EP0512633A2 - Method for aftertreating the focal track of rotary anodes of X-ray tubes - Google Patents
Method for aftertreating the focal track of rotary anodes of X-ray tubes Download PDFInfo
- Publication number
- EP0512633A2 EP0512633A2 EP92201234A EP92201234A EP0512633A2 EP 0512633 A2 EP0512633 A2 EP 0512633A2 EP 92201234 A EP92201234 A EP 92201234A EP 92201234 A EP92201234 A EP 92201234A EP 0512633 A2 EP0512633 A2 EP 0512633A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- ray
- producing
- melting
- rotary anode
- focal track
- 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.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
- H01J9/02—Manufacture of electrodes or electrode systems
- H01J9/14—Manufacture of electrodes or electrode systems of non-emitting electrodes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J35/00—X-ray tubes
- H01J35/02—Details
- H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
- H01J35/08—Anodes; Anti cathodes
- H01J35/10—Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2235/00—X-ray tubes
- H01J2235/08—Targets (anodes) and X-ray converters
- H01J2235/085—Target treatment, e.g. ageing, heating
Definitions
- the invention relates to a method for producing an X-ray rotary anode with an annular focal path region made of refractory metals, e.g. by powder metallurgy or CVD or PVD methods. Tungsten or tungsten rhenium.
- X-ray rotary anodes Today, high-melting metals or graphite, or a combination of both materials, are used as the base material for X-ray rotary anodes.
- the actual generation area of the X-rays, the focal path area consists of tungsten, molybdenum or their alloys.
- Metallic X-ray rotary anodes are manufactured according to sintered metallurgical processes for reasons of shape, the materials used and the required properties; the focal path area itself is produced using sintered metallurgical processes or more recently also using CVD or PVD coating processes.
- Such rotating anodes or focal path areas have a residual porosity in the range of 0.1-10% in the finished state, measured on the theoretical density.
- Such an X-ray rotating anode is described in EP-A1-0 116 385, with the rotating anode optionally being post-treated and heat-treated after the focal path layer has been applied in accordance with the process there.
- This residual porosity has a number of disruptive disadvantages for the operation of X-ray rotary anodes, which is generally carried out in a high vacuum.
- the porosity causes the release of gases trapped in the pores. This in turn leads to gas discharges in the high vacuum of the tube with undesirable tube short circuits, which in turn cause anode melting.
- the thermal conductivity that is so important for the resilience of X-ray tubes decreases about with the square of the porosity.
- Porosity of the focal track surface causes increased surface roughness and reduces the X-ray yield due to self-absorption.
- a porous surface also means the risk of particle breakouts from the surface, which significantly increases the negative effects of gas leaks.
- the mechanical bonding of the individual crystallites in the structure depends on the porosity, but also on the metallurgical conditions at the grain boundaries, in particular on impurities at the grain boundaries. In the course of powder metallurgical manufacturing processes, however, a concentration of impurities that are insoluble in the metal at the grain boundaries is unavoidable; this means another disruptive factor when operating X-ray rotary anodes.
- Focal path linings produced by sinter metallurgical processes in particular made of tungsten-rhenium, occasionally show a brittle, intermetallic tungsten-rhenium phase, the so-called sigma phase, which is due to inhomogeneities due to inadequate mixing of the individual alloy components in the powder batch.
- the inevitable thermal shock loading of rotating anodes during operation then leads, particularly in these and in the areas emanating from them, to highly undesirable crack formation, with a reduction in the X-ray yield in the focal path area as a result.
- the object of the present invention is then the elimination, or at least a substantial reduction of the aforementioned disadvantages.
- the task is to reduce the porosity and impurities, especially at the grain boundaries in the focal path area.
- the previous manufacturing processes prowder metallurgy and CVD or PVD processes
- the object is achieved according to the invention by a method according to which the focal path region of an X-ray rotary anode is aftertreated at a depth of less than 1.5 mm by means of local, superficial melting.
- the inventive aftertreatment by means of superficial melting is carried out in accordance with a method which has been tried and tested in practice by the action of focused beams of high-energy electrons or photons on the surface of the focal path area of X-ray rotary anodes down to a certain depth of action.
- a changed metallic structure is formed in this area, the porosity and the proportion of impurities, in particular in the grain boundary area, are significantly reduced.
- the grain structure remains comparatively fine in contrast to conventional melt metallurgical processes.
- the grain size that can be achieved corresponds to that which is customary in powder metallurgy or by means of application methods of the focal track areas.
- the melting can be carried out once or several times in succession and influences the metallic structure of the focal track area that can be achieved in the final state. With the removal of the residual porosity, the disturbances in the operation of x-ray rotary anodes shown at the beginning also disappear.
