EP0488450B1 - X-Ray tube anode with oxide layer - Google Patents
X-Ray tube anode with oxide layer Download PDFInfo
- Publication number
- EP0488450B1 EP0488450B1 EP91203023A EP91203023A EP0488450B1 EP 0488450 B1 EP0488450 B1 EP 0488450B1 EP 91203023 A EP91203023 A EP 91203023A EP 91203023 A EP91203023 A EP 91203023A EP 0488450 B1 EP0488450 B1 EP 0488450B1
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- EP
- European Patent Office
- Prior art keywords
- layer
- anode
- ray
- intermediate layer
- oxidic
- 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.)
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- 239000010410 layer Substances 0.000 claims description 69
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 23
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 14
- 238000002844 melting Methods 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 10
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 9
- 229910052593 corundum Inorganic materials 0.000 claims description 9
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 8
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims description 6
- 239000011733 molybdenum Substances 0.000 claims description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 5
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 5
- 229910052721 tungsten Inorganic materials 0.000 claims description 5
- 239000010937 tungsten Substances 0.000 claims description 5
- 229910052681 coesite Inorganic materials 0.000 claims description 3
- 229910052906 cristobalite Inorganic materials 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- 239000000377 silicon dioxide Substances 0.000 claims description 3
- 235000012239 silicon dioxide Nutrition 0.000 claims description 3
- 230000000087 stabilizing effect Effects 0.000 claims description 3
- 229910052682 stishovite Inorganic materials 0.000 claims description 3
- 229910052905 tridymite Inorganic materials 0.000 claims description 3
- 229910045601 alloy Inorganic materials 0.000 claims description 2
- 239000000956 alloy Substances 0.000 claims description 2
- 239000002344 surface layer Substances 0.000 claims 4
- 230000032683 aging Effects 0.000 description 11
- 238000000576 coating method Methods 0.000 description 8
- 230000008018 melting Effects 0.000 description 8
- 238000000137 annealing Methods 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 229910001182 Mo alloy Inorganic materials 0.000 description 4
- 238000007750 plasma spraying Methods 0.000 description 4
- 238000003878 thermal aging Methods 0.000 description 3
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- 238000005137 deposition process Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 230000002028 premature Effects 0.000 description 2
- 229910004140 HfO Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 1
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum oxide Inorganic materials [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- KTUFCUMIWABKDW-UHFFFAOYSA-N oxo(oxolanthaniooxy)lanthanum Chemical compound O=[La]O[La]=O KTUFCUMIWABKDW-UHFFFAOYSA-N 0.000 description 1
- 238000005240 physical vapour deposition Methods 0.000 description 1
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000005488 sandblasting Methods 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- IATRAKWUXMZMIY-UHFFFAOYSA-N strontium oxide Inorganic materials [O-2].[Sr+2] IATRAKWUXMZMIY-UHFFFAOYSA-N 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 238000007669 thermal treatment Methods 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Images
Classifications
-
- 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
- H01J35/105—Cooling of rotating anodes, e.g. heat emitting layers or structures
Definitions
- the invention relates to an X-ray anode, in particular a rotating anode, with high heat emissivity, with a carbon-containing base body made of a high-melting material and a focal spot or focal path region made of a high-melting metal or its alloys, which has an oxidic covering layer with a coating on at least parts of the surface outside the focal path homogeneous melted phase.
- EP-A-0 172 491 describes an X-ray anode made of a molybdenum alloy, such as TZM, with an oxide coating from a mixture of 40-70% titanium oxide, the rest being stabilized oxides from the group ZrO2, HfO, MgO, CeO2, La2O3 and SrO.
- TZM molybdenum alloy
- HfO, MgO, CeO2, La2O3 and SrO oxide coating from the group ZrO2, HfO, MgO, CeO2, La2O3 and SrO.
- melting the oxide coating improves the thermal emission coefficient and improves the adhesion of the oxide layer to the base body.
- the disadvantage of such an X-ray anode is that the carbon contained in the base body of the rotating anode causes the oxidic cover layer to age rapidly, which leads to a premature deterioration in the thermal heat emission coefficient.
- AT-A-376 064 describes an X-ray tube rotating anode with a base body made of a carbon-containing molybdenum alloy, e.g. B. TZM, which is provided outside the focal path with a coating of one or more oxides or a mixture of one or more metals with one or more oxides to improve the heat emissivity.
- a 10 - 200 »m thick intermediate layer made of molybdenum and / or tungsten between the base body and the oxidic coating in order to prevent the rapid aging of the rotating anode and thus the premature reduction of the thermal emission coefficient.
- a disadvantage of such a rotating anode is that melted oxide cover layers are practically impossible to produce. It has been found that, depending on the type of application of the molybdenum and / or tungsten intermediate layer, the oxidic top layer cannot be melted at all or runs off from the surface to be coated during melting.
