DE102013008854B9 - Graphite powder mixture and process for its preparation - Google Patents

Abstract

Graphite powder, characterized in that the powder is a homogeneous mixture of at least two types of graphite powder, each having a different coefficient of thermal expansion, wherein one graphite cake outweighs quantitatively and the other graphite acts as an additional graphite species, wherein the graphite varieties differ in a form factor FF, which correlates with their thermal expansion coefficient, wherein the form factor FF results in each case from a division of a Siebmaschenweite in microns through which passes a certain percent graphite flake x of this Graphitsorte (dx value), by a at least one SEM image optically determined and computationally averaged thickness c of the SEM Recording visible flakes of graphite, with a small form factor FF correlates with a high coefficient of thermal expansion and a larger form factor FF with a smaller coefficient of thermal expansion.

Description

The invention relates to a graphite powder mixture and a process for its preparation.

Graphite has a hexagonal structure and consists of a sequence of different layers, the so-called graphene layers, which propagate in an ab plane and are superimposed in the c direction and are held together only by weak Van der Waals interactions.

The density of graphite varies greatly depending on the origin and degree of comminution. Due to the layer structure, some properties of graphite are strongly direction-dependent, such as electrical conductivity, thermal conductivity and mechanical properties.

A particular disadvantage of graphite is its low oxidation resistance. It increases with increasing crystallinity of the carbon material.

Refractory shaped products made of graphite powders are z. B. usually in large blocks or shaped stones for z. As furnace linings or as molds or crucibles or as wells and electrodes for the production of aluminum. The raw material is usually calcined natural graphite, which in coarse crystalline platelet form as so-called flake graphite with carbon contents between 86 and 99, in particular between 92 and 98% and particle sizes z. B. between> 200 and <500 microns is used. Natural graphite available on the market comes mainly from deposits in China, Brazil, Norway, Canada, India and North Korea. As a binder for the graphite is in the production of graphite blocks or graphite bricks z. B. coal tar pitch, petrol pitch or resins used and solidified by coking of the binder at higher temperatures to a so-called coke scaffold, the spatial shape of the blocks or stones. A description of the refractory graphite blocks or stones is in "Gerald Routschka / Hartmut Wuthnow, Practical Guide Refractory materials", 5th edition, Vulkan Verlag, 2011, pp. 56-59.

The natural graphite powder available on the market, the z. B. are suitable for refractory products or other graphite products, due to deposits due to particular differences in the dimensions in the flakes, resulting in differences in mechanical properties. In addition to these natural graphites, synthetic graphites are also on the market.

In addition to the graphite refractory products mentioned above, there are other graphite products which, like refractory graphite products, are subject to frequent temperature changes during use. These are z. As bearings and seals, carbon brushes, electrodes or the like. The refractory graphite products, like the other graphite products, have a relatively low reversible thermal expansion compared to other refractory materials. Nevertheless, this can in use, for. B. in a masonry lining of an industrial furnace still be too high and lead to stress cracks and chipping.

The US 2009/0286131 A1 discloses a separator material for polymer electrolyte fuel cells comprising 100 parts by weight of a graphite powder and 10 to 35 parts by weight of a thermosetting resin. The graphite powder is firmly incorporated into the thermosetting resin and prepared by mixing an artificial graphite powder having an average particle diameter A of 1 to 15 μm and a natural graphite powder having an average particle diameter B of A x (2 to 20) μm in a weight ratio of 80 : 20 to 60:40. The releasing material has an electrical resistivity of 0.02 Ωcm or less, a resistance anisotropy ratio (thickness direction / area direction) of two or less and a gas permeability of 10 ^-6 cm ³ / cm ² · min or less. The US 2009/0286131 A1 also relates to a method of making the separator material.

From the US 2009/0057940 A1 For example, a method of recompressing expanded graphite or expanded graphite is known to produce a less anisotropic, flexible graphite foil having an electrical conductivity in the thickness direction of not less than 15 S / cm. According to the method, there is provided a mixture of expanded or expanded graphite flakes and particles of non-expandable graphite or carbon, wherein the particles are present in an amount of from 3 to 70% by weight, based on the total blend weight. The mixture is compressed in at least a first direction at a pressure of 0.04 MPa to about 350 MPa to a first continuous mixture. The first continuous mixture is compressed in a second direction other than the first direction at a pressure sufficient to form the flexible graphite foil having a bulk density of from 0.1 g / cm ² to 2.0 g / cm ² manufacture.

