EP2194564B1 - Ensemble cible de rayons X et son procédé de fabrication - Google Patents

Ensemble cible de rayons X et son procédé de fabrication Download PDF

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Publication number
EP2194564B1
EP2194564B1 EP08253881.0A EP08253881A EP2194564B1 EP 2194564 B1 EP2194564 B1 EP 2194564B1 EP 08253881 A EP08253881 A EP 08253881A EP 2194564 B1 EP2194564 B1 EP 2194564B1
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EP
European Patent Office
Prior art keywords
substrate
barrier layer
heat sink
ray target
ray
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EP08253881.0A
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German (de)
English (en)
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EP2194564A1 (fr
Inventor
David S.K. Lee
John E. Postman
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Varian Medical Systems Inc
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Varian Medical Systems Inc
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    • 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
    • H01J35/108—Substrates for and bonding of emissive target, e.g. composite structures
    • 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
    • H01J2235/081—Target material
    • 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
    • H01J2235/083—Bonding or fixing with the support or substrate
    • H01J2235/084—Target-substrate interlayers or structures, e.g. to control or prevent diffusion or improve adhesion

Definitions

  • the present invention relates generally to x-ray systems, devices, and related components. More particularly, embodiments of the invention relate to brazed x-ray target assemblies that include an oxide dispersion strengthened (ODS) alloy substrate and a carbon-based heat sink and methods for manufacturing such x-ray target assemblies and related devices.
  • ODS oxide dispersion strengthened
  • An x-ray tube typically includes a cathode assembly and an anode assembly disposed within an evacuated enclosure.
  • the cathode assembly includes an electron source and the anode assembly includes a target surface that is oriented to receive electrons emitted by the electron source.
  • an electric current is applied to the electron source, which causes electrons to be produced by thermionic emission.
  • the electrons are then accelerated toward the target surface of the anode assembly by applying a high-voltage potential between the cathode assembly and the anode assembly.
  • the kinetic energy of the electrons causes the production of x-rays.
  • Some of the x-rays so produced ultimately exit the x-ray tube through a window in the x-ray tube, and interact with a material sample, patient, or other object.
  • Stationary anode x-ray tubes employ a stationary anode assembly that maintains the anode target surface stationary with respect to the stream of electrons produced by the cathode assembly electron source.
  • rotary anode x-ray tubes employ a rotary anode assembly that rotates portions of the anode's target surface into and out of the stream of electrons produced by the cathode assembly electron source.
  • the target surfaces of both stationary and rotary anode x-ray tubes are generally angled, or otherwise oriented, so as to maximize the amount of x-rays produced at the target surface that can exit the x-ray tube via a window in the x-ray tube.
  • the target has previously consisted of a disk made of a refractory metal such as tungsten, and the X-rays are generated by making the electron beam collide with this target, while the target is being rotated at high speed. Rotation of the target is achieved by driving the rotor provided on a support shaft extending from the target.
  • a refractory metal such as tungsten
  • Increasing the power levels of the x-ray tube is typically accompanied by an increase in the operating temperatures of the anode, which, if high enough, may result in deformation of the molybdenum alloy substrate.
  • Deformation in the substrate can cause large stresses in the metallurgical bond between the alloy substrate and the graphite heat sink. Should the stress exceed a threshold value, a complete debond of the graphite heat sink can result. The magnitude of this stress imposes a limit on the maximum size, rotational speed and highest allowable temperature of the alloy substrate.
  • Oxide dispersion strengthened (ODS) Mo alloys currently show promising performance for reducing deformation of the substrate at high temperatures.
  • US 2007/0119907 A1 discloses that a composite body which can withstand high thermal stresses is formed by high-temperature soldering at least a part of a high-temperature-resistant, metallic or nonmetallic component and at least a part of a high-temperature-resistant, nonmetallic component.
  • a metallic barrier layer which is impervious to the solder melt, of one or more elements selected from the group consisting of V, Nb, Ta, Cr, Mo, W, Ti, Zr, Hf and alloys thereof, is deposited on that surface of each nonmetallic component which is to be soldered.
