Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
  • G21C3/02—Fuel elements
  • G21C3/04—Constructional details
  • G21C3/16—Details of the construction within the casing
  • G21C3/18—Internal spacers or other non-active material within the casing, e.g. compensating for expansion of fuel rods or for compensating excess reactivity
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/02—Pretreatment of the material to be coated
  • C23C16/0209—Pretreatment of the material to be coated by heating
  • C23C16/0218—Pretreatment of the material to be coated by heating in a reactive atmosphere
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
  • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
  • C23C16/38—Borides
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/448—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for generating reactive gas streams, e.g. by evaporation or sublimation of precursor materials
  • C23C16/452—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for generating reactive gas streams, e.g. by evaporation or sublimation of precursor materials by activating reactive gas streams before their introduction into the reaction chamber, e.g. by ionisation or addition of reactive species
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E30/00—Energy generation of nuclear origin
  • Y02E30/30—Nuclear fission reactors

Definitions

• the invention relates to a method of coating a substrate of passivable metal or of an alloy based on passivable metal, such as zirconium, with a layer of metallic boride.
• the invention applies to the coating of zirconium alloy tubes with a layer of a boride such as ZrB 2 used as a neutron poison consumable in the core of a nuclear reactor.
• a boron compound such as boride ZrB 2
• the regular disappearance of boron under the effect of neutrons does not generate absorbent isotopes, unlike the case of gadolinium and l 'erbium.
• the use of ZrB 2 zirconium diboride in the form of a coating and in particular an internal coating of the cladding tubes makes it possible to avoid using an under-enriched fissile material to fill the sheaths of the pencils coated with consumable poison and to limit the amount of fissile material, for example U0 2 , contained in pencils coated with consumable poison.
• the use of coatings of ZrB 2 therefore makes it possible to use assemblies of consumable poison fuel containing the same quantity of fissile material as the other assemblies of the nuclear reactor core.
• the use of ZrB 2 can allow a more homogeneous distribution of the consumable poison in the core of the nuclear reactor, each of the assemblies containing consumable poison comprising a large number of pencils in each of which a small amount of ZrB 2 is deposited. This gives a very satisfactory adjustment of the power distribution in the fuel assembly comprising the consumable poison and in particular under more satisfactory conditions than in the case of the use of gadolinium.
• tubes made of a composite material containing boron inside a metal matrix are inserted into the cladding tubes and then cold drawn with the cladding tubes to ensure mechanical connection of the cladding tube and the composite coating tube.
• This process which must be carried out tube by tube, is delicate and costly to implement.
• it is very difficult to avoid the presence of boron in the end parts of the tube on which the plugs for closing the fuel rod must be welded subsequently.
• US-A-4,695,476 and 4,762,675 propose to react a deposit of boron or ZrB 2 inside cladding tubes by thermal decomposition of borane or organometallic compounds, in the presence of hydrogen to limit the formation of free carbon.
• the products used in the implementation of this process are toxic and on the other hand their stability is poor, so that it is difficult to control the characteristics of the deposit all along the tube.
• the deposit of boron or boron compound is hard and brittle, which risks compromising the behavior of the sheath due to the initiation of scratches during the introduction of the fuel pellets inside. sheath.
• FR-A-94-14466 discloses a process for producing Zr0 2 oxide layers on the surface of a zirconium or zirconium alloy substrate which consists in pre-oxidizing the substrate by an oxidizing gas excited in a cold plasma and then carrying out the deposition of metal oxide on the pre-oxidized substrate by a chemical gas deposition process using a metal halide in gaseous form which is oxidized by an excited reactive gas mixture in cold plasma.
• a chemical gas deposition process using a metal halide in gaseous form which is oxidized by an excited reactive gas mixture in cold plasma.
• Such a method makes it possible to deposit at a moderate temperature, which in particular makes it possible to avoid damaging the structure of the substrate.
• such a process is not intended for the deposition of absorbent substances on a substrate such as a cladding tube of a fuel assembly.
• the object of the invention is therefore to propose a method of coating a metal substrate with a passivable metal or an alloy based on a passivable metal such as zirconium, with a layer of metal boride. lique, this process should allow obtaining a homogeneous coating layer having very good characteristics, simply and with a limited production cost.
