KR20120043294A - Machinable ceramic composite material with black color and manufacturing method of the same - Google Patents

Abstract

PURPOSE: A machinable black ceramic complex and a manufacturing method thereof are provided to enhance crystal state by using a hot pressing process. CONSTITUTION: A machinable black ceramic complex comprises zirconia(ZrO2), boron nitride(BN), yttrium oxide(Y2O3), and alumina(Al2O3). The zirconia(ZrO2) and boron nitride(BN) are contained 78-96 weight%. The yttrium oxide(Y2O3) is contained 3-12 weight% and the alumina (Al2O3) is contained 1-10 weight%. The machinable black ceramic complex has a flexural strength of 120-160MPa and a thermal expansion coefficient of 6.0-9.0×10^-6/degree Celsius. A manufacturing method of the machinable black ceramic composite comprises next steps: mixing material powders; charging compound powder in a mold of a furnace; sintering and hot pressing the compound powder; obtaining machinable ceramic composite by cooling the furnace; placing the machinable ceramic composite and carbon group powder in a crucible; charging the crucible into the furnace; exhausting impurity gas within the furnace; processing a thermal process to make the ceramic black; and obtaining the machinable black ceramic composite by cooling the furnace.

Description

Machinable ceramic composite material with black color and manufacturing method of the same

The present invention relates to a machinable ceramic composite and a method of manufacturing the same, and more particularly, a machinable black ceramic composite having excellent crystal state, excellent mechanical properties, very dense spacing between particles, excellent machinability, and low brightness. And to a method for producing the same.

In general, ceramics have excellent properties of withstanding high temperatures and exhibit good mechanical properties and insulation. Due to this property of ceramics, it is widely used as a component of a semiconductor manufacturing apparatus. However, most ceramics have poor mechanical workability due to their brittle characteristics.

In the case of crystallized glass as an example for improving the mechanical workability, cleavable ceramic components such as boron nitride (BN) are dispersed in the glass matrix to improve the mechanical workability. Such a ceramic having excellent machinability is called a machinable ceramic.

Machinable ceramics are required to have good machinability, good insulating properties, and high precision micromachining.

Korean Patent Publication No. 10-0616001 discloses a machinable ceramic. In a machinable ceramic including a main constituent and a sintering aid, the main component is boron nitride 30 to 30. 59.95 mass%, zirconia 40 to 69.95 mass%, silicon nitride 0 to 20 mass% and at least one coloring additive 0.05 to 2.5 mass%, said ceramics present machinable ceramics with a black color.

An object of the present invention is to provide a machinable black ceramic composite having excellent crystal state, excellent mechanical properties, very dense spacing between particles, excellent machinability, and low brightness, and a method of manufacturing the same.

The present invention includes zirconia (ZrO ₂ ), boron nitride (BN), yttrium oxide (Y ₂ O ₃ ) and alumina (Al ₂ O ₃ ), wherein the zirconia (ZrO ₂ ) and the boron nitride (BN) 78 to 96% by weight, the yttrium oxide (Y ₂ O ₃ ) is contained 3 to 12% by weight, the alumina (Al ₂ O ₃ ) is contained 1 to 10% by weight, the bending strength is 100 ~ 160 MPa The thermal expansion coefficient is in the range of 6.0? 9.0 × 10 ⁻⁶ / ° C. and provides a machinable black ceramic composite having a whiteness in the range of 30-50.

Preferably, the zirconia (ZrO ₂ ) and the boron nitride (BN) form a weight ratio of 1: 0.8 to 1: 1.2.

