KR20190014269A - Highly-durable graphite tray for heat treatment and method for preparing the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a high-durability graphite tray for heat treatment. More specifically, the method for manufacturing a high-durability graphite tray for heat treatment of the present invention can provide a high-durability graphite tray excellent in oxidation stability, which can increase economic efficiency of environmental energy and process energy by recovering and reprocessing graphite processing by-products at a low temperature for re-use.

Description

TECHNICAL FIELD The present invention relates to a high-durability graphite tray for heat treatment and a method for manufacturing the same.

The present invention relates to a method for producing a highly durable graphite tray for heat treatment, and more particularly, to a method for producing a graphite tray which can prevent or minimize breakage or cracking of the graphite compact during carbonization of the graphite compact, And a method for producing the same.

Artificial graphite exhibits excellent performances such as light weight, heat resistance, electrical and thermal conductivity, chemical stability, and high strength, and can be easily processed by mechanical processing. Therefore, it can be used for semiconductors, wall materials of fusion devices, solar cells, anode materials for secondary batteries, And so on. The graphite tray manufactured by processing artificial graphite in the heat treatment tray manufacturing field has an advantage over the conventional metal tray in thermal shock resistance and thermosetting property.

Oxidation stability is a very important evaluation item in graphite trays for heat treatment. Generally, graphite trays are used as receptors for the above materials when heat treatment of metals, ceramics, and semiconductor materials. The heat treatment temperature at which such a graphite tray is used is about 500 ° C to 1000 ° C. Particularly, there is a problem that oxidation of the graphite tray occurs due to atmospheric oxygen or carbon dioxide in the vicinity of 600 ° C, which is a relatively low temperature portion, thereby reducing the durability of the graphite tray. There is a need to improve the durability and oxidation stability of the graphite tray to prolong the life of the graphite tray.

Korean Patent No. 10-1601401

It is an object of the present invention to provide a method for manufacturing a highly durable graphite tray for heat treatment in which cracking or cracking of the graphite compact is prevented or minimized in the process of carbonizing the graphite compact to solve the above problems.

It is also an object of the present invention to provide a highly durable graphite tray for heat treatment having excellent durability and oxidation stability.

In order to solve the above-mentioned problems, the present invention provides a method for manufacturing a high-durability graphite tray for heat treatment.

A method of manufacturing a high-endurance graphite tray for heat treatment according to an embodiment of the present invention includes the steps of: (1) preparing a graphite mixed composition comprising graphite powder and a first binder; (2) molding the graphite mixed composition to produce a graphite molded body; (3) primary carbonizing the graphite molded body; (4) In order to lower the porosity of the primary carbonized graphite molded body, the primary carbonized graphite molded body is impregnated with the impregnant mixed with the second binder and the organic solvent at a weight ratio of 1: 0.8 to 1: 1.2, And pressing; And (5) secondary carbonizing the impregnated graphite molded body to produce a graphite tray.

Further, the graphite powder may be a graphite processing by-product.

The graphite mixed composition may be prepared by mixing the graphite powder and the first binder at a weight ratio of 1: 0.1 to 1: 0.3.

Also, the step (2) may be performed by pressurizing the graphite mixed composition at a pressure of 2000 bar to 4000 bar for 1 minute to 5 minutes.

In addition, the primary carbonization in the step (3) may be performed by heat-treating at a temperature of 900 ° C to 1100 ° C.

In the step (4), the primary carbonized graphite molding is charged into an impregnation device containing the impregnation agent, the pressure is reduced to 1 × 10 ^-3 bar to 1 × 10 ^-4 bar, bar at a pressure of 10 to 60 minutes.

The secondary carbonization in the step (5) may be carried out by heat treatment at a temperature of 1500 ° C to 1900 ° C.

In addition, the first binder and the second binder may be phenol resins.

In addition, the highly durable graphite tray for heat treatment according to an embodiment of the present invention has a receiving portion and exhibits a density of 1.6 g / ml or more.

Also, when the highly durable graphite tray for heat treatment is maintained at a temperature of 600 ° C. for 1 hour in an air atmosphere, the weight reduction rate due to oxidation of the graphite tray may be 1% or less.

According to the present invention, it is possible to prolong the lifetime of the graphite tray by providing a method of manufacturing a graphite tray which can prevent or minimize cracking or cracking of the graphite compact in the process of carbonizing the graphite compact, and has excellent durability and oxidation stability.

