KR102595822B1 - High-density alumina manufacturing method for plasma resistance using HIP - Google Patents

Abstract

The present invention relates to a method of manufacturing high-density alumina for anti-plasma using HIP, and more specifically, the steps of adding alumina powder and zirconia balls having a certain average particle size into a milling container; Adding distilled water to the milling vessel to slurry the alumina powder and then performing primary ball milling; After primary ball milling, adding a binder and a plasticizer to the slurry and performing secondary ball milling; Drying the secondary ball milled slurry to form spherical alumina granule powder with a certain particle size; Sifting the formed alumina granule powder to remove aggregates; Densifying the alumina granule powder from which aggregates have been removed under a certain pressure to produce an alumina molded body; Sintering the produced alumina molded body under certain conditions to produce a sintered body; and removing pores contained in the generated alumina sintered body using a hot isostatic pressing method.

Description

High-density alumina manufacturing method for plasma resistance using HIP}

The present invention relates to a method of manufacturing high-density alumina for plasma-resistant using HIP, and more specifically, high-density alumina for plasma-resistant which is translucent and has a relative density of 99.6% or more using hot isostatic pressing (HIP). It is about manufacturing method.

Alumina (Al ₂ O ₃ ) is chemically stable, has a high melting point (2,050°C), and is widely used in mechanical parts and fixtures such as fiber seals, pump seals, and semiconductor fixtures due to its wear resistance, corrosion resistance, and heat resistance. For alumina ceramics products that require high strength, wear resistance, and corrosion resistance, the fewer pores, that is, the higher the density, the better the wear resistance and corrosion resistance. The stronger the product, the more fine and uniformly sized crystal grains it has or the smaller the size of defects such as pores and cracks. is high.

On the other hand, it is well known that the method of increasing fracture toughness by adding 20% to 30% by volume of ZrO ₂ to alumina to cause stress induced phase transformation ignition phenomenon is well known, but this method increases the hardness when a large amount of ZrO ₂ , which has relatively low hardness, is added. There is a disadvantage that the wear resistance of ceramics may be reduced by significantly reducing the wear resistance.

In addition, these alumina ceramics are manufactured by dry or wet molding alumina powder and sintering at a high temperature of usually 1,600°C or higher.

Meanwhile, in order to obtain crystal grains of uniform size, the method of adding about 0.1% by weight of MgO to alumina raw material powder is a well-known method.

This trace amount of MgO prevents abnormal grain growth when alumina is sintered, resulting in uniformly sized grains, and also allows alumina to be produced with relatively small pore sizes.

However, since conventionally produced alumina ceramics are sintered at a high temperature of 1,600°C or higher, the average grain size is 5㎛ or more, and therefore the pore size increases proportionally, and the relative density remains around 98%, so strength and wear resistance are poor. There is a disadvantage in that there is a limit to improving corrosion resistance, etc.

Meanwhile, a high level of corrosion resistance is required in etching, which is an essential process following the introduction of nanotechnology by global semiconductor companies. Alumina materials that meet these requirements have lower manufacturing costs than other ceramic materials and can be used to shape the final product. It has the advantage of being highly competitive due to accumulated experience in the field.

On the other hand, the existing alumina manufactured using granular powder through uniaxial or cold isostatic pressing is sintered in an atmospheric pressure atmosphere of around 1,600°C as described above, and at this time, sintering is not completely densified, leaving residual pores. There is a problem that remains.

When used as an etching gas nozzle, these pores can act as surface defects remaining on the surface after processing, and can affect the gas flow such as flow rate and flow rate, or cause an etching effect by the etching gas, causing contamination (particles) into the chamber. There is a problem that can come into play.

The method for producing high-density alumina for plasma resistance using HIP according to an embodiment of the present invention was created to solve the above-mentioned problems, and is translucent and has a relative density of 99.6% by using hot isostatic pressing (HIP). The purpose is to provide a method for manufacturing high-density alumina for plasma resistance having the above characteristics.

Meanwhile, the objects of the present invention are not limited to the objects mentioned above, and other objects not mentioned can be clearly understood by those skilled in the art from the description below.

In order to achieve the above-mentioned purpose, the method for manufacturing high-density alumina for plasma resistance using HIP according to an embodiment of the present invention includes the steps of adding alumina powder and zirconia balls having a certain average particle size into a milling container, and pouring distilled water into the milling container. After adding the alumina powder into a slurry, performing primary ball milling; after primary ball milling, adding a binder and a plasticizer to the slurry and performing secondary ball milling; drying the secondary ball milled slurry Forming a spherical alumina granule powder having a certain particle size, sieving the formed alumina granule powder to remove aggregates, densifying the alumina granule powder from which the aggregates have been removed under a certain pressure to produce an alumina molded body. , sintering the produced alumina molded body under certain conditions to produce a sintered body, and removing pores contained in the produced alumina sintered body using a hot isostatic pressing method.

Preferably, the alumina powder is an alpha phase with an average particle size of 0.3㎛, and the alumina powder and zirconia balls can be added to the milling container at a ratio of 1:5.