  • US 2003/0006269 A1 discloses that a reaction-brazing of tungsten or molybdenum metal bodies to carbonaceous supports enables an x-ray generating anode to be joined to a preferred lightweight substrate.
  • Complementary surfaces are provided on a dense refractory metal body and a graphite or a carbon-carbon composite support.
  • a particulate braze mixture comprising Hf or Zr carbide, Mo or W boride, Hf or Zr powder and Mo or W powder is coated onto the support surface, and hafnium or zirconium foil may be introduced between the braze mixture and the refractory metal body complementary surface.
  • Reaction-brazing is carried out in a single step at or near the eutectic point of the components, which may be influenced to some extent by the presence of carbon and boride.
  • the present invention provides an x-ray target assembly, a method for manufacturing an x-ray target assembly, an x-ray tube and a high performance CT-scanner as defined in the claims.
  • Embodiments of the invention concern x-ray target assemblies for use as an anode in an x-ray device.
  • the x-ray target assemblies of the embodiments have an oxide dispersion strengthened (ODS) refractory metal alloy substrate (e . g ., ODS Mo alloy) that is bonded to a carbon-containing heat sink. Good bonding between the substrate and the heat sink is achieved by placing an oxide-free barrier layer between the ODS metal substrate and the heat sink.
  • ODS oxide dispersion strengthened
  • the oxide-free barrier layer advantageously minimizes or eliminates chemical reactions that would otherwise be possible between the dispersed oxides and the carbon-based heat sink during the manufacturing process. Preventing these undesired reactions while manufacturing the x-ray target assembly yields a device with improved bonding between the heat sink and the substrate, compared to devices manufactured without the barrier layer.
  • the present invention includes a method for manufacturing an x-ray target assembly having an ODS refractory metal substrate.
  • the method includes (i) providing an ODS refractory metal substrate (e . g ., ODS Mo alloy), (ii) forming a barrier layer on the substrate, and (iii) brazing a carbon-containing heat sink to the barrier layer.
  • ODS refractory metal substrate e . g ., ODS Mo alloy
  • the substrates used in the x-ray targets of the invention can be made of any molybdenum or molybdenum alloy that has an oxide dispersed throughout to improve the thermal stability and/or strength of the alloy.
  • the primary metal component of the substrate is molybdenum or molybdenum alloyed with a proper amount of rhenium, titanium, zirconium, niobium, tantalum, hafnium, vanadium, or tungsten.
  • the amount of alloying element can vary depending on solution strengthening effect of the element.
  • the ODS refractory metal alloy includes one or more oxides dispersed throughout the substrate to achieve the desired thermal stability and strength.
  • suitable oxide compounds that can be dispersed in the refractory metal include, but are not limited to, lanthana (La 2 O 3 ), yttria (Y 2 O 3 ), ceria (CeO 2 ), thoria (ThO 2 ), and combinations of these.
  • the oxide can be included in the refractory metal in a range from about 0.1 wt% to about 10 wt%, more preferably in a range from about 1 wt% to about 6 wt%, and most preferably in a range from about 2 wt% to about 4 wt% depending on production capability and performance requirements.
  • the barrier layer is a thin layer of metal coated on the substrate to prevent the oxides in the substrate from reacting with carbon in the heat sink during brazing.
  • the material used to make the barrier layer is selected to be substantially free of the oxides in the substrate, and preferably free of any oxides.
  • the barrier layer can be substantially pure Mo, Ta, Re, W, Ti, Nb, V, Hf, Zr, or a Mo alloy of these.
  • the barrier layer can be a carbide, nitride, boride, or silicide of these metals.
  • the barrier layer can be coated ( i . e ., formed) on the substrate using a deposition technique or a mechanical technique or other similar technique.
  • the barrier layer is deposited on the substrate using plasma spray coating, salt-bath electrodeposition, electroplating, vacuum sputtering, melt evaporation, chemical vapor deposition, or a similar technique.
  • the barrier layer can be metallurgically bonded to the substrate using hot rolling, cold rolling, upset forging, hot isostatic pressing, cold isostatic pressing, or a similar technique.