1 is a block diagram showing a method of manufacturing a highly durable graphite tray for heat treatment according to an embodiment of the present invention.
2 is a schematic view showing a process of impregnating a graphite molded body according to an embodiment of the present invention.
3 is a photograph of a graphite tray according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

A method of manufacturing a high-endurance graphite tray for heat treatment according to an embodiment of the present invention includes the steps of: (1) preparing a graphite mixed composition comprising graphite powder and a first binder; (2) molding the graphite mixed composition to produce a graphite molded body; (3) primary carbonizing the graphite molded body; (4) In order to lower the porosity of the primary carbonized graphite molded body, the primary carbonized graphite molded body is impregnated with the impregnant mixed with the second binder and the organic solvent at a weight ratio of 1: 0.8 to 1: 1.2, And pressing; And (5) secondary carbonizing the impregnated graphite molded body to produce a graphite tray.

The process for producing the highly durable graphite tray for heat treatment of the present invention will be described step by step.

First, in the manufacturing method of the present invention, the step (1) is a step (S10) of producing a graphite mixed composition comprising graphite powder and a first binder.

The graphite powder may be a graphite processing by-product.

In general, graphite processing by-products may be added to increase the carbon content in steel mill charcoal, or may be used to prepare graphite-added refractories. In addition, some of graphite processing by-products are discarded, though some are added when manufacturing carbon-magnesite bricks. As a method for recycling such graphite processing by-products, a graphite processing by-product can be used as a raw material of the graphite tray. In addition, since graphite processing by-products are recovered and reworked, they can be used economically.

In addition, the first binder may be a known binder capable of granulating the graphite powder without limitation, and may be, for example, a phenolic resin.

The graphite mixed composition may be prepared by mixing the graphite powder and the first binder in a weight ratio of 1: 0.1 to 1: 0.3, preferably 1: 0.2.

If the weight ratio of the graphite powder to the first binder is less than 1: 0.1, it may be difficult to granulate the graphite powder. When the weight ratio of the graphite powder and the first binder is more than 1: 0.3, There is a possibility that the density and durability of the graphite tray produced and produced are lowered.

The graphite powder and the first binder may be mixed using a known mixer, which may be used as a mixer. For example, the mixer may be a pot mill, a ball mill or a rotary mixer, but is not limited thereto.

Next, in the manufacturing method of the present invention, the step (2) is a step (S20) of forming a graphite molded body by molding the graphite mixed composition, wherein the graphite mixed composition has a pressure of 2,000 to 4,000 bar So as to be formed into a desired shape of the graphite compact.

If the graphite mixed composition is pressurized to a pressure of less than 2000 bar, the shape of the graphite molded body may not be maintained. If the pressure is higher than 4000 bar, the graphite molded body may be broken or cracked.

If the pressing time is less than 1 minute, the shape of the graphite molded body may not be maintained, and if it exceeds 5 minutes, the graphite molded body may be broken or cracked.

The molding method of the graphite molded body may be any known method of producing a molded body without limitation, and may be, for example, but not limited to, uniaxial pressing.

Further, the graphite compact may be dried at a temperature of 70 캜 to 90 캜 for 12 hours to 24 hours.

Next, in the production method of the present invention, the step (3) is a step (S30) of primary carbonization of the graphite compact.

The first binder present in the graphite molded body is carbonized through the primary carbonization process, and the carbonized first binder functions to fix particulate graphite powder in a certain form. When the first binder is carbonized, the volatile components of the first binder are removed, and pores are formed in the graphite molded body. The pores formed in the graphite molded body may lower the durability of the graphite tray to be produced, And the secondary carbonization process can reduce the porosity of the graphite compact.

The primary carbonization may be performed by raising the temperature to a temperature of 900 ° C to 1100 ° C at a rate of 1 ° C to 3 ° C per minute and then performing a heat treatment for 0.3 to 2 hours.

If the temperature raising rate is less than 1 ° C, the cost of the process may increase. If the temperature is higher than 3 ° C, the graphite formed body may thermally expand rapidly during the heat treatment to break the graphite formed body, Lt; / RTI > Even if it is not broken or cracked, breakage or cracking may occur in the impregnation and secondary carbonization process described later, and the durability and oxidation stability of the produced graphite tray may be deteriorated.