- the object of the present invention is therefore to provide an X-ray tube anode consisting of a carbon-containing base body and a melted oxide cover layer to increase the to create thermal emission coefficients which have a noticeably improved aging resistance with respect to the thermal emission coefficient compared to the prior art and in which the melting of the oxide cover layer into a homogeneous phase is possible without problems.
- a two-layer intermediate layer is arranged with a layer of molybdenum and / or tungsten and a layer of Al2O3 with 1 - 30 wt.
- the X-ray anodes according to the invention have an oxidic cover layer that adheres well to the base body and has good melting properties.
- the thermal emission coefficient is over 80% for suitable oxidic cover layers and deteriorates only insignificantly in the long-term operation of the X-ray anode.
- oxide cover layers can now be melted without problems and do not run off the surface during melting, cannot be explained ad hoc from the theoretical background .
- thermal coating processes such as. B. plasma spraying, for use.
- PVD and CVD processes in particular plasma CVD processes and sputtering processes, have also proven themselves.
- the oxide layer of the intermediate layer consists of Al2O3 with 5-20% by weight of TiO2 and the total layer thickness of the intermediate layer is between 10 and 100 »m.
- the molybdenum alloy TZM with typical 0.5% Ti, 0.7% Zr and 0 - 0.05% C has proven itself as the material for the base body.
- An X-ray rotating anode consisting of the molybdenum alloy TZM, has an approx. 2 mm thick W-Re layer in the focal path area.
- the anode surface is first provided with an intermediate layer according to the invention and then with an oxidic cover layer.
- a completely sintered and mechanically shaped X-ray anode on the back of the anode to be coated is cleaned and roughened by means of sandblasting and, if possible, immediately provided with a 20 »m thick molybdenum layer using plasma spraying under the usual process conditions.
- annealing takes place under a hydrogen atmosphere at about 1350 ° C. for about 2 hours.
- the oxide powder has the following composition: 68% by weight of ZrO2, 7.5% by weight of CaO, 19% by weight of TiO2 and 5.5% by weight of SiO2
- the rotating anode coated in this way must be subjected to an annealing treatment in order to make it useful for use in X-ray tubes.
- the rotating anode both the base material and the layer material, is largely freed of gas inclusions and of contaminants which are volatile at higher temperatures, in order to prevent electrical flashovers as a result of the release of gas inclusions when the rotating anode is later used in the high-vacuum X-ray tube.
- the degassing annealing takes place within a narrow temperature and time range, matched to the anode base material, in order to avoid undesired structural changes in the base material.
- the applied layer must also be treated within a very specific temperature and time range in order to achieve melting in the desired homogeneous phase and with a slightly nubbed surface structure (orange peel layer).
- the annealing is carried out at 1620 ° C. for 65 minutes.
- the melted layer has the desired degree of blackening and the desired surface structure (orange peel).
- There is no uncontrolled flow of the melting oxide layer especially not in the transition area between coated and uncoated parts of the rotating anode surface.
- gaseous oxides evaporate from the layer surface during the annealing process, these are struck not as a disruptive layer in the originally uncoated focal path area of the rotating anode.
- the rotating anode was then tested in an X-ray tube arrangement under practical conditions. It ran there for several days without any problems within the required limit load.
- An X-ray rotating anode consisting of a TZM base body and a 2 mm thick W-Re layer in the focal path area is produced like the rotating anode according to Example 1, with the exception that the oxidic cover layer has the following changed composition: 68% by weight ZrO2, 7.5% by weight CaO, 19% by weight TiO2 and 5.5% by weight Al2O3
- rotating anodes according to Examples 1 and 2 with rotating anodes which have the same oxidic cover layer but no intermediate layer according to the invention, are used with regard to their thermal emission factor as a function of temperature and time compared with each other.
- curve 1 shows the course of the thermal emission factor ⁇ of a rotating anode produced according to Example 1 as a function of the temperature.
- Curve 2 shows the corresponding course of a rotary anode produced in accordance with Example 1, but without an intermediate layer according to the invention. It can be seen that the course of these two curves is approximately the same.
- Curve 3 shows the course of the thermal emission factor ⁇ of a rotating anode produced according to Example 1 after thermal aging of the rotating anode. The aging takes place by annealing the rotating anode for ten hours at a temperature which is higher than the maximum temperature that later occurs during operation.
- Curve 4 shows the corresponding course of a thermally aged rotating anode produced in accordance with Example 1, but without an intermediate layer according to the invention. It can be clearly seen that the thermal emission coefficient shows only a slight deterioration even under long-term exposure due to the intermediate layer according to the invention, while the thermal emission coefficient of the rotating anode without the intermediate layer according to the invention drops significantly.