  • the thickness of the barrier layer (e . g ., Mo) is in a range from about 0.1 mm to about 1.5 mm, and most preferably in a range from about 0.25 mm to about 1 mm.
  • the carbon-containing heat sink is brazed to the substrate to form the target assembly. Any type of thermally conductive carbon-based heat sink can be used. Graphitic and/or composite carbon heat sinks are preferred for their durability and ability to conduct heat away from the substrate during use.
  • the heat sink can be brazed to the barrier layer using a braze that is compatible with the particular heat sink being used and the particular metals in the barrier layer.
  • suitable brazes include, but are not limited to, Zr, Ti, V, Cr, Fe, Co, Ni, Pt, Rd, and Pd.
  • the x-ray target devices manufactured using the method of the present invention have surprisingly good bonding between the heat sink and the substrate compared to similar devices manufactured without a barrier layer. It is believed that the superior bonding in the x-ray target assemblies of the invention is achieved by reducing or eliminating the production of carbon oxide gases during the brazing process.
  • the barrier layer keeps oxides in the ODS refractory metal away from the carbon heat sink during the brazing process, thereby preventing the oxides from reacting with carbon to form a gaseous carbon oxide. Preventing the formation of gases during brazing improves the quality of bonding.
  • Figures 1-3 depict various features of embodiments of the present invention, which is generally directed to an x-ray tube device having a high performance rotating anode.
  • the x-ray target assembly 100 includes a target substrate 110 that is formed from an oxide dispersed strengthened molybdenum alloy.
  • a stem 112 is integrally formed with the target substrate 110.
  • a target focal track 114 is formed on the upper surface of the target substrate.
  • Focal track 114 is typically made of a tungsten-rhenium alloy, although other materials can also be used. Electrons generated by a cathode (not shown) impinge on the focal track 114.
  • the X-ray emitting metal of focal track 114 emits X-rays in response to the impingement of electrons.
  • the target substrate 110 is backed by a heat sink 116, which is bonded to the substrate through various layers, which are discussed more fully below. Heat produced from the impingement of the electrons is mostly dissipated through heat sink 116.
  • substrate 110 and focal track 114 can be shaped like a disk to facilitate high speed rotation.
  • the anode assembly 100 is rotated by an induction motor, which drives bearing sleeve 119 and bearing shaft 118.
  • Bearing shaft 118 is connected to stem 112 and rotatably supported by bearings 120.
  • Bearings 120 are housed in bearing housing 122, which supports the x-ray target assembly 100.
  • the anode and cathode assemblies are sealed in a vacuum envelope.
  • the stator portion of the motor is typically provided outside the vacuum envelope.
  • the x-ray tube can is enclosed in a casing having a window for the X-rays that are generated to escape the tube.
  • the casing can be filled with oil to absorb heat produced as a result of x-ray generation.
  • Figure 3 shows a portion of the x-ray target assembly, illustrating substrate 110 and the heat sink 116 in greater detail and showing the interlayers that bond substrate 110 to the heat sink 116.
  • x-ray target assembly 100 includes a barrier layer 124 and a braze layer 126.
  • Barrier layer 124 is positioned between substrate 110 and heat sink heat sink 116 to prevent chemical reactions between substrate 110 and heat sink 116 during brazing. The following describes the substrate, heat sink, and interlayers in more detail.
  • Substrate 110 can have any shape suitable for use in an x-ray tube. To facilitate rotation, the substrate is preferably disk-like. The thickness of the substrate and shape is selected to maximize strength, heat dissipation, and ease of manufacturing while minimizing cost. In one embodiment, the substrate is substantially disk shaped and has a thickness in a range from about 10 mm to about 14 mm. Substrate 110 can be made from any oxide-dispersed-strengthened refractory metal (ODS refractory metal). In a preferred embodiment, the primary refractory metal is Mo. Molybdenum-based substrates have yielded exceptionally good substrates for use in rotating anode x-ray tubes.
  • ODS refractory metal oxide-dispersed-strengthened refractory metal
  • Molybdenum-based substrates have yielded exceptionally good substrates for use in rotating anode x-ray tubes.