- Suitable focusable energy sources for the melting process are the laser, devices for generating particle beams, in particular electron beams, and highly focusable high-power lamps.
- the material-related degree of conversion of radiated energy / heat is important for the energy source selected in the individual case.
- the equipment complexity and the processing e.g. B. Treatment under protective gas or in a high vacuum, a role. Due to the high reflectivity of refractory metals for electromagnetic waves in the spectral range 0.3 - 20 ⁇ m (> 80%), the use of electron beams with an efficiency of ⁇ 60% usually offers advantages.
- the desired melting depth according to the inventive method is to be dimensioned to match the thermomechanical loads to be expected in the combustion path area during operation.
- a melting depth between 0.05 and 1.5 mm has proven to be useful. In the majority of applications, a melting depth between 0.5 and 0.8 mm offers the best cost-benefit ratio.
- the process of melting and rapid cooling results in the structure states being amorphous, very fine-grained isotropic, finely grained or coarse-crystalline.
- the resulting stresses in the structure can be reduced by a subsequent vacuum annealing in the range 900 - 1600 o C.
- the melting process leads to a very smooth surface with a low surface roughness in the focal path area. Nevertheless, due to the extremely high demands on the surface smoothness of X-ray rotary anodes in the focal path area, it is generally unavoidable to grind the surface after the melting process.
- a rotating anode base body with a tungsten / rhenium focal track area which is manufactured in the usual powder metallurgical way, is - like later in operation - mounted on a rotating holding shaft and inserted into a piston that can be evacuated to high vacuum.
- the rotating anode focal path area is arranged opposite a focussing glow emission cathode.
- the slowly rotating rotating anode is brought uniformly to approx. 800 o C by means of a defocused electron beam.
- the rotating anode is degassed, which means that foreign atoms and insufficiently adhering material particles are removed from the surface.
- the electron beam is then brought to a line focus of 20 mm in length and 2 mm in width and to a power of 6 kW, and the rotating anode rotating at 3-6 revolutions per minute is melted on the surface in three successive revolutions.
- the melt which is horizontal due to the arrangement, solidifies during the subsequent cooling process so smoothly that even with subsequent removal of 0.2-0.3 mm a smooth burn sheet surface that meets the requirements is achieved by grinding.
- the structure of a focal path region melted in this way has directionally solidified crystallites with an average diameter of 150 ⁇ m. It shows no pores and provides reliable information for an excellent bond between the individual grains or crystallites.
- An X-ray rotary anode manufactured according to the present invention was compared with a rotary anode manufactured according to the prior art.
- a so-called tube test bench in which the load on the X-ray rotating anode can be simulated completely identically to that in later operation, both comparison rotating anodes were tested with the following loading cycles: Electron beam power 60 kW, focus 12 x 1.8 mm2, irradiation cycle 7 x 0.1 S with 0.1 S pause each (corresponds to an X-ray image) and 59 S cooling, total number of images 1200.
- the two comparative rotating anodes were checked for their superficial structural changes both under a scanning electron microscope and measured for surface roughness using the stylus.
- the roughening of the rotating anode according to the present invention as a result of material fatigue was not only less, but, based on the entire surface area of the focal path, was more uniform than with the rotating anode according to the prior art. Accordingly, the x-ray rotating anode according to the invention showed a more uniform and less dense crack network with smaller crack widths than the comparison anode according to the prior art.
- the rotating anode according to the invention has a very high vacuum stability.
Abstract
Description
Die Erfindung betrifft ein Verfahren zur Herstellung einer Röntgendrehanode mit einem auf pulvermetallurgischem Wege oder mittels CVD- oder PVD-Verfahren gefertigten ringförmigen Brennbahnbereich aus hochschmelzenden Metallen, z.B. Wolfram bzw. Wolfram-Rhenium.The invention relates to a method for producing an X-ray rotary anode with an annular focal path region made of refractory metals, e.g. by powder metallurgy or CVD or PVD methods. Tungsten or tungsten rhenium.
Als Basiswerkstoff für Röntgendrehanoden werden heute hochschmelzende Metalle oder Graphit, bzw. ein Verbund beider Materialien verwendet. Der eigentliche Erzeugungsbereich der Röntgenstrahlung, der Brennbahnbereich, besteht aus Wolfram, Molybdän oder deren Legierungen.
Metallische Röntgendrehanoden werden aus Gründen der Form, der verwendeten Werkstoffe sowie der geforderten Eigenschaften nach sintermetallurgischen Verfahren hergestellt; der Brennbahnbereich selbst wird nach sintermetallurgischen Verfahren oder neuerdings vermehrt auch mittels CVD- oder PVD-Beschichtungsverfahren erzeugt. Derartige Drehanoden bzw. Brennbahnbereiche besitzen eine Restporosität im Bereich von 0,1 - 10 % im endgefertigten Zustand, gemessen an der theoretischen Dichte.