- FIG. 2 shows, analogously to FIG. 1, the corresponding curves of a rotating anode produced according to Example 2 with and without an intermediate layer before and after ten hours of aging, curve 1 of the rotating anode with an intermediate layer before aging, curve 2 of the rotating anode without Intermediate layer before aging, curve 3 of the rotating anode with intermediate layer after aging and curve 4 of the rotating anode without intermediate layer after aging. It can also be seen here that the intermediate layer according to the invention achieves a significantly improved aging resistance of the thermal emission factor.
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- Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
- Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
- Coating By Spraying Or Casting (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
Description
Die Erfindung betrifft eine Röntgenanode, insbesondere Drehanode, hoher Wärmeemissivität, mit einem Kohlenstoff enthaltenden Grundkörper aus einem hochschmelzenden Material sowie einem Brennfleck- bzw. Brennbahnbereich aus einem hochschmelzenden Metall oder dessen Legierungen, die zumindest auf Teilen der Oberfläche außerhalb der Brennbahn eine oxidische Deckschicht mit einer homogenen aufgeschmolzenen Phase aufweist.The invention relates to an X-ray anode, in particular a rotating anode, with high heat emissivity, with a carbon-containing base body made of a high-melting material and a focal spot or focal path region made of a high-melting metal or its alloys, which has an oxidic covering layer with a coating on at least parts of the surface outside the focal path homogeneous melted phase.
Bei Röntgenröhrenanoden wird die zugeführte elektrische Energie nur zu einem Bruchteil in Röntgenstrahlungs-Energie umgesetzt. Der Großteil der Energie wird in unerwünschte Wärme umgesetzt, was zu einer starken Temperatur-Belastung der Anoden führt. Es hat daher in der Vergangenheit nicht an Versuchen gefehlt, die in Röntgenanoden erzeugte Wärmeenergie so rasch wie möglich, vorwiegend durch Vergrößerung der oberflächlichen Wärmeemissivität, abzuführen. Eine bekannte Maßnahme, die Wärmeemissivität der Röntgenanoden zu vergrößern, ist die Aufbringung oxidischer überzüge, die einen bestimmten Anteil an Titandioxid erhalten, wodurch sich ein Schwärzungseffekt ergibt. Diese oxidischen Deckschichten werden nach dem Schichtauftrag vielfach noch durch eine thermische Behandlung aufgeschmolzen, wodurch der Wärmeemissionsfaktor noch weiter verbessert wird und eine verbesserte Haftung der überzugsschicht am Substratmaterial erreicht wird.With X-ray tube anodes, only a fraction of the electrical energy supplied is converted into X-ray energy. Most of the energy is converted into unwanted heat, which leads to a high temperature load on the anodes. There has been no lack of attempts in the past to dissipate the thermal energy generated in X-ray anodes as quickly as possible, predominantly by increasing the superficial heat emissivity. A known measure to increase the heat emissivity of the X-ray anodes is the application of oxidic coatings which receive a certain proportion of titanium dioxide, which results in a blackening effect. After the layer application, these oxide cover layers are often melted by a thermal treatment, whereby the heat emission factor is further improved and improved adhesion of the coating layer to the substrate material is achieved.
Die EP-A-0 172 491 beschreibt eine Röntgenanode aus einer Molybdänlegierung, wie TZM, mit einem Oxidüberzug aus einer Mischung von 40 - 70 % Titanoxid, der Rest stabilisierte Oxide aus der Gruppe ZrO₂, HfO, MgO, CeO₂, La₂O₃ und SrO. In dieser Vorveröffentlichung wird beschrieben, daß durch eine Aufschmelzung des oxidischen Überzuges eine Verbesserung des thermischen Emissionskoeffizienten und eine verbesserte Haftung der Oxidschicht am Grundkörper erreicht wird. Der Nachteil einer derartigen Röntgenanode besteht darin, daß der im Grundkörper der Drehanode enthaltene Kohlenstoff eine starke Alterung der oxidischen Deckschicht bewirkt, was zu einer vorzeitigen Verschlechterung des thermischen Wärmeemissions-Koeffizienten führt.EP-A-0 172 491 describes an X-ray anode made of a molybdenum alloy, such as TZM, with an oxide coating from a mixture of 40-70% titanium oxide, the rest being stabilized oxides from the group ZrO₂, HfO, MgO, CeO₂, La₂O₃ and SrO. In this prior publication, it is described that melting the oxide coating improves the thermal emission coefficient and improves the adhesion of the oxide layer to the base body. The disadvantage of such an X-ray anode is that the carbon contained in the base body of the rotating anode causes the oxidic cover layer to age rapidly, which leads to a premature deterioration in the thermal heat emission coefficient.