If the heat treatment temperature of the primary carbonization is less than 900 ° C, the first binder may not be completely carbonized. Accordingly, the remaining first binder may be carbonized in the secondary carbonization process described later, . It is preferable to carbonize all of the first binders in the primary carbonization process since the porosity generated in the secondary carbonization process may lower the density of the graphite tray to be produced and lower the oxidation stability.

If the heat treatment temperature of the primary carbonization exceeds 1100 ° C, the graphite compact may be thermally expanded to break or crack.

If the heat treatment time of the primary carbonization is less than 0.3 hour, there may be a problem that the first binder is not completely carbonized, and if it exceeds 2 hours, the cost of the process may increase.

Further, the primary carbonization may be performed in an inert gas atmosphere such as nitrogen or argon. The reason why the heat treatment is performed in an inert gas atmosphere is that when heat treatment is performed in an atmosphere in which oxygen exists (for example, atmospheric air), impurities and defects may be generated as the graphite molded body is oxidized, .

Next, in the manufacturing method of the present invention, in the step (4), in order to lower the porosity of the primary carbonized graphite molded body, the primary carbonized graphite molded body is mixed with the second binder and the organic solvent at a ratio of 1: 0.8 to 1: 1.2 (S40) in which impregnation is carried out by impregnating the mixed impregnant at a weight ratio of 1: 1 to 1: 1 and then depressurized and pressurized.

The second binder can be any known binder that can be used in impregnation agents without limitation, for example a phenolic resin.

The organic solvent may be an organic solvent capable of dissolving a binder that can be used in the impregnant, and may be, for example, ethanol.

The step (4) is a step of impregnating the impregnant with the pores of the graphite formed body formed in the primary carbonization step in the step (3), thereby improving the density and oxidation stability of the graphite tray produced after the secondary carbonization .

At this time, the weight ratio of the binder and the organic solvent contained in the impregnant may be adjusted according to the thickness, size, or porosity of the impregnated graphite compact.

For example, when a plate type or rod type graphite molded body having a relatively small thickness is impregnated in the impregnant, even if the viscosity of the impregnant is high or the impregnation pressure is low, The pores of the pores can be easily reached.

However, when a block type or tray type graphite molded body having a relatively large thickness is impregnated in the impregnating agent, in order for the impregnating agent to reach the pores inside the graphite shaped body, the viscosity of the impregnating agent is high If the impregnation pressure is low, the impregnation agent may be difficult to reach the pores in the graphite compact.

When the impregnating agent is impregnated into a tray-shaped graphite molded body having a relatively thick thickness, the weight ratio of the binder and the organic solvent contained in the impregnating agent, and the pressure and pressure conditions in the impregnation process are controlled, The impregnating agent can be penetrated into the pores in the molded body.

First, the weight ratio of the binder and the organic solvent contained in the impregnation agent in the step (4) of the present invention will be described.

As the weight ratio of the organic solvent contained in the impregnant increases, the viscosity of the impregnant decreases, so that the impregnant having a low viscosity can be impregnated into the pores of the graphite compact at a relatively low pressure. However, when an impregnant having a relatively high weight ratio of the organic solvent is used, pressure is generated inside the graphite molded body on the vaporization screen in the secondary carbonization process to be described later, and therefore, Cracks may occur in all of them, and the durability and oxidation stability of the graphite tray produced by the cracks may be deteriorated.

On the contrary, as the weight ratio of the binder contained in the impregnant increases, the viscosity of the impregnant becomes higher, so that the impregnant having a high viscosity can be impregnated into the pores of the graphite compact at a relatively high pressure. When the impregnant having a high weight ratio of binder is used, a larger amount of binder is carbonized in the pores of the graphite molded body during the secondary carbonization process to fill the pores of the graphite molded body, thereby improving the density of the graphite tray And the porosity can be lowered. In addition, the graphite tray having a high density and a low porosity can be excellent in oxidation stability because it has a relatively small area in contact with atmospheric oxygen or carbon dioxide. However, when the graphite compact is impregnated with a relatively high pressure, the graphite compact itself can be softened. Therefore, the impregnation process must be performed in a short time. As a result, the impregnation agent does not have sufficient time to be impregnated into the graphite compact there is a problem.

Therefore, in the impregnation process, the impregnation agent having a relatively high viscosity can be continuously delivered to the pores in the tray-shaped graphite compact by continuously performing the depressurization and the pressure impregnation in the impregnation process, The density can be increased and the oxidation stability can be further improved.