  • the substrate includes one or more inert metal oxides that are dispersed as fine particles throughout the refractory metal.
  • suitable metal oxides that can be dispersed in the refractory metal include lanthana, yttria, ceria, and thoria, with lanthana being preferred.
  • the metal oxide compounds can be included in the refractory metal in any amount that yields a strengthened refractory metal substrate.
  • the weight percent of the metal oxide (e . g ., La) in the ODS refractory metal is in a range from about 0.1 wt% to about 10 wt%, more preferably in a range from about 1.0 wt% to about 6 wt%, and most preferably in a range from about 2 wt% to about 4 wt%.
  • the grain size of the ODS refractory metal and the particle size of the metal oxides can have an effect on the properties of the substrate.
  • the grain size is in a range from about 10 to about 50 micrometers and the average diameter of the oxide particles is in a range from about 0.05 micrometers to about 5 micrometers.
  • the ODS refractory metals can be manufactured using any suitable method.
  • the ODS refractory metal can be manufactured by using the following steps: (a) forming a slurry of molybdenum oxide and an aqueous solution of a metal salt selected from nitrates or acetates of lanthanum, cerium, thorium, or yttria; (b) heating the slurry in a hydrogen atmosphere to produce a powder of molybdenum and the oxides of the metal salt; (c) mixing and cold isostatically pressing the powder; (d) sintering the powder from step (c) in a hydrogen atmosphere to produce a sintered product; and (e) thermomechanically processing the sintered product to a total reduction in cross-sectional area of about 60% to about 80% or even higher to produce about a 93%-99% dense molybdenum alloy containing an oxide dispersion.
  • the ODS refractory metals are typically provided as a powder.
  • Substrate 110 can be manufactured from the powders using known powder metallurgy techniques.
  • the heat sink 116 is a carbon-based structure positioned on the substrate 110 so as to absorb heat generated from electrons impinging upon focal track 114, to create x-rays.
  • Heat sink 116 is made of a thermoconductive material such as, but not limited to, graphite or thermally conductive carbon composite. During use, the heat sink absorbs thermal energy from the substrate and dissipates the heat.
  • the heat sink can have any shape or size so long as the heat sink adequately dissipates heat and is suitable for rotating anodes. Typically the heat sink is disk-shaped to facilitate high speed rotation.
  • the surface of the heat sink that faces the substrate can have a regular or irregular pattern of grooves to enhance the surface area that bonds with the substrate. In one embodiment, the pattern comprises concentric or phonographic grooves.
  • the barrier layer is a thin layer of a metal compound that separates the ODS refractory metal from the carbon-based heat sink.
  • the barrier layer material is substantially free of the metal oxides that are present in the substrate and is preferably free of any oxides.
  • the barrier layer can be made from a substantially pure metal. Examples of suitable metals include Mo, Ta, Re, W, Ti, Nb, V, Hf, Zr, and combinations of these. These compounds can also be used in combination with boron, silicon, nitrogen, or carbon in the form of metal borides, nitrides, silicides, carbides, or combinations of these. Where a metal carbide is used as the barrier layer, the surface of the substrate can be chemically etched before depositing the carbide so as to remove oxides from the surface of the substrate, thereby preventing the oxides from reacting with the carbide.
  • the barrier layer is made very thin to minimize the effect that the barrier layer has on the overall mechanical and chemical properties of the substrate. Since the barrier layer does not include the dispersed oxides, the barrier layer does not have some of the same properties as the oxide containing portion of the substrate. By using a thin layer, the overall properties of the substrate can retain the strength and thermal properties of the substrate.
  • the barrier layer has a thickness in a range from about 0.1 mm to about 1.5 mm, and most preferably in a range from about 0.25 mm to about 1.0 mm.
  • the braze layer is a layer of metal that bonds the surface of the carbon-containing heat sink to the substrate.
  • the braze layer is formed by brazing ( i . e ., melting) a brazing material.
  • the braze layer takes the shape of the surface of the heat sink.