Die AT-A-376 064 beschreibt eine Röntgenröhren-Drehanode mit einem Grundkörper, aus einer Kohlenstoff enthaltenden Molybdänlegierung, z. B. TZM, die außerhalb der Brennbahn mit einem Überzug aus einem oder mehreren Oxiden oder aus einem Gemisch aus einem oder mehreren Metallen mit einem oder mehreren Oxiden zur Verbesserung der Wärmeemissivität versehen ist. Entsprechend dieser Vorveröffentlichung wird vorgeschlagen, zwischen Grundkörper und oxidischen Überzug eine 10 - 200 »m dicke Zwischenschicht aus Molybdän und/oder Wolfram anzuordnen, um auf diese Art und Weise die rasche Alterung der Drehanode und damit die vorzeitige Verminderung des thermischen Emissionskoeffizienten zu verhindern. Nachteilig bei einer derartigen Drehanode ist, daß aufgeschmolzene oxidische Deckschichten praktisch nicht herstellbar sind. Es ist festgestellt worden, daß je nach Art der Aufbringung der Molybdän- und/oder Wolfram-Zwischenschicht die oxidische Deckschicht überhaupt nicht zum Aufschmelzen gebracht werden kann oder beim Aufschmelzen von der zu beschichtenden Oberfläche abläuft.AT-A-376 064 describes an X-ray tube rotating anode with a base body made of a carbon-containing molybdenum alloy, e.g. B. TZM, which is provided outside the focal path with a coating of one or more oxides or a mixture of one or more metals with one or more oxides to improve the heat emissivity. According to this prior publication, it is proposed to arrange a 10 - 200 »m thick intermediate layer made of molybdenum and / or tungsten between the base body and the oxidic coating in order to prevent the rapid aging of the rotating anode and thus the premature reduction of the thermal emission coefficient. A disadvantage of such a rotating anode is that melted oxide cover layers are practically impossible to produce. It has been found that, depending on the type of application of the molybdenum and / or tungsten intermediate layer, the oxidic top layer cannot be melted at all or runs off from the surface to be coated during melting.
Die Aufgabe der vorliegenden Erfindung ist es daher, eine Röntgenröhrenanode, bestehend aus einem kohlenstoffhältigen Grundkörper sowie einer aufgeschmolzenen oxidischen Deckschicht zur Erhöhung des thermischen Emissionskoeffizienten zu schaffen, die gegenüber dem Stand der Technik eine merklich verbesserte Alterungsbeständigkeit im Hinblick auf den thermischen Emissionskoeffizienten aufweist und bei der die Aufschmelzung der oxidischen Deckschicht zu einer homogenen Phase ohne Probleme möglich ist.The object of the present invention is therefore to provide an X-ray tube anode consisting of a carbon-containing base body and a melted oxide cover layer to increase the to create thermal emission coefficients which have a noticeably improved aging resistance with respect to the thermal emission coefficient compared to the prior art and in which the melting of the oxide cover layer into a homogeneous phase is possible without problems.
Erfindungsgemäß wird dies dadurch erreicht, daß zwischen Grundkörper und oxidischer Deckschicht eine zweilagige Zwischenschicht mit ausgehend vom Grundkörper einer Lage Molybdän und/oder Wolfram und einer Lage Al₂O₃ mit 1 - 30 Gew.%-Anteilen TiO₂ angeordnet ist.According to the invention this is achieved in that a two-layer intermediate layer is arranged with a layer of molybdenum and / or tungsten and a layer of Al₂O₃ with 1 - 30 wt.
Die erfindungsgemäßen Röntgenanoden weisen durch die spezielle Zwischenschicht eine ausgezeichnet auf dem Grundkörper haftende, gute aufschmelzbare oxidische Deckschicht auf. Der thermische Emissionskoeffizient liegt für geeignete oxidische Deckschichten über 80 % und verschlechtert sich im Langzeitbetrieb der Röntgenanode nur unwesentlich.Due to the special intermediate layer, the X-ray anodes according to the invention have an oxidic cover layer that adheres well to the base body and has good melting properties. The thermal emission coefficient is over 80% for suitable oxidic cover layers and deteriorates only insignificantly in the long-term operation of the X-ray anode.
Der Effekt, daß sich durch Ergänzen der bekannten Zwischenschicht aus Molybdän und/oder Wolfram durch eine weitere oxidische Lage ganz spezieller Zusammensetzung oxidische Deckschichten nunmehr problemlos aufschmelzen lassen und bei der Aufschmelzung nicht von der Oberfläche ablaufen, ist von den theoretischen Hintergründen her nicht ad hoc erklärbar.The effect that by supplementing the known intermediate layer made of molybdenum and / or tungsten with a further oxidic layer of a very special composition, oxide cover layers can now be melted without problems and do not run off the surface during melting, cannot be explained ad hoc from the theoretical background .