Referring to FIG. 2, the impregnation process of step (4) will be described. First, the primary carbonized graphite formed body 10 is charged into the impregnating agent. The primary carbonized graphite molded body 10 may include graphite 11 and pores 12 which may be impregnated with the pores 12 to impregnate a portion of the pores 12 have. The pores 22 of the impregnated graphite molded body 20 may include a portion 22a impregnated with the impregnation agent and a portion 22b impregnated with the impregnation agent. The impregnated portion 22a may be present inside the graphite formed body 20 when the impregnation agent can not reach the inside of the pores 22 due to the viscosity of the impregnating agent. It is necessary to further infiltrate the impregnant into the non-impregnated portion 22a because the impregnated portion 22a may lower the density and oxidative stability of the graphite tray to be produced.

If the viscosity of the impregnant is relatively low, the gas existing in the non-impregnated portion 22a can be easily discharged through the decompression process. However, if the viscosity of the impregnant is high, it may be difficult to discharge the gas. Therefore, the present invention can effectively infiltrate the impregnant into the interior of the graphite molded body through the depressurizing and pressurizing process described later.

Next, the pressure inside the impregnator may be reduced to discharge the gas present in the impregnated portion 22a of the impregnated graphite compact 20 to the outside of the graphite compact 20. So that the impregnant may be further penetrated into the non-impregnated portion 22a. The pores 32 of the graphite compact 30 after decompression may include less impregnated portion 32a and a greater proportion of impregnated portion 32b than before the depressurization process.

Next, the impregnant may be further infiltrated into the non-impregnated portion 32a of the graphite compact 30 by pressurizing the pressure in the impregnator. As shown in FIG. 2, the graphite compact 40 The pores 42 may be filled with an impregnant.

As described above, the production method of the present invention is capable of effectively impregnating an impregnation agent having a relatively high viscosity into the interior of a graphite compact, while suppressing or minimizing the softening of the graphite compact itself by pressurizing it with a relatively low pressure, The density of the graphite tray can be increased and the oxidation stability can be improved.

In one embodiment of the present invention, the impregnator is connected to a vacuum pump capable of reducing the internal pressure of the impregnator and an air compressor capable of pressurizing the internal pressure of the impregnator.

In the method according to the present invention an exemplary heat treatment and durable graphite tray according to the example, will be described in detail the conditions of the impregnation process, and impregnated with impregnating agent containing groups added to the primary carbide graphite shaped article, 1 × 10 ^-3 bar to 1 x 10 < ^-4 > bar, followed by a pressure of from 1.0 bar to 4.0 bar, preferably from 2.5 bar to 3.5 bar for 10 minutes to 60 minutes, preferably from 20 minutes to 40 minutes And may be carried out at least once or more.

If, vacuum pressure is 1 if it exceeds × 10 ^-3 bar, the gas of the impregnated graphite molded body 20 inside the pore 22 may be difficult to be discharged, when the pressure is a reduced pressure of less than 1 × 10 ^-4 bar, impregnation The organic solvent contained in the organic solvent may be rapidly vaporized and the viscosity of the impregnant may be increased.

If the pressing pressure is less than 1.0 bar, the impregnating agent may hardly penetrate into the non-impregnated portion 32a in the graphite molded body 30. If the pressing pressure exceeds 4.0 bar, the graphite molded body itself is softened, There is a problem that the durability of the finally produced graphite tray may be lowered.

If the pressing time is less than 10 minutes, the impregnating agent may hardly penetrate into the non-impregnated portion 32a in the graphite formed body 30. If the pressing time exceeds 60 minutes, the graphite molded body itself is softened, There is a problem that the durability of the graphite tray manufactured by the method of the present invention may be lowered.

Therefore, in order to produce a highly durable graphite tray, it is preferable to carry out the impregnation process satisfying all of the above-mentioned impregnation conditions.

Next, in the manufacturing method of the present invention, the step (5) is a step (S50) of producing a graphite tray by secondary-carbonizing the impregnated graphite compact.

The secondary carbonization in the step (5) may be performed by heat treatment at a temperature of 1500 ° C to 1900 ° C, preferably at 1600 ° C to 1800 ° C.

The secondary carbonization is a step of carbonizing the impregnating agent and the graphite molded body per se which are impregnated into the pores of the graphite compact in the step (4), wherein the organic solvent contained in the impregnant may be vaporized and removed, The binder contained in the impregnating agent is carbonized to fill the pores of the graphite molded body, thereby lowering the porosity of the graphite tray finally produced, thereby increasing the density of the graphite tray and improving the oxidation stability.

