Method for manufacturing a nuclear fuel rod cladding and corresponding nuclear fuel rod cladding

Abstract

Method for manufacturing a nuclear fuel rod cladding and corresponding nuclear fuel rod cladding. The manufacturing process is intended for the manufacture of a nuclear fuel rod cladding (4) comprising a substrate (14) covered with a protective coating (16). The manufacturing process includes supplying the substrate (14) and depositing the protective coating (16) onto the substrate (14) by sputtering physical vapor deposition, simultaneously employing several different sputtering physical vapor deposition techniques. Figure for the abstract: Figure 2

Description

Title of the invention: Method for manufacturing a nuclear fuel rod cladding and corresponding nuclear fuel rod cladding

[0001] The present invention relates to the field of nuclear fuel rod cladding (hereinafter also referred to as "cladding") intended to contain nuclear fuel.

[0002] Nuclear fuel including fissile material is generally contained in a cladding which prevents the dispersion of the nuclear fuel.

[0003] Nuclear fuel assemblies used in light water or heavy water reactors generally comprise a bundle of nuclear fuel rods, each nuclear fuel rod comprising a tubular cladding containing nuclear fuel, the cladding being hermetically sealed at each of its two ends by a plug.

[0004] Nuclear fuel rod cladding is made, for example, of zirconium-based alloys. Such zirconium-based alloys exhibit high performance under normal operating conditions in nuclear reactors.

[0005] However, they can reach their limits, particularly in terms of temperature, during severe accidental conditions, such as during a loss of coolant accident (or LOCA for "Loss Of Coolant Accident").

[0006] During such an event, the temperature in the core of the nuclear reactor can reach more than 800°C, and the cooling fluid is then essentially in the form of water vapor.

[0007] This can cause rapid degradation of the cladding of a nuclear fuel rod, including the release of hydrogen and rapid oxidation of the cladding, leading to its embrittlement or even bursting, and therefore to the release of nuclear fuel from the cladding.

[0008] It is possible to provide a sheath comprising a substrate made of zirconium-based alloy and covered with a protective coating made, for example, of a chromium-based material.

[0009] Such a protective coating generally makes it possible to increase the tolerance of the sheath under normal conditions and under accidental conditions.

[0010] It is possible to manufacture such a sheath by depositing the protective coating on the substrate by physical vapor deposition.

[0011] However, such a technique for depositing the protective coating is relatively slow, especially for significant coating thicknesses.

[0012] The generalization of the use of protective coatings on nuclear fuel cladding at the industrial level requires the ability to carry out the deposition of the protective coating in a sufficiently rapid manner.

[0013] One of the aims of the invention is to propose a method for manufacturing a nuclear fuel cladding having a substrate coated with a protective coating, which can be implemented quickly.

[0014] To this end, the invention proposes a method for manufacturing a nuclear fuel rod cladding comprising a substrate covered with a protective coating, the manufacturing method comprising the supply of the substrate, and the deposition of the protective coating on the substrate by physical vapor deposition by sputtering, by simultaneously implementing several different physical vapor deposition techniques by sputtering.

[0015] The simultaneous implementation of several different physical vapor deposition techniques by cathodic sputtering makes it possible to achieve rapid deposition of the protective coating, obtaining a protective coating with good resistance to the external environment and good adhesion to the substrate.

[0016] “Simultaneous” implementation means that the different physical vapor deposition techniques are implemented together and at the same time, i.e. during the same period of time.

[0017] Different sputtering physical vapor deposition techniques implemented simultaneously can be implemented using at least one cathode common to at least two of the different sputtering physical vapor deposition techniques that are implemented simultaneously and / or at least one cathode dedicated to only one of the different sputtering physical vapor deposition techniques that are implemented simultaneously.

[0018] Each physical vapor phase deposition technique is implemented by applying an excitation signal to the associated cathode, the excitation signal having a periodic pattern, the pattern being for example a plateau, a pulse or a train of pulses.

[0019] The joint implementation of several different physical vapor phase deposition techniques using the same common cathode is for example achieved by combining the excitation signals emitted simultaneously and in a synchronized manner in such a way that their respective patterns are applied sequentially to the common cathode.

[0020] According to particular embodiments, the manufacturing process comprises one or more of the following optional features, taken individually or according to all technically possible combinations:

[0021] - at least two of the different physical vapor deposition techniques sputtering processes are implemented simultaneously using a common cathode;

[0022] - the manufacturing process includes applying to each common cathode a combined excitation signal corresponding to the superposition of at least two elementary excitation signals, each elementary excitation signal being formed of a periodic pattern corresponding to a respective sputtering physical vapor deposition technique among the sputtering physical vapor deposition techniques implemented simultaneously using said common cathode, the elementary excitation signals being synchronized in such a way that their respective patterns are present sequentially in the combined excitation signal;

[0023] - each elementary excitation signal is generated by a signal generator of respective excitation, the elementary excitation signals being synchronized and superimposed to form the combined excitation signal applied to said common cathode;

[0024] - at least one of the physical vapor deposition techniques by spraying cathodic deposition implemented simultaneously is implemented using a dedicated cathode, by applying an excitation signal to this dedicated cathode for the implementation of this physical vapor phase deposition technique;

[0025] - each of the physical vapor deposition techniques by spraying cathodic deposition implemented simultaneously is implemented using a dedicated cathode, by applying an excitation signal to this dedicated cathode for the implementation of this physical vapor phase deposition technique;

[0026] - the excitation signal of each dedicated cathode is generated by a generator of respective excitation signal;