Preferably, in the first ball milling step, 10 to 20 vol% of distilled water is added relative to the total volume of the alumina powder, and ball milling can be performed for 24 to 48 hours.

Preferably, in the secondary ball milling step, 1 wt% of a binder and a plasticizer are added based on the total weight of the alumina powder, and ball milling can be performed for 3 hours.

Preferably, the step of forming the spherical alumina granule powder is dried using a spray dryer, and the particle size of the dried alumina granule powder may be 80 to 100㎛.

Preferably, the step of removing aggregates by sieving the alumina granule powder can be performed using an 80 mesh net with a sieve opening of 170㎛.

Preferably, the step of producing the alumina molded body may be performed through primary densification at a pressure of 100 to 150 kg/cm ² and then secondary densification at a pressure of 1,500 bar.

Preferably, the step of producing the alumina sintered body can be performed by raising the temperature to 1,600°C at 1°C per minute using an electric furnace and then maintaining the temperature at 1,600°C for 5 hours.

Preferably, the step of removing the pores using hot isostatic pressing is performed at 1,400 to 1,500°C, and the alumina may have a relative density of 99.6% or more.

The method for producing high-density alumina for plasma-resistant using HIP according to an embodiment of the present invention is to produce high-density alumina for plasma-resistant which is translucent and has a relative density of 99.6% or more using hot isostatic pressing (HIP). It has excellent effects.

Figure 1 is an overall process diagram of a method for producing high-density alumina for anti-plasma using HIP according to an embodiment of the present invention.
Figure 2 is an image of the alumina sintered body before (a) and after (b) performing hot isostatic pressing (HIP).
Figure 3 is a microstructure image of an alumina sintered body before (a) and after (b) hot isostatic pressing (HIP).
Figure 4 is a comparative image after hole processing of an alumina sintered body before (a) and after (b) hot isostatic pressing (HIP).

The terms used in the present invention are general terms that are currently widely used as much as possible, but in certain cases, there are terms arbitrarily selected by the applicant. In this case, it is not a simple name of the term, but the meaning described or used in the specific content for practicing the invention. The meaning should be understood by taking into account.

Hereinafter, the technical configuration of the present invention will be described in detail with reference to preferred embodiments shown in the attached drawings.

In this regard, first, Figure 1 is an overall process diagram of a method for manufacturing high-density alumina for plasma resistance using HIP according to an embodiment of the present invention, and Figure 2 is a diagram showing the process before (a) and after (b) performing the hot isostatic pressing method (HIP). ), Figure 3 is a microstructure image of the alumina sintered body before (a) and after (b) performing hot isostatic pressing (HIP), and Figure 4 shows images of the alumina sintered body before (a) and after (b) performing hot isostatic pressing (HIP). This is a comparison image of an alumina sintered body before (a) and after (b) after hole processing.

Referring to Figures 1 to 4, the method for producing high-density alumina for plasma resistance using HIP (Hot Isostatic Pressing) according to an embodiment of the present invention includes alumina powder and zirconia balls having a certain average particle size. It includes the step of putting it into a milling container.

At this time, the alumina powder may use various alumina powders, but in an embodiment of the present invention, the alumina powder uses alpha-phase alumina powder having an average particle size of 0.3㎛.

Meanwhile, the zirconia balls for milling added to the milling container are zirconia balls having a particle size different from the average particle size of the alumina powder, and the mixing ratio of alumina powder and zirconia balls is added at 1:5.

Meanwhile, the method for producing high-density alumina for plasma resistance using HIP according to an embodiment of the present invention includes adding distilled water to the milling vessel to slurry the alumina powder, and then performing primary ball milling.

At this time, distilled water added to the milling vessel can be added within a variety of ranges depending on selection, but in an embodiment of the present invention, 10 to 20 vol% of distilled water is added relative to the total volume of the alumina powder, and the zirconia added to the milling vessel is added. Ball milling is performed using balls for 24 to 48 hours.

Meanwhile, in an embodiment of the present invention, the average particle size of the alumina powder slurried through the first ball milling step described above is 0.1 μm or less.

Meanwhile, the method for producing high-density alumina for plasma resistance using HIP according to an embodiment of the present invention includes the step of performing secondary ball milling by adding a binder and a plasticizer to the slurry after the above-described primary ball milling step.

At this time, the reason for adding a binder to the slurry is to provide molding strength to the alumina powder slurry with a reduced average particle size. In an embodiment of the present invention, PVA500 is added as a binder.

In addition, the reason for adding a plasticizer to the slurry is to maintain appropriate moisture in the slurry, and in an embodiment of the present invention, PEG400 is added as a plasticizer.

Meanwhile, the above-mentioned binder and plasticizer may be added in amounts selected according to need, but in the embodiment of the present invention, 1 wt% of the binder and plasticizer are each added relative to the total weight of the alumina powder, and the second time is applied for 3 hours. Ball milled.

Meanwhile, an embodiment of the present invention includes the step of drying the secondary ball milled slurry after secondary ball milling to form spherical alumina granule powder with a certain particle size.

