EP0487144A1 - Anode pour tube à rayons X munie d'une couche d'oxyde - Google Patents

Anode pour tube à rayons X munie d'une couche d'oxyde Download PDF

Info

Publication number
EP0487144A1
EP0487144A1 EP91202965A EP91202965A EP0487144A1 EP 0487144 A1 EP0487144 A1 EP 0487144A1 EP 91202965 A EP91202965 A EP 91202965A EP 91202965 A EP91202965 A EP 91202965A EP 0487144 A1 EP0487144 A1 EP 0487144A1
Authority
EP
European Patent Office
Prior art keywords
oxide
weight
coating
layer
ray
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.)
Withdrawn
Application number
EP91202965A
Other languages
German (de)
English (en)
Inventor
Wolfgang Hohenauer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Plansee SE
Original Assignee
Plansee SE
Metallwerk Plansee GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Plansee SE, Metallwerk Plansee GmbH filed Critical Plansee SE
Publication of EP0487144A1 publication Critical patent/EP0487144A1/fr
Withdrawn legal-status Critical Current

Links

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 base body made of a high-melting metal or its alloys and a focal spot or focal path region made of a high-melting metal or its alloys, which directly or above at least on parts of the surface outside the focal path has an underlayer on the base body applied oxidic coating as a homogeneous, melted phase, which contains oxides of the metals Ti, Zr and Al and is optionally stabilized by another oxide.
  • X-ray tube anodes only emit a fraction of the radiated energy in the form of X-rays. The rest is transferred to heat and has to leave the anode in the form of heat radiation. It has therefore been known for many years to improve the heat emissivity of X-ray anodes from high-melting metals by means of an oxidic coating (AT-PS 337 314, DE-OS 22 01 979, DE-OS 24 43 354). These prior publications claim to increase the adhesion of the oxide layer on the surface of the base metal compared to the prior art and to increase the thermal emissivity of the anode surface by means of different oxide materials and production processes. It has been shown that the performance of layers produced in this way is limited in view of the continuously increasing requirements for X-ray anodes with regard to layer aging, heat radiation capability and the resistance to degassing (avoidance of electrical flashovers).
  • DE-OS 22 01 979 describes in particular an oxide layer which consists of the heating product of a mixture which contains titanium dioxide and additives of at least one other meltable oxide.
  • Aluminum oxide, calcium oxide, magnesium oxide and zirconium oxide are mentioned as other, equally suitable oxides. Particular advantages of a very special oxide combination are not mentioned.
  • As a preferred oxide mixture a mixture of approximately equal proportions of aluminum oxide and titanium dioxide can be found in the examples and the subclaims. Furthermore, it can be seen from the description that it is important that the titanium dioxide content does not drop below 20%.
  • the EU A2 0 172 491 describes in a further development an X-ray anode made of a molybdenum alloy with an oxide coating from a mixture of 40% - 70% titanium oxide, the rest of the stabilizing oxides from the group ZrO2, HfO, MgO, CeO2, La2O3 and SrO.
  • this prior publication has in particular the task of melting the oxides into smooth, shiny, shimmering layers by means of economical processes.
  • EU A2 0 244 776 relates essentially to the same subject of the invention.
  • the invention relates to the pretreatment of the oxidic material before application to the X-ray anode by means of conventional spraying techniques.
  • a mixture of 77% -85% titanium dioxide with 15-23% by weight calcium oxide is processed in a first process step into a powder with a homogeneous phase and then optionally mixed with other oxide powders by known spraying methods.
  • coating processes for the oxide coating on the X-ray anodes made of refractory metals are called plasma spraying, sputtering processes, chemical and physical deposition processes from the gas phase or the electron beam process.
  • An X-ray anode made of refractory metal is usually subjected to a degassing annealing at the end of the manufacturing process.
  • the degassing annealing of the anode serves to avoid gas leaks and consequently highly undesirable flashovers between the electrodes when they are used in an X-ray tube in a high vacuum.
  • the inventive teaching of this prior publication includes an advantageous coordination of the material composition of the oxide layer with regard to the annealing treatment after the coating of the X-ray anodes.
  • These degassing anneals simultaneously serve for the final formation and melting of the oxide phase, ie the conversion into a state which cannot be achieved by an oxide application process such as the plasma spraying process alone.
  • the layer composition according to the prior publication and the processes for its production do not adequately meet the requirements. Rather, when annealing the oxide layers according to this prior publication, there is the risk that at an annealing temperature at which the oxides melt into smooth, well-adhering layers, these are already so thin that the contour between coated and uncoated parts of the X-ray anode surface is undesirable, in Area of the focal path disappears to an intolerable extent. In addition, such oxide layers have an annoying gas phase formation at the required annealing temperatures.
  • the US-PS 4 870 672 describes an oxidic coating for X-ray anodes, consisting of a mixture of Al2O3, ZrO2 and TiO2.