Also, as the organic solvent vaporizes in the secondary carbonization process, pressure may be applied to the interior of the graphite compact. When a large amount of an organic solvent is contained in the impregnant, cracks may be generated in the graphite compact during the secondary carbonization, so that the durability and oxidation stability of the finally produced graphite tray may be deteriorated. Therefore, the weight ratio of the organic solvent contained in the impregnant may be controlled as described above.

The highly durable graphite tray for heat treatment manufactured according to the manufacturing method of the present invention has a receiving portion and may have a density of 1.6 g / ml or more.

The graphite trays for heat treatment produced according to the manufacturing method of the present invention can be used as receptors in heat treatment processes of various materials and can be used as receptors for metals, ceramics, and semiconductor materials, for example. Such a heat treatment process is generally operated at a temperature of 1000 ° C or lower, and the graphite tray used in the heat treatment process may be oxidized at 500 ° C to 1000 ° C. Accordingly, in order to confirm the oxidation stability of the graphite tray according to an embodiment of the present invention, the weight reduction rate due to oxidation was measured when it was heat-treated at 600 ° C for 1 hour in an air atmosphere.

When the graphite tray according to an embodiment of the present invention is maintained at a temperature of 600 ° C for 1 hour in an air atmosphere, the reduction rate of weight due to oxidation may be 1% or less. Accordingly, the graphite tray according to the present invention has excellent oxidation stability . ≪ / RTI >

≪ Example 1 >

A graphite mixed composition containing 25 parts by weight of a phenol resin per 100 parts by weight of graphite processing by-products was placed in a molding mold and uniaxially pressed at a pressure of 3000 bar for 5 minutes to prepare a graphite molded body.

The graphite molded body was dried at a temperature of 80 캜 for 18 hours, then heated to 1000 캜 at a rate of 2 캜 / min in a nitrogen atmosphere, and held for 1 hour for primary carbonization.

The impregnant prepared by mixing a phenol resin and ethanol in a weight ratio of 1: 1 was impregnated with a primary carbonized graphite molded body, the pressure inside the impregnator was reduced to 1 × 10 ^-4 bar by using a vacuum pump, Then, the graphite molded body was impregnated with an air compressor through an impregnation process in which the inside of the impregnator was pressurized at a pressure of 3.0 bar and held for 30 minutes.

Next, the impregnated graphite compact was subjected to a secondary carbonization process in which the temperature was raised to 1700 占 폚 at a rate of 2 占 폚 / min in a nitrogen atmosphere, and maintained for 1 hour.

≪ Example 2 >

The graphite molded body produced and primary carbonized in the same manner as in Example 1 was impregnated with an impregnating agent prepared by mixing phenol resin and ethanol in a weight ratio of 1: 1.5. The pressure was reduced under the same conditions as in Example 1, A secondary carbonization process was performed.

≪ Example 3 >

The graphite molded body produced and primary carbonized in the same manner as in Example 1 was impregnated with an impregnating agent prepared by mixing phenol resin and ethanol in a weight ratio of 1: 0.5. The pressure was reduced under the same conditions as in Example 1, A secondary carbonization process was performed.

<Example 4>

The graphite molded body was impregnated with impregnation agent at a pressure of 3.0 bar for 5 minutes, and a secondary carbonization process was carried out under the same conditions as in Example 1.

&Lt; Example 5 >

The graphite molded body was impregnated with the impregnant at a pressure of 3.0 bar for 70 minutes, and a secondary carbonization process was carried out under the same conditions as in Example 1.

&Lt; Example 6 >

The same procedure as in Example 1 was carried out. The graphite compact was impregnated with the impregnant at a pressure of 5.0 bar for 30 minutes, and a secondary carbonization process was carried out under the same conditions as in Example 1.

&Lt; Example 7 >

The graphite compact was impregnated with impregnation agent at a pressure of 0.5 bar for 30 minutes, and a secondary carbonization process was performed under the same conditions as in Example 1.

