KR102014367B1 - Bulk graphite composite and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a bulk graphite composite and a method for producing the same, and more particularly, to a bulk graphite composite having excellent bending strength and excellent electrical properties without a peeling phenomenon in the composite and a method for producing the same.

Description

Bulk graphite composite and manufacturing method thereof

The present invention relates to a bulk graphite composite and a method for producing the same, and more particularly, to a bulk graphite composite having excellent bending strength and excellent electrical properties without a peeling phenomenon in the composite and a method for producing the same.

Carbon is a chemically stable element that plays an important role in the mechanical and chemical industries, having both physically metallic and ceramic properties and having van der Waals bonds in the c-axis direction, perpendicular to a, On the b side, it is covalently bonded and has a characteristic of showing large anisotropy. In particular, it is considered to be a material excellent in lubricity, heat resistance, thermal shock resistance, thermal conductivity, corrosion resistance, and the like, which are not found in metals and ceramics. In order for the carbon material to be used as a mechanical seal, it is required to have high density and maintain airtightness and to have excellent friction stability.

Bulk graphite is one of the most important high temperature materials because of its excellent thermal and physical properties. However, due to the nature of the bulk graphite complex or large shape of the product causes a variety of problems during processing and manufacturing, as a way to compensate for this problem, research on the bonding technology is in progress.

Conventionally, riveting, bolting, welding and brazing have been used for joining carbon materials. However, the riveting and bolting method punctures the material, exerting excessive pressure, which can reduce the bonding force. The method of welding and brazing requires high cost metals for surface activation of carbon materials. Accordingly, studies to improve the bonding properties of carbon materials are actively underway.

Recently, the high temperature bonding method has emerged as one of the most promising methods because it can transfer the load through the entire joint surface as compared to the simple process. Conventional high temperature binders have been used mainly for inorganic binders, especially ceramic raw materials, for heat resistance, but inorganic high temperature adhesives have a weak bonding strength, are used in combination with other bonding methods, and are limited in size.

Accordingly, there is an urgent need to study a bulk graphite composite having excellent bending strength and excellent electrical properties without peeling phenomenon in the composite.

KR 10-2004-0043528 A

The present invention has been made to solve the above-mentioned problems, the problem to be solved by the present invention is to provide a bulk graphite composite and a method for producing the same, which has excellent peeling strength and excellent electrical properties without peeling phenomenon in the composite. have.

The present invention to solve the above problems, (1) preparing a binder comprising a phenolic resin and an organic solvent; (2) mixing the graphite powder and the binder to prepare a paste for reinforcing strength; (3) treating the strength reinforcing paste in bulk graphite; (4) curing the strength reinforcing paste treated in bulk graphite; And (5) bonding the bulk graphite and the cured strength reinforcing paste through a carbonization process.

According to an embodiment of the present invention, the binder may include a phenolic resin and an organic solvent in a weight ratio of 1: 0.1 to 10.

In addition, the graphite powder of step (2) may be at least one powder selected from the group consisting of earth graphite, artificial graphite and natural graphite.

In addition, the mixing of the step (2) may be performed by stirring the graphite powder and the binder in a volume ratio of 1: 0.8 to 10, for 3 to 13 hours.

In addition, the step (3) may be performed by applying a strength reinforcing paste to the bulk graphite, pressurized at a pressure of 2 to 25 MPa.

In addition, the step (4) may be performed for 0.5 to 2.5 hours at 70 ~ 120 ℃.

In addition, the step (5) may be performed at 600 ~ 1200 ℃ 0.5 ~ 3.5 hours.

In addition, the phenolic resin may be powdery.

In addition, the organic solvent may include one or more selected from the group consisting of ethanol, methanol, acetone, formaldehyde and hexamethylenetetramine.

On the other hand, the present invention provides a bulk graphite composite prepared by the above-described manufacturing method.

According to one embodiment of the present invention, the bulk graphite composite may have a bending strength of 6 to 46 MPa.

In addition, the bulk graphite composite may have a specific resistance of 9 to 14 μΩ · m.

The bulk graphite composite of the present invention exhibits no effect of peeling in the composite and excellent bending strength and excellent electrical properties.

1 is a process flow diagram of a method for producing a bulk graphite composite according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Bulk graphite conjugate according to an embodiment of the present invention, as shown in Figure 1, (1) preparing a binder comprising a phenolic resin and an organic solvent (S1); (2) mixing the graphite powder and the binder to produce a strength reinforcing paste (S2); (3) treating the strength reinforcing paste in bulk graphite (S3); (4) curing the strength reinforcing paste treated in the bulk graphite (S4); And (5) bonding the bulk graphite and the cured strength reinforcing paste through a carbonization process (S5).