In addition, the present invention is (a) 78 to 96% by weight of zirconia (ZrO ₂ ) powder and boron nitride (BN) powder, 3 to 12% by weight of yttrium oxide (Y ₂ O ₃ ) powder and alumina (Al ₂ O ₃ ) Mixing 1 to 10% by weight of powder, and (b) a mixed powder of zirconia (ZrO ₂ ) powder, boron nitride (BN) powder, yttrium oxide (Y ₂ O ₃ ) powder and alumina (Al ₂ O ₃ ) powder Charging to a mold provided in the furnace, and (c) raising the temperature of the furnace to a target sintering temperature lower than the melting temperature of zirconia (ZrO ₂ ) and boron nitride (BN), and mixing at the sintering temperature. Sintering under pressure to powder, (d) cooling the furnace to obtain a machinable ceramic composite, (e) containing the machinable ceramic composite and carbonaceous powder for blackening in a crucible, and Charging the furnace to the furnace, and (f) operating the pump to remove impurities present in the furnace. Evacuating, (g) raising the temperature of the furnace to a target heat treatment temperature, maintaining the heat treatment temperature to perform heat treatment for blackening, and (h) cooling the furnace to cool the machinable black ceramic composite. It provides a method for producing a machinable black ceramic composite comprising the step of obtaining.

In the step (a), the zirconia (ZrO ₂ ) powder and The boron nitride (BN) powder is preferably mixed in a weight ratio of 1: 0.8-1: 1.2.

The heat treatment temperature is in the range of 1600-1800 ° C., and the pressure in the furnace during the heat treatment is preferably kept constant in the range of 1 × 10 ^{−1 −1} × 10 ⁻⁵ Torr.

The carbon-based powder uses at least one powder selected from carbon black, graphite and carbon nanotubes, and the machinable ceramic composite The carbon-based powder is preferably contained in the crucible in a ratio of 1: 0.5 to 1:10 by volume.

As the crucible, it is preferable to use a crucible made of a graphite material composed of carbon (C) components.

The sintering temperature is in the range of 1550 ~ 1800 ℃, the sintering is preferably performed for 10 minutes ~ 6 hours in consideration of the microstructure and mechanical properties of the sintered body.

The pressure applied to the mixed powder is in the range of 20 to 60 MPa, and it is preferable to perform up and down bidirectional compression in the upper and lower portions of the mold.

The mold uses a mold made of graphite material, the sintering is performed in a nitrogen (N ₂ ) gas atmosphere, the nitrogen gas is preferably supplied at a flow rate of 200 ~ 2000sccm range.

The mixing uses a wet ball milling process, the wet ball milling process uses zirconia or alumina balls, the wet ball milling port uses a port made of Teflon material, and the ball size is 1 mm to 30 mm. It is preferable to set the range, the rotational speed of the ball mill is set in the range of 50 to 500 rpm, and the ball milling is performed for 1 to 48 hours.

The machinable black ceramic composite produced by the present invention is a sintered compact having a density of about 4.0 to 5.0 g / cm 3, very dense spacing between particles and almost no pores, and excellent in crystalline state.

In addition, the machinable black ceramic composite prepared according to the preferred embodiment of the present invention has a bending strength of about 100 to 160 MPa and a thermal expansion coefficient of about 6.0 to 9.0 × 10 ⁻⁶ / ° C., which is very excellent in mechanical properties. And the mechanical workability is very excellent.

In addition, the machinable black ceramic composite prepared according to the preferred embodiment of the present invention has a low whiteness of about 30-50 degrees.

1 is a graph measuring the density of a machinable ceramic composite prepared according to Example 1. FIG.
Figure 2 is a graph measuring the flexural strength of the machinable ceramic composite prepared according to Example 1.
3 is a graph measuring a thermal coefficient of the machinable ceramic composite prepared according to Example 1. FIG.
FIG. 4 is a photograph showing processing holes having a diameter of 60 μm in order to confirm mechanical machinability of the machinable ceramic composite prepared according to Example 1. FIG.
5 is a Scanning Electron Microscope (SEM) photograph showing the machinable black ceramic composite prepared according to Example 2. FIG.
Referring to FIG. 5, the machinable black ceramic composite prepared according to Example 2 can be seen that boron nitride (BN) and zirconia (ZrO ₂ ) are uniformly dispersed as a main component.
Figure 6 is a graph measuring the density of the machinable black ceramic composite prepared according to Example 2.
7 is a graph measuring the flexural strength of the machinable black ceramic composite prepared according to Example 2. FIG.
FIG. 8 is a graph measuring a thermal coefficient of a machinable black ceramic composite prepared according to Example 2. FIG.
9 is a graph showing the whiteness of the machinable ceramic composite prepared according to Example 1 and the machinable black ceramic composite prepared according to Example 2. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. It doesn't happen.