&Lt; Comparative Example 1 &

The graphite molded body produced and primary carbonized in the same manner as in Example 1 was impregnated with an impregnating agent prepared by mixing phenol resin and ethanol in a weight ratio of 1: 1, and the pressure inside the impregnator was adjusted to 1 x 10 ^-4 bar The pressure was reduced by using a vacuum pump, and a secondary carbonization process was carried out under the same conditions as in Example 1. [

&Lt; Comparative Example 2 &

The graphite molded body produced and primary carbonized in the same manner as in Example 1 was impregnated with an impregnant prepared by mixing phenol resin and ethanol in a weight ratio of 1: 1, the pressure inside the impregnator was increased to 3.0 bar, Min, the secondary carbonization step was carried out under the same conditions as in Example 1.

&Lt; Comparative Example 3 &

The same procedure as in Example 1 was carried out, but the impregnation step was not carried out.

<Experimental Example 1> Density Measurement

Graphite specimens according to Examples 1 to 7 and Comparative Examples 1 to 3 were prepared in the form of prisms each having a width of 2 cm, a thickness of 2 cm and a length of 10 cm. The graphite test piece thus prepared is dried in a drying apparatus at (110 ± 5) ° C. for 2 hours, and then cooled to room temperature in a desiccator. After the weight of the cooled graphite specimen was measured, the graphite specimen was again dried in the drying apparatus for 1 hour, cooled to room temperature in a decigerator and weighed. The drying and cooling process was repeated until the weight of the graphite test piece became constant. When the weight of the graphite test piece became constant, the density of the graphite test piece was finally measured by calculating the volume of the graphite test piece.

&Lt; Experimental Example 2 > Measurement of mechanical strength

Graphite specimens according to Examples 1 to 7 and Comparative Examples 1 to 3 were prepared in the form of prisms each having a width of 2 cm, a thickness of 2 cm and a length of 10 cm. The mechanical strength of the prepared graphite test piece was measured using a universal material tester (8801 Series, Instron).

Experimental Example 3 Evaluation of Oxidation Stability

 The graphite test pieces prepared according to Examples 1 to 7 and Comparative Examples 1 to 3 were maintained at a temperature of 600 DEG C for 1 hour in an air atmosphere, and then the weight reduction ratio (%) of the graphite test pieces was measured. The weight reduction rate (%) is calculated by the following equation.

[Equation 1]

Weight reduction rate (%) = 100- (Weight after oxidation (g) / Weight before oxidation (g) x 100)

Impregnation process conditions Evaluation of physical properties and oxidation stability Weight ratio of binder and solvent Decompression
pressure
(bar) Pressure
pressure
(bar) Pressure
time
(min) density
(g / ml) Mechanical
burglar
(MPa) weight
Reduction rate
(%) Example 1 1: 1 1 x 10 ^-4 3 30 1.67 36 0.51 Example 2 1: 1.5 1 x 10 ^-4 3 30 1.59 29 0.88 Example 3 1: 0.5 1 x 10 ^-4 3 30 1.58 28 0.85 Example 4 1: 1 1 x 10 ^-4 3 5 1.60 29 0.81 Example 5 1: 1 1 x 10 ^-4 3 70 1.66 31 0.67 Example 6 1: 1 1 x 10 ^-4 5 30 1.65 32 0.68 Example 7 1: 1 1 x 10 ^-4 0.5 30 1.60 30 0.81 Comparative Example 1 1: 1 1 x 10 ^-4 - - 1.57 28 0.86 Comparative Example 2 1: 1 - 3 30 1.59 28 0.90 Comparative Example 3 - - - - 1.53 24 5.76

Table 1 shows the impregnation process conditions of the graphite test pieces prepared according to Examples 1 to 7 and Comparative Examples 1 to 3 and the results of evaluation of physical properties and oxidation stability according to Experimental Examples 1 to 3 .

The graphite test pieces according to Example 1 were the same as the graphite test pieces according to Examples 2 and 3 except that the impregnating process conditions were the same and the weight ratios of the binder and the solvent contained in the impregnant were different. The density was higher than that of the test piece and the mechanical strength was excellent. In the evaluation of the oxidation stability, the weight reduction rate was 0.51%, which was lower than that of the graphite test pieces according to Examples 2 and 3.

The graphite test piece according to Example 2 was impregnated with impregnant having a weight ratio of solvent to binder (1: 1.5) higher than that of Example 1. If the weight ratio of the solvent is high, the impregnating agent may easily penetrate into the graphite compact in the impregnation process. However, as the solvent vaporizes in the secondary carbonization process, the porosity of the graphite test piece according to Example 2 is increased. Accordingly, the density and the mechanical strength of the graphite test piece according to Example 2 are lower than those of the graphite test piece , Respectively. Also, as the porosity of the graphite test piece according to Example 2 was increased, the weight reduction rate due to oxidation was 0.88%, which is higher than that of the graphite test piece according to Example 1 (0.51%).