Als Abscheideverfahren für die Zwischenschicht und die oxidische Deckschicht kommen vorzugsweise thermische Beschichtungsverfahren, wie z. B. Plasmaspritzen, zur Anwendung. Andere Abscheideverfahren, wie PVD- und CVD-Verfahren, insbesondere Plasma-CVD-Verfahren und Sputterverfahren, haben sich jedoch ebenso bewährt.As a deposition process for the intermediate layer and the oxidic top layer preferably thermal coating processes such as. B. plasma spraying, for use. However, other deposition processes, such as PVD and CVD processes, in particular plasma CVD processes and sputtering processes, have also proven themselves.
Die besten Ergebnisse hinsichtlich Aufschmelzeigenschaften und Alterungsbeständigkeit werden erzielt, wenn die oxidsche Lage der Zwischenschicht aus Al₂O₃ mit 5 - 20 Gew.%-Anteilen TiO₂ besteht und die Gesamtschichtstarke der Zwischenschicht zwischen 10 und 100 »m beträgt.The best results with regard to melting properties and aging resistance are achieved if the oxide layer of the intermediate layer consists of Al₂O₃ with 5-20% by weight of TiO₂ and the total layer thickness of the intermediate layer is between 10 and 100 »m.
Als aufgeschmolzene oxidische Deckschichten haben sich insbesondere Mischungen aus ZrO₂, TiO₂ und Al₂O₃ sowie Mischungen aus TiO₂, ZrO₂, Al₂O₃ und/oder SiO₂ jeweils mit oder ohne stabilisierende Oxide wie CaO und/oder Y₂O₃ bewährt.Mixtures of ZrO₂, TiO₂ and Al₂O₃ and mixtures of TiO₂, ZrO₂, Al₂O₃ and / or SiO₂, each with or without stabilizing oxides such as CaO and / or Y₂O₃, have proven particularly useful as melted oxide cover layers.
Als Material für den Grundkörper hat sich insbesondere die Molybdänlegierung TZM mit typisch 0,5 % Ti, 0,7 % Zr und 0 - 0,05 % C bewährt.In particular, the molybdenum alloy TZM with typical 0.5% Ti, 0.7% Zr and 0 - 0.05% C has proven itself as the material for the base body.
Im folgenden wird die Erfindung anhand von Beispielen näher erläutert.The invention is explained in more detail below with the aid of examples.
Eine Röntgendrehanode, bestehend aus der Molybdänlegierung TZM, weist im Brennbahnbereich eine ca. 2 mm dicke W-Re-Schicht auf. Zur Erhöhung der Wärmeabstrahlfähigkeit wird die Anodenoberfläche zuerst mit einer erfindungsgemäßen Zwischenschicht und dann mit einer oxidischen Deckschicht versehen. Dazu wird eine fertig gesinterte und mechanisch umgeformte Röntgenanode auf der zu beschichtenden Anoden-Rückseite mittels Sandstrahlen gereinigt und aufgerauht und möglichst gleich anschließend unter den üblichen Verfahrensbedingungen mittels Plasmaspritzens mit einer 20 »m starken Molybdänschicht versehen. Nach dieser Beschichtung erfolgt eine Glühung unter Wasserstoffatmosphäre bei ca. 1350°C während etwa 2 Stunden. Dann erfolgt abermals durch Plasmaspritzen die Aufbringung einer oxidischen Schicht mit 13 Gew.% TiO₂, Rest Al₂O₃ in einer Schichtstärke von 20 »m.
Unmittelbar darauf erfolgt die Aufbringung der oxidischen Deckschicht in einer Schichtstärke von 20 »m ebenfalls durch Plasmaspritzen unter den üblichen Verfahrensbedingungen.
Das Oxidpulver weist folgende Zusammensetzung auf:
68 Gew.% ZrO₂, 7,5 Gew.% CaO, 19 Gew.% TiO₂ sowie 5,5 Gew.% SiO₂ Die so beschichtete Drehanode muß einer Glühbehandlung unterworfen werden, um sie für den Einsatz in Röntgenröhren brauchbar zu machen. Durch die Glühung wird die Drehanode, und zwar sowohl das Grundmaterial als auch das Schichtmaterial von Gaseinschlüssen sowie von bei höheren Temperaturen flüchtigen Verunreinigungen weitgehend befreit, um beim späteren Einsatz der Drehanode in der Hochvakuum-Röntgenröhre elektrische Überschläge als Folge der Freisetzung von Gaseinschlüssen auszuschalten. Die Entgasungsglühung erfolgt, abgestimmt auf das Anoden-Grundmaterial, innerhalb eines engen Temperatur- und Zeitbereiches, um unerwünschte Strukturänderungen des Grundmaterials zu vermeiden. Andererseits muß die aufgetragene Schicht in Abhängigkeit von deren Zusammensetzung ebenfalls innerhalb eines sehr spezifischen Temperatur- und Zeitbereiches behandelt werden, um ein Aufschmelzen in der gewünschten homogenen Phase und mit einer leicht genoppten Oberflächenstruktur (Orangenhautschicht) zu erzielen.
