Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B21/00—Nitrogen; Compounds thereof
  • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
  • C01B21/0615—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with transition metals other than titanium, zirconium or hafnium
  • C01B21/063—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with transition metals other than titanium, zirconium or hafnium with one or more actinides, e.g. UN, PuN
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/90—Carbides
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/06—Metal silicides
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
• • 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
  • G21C3/42—Selection of substances for use as reactor fuel
  • G21C3/58—Solid reactor fuel Pellets made of fissile material
  • G21C3/62—Ceramic fuel
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/30—Particle morphology extending in three dimensions
  • C01P2004/32—Spheres
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/80—Compositional purity
• • 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
  • Y02E30/10—Nuclear fusion reactors
• • 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

• This invention relates to processes for the preparation of powders and in particular, powders of refractory metal compounds, such as uranium carbide, uranium nitride and uranium silicide.
• the object of the invention is to make such processes more economical than at present, particularly by dispensing with the grinding step generally necessitated in conventional methods.
• a process for the preparation of a refractory metal compound in powder form comprises forming a metal-ceramic composition of the compound and of a metal, as hereinafter defined, treating the composition with at least one agent which acts upon the metal to cause disintegration of the composition and separating the desired compound in powder form.
• the metal-ceramic composition is preferably formed by sintering the compound and the metal together.
• metal as used in relation to the material associated with the refractory metal compound in the composition means a metal per se or such metal in alloyed form. It is preferably for the metal to be the same as that in the refractory compound.
• the agent causes disintegration of the composition by chemical reaction with the metal.
• the agent causes disintegration of the composition by dissolution of the metal.
• the composition is subjected prior to disintegration to a grain-refining heat treatment.
• Such powders are desired at present particularly in the nuclear energy field, especially in the preparation of dispersions in inert matrixes, such as graphite or metal, or in the preparation of agglomerates by compaction.
• inert matrixes such as graphite or metal
• agglomerates by compaction it is desirable to employ substantially spherical particles and rigorously controlled dimensions, for example a diameter of 100 microns. Since at present it is hardly possible to obtain them otherwise than by grinding uranium carbide or the like, previously formed by sintering or fusion, the grinding step represents a considerably energy consumption and does not readily lead to the desired particle size range.
• a metal-ceramic composition that is a metallic ceramic containing the refractory metal compound to be obtained, for instance uranium carbide, and a metal alone or alloyed, namely in this instance uranium, i.e. the base metal of the compound, the disintegration taking place by reason of the chemical or physical action of an external agent (such as a reactant or solvent) and 3,228,748 Patented Jan. 11, 1966 undergoing transformation into powders, from which the desired metal compound is extracted, e.g. by physical or chemical separation.
• an external agent such as a reactant or solvent
• 3,228,748 Patented Jan. 11, 1966 undergoing transformation into powders, from which the desired metal compound is extracted, e.g. by physical or chemical separation.
• the reaction in question gives a mixture in powder form containing both the residue from the reaction with or the dissolution of the metal and also the desired powder, which is separated out.
• Such a process avoids any mechanical grinding treatment. It permits a good particle size to be obtained, particularly if the process includes, as is preferable, a heat treatment for modifying the grain structure prior to disintegration.
• the proportions of the metal compound and of the metal in the initial metal-ceramic composition are desirably chosen in the appropriate manner. Proportions in the range of 60 to for the former and 40 to 5% for the latter are considered appropriate, though these amounts are not to be taken as limiting.
• a cermet or metal-ceramic composition containing uranium monocarbide and uranium metal in the afore-mentioned proportions which correspond to a carbon content of the composition in the range of 3 to 4.4% by weight.