The US 2006/0035085 A1 discloses a highly thermally conductive element comprising a graphite-based matrix and carbon particles dispersed in the graphite-based matrix, wherein the C-axis of the graphite-forming graphene layers are substantially parallel, and wherein the thermal conductivity in a direction perpendicular to the C-axis is 400 to 1000 W / m K is, and wherein the thermal conductivity in a direction parallel to the C-axis direction is 10 to 100 W / m · K.

It is an object of the invention to increase the reversible thermal expansion of graphite powders for use in graphite products of natural graphites and / or synthetic graphites, but in particular to reduce.

This object is achieved by a homogeneous graphite powder mixture of at least two with respect to a particle size parameter different powdered graphite from particular natural occurrence, the reversible thermal expansion of Graphitsortengemisches and resulting graphite product from the difference of the reversible thermal expansion of the two graphites, z. As the two flake graphite results. In this case, the at least two graphite grades are selected on the basis of a different form factor FF, which has previously been determined for the respective graphite species.

With reversible thermal expansion equally the thermal expansion coefficient α is meant, which characterizes the reversible thermal expansion. Not meant is an irreversible stretching and irreversible shrinkage, but the elongation with temperature increase, which goes back equally with temperature lowering.

In the context of the invention, it has been found that the determined maximum or average grain size or other specific grain sizes of a graphite cake are not suitable for correlating with the reversible thermal expansion so that the reversible thermal expansion of the mixture does not occur with a mixture of at least two graphite species of different grain sizes Another is controllable. It has been shown that not every finely divided or coarser graphite grade alike influences the reversible thermal expansion of another graphite species, because the reversible thermal expansion of the graphite does not correlate exclusively with its fineness.

Surprisingly, it was found that in each case a determinable form factor of a graphite cake correlates with its reversible thermal expansion. The form factor is calculated from a determined grain size determined by a sieve analysis and an average calculated from an optical measurement of the thickness of a plurality of flakes of the flake graphite species. The number of flakes to be measured results z. B. from statistical specifications that the expert knows and z. B. the standard ASTM E112 can be seen.

The form factor FF is thus calculated from the following formula: FF = particle size in μm of a certain amount of graphite that passes through a specific sieve (dx value) / average thickness c in μm from an optical measurement of at least one scanning electron micrograph (SEM image)

For example, for a first graphite cake by sieving the sieve is determined in which 90 wt .-% of the graphite cake pass through the sieve (d ₉₀ value). This d ₉₀ value gives z. B. a grain size of 200 microns. By an optical evaluation of at least one SEM image of the graphite, the average thickness c (the average) is determined by measuring the thickness of a plurality of flakes, with z. B. 10 microns. This results in the following value for the form factor FF of this first graphite with FF = d90 value [μm] / c [μm] = 200/10 = 20

If a higher value for the form factor is determined for a second graphite variety from its d ₉₀ value and average thickness c, then the reversible thermal expansion of the first graphite species can be more or less reduced in this mixture by mixing with the first graphite species ,

For it could only be found in the context of the invention that the reversible thermal expansion of a graphite with their form factor correlated by relatively high reversible thermal expansion and a relatively high form factor of a graphite is a relatively low reversible thermal expansion at a relatively low form factor of a graphite.

The difference between two form factors in a graphite cake mixture is expediently at least 10, in particular at least 50, preferably at least 80.

The blended amount of the other graphite, the Zusatzgraphitsorte, depends on the amount of the desired reduction in the reversible thermal expansion of the graphite to be changed, which is without significant influence on other properties of the respective, containing a certain amount of graphite refractory product, eg. B. in which according to the invention now contains a graphite mixture having a reduced reversible thermal expansion corresponding to the Zusatzgraphitsortenmenge. The added amount of Zusatzgraphitsorte is z. B. maximum of 50 wt .-% and at least 3 wt .-% to the graphite mixture and is not dependent on the reversible thermal expansion z. As the refractory product, which is influenced by the graphite mixture addition, because the reduction of the reversible thermal expansion of z. B. refractory product based solely on the reversible thermal expansion of the graphite mixture.