• a passivable metal or an alloy based on a passivable metal such as zirconium
• a surface preoxidation of the substrate is carried out by bringing it into contact with an oxidizing gas excited in a cold plasma, the substrate being placed in the plasma post-discharge flow and brought to a temperature below 500 "C, and
• a metal boride is deposited at a temperature below 500 ⁇ C on the pre-oxidized substrate, by bringing them into contact with each other and with the substrate placed in the post-discharge in plasma flow, a metal halide, a compound boron and a reducing element, in the form of gaseous substances, at least one of the gaseous substances being excited in a cold plasma.
• Figure 1 is a schematic view of the entire coating device.
• FIGS. 2A and 2B schematically represent two alternative embodiments of part of the installation in which the cold plasma is generated.
• FIG. 1 an installation for implementing the process according to the invention in the case of the coating of a cladding tube made of a zirconium alloy such as Zircaloy 4 with a ZrB zirconium boride layer 2 .
• the installation shown in FIG. 1 comprises three main parts, namely a deposition reactor 1, a metalli ⁇ cal halide synthesis reactor 2 and a gas supply assembly 3.
• the deposition reactor 1 comprises a tube reactor
• an internal tube 8 intended to ensure the separation of the gaseous substances introduced into the reactor tube up to the vicinity of one end of the cladding tube 5 to be coated. Heating and maintaining the temperature at
• the interior of the reactor tube 4, of the cladding tube 5 constituting the substrate, are provided by an electric furnace 9 in the region of the tube containing the substrate 5.
• the metal halide synthesis reactor 2 comprises an enclosure 13 which opens at one of its ends into an annular space between the envelope of the reactor tube 4 and the internal tube 8, in an area close to the inlet part. of the reactor tube 4.
• the casing 13 of the synthesis reactor contains metal to be chlorinated 14 in a divided form, for example in the form of chips or sponge. In the embodiment which will be described below, the metal to be chlorinated is zirconium.
• the zirconium in divided form is supported by a layer of porous material 15 which can be constituted by quartz wool for example. This avoids the transfer of small metal chips in the reactor tube 4 while allowing the evacuation of gaseous zirconium compounds in the reactor tube 4.
• the casing 13 of the synthesis reactor and the inlet part of the reactor tube 4 in which leads to the outlet of the synthesis reactor are surrounded by a heating strip 16 making it possible to heat and maintain the temperature in the enclosure of the synthesis reactor containing the zirconium 14 in divided form. ó ⁇ ment, the enclosure of the synthesis reactor is maintained at a temperature of about 300 C to C which is réali ⁇ Sée the synthesis of a metal halide from the zirconium 14.
• a thermocouple 17 measures the tempera ⁇ ture in the casing 13 of the synthesis reactor, around the mass of zirconium 14 in divided form.
• the gas supply device 3 comprises four gas distribution units 18, 19, 20 and 21.
• the gas distribution units 18, 19, 20 and 21 each comprise at least two different gas distribution lines arranged in parallel .
• the distribution unit 19 comprises a first line 19a for distributing an inert drive gas such as argon for example, and a line 19b for distributing oxygen.
• the unit 19 may also include distribution lines for other gases and in particular for distribution of hydrogen and nitrogen.
• the lines such as 19a and 19b of the unit 19 include a regulator 22 at the inlet end of the line connected to the gas source. Sources of gases such as argon and oxygen consist of bottles or tubes on the outlet of which the regulator can be fixed.
• a mass flow regulator such as 23 and a stop valve such as 24 are arranged in this order on the lines such as 19a and 19b which are interconnected at a branch, the outlet of which is connected via a stop valve 25 and a second stop valve 26 to an associated discharge tube 27 to an excitation structure 28 making it possible to transfer the energy supplied by a microwave generator to the plasma gases supplied by the distribution unit 19 and arriving in the discharge tube 27.
• the microwave generator operates at the legal microwave frequency of 2450 MHz and delivers a continuously adjustable output power from 0 to 200 W.
• Other microwave frequencies (433, 915 MHz, ... ) as well as other types of plasma sources such as radio frequency generators can also be used.