The graphite test piece according to Example 3 was impregnated with the impregnating agent in which the weight ratio of the solvent to the binder (1: 0.5) was lower than that of Example 1. When the weight ratio of the solvent is low, since the impregnation agent is hardly penetrated into the graphite compact in the impregnation process, the porosity of the graphite test piece according to Example 3 is increased as compared with that of Example 1, It is considered that the density and the mechanical strength of the graphite test piece were measured to be lower than that of the graphite test piece according to Example 1. [ Further, as the porosity of the graphite test piece according to Example 3 was increased, it was judged that the weight reduction rate due to oxidation was 0.85%, which was higher than that of the graphite test piece according to Example 1 (0.51%).

Next, description will be made for Examples 1, 4 and 5 in which the weight ratios of the binder and the solvent contained in the impregnant are the same and the pressurizing time is different among the impregnating process conditions. The graphite test piece according to Example 1 The density and the mechanical strength of the graphite test pieces according to Examples 4 and 5 were higher than those of the graphite test pieces according to Examples 4 and 5, and the weight reduction rate was also lower in the evaluation of the oxidation stability.

The graphite test piece according to Example 4 was subjected to the pressing process during the impregnation process for a relatively short time (5 minutes) as compared with Example 1. The porosity of the graphite test piece according to Example 4 is increased as compared with that of Example 1, so that the density and the density of the graphite test piece according to Example 4 are increased, It is considered that the mechanical strength was lower than that of the graphite test piece according to Example 1. [ Further, as the porosity of the graphite test piece according to Example 4 was increased, it was judged that the weight reduction rate due to oxidation was 0.81%, which was higher than that of the graphite test piece (0.51%) according to Example 1.

The graphite test piece according to Example 5 was subjected to the pressurizing process during the impregnation process for a relatively long time (70 minutes) as compared with Example 1. If the pressing time is long, the impregnation agent may easily penetrate into the pores of the graphite shaped body, but the graphite shaped body may be softened or a crack may be generated in the graphite shaped body during the impregnation process. Although the density (1.66 g / ml) of the graphite test piece according to Example 5 is close to the density (1.67 g / ml) of the graphite test piece according to Example 1, the mechanical strength of the graphite test piece according to Example 5 ) Is relatively lower than the mechanical strength (36 MPa) of the graphite test piece according to Example 1. As a result, it can be seen that when the pressing time is prolonged, the mechanical strength of the graphite test piece to be produced may be lowered. The weight reduction rate of the graphite test piece according to Example 5 is 0.67% and the weight reduction rate of the graphite test piece according to Example 5 is higher than that of the graphite test piece according to Example 1, It was judged that the weight reduction rate was increased due to the flow of gas into the cracks in the evaluation of the oxidation stability due to the occurrence of cracks in the graphite compact.

Next, Examples 1, 6 and 7 in which the weight ratios of the binder and the solvent contained in the impregnant are the same and the pressing pressures of the impregnating process conditions are different will be described.

The graphite test piece according to Example 6 was subjected to a pressurization process during the impregnation process at a relatively higher pressure (5 bar) than that in Example 1. If the pressing pressure is high, the impregnation agent may easily penetrate into the pores of the graphite compact, but the graphite compact may be softened during the impregnation process or a crack may be generated in the graphite compact. Although the density (1.65 g / ml) of the graphite test piece according to Example 6 is close to the density (1.67 g / ml) of the graphite test piece according to Example 1, the mechanical strength of the graphite test piece according to Example 6 ) Is relatively lower than the mechanical strength (36 MPa) of the graphite test piece according to Example 1. As a result, it can be seen that when the pressurizing pressure is high, the mechanical strength of the graphite test piece to be produced may be rather lowered. The weight reduction rate of the graphite test piece according to Example 6 was 0.68% and the weight reduction rate of the graphite test piece according to Example 6 was higher than that of the graphite test piece according to Example 1 It is judged that the weight reduction rate is increased due to the introduction of the gas into the crack in the evaluation of the oxidation stability due to the occurrence of the crack in the graphite compact during the impregnation process.