Die Glühung erfolgt im vorliegenden Fall bei 1620°C während 65 Minuten. Die aufgeschmolzene Schicht weist den gewünschten Schwärzungsgrad sowie die angestrebte Oberflächenstruktur (Orangenhaut) auf. Es kommt zu keinem unkontrollierten Fließen der aufschmelzenden Oxidschicht, insbesondere nicht im Übergangsbereich zwischen beschichteten und unbeschichteten Teilen der Drehanodenoberfläche. Soweit während des Glühvorganges gasförmige Oxide von der Schichtoberflache abdampfen, schlagen sich diese nicht als störender Schichtbelag im ursprünglich nicht beschichteten Brennbahnbereich der Drehanode nieder.
Die Drehanode wurde anschließend in einer Röntgenröhren-Versuchsanordnung unter praxisnahen Bedingungen erprobt. Sie lief dort über mehrere Tage störungsfrei innerhalb der geforderten Grenzbelastung.An X-ray rotating anode, consisting of the molybdenum alloy TZM, has an approx. 2 mm thick W-Re layer in the focal path area. To increase the heat radiation capability, the anode surface is first provided with an intermediate layer according to the invention and then with an oxidic cover layer. For this purpose, a completely sintered and mechanically shaped X-ray anode on the back of the anode to be coated is cleaned and roughened by means of sandblasting and, if possible, immediately provided with a 20 »m thick molybdenum layer using plasma spraying under the usual process conditions. After this coating, annealing takes place under a hydrogen atmosphere at about 1350 ° C. for about 2 hours. Then done again Plasma spraying the application of an oxide layer with 13 wt.% TiO₂, the rest Al₂O₃ in a layer thickness of 20 »m.
Immediately afterwards, the oxide cover layer is applied in a layer thickness of 20 »m, likewise by plasma spraying under the usual process conditions.
The oxide powder has the following composition:
68% by weight of ZrO₂, 7.5% by weight of CaO, 19% by weight of TiO₂ and 5.5% by weight of SiO₂ The rotating anode coated in this way must be subjected to an annealing treatment in order to make it useful for use in X-ray tubes. As a result of the annealing, the rotating anode, both the base material and the layer material, is largely freed of gas inclusions and of contaminants which are volatile at higher temperatures, in order to prevent electrical flashovers as a result of the release of gas inclusions when the rotating anode is later used in the high-vacuum X-ray tube. The degassing annealing takes place within a narrow temperature and time range, matched to the anode base material, in order to avoid undesired structural changes in the base material. On the other hand, depending on its composition, the applied layer must also be treated within a very specific temperature and time range in order to achieve melting in the desired homogeneous phase and with a slightly nubbed surface structure (orange peel layer).
In the present case, the annealing is carried out at 1620 ° C. for 65 minutes. The melted layer has the desired degree of blackening and the desired surface structure (orange peel). There is no uncontrolled flow of the melting oxide layer, especially not in the transition area between coated and uncoated parts of the rotating anode surface. Insofar as gaseous oxides evaporate from the layer surface during the annealing process, these are struck not as a disruptive layer in the originally uncoated focal path area of the rotating anode.
The rotating anode was then tested in an X-ray tube arrangement under practical conditions. It ran there for several days without any problems within the required limit load.
Eine Röntgendrehanode aus einem TZM-Grundkörper und einer 2 mm dicken W-Re-Schicht im Brennbahnbereich wird wie die Drehanode entsprechend Beispiel 1 hergestellt, mit der Ausnahme, daß die oxidische Deckschicht folgende geänderte Zusammensetzung aufweist:
68 Gew.% ZrO₂, 7,5 Gew.% CaO, 19 Gew.% TiO₂ sowie 5,5 Gew.% Al₂O₃An X-ray rotating anode consisting of a TZM base body and a 2 mm thick W-Re layer in the focal path area is produced like the rotating anode according to Example 1, with the exception that the oxidic cover layer has the following changed composition:
68% by weight ZrO₂, 7.5% by weight CaO, 19% by weight TiO₂ and 5.5% by weight Al₂O₃
Zum Nachweis, daß die erfindungsgemäße Zwischenschicht die Alterungsbeständigkeit des thermischen Emissionskoeffizienten gegenüber Drehanoden ohne Zwischenschicht deutlich verbessert, werden Drehanoden entsprechend den Beispielen 1 und 2 mit Drehanoden, die dieselbe oxidische Deckschicht jedoch keine erfindungsgemäße Zwischenschicht aufweisen, hinsichtlich ihres thermischen Emissionsfaktors in Abhängigkeit von Temperaturen und Zeit miteinander verglichen.To prove that the intermediate layer according to the invention significantly improves the aging resistance of the thermal emission coefficient compared to rotating anodes without an intermediate layer, rotating anodes according to Examples 1 and 2 with rotating anodes, which have the same oxidic cover layer but no intermediate layer according to the invention, are used with regard to their thermal emission factor as a function of temperature and time compared with each other.