First, (1) step (S1) of preparing a binder containing a phenolic resin and an organic solvent will be described.

The phenolic resin may be used without limitation as long as it is a phenolic resin that can be used to prepare a binder in the art, preferably one selected from the group consisting of novolak-based, resol-based, alkylphenol-based and rosin-modified systems. The above can be used, More preferably, a novolak system or a resol system can be used. In addition, the shape of the phenolic resin is not limited as long as it is a phenolic resin that can be used to prepare a binder commonly in the art, and preferably a phenolic resin in powder form may be used.

In addition, the organic solvent may be used without limitation as long as it is an organic solvent that can be used to prepare a binder in the art, preferably one selected from the group consisting of ethanol, methanol, acetone, formaldehyde and hexamethylenetetramine. The above can be used, More preferably, 1 or more types chosen from the group which consists of ethanol and methanol can be used.

On the other hand, the binder may include a phenolic resin and an organic solvent in a weight ratio of 1: 0.1 to 10, preferably in a weight ratio of 1: 0.1 to 9. If the weight ratio of the phenolic resin and the organic solvent is less than 1: 0.1, the problem of poor durability of the bulk graphite composite may occur, and if the weight ratio of the phenolic resin and the organic solvent exceeds 1:10 to the desired level. There may be a problem that the bending strength of the bulk graphite composite is not improved.

Next, (2) step (S2) of mixing the graphite powder and the binder to prepare a paste for strength reinforcement;

The graphite powder may be used without limitation as long as it is a graphite powder commonly used in the art, preferably one or more selected from the group consisting of earth graphite, artificial graphite, and natural graphite.

On the other hand, the mixing of step (2) can be used without limitation, if the conditions are used when preparing a paste in the art, preferably graphite powder and the binder in a volume ratio of 1: 0.8 to 10, 3 ~ For 13 hours, more preferably, the graphite powder and the binder may be performed by stirring for 4 to 12 hours at a volume ratio of 1: 1 to 9. If the volume ratio of the graphite powder and the binder is less than 1: 0.8, the electrical characteristics of the bulk graphite composite may be poor, and if the volume ratio is greater than 1:10, the bending strength of the bulk graphite composite may be poor. have. In addition, if the mixing time is less than 4 hours may cause a problem that the graphite powder is not uniformly dispersed, if more than 13 hours may cause a problem of reaggregation of the graphite powder.

Next, (3) step (S3) of treating the strength reinforcing paste to bulk graphite will be described.

The bulk graphite may be used without limitation as long as it is a bulk graphite that can be commonly used in the art, and preferably may be isotropic bulk graphite prepared through isotropic molding.

On the other hand, step (3) may be performed by applying a strength reinforcing paste to the bulk graphite, and pressurized at a pressure of 2 to 25 MPa, preferably at a pressure of 3 to 23 MPa. After applying the strength reinforcing paste to the bulk graphite, the strength reinforcing paste may be easily fixed to the surface and the pores of the bulk graphite by performing the pressing process. If the pressurization pressure is less than 2 MPa, the strength reinforcing paste is not fixed to the bulk graphite, and thus the bending strength may not be good. If the pressure exceeds 25 MPa, there is a problem in the durability of the bulk graphite composite. May occur.

Next, step (4) (S4) of curing the strength reinforcing paste treated in bulk graphite will be described.

The curing of step (4) can be used without limitation as long as it is a condition for curing a paste containing a phenolic resin in the art, preferably at 70 ° C. to 120 ° C. for 0.5 to 2.5 hours, more preferably. May be performed at 75 ° C. to 115 ° C. for 1 to 2 hours. If the curing temperature is less than 70 ℃ or the curing time is less than 0.5 hours, there may be a problem that the durability of the bulk graphite composite is lowered as the uncured strength reinforcing paste remains, the curing temperature exceeds 120 ℃ or curing If the time exceeds 2.5 hours, problems of swelling and swelling may occur.

Next, (5) step (S5) of bonding the bulk graphite and the cured strength reinforcing paste through the carbonization process;

The carbonization of the step (5), can be used without limitation as long as the conditions in the art can be carbonized conventionally, preferably can be carried out at 600 ℃ to 1200 ℃ for 0.5 to 3.5 hours, more preferably May be performed at 700 ° C. to 1100 ° C. for 1 to 3 hours. If the temperature of the carbonization is less than 600 ℃ or the carbonization time is less than 0.5 hours, the bonding strength between the bulk graphite and the hardened strength reinforcing paste is not at the desired level, the problem that the bending strength of the bulk graphite composite is lowered If the temperature of the carbonization is more than 1200 ℃ or the time of the carbonization is more than 3.5 hours may cause problems of poor durability of the bulk graphite composite.