Eine derartige Röntgendrehanode ist in der EP-A1-0 116 385 beschrieben, wobei gemäß dem dortigen Verfahren die Drehanode nach Aufbringen der Brennbahnschicht wahlweise nach- und wärmebehandelt wird.Today, high-melting metals or graphite, or a combination of both materials, are used as the base material for X-ray rotary anodes. The actual generation area of the X-rays, the focal path area, consists of tungsten, molybdenum or their alloys.
Metallic X-ray rotary anodes are manufactured according to sintered metallurgical processes for reasons of shape, the materials used and the required properties; the focal path area itself is produced using sintered metallurgical processes or more recently also using CVD or PVD coating processes. Such rotating anodes or focal path areas have a residual porosity in the range of 0.1-10% in the finished state, measured on the theoretical density.
Such an X-ray rotating anode is described in EP-A1-0 116 385, with the rotating anode optionally being post-treated and heat-treated after the focal path layer has been applied in accordance with the process there.
Diese Restporosität hat für den Betrieb von Röntgendrehanoden, der grundsätzlich im Hochvakuum erfolgt, eine Reihe von störenden Nachteilen. Die Porosität verursacht die Abgabe von in den Poren eingeschlossenen Gasen. Das wiederum führt zu Gasentladungen im Hochvakuum der Röhre mit unerwünschten Röhrenkurzschlüssen, die ihrerseits Anodenanschmelzungen verursachen. Die für eine Belastbarkeit von Röntgenröhren so wichtige Wärmeleitfähigkeit nimmt etwa mit dem Quadrat der Porosität ab. Porosität der Brennbahnoberfläche bedingt erhöhte Oberflächenrauhigkeit und vermindert die Röntgenstrahlenausbeute wegen Selbstabsorption. Poröse Oberfläche bedeutet aber auch die Gefahr von Partikelausbrüchen aus der Oberfläche, was die negativen Auswirkungen von Gasaustritten noch wesentlich verstärkt.This residual porosity has a number of disruptive disadvantages for the operation of X-ray rotary anodes, which is generally carried out in a high vacuum. The porosity causes the release of gases trapped in the pores. This in turn leads to gas discharges in the high vacuum of the tube with undesirable tube short circuits, which in turn cause anode melting. The thermal conductivity that is so important for the resilience of X-ray tubes decreases about with the square of the porosity. Porosity of the focal track surface causes increased surface roughness and reduces the X-ray yield due to self-absorption. A porous surface also means the risk of particle breakouts from the surface, which significantly increases the negative effects of gas leaks.
Die mechanische Bindung der einzelnen Kristallite im Gefüge ist von der Porosität, aber auch von den metallurgischen Zuständen an den Korngrenzen, insbesondere von Verunreinigungen an den Korngrenzen abhängig. Im Zuge pulvermetallurgischer Herstellungsverfahren ist aber eine Konzentration von im Metall unlösbaren Verunreinigungen an den Korngrenzen unumgänglich; dies bedeutet einen weiteren Störfaktor beim Betrieb von Röntgendrehanoden.The mechanical bonding of the individual crystallites in the structure depends on the porosity, but also on the metallurgical conditions at the grain boundaries, in particular on impurities at the grain boundaries. In the course of powder metallurgical manufacturing processes, however, a concentration of impurities that are insoluble in the metal at the grain boundaries is unavoidable; this means another disruptive factor when operating X-ray rotary anodes.
Nach sintermetallurgischen Verfahren hergestellte Brennbahnbeläge, insbesondere aus Wolfram-Rhenium, weisen fallweise lokal eine spröde, intermetallische Wolfram-Rhenium-Phase, die sogenannte Sigmaphase auf, die auf Inhomogenitäten durch unzureichendes Vermischen der einzelnen Legierungsanteile im Pulveransatz zurückzuführen ist. Die unvermeidliche Thermoschockbelastung von Drehanoden im Betrieb führt dann insbesondere in diesen, und in von diesen ausgehenden Bereichen, zu höchst unerwünschter Rißbildung, mit einer Verminderung der Röntgenstrahlenausbeute im Brennbahnbereich als Folge.Focal path linings produced by sinter metallurgical processes, in particular made of tungsten-rhenium, occasionally show a brittle, intermetallic tungsten-rhenium phase, the so-called sigma phase, which is due to inhomogeneities due to inadequate mixing of the individual alloy components in the powder batch. The inevitable thermal shock loading of rotating anodes during operation then leads, particularly in these and in the areas emanating from them, to highly undesirable crack formation, with a reduction in the X-ray yield in the focal path area as a result.