• the energy of the microwave generator is transported by electromagnetic waves guided by a rigid brass waveguide.
• the transfer of energy between the incident wave and the plasma gases is ensured by a device called surfaguide mounted on the waveguide and coupled to impedance matching devices allowing both to attenuate the reflected power.
• the cold plasma created by passage of the plasma gases in the excitation structure 28 is introduced into the internal tube 8 of the reactor tube 4; the outlet of the discharge tube 27 is connected to the inlet part of the reactor tube 4, in its central part, inside the internal tube 8.
• the distribution unit 18 comprises two lines 18a and 18b making it possible to distribute an inert gas such as argon and hydrogen constituting the reducing reactive gas, respectively.
• Each of the lines 18a and 18b has a deten ⁇ 29 connected to the outlet of the gas source supplying the line and a mass flow regulator 30.
• the two lines 18a and 18b are connected, via a branch and a stop valve 31, to a pipe 32 for introducing inert gas and reducing gas into the peripheral space between the inlet part of the reactor tube 4 and the internal tube 8.
• the distribution unit 21 comprises two lines 21a and 21b ensuring the distribution, respectively, of an inert entraining gas, generally consisting of argon and of a boron compound in gaseous form which can be for example a halide such as chloride BC1 3 or another boron compound constituting a precursor of the layer of boride to be deposited in the reactor tube, such as B 2 H 6 for example.
• an inert entraining gas generally consisting of argon and of a boron compound in gaseous form which can be for example a halide such as chloride BC1 3 or another boron compound constituting a precursor of the layer of boride to be deposited in the reactor tube, such as B 2 H 6 for example.
• the distribution lines 21a and 21b are connected via a branch and a stop valve 33, to a pipe 34 connected at its end opposite to the distribution unit 21, at the inlet of the discharge tube 27, between the stop valves 25 and 26, by means of a stop valve 35.
• Each of the distribution lines 21a and 21b comprises a regulator 36 placed at the outlet of a gas source (for example a container containing argon or chloride BC1 3 ) and a mass flow regulator 37.
• a gas source for example a container containing argon or chloride BC1 3
• a mass flow regulator 37 for example a container containing argon or chloride BC1 3
• Driving argon and a gaseous boron compound such as BC1 3 can be sent into the discharge tube 27 optionally in admixture with plasma gases supplied by the distribution unit 19.
• the mixture of argon and boron trichloride BC1 3 can be introduced. duit at the inlet of the discharge tube 27, upstream of the excitation structure 28 or, on the contrary, as it is visible in FIG. 2B, downstream of the excitation structure 28, the plasma gases such that argon and hydrogen being introduced into the discharge tube upstream of the excitation structure 28.
• a pressure gauge 38 makes it possible to measure the pressure of the gases at the inlet of the discharge tube 27, upstream of the excitation structure 28.
• the gas distribution unit 20 comprises two distribution lines 20a and 20b ensuring respectively the distribution an inert diluent gas such as argon and a halogen gas such as chlorine.
• Each of the distribution lines 20a and 20b comprises a pressure regulator 39 fixed on the outlet of the gas source which can be constituted by a bottle or a tube and a mass flow regulator 40.
• the two lines 20a and 20b are connected, by l through a branch and a stop valve 41, to a pipe 42 opening out inside the casing 13 of the chlorination reactor 2, on which a stop valve 43 is arranged.
• a gas confinement device concentrates the reagents hitherto separated by the internal tube 8, inside the cladding tube.
• the valve 11 makes it possible to adjust the working pressure, that is to say the pressure of the gases in circulation in contact with the surface of the substrate to be coated.
• the process according to the invention is carried out in two phases, a first phase being a phase of pre-oxidation of the substrate at a temperature below 500 ° C and preferably at a temperature below 480 ⁇ C.
• l distribution unit 19 which allows a mixture of argon and oxygen to be sent into the discharge tube 27.
• the mixture of argon-oxygen gas is excited by the excitation structure 28 connected to the microwave generator, so that the surface preoxidation of the cladding tube 5 is carried out using the oxidizing gas constituted by the argon-oxygen mixture excited in a cold plasma.