On the other hand, the present invention provides a bulk graphite composite prepared by the above-described manufacturing method.

The bulk graphite composite may have a bending strength of 6 to 46 MPa, preferably, a bending strength of 6.8 to 44.6 MPa. As the bending strength of the bulk graphite composite satisfies the above range, it may exhibit excellent thermal and physical properties.

In addition, the bulk graphite composite may have a specific resistance of 9 to 14 μΩ · m, preferably 10.08 to 13.29 μΩ · m. Resistivity refers to the resistance per unit length per unit area inherent to the material. Since the resistivity is a material property of electron movement, the specific resistance has a unique value for each material. When electrons pass through the material, the collision speed with the surroundings causes the moving speed to fall within a certain value range, and the average of these speeds is constant for each material, which is the property of the material. It is the resistivity that hinders the movement of electrons in inverse proportion to this average speed. The average velocity of electrons varies with temperature, and the resistivity also depends on temperature, which is proportional to temperature in the case of a conductor and inversely proportional to temperature in the case of a semiconductor. In general, the resistance R is given by R = ρ L / S when the material of material with specific resistance ρ is S and the length is L.

As the specific resistance of the bulk graphite composite satisfies the above range, it may exhibit excellent electrical characteristics.

On the other hand, the bulk graphite composite according to the present invention does not occur peeling phenomenon in the composite, exhibits excellent bending strength and excellent electrical properties.

Although the present invention will be described in more detail with reference to the following examples, the following examples are not intended to limit the scope of the present invention, which will be construed as to aid the understanding of the present invention.

[ Example ]

Example  One: Bulk graphite  Preparation of the complex

(1) Strength reinforcement Paste  Produce

A binder was prepared by mixing phenolic resin (CB-8081, Gangnam Chemical) and ethanol at a weight ratio of 1: 5, and the earthy graphite powder (AOP, general purpose firm) and the prepared binder at a weight ratio of 1: 5.5 for 8 hours. By stirring, a strength reinforcing paste was prepared.

 (2) Bulk graphite  Composite manufacturing

Apply the strength reinforcing paste to bulk graphite (G347, Tokai carbon), apply pressure of 13 MPa to fix the reinforcing reinforcement paste on the bulk graphite, and fix the reinforcing reinforcement paste to the bulk graphite at 100 ° C for 1.5 After drying and curing for a period of time, a carbonization process was performed at a nitrogen atmosphere and at 900 ° C. for 2 hours to bond the bulk graphite and the cured strength reinforcing paste to prepare a bulk graphite composite.

Example  2 to 21 and Comparative example  1 to 3

Manufactured in the same manner as in Example 1, except for the type of graphite powder, the weight ratio of the phenolic resin and the organic solvent, the volume ratio of the graphite powder and the binder, the pressure, the curing process and the carbonization process conditions, such as Table 1 to Table 5 Bulk graphite composites were prepared.

Comparative example  4

Prepared in the same manner as in Example 1, but the boron carbide (B ₄ C) powder was stirred with a phenol resin to prepare a bulk graphite composite by the paste manufacturing method.

< Experimental Example >

The physical properties of the bulk graphite composites prepared through the examples and the comparative examples were measured and shown in Tables 1 to 5 below.

One. Bending strength  Measure

The bulk graphite composite prepared in the above Examples and Comparative Examples was molded to a thickness of 1 cm, and the bending strength was measured through a three-point bending test method at a speed of 1 mm / min using a universal testing machine (i-50, EXEL LAB). Measured.

2. Resistivity Measurement

The specific resistance of the bulk graphite composites prepared in Examples and Comparative Examples was measured by a voltage drop method using a current amount measured by applying a voltage to the composite.

3. Durability Rating

Durability was evaluated for the bulk graphite composites prepared through the above Examples and Comparative Examples.