The machinable black ceramic composite according to the preferred embodiment of the present invention includes zirconia (ZrO ₂ ), boron nitride (BN), yttrium oxide (Y ₂ O ₃ ) and alumina (Al ₂ O ₃ ), and zirconia (ZrO ₂ ) And boron nitride (BN) are contained 78 to 96% by weight based on 100% by weight of the machinable black ceramic composite, yttrium oxide (Y ₂ O ₃ ) is 3 to 12% by weight relative to 100% by weight of the machinable black ceramic composite. Alumina (Al ₂ O ₃ ) is contained in an amount of 1 to 10% by weight based on 100% by weight of the machinable black ceramic composite. The zirconia (ZrO ₂ ) and the boron nitride (BN) is contained 78 ~ 96% by weight relative to 100% by weight of the machinable black ceramic composite, the weight ratio (ZrO ₂ : BN) of zirconia (ZrO ₂ ) and boron nitride (BN). ) Is preferably in the range from 1: 0.8 to 1: 1.2.

The machinable black ceramic composite of the present invention has a density of about 4.0 to 5.0 g / cm 3, a bending strength of about 120 to 160 MPa, and a coefficient of thermal expansion of about 6.0 to 9.0 × 10 ⁻⁶ / ° C., which has mechanical properties. Excellent and very good mechanical workability.

In addition, the machinable black ceramic composite of the present invention has a low whiteness of about 30-50 degrees.

Hereinafter, a method of manufacturing a machinable black ceramic composite according to a preferred embodiment of the present invention. In the following description, the machinable ceramic composite material refers to a material obtained in a step before the sintering process is performed and the blackening process, and the machinable black ceramic composite material is obtained by performing a blackening process after the sintering process. We use by doing.

Zirconia (ZrO ₂ ) powder and boron nitride (BN) powder 78 to 96 wt%, yttrium oxide (Y ₂ O ₃ ) powder 3 to 12 wt% and alumina (Al ₂ O ₃ ) powder to produce machinable ceramic composites Each raw material is weighed to contain 1 to 10% by weight. At this time, the weight ratio (ZrO ₂ : BN) of zirconia (ZrO ₂ ) and boron nitride (BN) is in the range of 1: 0.8 to 1: 1.2.

Zirconia (ZrO ₂ ) and boron nitride (BN) are the bases of machinable ceramic composites.

Boron nitride (BN) is difficult to sinter due to poor sintering. Therefore, yttrium oxide (Y ₂ O ₃ ) powder and alumina (Al ₂ O ₃ ) powder are mixed to improve sintering, lower sintering temperature and improve mechanical properties. Add.

Mix the above raw materials. The mixing may use a ball milling process. The ball milling process will be described in detail with a ball milling machine comprising zirconia (ZrO ₂ ) powder, boron nitride (BN) powder, yttrium oxide (Y ₂ O ₃ ) powder, and alumina (Al ₂ O ₃ ) powder. ) Is mixed with a solvent such as water and alcohol, and rotated at a constant speed using a ball mill to mechanically uniformly mix the raw powders. The port used for ball milling can use a Teflon port, and the use of Teflon port can eliminate the contamination or compositional unevenness caused by wear in the ball milling process. This is because the Teflon component contained from the Teflon pot in the ball milling process can be burned out in a subsequent sintering process. It is preferable to use zirconia or alumina balls made of the same material as zirconia (ZrO ₂ ) powder or alumina (Al ₂ O ₃ ) powder included in the raw material in terms of not generating impurities, and the balls are all the same size. You can use two or more sizes of balls together. Mix by adjusting the size of the ball, milling time, revolution per minute of the ball mill, etc. For example, the size of the ball is set in the range of about 1 mm to 30 mm, the rotation speed of the ball mill is set in the range of about 50 to 500 rpm, and ball milling is performed for 1 to 48 hours. By ball milling the raw materials are evenly mixed.

Dry the mixed raw materials. The drying is preferably carried out for 30 minutes to 24 hours at a temperature of 60 ~ 120 ℃.