Die Erfindung wird dabei anhand von Figuren näher erläutert.The invention is explained in more detail with reference to figures.
Es zeigen
Figur 1- ein Diagramm, das die Temperaturabhängigkeit des thermischen Emissionsfaktors ε der nach
Beispiel 1 hergestellten Drehanode sowie einer entsprechenden Drehanode ohne Zwischenschicht jeweils mit und ohne thermischer Alterung wiedergibt Figur 2- ein Diagramm, das die Temperaturabhängigkeit des thermischen Emissionsfaktors ε der nach
Beispiel 2 hergestellten Drehanode sowie einer entsprechenden Drehanode ohne Zwischenschicht jeweils mit und ohne thermischer Alterung wiedergibt.
- Figure 1
- a diagram that shows the temperature dependence of the thermal emission factor ε of the rotating anode produced according to Example 1 and a corresponding rotating anode without an intermediate layer in each case with and without thermal aging
- Figure 2
- a diagram that shows the temperature dependence of the thermal emission factor ε of the rotating anode produced according to Example 2 and a corresponding rotating anode without an intermediate layer in each case with and without thermal aging.
In Figur 1 zeigt die Kurve 1 den Verlauf des thermischen Emissionsfaktors ε einer nach Beispiel 1 hergestellten Drehanode in Abhängigkeit von der Temperatur.
Kurve 2 zeigt den entsprechenden Verlauf einer entsprechend Beispiel 1, jedoch ohne erfindungsgemäße Zwischenschicht, hergestellten Drehanode. Es ist zu sehen, daß der Verlauf dieser beiden Kurven etwa gleich ist. Kurve 3 zeigt den Verlauf des thermischen Emissionsfaktors ε einer nach Beispiel 1 hergestellten Drehanode nach einer thermischen Alterung der Drehanode. Die Alterung erfolgt durch eine zehnstündige Glühung der Drehanode bei einer Temperatur, die über der späteren im Betrieb auftretenden maximalen Temperatur liegt.
Kurve 4 zeigt den entsprechenden Verlauf einer entsprechend Beispiel 1, jedoch ohne erfindungsgemäße Zwischenschicht, hergestellten, thermisch gealterten Drehanode.
Es ist klar zu sehen, daß durch die erfindungsgemäße Zwischenschicht der thermische Emissionskoeffizient auch bei Langzeitbelastung eine nur geringfügige Verschlechterung zeigt, während der thermische Emissionskoeffizient der Drehanode ohne erfindungsgemäße Zwischenschicht signifikant absinkt.In FIG. 1,
It can be clearly seen that the thermal emission coefficient shows only a slight deterioration even under long-term exposure due to the intermediate layer according to the invention, while the thermal emission coefficient of the rotating anode without the intermediate layer according to the invention drops significantly.
Figur 2 Zeigt analog wie Figur 1 die entsprechenden Kurven einer nach Beispiel 2 hergestellten Drehanode mit und ohne Zwischenschicht vor und nach zehnstündiger Alterung, wobei Kurve 1 der Drehanode mit Zwischenschicht vor der Alterung, Kurve 2 der Drehanode ohne Zwischenschicht vor der Alterung, Kurve 3 der Drehanode mit Zwischenschicht nach der Alterung und Kurve 4 der Drehanode ohne Zwischenschicht nach der Alterung entsprechen. Auch hier ist zu sehen, daß durch die erfindungsgemäße Zwischenschicht eine wesentlich verbesserte Alterungsbeständigkeit des thermischen Emissionsfaktors erreicht wird.FIG. 2 shows, analogously to FIG. 1, the corresponding curves of a rotating anode produced according to Example 2 with and without an intermediate layer before and after ten hours of aging, curve 1 of the rotating anode with an intermediate layer before aging,
Claims (6)
- X-ray anode in particular a rotary anode of high heat emissivity having a carbon-containing base member made of a high-melting material and a focal spot or focal path region made of a high-melting metal or its alloys, which anode comprises at least on parts of the surface externally of the focal path an oxidic surface layer with a homogeneously melted-on phase, characterized in that a two-layer intermediate layer with, starting from the base member, a layer of molybdenum and/or tungsten and a layer of Al₂O₃ with 1 - 30 weight% portions of TiO₂ is disposed between the base member and the oxidic surface layer.
- X-ray anode in particular a rotary anode according to Claim 1, characterized in that the oxidic layer of the intermediate layer consists of Al₂O₃ with 5 - 20 weight % portions of TiO₂.
- X-ray anode in particular a rotary anode according to Claim 1 or 2, characterized in that the total layer thickness of the intermediate layer is between 10 and 100 »m.