The following clarifies the uselessness of only throughput values d _x . A graphite grade available on the market had a d ₉₀ value of 30 μm and a c value of 0.4 μm. Another places graphite had a d ₉₀ value of 154 microns and a c-value of 2.0 .mu.m. For both graphite grades, 75 and 77 were found to be close to each other, ie both graphite grades show the same effects with respect to the possible reduction of reversible thermal expansion compared with the above calculated form factor of 20, although the d ₉₀ values and the c values are far apart ,

Reference to the drawing, the invention is explained in more detail below by way of example. Show it:

1 a scanning electron micrograph (SEM image) of a commercially available flake graphite powder grade with indications of a few optically measured flake thicknesses;

2 a graph of the correlation between the coefficient of thermal expansion and the shape factor of different Graphitsorten at the respective d ₉₀ value.

The reversible thermal expansion or the coefficient of thermal expansion of a graphite powder is z. B. determined by a cold isostatically pressed graphite test piece is prepared and then the thermal expansion is measured.

For this purpose, a mixture of the graphite with a novolak powder resin plus resin hardener z. For example, hexamethylenetetramine, from 95 Ma.% Graphite and 5 Ma.% Resin including 10 Ma.% Hardener, based on the resin. The mixture is carried out in an intensive mixer (for example, a countercurrent mixer, at 1500 rpm for 4 minutes), after which the crude mixture is filled into a latex mold, the mold is closed with a stopper with a valve, and the crude mixture is evacuated by means of a vacuum pump a cold isostatic pressing and curing of the molding for 2 h at 200 ° C. From the cured molded body, a cylinder is then drilled and sawn with the dimensions d = 40 mm, h = 50 mm.

To determine the thermal expansion of the graphite test specimen of the graphite cylinder is placed in a measuring capsule, which is filled with petroleum coke for protection against combustion of carbon, and for the measurement of thermal expansion of a hood furnace z. B. the company Netzsch used. The prepared measuring capsule is installed in the hood furnace and a load of 0.02 MPa applied and the sample heated to 1500 ° C. The thermal expansion is determined with a recorded strain curve. The calculation of the thermal expansion coefficient α then takes place from the increase in the expansion curve as a function of the temperature, determined on the basis of DIN-EN 993-19.

The SEM image ( 1 ) shows several graphite flakes of the graphite powder of a marketed flake graphite variety, some of which are labeled "GF". In addition, in several graphite flakes, the optical analog ASTM E 112 given specific thickness, the measured point is marked with a dash. The scale of the SEM image is given at the foot of the image with 200 microns. From the thickness measurements results according to ASTM E 112 an average thickness c of rounded 25 microns. The sieve analysis of this graphite grade gave a d ₉₀ value of 400 μm, resulting in a form factor of FF = 16.

Another flake graphite on the market was similarly analyzed giving a molding factor of FF = 94.

A blend of 80% by weight of the first flake graphite and 20% by weight of the second flake weight graphite cake gave a CTE of 10.2 × 10 ^-6 K ^-1 . A mixture of 90% by weight of the first Flake graphite and 10% by weight of the second flake graphite yielded a CTE of 11.9 × 10 ^-6 K ^-1 . A blend of 70% by weight of the first flake graphite and 30% by weight of the second flake graphite yielded a CTE of 8.5 × 10 ^-6 K ^-1 .

This example illustrates that the coefficient of thermal expansion and thus the reversible thermal expansion of a graphite powder grade can be changed in a targeted manner via the form factor FF.

2 shows the correlation of the coefficient of thermal expansion of different flake graphite varieties to the form factor of the graphite species, the values being on a slightly bent connecting line. Shown is the correlation with d ₉₀ values of the flake graphites. The same and also useful for the purposes of the invention correlation lines arise with other d _x values up to z. D ₅₀ values or x values above 90. The higher this pass value, the more accurate the correlation. The d _x value should therefore advantageously be between d ₅₀ and d ₉₅ .

It is expedient to use the same d _x value for the flake graphites to be analyzed, eg. Example, to select the d ₉₀ value for the available flake graphites and the calculated form factor, the additional graphite or the Zusatzgraphitsorten with which the thermal expansion coefficient of a graphite mainly used by mixing a Zusatzgraphitsorte can be clearly controlled.

It is advisable to screen according to ASTM E11-87 or ISO 565.