Since the dried raw materials may be agglomerated, they may be pulverized using a device such as alumina induction, and the pulverized powder may be sieved using a sieve of a predetermined mesh (eg, 325 mesh).

The mixed powder mixed with the raw materials is sintered by hot pressing.

The hot pressing sintering method is a method of sintering while applying a high pressure, and sintering is possible at a lower temperature than atmospheric pressure sintering, and the sintering time is also shortened. Boron nitride (BN) is difficult to sinter at normal pressure because it is not sintered well, and in order to use atmospheric sintering, there is a disadvantage in that the temperature is raised to near the melting point of boron nitride (BN) and sintered at a high temperature. In addition, the machinable ceramic composite sintered by atmospheric sintering has a problem of low relative density and inferior mechanical properties as compared with the hot pressing sintering method. In addition, in the case of using atmospheric sintering, since the temperature must be raised to near the melting point of boron nitride (BN), energy consumption is high and thermal stress is applied too much to the sintered specimen.

Therefore, in the present invention, by using the hot pressing sintering method, a high density machinable ceramic composite in which pores are hardly formed by making the spacing between particles very dense can be produced.

Hereinafter, a method of forming a high density machinable ceramic composite using the hot pressing sintering method will be described.

First, a mixed powder of zirconia (ZrO ₂ ), boron nitride (BN), yttrium oxide (Y ₂ O ₃ ) and alumina (Al ₂ O ₃ ) is prepared. In particular, zirconia (ZrO ₂₎ particle size of the powder and a boron nitride (BN) particle size of the powder is machinable Assignable density of the ceramic composite, may have an impact such as mechanical properties, in consideration of this, zirconia (ZrO ₂₎ powder and a boron nitride (BN) powder Select. Preferably, it is preferable to use spherical powder having a particle diameter of 1 µm or less in consideration that the machinable ceramic composite is used for precision microfabrication or the like.

A mixed powder of zirconia (ZrO ₂ ), boron nitride (BN), yttrium oxide (Y ₂ O ₃ ) and alumina (Al ₂ O ₃ ) is charged to a mold provided in a furnace. The mold may be provided in a cylinder or prismatic shape, and after charging the mixed powder in the mold, it can be formed into a desired shape by performing the vertical and bidirectional compression or one-way compression in the upper and lower molds. In this case, the pressure applied to the mixed powder (pressure compressed by the mold) is preferably about 20 to 60 MPa. When the pressurization pressure is too small, there are many voids between the mixed powder particles, so that the desired high density machinable ceramic composite is If it is difficult to obtain and the pressurization pressure is too large, no further effect can be expected, and the manufacturing cost of the equipment may increase due to the addition of a mold, a hydraulic device, etc. according to the high pressure. The mold is preferably made of a graphite (graphite) material having a high hardness and a high melting point.

In order to remove and purge the impurity gas present in the furnace, the rotary pump is operated to evacuate until it is in a vacuum state (for example, about 1 × 10 ¹ −1 × 10 ⁻³ Torr). At this time, when the furnace is heated by supplying power to the heating means surrounding the furnace, the impurity gas remaining in the furnace can be efficiently exhausted.

The furnace temperature is raised to a target sintering temperature (eg, 1550-1800 ° C.) which is lower than the melting temperature of zirconia (ZrO ₂ ) and boron nitride (BN). At this time, nitrogen (N ₂ ) gas is supplied to stabilize the atmosphere during sintering, and the gas atmosphere of the furnace is sufficiently supplied with a nitrogen gas atmosphere. For example, it is preferable to supply nitrogen gas at a flow rate of about 200 to 2000 sccm. .

The sintering temperature is preferably about 1550 ~ 1800 ℃ in consideration of the diffusion of particles, the necking (necking) between the particles, etc. If the sintering temperature is too high, mechanical properties may decrease due to excessive growth of particles, If the sintering temperature is too low, it is preferable to sinter at the sintering temperature in the above range because the characteristics of the sintered body may be poor due to incomplete sintering. At this time, the temperature increase rate of the furnace is preferably about 1 ~ 50 ℃ / min, but if the temperature rising rate of the furnace is too slow, productivity takes a long time, if the temperature rising rate of the furnace is too fast, the sintered body by a sudden temperature rise It is preferable to raise the temperature of the furnace at a temperature rising rate in the above range because it may adversely affect the characteristics of the.