Die vorbeschriebenen, unterschiedlich häufig auftretenden Störungen begrenzen die Lebensdauer und führen in Einzelfällen zu vorzeitigem Ausfall der Röntgendrehanoden.The above-described malfunctions, which occur with different frequencies, limit the lifespan and in individual cases lead to premature failure of the X-ray rotary anodes.
Aufgabe vorliegender Erfindung ist danach die Beseitigung, oder doch eine wesentliche Herabsetzung der vorgenannten Nachteile. Aufgabe ist insbesondere die Verringerung der Porosität und der Verunreinigungen, insbesondere an den Korngrenzen im Brennbahnbereich. Die bisherigen Herstellverfahren (Pulvermetallurgie und CVD- bzw. PVD-Verfahren) sollen wegen deren Wirtschaftlichkeit und der daraus resultierenden guten Werkstoffeigenschaften beibehalten werden.The object of the present invention is then the elimination, or at least a substantial reduction of the aforementioned disadvantages. In particular, the task is to reduce the porosity and impurities, especially at the grain boundaries in the focal path area. The previous manufacturing processes (powder metallurgy and CVD or PVD processes) should be retained because of their economy and the resulting good material properties.
Die Aufgabe wird erfindungsgemäß durch ein Verfahren gelöst, nach dem der Brennbahnbereich einer Röntgendrehanode in einer Tiefe kleiner 1,5 mm mittels lokaler, oberflächlicher Aufschmelzung nachbehandelt wird.The object is achieved according to the invention by a method according to which the focal path region of an X-ray rotary anode is aftertreated at a depth of less than 1.5 mm by means of local, superficial melting.
Die erfinderische Nachbehandlung mittels oberflächlicher Aufschmelzung erfolgt entsprechend einem in Praxis bewährten Verfahren durch Einwirken gebündelter Strahlen von hochenergetischen Elektronen oder Photonen auf die Oberfläche des Brennbahnbereiches von Röntgendrehanoden bis in eine bestimmte Einwirktiefe. Mit dem Aufschmelzen bildet sich in diesem Bereich ein verändertes metallisches Gefüge, die Porosität und der Anteil an Verunreinigungen, insbesondere im Korngrenzenbereich, werden ganz wesentlich gesenkt. Wegen des sehr lokalen Aufschmelzens und sehr raschen Abkühlens nach dem Aufschmelzen bleibt im Unterschied zu üblichen schmelzmetallurgischen Verfahren das Korngefüge vergleichsweise fein. Die erreichbare Korngröße entspricht derjenigen, wie sie in pulvermetallurgisch oder mittels Auftragverfahren hergestellten Brennbahnbereichen üblich ist.The inventive aftertreatment by means of superficial melting is carried out in accordance with a method which has been tried and tested in practice by the action of focused beams of high-energy electrons or photons on the surface of the focal path area of X-ray rotary anodes down to a certain depth of action. With the melting, a changed metallic structure is formed in this area, the porosity and the proportion of impurities, in particular in the grain boundary area, are significantly reduced. Because of the very local melting and very rapid cooling after melting, the grain structure remains comparatively fine in contrast to conventional melt metallurgical processes. The grain size that can be achieved corresponds to that which is customary in powder metallurgy or by means of application methods of the focal track areas.
Das Aufschmelzen kann ein einziges Mal oder auch mehrmals hintereinander erfolgen und beeinflußt die im Endzustand erzielbare metallische Struktur des Brennbahnbereiches. Mit der Beseitigung der Restporosität verschwinden auch die eingangs aufgezeigten bisherigen Störungen beim Betrieb von Röntgendrehanoden.The melting can be carried out once or several times in succession and influences the metallic structure of the focal track area that can be achieved in the final state. With the removal of the residual porosity, the disturbances in the operation of x-ray rotary anodes shown at the beginning also disappear.
Als geeignete fokussierbare Energiequellen für den Aufschmelzprozeß kommen der Laser, Geräte zur Erzeugung von Teilchenstrahlen, insbesondere Elektronenstrahlen, sowie hochfokussierbare Hochleistungslampen in Betracht. Für die im Einzelfall gewählte Energiequelle ist der werkstoffbedingte Umwandlungsgrad eingestrahlte Energie/Wärme von Bedeutung. Weiters spielen der apparative Aufwand und die Verfahrensabwicklung, z. B. Behandlung unter Schutzgas oder im Hochvakuum, eine Rolle. Wegen des hohen Reflexionsvermögens hochschmelzender Metalle für elektromagnetische Wellen im Spektralbereich 0,3 - 20 µm ( > 80 %) bietet der Einsatz von Elektronenstrahlen mit einem Wirkungsgrad ≧ 60 % in der Regel Vorteile.Suitable focusable energy sources for the melting process are the laser, devices for generating particle beams, in particular electron beams, and highly focusable high-power lamps. The material-related degree of conversion of radiated energy / heat is important for the energy source selected in the individual case. Furthermore, the equipment complexity and the processing, e.g. B. Treatment under protective gas or in a high vacuum, a role. Due to the high reflectivity of refractory metals for electromagnetic waves in the spectral range 0.3 - 20 µm (> 80%), the use of electron beams with an efficiency of ≧ 60% usually offers advantages.