[0027] - physical vapor phase deposition techniques implemented simultaneously are chosen from: high-power pulsed magnetron sputtering (HiPIMS) unipolar or bipolar, unipolar or bipolar direct current (DC) magnetron sputtering, unipolar or bipolar pulsed-DC magnetron sputtering, unipolar or bipolar medium frequency (MF) magnetron sputtering, and unipolar or bipolar radio frequency (RF) magnetron sputtering;

[0028] - the substrate is made of a zirconium-based material and / or the coating of protection is made from a chrome-based material;

[0029] - the thickness of the protective coating after the deposition step is included between 5 pm and 30 pm, especially between 10 pm and 20 pm;

[0030] - the substrate has a shape of revolution around a central axis, the process of manufacturing including rotating the substrate around the central axis during the deposition step;

[0031] - the manufacturing process includes polarizing the substrate during the deposition of the coating.

[0032] The invention also relates to a nuclear fuel rod cladding comprising a substrate covered with a protective coating deposited on the substrate by physical vapor deposition by simultaneously implementing a plurality of different physical vapor deposition techniques by sputtering.

[0033] The invention also relates to a physical vapor deposition installation, the installation comprising a chamber, at least one atmosphere control device for generating a rarefied atmosphere in the chamber, at least one cathode and an excitation device, the installation being configured for the deposition of a protective coating on a substrate introduced into the chamber by simultaneously implementing several different cathodic sputtering physical vapor deposition techniques using the cathode(s).

[0034] According to particular embodiments, the installation comprises one or more of the following optional features, taken individually or in all technically possible combinations:

[0035] - the installation includes at least one common cathode for implementation if simultaneous of at least two of the sputtering physical vapor deposition techniques implemented simultaneously, the excitation device being configured to generate a combined common cathode excitation signal corresponding to the superposition of several elementary excitation signals, each elementary excitation signal having a periodic pattern corresponding to a respective of the sputtering physical vapor deposition techniques implemented simultaneously using said common cathode, the elementary excitation signals being combined in such a way that their respective patterns are present sequentially in the combined excitation signal;

[0036] - the installation includes at least one dedicated cathode for the implementation of a among the sputtering physical vapor deposition techniques implemented simultaneously, the excitation device being configured to generate a respective excitation signal for each dedicated cathode, the excitation signal corresponding to the sputtering physical vapor deposition technique associated with that dedicated cathode.

[0037] - the installation is configured for substrate polarization during re deposition garment.

[0038] The invention and its advantages will be better understood from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings, in which:

[0039] - [Fig. 1] [Fig. 1] is a schematic longitudinal cross-sectional view of a pencil nuclear fuel with a cladding;

[0040] - [Fig.2] [Fig.2] is a schematic cross-sectional view of the sheath of the nuclear fuel rod of the [Fig.1];

[0041] - [Fig.3] [Fig.3] is a schematic view of a re-deposit installation garment on a substrate by physical vapor deposition by sputtering, comprising a cathode common to two physical vapor deposition techniques by sputtering implemented simultaneously.

[0042] - [Fig.4] [Fig.4] contains graphs illustrating the realization of a signal combined excitation for the excitation of a cathode for the implementation of a physical vapor phase deposition by cathodic sputtering;

[0043] - [Fig. 5] [Fig. 5] contains graphs illustrating the realization of a signal combined excitation for the excitation of a cathode for the implementation of a physical vapor phase deposition by cathodic sputtering;

[0044] - [Fig.6] [Fig.6] is a schematic view of another re-deposit installation garment on a substrate by physical vapor deposition by sputtering, the installation comprising two dedicated cathodes, each intended for the implementation of a respective physical vapor deposition by sputtering technique.

[0045] Fig. 1 illustrates a nuclear fuel rod 2 intended for use in a light water reactor, in particular a pressurized water reactor (or PWR for "Pressurized Water Reactor") or a boiling water reactor (or BWR for "Boiling Water Reactor"), a "VVER" type reactor, an "RBMK" type reactor, or a heavy water reactor, for example of the "CANDU" type.

[0046] The nuclear fuel rod 2 has an elongated shape along a longitudinal axis A.

[0047] The nuclear fuel rod 2 comprises a cladding 4 containing nuclear fuel.

[0048] The sheath 4 is tubular and extends along the longitudinal axis A.

[0049] The sheath 4 is sealed airtight at each of its ends by a respective cap 6.

[0050] The nuclear fuel is, for example, in the form of a stack of pellets 8 arranged axially inside the cladding 4, each pellet 8 containing fissile material. The stack of pellets 8 is also called a "fissile column".

[0051] The nuclear fuel rod 2 comprises a spring 10 disposed inside the sheath 4, between the stack of pellets 8 and one of the plugs 6, to push the stack of pellets 8 towards the other plug 6. A void or plenum 12 is preferably present between the stack of pellets 8 and the plug 6 on which the spring 10 rests.

[0052] Fig. 2 represents a cross-sectional view of the sheath 4.

[0053] The sheath 4 comprises a substrate 14 provided with a protective coating 16.

[0054] The substrate 14 is tubular and extends along the longitudinal axis A. In other words, the substrate 14 is a straight tube whose central axis is the longitudinal axis A.

[0055] The substrate 14 has for example an external diameter between 8 mm and 15 mm, in particular between 9 mm and 13 mm, and / or a length between 1 m and 5 m, in particular between 2 m and 5 m.

[0056] The substrate 14 is made of pure zirconium or zirconium-based alloy.