• the carbon content of uranium monocarbide, UC is 4.8%, from which it will be seen that a proportion of 3 to 4.4% of carbon in the composition gives a major amount of UC and a minor amount of uncombined uranium metal.
• uranium and pure carbon are used, for example, in the aforementioned proportions, and are subjected to sintering.
• uranium oxide is used and is reduced by carbon.
• This composition is subjected to a heat treatment for grain-refining or enlarging the particles of uranium carbide, regularising their shape and making their size uniform.
• the heat treatment is effected, for instance, under a vacuum of about 10* to 10* mm. of mercury or in an inert atmosphere for a period of 1 to 8 hours at a temperature in the range of 1200 to 2200 C.
• the disintegration step is effected, for instance by heating the metal-ceramic composition in the presence by hydrogen, under conditions conducive to the formation of uranium hydride.
• This treatment is carried out in a suitable furnace, for example at a temperature in the range of 200 to 300 C. and under a hydrogen pressure of about 1 atmosphere.
• uranium monocarbide and uranium hydride powders forms.
• the mixture then has to be separated into its constituents.
• the separation is effected for example by decantation in a liquid of appropriate density and viscosity or in any other manner, e.g. by centrifuging.
• this separation may be effected directly on the uranium monocarbide and hydride derived from the afore-mentioned treatment or on a mixture of uranium carbide and uranium powder, after decomposition of the uranium hydride.
• uranium nitride powders from a uranium nitride/ uranium metal-ceramic composition examples include uranium silicide (U Si powders from a metal-ceramic composition composed of the compound per se and the eutectic which it forms with uranium.
• uranium nitride powders disintegration occurs, for instance, by the action on theuranium nitride/ uranium composition of normal hydrochloric acid, at a temperature of about 60 C., for example, thus producing uranium chloride which goes into solution.
• the uranium nitride powder forms in this solution.
• the reaction product is then subjected to filtration and the filtrate, namely the nitride powder, is Washed with water, dried with alcohol or acetone and then dried under vacuum.
• uranium silicide action on the eutectic by one of the agents mentioned above for the carbide or the nitride or by some other agent causes decomposition into small particles, While the uranium silicide assumes the form of larger particles. It is thus appropriate to separate the two kinds of particles physically.
• the grain-refining heat treatment should preferably be limited to temperatures in the range of 1000 to 1500 C.
• a process for the production of powders of refractory uranium compounds selected from the group consisting of uranium carbide, uranium nitride and uranium silicide which comprises the steps of forming a mass of a metalceramic composition containing a major proportion of said compound and a minor proportion of uncombined uranium metal as the matrix metal of said mass, heating said composition at a temperature of from 1000 C. to 2200 C.
• a process according to claim 1 in which a metal ceramic composition containing uranium nitride and uranium metal is contacted with hydrochloric acid which chemically reacts with the uranium metal to form uranium nitride powder in solution and the uranium nitride powder is separated by filtration.
• the metalceramic composition initially contains 60 to 95% refractory uranium compound and to 5% uranium metal.
• a process for the preparation of uranium silicide powder which comprises forming a metal-ceramic composition containing uranium silicide and its eutectic with uranium metal, treating the composition with an agent selected from the group consisting of hydrogen and hydrochloric acid to effect chemical reaction with the uranium metal and cause the formation of particles of uranium silicide and physically separating the uranium silicide particles from the other reaction products.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Inorganic Chemistry (AREA)
• Physics & Mathematics (AREA)
• High Energy & Nuclear Physics (AREA)
• General Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Crystallography & Structural Chemistry (AREA)
• Carbon And Carbon Compounds (AREA)
• Manufacture And Refinement Of Metals (AREA)

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Citations (9)

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• 0
  • NL NL272727D patent/NL272727A/xx unknown
• 1960
  • 1960-12-31 FR FR848551A patent/FR1284062A/fr not_active Expired
• 1961
  • 1961-12-15 DE DEC25747A patent/DE1187232B/de active Pending
  • 1961-12-19 GB GB45468/61A patent/GB1005393A/en not_active Expired
  • 1961-12-20 BE BE611776A patent/BE611776A/fr unknown
  • 1961-12-20 CH CH1471061A patent/CH407348A/fr unknown
  • 1961-12-21 US US161276A patent/US3228748A/en not_active Expired - Lifetime
  • 1961-12-29 LU LU41026D patent/LU41026A1/xx unknown

Patent Citations (9)

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