Die anzustrebende Aufschmelztiefe gemäß erfinderichem Verfahren ist auf die im Betrieb zu erwartenden, thermomechanischen Belastungen des Brennbahnbereiches abgestimmt zu bemessen. Eine Aufschmelztiefe zwischen 0,05 und 1,5 mm hat sich als brauchbar erwiesen. In der überwiegenden Zahl der Anwendungsfälle bietet eine Aufschmelztiefe zwischen 0,5 und 0,8 mm das beste Kosten-/Nutzenverhältnis.The desired melting depth according to the inventive method is to be dimensioned to match the thermomechanical loads to be expected in the combustion path area during operation. A melting depth between 0.05 and 1.5 mm has proven to be useful. In the majority of applications, a melting depth between 0.5 and 0.8 mm offers the best cost-benefit ratio.
Der Prozeß des Aufschmelzens und raschen Abkühlens ergibt je nach Prozeßführung die Gefügezustände amorph, sehr feinkörnig isotrop, feinstengelig oder grobkristallin. Dabei auftretende Spannungen im Gefüge können durch eine nachgeschaltete Vakuumglühung im Bereich 900 - 1600oC abgebaut werden.The process of melting and rapid cooling, depending on the process control, results in the structure states being amorphous, very fine-grained isotropic, finely grained or coarse-crystalline. The resulting stresses in the structure can be reduced by a subsequent vacuum annealing in the range 900 - 1600 o C.
Der Aufschmelzprozeß führt im Brennbahnbereich zu einer sehr glatten Oberfläche von geringer Oberflächenrauhtiefe. Dennoch ist es aufgrund der extrem hohen Anforderungen an die Oberflächenglattheit von Röntgendrehanoden im Brennbahnbereich in der Regel unumgänglich, die Oberfläche nach dem Aufschmelzungsprozeß zu überschleifen.The melting process leads to a very smooth surface with a low surface roughness in the focal path area. Nevertheless, due to the extremely high demands on the surface smoothness of X-ray rotary anodes in the focal path area, it is generally unavoidable to grind the surface after the melting process.
Das erfindungsgemäße Verfahren wird anhand eines Beispieles näher beschrieben. Ein auf üblichem pulvermetallurgischem Wege hergestellter Drehanoden-Grundkörper mit Wolfram/Rhenium-Brennbahnbereich wird - so wie auch später im Betrieb - auf eine rotierende Haltewelle montiert und in einen auf Hochvakuum evakuierbaren Kolben eingesetzt. Der Drehanoden-Brennbahnbereich wird dabei gegenüber einer fokusierenden Glühemissionskathode angeordnet. Zunächst wird die langsam rotierende Drehanode mittels eines defokussierten Elektronenstrahles einheitlich auf ca. 800oC gebracht. Dabei wird die Drehanode entgast, das heißt, es werden Fremdatome und nicht ausreichend haftende Materialteilchen von der Oberfläche entfernt. Dann wird der Elektronenstrahl auf einen Strichfokus von 20 mm Länge und 2 mm Breite sowie auf eine Leistung von 6 kW gebracht und es wird die mit 3-6 Umdrehungen pro Minute rotierende Drehanode in drei aufeinanderfolgenden Umläufen oberflächlich aufgeschmolzen. Dabei entsteht eine Schmelzzone von ca. 17 mm Breite und 0,7 mm mittlerer Tiefe. Die aufgrund der Anordnung jeweils horizontal liegende Schmelze erstarrt beim anschließenden Abkühlen so glatt, daß bereits bei einer anschließenden Abtragung von 0,2 - 0,3 mm durch Überschleifen eine anforderungsgerechte, glatte Brennbahnbelagsoberfläche erzielt wird.The method according to the invention is described in more detail using an example. A rotating anode base body with a tungsten / rhenium focal track area, which is manufactured in the usual powder metallurgical way, is - like later in operation - mounted on a rotating holding shaft and inserted into a piston that can be evacuated to high vacuum. The rotating anode focal path area is arranged opposite a focussing glow emission cathode. First, the slowly rotating rotating anode is brought uniformly to approx. 800 o C by means of a defocused electron beam. The rotating anode is degassed, which means that foreign atoms and insufficiently adhering material particles are removed from the surface. The electron beam is then brought to a line focus of 20 mm in length and 2 mm in width and to a power of 6 kW, and the rotating anode rotating at 3-6 revolutions per minute is melted on the surface in three successive revolutions. This creates a melting zone of approx. 17 mm wide and 0.7 mm medium depth. The melt, which is horizontal due to the arrangement, solidifies during the subsequent cooling process so smoothly that even with subsequent removal of 0.2-0.3 mm a smooth burn sheet surface that meets the requirements is achieved by grinding.