When the furnace temperature rises to the target sintering temperature, the furnace is kept sintered for a predetermined time (for example, 10 minutes to 6 hours). According to the sintering temperature, there is a difference in the microstructure of the sintered body, etc., since the surface diffusion is dominant when the sintering temperature is low, while the lattice diffusion and grain boundary diffusion are advanced when the sintering temperature is high. The sintering time is preferably about 10 minutes to 6 hours when using a furnace for general heat treatment, but when the sintering time is too long, it is not only economical, but also difficult to expect further sintering effect. When the size of the sintered body becomes large and the sintering time is small, the characteristics of the sintered body may be poor due to incomplete sintering. It is preferable that the pressure applied to the mixed powder during sintering is about 20 to 60 MPa. If the pressurization pressure is too small, it is difficult to obtain the desired high density machinable ceramic composite, and if the pressurization pressure is too large, the sintered body after the sintering process is cracked. Etc. may occur.

After the sintering process, the furnace temperature is lowered to unload the machinable ceramic composite. The furnace cooling may be allowed to cool down in a natural state by turning off the furnace power source, or to set a temperature drop rate (eg, 10 ° C./min) arbitrarily. The pressure inside the furnace is preferably kept constant while the furnace temperature is lowered.

The machinable ceramic composite prepared according to the preferred embodiment of the present invention is a sintered compact having a density of about 4.0 to 5.0 g / cm 3, very dense spacing between particles, and almost no pores, and excellent in crystalline state.

In addition, the machinable ceramic composite prepared according to the preferred embodiment of the present invention has a bending strength of about 120 to 160 MPa, a thermal expansion coefficient of about 6.0 to 9.0 × 10 ⁻⁶ / ° C., and has excellent mechanical properties. Mechanical workability is also very good.

In order to obtain a machinable black ceramic composite by blackening the machinable ceramic composite prepared as described above, the following blackening process is performed.

A machinable ceramic composite and carbonaceous powder for blackening are placed in a crucible, and the crucible is charged into a furnace. The machinable ceramic composite and the carbon-based powder are contained in a crucible in a volume ratio (eg, machinable ceramic composite: carbon-based powder = 1: 0.5 to 1:10) at a predetermined ratio. The carbon-based powder is a powder made of a carbon-based material such as carbon black, graphite, and carbon nanotubes. The crucible is preferably made of a graphite material having the same material as carbon (C) constituting the carbon-based powder, and having a high hardness and a high melting point. This is because it may act as an impurity in.

A rotary pump (not shown) is operated to remove the impurity gas present in the furnace and to evacuate until it reaches a vacuum state (for example, about 1 × 10 ^{−1 −1} × 10 ⁻⁵ Torr). At this time, when the furnace is heated by supplying power to a heating means (not shown) surrounding the circumference of the furnace, the impurity gas remaining in the furnace can be efficiently exhausted.

The temperature of the furnace is raised to a target heat treatment temperature (eg 1600-1800 ° C.). At this time, it is preferable to maintain the vacuum state of the furnace as it is, and the temperature increase rate of the furnace is preferably about 1 ~ 50 ℃ / min, if the temperature increase rate of the furnace is too slow, it takes a long time to reduce productivity and the furnace If the temperature increase rate is too fast, it is preferable to raise the temperature of the furnace at the temperature increase rate in the above range because the rapid temperature rise may adversely affect the properties of the machinable black ceramic composite.

When the temperature of the furnace rises to the target heat treatment temperature, a constant time (for example, 10 minutes-6 hours) is maintained. The heat treatment causes blackening of the machinable ceramic composite. In this case, the carbon-based powder serves to make the machinable ceramic composite material black. The heat treatment time is preferably 10 minutes to 6 hours when the furnace for general heat treatment is used. However, when the heat treatment time is too long, it is not only economical, but also expects more blackening effect. If the heat treatment time is difficult and the heat treatment time is small, it may be difficult to obtain a machinable black ceramic composite having a desired brightness due to incomplete blackening. Even during the heat treatment, the pressure inside the furnace is preferably kept constant at about 1 × 10 ^{−1 −1} × 10 ⁻⁵ Torr.