[0057] The expression "pure zirconium" means a material containing at least 99% by weight of zirconium and the expression "zirconium-based alloy" means an alloy containing at least 95% by weight of zirconium.

[0058] The zirconium-based alloy is for example chosen from one of the known alloys such as M5, ZIRLO, El 10, HANA, N36, Zircaloy-2 and Zircaloy-4.

[0059] The substrate 14 has an internal surface 14A facing inwards and an external surface 14B facing outwards. The internal surface 14A defines the space for receiving the nuclear fuel. The external surface 14B is opposite the internal surface 14A.

[0060] The protective coating 16 covers the external surface 14B of the substrate 14.

[0061] The protective coating 16 has the function of protecting the external surface 14B from the substrate 14 of the external environment. In the absence of protective coating 16, the external surface 14B of the sheath 14 would be exposed to the external environment.

[0062] The protective coating 16 is made, for example, of a chromium-based material.

[0063] The term "chromium-based material" refers to a pure chromium material or a chromium-based alloy. A pure chromium material herein means a material comprising at least 99% chromium by weight. A chromium-based alloy herein means an alloy comprising at least 80% chromium by weight.

[0064] The thickness of the protective coating 16 is preferably between 5 pm and 30 pm, in particular between 10 pm and 20 pm.

[0065] A method for manufacturing the sheath 4 includes supplying the substrate 14 and depositing the protective coating 16 on the substrate 14 by physical vapor deposition by simultaneously implementing several different cathodic sputtering physical vapor deposition techniques.

[0066] Physical vapor-phase deposition by cathodic sputtering of a coating on A substrate is created by generating an electric field using a cathode (or "target") placed in a chamber containing a rarefied atmosphere, such as a neutral gas like argon. The electric field causes a plasma to form in the chamber, containing electrically charged atoms and particles (electrons, ions, etc.) which are precipitated onto the cathode by the electric field. This detachment dislodges atoms from the cathode (i.e., the cathode is sputtered, hence the term "sputtering"). These atoms, detached from the cathode, are then deposited onto the substrate. Optionally, a reactive gas, such as nitrogen or oxygen, is present in the rarefied atmosphere.

[0067] Advantageously, a physical vapor phase deposition by cathodic sputtering is achieved by magnetron cathodic sputtering.

[0068] Physical vapor deposition by magnetron sputtering of a coating on a substrate is carried out by generating an electric and magnetic field using a cathode (composed of a "target" and a "magnetron") arranged in a chamber containing a rarefied atmosphere formed for example of a neutral gas, such as argon, the electromagnetic field causing the appearance in the chamber of a plasma containing electrically charged atoms and particles (electrons, ions...) which are precipitated on the cathode under the effect of the electromagnetic field and detach atoms from the cathode (i.e. the cathode is sputtered, hence the expression sputtering), these atoms detached from the cathode then being deposited on the substrate.

[0069] The magnetron includes, for example, one or more permanent magnets and / or one or more electromagnets.

[0070] Predicting a magnetic field allows for better control of the trajectory of electrically charged particles reaching the cathode, which allows for better control of the coating deposition rate, in particular to obtain a higher coating deposition rate.

[0071] In the following, unless otherwise stipulated, the expressions "deposition technique" and "physical vapor phase deposition technique" refer to physical vapor phase deposition techniques by sputtering, possibly magnetron.

[0072] The manufacturing process of the sheath 4 thus includes the simultaneous implementation of several different physical vapor phase deposition techniques by cathodic sputtering to deposit the protective coating 16 on the substrate 14.

[0073] Physical vapor deposition techniques are implemented simultaneously using at least one cathode common to at least two of the simultaneously implemented physical vapor deposition techniques and / or at least one dedicated cathode, each dedicated cathode being used for the implementation of only one of the simultaneously implemented physical vapor deposition techniques. simultaneously.

[0074] Preferably, when several cathodes are used for the simultaneous implementation of different physical vapor deposition techniques, these cathodes are made of the same material.

[0075] In one embodiment, at least two of the different physical vapor deposition techniques are implemented simultaneously using a common cathode, by applying to this common electrode a combined excitation signal corresponding to the superposition of several elementary excitation signals, each elementary excitation signal corresponding to one of the physical vapor deposition techniques implemented simultaneously using said common electrode.

[0076] Each elementary excitation signal has, for example, a periodic pattern, the pattern being, for example, a plateau, a pulse or a train of pulses.

[0077] The combined excitation signal is obtained for example by emitting the elementary excitation signals simultaneously and in a synchronized manner such that the respective patterns of the elementary excitation signals are present sequentially in the combined excitation signal, the respective patterns of the elementary excitation signals being applied sequentially to the common cathode.

[0078] In the combined excitation signal, the pattern of each elementary excitation signal is present in time windows distinct from those of the pattern of each other elementary excitation signal forming the combined excitation signal. The pattern of each elementary excitation signal is present in time windows dedicated to that elementary excitation signal, to the exclusion of the patterns of the other elementary excitation signals.

[0079] Patterns of different elementary excitation signals are not present at the same instant in the combined excitation signal.

[0080] In one embodiment, a first physical vapor deposition technique and a second physical vapor deposition technique are implemented simultaneously using a common cathode by applying to this common cathode a combined excitation signal corresponding to the superposition of a first elementary excitation signal and a second elementary excitation signal, the first elementary excitation signal corresponding to the first physical vapor deposition technique and the second elementary excitation signal corresponding to the second physical vapor deposition technique, the first elementary excitation signal and the second elementary excitation signal being synchronized in such a way that their respective elementary patterns are alternated in the combined excitation signal.

