 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 229910003470 tongbaite Inorganic materials 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
- C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
- C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
- C22C29/067—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds comprising a particular metallic binder
Definitions
- the invention relates to a hard metal alloy which, in addition to high mechanical strength and high wear resistance, is extremely corrosion-resistant.
- carbide grades of the most varied composition of carbide and binder phase are known.
- the most common types of hard metal used so far for machining are those based on tungsten carbide with a binding phase made of cobalt or nickel.
- These carbide grades have good mechanical strength and wear resistance, but are not very corrosion-resistant, especially in acidic media.
- the cobalt or nickel binder is particularly exposed to a strong corrosion attack, which leads to a selective dissolution of the binding phase. Subsequently, the strength of the remaining carbide skeleton suddenly drops.
- EP-A 28 620 is a corrosion-resistant tungsten carbide-based hard metal alloy in which a maximum of 10% of the tungsten carbide can be replaced by additional carbides.
- the binder alloys which contain 5-45%, consist of at least 50 vol.% Nickel, 2-25 vol.% Chromium and 1-15 vol.% Molybdenum.
- the binding phase can also contain one or more of the elements Mn, Al, Si, Cu, Co, Fe and W.
- the tungsten carbide content of this hard metal alloy is at least 88.5% by weight.
- This carbide alloy additionally contains one or more carbides from the group of titanium, niobium and hafnium carbides with a maximum proportion of 8.5% by weight.
- the binder phase which is added to the basic component in an amount of 3-11.5% by weight, has as essential components 20-75% by weight cobalt, 4-50% by weight chromium and up to 45% by weight nickel.
- one or more additional elements from the group W, Mo, Fe, Si, B, C, Ti, Zr, Nb and / or V are included.
- a third hard metal alloy in which chromium is added to the binder phase, is described in US Pat. No. 3,993,446.
- This hard metal alloy consists of 70-90% by weight of tungsten carbide-based hard materials, some of which can be replaced by an additional carbide.
- the binding phase which is 10-30% by weight, consists of 20-90% by weight of nickel, 10-80% by weight of cobalt and 5-25% by weight of chromium.
- the object of the present invention is to propose a highly corrosion-resistant hard metal alloy which at the same time has a high mechanical strength and a high wear resistance or corrosion resistance against chemically aggressive media.
- this object is achieved by using a hard metal alloy as a material for components with high corrosion resistance against chemically aggressive media.
- a hard metal alloy consists of 44-67% by weight of tungsten carbide, 30-50% by weight of tantalum carbide and / or niobium carbide and 3-6% by weight of a binding alloy consisting of nickel and / or cobalt, each with 2-20% by weight of chromium.
- the binding phase forms a coherent skeleton.
- Corrosive media can release the entire binding phase if the exposure time is long enough.
- a tungsten carbide scaffold remains, which has a low strength and which is quickly removed under abrasive stress.
- a corrosion-improving alloy of the binding phase with chromium and / or molybdenum changes only little about this undesirable property.
- the corrosion resistance is increased, but the binding phase still forms a coherent framework, so that a corrosive medium can work its way along fine channels into the interior of the alloy.
- this fact leads to an early destruction of the entire hard metal alloy.
- the high corrosion resistance of the alloy according to the invention can be explained by the fact that the binding phase does not form a coherent skeleton due to the high additional carbide content. This significantly reduces the effectiveness of the corrosion attack, especially since the tungsten carbide and the listed additional carbides themselves have very good corrosion resistance in acidic media.
- Table 1 shows the comparison of the mechanical properties of alloys of different compositions according to the prior art and alloys of different compositions according to the present invention.
- the table shows in particular that most of the alloys according to the invention have significantly better hardness and flexural strength values than alloy 6, which is considered the best alloy according to the prior art in terms of its corrosion resistance.
- the alloy according to the invention can be produced without problems using known powder metallurgy processes, despite the low binder content.
- the additional carbides can be added either individually or in the form of mixed carbide crystals. It is also possible to introduce the tungsten carbide as a single crystal or as a mixed crystal with an additional carbide.