Das Gefüge eines derart aufgeschmolzenen Brennbahnbereiches weist gerichtet erstarrte Kristallite eines mittleren Durchmessers von 150 µm auf. Es zeigt keinerlei Poren und gibt zuverlässige Hinweise für eine ausgezeichnete Bindung der einzelnen Körner bzw. Kristallite aneinander.The structure of a focal path region melted in this way has directionally solidified crystallites with an average diameter of 150 μm. It shows no pores and provides reliable information for an excellent bond between the individual grains or crystallites.
Eine gemäß vorliegender Erfindung hergestellte Röntgendrehanode wurde mit einer nach dem Stand der Technik gefertigten Drehanode verglichen. In einem sogenannten Röhrenprüfstand, in dem die Belastung der Röntgendrehanode derjenigen im späteren Betrieb völlig identisch simuliert werden kann, wurden beide Vergleichsdrehanoden mit folgenden Belastungszyklen getestet:
Elektronenstrahlleistung 60 kW, Fokus 12 x 1,8 mm², Bestrahlungszyklus 7 x 0,1 S mit jeweils 0,1 S Pause (entspricht einer Röntgenaufnahme) und 59 S Abkühlung, gesamte Aufnahmenzahl 1200.
Nach Beendigung dieses Tests wurden die beiden Vergleichsdrehanoden hinsichtlich ihrer oberflächlichen Strukturänderungen sowohl im Rasterelektronenmikroskop geprüft, als auch mittels des Abtaststiftes auf Oberflächenrauhigkeit vermessen.
Die mittlere Rauhtiefe Ra bei der Drehanode gemäß Stand der Technik betrug Ra = 5,5 µm, die Drehanode gemäß vorliegender Erfindung hatte eine mittlere Rauhtiefe von Ra = 3,5 µm. Die Aufrauhung der Drehanode gemäß vorliegender Erfindung infolge Materialermüdung war nicht nur geringer, sondern, bezogen auf den gesamten Brennbahnoberflächenbereich, gleichmäßiger als bei der Drehanode gemäß Stand der Technik. Entsprechend zeigte die erfindungsgemäße Röntgendrehanode ein gleichmäßigeres und weniger dichtes Rißnetzwerk mit geringeren Rißbreiten als die Vergleichsanode gemäß Stand der Technik. Die erfindungsgemäße Drehanode weist eine sehr hohe Vakuumstabilität auf. Dadurch läßt sich die sogenannte Einlaufphase deutlich verkürzen, in welcher eine Drehanode in der Röhre unter dem Elektronenstrahl bei fortlaufendem Abpumpen von austretenden Restgasen erwärmt und erstmals auf Betriebsbedingungen gebracht wird. Die elektrische Stabilität der Drehanode im Betrieb war einwandfrei.
Die bei Testende gemessene Röntgenstrahlendosis pro Aufnahme lag bei der gemäß Erfindung hergestellten Drehanode um 20 % höher als bei der Vergleichsanode nach dem Stand der Technik.
Die Lebenserwartung der Röntgendrehanode lag aufgrund der vorgenannten Qualitätsverbesserungen somit deutlich höher als die der Vergleichsanode.An X-ray rotary anode manufactured according to the present invention was compared with a rotary anode manufactured according to the prior art. In a so-called tube test bench, in which the load on the X-ray rotating anode can be simulated completely identically to that in later operation, both comparison rotating anodes were tested with the following loading cycles:
Electron beam power 60 kW, focus 12 x 1.8 mm², irradiation cycle 7 x 0.1 S with 0.1 S pause each (corresponds to an X-ray image) and 59 S cooling, total number of images 1200.
After completion of this test, the two comparative rotating anodes were checked for their superficial structural changes both under a scanning electron microscope and measured for surface roughness using the stylus.
The average roughness depth R a in the rotating anode according to the prior art was R a = 5.5 μm, the rotating anode according to the present invention had an average roughness depth of R a = 3.5 μm. The roughening of the rotating anode according to the present invention as a result of material fatigue was not only less, but, based on the entire surface area of the focal path, was more uniform than with the rotating anode according to the prior art. Accordingly, the x-ray rotating anode according to the invention showed a more uniform and less dense crack network with smaller crack widths than the comparison anode according to the prior art. The rotating anode according to the invention has a very high vacuum stability. This significantly shortens the so-called running-in phase, in which a rotating anode in the tube is heated under the electron beam with continuous evacuation of escaping residual gases and brought to operating conditions for the first time. The electrical stability of the rotating anode in operation was flawless.