[0081] As illustrated in [Fig. 3], a physical vapor deposition installation 20 by sputtering configured for the simultaneous implementation of several different physical vapor deposition techniques using a common cathode, and in particular for the simultaneous implementation of a first physical vapor deposition technique and a second physical vapor deposition technique are implemented simultaneously using a common cathode.

[0082] The installation 20 includes a chamber 22 for receiving one or more substrates 14, an atmosphere control device 24 for generating a rarefied atmosphere in the chamber 22, a common cathode 26 and an excitation device 28 connected to the common cathode 26.

[0083] The atmosphere control device 24 includes for example a pumping device 30 connected to the chamber 22 to generate a rarefied atmosphere in the chamber 22 and a gas supply device 32 fluidically connected to the chamber 22 to supply a neutral gas, e.g. argon and / or a reactive gas, e.g. nitrogen or oxygen.

[0084] The excitation device 28 is configured to generate a combined excitation signal applied to the common cathode 26 and corresponding to the superposition of elementary excitation signals for the implementation of physical vapor phase deposition technique.

[0085] Each physical vapor phase deposition technique is implemented by applying an elementary excitation signal to the associated cathode, the elementary excitation signal having a pattern repeated periodically, the pattern being for example a plateau, a pulse or a train of pulses.

[0086] The superposition of periodic excitation signals is carried out in a synchronized manner such that the respective patterns of the excitation signals are applied sequentially to the cathode.

[0087] The excitation device 28 is here configured for the simultaneous implementation of a first physical vapor deposition technique and a second physical vapor deposition technique using the common cathode 26.

[0088] The excitation device 28 comprises, for example, a first electrical generator 34 and a second electrical generator 36 connected in parallel to the common cathode 26, the first electrical generator 34 and the second electrical generator 36 being configured to generate respectively a first electrical signal for the implementation of the first physical vapor phase deposition technique and the second electrical signal for the implementation of the second physical vapor phase deposition technique, in a synchronized manner.

[0089] The installation 20 optionally includes a magnetic field generator 38 (or magnetron) configured to generate a magnetic field near the common cathode 26, for the implementation of vapor deposition techniques by pul cathodic verification called "magnetron" using the common cathode 26.

[0090] The magnetic field generator 38 comprises one or more permanent magnets and / or one or more electromagnets.

[0091] When the magnetic field generator 38 is active, the first physical vapor deposition technique and the second physical vapor deposition technique implemented simultaneously are magnetron sputtering physical vapor deposition techniques.

[0092] In operation, the atmosphere control device 24 generates a rarefied atmosphere in the chamber 22 and the excitation device 28 generates the combined excitation signal and applies it to the common cathode 26, so that the physical vapor phase deposition techniques are implemented simultaneously using the common cathode 26.

[0093] In particular, in the illustrated example, the first electric generator 34 and the second electric generator 36 generate the first elementary excitation signal and the second elementary excitation signal simultaneously, the first elementary excitation signal and the second elementary excitation signal being combined by superposition to generate the combined excitation signal.

[0094] If necessary, the magnetic field generator 38 generates a magnetic field in the vicinity of the common cathode 26.

[0095] Each of the physical vapor phase deposition techniques implemented simultaneously can be carried out in unipolar mode or in bipolar mode.

[0096] Subsequently, in the absence of further specification, each physical vapor phase deposition technique can be used in unipolar or bipolar mode.

[0097] The physical vapor phase deposition techniques implemented simultaneously are for example chosen from: high power pulsed magnetron sputtering (HiPIMS) unipolar or bipolar, unipolar or bipolar direct current (DC) magnetron sputtering, unipolar or bipolar pulsed direct current (pulsed-DC) magnetron sputtering, unipolar or bipolar medium frequency (MF) magnetron sputtering and unipolar or bipolar radio frequency (RF) magnetron sputtering.

[0098] In one embodiment, the common cathode 26 is used for the simultaneous implementation of a high-power pulsed magnetron sputtering (HiPIMS) unipolar or bipolar physical vapor deposition, and a medium-frequency (MF) magnetron sputtering physical vapor deposition.

[0099] Optionally, the installation 20 is configured to polarize the substrate 14 during the physical vapor deposition process. Polarizing the substrate 14 improves the deposition, particularly the quality and density of the coating. The substrate 14 is biased, for example, using a dedicated substrate 14 bias generator. The substrate 14 bias generator is configured, for example, to apply a constant voltage to the substrate, for example, a voltage on the order of 100V.

[0100] Fig. 4 comprises three graphs representing a first elementary excitation signal SI, a second elementary excitation signal S2 and a combined excitation signal SC resulting from the combination, and more particularly from the superposition of the first elementary excitation signal SI and the second elementary excitation signal S2, each graph indicating an instantaneous power of the corresponding excitation signal as a function of time.

[0101] The first elementary excitation signal SI is configured for the realization of a physical vapor phase deposition technique by high-power pulsed magnetron sputtering.

[0102] The first elementary excitation signal SI is periodic and based on a first pattern formed by a first pulse. The first elementary excitation signal SI thus comprises first repeated pulses with a first frequency Fl and a first power PL

[0103] The second elementary excitation signal S2 is configured for the realization of a medium-power magnetron sputtering vapor phase deposition technique.

[0104] The second elementary excitation signal S2 is periodic and based on a second pattern consisting of a train of identical second pulses with a second frequency F2 and a second power P2. The second elementary excitation signal S2 thus comprises a series of trains of second pulses, each train of second pulses comprising several successive identical pulses with a second frequency F2 and a second power P2.