- the advantageous properties can be further improved by a special optimization of the powder metallurgical manufacturing process of the alloy according to the invention. It is essential in this optimized manufacturing process to sinter the alloy at the lowest possible temperatures for as short a time as possible, but the formation of a liquid phase during sintering must not be prevented. The residual porosities remaining through this type of sintering are then closed by hot isostatic post-compression.
- This optimized production process achieves the desired discontinuous division of the binder phase on the one hand, and on the other hand the grain growth of the carbide phase can be kept as low as possible, which leads to a further increase in hardness of the hard metal alloy according to the invention.
- the mixture was ground in a ball mill in 2.5 l of acetone for 120 h. After the batch powder had been dried, molded articles were produced, from which various samples for corrosion tests, flexural strength tests and the like were produced. were formed. These samples were sintered in vacuo at 1450 ° C. for 40 minutes and subsequently hot isostatically compressed.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Powder Metallurgy (AREA)
Description
Die Erfindung betrifft eine Hartmetall-Legierung, die neben hoher mechanischer Festigkeit und hoher Verschleißfestigkeit äußerst korrosionsfest ist.The invention relates to a hard metal alloy which, in addition to high mechanical strength and high wear resistance, is extremely corrosion-resistant.
Es ist eine Vielzahl von Hartmetall-Sorten der unterschiedlichsten Zusammensetzung von Karbid- und Bindephase bekannt. Die bisher am häufigsten, vorzugsweise bei der Zerspanung eingesetzten Hartmetall-Sorten sind diejenigen auf Wolframkarbid-Basis mit einer Bindephase aus Kobalt oder Nickel. Diese Hartmetall- sorten weisen eine gute mechanische Festigkeit und Verschleißbeständigkeit auf, sind jedoch insbesonders in sauren Medien nicht sehr korrosionsbeständig. Dabei ist besonders der Kobalt- oder Nickelbinder einem starken Korrosionsangriff ausgesetzt, was zu einer selektiven Auflösung der Bindephase führt. In der weiteren Folge vermindert sich dann die Festigkeit des verbleibenden Karbidskeletts sprunghaft.A large number of carbide grades of the most varied composition of carbide and binder phase are known. The most common types of hard metal used so far for machining are those based on tungsten carbide with a binding phase made of cobalt or nickel. These carbide grades have good mechanical strength and wear resistance, but are not very corrosion-resistant, especially in acidic media. The cobalt or nickel binder is particularly exposed to a strong corrosion attack, which leads to a selective dissolution of the binding phase. Subsequently, the strength of the remaining carbide skeleton suddenly drops.
Es hat in der Vergangenheit nicht an Versuchen gefehlt, die Korrosionsbeständigkeit von Hartmetall zu verbessern. Ein Versuch in dieser Richtung war, den Kobalt- oder Nickelbinder durch korrosionsfeste Metalle wie Gold oder Platin zu ersetzen. Derartige Hartmetall-Legierungen haben sich jedoch allein schon aufgrund der hohen Kosten in der Praxis nicht durchsetzen können. In der weiteren Folge wurde versucht, die Korrosionsfestigkeit von Hartmetallen durch Zulegieren von korrosionsfesten Elementen wie Chrom und Molybdän zu verbessern.There has been no shortage of attempts in the past to improve the corrosion resistance of hard metal. One attempt in this direction was to replace the cobalt or nickel binder with corrosion-resistant metals such as gold or platinum. Such hard metal alloys, however, have not been able to gain acceptance in practice simply because of the high costs involved. Subsequently, attempts were made to improve the corrosion resistance of hard metals by alloying corrosion-resistant elements such as chromium and molybdenum.
So beschreibt z.B. die EP-A 28 620 eine korrosionsfeste Hartmetall-Legierung auf Wolframkarbid-Basis, bei der maximal 10 % des Wolframkarbids durch Zusatzkarbide ersetzt sein können. Die Binderlegierungen, die zu 5-45 % enthalten ist, besteht aus zumindestens 50 Vol.% Nickel, aus 2-25 Vol.% Chrom und aus 1-15 Vol.% Molybdän. Zusätzlich kann die Bindephase noch eines oder mehrere der Elemente Mn, Al, Si, Cu, Co, Fe und W enthalten.For example, EP-A 28 620 is a corrosion-resistant tungsten carbide-based hard metal alloy in which a maximum of 10% of the tungsten carbide can be replaced by additional carbides. The binder alloys, which contain 5-45%, consist of at least 50 vol.% Nickel, 2-25 vol.% Chromium and 1-15 vol.% Molybdenum. In addition, the binding phase can also contain one or more of the elements Mn, Al, Si, Cu, Co, Fe and W.