After performing a heat treatment process for blackening, the furnace temperature is lowered to unload the machinable black ceramic composite. The furnace cooling may be allowed to cool down in a natural state by turning off the furnace power source, or to set a temperature drop rate (eg, 10 ° C./min) arbitrarily. The pressure inside the furnace is preferably kept constant while the furnace temperature is lowered.

The machinable black ceramic composite prepared in accordance with the preferred embodiment of the present invention has a density of about 4.0 to 5.0 g / cm 3, and is a sintered compact having very dense spacing between particles and hardly forming pores, and having excellent crystal state.

In addition, the machinable black ceramic composite prepared according to the preferred embodiment of the present invention has a bending strength of about 100 to 160 MPa and a coefficient of thermal expansion of about 6.0 to 9.0 × 10 ⁻⁶ / ° C., and has excellent mechanical properties. The mechanical workability is also very good.

In addition, the machinable black ceramic composite prepared according to the preferred embodiment of the present invention has a black color with a degree of 30-50.

Hereinafter, the embodiments of the present invention will be described in more detail, and the present invention is not limited to the following examples.

≪ Example 1 >

Zirconia (ZrO ₂ ) powder The boron nitride (BN) powder is weighed in a weight ratio of 1: 1, and a mixture of the weighed zirconia (ZrO ₂ ) and boron nitride (BN) powders, yttrium oxide (Y ₂ O ₃ ) powder and alumina (Al ₂ O ₃ ) The powders were mixed, zirconia (ZrO ₂ ) and boron nitride (BN) powders contained 87% by weight, yttria (Y ₂ O ₃ ) powders contained 8% by weight and alumina (Al ₂ O ₃ ) powder 5 wt% of silver was contained. The mixing was performed using a wet ball milling process. Specifically, ethanol was wet mixed for 12 hours at a speed of 100 rpm in a Teflon pot using a 5 mm zirconia ball as a solvent.

After mixing, the slurry was extracted and dried in a drier at 80 ° C. for 24 hours, and then the dried body was ground using alumina induction. The pulverized mixed powder was sieved using a 325 mesh sieve.

The mixed powder thus obtained was put into a cylindrical mold provided in a furnace, and molded into a molded body by applying upward and downward bidirectional pressure at the top and bottom of the mold. At this time, the pressure compressed by the mold was about 40 MPa. The mold used a mold made of graphite (graphite).

The rotary pump was operated to purge to remove the impurity gas present in the furnace. The electric power was supplied to the heating means surrounding the furnace, and the furnace was heated to raise the sintering temperature to 1650 ° C. At this time, the temperature increase rate of the furnace was about 5 ° C / min.

The temperature of the furnace was raised to 1650 ° C. and then sintered for 2 hours. Even during sintering, the pressure applied to the mixed powder was kept constant at about 40 MPa.

After the sintering process, the furnace temperature was lowered to unload the machinable ceramic composite. The furnace cooling shuts down the furnace power, allowing the furnace to cool in its natural state.

Figure 1 is a graph measuring the density of the machinable ceramic composite prepared according to Example 1, it was shown by measuring the density (density) for 10 samples.

Referring to FIG. 1, the machinable ceramic composite prepared according to Example 1 was confirmed to have a density in the range of 4.15 to 4.18 g / cm 3.

FIG. 2 is a graph measuring flexural strength of a machinable ceramic composite prepared according to Example 1, and is shown by measuring bending strength of 10 samples.

Referring to FIG. 2, the machinable ceramic composite prepared according to Example 1 was found to have a bending strength in the range of 130 to 150 MPa.

FIG. 3 is a graph of measuring thermal coefficients of machinable ceramic composites prepared according to Example 1, and the coefficients of thermal expansion of ten samples were measured.