  • the heat sink has concentric rings or another grooved pattern that the braze layer fills to provide high surface area contact.
  • the braze layer is made from any brazing material compatible with brazing the carbon-based heat sink to the barrier layer.
  • the brazing material is typically selected to have a melting point that is below that of the substrate.
  • the braze material and a component of the barrier layer form a diffused boundary.
  • the diffused boundary can be formed by selecting a braze that melts at a temperature similar to at least one metal component in the barrier material.
  • the braze and the barrier material form a eutectic during brazing. Examples of suitable brazing materials include Zr, Ti, V, Cr, Fe, Co, Ni, Pt, Rd, and Pd.
  • Embodiments of the invention also include methods for manufacturing an anode assembly.
  • Methods for manufacturing the anode assembly according to the invention generally include (i) providing an x-ray target substrate having a deposited track, (ii) forming a barrier layer on at least a portion of the substrate on the opposite side as the track, and (iii) brazing a carbon-containing heat sink to the substrate.
  • the substrate can be provided in powder form or as a manufactured and/or machined piece.
  • the manufacturing process of the invention yields a solidified solid structure having the desired shape ( e . g ., a disk shaped solid).
  • the barrier layer is formed on at least a portion of the substrate.
  • the barrier layer covers the entire surface where the heat sink is to be attached.
  • the barrier layer can cover the entire substrate ( e . g ., a W or W-Re substrate).
  • the barrier layer is formed on the substrate by either depositing a barrier layer material or by mechanically bonding a thin layer of barrier material to the substrate.
  • suitable materials that can be deposited or mechanically bonded to the substrate include pure metals, borides, nitrides, silicides, or carbides of Mo, Ta, Re, W, Ti, Nb, V, Hf, Zr, and combinations of these.
  • any deposition technique compatible with the barrier layer materials can be used.
  • suitable deposition techniques include plasma spray coating, salt-bath electrodeposition, electroplating, vacuum sputtering, melt evaporation, chemical or physical vapor deposition, or a combination of these.
  • the deposition technique is carried out so as to deposit the barrier layer material in the desired location and with a desired thickness.
  • Those skilled in the art are familiar with the use of the foregoing techniques to deposit thin or thick layers of metals.
  • a carbide is used as the barrier material
  • a mechanical technique can be used to form the barrier layer.
  • mechanical techniques that can be used to form the barrier layer include hot rolling, cold rolling, upset forging, hot isostatic pressing, cold isostatic pressing, and combinations thereof.
  • the barrier material can be provided as a thin sheet that is pressed onto the substrate.
  • the barrier layer can be formed while simultaneously forming the substrate from a powder ODS refractory metal.
  • a three-dimensional piece of barrier material e . g ., a can
  • the substrate is then formed inside the barrier material using a technique such as isostatic pressing.
  • the barrier material encapsulates the substrate. If desired, the barrier material can be machined or otherwise worked to remove a portion of the barrier material.
  • the carbon heat sink is brazed to the substrate ( i . e ., to the barrier layer on the substrate).
  • the braze can be Ti, Zr, or a compound thereof.
  • the barrier layer material, braze material, brazing temperature, and thickness of the barrier layer are selected to ensure that the braze will form a melt and bond the heat sink to the barrier layer, while preventing oxides in the ODS metal from coming into contact with the carbon substrate.
  • the braze and barrier material can be selected such that the brazing temperature is below the melting point of the barrier material.
  • the barrier material has a melting point in a range from about 1600 °C to about 2000 °C, alternatively in a range from about 1700 °C to about 1900 °C. In some cases the melting point of the barrier layer can be in a range between about 2000 °C and 3900 °C ( e . g ., for W or TaC or ZrC materials).
  • the type of barrier material used can also affect the temperature need during brazing.
  • the materials are selected to form a eutectic, thereby allowing for brazing at relatively low temperatures.
  • the barrier material is a boride, nitride, silicide, or carbide
  • the brazing temperature may need to be close to the melting point of the braze.
  • the particular barrier material selected should be thermodynamically stable above the melting point of the braze.