Eine weitere korrosionsfeste Hartmetall-Legierung auf Wolframkarbid-Basis beschreibt die DE-A 14 83 230. Der Wolframkarbidgehalt dieser Hartmetall-Legierung beträgt zumindest 88,5 Gew.%. Zusätzlich sind in dieser Hartmetall-Legierung ein oder mehrere Karbide aus der Gruppe der Titan-, Niob- und Hafniumkarbide mit einem Maximal-Anteil von 8,5 Gew.% enthalten. Die Bindemittelphase, die in einer Menge von 3-11,5 Gew.% zur Grundkomponente zugesetzt ist, weist als wesentliche Bestandteile 20-75 Gew.% Kobalt, 4-50 Gew.% Chrom und bis zu 45 Gew.% Nickel auf. Daneben sind ein oder mehrere Zusatzelemente aus der Gruppe W, Mo, Fe, Si, B, C, Ti, Zr, Nb und/oder V enthalten.Another corrosion-resistant hard metal alloy based on tungsten carbide is described in DE-A 14 83 230. The tungsten carbide content of this hard metal alloy is at least 88.5% by weight. This carbide alloy additionally contains one or more carbides from the group of titanium, niobium and hafnium carbides with a maximum proportion of 8.5% by weight. The binder phase, which is added to the basic component in an amount of 3-11.5% by weight, has as essential components 20-75% by weight cobalt, 4-50% by weight chromium and up to 45% by weight nickel. In addition, one or more additional elements from the group W, Mo, Fe, Si, B, C, Ti, Zr, Nb and / or V are included.
Eine dritte Hartmetall-Legierung, bei der der Binderphase Chrom zulegiert ist, ist in der US-A 3,993 446 beschrieben. Diese Hartmetall-Legierung besteht zu 70-90 Gew.% aus Hartstoffen auf Wolframkarbid-Basis, die teilweise durch ein Zusatzkarbid ersetzt sein können. Die Bindephase, die 10-30 Gew.% beträgt, besteht aus 20-90 Gew.% Nickel, 10-80 Gew.% Kobalt und 5-25 Gew.% Chrom.A third hard metal alloy, in which chromium is added to the binder phase, is described in US Pat. No. 3,993,446. This hard metal alloy consists of 70-90% by weight of tungsten carbide-based hard materials, some of which can be replaced by an additional carbide. The binding phase, which is 10-30% by weight, consists of 20-90% by weight of nickel, 10-80% by weight of cobalt and 5-25% by weight of chromium.
Allen diesen Hartmetall-Legierungen ist gemeinsam, daß es durch das Zulegieren von Chrom und/oder Molybdän zur Bindephase zwar zu gewissen Verbesserungen in der Korriosionsbeständigkeit kommt. Die Möglichkeit der Zulegierung von Chrom und Molybdän ist aus metallurgischen Gründen jedoch begrenzt, da bei höheren Anteilen dieser Elemente die Herstellbarkeit dieser Legierungen erschwert oder sogar unmöglich gemacht wird. Aufgrund versprödender Phasen sinkt darüberhinaus die mechanische Festigkeit dieser Hartmetalle stark ab und führt bei ihrer mechanischen Bearbeitung oder bei ihrem Einsatz häufig zu Bruch und Ausbrüchen.All these hard metal alloys have in common that the addition of chromium and / or molybdenum to the binding phase leads to certain improvements in the resistance to corrosion. However, the possibility of alloying chromium and molybdenum is limited for metallurgical reasons, since the higher the proportions of these elements make it difficult or even impossible to manufacture these alloys. Due to embrittling phases, the mechanical strength of these hard metals also drops sharply and often leads to breakage and chipping when they are machined or used.