- X-ray anode in particular a rotary anode according to any one of Claims 1 to 3, characterized in that the oxidic surface layer consists of a mixture of ZrO₂, TiO₂ and Al₂O₃ if necessary with stabilizing oxides such as CaO and/or Y₂O₃.
- X-ray anode in particular a rotary anode according to any one of Claims 1 to 3, characterized in that the oxidic surface layer consists of a mixture of TiO₂, ZrO₂ and SiO₂ if necessary with stabilizing oxides such as CaO and/or Y₂O₃.
- X-ray anode in particular a rotary anode according to any one of Claims 1 to 5, characterized in that the base member consists of TZM.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT2421/90 | 1990-11-30 | ||
| AT0242190A AT394642B (en) | 1990-11-30 | 1990-11-30 | X-RAY TUBE ANODE WITH OXIDE COATING |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0488450A1 EP0488450A1 (en) | 1992-06-03 |
| EP0488450B1 true EP0488450B1 (en) | 1995-03-08 |
Family
ID=3534049
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP91203023A Expired - Lifetime EP0488450B1 (en) | 1990-11-30 | 1991-11-20 | X-Ray tube anode with oxide layer |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5157706A (en) |
| EP (1) | EP0488450B1 (en) |
| JP (1) | JPH04269436A (en) |
| AT (1) | AT394642B (en) |
| DE (1) | DE59104875D1 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5264801A (en) * | 1992-05-05 | 1993-11-23 | Picker International, Inc. | Active carbon barrier for x-ray tube targets |
| US20040194146A1 (en) * | 2000-02-15 | 2004-09-30 | Bates Cary Lee | Set top box and methods for using the same |
| US6693990B1 (en) | 2001-05-14 | 2004-02-17 | Varian Medical Systems Technologies, Inc. | Low thermal resistance bearing assembly for x-ray device |
| US7004635B1 (en) | 2002-05-17 | 2006-02-28 | Varian Medical Systems, Inc. | Lubricated ball bearings |
| US6751292B2 (en) * | 2002-08-19 | 2004-06-15 | Varian Medical Systems, Inc. | X-ray tube rotor assembly having augmented heat transfer capability |
| DE102005039188B4 (en) * | 2005-08-18 | 2007-06-21 | Siemens Ag | X-ray tube |
| DE102005039187B4 (en) * | 2005-08-18 | 2012-06-21 | Siemens Ag | X-ray tube |
| US20080081122A1 (en) * | 2006-10-03 | 2008-04-03 | H.C. Starck Inc. | Process for producing a rotary anode and the anode produced by such process |
| CN111415852B (en) * | 2020-05-06 | 2024-02-09 | 上海联影医疗科技股份有限公司 | Anode assembly of X-ray tube, X-ray tube and medical imaging equipment |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL7312945A (en) * | 1973-09-20 | 1975-03-24 | Philips Nv | TURNTABLE FOR A ROSE TUBE AND METHOD FOR MANUFACTURE OF SUCH ANODE. |
| AT336143B (en) * | 1975-03-19 | 1977-04-25 | Plansee Metallwerk | X-ray anode |
| AT337314B (en) * | 1975-06-23 | 1977-06-27 | Plansee Metallwerk | X-ray anode |
| AT376064B (en) * | 1982-02-18 | 1984-10-10 | Plansee Metallwerk | X-RAY TUBE ROTATING ANODE |
| DE3226858A1 (en) * | 1982-07-17 | 1984-01-19 | Philips Patentverwaltung Gmbh, 2000 Hamburg | TURNING ANODE TUBE TUBES |
| US4600659A (en) * | 1984-08-24 | 1986-07-15 | General Electric Company | Emissive coating on alloy x-ray tube target |
| US4840850A (en) * | 1986-05-09 | 1989-06-20 | General Electric Company | Emissive coating for X-ray target |
| US4870672A (en) * | 1987-08-26 | 1989-09-26 | General Electric Company | Thermal emittance coating for x-ray tube target |
| US4953190A (en) * | 1989-06-29 | 1990-08-28 | General Electric Company | Thermal emissive coating for x-ray targets |
-
1990
- 1990-11-30 AT AT0242190A patent/AT394642B/en not_active IP Right Cessation
-
1991
- 1991-11-15 JP JP3326633A patent/JPH04269436A/en not_active Withdrawn
- 1991-11-20 DE DE59104875T patent/DE59104875D1/en not_active Expired - Fee Related
- 1991-11-20 EP EP91203023A patent/EP0488450B1/en not_active Expired - Lifetime
- 1991-11-21 US US07/795,790 patent/US5157706A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| AT394642B (en) | 1992-05-25 |
| ATA242190A (en) | 1991-10-15 |
| EP0488450A1 (en) | 1992-06-03 |
| JPH04269436A (en) | 1992-09-25 |
| US5157706A (en) | 1992-10-20 |
| DE59104875D1 (en) | 1995-04-13 |
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