[0105] A single train of second pulses is shown in [Fig.4]. The second elementary excitation signal S2 comprises several successive trains of second pulses.

[0106] Preferably, the first frequency Fl is strictly less than the second frequency F2 and / or the first power PI is strictly greater than the second power P2.

[0107] The duration of a train of second pulses of the second elementary excitation signal S2 preferably corresponds to the duration between a first pulse and the first subsequent pulse of the first elementary excitation signal SI, and the interval between a train of second pulses of the second elementary excitation signal S2 and the following train of second pulses preferably corresponds to the duration of a first pulse of the first elementary excitation signal SL

[0108] The first elementary excitation signal SI and the second elementary excitation signal S2 are synchronized in such a way that the first pattern and the second pattern are alternated in the combined excitation signal SC.

[0109] The superposition of the first elementary excitation signal SI and the second elementary excitation signal S2 results in a combined excitation signal SC comprising the first pulses at the first power PI and, between each first pulse and the first subsequent pulse, a train of second pulses at the second power P2.

[0110] In the combined SC excitation signal, the first motif and the second motif are formed sequentially, the sequence being repeated periodically.

[0111] The combined excitation signal SC allows the first physical vapor deposition technique and the second physical vapor deposition technique to be implemented simultaneously.

[0112] In particular, the first pulses at the first power PI and with the first frequency Fl enable the implementation of the first physical vapor deposition technique (high-power pulsed magnetron sputtering physical vapor deposition), the time intervals between the first pulses being exploited to implement the second physical vapor deposition technique (medium-frequency magnetron sputtering physical vapor deposition) which requires pulses at the second power P2 lower than the first power PI with a second frequency F2 higher than the first frequency FL

[0113] In one embodiment, the common cathode 26 is used for the simultaneous implementation of a high-power magnetron sputtering physical vapor deposition (HiPIMS) unipolar or bipolar and a unipolar or bipolar direct current (DC) magnetron sputtering physical vapor deposition.

[0114] [Fig.5] is analogous to [Fig.4] and differs from it in that the second elementary excitation signal S2 is intended for the realization of a physical vapor phase deposition technique by direct current magnetron sputtering.

[0115] The second elementary excitation signal S2 is periodic and based on a second pattern in the form of a second plateau at a second power P2. The second elementary excitation signal S2 thus comprises plateaus at a second power P2, the plateaus being separated by intervals at zero power, the plateaus preferably having a duration longer than that of the intervals.

[0116] The spacing between the intervals corresponds to the duration between the first pulses of the first elementary excitation signal SI and the duration of the intervals cor corresponding to the duration of the first pulses of the first elementary excitation signal SI.

[0117] Preferably, the first power PI is strictly greater than the second power P2.

[0118] The superposition of the first elementary excitation signal SI and the second elementary excitation signal S2 results in a combined excitation signal SC comprising the first pulses at the first power PI with a plateau at the second power P2 between each first pulse and the next first pulse.

[0119] In the combined SC excitation signal, the first motif and the second motif are formed sequentially, the sequence being repeated periodically.

[0120] The combined excitation signal SC allows the first physical vapor deposition technique and the second physical vapor deposition technique to be implemented simultaneously.

[0121] In particular, the first pulses at the first power PI and with the first frequency Fl enable the implementation of the first physical vapor deposition technique (high-power magnetron sputtering physical vapor deposition), the time intervals between the first pulses being exploited to implement the second physical vapor deposition technique (DC magnetron sputtering physical vapor deposition) which requires a DC current at the second power P2, lower than the first power PL

[0122] In one embodiment, at least one or each of the simultaneously implemented physical vapor deposition techniques is implemented using a dedicated cathode, by applying between this dedicated cathode and the substrate a specific excitation signal for the implementation of a single physical vapor deposition technique.

[0123] Each dedicated cathode is associated with a single physical vapor deposition technique and is distinct from each other cathode, dedicated or common.

[0124] In one embodiment, the excitation signal of each dedicated cathode is generated by a respective excitation signal generator.

[0125] An excitation device 28 in this case comprises a respective excitation signal generator associated with each dedicated cathode.

[0126] In one embodiment, a first physical vapor deposition technique is implemented using a first dedicated cathode, by applying to this first dedicated cathode a first excitation signal specific to the implementation of this first physical vapor deposition technique, and, simultaneously, a second physical vapor deposition technique is implemented using a second dedicated cathode, by applying to this second cathode dedicated a second specific excitation signal for the implementation of this first physical vapor phase deposition technique.

[0127] The installation 20 of [Fig.6] differs from that of [Fig.3], whose numerical references associated with the analogous elements are taken up again, in that the installation 20 includes a first dedicated cathode 26A for the implementation of a first physical vapor deposition technique by sputtering and a second dedicated cathode 26B, distinct from the first dedicated cathode 26A, for the implementation of a second physical vapor deposition technique different from the first physical vapor deposition technique.

[0128] Preferably, the first dedicated cathode 26A and the second dedicated cathode 26B are made of the same material.

[0129] The excitation device 28 is configured to simultaneously generate a first specific excitation signal applied to the first dedicated cathode 26A and a second specific excitation signal applied to the second dedicated cathode 26B.

[0130] As illustrated in [Fig.6], the excitation device 28 comprises for example a first electric generator 34 configured to generate the first specific excitation signal and connected to the first dedicated cathode 26A and a second electric generator 36 configured to generate the second specific excitation signal and connected to the second dedicated cathode 24B.