At this time, when there is no abnormality as a result of evaluation, (circle), when any abnormality generate | occur | produces, such as peeling of a paste and damage of a bulk graphite composite, it was shown by x.

division Example 1 Example 2 Example 3 Example 4 Example 5 Binder manufacturing Phenolic Resin and Organic Solvent Weight Ratio 1: 5 1: 0.05 1: 9 1:12 1: 5 Strength reinforcing paste manufacturing Graphite Powder Type Earth Graphite Earth Graphite Earth Graphite Earth Graphite Artificial graphite Volume ratio of graphite powder and binder 1: 5.5 1: 5.5 1: 5.5 1: 5.5 1: 5.5 Strength reinforcement paste treatment Pressure (MPa) 13 13 13 13 13 Curing step Temperature (℃) 100 100 100 100 100 Carbonization stage Temperature (℃) 900 900 900 900 900 Bending strength (MPa) 44.6 42.8 21.9 5.6 43.9 Specific resistance (μΩm) 11.12 11.7 11.52 11.54 11.13 Durability rating ○ × ○ ○ ○

division Example 6 Example 7 Example 8 Example 9 Example 10 Binder manufacturing Phenolic Resin and Organic Solvent Weight Ratio 1: 5 1: 5 1: 5 1: 5 1: 5 Strength reinforcing paste manufacturing Graphite Powder Type Natural graphite Earth Graphite Earth Graphite Earth Graphite Earth Graphite Volume ratio of graphite powder and binder 1: 5.5 1: 0.5 1: 1 1: 1.5 1: 9 Strength reinforcement paste treatment Pressure (MPa) 13 13 13 13 13 Curing step Temperature (℃) 100 100 100 100 100 Carbonization stage Temperature (℃) 900 900 900 900 900 Bending strength (MPa) 44.1 38.8 32.2 39.1 22.3 Specific resistance (μΩm) 11.17 16.9 13.29 11.91 10.08 Durability rating ○ ○ ○ ○ ○

division Example 11 Example 12 Example 13 Example 14 Example 15 Binder manufacturing Phenolic Resin and Organic Solvent Weight Ratio 1: 5 1: 5 1: 5 1: 5 1: 5 Strength reinforcing paste manufacturing Graphite Powder Type Earth Graphite Earth Graphite Earth Graphite Earth Graphite Earth Graphite Volume ratio of graphite powder and binder 1:12 1: 5.5 1: 5.5 1: 5.5 1: 5.5 Strength reinforcement paste treatment Pressure (MPa) 13 One 3 23 26 Curing step Temperature (℃) 100 100 100 100 10 Carbonization stage Temperature (℃) 900 900 900 900 900 Bending strength (MPa) 4.8 5.2 6.8 44.2 48.7 Specific resistance (μΩm) 8.87 11.49 11.7 11.56 12.1 Durability rating ○ ○ ○ ○ ×

division Example 16 Example 17 Example 18 Example 19 Example 20 Binder manufacturing Phenolic Resin and Organic Solvent Weight Ratio 1: 5 1: 5 1: 5 1: 5 1: 5 Strength reinforcing paste manufacturing Graphite Powder Type Earth Graphite Earth Graphite Earth Graphite Earth Graphite Earth Graphite Volume ratio of graphite powder and binder 1: 5.5 1: 5.5 1: 5.5 1: 5.5 1: 5.5 Strength reinforcement paste treatment Pressure (MPa) 13 13 13 13 13 Curing step Temperature (℃) 60 130 100 100 100 Carbonization stage Temperature (℃) 900 900 500 700 1100 Bending strength (MPa) 38.7 5.3 5.1 21.7 39.6 Specific resistance (μΩm) 12.21 11.98 11.82 11.09 11.16 Durability rating × × ○ ○ ○

division Example 21 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Binder manufacturing Phenolic Resin and Organic Solvent Weight Ratio 1: 5 1: 5 1: 5 1: 5 1: 5 Strength reinforcing paste manufacturing Graphite Powder Type Earth Graphite Earth Graphite Earth Graphite - Boron
carbide Volume ratio of graphite powder and binder 1: 5.5 1: 5.5 1: 5.5 - - Strength reinforcement paste treatment Pressure (MPa) 13 13 13 13 - Curing step Temperature (℃) 100 - 100 100 - Carbonization stage Temperature (℃) 1300 900 - 900 1200 Bending strength (MPa) 38.3 11.3 3.8 2.4 18 Specific resistance (μΩm) 11.27 12.07 11.86 19.73 - Durability rating × × ○ ○ ○

As can be seen in Table 1 to Table 5,

Examples 1, 3 and 5 satisfying all kinds of graphite powder, weight ratio of phenolic resin and organic solvent, volume ratio of graphite powder and binder, pressurization pressure, curing process and carbonization process conditions, etc. , Example 6, Examples 8 to 10, Example 13, Example 14, Example 19, and Example 20, in which any one of them is missing, Example 2, Example 7, Example 11, Example 12, Compared with Examples 15 to 18, Examples 21 and Comparative Examples 1 to 4, the bending strength was excellent, the resistivity was low, the electrical properties were excellent, and the durability of the bulk graphite composite was excellent.