Referring to Figure 3, the machinable ceramic composite prepared according to Example 1 was confirmed to have a thermal expansion coefficient of 7.0 ~ 7.48 × 10 ^-6 ℃ range.

FIG. 4 is a photograph showing processing holes having a diameter of 60 μm in order to confirm mechanical machinability of the machinable ceramic composite prepared according to Example 1. FIG.

Referring to FIG. 4, the machinable ceramic composite prepared according to Example 1 hardly generated cracks around holes during machining, and was able to process fine holes as intended because of excellent mechanical workability.

<Example 2>

The machinable ceramic composite prepared according to Example 1 and graphite powder, which is a carbon-based powder for blackening, were placed in a crucible, and the crucible was charged in a furnace. The machinable ceramic composite and the graphite powder were contained in a crucible in a volume ratio of 1: 1, and the graphite powder was used as a powder having an average particle diameter of 0.5 μm. The crucible was a crucible made of graphite material.

In order to remove the impurity gas present in the furnace and create a vacuum, a rotary pump (not shown) was operated to obtain a vacuum of about 5 × 10 ⁻² Torr.

The electric power was supplied to the heating means (not shown) surrounding the circumference of the furnace, and the furnace was heated to raise the heat treatment temperature to 1700 ° C. At this time, the vacuum state of the furnace was maintained as it is about 5 × 10 ^-2 Torr, the temperature increase rate of the furnace was about 5 ℃ / min.

After raising the temperature of the furnace to 1700 ℃, it was maintained for 2 hours to perform a heat treatment for blackening. During the heat treatment, the pressure inside the furnace was kept constant at about 5 × 10 ⁻² Torr.

After the heat treatment process, the furnace temperature was lowered to unload the machinable black ceramic composite. The furnace cooling shuts down the furnace power, allowing the furnace to cool in its natural state.

5 is a Scanning Electron Microscope (SEM) photograph showing the machinable black ceramic composite prepared according to Example 2. FIG.

Referring to FIG. 5, the machinable black ceramic composite prepared according to Example 2 can be seen that boron nitride (BN) and zirconia (ZrO ₂ ) are uniformly dispersed as a main component.

6 is a graph measuring the density of the machinable black ceramic composite prepared according to Example 2, and shows the density (density) of 10 samples.

Referring to FIG. 6, the machinable black ceramic composite prepared according to Example 2 was confirmed to have a density in the range of 4.15 to 4.18 g / cm 3.

7 is a graph measuring the flexural strength of the machinable black ceramic composite prepared according to Example 2, and the bending strength was measured for 10 samples.

Referring to FIG. 7, the machinable black ceramic composite prepared according to Example 2 was found to have a bending strength in the range of 110 to 140 MPa.

FIG. 8 is a graph illustrating a thermal coefficient of thermal expansion of a machinable black ceramic composite prepared according to Example 2, and the coefficient of thermal expansion of ten samples was measured.

Referring to FIG. 8, the machinable black ceramic composite prepared according to Example 2 was confirmed to have a thermal expansion coefficient in the range of 7.0 to 7.48 × 10 ⁻⁶ ° C.

9 is a graph showing the whiteness of the machinable ceramic composite prepared according to Example 1 and the machinable black ceramic composite prepared according to Example 2. FIG. In Figure 9, (a) is the whiteness of the white specimen for relative comparison, (b) is the whiteness of the machinable ceramic composite prepared according to Example 1, (c) is machinable prepared according to Example 2 Whiteness of the black ceramic composite. Whiteness was measured using a colormeter, and the whiteness is expressed as 100 at full white and 0 at full black.

Referring to FIG. 9, in the case of a white specimen for comparative comparison, the whiteness is about 85, and the machinable ceramic composite prepared according to Example 1 has a whiteness of about 70, and the machinable black ceramic composite prepared according to Example 2 The whiteness was about 40 degrees. From this, it was confirmed that the machinable black ceramic composite prepared according to Example 2 by the blackening process was lower in brightness than the machinable ceramic composite prepared according to Example 1.

As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various deformation | transformation by a person of ordinary skill in the art within the scope of the technical idea of this invention is carried out. This is possible.