  • the barrier material can be selected to be stable at a temperature above 1850 °C, the melting point of Zr.
  • the barrier material provides a physical barrier between the carbon atoms in the heat sink and the oxides in the ODS refractory metal of the substrate.
  • the barrier material provides a physical barrier between the carbon atoms in the heat sink and the oxides in the ODS refractory metal of the substrate.
  • a barrier layer that is substantially free of oxides, there are no oxides available to migrate through the braze to the boundary with the carbon heat sink when the braze is molten.
  • carbon radicals diffuse from the boundary with the carbon heat sink to the boundary with the barrier layer, there will be no oxides that can form carbon oxide gases.
  • the braze is able to form a good bond with the carbon heat sink and allows for a higher performance anode to be built.
  • the target has a diameter of at least about 100 mm, more preferably at least about 150 mm and most preferably at least about 200 mm. Of course smaller diameters such as from 25-100 mm are also possible. Larger diameter targets are useful for making higher performance x-ray tubes.
  • An x-ray target assembly was manufactured from a substrate comprising an ODS Mo alloy.
  • the ODS Mo alloy included 1 wt% La 2 O 3 dispersed in Mo.
  • the substrate was disk-shaped with an approximately 200 mm diameter.
  • a W-Re track was deposited on the upper side of the substrate using a vacuum plasma spray process.
  • a substantially pure Mo barrier layer of about 0.25 mm to 1 mm was deposited on the substrate using a vacuum plasma spray process.
  • FIG. 4 is a high resolution picture of a cross section of the x-ray target assembly. The cross section was achieved by fracturing the substrate and heat sink. The specimen shows excellent brazing between the substrate and the carbon heat sink as evidenced by the Zr-Mo-C (ternary alloy) brazed layer with no bubbles within the well-defined "saw-tooth like" outline on the graphite side ( i . e ., cross-section of record groove) and straight boundary with the Mo barrier.
  • Zr-Mo-C ternary alloy
  • targets manufactured the same way except without a barrier layer showed significant spacing at the boundary between the braze and the heat sink, which resulted in debonded areas and poor performance of heat conduction into the heat sink. It is believed that the poor bonding in the devices made without the barrier layer was due to the formation of carbon oxide gas bubbles that prevented good bonding between the graphite and the ODS substrate.
  • FIG. 5 illustrates an x-ray tube 200 that includes an outer housing 202, within which is disposed an evacuated enclosure 204. Disposed within evacuated enclosure 204 is a cathode 208 and a rotating anode 100, manufactured according to the present invention. Anode 100 is spaced apart from and oppositely disposed to cathode 208. Anode 100 is rotatably supported by bearing assembly 120.
  • cathode 208 is biased by a power source (not shown) to have a large negative voltage, while anode 100 is maintained at ground potential. In other embodiments, the cathode is biased with a negative voltage while the anode is biased with a positive voltage.
  • Cathode 208 includes at least one filament 214 that is electrically connected to a high-voltage source. During operation, electrical current is passed through the filament 214 to cause electrons, designated at 218, to be emitted from cathode 208 by thermionic emission. Application of the high-voltage differential between anode 100 and cathode 208 then causes electrons 218 to accelerate from cathode filament 214 toward a focal track 114 that is positioned on a target surface of rotating anode 100.
  • x-ray transmissive window 224 disposed in outer housing 202.
  • Window 224 is comprised of an x-ray transmissive material so as to enable the x-rays to pass through window 224 and exit x-ray tube 200.
  • the x-rays exiting the tube 100 can then be directed for penetration into an object, such as a patient's body during a medical evaluation, or a sample for purposes of materials analysis.
  • the high performance and/or larger diameters of the x-ray target assemblies of the present invention make the x-ray target assemblies of the invention particularly suitable for use in high performance devices such as CT-scanners.
  • CT-scanners incorporating the x-ray tubes of the invention can achieve higher intensity x-rays that allow for higher resolution spectroscopy.
  • the CT-scanners of the invention can be made to detect material features that might not otherwise be possible with x-ray tubes having inferior performance.