Ein weiterer Weg, die Korrosionsfestigkeit von Hartmetall-Legierungen zu steigern, wurde in der Minimierung des Bindemetallgehaltes gesehen. Die Minimierung des Bindemetallgehaltes führte jedoch zu Sinterproblemen und in der Folge zu erhöhter Porösität und bewirkt ebenfalls einen gravierenden Verlust an mechanischer Festigkeit, so daß auch dieser Weg nicht erfolgreich war.Another way to increase the corrosion resistance of hard metal alloys was seen in minimizing the binder metal content. The minimization of the binder metal content, however, led to sintering problems and consequently to increased porosity and also causes a serious loss in mechanical strength, so that this route was also unsuccessful.
R. Kieffer, F. Benesovsky "Hartmetalle", Springer-Verlag, Wien, 1965 nennt an einer Stelle eine Reihe von Hartmetall-Legierungen bestehend aus 34-78 % WC, 16-60% Tic und 6-8 % Co-Bindermetall, Gemäß einer anderen Stelle des "Buches kann" man die Korrosionsbeständigkeit erhöhen, indem man in solchen legierungen das Kobalt durch Nickel-Chrom-Legierungen 80/20 oder 70/30 ersetzt.R. Kieffer, F. Benesovsky "Hartmetalle", Springer-Verlag, Vienna, 1965 mentions a number of hard metal alloys consisting of 34-78% WC, 16-60% Tic and 6-8% co-binder metal, According to another passage in the "book", the corrosion resistance can be increased by replacing the cobalt in such alloys with nickel-chromium alloys 80/20 or 70/30.
Die Aufgabe der vorliegenden Erfindung ist es, eine hochkorrosionsfeste Hartmetall-Legierung vorzuschlagen, die gleichzeitig eine hohe mechanische Festigkeit und eine hohe Verschleißfestigkeit bzw. Korrosionsfestigkeit gegen chemisch aggressive Medien aufweist.The object of the present invention is to propose a highly corrosion-resistant hard metal alloy which at the same time has a high mechanical strength and a high wear resistance or corrosion resistance against chemically aggressive media.
Erfindungsgemäß wird diese Aufgabe durch die Verwendung einer Hartmetall-Legierung als Werkstoff für Bauteile mit hoher Korrosionsfestigkeit gegen chemisch aggressive Medien gelöst. Diese besteht aus 44-67 Gew.% Wolframkarbid, 30-50 Gew.% Tantalkarbid und/oder Niobkarbid sowie 3-6 Gew.% einer Bindelegierung, bestehend aus Nickel und/oder Kobalt mit jeweils 2-20 Gew.% Chrom.According to the invention, this object is achieved by using a hard metal alloy as a material for components with high corrosion resistance against chemically aggressive media. This consists of 44-67% by weight of tungsten carbide, 30-50% by weight of tantalum carbide and / or niobium carbide and 3-6% by weight of a binding alloy consisting of nickel and / or cobalt, each with 2-20% by weight of chromium.
Entscheidend für die vorliegende Erfindung ist, daß die guten Eigenschaften der Hartmetall-Legierung völlig überraschend durch einen hohen Anteil an Zweitkarbiden erreicht wurden. Bisher bekannte korrosionsfeste Hartmetallsorten enthalten demgegenüber nur einen vergleichsweise geringen Anteil an Zusatzkarbiden.It is crucial for the present invention that the good properties of the hard metal alloy were achieved completely surprisingly by a high proportion of secondary carbides. In contrast, previously known corrosion-resistant carbide grades contain only a comparatively small proportion of additional carbides.
Die Eigenschafts-Verbesserungen der erfindungsgemäßen Hartmetallsorte sind herausragend und waren in ihrem Ausmaß in keiner Weise vorhersehbar. Dabei zeigen verschiedene Hartmetall-Legierungen innerhalb der erfindungsgemäßen Zusammensetzung durchaus unterschiedliche, nicht immer gegenüber allen korrosiven Medien gleich vorteilhafte Eigenschaften.The property improvements of the carbide grade according to the invention are outstanding and their extent was in no way predictable. Various hard metal alloys within the composition according to the invention exhibit entirely different properties which are not always equally advantageous compared to all corrosive media.