Claims (11)

Zirconia (ZrO ₂ ), boron nitride (BN), yttrium oxide (Y ₂ O ₃ ) and alumina (Al ₂ O ₃ ), the zirconia (ZrO ₂ ) and the boron nitride (BN) is 78 to 96 weight %, The yttrium oxide (Y ₂ O ₃ ) is contained 3 to 12% by weight, the alumina (Al ₂ O ₃ ) is contained 1 to 10% by weight, the bending strength is about 100 ~ 160 MPa, thermal expansion A machinable black ceramic composite, wherein the modulus is in the range of 6.0 to 9.0 × 10 ⁻⁶ / ° C., and the degree of whiteness is in the range of 30 to 50.
The machinable black ceramic composite of claim 1, wherein the zirconia (ZrO ₂ ) and the boron nitride (BN) form a weight ratio of 1: 0.8 to 1: 1.2.
(a) 78 to 96% by weight of zirconia (ZrO ₂ ) and boron nitride (BN) powder, 3 to 12% by weight of yttrium (Y ₂ O ₃ ) powder and 1 to 10% by weight of alumina (Al ₂ O ₃ ) powder Mixing;
(b) charging a mixed powder of zirconia (ZrO ₂ ) powder, boron nitride (BN) powder, yttrium oxide (Y ₂ O ₃ ) powder and alumina (Al ₂ O ₃ ) powder into a mold provided in the furnace;
(c) raising the temperature of the furnace to a target sintering temperature lower than the melting temperature of zirconia (ZrO ₂ ) and boron nitride (BN), and sintering while applying pressure to the mixed powder at the sintering temperature;
(d) cooling the furnace to obtain a machinable ceramic composite;
(e) placing the machinable ceramic composite and carbonaceous powder for blackening in a crucible and charging the crucible into a furnace;
(f) operating the pump to exhaust the impurity gas present in the furnace;
(g) raising the temperature of the furnace to a target heat treatment temperature and maintaining the heat treatment temperature to perform heat treatment for blackening; And
(h) cooling the furnace to obtain a machinable black ceramic composite.
The method of claim 3, wherein in step (a),
Zirconia (ZrO ₂ ) powder and The boron nitride (BN) powder is a method of manufacturing a machinable black ceramic composite, characterized in that the mixing in a weight ratio of 1: 0.8 ~ 1: 1.2.
4. The machine according to claim 3, wherein the heat treatment temperature is in the range of 1600-1800 ° C, and the pressure in the furnace is kept constant in the range of 1x10 ^-1 -1x10 ^-5 Torr during the heat treatment. Method for producing a nibble black ceramic composite.
The method of claim 3, wherein the carbon-based powder is used at least one powder selected from carbon black, graphite and carbon nanotubes, and the machinable ceramic composite The carbon-based powder is a method of manufacturing a machinable black ceramic composite, characterized in that the crucible is contained in the crucible in a ratio of 1: 0.5 to 1:10.
The method of claim 3, wherein the crucible is a crucible made of a graphite material including carbon (C).
The method of claim 3, wherein the sintering temperature is in a range of 1550 ° C. to 1800 ° C., and the sintering is performed for 10 minutes to 6 hours in consideration of the microstructure and mechanical properties of the sintered body. .
The method of claim 3, wherein the pressure applied to the mixed powder is in a range of 20 to 60 MPa, and the bidirectional compression is performed in the upper and lower portions of the mold.
The mold of claim 3, wherein the mold is formed of a graphite material, and the sintering is performed in a nitrogen (N ₂ ) gas atmosphere, and the nitrogen gas is supplied at a flow rate in the range of 200 to 2000 sccm. Method for producing a black ceramic composite.
The method of claim 3, wherein the mixing uses a wet ball milling process,
The wet ball milling process uses a zirconia or alumina ball, the port in which the wet ball mill is made using a port made of Teflon material, the size of the ball is set in the range of 1mm ~ 30mm, the rotation speed of the ball mill It is set in the range of 50 ~ 500rpm, ball milling method for producing a machinable black ceramic composite, characterized in that performed for 1 to 48 hours.

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