  • the preferred composition of the coating consists of 40 - 70 wt.% TiO2, 20 - 40 wt.% ZrO2 and 10 - 20 wt.% Al2O3.
  • the Limit compositions of the coating are given with 10 - 80 wt.% TiO2, 10 - 60 wt.% ZrO2 and 5 - 30 wt.% Al2O3.
  • a disadvantage of this coating is that if the composition is chosen in an unfavorable manner, the coating evaporates and thus fogging and flashover may occur in the X-ray anode.
  • the object of the present invention is therefore to give the oxidic surface layer such a composition that, on its one hand, at least maintain the good adhesion properties between the oxide layer and the substrate and the good thermal emissivity properties of the layer which have been achievable so far when it is produced by customary application methods, including annealing treatment not be surpassed.
  • the structural structure and the composition of the oxide layer should allow easier technical handling in the production of the layer, in particular with regard to smooth melting without annoying evaporation and unwanted flow of the oxide during the annealing treatment of the X-ray anode.
  • the composition is also intended to prevent fogging or electrical flashovers in the X-ray tube.
  • the object is achieved in that the coating 1-20% by weight of aluminum oxide, less than 20% by weight of titanium dioxide and more than 60% by weight. Contains zirconium oxide.
  • the oxide layer according to the invention applied to an X-ray anode made of high-melting metals, has excellent adhesion, smooth surfaces and a high thermal heat coefficient ⁇ ⁇ 0.80.
  • the oxidic layer has the decisive advantage over the prior art that, under otherwise comparable conditions, during the required annealing treatment of the Anode is less liquid, ie the melt toughness is higher compared to previously known oxide layers when melting during the annealing treatment.
  • the contours between surface parts with and without oxide coating do not melt. There is only a comparatively small amount of evaporation and unwanted precipitation of oxide components on uncoated surface parts during the annealing process.
  • layers with a desired surface roughness R T of approx. 20 ⁇ m and the appearance of an orange peel can be achieved.
  • X-ray rotary anodes are currently usually made from the refractory metals tungsten, molybdenum or molybdenum alloys, in particular the carbon-containing alloy TZM.
  • the oxidic coating has the previously preferred oxide components zirconium oxide, calcium oxide and titanium dioxide, for example in a ratio of 75: 10: 15, it being essential that the titanium dioxide always contains less than 20% by weight and the zirconium oxide contains more than 60%. is present in the oxide mixture.
  • the calcium oxide can be partially or completely replaced by other stabilizing oxides known for such applications and can also be supplemented by small proportions of other, thermally stable compounds such as borides and / or nitrides.
  • the remaining part of the composition of the oxidic coating is, according to the invention, aluminum oxide with a weight fraction of 1-20%, preferably 4-7%.
  • the thickness of the oxide layer can vary between a few and a few thousand micrometers, depending on the deposition process.
  • the known PVD and CVD processes in particular plasma CVD processes and sputtering processes, as well as thermal coating processes such as e.g. B. plasma spraying.
  • the homogeneous phase in the oxidic coating is to be understood as a finely divided oxide mixture.
  • the desired oxide layer structure and surface roughness can be achieved with good adhesion between the layer and the base material by means of annealing at temperatures between 1550 o C and 1680 o C and a glow time between 30 minutes and 1.5 hours achieve advantageous.
  • the molybdenum alloy TZM with low carbon content tends to release carbon at higher temperatures.
  • the released carbon forms volatile CO or CO2 with the oxygen components of the oxide in the oxide layer and results in premature aging of the layer.
  • TZM as the base material in individual embodiments of the invention to arrange a diffusion barrier between the base material and the oxide layer with a layer thickness of a few micrometers up to the millimeter range in the form of a single-layer molybdenum layer or a two-layer Mo / oxide composite layer.
  • An X-ray rotary anode consisting of an alloy of molybdenum to which 5% by weight of tungsten has been added, has an approx. 2 mm in the focal path area thick W-Re layer.
  • this anode surface is provided with an oxide layer according to the invention.
  • a completely sintered and mechanically formed X-ray anode on the back of the anode to be coated is cleaned and roughened by means of sandblasting and, if possible, immediately afterwards coated with oxide powder under the usual process conditions by plasma spraying.
  • the oxide powder applied has the following composition: 89% by weight of an oxide mixture of 72% by weight of ZrO2, 8% by weight of CaO, 20% by weight of TiO2; further 11 wt.% Al2O3.
  • the rotating anode coated in this way must be subjected to an annealing treatment in order to make it usable 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 subsequently 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).
  • annealing takes place at 1620 o 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. So far during the annealing process vaporize gaseous oxides from the surface of the layer, these do not form 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 smoothly for several days within the required limit load.