Bei den bekannten Hartmetallsorten auf Wolframkarbidbasis mit Kobalt- oder Nickelbinder bildet die Bindephase ein zusammenhängendes Skelett. Korrosive Medien können also bei genügend langer Einwirkungsdauer die gesamte Bindephase herauslösen. Es bleibt danach ein Wolframkarbid-Gerust über, das eine geringe Festigkeit aufweist und das bei abrasiver Beanspruchung schnell abgetragen wird. Eine korrosionsverbessernde Legierung der Bindephase mit Chrom und/oder Molybdän ändert an dieser unerwünschten Eigenschaft nur wenig. Die Korrosionsbeständigkeit ist zwar erhöht, aber die Bindephase bildet nach wie vor ein zusammenhängendes Gerüst, so daß sich ein korrosives Medium entlang feiner Kanale in das Innere der Legierung vorarbeiten kann. Diese Tatsache führt wie bei den Wolframkarbid-Hartmetallen mit reinem Kobalt-oder Nickelbinder zu einer baldigen Zerstörung der gesamten Hartmetall-Legierung.In the known types of tungsten carbide carbide with cobalt or nickel binder, the binding phase forms a coherent skeleton. Corrosive media can release the entire binding phase if the exposure time is long enough. After that, a tungsten carbide scaffold remains, which has a low strength and which is quickly removed under abrasive stress. A corrosion-improving alloy of the binding phase with chromium and / or molybdenum changes only little about this undesirable property. The corrosion resistance is increased, but the binding phase still forms a coherent framework, so that a corrosive medium can work its way along fine channels into the interior of the alloy. As with tungsten carbide hard metals with pure cobalt or nickel binder, this fact leads to an early destruction of the entire hard metal alloy.
Die hohe Korrosionsfestigkeit der erfindungsgemäßen Legierung ist damit zu erklären, daß infolge des hohen Zusatzkarbid-Gehaltes die Bindephase kein zusammenhängendes Skelett ausbildet. Dadurch ist der Korrosionsangriff in seiner Wirksamkeit entscheidend vermindert, zumal das Wolframkarbid sowie die aufgeführten Zusatzkarbide selbst eine sehr gute Korrosionsbeständigkeit in sauren Medien aufweisen.The high corrosion resistance of the alloy according to the invention can be explained by the fact that the binding phase does not form a coherent skeleton due to the high additional carbide content. This significantly reduces the effectiveness of the corrosion attack, especially since the tungsten carbide and the listed additional carbides themselves have very good corrosion resistance in acidic media.
Der erfindungsgemäße hohe Anteil eines bestimmten Zusatzkarbides zum Wolframkarbid in Verbindung mit einer ganz spezifischen Binderlegierung ergibt neben einer sprunghaften Erhöhung der Korrosionsfestigkeit zudem auch mechanische Festigkeitseigenschaften und Verschleißeigenschaften, welche denen bekannter korrosionsfester Hartmetall-Legierungen mit geringem Zusatzkarbid-Anteil nicht nachstehen, bzw. diese und in vielen Fällen sogar übertreffen.The high proportion of a certain additional carbide to the tungsten carbide according to the invention in connection with a very specific binder alloy results not only in an abrupt increase in the corrosion resistance but also mechanical strength properties and wear properties which are not inferior to the known corrosion-resistant hard metal alloys with a low proportion of additional carbide, or these and in even exceed many cases.
Tabelle 1 zeigt die Gegenüberstellung der mechanischen Eigenschaften von Legierungen verschiedener Zusammensetzungen nach dem Stand der Technik und Legierungen verschiedener Zusammensetzungen nach der vorliegenden Erfindung. Aus der Tabelle ist insbesondere zu entnehmen, daß die meisten erfindungsgemäßen Legierungen im Vergleich zur Legierung 6, die hinsichtlich ihrer Korrosionsfestigkeit als beste Legierung nach dem Stand der Technik gilt, wesentlich bessere Werte in Härte und Biegebruchfestigkeit aufweisen.