The graphite powder blends of the present invention are effectively useful in the production of pure graphite products, especially pure refractory graphite products consisting primarily of graphite, such as crucibles, graphite blocks and other graphite components, because by blending at least two different flake graphites, e.g. B. originating from different deposits, flake graphite can be produced with significantly changed reversible thermal expansion. This makes z. B. sense, if you only want to change the reversible thermal expansion of a graphite and the other original properties of graphite products are to remain intact with the same graphite content.

An application of the targeted and effective change of the reversible thermal expansion of a graphite by admixing a determined on the form factor for suitable, other flake graphite is possible for all molded graphite-containing products. In all refractory products, graphite basically influences reversible thermal expansion because of its different reversible thermal expansion compared to other substances or materials it contains. In addition, there is a dependence on the amount of graphite in the refractory graphite product, but different amounts of graphite not only cause different reversible thermal expansion, but also change other essential properties such as cold compressive strength, cold bending strength, modulus of elasticity and thermal shock resistance. The present invention remedy this by now graphite mixtures can be used as graphite additive in the same amount, which change only the reversible thermal expansion, but not the other properties to an unacceptable extent.

It is within the scope of the invention, instead of the d _x value from a screening to evaluate at least one SEM image of a flake graphite by the graph length a and the graphene width b of a statistically sufficient number of flakes optically, z. For example, according to ASTM E112, and these values are averaged in each case and from the averaged values for a and b, the term becomes √ a² + b² calculated as d _x value. This value is divided by the averaged thickness c of the graphite flakes of this graphite variety, which is likewise determined and also from the same SEM image. This results in a form factor FF, which correlates equally with the thermal expansion coefficient or with the reversible thermal expansion as the form factor FF, which is calculated with a d _x value.

It is also within the scope of the invention to use at least one synthetic graphite, in particular as Zusatzgraphitsorte.

• – das Pulver ein homogenes Gemisch aus mindestens zwei Graphitpulversorten mit jeweils unterschiedlichem Wärmeausdehnungskoeffizienten ist, wobei eine Graphitsorte mengenmäßig überwiegt und die andere Graphitsorte als Zusatzgraphitsorte fungiert, und
• – sich die Graphitsorten in einem Formfaktor FF unterscheiden, der mit ihrem Wärmeausdehnungskoeffizienten korreliert, wobei der Formfaktor FF sich jeweils ergibt aus einer Division einer Siebmaschenweite in μm, durch die eine bestimmte prozentuale Graphitflockenmenge x dieser Graphitsorte durchgeht (d_x-Wert), durch eine aus mindestens einer REM-Aufnahme optisch ermittelten und rechnerisch gemittelten Dicke c von auf der REM-Aufnahme sichtbaren Flocken der Graphitsorte, wobei ein kleiner Formfaktor FF mit einem hohen Wärmeausdehnungskoeffizienten und ein größerer Formfaktor FF mit einem kleineren Wärmeausdehnungskoeffizienten korreliert.

A graphite powder according to the invention is characterized in that

• - The powder is a homogeneous mixture of at least two graphite powder varieties, each with different coefficients of thermal expansion, wherein one Graphitsorte quantitatively outweighs and the other Graphitsorte acts as Zusatzgraphitsorte, and
• - The graphite varieties differ in a form factor FF, which correlates with their thermal expansion coefficient, wherein the form factor FF results in each case of a division of a Siebmaschenweite in microns through which a certain percent graphite flake x of this Graphitsorte passes (d _x value), by a from at least one SEM image optically determined and computationally averaged thickness c of visible on the SEM image flakes of graphite, with a small form factor FF with a high coefficient of thermal expansion and a larger form factor FF correlates with a smaller coefficient of thermal expansion.

• – der Formfaktor FF von geeigneten Graphitsorten zwischen 5 und 200, insbesondere zwischen 10 und 100 liegt, (Anspruch 2)
• – x des d_x-Wertes zwischen 50 und 95, insbesondere zwischen 60 und 90 liegt, vorzugsweise 90 ist, (Anspruch 3)
• – die Differenz der Formfaktoren FF (ΔFF) der Graphitsorten des Graphitsortengemisches mindestens 10, insbesondere mindestens 50 und vorzugsweise mindestens 85 beträgt. (Anspruch 4)
• – die Zusatzmenge der Zusatzgraphitsorte z. B. mit dem größeren Formfaktor FF zur Graphitsorte mit dem kleineren Formfaktor FF maximal 50 Gew.-% beträgt und insbesondere zwischen 5 und 30 Gew.-% liegt, (Anspruch 5)