Specifically, Example 1 and Example 3, which satisfies the weight ratio of the phenolic resin and the organic solvent according to the present invention was superior in durability compared to Example 2, which does not satisfy this, excellent bending strength compared to Example 4 It was.

In addition, Example 1, Example 5 and Example 6, which satisfies the type of graphite powder according to the present invention has excellent bending strength, low specific resistance, excellent electrical characteristics, and excellent durability of the bulk graphite composite.

In addition, Example 1, Examples 8 to 10, which satisfies the volume ratio of the graphite powder and the binder according to the present invention, the electrical resistance was excellent because of the low specific resistance compared to Example 7, which does not satisfy this, in Example 11 Compared with the bending strength was excellent.

In addition, Example 1, Example 13 and Example 14, which satisfies the pressure range of the pressing step according to the present invention, the bending strength was excellent compared to Example 12, which does not satisfy this, excellent durability compared to Example 15 It was.

In addition, Example 1, which satisfies the range of the curing temperature according to the present invention, was superior in durability compared to Example 16, which does not satisfy this, and was superior in bending strength and durability in comparison with Example 17.

In addition, Example 1, Example 19 and Example 20, which satisfies the range of carbonization temperature according to the present invention, the bending strength was superior to Example 18, which does not satisfy this, it was excellent in durability compared to Example 21 .

In addition, Example 1, which performed the curing process according to the present invention, was superior in bending strength and durability compared to Comparative Example 1, which did not perform the curing process.

In addition, Example 1, which performed the carbonization process according to the present invention, was significantly superior in bending strength as compared to Comparative Example 2, which did not perform the carbonization process.

In addition, Example 1 using the strength reinforcing paste containing the graphite powder according to the present invention was significantly superior in bending strength and low in electrical resistance compared to Comparative Example 3 in which the graphite powder was not used, and thus had excellent electrical characteristics.

In addition, Example 1 using the strength reinforcing paste containing the graphite powder according to the present invention has excellent bending strength and low electrical resistance as compared with Comparative Example 4 using ceramics, and was excellent in electrical characteristics.

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments set forth herein, and those skilled in the art who understand the spirit of the present invention may add components within the scope of the same idea. Other embodiments may be easily proposed by changing, deleting, adding, and the like, but this will also fall within the spirit of the present invention.

Claims (12)

(1) preparing a binder comprising a phenolic resin and an organic solvent;
(2) preparing a strength reinforcing paste by stirring the graphite powder and the binder in a volume ratio of 1: 0.8 to 10 for 3 to 13 hours;
(3) applying the strength reinforcing paste to the bulk graphite and pressing it at a pressure of 3 to 23 MPa to treat the strength reinforcing paste to the bulk graphite;
(4) curing the strength reinforcing paste treated in bulk graphite at 70 to 120 ° C. for 0.5 to 2.5 hours; And
(5) bonding the bulk graphite and the cured strength reinforcing paste through a carbonization process; bulk graphite composite manufacturing method comprising a. The method of claim 1,
The binder is a bulk graphite composite production method comprising a phenolic resin and an organic solvent in a weight ratio of 1: 0.1 to 10. The method of claim 1,
The graphite powder of step (2) is a bulk graphite composite manufacturing method of at least one powder selected from the group consisting of earth graphite, artificial graphite and natural graphite. delete delete delete The method of claim 1,
The step (5) is the bulk graphite composite manufacturing method performed at 600 ~ 1200 ℃ for 0.5 ~ 3.5 hours. The method of claim 1,
The phenolic resin is a powdery bulk graphite composite manufacturing method. The method of claim 1,
The organic solvent is a bulk graphite composite manufacturing method comprising one or more selected from the group consisting of ethanol, methanol, acetone, formaldehyde and hexamethylenetetramine. It is prepared by the manufacturing method according to any one of claims 1 to 3, 7 to 9,
Bulk graphite composite having a bending strength of 6 to 46 MPa and a specific resistance of 9 to 14 μΩ · m measured by the following Measuring Method 1:
[Measurement method 1]
The bulk graphite composite was molded to a thickness of 1 cm, and the bending strength was measured by a three-point bending test method at a speed of 1 mm / min using a universal testing machine (i-50, EXEL LAB). delete delete

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