Im folgenden ist die Erfindung anhand von Zeichnungen näher erläutert.The invention is explained in more detail below with reference to drawings.
Es zeigen:
Figur 1 ein Diagramm der Korrosionsbeständigkeit derLegierung 1, nach dem Stand der Technik, in verschiedenen korrosiven Medien, bei unterschiedlichen TemperaturenFigur 2 ein Diagramm der Korrosionsbeständigkeit derLegierung 6, nach dem Stand der Technik, in verschiedenen korrosiven Medien, bei unterschiedlichen TemperaturenFigur 3 ein Diagramm der Korrosionsbeständigkeit dererfindungsgemäßen Legierung 8 in verschiedenen korrosiven Medien, bei unterschiedlichen TemperaturenFigur 4 ein Diagramm der Korrosionsbeständigkeit dererfindungsgemäßen Legierung 8 in verdünnter Salzsäure (6N) bei 100°C, im Vergleich mit der Korrosionsbeständigkeit zweier Legierungen mit derselben Binderzusammensetzung, jedoch mit einem wesentlich geringeren Zusatzkarbidgehalt als bei der erfindungsgemäßen Legierung.Figur 5 ein Mikrofotografie des Gefüges derLegierung 1 nach dem Stand der Technik in 1 500-facher lichtmikroskopischer VergrößerungFigur 6 eine Mikrofotografie des Gefüges derLegierung 1 nach dem Stand der Technik in 1 500-facher rasterelektronenmikroskopischer VergrößerungFigur 7 eine Mikrofotografie des Gefüges dererfindungsgemäßen Legierung 8 in 1 500-facher lichtmikroskopischer VergrößerungFigur 8 eine Mikrofotografie des Gefüges dererfindungsgemäßen Legierung 8 in 1500-facher rasterelektronenmikroskopischer Vergrößerung
- 1 shows a diagram of the corrosion resistance of
alloy 1, according to the prior art, in different corrosive media, at different temperatures - Figure 2 is a diagram of the corrosion resistance of the
alloy 6, according to the prior art, in ver different corrosive media, at different temperatures - FIG. 3 shows a diagram of the corrosion resistance of the
alloy 8 according to the invention in different corrosive media, at different temperatures - FIG. 4 shows a diagram of the corrosion resistance of the
alloy 8 according to the invention in dilute hydrochloric acid (6N) at 100 ° C., in comparison with the corrosion resistance of two alloys with the same binder composition, but with a much lower additional carbide content than in the alloy according to the invention. - Figure 5 is a microphotograph of the structure of
alloy 1 according to the prior art in 1,500 times light microscopic magnification - Figure 6 is a microphotograph of the structure of
alloy 1 according to the prior art in 1,500 times scanning electron microscopic magnification - Figure 7 is a microphotograph of the structure of the
alloy 8 according to the invention in 1,500 times light microscopic magnification - FIG. 8 shows a microphotograph of the structure of the
alloy 8 according to the invention in a magnification of 1500 times by scanning electron microscopy
Der Vergleich der Legierungen mit einem niedrigen Gesamtanteil der Bindephase von 3 % (bekannte Legierung 1, erfindungsgemäße Legierungen 7, 8, 9,) zeigt durch die Figuren 1 und 3 beispielhaft, daß die Korrosionsfestigkeit der erfindungsgemäßen Legierungen in allen Medien um vieles besser ist, als bei der bekannten Legierung 1. In ihren Werten für Härte und Biegebruchfestigkeit liegen die erfindungsgemäßen Legierungen im Vergleich zur bekannten Legierung zum Großteil ebenfalls höher, wie aus Tabelle 1 zu entnehmen ist.The comparison of the alloys with a low total proportion of the binding phase of 3% (known
Die Vorteile der erfindungsgemäßen Legierung kommen insbesondere bei ihrer Verwendung als Werkstoff für Ventilteile bei Verbrennungskraftmaschinen und für verschleißfeste Teile im Chemieanlagenbau zum Tragen.The advantages of the alloy according to the invention are particularly evident when it is used as a material for valve parts in internal combustion engines and for wear-resistant parts in chemical plant construction.