  • the improved bonding of the heat sink to the substrate improves the durability of the device, thereby lowering operating costs and/or avoiding downtime for repairs or maintenance.

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Claims (17)

  1. Ensemble de cible pour rayons X devant être utilisé dans un jeu d'anode rotative, comprenant :
    un substrat (110) contenant un métal réfractaire et un ou plusieurs composés d'oxyde dispersés dans le métal réfractaire ;
    un puits thermique (116) contenant du carbone ;
    une couche barrière (124) ayant une épaisseur dans une fourchette d'environ 0,1 millimètre à environ 1,5 millimètre, la couche barrière (124) étant liée au substrat (110) de sorte qu'elle soit positionnée entre le substrat (110) et le puits thermique (116), la couche barrière (124) étant sensiblement exempte d'un ou de plusieurs composés oxydes qui sont dispersés dans le métal réfractaire ; et
    une couche de brasure (126) ;
    caractérisé en ce que la couche barrière (124) est directement liée au substrat (110) et en ce que la couche de brasure (126) est positionnée directement entre le puits thermique (116) et la couche barrière (124) de sorte que la couche barrière (124) et le puits thermique (116) sont brasées directement ensemble par la couche de brasure.
  2. Ensemble de cible pour rayons X selon la revendication 1, dans lequel la couche barrière (124) :
    est fabriquée en un métal sensiblement pur, ou
    est fabriquée en un métal sensiblement pur de Mo, Ta, Re, W, Ti, Nb, V, Hf ou Zr, ou une combinaison de ceux-ci, ou
    comprend :
    un borure de Mo, Ta, Re, W, Ti, Nb, V, Hf ou Zr,
    un siliciure de Mo, Ta, Re, W, Ti, Nb, V, Hf ou Zr,
    un nitrure de Mo, Ta, Re, W, Ti, Nb, V, Hf ou Zr,
    un carbure de Mo, Ta, Re, W, Ti, Nb, V, Hf ou Zr,
    une combinaison de ceux-ci.
  3. Ensemble de cible pour rayons X selon la revendication 1 ou 2, dans lequel la couche barrière (124) possède une épaisseur dans une fourchette d'environ 0,25 à environ 1,0 mm.
  4. Ensemble de cible pour rayons X selon la revendication 1, 2 ou 3, dans lequel la couche de brasure (126) contient le Zr, Ti, V, Cr, Fe, Co, Ni, Pt ou Pd.
  5. Ensemble de cible pour rayons X selon la revendication 1, 2, 3 ou 4, dans lequel le substrat (1 10) a une forme de disque et comprend également une voie de cible circulaire autour de la périphérie du substrat.
  6. Ensemble de cible pour rayons X selon l'une quelconque des revendications 1 à 5, dans lequel le métal réfractaire est le molybdène ou un alliage de molybdène.
  7. Ensemble de cible pour rayons X selon l'une quelconque des revendications 1 à 6, dans lequel le composé d'oxyde comprend le lanthane, l'yttrium, la cérine, la thorine, ou une combinaison de ceux-ci.
  8. Procédé de fabrication d'un ensemble de cible pour rayons X, comprenant :
    l'utilisation d'un substrat (110) contenant un métal réfractaire et un ou plusieurs composés d'oxyde dispersés dans le métal réfractaire ;
    la formation d'une piste cible (114) sur le substrat (110) ;
    la formation d'une couche barrière (124) ayant une épaisseur dans une fourchette d'environ 0,1 millimètre à environ 1,5 millimètre sur au moins une partie du substrat (110) de sorte que la couche barrière (124) est liée au substrat (110), la couche barrière (124) comprenant un matériau qui est sensiblement exempt d'un ou de plusieurs composés d'oxyde dispersés dans le métal réfractaire ; et
    caractérisé en ce que la couche barrière (124) est directement liée au substrat (110), et en ce que, après l'étape de formation de la barrière (124), un puits thermique (116) à base de carbone est directement brasé à la couche barrière (124) avec une brasure (126).