[0131] In operation, the atmosphere control device 24 generates a rarefied atmosphere in the chamber 22, the excitation device 28 simultaneously generates the first specific excitation signal applied to the first dedicated cathode 26A and the second specific excitation signal applied to the second dedicated cathode 26B, so as to simultaneously implement the first physical vapor deposition technique and the second physical vapor deposition technique.

[0132] In particular, the first electric generator 34 and the second electric generator 36 respectively generate the first specific excitation signal and the second specific excitation signal simultaneously, applied respectively to the first dedicated cathode 26A and the second dedicated cathode 26B, so as to implement simultaneously the first physical vapor deposition technique and the second physical vapor deposition technique.

[0133] Where appropriate, the magnetic field generator 38 generates a magnetic field in the vicinity of the first dedicated cathode 26A and / or in the vicinity of the second dedicated cathode 26B.

[0134] The physical vapor deposition techniques implemented simultaneously are, for example, chosen from: high-power pulsed magnetron sputtering (HiPIMS) unipolar or bipolar, direct current (DC) magnetron sputtering unipolar or bipolar, and magnetron sputtering at average frequency (MF) unipolar or bipolar.

[0135] In one embodiment, the first dedicated cathode 26A is used for the implementation of a high-power pulsed magnetron sputtering (HiPIMS) unipolar or bipolar and the second dedicated cathode 26B is used for the implementation of a medium-frequency (MF) magnetron sputtering.

[0136] In this case, the first specific excitation signal and the second specific excitation signal correspond respectively to the first elementary excitation signal SI and the second elementary excitation signal S2 of [Fig.3].

[0137] In one embodiment, the first dedicated cathode 26A is used for the implementation of a high-power pulsed magnetron sputtering (HiPIMS) unipolar or bipolar and the second dedicated cathode 26B is used for the implementation of a unipolar or bipolar direct current (DC) magnetron sputtering.

[0138] In this case, the first specific excitation signal corresponds to the first elementary SI excitation signal of [Fig.3] and the second specific excitation signal is a continuous constant signal to the second power P2.

[0139] Preferably, during physical vapor phase deposition, the substrate 14, which is tubular along its longitudinal axis A, is driven in rotation around its longitudinal axis A. This ensures a uniform deposition over the circumference of the substrate 14.

[0140] To do this, the installation 20 is configured to rotate the substrate 14 around its longitudinal axis A during the physical vapor phase deposition.

[0141] The invention is not limited to the embodiments and variant embodiments illustrated and described above.

[0142] It is possible to implement simultaneously exactly two vapor phase deposition techniques, using a common cathode or two dedicated cathodes, as illustrated in Figures 3 and 6.

[0143] More generally, the deposition of the protective coating 16 is carried out by simultaneously implementing one, two or more of two physical vapor phase deposition techniques by cathodic sputtering, using one or more common cathodes and / or one or more dedicated cathodes.

[0144] A physical vapor phase deposition installation 20 for carrying out the deposition of the protective coating 16 therefore comprises at least one common cathode 26 and / or at least one dedicated cathode 26A, 26B, the excitation device 28 being adapted to generate the combined excitation signal applied to each common cathode 26 and the specific excitation signal applied to each dedicated cathode 26A, 26B.

[0145] Each common cathode is used to implement a group of techniques physical vapor deposition comprising at least two physical vapor deposition techniques.

[0146] Each group of physical vapor deposition techniques includes, for example, two physical vapor deposition techniques (this is a pair or couple of physical vapor deposition techniques) or more than two physical vapor deposition techniques.

[0147] Each group of physical vapor deposition techniques is different from the possible other group(s) of physical vapor deposition techniques, while possibly containing at least one physical vapor deposition technique common to one or more of the other groups of physical vapor deposition techniques when several groups of physical vapor deposition techniques are implemented simultaneously, each using a respective common cathode.

[0148] Each dedicated cathode is associated with a respective physical vapor deposition technique, while possibly corresponding to a physical vapor deposition technique from one or more groups of physical vapor deposition techniques when at least one group of physical vapor deposition techniques is implemented simultaneously with the physical vapor deposition technique associated with the dedicated cathode.

[0149] In one embodiment, the deposition of the protective coating 16 is carried out by simultaneously implementing a first physical vapor deposition technique, a second physical vapor deposition technique and a third physical vapor deposition technique, the first physical vapor deposition technique and the second physical vapor deposition technique being implemented using a common cathode, the third technique being implemented using a dedicated cathode separate from the common cathode.

[0150] In one embodiment, the deposition of the protective coating 16 is carried out by simultaneously implementing a first physical vapor deposition technique, a second physical vapor deposition technique and a third physical vapor deposition technique, the first physical vapor deposition technique and the second physical vapor deposition technique being implemented using a first common cathode, the first physical vapor deposition technique and the third physical vapor deposition technique being implemented using a second common cathode distinct from the first common cathode.

[0151] In one embodiment, the deposition of the protective coating 16 is carried out by simultaneously implementing a first physical vapor deposition technique, a second physical vapor deposition technique and a third different physical vapor phase deposition techniques, implemented respectively using a first dedicated cathode, a second dedicated cathode and a third dedicated cathode.

[0152] In one embodiment, the deposition of the protective coating 16 is carried out by simultaneously implementing a first physical vapor deposition technique and a second physical vapor deposition technique, the first physical vapor deposition technique and the second physical vapor deposition technique being implemented using a common cathode, the first physical vapor deposition technique being implemented using a first dedicated cathode separate from the common cathode, and, optionally, the second vapor deposition technique being implemented using a second dedicated cathode, separate from the common cathode and the first dedicated cathode.