Particularly advantageous is a graphite powder according to the invention, when

• The form factor FF of suitable graphite grades is between 5 and 200, in particular between 10 and 100, (claim 2)
• X is the d _x value between 50 and 95, in particular between 60 and 90, preferably 90, (claim 3)
• - The difference of the shape factors FF (.DELTA.FF) of the graphite varieties of the graphite cake mixture is at least 10, in particular at least 50 and preferably at least 85. (Claim 4)
• - The additional amount of additional graphite z. B. with the larger form factor FF to graphite with the smaller form factor FF is not more than 50 wt .-% and in particular between 5 and 30 wt .-%, (claim 5)

• – sich die Graphitsorten in einem mit ihrem Wärmeausdehnungskoeffizienten korrelierenden Formfaktor FF unterscheiden, wobei die eine Graphitsorte einen niedrigeren Formfaktor FF aufweist und den überwiegenden Bestandteil des Graphitgemisches ausmacht und die andere Graphitsorte einen höheren Formfaktor FF aufweist oder umgekehrt, je nachdem welcher Wärmeausdehnungskoeffizient verändert werden soll, und wobei der Formfaktor FF jeder Graphitsorte vor dem Mischen ermittelt wird, (Anspruch 8)
• – jeder Formfaktor FF wie folgt ermittelt wird (Anspruch 9): Siebung der Graphitsorte und Ermittlung der Maschenweite in μm eines Siebes, das eine bestimmte prozentuale Durchgangsmenge x in Gew.-% durchlässt (d_x-Wert) Ermittlung der aus einer statistisch ausreichenden Anzahl von Messungen von Graphitflocken ermittelten gemittelten Dicke c mit einem optischen Verfahren aus mindestens einer REM-Aufnahme der jeweiligen Graphitsorte Berechnung des Formfaktors FF mit der Formel: FF = dx-Wert / c
• – Graphitsorten mit Formfaktoren FF von mindestens 10, insbesondere von mindestens 50 und vorzugsweise mindestens 100 zur Herstellung von Graphitgemischen verwendet werden, (Anspruch 10)
• – die Maschenweite unter Verwendung von x-Werten zwischen 50 und 95, insbesondere zwischen 60 und 90, vorzugsweise mit 90 ermittelt wird, (Anspruch 11)
• – Graphitsorten für ein Graphitgemisch verwendet werden, deren Differenz zwischen ihren Formfaktoren FF (ΔFF) mindestens 3 und maximal 50 beträgt und insbesondere zwischen 5 und 30 liegt, (Anspruch 12)
• – die Zusatzmenge der Graphitsorte mit dem größeren Formfaktor FF zur Graphitsorte mit dem kleineren Formfaktor FF oder umgekehrt, je nachdem welcher Wärmeausdehnungskoeffizient verändert werden soll, minimal 3 und maximal 50 Gew.-% beträgt und insbesondere zwischen 5 und 30 Gew.-% liegt. (Anspruch 13)

A method according to the invention for reducing the reversible thermal expansion of a graphite powder, in particular natural graphite, in particular usable for refractory shaped graphite products or refractory graphite-containing products, provides for producing and shaping and solidifying a mixture of graphite and at least one binder, the graphite being a mixture is used from at least two types of graphite powder, which differ with their coefficient of thermal expansion, wherein one graphite cake outweighs quantitatively and the other graphite serves as Zusatzgraphitsorte, which is advantageous if