  9. Procédé selon la revendication 8, dans lequel le métal réfractaire est du molybdène ou un alliage de molybdène.
  10. Procédé selon les revendications 8 ou 9, dans lequel le composé d'oxyde comprend du lanthane, de l'yttrium, de la cérine, de la thorine, ou une combinaison de ceux-ci.
  11. Procédé selon les revendications 8, 9, ou 10 dans lequel le puits thermique (116) contient du graphite ou un composite de carbone.
  12. Procédé selon les revendications 8, 9, 10 ou 11 dans lequel la couche barrière (124) contient du Mo, Ta, Re, W, Ti, Nb, V, Hf, Zr, ou des combinaisons de ceux-ci.
  13. Procédé selon la revendication 8, dans lequel le substrat (110) comprend un alliage de Mo renforcé par une dispersion d'oxyde (ODS) et dans lequel la couche barrière (124) est un métal sensiblement pur ou un alliage de métal choisi dans le groupe composé de Mo, Ta, Re, W, Ti, Nb, V, Hf, Zr ou un alliage Mo de ceux-ci, et le procédé comprenant le dégazage du substrat recouvert par la couche barrière (124) et la brasure d'un disque en graphite au substrat recouvert dégazé en utilisant une brasure contenant du Zr, Ti, V, Cr, Fe, Co, Ni, Pt ou du Pd.
  14. Procédé selon l'une quelconque des revendications 8 à 13, dans lequel la couche barrière (124) est déposée sur le substrat (110) à l'aide d'une technique choisie dans le groupe composé d'un revêtement par jet de plasma, l'électrodéposition par bain de sel, la galvanoplastie, la pulvérisation à vide, l'évaporation par fusion, le dépôt chimique en phase vapeur, le dépôt physique en phase vapeur, ou une combinaison de ceux-ci.
  15. Procédé selon l'une quelconque des revendications 8 à 14, dans lequel la couche barrière (124) est collée mécaniquement ou liée métallurgiquement au substrat (110) avec une technique choisie dans le groupe composé de laminage à chaud, laminage à froid, refoulage, pressage hydrostatique à chaud, pressage hydrostatique à froid et des combinaisons de ceux-ci.
  16. Un tube à rayons X comprenant la cible à rayons X de l'une quelconque des revendications 1 à 7 ou une cible à rayons X fabriquée selon le procédé de l'une quelconque des revendications 8 à 12.
  17. Tomodensitogramme à haute performance comprenant un tube à rayons X ou une cible à rayons X selon la revendication 16.
EP08253881.0A 2008-12-04 2008-12-04 Ensemble cible de rayons X et son procédé de fabrication Not-in-force EP2194564B1 (fr)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002105552A (ja) * 2000-10-02 2002-04-10 Nikko Materials Co Ltd 高純度ジルコニウム又はハフニウム及びこれらの製造方法

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT386612B (de) 1987-01-28 1988-09-26 Plansee Metallwerk Kriechfeste legierung aus hochschmelzendem metall und verfahren zu ihrer herstellung
AT393651B (de) * 1990-06-28 1991-11-25 Plansee Metallwerk Hochtemperaturbestaendiger verbundkoerper
US5868876A (en) 1996-05-17 1999-02-09 The United States Of America As Represented By The United States Department Of Energy High-strength, creep-resistant molybdenum alloy and process for producing the same
US6400800B1 (en) * 2000-12-29 2002-06-04 Ge Medical Systems Global Technology Company, Llc Two-step brazed x-ray target assembly
US6554179B2 (en) * 2001-07-06 2003-04-29 General Atomics Reaction brazing of tungsten or molybdenum body to carbonaceous support
US6707883B1 (en) 2003-05-05 2004-03-16 Ge Medical Systems Global Technology Company, Llc X-ray tube targets made with high-strength oxide-dispersion strengthened molybdenum alloy
AT6994U1 (de) * 2003-10-03 2004-07-26 Plansee Ag Verfahren zur herstellung eines verbundkörpers

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002105552A (ja) * 2000-10-02 2002-04-10 Nikko Materials Co Ltd 高純度ジルコニウム又はハフニウム及びこれらの製造方法

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