DE1671047A1 - Method and device for treating ceramic materials in a crucible - Google Patents

Description

INTENDED FOR OFFICIAL DISCLOSURE

"« * «« «« "=" ■ "" = «1671Ό47

Dipl.-Ing. Augsburg, the lk. January 1970

Rudolf Busselmeier New version

Patent attorney _ I 1 ■

Augsburg 31 · Rehlingenstrasse 8 ^Az ' ^{: P l6 71} 0 * 7-7- * 5- "

P.O. Box 242
Current account: Munich No. 74539

Patent application

Societe Beige pour I ¹ Industrie Nucleaire BELGONUCLEAIRE SA, 35, Rue des Colonies, Brussels, Belgium

and

Center d ¹ Etude de! '- Energie Nucleaire, Brussels, M

Avenue Eugene Plansky l44, Belgium

Method and device for the treatment of ceramic materials in a crucible

The invention relates to a method for treating ceramic materials in an independent Crucibles, whereby ceramic materials, which have the properties of a semiconductor, heated to high temperatures by induction.

Ceramic materials can either be metallurgically treated, i.e. melted or recrystallized or undergo chemical treatment.

In a known method (see French patent specification 1,053,900), ferromagnetic Material inductively heated in a crucible. A transfer of this only for the heating of ferromagnetic materials known method »on the heating of ceramic materials possesses

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New documents (Art. 1, Paragraph 1, Paragraph 2 Hr. Τ Sentence 3 of the Anderungseee. Ν. 4. b ~ ² "

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the serious disadvantage that the ceramic material to be heated very easily through the crucible material can be contaminated.

The invention has therefore set itself the task of creating a method which has this disadvantage avoids. Ceramic material should therefore be treated in a crucible in such a way that no contamination the ceramic material can be done through the crucible material.

This object is achieved according to the invention

A solved that the crucible cooled during the heating process will.

The outer layer or skin of the ceramic material, which rests against the inner wall of the crucible, is not heated to high temperature and on this In this way a kind of shielding arises; or protective layer between the treated material on the one hand and the crucible on the other "

The method of the invention enables a wide range of ceramic materials to be treated; it is only necessary that these W materials have semiconductor properties in order for them to be

they can be heated inductively.

The inventive method has the essential advantage that ^; that it does not require the choice of a precisely determined frequency for its implementation, but one has a relatively large scope in the choice of the frequency. The frequency of the heating current is to be dimensioned in such a way that the induced currents penetrate deep into the substance to be treated «

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BATH ORIGINAL

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By cooling the crucible, the outer The material skin of the material to be heated is always one Form a shield between the crucible on the one hand and the heated nuclear material on the other. The thickness of this layer or skin can be regulated very easily by varying the cooling intensity will.

"In the method according to the invention, the ceramic material can be used without prior preparation. The melting hearth can even be filled _{with a mass of ceramic material in the form of powder, grains, spheres, fragments, etc.: -Jj |}

The ceramic material can, for example, from the oxides of uranium, plutonium, circonium, of aluminum or thorium, or of the carbides of uranium or plutonium, or else Borides, nitrides »suicides or a partial off a mixture of these substances.

The frequency must be chosen based on the classic formula for induction heating, namely in Depending on the resistance of the substance to be treated, the variability of the same as a function on the temperature, that of the * j | to be treated Mass corresponding diameter, the desired depth of penetration and the intensity of the cooling.

When treating substances whose electrical conductivity is very low at the ambient temperature is, a part of the substance must be brought to a sufficiently high temperature at the beginning of the heating process so that the currents can be induced. This warming can be done with the help of any known Process, for example by thermal radiation or conduction from a metallic,

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removable heat transfer medium, or by adding a component with greater electrical conductivity to the load to be treated. _{In the case of UO 2} , for example, this component can consist of a single crystal of U0_ or several large U0 "crystals adhering to one another, or of substoichiometric uranium oxide powder or metallic uranium dust. Preheating is facilitated by applying a high frequency, which is then replaced by the lower frequency that is suitable for good heating.

Further useful features of the method according to the invention emerge from the subclaims.

In the drawings, FIGS. 1 and 3 show different exemplary embodiments Invention shown, which are described in detail below.

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Here, shown in detail in Fig. 1, for example and in no way limiting the designated 1, in powder form in the crucible 3 introduced UO _2, wherein the crucible is made of silicon dioxide and k is cooled by a water circulation. A heating inductor 5 », which is connected to a high frequency power source of 3.5 MHz, runs coaxially with and outside the crucible 3» The cooled crucible 3 ensures the formation of a solid wall layer 2 of UO ₀ , even if the mass is melted . In fact, the electric current generated in the wall layer 2 is due to the poor conductivity. of the substance very weak at low temperature.

The temperature of the crucible 3 can be varied, and this means that the thickness of the wall layer 2 can be changed.

The crucible 3 can also have two half-shells Chilled metal can be replaced «The transformer effect of the metallic crucible allows it also to use lower frequencies. A high frequency power source of 1 MHz would have been in use of two half-shells an effect that would be comparable to a source of 3i5 MHz, the is used with a crucible made of silicon dioxide.

Fig. 2 shows the application of the method in casting the ceramic material. An opening is provided in the lower portion of the crucible and the molten material can flow through this opening into a mold (not shown). With a second inductor 6, the moment of the flow can be controlled .

When dividing fuel for nuclear

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reactors can use the ceramic fuel material for example on the basis of this principle are poured into the sleeve in such a way that a fuel element is formed.

Fig. 3 shows a continuous melting system for ceramic materials. In this embodiment the substance 1 is moved along the axis * of the cylindrical crucible 3. This movement is possible because the material 1 due to the cooling of the ceramic material after passing through the induction current area contracts. The material 1 emerges continuously or semi-continuously from the TiegeX 3 and can be supported at its lower part e.g. by a plate (not shown) or by any Gripping arrangement are guided.

Various modifications are possible without departing from the scope of the invention. It can in particular the frequency selection to be treated Material to be adapted. Any cooling method can also be used of the crucible, including cooling with the aid of a gaseous medium.

- patent claims -

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Claims (6)

4804/27 / Th / Wa rj Pat ent claims - 1. Process for the treatment of ceramic materials in an independent crucible, being ceramic materials, which have the properties of a semiconductor own, by induction on high temperature ?! are heated, characterized in that that the crucible (3) is cooled during the heating process. 2 * Method according to claim 1, characterized in that the base material of the ceramic material is uranium or plutonium. 3 »Procedure according to one or more of the preceding Claims, characterized in that the substance is heated to its melting point * k. Method according to claim 3, characterized in that the treated substance is cast in a mold. 5. The method according to claim 3 «thereby g e k e η η ζ e i chnet that the substance in such a way Sleeve is poured into that it is a nuclear fuel element represents. 6. The method according to one or more of the preceding claims, characterized in that g e k en η ze i c h η e t, that the fabric is continuous in a cylindrical Crucible is treated and moves along the axis of this crucible 7 · Method according to one or more of the preceding Claims, characterized thereby , v «4, i- 33/1520 1 ^ January 4970 that the base of the container is silicon dioxide ö. The method according to claims 1 to 6, thereby g e indicates that the suspension is dia Material through the incorporation of one or more single crystals or groups of large, one on top of the other " adhering crystals in the batch is favored. 1QSS33 / 1S2Q