• The graphite grades differ in a form factor FF correlated with their coefficient of thermal expansion, one graphite species having a lower form factor FF and making up the majority of the graphite mixture and the other graphite having a higher form factor FF or vice versa, depending on which coefficient of thermal expansion is to be altered; and wherein the shape factor FF of each graphite is determined before mixing, (claim 8)
• - Each form factor FF is determined as follows (Claim 9): Screening of the graphite and determining the mesh size in microns of a sieve, which passes a certain percentage passage x in wt .-% (d _x value) Determination of a statistically sufficient number of measured thicknesses of graphite flakes determined by means of an optical process from at least one SEM image of the respective graphite species Calculation of the form factor FF by the formula: FF = dx value / c
• - Graphitsorten with form factors FF of at least 10, in particular of at least 50 and preferably at least 100 are used for the production of graphite mixtures, (claim 10)
• The mesh size is determined using x values between 50 and 95, in particular between 60 and 90, preferably 90, (claim 11)
• - Graphitsorten be used for a graphite mixture whose difference between their form factors FF (ΔFF) is at least 3 and a maximum of 50 and in particular between 5 and 30, (claim 12)
• - The additional amount of graphite with the larger form factor FF to the graphite with the smaller form factor FF or vice versa, depending on which coefficient of thermal expansion is to be changed, is at least 3 and at most 50 wt .-% and in particular between 5 and 30 wt .-%. (Claim 13)

Claims (13)

Graphite powder, characterized in that the powder is a homogeneous mixture of at least two types of graphite powder, each having a different coefficient of thermal expansion, wherein one graphite cake outweighs quantitatively and the other graphite acts as an additional graphite species, wherein the graphite varieties differ in a form factor FF, which correlates with their thermal expansion coefficient, wherein the form factor FF results in each case from a division of a Siebmaschenweite in microns through which passes a certain percentage graphite flake x of this Graphitsorte (d _x value), by a at least one SEM image optically determined and computationally averaged thickness c of on the SEM image visible flakes of graphite, with a small form factor FF with a high coefficient of thermal expansion and a larger form factor FF correlates with a smaller coefficient of thermal expansion. Graphite powder according to claim 1, characterized in that the form factor of suitable graphite grades is between 5 and 200, in particular between 10 and 100. Graphite powder according to claim 1 and / or 2, characterized in that x is between 50 and 95 wt .-%, in particular between 60 and 90 wt .-%, preferably 90 wt .-% is. Graphite powder according to one or more of claims 1 to 3, characterized in that the difference of the shape factors FF (.DELTA.FF) of the Graphitsorten the Graphitsortengemisches is at least 10, in particular at least 50 and preferably at least 85. Graphite powder according to one or more of claims 1 to 4, characterized in that the additional amount of graphite with the larger form factor FF to graphite with the smaller form factor FF is at most 50 wt .-%, and in particular between 5 and 30 wt .-%. Graphite powder according to one or more of claims 1 to 5, characterized by a mixture of natural graphite powder and / or synthetic graphite powder varieties. A method for reducing the reversible thermal expansion of a graphite powder, characterized in that a mixture of at least two graphite powder is produced, which differ with their coefficient of thermal expansion, one graphite cake outweighs quantitatively and the other graphite acts as a Zusatzgraphitsorte, - the Graphitsorten in one with their A graphite variety has a lower form factor FF and makes up the majority of the graphite mixture and the other graphite has a higher form factor FF or vice versa, depending on which coefficient of thermal expansion is to be changed, and wherein the form factor FF each Graphitsorte ago In the case of mixing, each form factor FF shall be determined as follows: - Screening of the graphite grade and determination of the mesh size in μm of a sieve containing a certain percentage pass through quantity x in% by weight (dx value) - determination of the average thickness c determined from a statistically sufficient number of measurements of graphite flakes with an optical method from at least one SEM image of the respective graphite species - calculation of the form factor FF with the Formula: FF = dx value / c A method according to claim 7, characterized in that graphite with FF form factors of at least 10, in particular at least 50 and preferably at least 85 are used for the production of graphite mixtures. Method according to one or more of claims 7 and / or 8, characterized in that the mesh size is determined using x values between 50 and 95, in particular between 60 and 90, preferably 90. Method according to one or more of claims 7 to 9, characterized in that graphite grades are used for a graphite mixture whose difference between their shape factors FF (ΔFF) is at least 3 and at most 50 and in particular between 5 and 30. Method according to one or more of claims 7 to 10, characterized in that the additional amount of graphite with the larger form factor FF to the graphite with the smaller form factor FF or vice versa, depending on which coefficient of thermal expansion is to be changed, minimum 3 and maximum 50 wt. %, and in particular between 5 and 30 wt .-% is. Use of a graphite powder according to one or more of claims 1 to 6 for the production of shaped graphite products or molded refractory products or graphite-containing refractory products. Use of a graphite powder prepared according to one or more of claims 7 to 11 for the production of shaped graphite products or shaped refractory products or graphite-containing refractory products.

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