• the substrate heated to a temperature below 500 "C and generally below 480 ⁇ C is placed in the plasma post-discharge.
• the zirconium oxide or zirconia layer formed in the preoxidation phase is perfectly adherent and compact and covers the substrate so as to protect it effectively from hydriding during the second phase of the process during which a coating consisting of zirconium boride ZrB 2 is deposited on the pre-oxidized substrate.
• Zirconium boride is in fact produced by reduction by hydrogen of a boron halide (BC1 3 ) and a zirconium halide (ZrCl 4 ) mixed in the vicinity of the zirconium substrate.
• the second phase of the treatment which consists of a vapor phase deposition of the zirconium boride ZrB 2 on the pre-oxidized substrate can be carried out immediately after the pre-oxidation phase, insofar as the coating is deposited at a temperature greater than or equal to that of the pre-oxidation phase.
• the chemical vapor deposition treatment is carried out at a temperature slightly higher than the preoxidation temperature, the rise in temperature of the furnace is achieved with a sweeping of the interior of the reactor tube by a flow argon, to avoid excessive oxidation of the cladding tube and to evacuate the oxygen which is still present in the reactor tube. Oxygen is indeed undesirable during the synthesis of borides by reduction of halides.
• the reactive gases are introduced into the reactor tube.
• the distribution unit 20 makes it possible to send into the envelope 13 of the halide synthesis reactor 2, a mixture of argon and chlorine which comes into contact with the zirconium in divided form 14 which has previously been brought to a reaction temperature of the order of 300 ⁇ C by heating using the heating strip 16, this reaction temperature being controlled by the thermocouple 17.
• the contact of the chlorine entrained by argon with the zirconium produces zirconium tetrachloride.
• the conditions for admitting chlorine and temperature into the synthesis reactor 2 are adjusted so producing a desired flow rate of chloride ZrCl 4 which enters the reactor tube, through the porous material 15.
• the flow rate of zirconium tetrachloride is fixed by the flow rate of chlorine according to the needs of the reaction inside the reactor tube 4.
• Argon and hydrogen are introduced into the annular space between the inner tube 8 and the inlet part of the reactor tube so that these gases mix with the gaseous zirconium chloride flowing in the reactor tube 4 and entrain the gas mixture towards the substrate 5 brought to the reaction temperature.
• the plasma gas distribution unit 19 can be used to send argon or a mixture of argon and hydrogen to the inlet portion of the discharge tube 27.
• the distribution unit 21 can be used sée to send a mixture of argon and boron compound such as boron trichloride BC1 3 , in the discharge line 27, either upstream or downstream of the excitation structure 28. It is therefore possible to put implementing the second phase of the process for carrying out the chemical vapor deposition of zirconium boride on the cladding tube 5, in different ways depending on the nature of the gases subjected to excitation by microwaves and therefore according to the nature of the gas constituting the post-discharge.
• This excitation mode corresponds to the configuration of the installation shown in FIG. 1 or to the realization of the excitation as represented in FIG. 2A.
• a mixture of argon, hydrogen and BC1 3 is brought to the inlet of the discharge tube 27.
• the mixture of gas activated in the discharge tube is sent into the internal tube 8 inside the reactor tube 4 so that the reactive gases BC1 3 , hydrogen and ZrCl 4 are only mixed at the exit of the internal tube 8 in contact with the surface of the cladding tube 5 constituting the substrate brought to the reaction temperature.
• This embodiment corresponds to that of FIG. 2B in which a mixture of argon and hydrogen is introduced at the inlet of the discharge tube 27 and a mixture of argon and BC1 3 in the excited argon-hydrogen gas stream, downstream of the excitation structure 28.
• This method of introducing BC1 3 into the argon-hydrogen post-discharge makes it possible to avoid deposition of boron on the walls of the discharge tube 27.
• This mode of gas distribution with a hydrogen / BCl 3 ratio close to 1 made it possible to produce films of zirconium diboride ZrB 2 having very fine crystals and a growth kinetics of 0.5 ⁇ m / h on the upstream end of the substrate 5.
• This embodiment corresponds to the embodiment shown in FIG. 2B with introduction of argon at the inlet of the discharge tube 27 and introduction of BC1 3 into the argon discharge downstream of the excitation structure 28.