[0153] In the examples indicated above, the first physical vapor deposition technique, the second physical vapor deposition technique and the third physical vapor deposition technique implemented simultaneously are, for example, chosen from high-power pulsed magnetron sputtering (HiPIMS) unipolar or bipolar, unipolar or bipolar direct current (DC) magnetron sputtering and unipolar or bipolar medium frequency (MF) magnetron sputtering.

[0154] The examples indicated above can be combined for the simultaneous implementation of the first physical vapor deposition technique, the second physical vapor deposition technique and the third physical vapor deposition technique implemented simultaneously.

[0155] Each of the first physical vapor deposition technique, the second physical vapor deposition technique and the third physical vapor deposition technique can be implemented simultaneously using at least one common cathode and one dedicated cathode.

[0156] Furthermore, the invention can be applied to substrates other than nuclear fuel rod cladding substrates.

[0157] When the substrate is symmetrical about a longitudinal axis, preferably, the physical vapor phase deposition is carried out by rotating the substrate around its longitudinal axis to ensure uniform deposition over the circumference of the substrate.

[0158] Thanks to the invention, it is possible to carry out the deposition of a protective coating in a rapid manner, and better suited with the production of nuclear fuel rod cladding on an industrial scale.

[0159] The deposition rate of the protective coating using a deposition technique High-power pulsed magnetron sputtering (HiPIMS) physical vapor phase deposition technique and, simultaneously, another physical vapor phase deposition technique such as direct current (DC) magnetron sputtering or medium frequency (MF) magnetron sputtering, can be two to four times faster than the deposition rate using only the high-power pulsed magnetron sputtering (HiPIMS) physical vapor phase deposition technique, while maintaining the same deposition quality.

[0160] In particular, the use of at least one common cathode 26 makes it possible to maximize the time of use of the common cathode 26.

[0161] In particular, a common cathode 26 used for the implementation of a high-power pulsed magnetron sputtering physical vapor deposition technique (HiPIMS) and, simultaneously, another sputtering physical vapor deposition technique such as direct current (DC) magnetron sputtering or medium frequency (MF) magnetron sputtering, can be used with a higher utilization rate than if it were used only for the implementation of the high-power pulsed magnetron sputtering physical vapor deposition technique (HiPIMS).

[0162] The time intervals between the high-power pulses of the high-power pulsed magnetron sputtering physical vapor deposition technique (HiPIMS) are in fact used for the implementation of said other sputtering physical vapor deposition technique.

[0163] The combination of several physical vapor deposition techniques by cathodic sputtering makes it possible to benefit from the advantages of the different techniques, in particular in terms of roughness of the protective coating 16, corrosion resistance of the protective coating 16, density of the protective coating 16 and / or adhesion of the protective coating 16 to the substrate 14.

[0164] Preferably, the deposition of the protective coating 16 is carried out in such a way that the sheath 4 has one or more of the following characteristics:

[0165] - the roughness of the protective coating is equal to or less than 2 pm, in particular equal to or less than 1 pm;

[0166] - the corrosion resistance of the protective coating 16 made of material to chromium base is such that the chromium oxide layer Cr2O3 is less than 1 pm after five years of use in the core of a nuclear reactor during normal (non-accidental) operation; and / or

[0167] - the density of the protective coating is greater than 98%.

[0168] Density here refers to the percentage of the theoretical density of the same material compact, or equivalently, as the theoretical density minus the porosity rate. A density greater than 98% corresponds to a porosity rate less than 2%.

[0169] The quality of the adhesion between the substrate 14 and the protective coating 16 is tested for example by implementing an expansion due to compression test known by the acronym EDC for "Expansion Due to Compression" in English.

[0170] Combining several sputtering physical vapor deposition techniques makes it possible to reduce the overall size of a physical vapor deposition plant, due to the reduction in the number of cathodes required to achieve a desired productivity.

[0171] The table below presents the results of three examples provided as non-limiting examples and one comparative example. Parameter Example 1 1 cathode 2 superimposed signals HiPIMS+DC Example 2 1 cathode, 2 superimposed signals HiPIMS+MF Example 3 2 cathodes 1 signal / cathode HiPIMS+DC Example 4 1 cathode 1 HiPIMS signal Chamber pressure (Pa) 0.2 0.15 0.2 0.2 Target-to-substrate distance (mm) 100 100 120 80 Deposition rate (pm / h) 6 5.5 7 2 HiPIMS peak power density (W / cm2) 85 80 70 70 HiPIMS duty cycle (%) 4 4 6 9 DC power density (W / cm2) 1 - 0.8 - DC duty cycle (%) 78 - 100 - MF power density (W / cm2) - 1.2 - - Im- frequency - 20 - - current pulses (kHz)

[0172] [Table 1]

[0173] In the first example (Example 1), a single cathode is used to simultaneously implement high-power pulsed magnetron sputtering physical vapor deposition (HiPIMS) and direct current (DC) magnetron sputtering physical vapor deposition, by applying two superimposed signals to the cathode.

[0174] In the second example (Example 2), a single cathode is used to simultaneously implement high-power pulsed magnetron sputtering physical vapor deposition (HiPIMS) and medium-frequency (MF) magnetron sputtering physical vapor deposition, by applying two superimposed signals to the cathode.

[0175] In the third example (Example 3), two cathodes are used simultaneously, one to simultaneously implement high-power pulsed magnetron sputtering (HiPIMS) physical vapor deposition; and the other to implement direct current (DC) magnetron sputtering physical vapor deposition. Each cathode receives an excitation signal corresponding to the relevant physical vapor deposition technique.