The X-ray dose per exposure measured at the end of the test was 20% higher in the rotary anode produced according to the invention than in the comparison anode according to the prior art.
The life expectancy of the x-ray rotary anode was therefore significantly higher than that of the comparison anode due to the aforementioned quality improvements.
Claims (9)
daß der Brennbahnbereich in einer Tiefe von kleiner 1,5 mm mittels lokaler, oberflächlicher Aufschmelzung nachbehandelt wird.Process for producing an X-ray rotary anode with an annular focal track region made of high-melting metals, which is produced by powder metallurgy or by means of CVD or PVD processes, characterized in that
that the focal path area is treated at a depth of less than 1.5 mm by means of local, superficial melting.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT947/91 | 1991-05-07 | ||
| AT0094791A AT397005B (en) | 1991-05-07 | 1991-05-07 | METHOD FOR PRODUCING AN X-RAY ROTARY ANODE |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0512633A2 true EP0512633A2 (en) | 1992-11-11 |
| EP0512633A3 EP0512633A3 (en) | 1993-02-17 |
| EP0512633B1 EP0512633B1 (en) | 1994-07-20 |
Family
ID=3503501
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP92201234A Expired - Lifetime EP0512633B1 (en) | 1991-05-07 | 1992-05-04 | Method for aftertreating the focal track of rotary anodes of X-ray tubes |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0512633B1 (en) |
| JP (1) | JP3345439B2 (en) |
| AT (2) | AT397005B (en) |
| DE (1) | DE59200292D1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009146986A1 (en) * | 2008-06-05 | 2009-12-10 | H.C. Starck Gmbh | Process for producing pure ammonium perrhenate |
| DE102012217194A1 (en) | 2012-09-24 | 2014-03-27 | Siemens Aktiengesellschaft | Producing a refractory metal component |
| EP3840009A1 (en) * | 2019-12-20 | 2021-06-23 | Varex Imaging Corporation | Aligned grain structure targets, systems, and methods of forming |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD109768A1 (en) * | 1974-01-10 | 1974-11-12 | ||
| EP0116385A1 (en) * | 1983-01-25 | 1984-08-22 | Koninklijke Philips Electronics N.V. | Method of manufacturing a rotary anode for X-ray tubes and anode thus produced |
-
1991
- 1991-05-07 AT AT0094791A patent/AT397005B/en not_active IP Right Cessation
-
1992
- 1992-05-01 JP JP13969692A patent/JP3345439B2/en not_active Ceased
- 1992-05-04 DE DE59200292T patent/DE59200292D1/en not_active Expired - Fee Related
- 1992-05-04 EP EP92201234A patent/EP0512633B1/en not_active Expired - Lifetime
- 1992-05-04 AT AT92201234T patent/ATE108948T1/en not_active IP Right Cessation
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD109768A1 (en) * | 1974-01-10 | 1974-11-12 | ||
| EP0116385A1 (en) * | 1983-01-25 | 1984-08-22 | Koninklijke Philips Electronics N.V. | Method of manufacturing a rotary anode for X-ray tubes and anode thus produced |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009146986A1 (en) * | 2008-06-05 | 2009-12-10 | H.C. Starck Gmbh | Process for producing pure ammonium perrhenate |
| US8795509B2 (en) | 2008-06-05 | 2014-08-05 | H. C. Starch GmbH | Process for producing pure ammonium perrhenate |
| DE102012217194A1 (en) | 2012-09-24 | 2014-03-27 | Siemens Aktiengesellschaft | Producing a refractory metal component |
| WO2014044431A1 (en) | 2012-09-24 | 2014-03-27 | Siemens Aktiengesellschaft | Production of a refractory metal component |
| EP3840009A1 (en) * | 2019-12-20 | 2021-06-23 | Varex Imaging Corporation | Aligned grain structure targets, systems, and methods of forming |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0512633A3 (en) | 1993-02-17 |
| AT397005B (en) | 1994-01-25 |
| EP0512633B1 (en) | 1994-07-20 |
| ATA94791A (en) | 1993-05-15 |
| DE59200292D1 (en) | 1994-08-25 |
| JPH05151891A (en) | 1993-06-18 |
| JP3345439B2 (en) | 2002-11-18 |
| ATE108948T1 (en) | 1994-08-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| AT502265B1 (en) | X-RAY SOUND ARGETS OF MOLYBDENAL REINFORCEMENT REINFORCED WITH A HIGHLY RESISTANT OXIDE DISPERSION | |
| EP2193538B1 (en) | X-ray anode having improved heat dissipation | |
| AT504405B1 (en) | METHOD FOR MANUFACTURING AN X-RAY GIFT ARGET | |
| AT12494U9 (en) | X ROTARY ANODE | |
| CH635704A5 (en) | X-ray tube-ANODE AND METHOD FOR PRODUCING. | |
| DE2154888A1 (en) | ROENTINE PIPE | |
| DE1952854A1 (en) | Process for converting the grain structure of metal surfaces and X-ray targets | |
| EP0143222A1 (en) | Thermionic cathode capable of high emission for an electron tube, and method of manufacture | |
| AT397005B (en) | METHOD FOR PRODUCING AN X-RAY ROTARY ANODE | |