Landscapes

  • Other Surface Treatments For Metallic Materials (AREA)
EP91202965A 1990-11-22 1991-11-14 Anode pour tube à rayons X munie d'une couche d'oxyde Withdrawn EP0487144A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT236790 1990-11-22
AT2367/90 1990-11-22

Publications (1)

Publication Number Publication Date
EP0487144A1 true EP0487144A1 (fr) 1992-05-27

Family

ID=3533054

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91202965A Withdrawn EP0487144A1 (fr) 1990-11-22 1991-11-14 Anode pour tube à rayons X munie d'une couche d'oxyde

Country Status (3)

Country Link
US (1) US5199059A (fr)
EP (1) EP0487144A1 (fr)
JP (1) JPH04267040A (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7180981B2 (en) * 2002-04-08 2007-02-20 Nanodynamics-88, Inc. High quantum energy efficiency X-ray tube and targets
DE102010040407A1 (de) 2010-09-08 2012-03-08 Siemens Aktiengesellschaft Röntgenröhre
CN102437000B (zh) * 2011-12-06 2014-12-31 肖李鹏 医用x射线管旋转阳极高热辐射陶瓷涂层及其制作方法
RU2653508C1 (ru) * 2017-05-30 2018-05-10 Федеральное государственное бюджетное образовательное учреждение высшего образования "Рязанский государственный радиотехнический университет" Микрофокусная рентгеновская трубка прострельного типа с высоким уровнем рассеиваемой на аноде мощности
CN116715438B (zh) * 2023-05-26 2025-10-31 上海大学 一种钼合金表面抗氧化涂层、其制备方法及其应用
WO2025070721A1 (fr) * 2023-09-29 2025-04-03 株式会社 東芝 Électrode positive rotative pour tube à rayons x, tube à rayons x, dispositif d'inspection par rayons x et procédé de fabrication d'électrode positive rotative pour tube à rayons x

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2381834A1 (fr) * 1977-02-16 1978-09-22 Gen Electric Anode perfectionnee pour tube a rayons x
US4870672A (en) * 1987-08-26 1989-09-26 General Electric Company Thermal emittance coating for x-ray tube target
EP0421521A2 (fr) * 1989-10-02 1991-04-10 Metallwerk Plansee Gesellschaft M.B.H. Anode pour tube à rayons X avec couche d'oxide