[0176] In the fourth example (Example 4), which is a comparative example, a single cathode is used to implement a single physical vapor deposition technique, more specifically a high-power pulsed magnetron sputtering (HiPIMS).

[0177] The deposition rates obtained in the first, second and third examples are respectively 6 pm / h, 5.5 pm / h and 7 pm / h, whereas the deposition rate achieved by implementing a single physical vapor phase deposition technique by sputtering would be on the order of 2 to 3 pm / h, as illustrated in the fourth example in which the deposition rate is 2 pm / h.

Claims

Demands

1. Method of manufacturing a nuclear fuel rod cladding (4) comprising a substrate (14) covered with a protective coating (16), the manufacturing method comprising - supplying the substrate (14); and - deposition of the protective coating (16) on the substrate (14) by physical vapor deposition by sputtering, by simultaneously implementing several different physical vapor deposition techniques by sputtering.

2. A manufacturing method according to claim 1, wherein at least two of the different physical vapor deposition techniques by sputtering are carried out simultaneously using a common cathode (26).

3. A manufacturing method according to claim 2, comprising applying to each common cathode (26) a combined excitation signal (SC) corresponding to the superposition of at least two elementary excitation signals (SI, S2), each elementary excitation signal (SI, S2) being formed of a periodic pattern corresponding to a respective sputtering physical vapor deposition technique among the sputtering physical vapor deposition techniques implemented simultaneously using said common cathode (26), the elementary excitation signals (SI, S2) being synchronized such that their respective patterns are present sequentially in the combined excitation signal (SC).

4. A manufacturing method according to claim 3, wherein each elementary excitation signal (SI, S2) is generated by a respective excitation signal generator, the elementary excitation signals (SI, S2) being synchronized and superimposed to form the combined excitation signal (SC) applied to said common cathode (26).

5. A manufacturing method according to any one of the preceding claims, wherein at least one of the simultaneously implemented physical vapor deposition techniques by sputtering is implemented using a dedicated cathode (26A, 26B), by applying to this dedicated cathode (26A, 26B) an excitation signal for the implementation of this physical vapor phase deposition technique.

6. A manufacturing method according to claim 1, wherein each of the simultaneously implemented physical vapor deposition techniques by sputtering is implemented using a dedicated cathode (26A, 26B), by applying to this dedicated cathode (26A, 26B) an excitation signal for the implementation of this physical vapor deposition technique.

7. A manufacturing method according to claim 5 or 6, wherein the excitation signal of each dedicated cathode (26A, 26B) is generated by a respective excitation signal generator (26A, 26B).

8. A manufacturing method according to any one of the preceding claims, wherein the physical vapor deposition techniques implemented simultaneously are selected from: high-power pulsed magnetron sputtering (HiPIMS) unipolar or bipolar, unipolar or bipolar direct current (DC) magnetron sputtering, unipolar or bipolar pulsed-DC magnetron sputtering, unipolar or bipolar medium frequency (MF) magnetron sputtering, and unipolar or bipolar radio frequency (RF) magnetron sputtering.

9. A manufacturing method according to any one of the preceding claims, wherein the substrate (14) is made of a zirconium-based material and / or the protective coating (16) is made of a chromium-based material.

10. A manufacturing method according to any one of the preceding claims, wherein the thickness of the protective coating after the deposition step is between 5 pm and 30 pm, in particular between 10 pm and 20 pm.

11. A manufacturing method according to any one of the preceding claims, wherein the substrate has a shape of revolution about a central axis, the manufacturing method comprising rotating the substrate (14) about the central axis during the deposition step.

12. A manufacturing method according to any one of the preceding claims, comprising polarizing the substrate (14) during coating deposition.

13. Nuclear fuel rod cladding comprising a substrate (14) covered with a protective coating (16) deposited on the substrate by physical vapor deposition by simultaneously implementing a plurality of different physical vapor deposition techniques by sputtering.

14. Physical vapor deposition installation, comprising a chamber (22), at least one atmosphere control device (24) for generating a rarefied atmosphere in the chamber (22), at least one cathode (26, 26A, 26B) and an excitation device (28), the installation being configured for the deposition of a protective coating (16) onto a substrate (14) introduced into the chamber (22) by simultaneously implementing several different sputtering physical vapor deposition techniques using the cathode(s) (26, 26A, 26B).

15. Installation according to claim 14, comprising at least one common cathode (26) for the simultaneous implementation of at least two of the simultaneously implemented sputtering physical vapor deposition techniques, the excitation device (28) being configured to generate a combined excitation signal (SC) of the common cathode (26) which corresponds to the superposition of several elementary excitation signals (SI, S2), each elementary excitation signal (SI, S2) having a periodic pattern corresponding to a respective of the sputtering physical vapor deposition techniques implemented simultaneously using said common cathode (26), the elementary excitation signals (SI, S2) being combined in such a way that their respective patterns are present sequentially in the combined excitation signal (SC).

16. Installation according to claim 14 or 15, comprising at least one dedicated cathode (26A, 26B) for the implementation of one of the sputtering physical vapor deposition techniques implemented simultaneously, the excitation device being configured to generate a respective excitation signal for each dedicated cathode (26A, 26B), the excitation signal corresponding to the sputtering physical vapor deposition technique associated with that dedicated cathode.

17. Installation according to any one of claims 14 to 16, configured for polarization of the substrate (14) during coating deposition.

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