| EP0874385B1 (en) | Method of manufacturing an anode for x-ray tubes | |
| US3328626A (en) | Rotary anodes of x-ray tubes | |
| JPS59141144A (en) | Method of producing x-ray tube rotary anode and rotary anode | |
| CA1081758A (en) | X-ray tube anode with alloyed surface and method of making the same | |
| KR101080713B1 (en) | Molybdenum alloy x-ray targets having uniform grain structure | |
| US5246742A (en) | Method of posttreating the focal track of X-ray rotary anodes | |
| DE2146918B2 (en) | Rotating anode for X=ray tube with refractory coating - of graphite applied by pyrolytic deposition | |
| DE102012217194A1 (en) | Producing a refractory metal component | |
| NL8402828A (en) | METHOD FOR MANUFACTURING A ROTARY TURNAROUND AND ROTARY TURNAROOD MANUFACTURED BY THE METHOD | |
| DE102019120570A1 (en) | PROCESS AND ELECTRON BEAM SYSTEM FOR THE PROCESSING OF POWDERED MATERIALS AT HIGH ACCELERATION VOLTAGES | |
| CH616528A5 (en) | ||
| DE102012210506B3 (en) | Manufacturing rotary anode for x-ray tube, comprises providing base body made of ceramics based on silicon carbide, and depositing tungsten focal track on predetermined region of base body by electron beam deposition welding | |
| DE3236104A1 (en) | HIGH-PERFORMANCE X-RAY ANODE AND METHOD FOR THEIR PRODUCTION | |
| JP4542696B2 (en) | Rotating anode X-ray tube target and method for manufacturing the same | |
| JP3320650B2 (en) | Tungsten or molybdenum metal material, method for manufacturing secondary product material using the metal material, and heat treatment apparatus for performing the method | |
| DE19527348A1 (en) | Electrode with heat sink |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
| AK | Designated contracting states |
Kind code of ref document: A2 Designated state(s): AT CH DE FR GB IT LI NL |
|
| PUAL | Search report despatched |
Free format text: ORIGINAL CODE: 0009013 |
|
| AK | Designated contracting states |
Kind code of ref document: A3 Designated state(s): AT CH DE FR GB IT LI NL |
|
| 17P | Request for examination filed |
Effective date: 19930204 |
|
| 17Q | First examination report despatched |
Effective date: 19930423 |
|
| GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
| AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AT CH DE FR GB IT LI NL |
|
| REF | Corresponds to: |
Ref document number: 108948 Country of ref document: AT Date of ref document: 19940815 Kind code of ref document: T |
|
| GBT | Gb: translation of ep patent filed (gb section 77(6)(a)/1977) |
Effective date: 19940725 |
|
| REF | Corresponds to: |
Ref document number: 59200292 Country of ref document: DE Date of ref document: 19940825 |
|
| ITF | It: translation for a ep patent filed |
Owner name: ING. ZINI MARANESI & C. S.R.L. |
|
| ET | Fr: translation filed | ||
| PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
| STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
| 26N | No opposition filed | ||
| REG | Reference to a national code |
Ref country code: GB Ref legal event code: IF02 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: CH Payment date: 20030422 Year of fee payment: 12 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: GB Payment date: 20030428 Year of fee payment: 12 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: NL Payment date: 20030506 Year of fee payment: 12 Ref country code: AT Payment date: 20030506 Year of fee payment: 12 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 20030512 Year of fee payment: 12 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 20030514 Year of fee payment: 12 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GB Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20040504 Ref country code: AT Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20040504 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: LI Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20040531 Ref country code: CH Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20040531 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NL Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20041201 Ref country code: DE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20041201 |
|
| GBPC | Gb: european patent ceased through non-payment of renewal fee |
Effective date: 20040504 |
|
| REG | Reference to a national code |
Ref country code: CH Ref legal event code: PL |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20050131 |
|
| NLV4 | Nl: lapsed or anulled due to non-payment of the annual fee |
Effective date: 20041201 |
|
| REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IT Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED. Effective date: 20050504 |