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2201979C3 (de) * 1972-01-17 1979-05-03 Siemens Ag, 1000 Berlin Und 8000 Muenchen Verfahren zur Herstellung einer geschwärzten Schicht auf Drehanoden von Röntgenröhren
NL7312945A (nl) * 1973-09-20 1975-03-24 Philips Nv Draaianode voor een roentgenbuis en werkwijze voor de vervaardiging van een dergelijke anode.
AT337314B (de) * 1975-06-23 1977-06-27 Plansee Metallwerk Rontgenanode
AT376064B (de) * 1982-02-18 1984-10-10 Plansee Metallwerk Roentgenroehren-drehanode
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
US4953190A (en) * 1989-06-29 1990-08-28 General Electric Company Thermal emissive coating for x-ray targets

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2381834A1 (fr) * 1977-02-16 1978-09-22 Gen Electric Anode perfectionnee pour tube a rayons x
US4870672A (en) * 1987-08-26 1989-09-26 General Electric Company Thermal emittance coating for x-ray tube target
EP0421521A2 (fr) * 1989-10-02 1991-04-10 Metallwerk Plansee Gesellschaft M.B.H. Anode pour tube à rayons X avec couche d'oxide

Also Published As

Publication number Publication date
JPH04267040A (ja) 1992-09-22
US5199059A (en) 1993-03-30

Similar Documents

Publication Publication Date Title
DE2805154C2 (de) Röntgenröhren-Anode und Verfahren zu deren Herstellung
DE69013240T2 (de) Thermischer Emissionsüberzug für Röntgenröhren-Targets.
DE3303529C2 (fr)
DE2621067A1 (de) Roentgenanode
EP0399621B1 (fr) Composite de graphite et d'un métal à haut point de fusion
DE2610993A1 (de) Roentgenanode und verfahren zu ihrer herstellung.
DE19522331A1 (de) Verfahren zum Beschichten mindestens eines Werkstückes, Anlage hierfür sowie Verfahren zum Betrieb einer kathodischen Bogenentladung und Verwendung desselben
DE3150591A1 (de) Verfahren zur herstellung von metallueberzuegen durch zerstaeubungsionenbeschichtung
EP0421521B1 (fr) Anode pour tube à rayons X avec couche d'oxide
US4600659A (en) Emissive coating on alloy x-ray tube target
EP0487144A1 (fr) Anode pour tube à rayons X munie d'une couche d'oxyde
EP0385283B1 (fr) Procédé de revêtement d'un substrat en métal dur et outil en métal dur produit par ce procédé
EP0488450B1 (fr) Anode pour tube à rayons X à couche d'oxyde
EP0757370B1 (fr) Tube à décharge électrique ou lampe à décharge et cathode à réserve comprenant du scandate
DE69718363T2 (de) Thermionische Kathode und Verfahren zu ihrer Herstellung
DE68916542T2 (de) Elektrode für entladungslichtquelle.
EP0168736B1 (fr) Anode tournante à revêtement de surface pour tubes à rayons X
DE69409306T2 (de) Thermisch emittierende Kathode, Herstellungsverfahren einer solchen thermisch emittierende Kathode und Elektronenstrahl-Gerät
DE10320700A1 (de) Vakuumgehäuse für eine Röntgenröhre
DE3780246T3 (de) Drahtförmige Glühkathode.
DE19828729B4 (de) Scandat-Vorratskathode mit Barium-Calcium-Aluminat-Schichtabfolge und korrespondierende elektrische Entladungsröhre
EP4121986B1 (fr) Céramique à émission électronique
DE2722668A1 (de) Verfahren zum herstellen duenner schichten aus hochtemperaturfesten metallen wie wolfram, molybdaen, rhenium oder osmium
DE1913793A1 (de) Drehanode fuer Roentgenroehre und Bearbeitungsverfahren hierzu
DE2738207A1 (de) Basismetallplattenwerkstoff fuer eine direkt erhitzte oxidkathode

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: A1

Designated state(s): CH DE FR GB IT LI NL

17P Request for examination filed

Effective date: 19920408

17Q First examination report despatched

Effective date: 19940727

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: PLANSEE AKTIENGESELLSCHAFT

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19950718