• This mode of distribution of the plasma gas genes makes it possible to reduce the reactivity of boron trichloride BC1 3 , so that no deposition of boron occurs in the discharge tube.
• the limited excitation of the precursor BC1 3 makes it possible to obtain a coating of zirconium diboride ZrB 2 .
• the growth speed of the coating is of the order of one micrometer per hour at the upstream end of the substrate, this speed being decreasing along the length of the substrate.
• the chlorinator is located upstream of the gas excitation.
• the tests carried out show that the activation of ZrCl 4 leads, in the presence of hydrogen (and even in the absence of hydrogen), to the formation of lower chloru ⁇ res such as ZrCl 3 or ZrCl 2 , which are not volatile at temperatures of work.
• the formation of these chlorides further reduces the content of volatile species capable of transporting the zirconium element and of developing a coating of zirconium boride on the substrate. By the way, the grains of powder formed can become encrusted in the deposit during formation and thus create defects.
• the chlorinator is located immediately downstream of the discharge plasma.
• the excitation of ZrCl 4 is much less strong than in the previous case and it does tend to increase the reactivity of ZrCl 4 .
• the growth rates observed in cases a to d are increased and can reach 10 ⁇ m / h .
• the reduction to lower chlorides contributes, as in the case e, to reducing the number of volatile carriers of the zirconium element and the deposition rate is low.
• the process according to the invention therefore made it possible to obtain coatings of zirconium boride ZrB 2 which were perfectly adherent to a substrate made of zirconium alloy.
• the coatings can be obtained either on the outer surface of a zirconium alloy cladding tube, or on the inner surface of the tube depending on the pumping and circulation mode of the reactive gases used.
• the temperature of the substrate and of the gaseous compounds during the two phases of the coating operation is limited to a level always below 500 ⁇ C, generally below 480 ° C, and in some cases below 250 "C.
• the coating obtained is perfectly adherent to the surface of the substrate and it is possible to adjust the conditions for implementing the process to obtain a constant thickness over the entire length of the substrate.
• the consumption of the reagents inside the reactor tube during their circulation along the substrate can produce a decrease in the partial pressure of these reactants during the circulation of the gas flow along the substrate.
• the thickness of the coating layer is likely to decrease in the direction of circulation of the gaseous reactants.
• This effect can be compensated for by an increase in the reactivity of the gaseous compounds in the form of halide, by imposing for example example a temperature gradient to compensate for the effect of the decreasing concentration gradient in the circulation of gases.
• an oven can be used having several regulation zones distributed along the axial length of the reactor tube.
• Limiting the temperature of the substrate during coating makes it possible to avoid modifying the struc- ture of the substrate obtained after forming and heat treatment.
• the homogeneity of the coating over the entire length of the substrate can also be increased by increasing the flow rate of carrier gas.
• the yield will be reduced in every point so that the concentration of reactive species will remain sufficient at the end of the tube for the deposition kinetics to remain equivalent. to what it is tube start.
• the reactor tube may have characteristics different from those which have been described, depending on the nature, shape and dimensions of the substrate.
• the reactor tube can be placed both with its vertical axis and with its horizontal axis, in the case where the substrate is a cladding tube.
• the mixing of the gaseous reactants can be done by means of a gas containment device.
• the invention can be applied to the coating of substrates constituted by a passivable metal or alloy other than zirconium or a zirconium alloy.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Metallurgy (AREA)
• Mechanical Engineering (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Physics & Mathematics (AREA)
• General Engineering & Computer Science (AREA)
• Inorganic Chemistry (AREA)
• High Energy & Nuclear Physics (AREA)
• Plasma & Fusion (AREA)
• Chemical Vapour Deposition (AREA)

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• 1995
  • 1995-12-27 FR FR9515582A patent/FR2743088B1/fr not_active Expired - Fee Related
• 1996
  • 1996-11-28 EP EP96941074A patent/EP0870074A1/de not_active Withdrawn
  • 1996-11-28 WO PCT/FR1996/001889 patent/WO1997024470A1/fr not_active Ceased
  • 1996-12-19 ZA ZA9610686A patent/ZA9610686B/xx unknown

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