The graphite test piece according to Example 7 was subjected to a pressurizing process during the impregnation process at a relatively lower pressure (0.5 bar) than that in Example 1. The porosity of the graphite test piece according to Example 7 is higher than that of Example 1 because the impregnation agent is less likely to penetrate into the pores in the graphite molded body. Accordingly, the density and mechanical It is considered that the strength was lower than that of the graphite test piece according to Example 1. Further, as the porosity of the graphite test piece according to Example 7 increased, the weight reduction rate due to oxidation was 0.81%, which is higher than the weight reduction rate (0.51%) of the graphite test piece according to Example 1.

Next, Comparative Example 1 to Comparative Example 3 in which the impregnation step is not performed or the impregnation step is performed but only the depressurization or pressurization step is performed will be described.

The density and the mechanical strength of the graphite test piece according to Comparative Example 1 were measured to be lower than that of the graphite test piece according to Example 1, It is judged that it was not penetrated into the pores of the molded body.

In addition, the graphite test piece according to Comparative Example 2 was manufactured by performing the impregnation process but only the pressurizing process, and the graphite test piece according to Comparative Example 2 had higher density and mechanical strength than the graphite test piece according to Example 1, The strength was measured low.

The graphite test piece according to Comparative Example 3 was produced without the impregnation step, and the graphite test piece according to Comparative Example 3 showed significantly lower density and mechanical strength than the test piece according to Example 1, (5.76%) which is very large.

Mechanical density and mechanical stability and oxidation stability of the graphite tray can be improved by simultaneously performing the depressurization process and the pressure impregnation process in the production of the graphite tray. It is important to determine the physical properties and stability of the tray.

Therefore, a graphite tray having high oxidation stability can be provided through the method for producing a highly durable graphite tray for heat treatment according to the present invention, and a photograph of the graphite tray according to one embodiment of the present invention is shown in FIG.

In the present invention, "oxidation stability" means a property of not being oxidized when the graphite tray is heated in an atmospheric environment, and the lower the weight reduction rate, the better the oxidation stability.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

10: Graphite molded body
11: graphite
12: Engineering
20: impregnated graphite shaped body
22: Porosity of impregnated graphite shaped body
22a, 32a: a portion not impregnated
22b, 32b: impregnated part
30: Graphite molded article after decompression
32: Porosity of graphite formed body after decompression
40: Graphite formed body after pressurization
42: Porosity of graphite formed body after pressurization

Claims (10)

(1) preparing a graphite mixed composition comprising graphite powder and a first binder;
(2) molding the graphite mixed composition to produce a graphite molded body;
(3) primary carbonizing the graphite molded body;
(4) In order to lower the porosity of the primary carbonized graphite molded body, the primary carbonized graphite molded body is impregnated with the impregnant mixed with the second binder and the organic solvent at a weight ratio of 1: 0.8 to 1: 1.2, And pressing; And
(5) secondary carbonizing the impregnated graphite molded body to produce a graphite tray;
Wherein the high-strength graphite tray is made of a metal. The method according to claim 1,
Wherein the graphite powder is a by-product of graphite processing. The method according to claim 1,
Wherein the graphite mixed composition is prepared by mixing the graphite powder and the first binder in a weight ratio of 1: 0.1 to 1: 0.3. The method according to claim 1,
Wherein the step (2) is performed by pressing the graphite mixed composition at a pressure of 2000 bar to 4000 bar for 1 minute to 5 minutes. The method according to claim 1,
Wherein the primary carbonization in the step (3) is performed by heat treatment at a temperature of 900 to 1100 占 폚. The method according to claim 1,
In the step (4), the primary carbonized graphite molded body is charged into an impregnation device containing the impregnation agent, the pressure is reduced to a pressure of 1 × 10 ^-3 bar to 1 × 10 ^-4 bar and then a pressure of 1.0 bar to 4.0 bar Wherein the pressurization is performed at least once for 10 minutes to 60 minutes under pressure. The method according to claim 1,
Wherein the secondary carbonization in the step (5) is performed by performing a heat treatment at a temperature of 1500 to 1900 占 폚. The method according to claim 1,
Wherein the first binder and the second binder are phenolic resins. High durability graphite tray for heat treatment with receptacles and density greater than 1.6 g / ml. 10. The method of claim 9,
Resistant graphite tray for heat treatment having a weight reduction rate of 1% or less by oxidation of the graphite tray when maintained at a temperature of 600 ° C for 1 hour in an air atmosphere.

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