Durch den hohen Zusatzkarbid-Anteil ist die erfindungsgemäße Legierung trotz niedrigen Bindemittelgehaltes mittels bekannter pulvermetallurgischer Verfahren problemlos herstellbar.Due to the high proportion of additional carbide, the alloy according to the invention can be produced without problems using known powder metallurgy processes, despite the low binder content.
Bei der Herstellung der Pulvermischungen können die Zusatzkarbide sowohl einzeln als auch in Form von Mischkarbid-Kristallen zugegeben werden. Genauso ist es möglich, das Wolframkarbid als Einzelkristall oder als Mischkristall mit einem Zusatzkarbid einzubringen.In the preparation of the powder mixtures, the additional carbides can be added either individually or in the form of mixed carbide crystals. It is also possible to introduce the tungsten carbide as a single crystal or as a mixed crystal with an additional carbide.
Durch eine spezielle Optimierung des pulvermetallurgischen Herstellungsverfahrens der erfindungsgemäßen Legierung können die vorteilhaften Eigenschaften noch weiter verbessert werden. Wesentlich bei diesem optimierten Herstellverfahren ist es, die Legierung bei möglichst tiefen Temperaturen während möglichst kurzer Zeiten zu sintern, wobei jedoch die Ausbildung einer Flüssigphase bei der Sinterung nicht verhindert werden darf. Die durch diese Art der Sinterung verbleibenden Restporositäten werden dann durch eine heißisostatische Nachverdichtung geschlossen. Durch dieses optimierte Herstellungsverfahren wird einerseits die gewünschte diskontinuierliche Teilung der Bindephase erreicht, anderseits kann dadurch das Kornwachstum der Karbidphase so gering wie möglich gehalten werden, was zu einer weiteren Härtesteigerung der erfindungsgemäßen Hartmetall-Legierung führt.The advantageous properties can be further improved by a special optimization of the powder metallurgical manufacturing process of the alloy according to the invention. It is essential in this optimized manufacturing process to sinter the alloy at the lowest possible temperatures for as short a time as possible, but the formation of a liquid phase during sintering must not be prevented. The residual porosities remaining through this type of sintering are then closed by hot isostatic post-compression. This optimized production process achieves the desired discontinuous division of the binder phase on the one hand, and on the other hand the grain growth of the carbide phase can be kept as low as possible, which leads to a further increase in hardness of the hard metal alloy according to the invention.
Die Herstellung der erfindungsgemäßen Legierung wird in den folgenden Beispielen näher erläutert, wobei die Endprodukte in diesen Beispielen einzelnen, der in Tabelle 1 aufgeführten Legierungen entsprechen.The preparation of the alloy according to the invention is explained in more detail in the following examples, the end products in these examples corresponding to individual alloys listed in Table 1.
Die Hartmetallegierung 8 wurde folgendermaßen hergestellt:
- Als Hartstoffkomponenten wurden 2 kg TaC-Pulver mit einem C. ges.-
Gehaltvon 6,22 % und einerKorngröße von Durchschnittslkorngröße von
- 2 kg of TaC powder with a C. total content of 6.22% and a grain size of 1.5 µm according to FSSS and 2.84 kg WC powder with an average grain size of 0.8 µm according to FSSS were used as hard material components. 0.025 kg Cr 3 C 2 , 0.05 kg Co and 0.075 kg Ni were used for the binder. The addition of carbon black was 0.007 kg.
Der Ansatz wurde 120 h in einer Kugelmühle in 2,5 I Aceton gemahlen. Nach der Trocknung des Ansatzpulvers wurden Formpreßlinge hergestellt, aus denen diverse Proben für Korrosionstests, Biegebruchfestigkeitstests u. ä. geformt wurden. Diese Proben wurden 40 Minuten bei 1450°C im Vakuum gesintert und anschließend heißisostatisch nachverdichtet.The mixture was ground in a ball mill in 2.5 l of acetone for 120 h. After the batch powder had been dried, molded articles were produced, from which various samples for corrosion tests, flexural strength tests and the like were produced. were formed. These samples were sintered in vacuo at 1450 ° C. for 40 minutes and subsequently hot isostatically compressed.
Claims (2)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT231585A AT385775B (en) | 1985-08-08 | 1985-08-08 | CORROSION-RESISTANT CARBIDE ALLOY |
| AT2315/85 | 1985-08-08 |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0214679A1 EP0214679A1 (en) | 1987-03-18 |
| EP0214679B1 EP0214679B1 (en) | 1988-12-21 |
| EP0214679B2 true EP0214679B2 (en) | 1993-03-24 |
Family
ID=3532086
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP19860201344 Expired - Lifetime EP0214679B2 (en) | 1985-08-08 | 1986-07-31 | Oxidation-resistant hard metal alloy |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0214679B2 (en) |
| AT (1) | AT385775B (en) |
| DE (1) | DE3661483D1 (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4963183A (en) * | 1989-03-03 | 1990-10-16 | Gte Valenite Corporation | Corrosion resistant cemented carbide |
| SE9100227D0 (en) | 1991-01-25 | 1991-01-25 | Sandvik Ab | CORROSION RESISTANT CEMENTED CARBIDE |
| US5925197A (en) * | 1992-01-24 | 1999-07-20 | Sandvik Ab | Hard alloys for tools in the wood industry |
| US6037287A (en) * | 1997-11-26 | 2000-03-14 | Praxair S.T. Technology, Inc. | Laser clad pot roll sleeves and bushings for galvanizing baths |
| SE511212C2 (en) * | 1997-12-22 | 1999-08-23 | Sandvik Ab | Ballpoint pens and their use for ballpoint pens with water-based ink |
| US6521353B1 (en) | 1999-08-23 | 2003-02-18 | Kennametal Pc Inc. | Low thermal conductivity hard metal |
| JP2001179507A (en) * | 1999-12-24 | 2001-07-03 | Kyocera Corp | Cutting tool |
| DE10135790B4 (en) * | 2001-07-23 | 2005-07-14 | Kennametal Inc. | Fine grained cemented carbide and its use |
| CN100420762C (en) * | 2006-04-28 | 2008-09-24 | 自贡硬质合金有限责任公司 | TiC-WC based alloy products |
| CN104755446B (en) * | 2012-10-09 | 2016-11-16 | 山特维克知识产权股份有限公司 | The wear-resisting hard metal of low binding agent |
| JP7272353B2 (en) * | 2018-11-01 | 2023-05-12 | 住友電気工業株式会社 | Cemented Carbide, Cutting Tool and Cemented Carbide Manufacturing Method |
| GB201820632D0 (en) * | 2018-12-18 | 2019-01-30 | Sandvik Hyperion AB | Cemented carbide for high demand applications |
| DE102019110950A1 (en) | 2019-04-29 | 2020-10-29 | Kennametal Inc. | Hard metal compositions and their applications |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2607676A (en) * | 1949-06-01 | 1952-08-19 | Kurtz Jacob | Hard metal compositions |
| US3215510A (en) * | 1963-10-02 | 1965-11-02 | Gen Electric | Alloy |
| US3455682A (en) * | 1967-07-31 | 1969-07-15 | Du Pont | Isostatic hot pressing of refractory bodies |
| SE333437B (en) * | 1969-03-03 | 1971-03-15 | Asea Ab | |
| US3628921A (en) * | 1969-08-18 | 1971-12-21 | Parker Pen Co | Corrosion resistant binder for tungsten carbide materials and titanium carbide materials |
| SE420844B (en) * | 1979-05-17 | 1981-11-02 | Sandvik Ab | SINTRAD HARD METAL OF NICKEL-BASED BINDING METAL AND VOLFORCARBID |
| CH653204GA3 (en) * | 1983-03-15 | 1985-12-31 |
-
1985
- 1985-08-08 AT AT231585A patent/AT385775B/en active
-
1986
- 1986-07-31 DE DE8686201344T patent/DE3661483D1/en not_active Expired
- 1986-07-31 EP EP19860201344 patent/EP0214679B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0214679A1 (en) | 1987-03-18 |
| AT385775B (en) | 1988-05-10 |
| DE3661483D1 (en) | 1989-01-26 |
| EP0214679B1 (en) | 1988-12-21 |
| ATA231585A (en) | 1987-10-15 |
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