At this time, the step of forming spherical alumina granule powder is dried using an atomizer type spray dryer, and the particle size of the dried alumina granule powder is 80 to 100㎛.

To describe this in more detail according to an embodiment of the present invention, the first and second ball milled slurries are dried with distilled water added through a spray dryer as described above. At this time, the slurry inlet temperature of the spray dryer is 180 to 200°C. and the temperature of the outlet is maintained at 80 ~ 100℃.

In addition, the chamber pressure of the spray dryer is maintained at 4 to 8 KPa by controlling the air volume, the speed of the pump that supplies the slurry to the spray dryer is maintained at 10 to 50 rpm, and the speed of the atomizer is maintained at 8,000 to 12,000 rpm. This forms alumina granule powder with a particle size of 80 to 100㎛.

On the other hand, the method for producing high-density alumina for plasma resistance using HIP according to an embodiment of the present invention includes the step of sieving the formed alumina granule powder to remove aggregates. At this time, the alumina granule powder according to an embodiment of the present invention is In the step of removing aggregates by sieving, sieving is performed using an 80 mesh net with a sieve size of 170㎛.

Thereafter, the method for producing high-density alumina for plasma resistance using HIP according to an embodiment of the present invention includes the step of densifying the alumina granule powder from which aggregates have been removed under a certain pressure to produce an alumina molded body.

To explain this in more detail, the step of producing an alumina molded body involves first densification at a pressure of 100 to 150 kg/cm ² in a metal mold with a size of 65 mm, followed by vacuum packaging of the alumina molded body and secondary densification at a pressure of 1,500 bar. do.

On the other hand, the method for manufacturing high-density alumina for plasma resistance using HIP according to an embodiment of the present invention includes the steps of sintering the generated alumina molded body under certain conditions to produce a sintered body, and pores included in the generated alumina sintered body using hot isostatic pressure. It includes a step of removal using a pressure method.

At this time, the step of generating the alumina sintered body will be described in more detail. Using an electric furnace, the temperature is raised to 1,600°C at 1°C per minute, and then maintained at 1,600°C for 5 hours for sintering. At this time, the electric furnace is a Supercan with a MoSi ₂ heating element. By using delozing, it is possible to secure an alumina sintered body with a relative density of 99% or more.

Thereafter, the step of removing the pores contained in the alumina sintered body using hot isostatic pressing is a step to minimize the pores of the alumina sintered body having a relative density of 99% or more as described above, and is performed at 1,400 to 1,500°C. .

The method for producing high-density alumina for anti-plasma using HIP according to an embodiment of the present invention can produce high-density alumina having a relative density of 99.6% or more through the above-described steps.

In this regard, referring to (b) of FIG. 3, it can be confirmed that grain boundary pores are almost eliminated after the final step according to the embodiment of the present invention, and only some intragranular pores (powder defects) are visible.

In addition, it can be seen through Figure 4 (b) that the pores are reduced and the roughness of the finally manufactured alumina surface is improved.

As a result, the method for producing high-density alumina for anti-plasma use using HIP according to an embodiment of the present invention has an excellent effect of producing high-density alumina for anti-plasma that is translucent and has a relative density of 99.6% or more through the above-described technical configurations. .

As discussed above, the present invention has been illustrated and described by way of preferred embodiments, but it is not limited to the above-described embodiments and is intended to be used by those skilled in the art without departing from the spirit of the invention. Various changes and modifications may be possible.

Claims (9)

Injecting alpha-phase alumina powder and zirconia balls having an average particle size of 0.3㎛ into a milling container at a ratio of 1:5;
After slurrying the alumina powder by adding 10 to 20 vol% of distilled water relative to the total volume of the alumina powder in the milling container, primary ball milling is performed for 24 to 48 hours so that the average particle of the alumina powder is 0.1㎛. step;
After primary ball milling, adding 1 wt% of each PVA500 binder and PEG400 plasticizer to the slurry based on the total weight of the alumina powder and performing secondary ball milling for 3 hours;
Drying the secondary ball milled slurry with an atomizer type spray dryer to form spherical alumina granule powder with a size of 80 to 100㎛;
Sifting the formed alumina granule powder using an 80 mesh mesh with a sieve size of 170㎛ to remove aggregates;
Densifying the alumina granule powder from which aggregates have been removed under a certain pressure to produce an alumina molded body;
Producing a sintered body by heating the resulting alumina molded body at 1°C per minute to 1,600°C using a supercantalo with a MoSi ₂ heating element and then sintering the resulting alumina molded body while maintaining the temperature at 1,600°C for 5 hours; and
It includes the step of removing pores contained in the generated alumina sintered body using a hot isostatic pressing method at 1,400 to 1,500°C so that the alumina has a relative density of 99.6% or more,
The temperature of the slurry inlet of the spray dryer is 180 ~ 200 ℃ and the temperature of the outlet is maintained at 80 ~ 100 ℃, the chamber pressure of the spray dryer is maintained at 4 ~ 8 KPa by controlling the air volume, and the slurry is supplied to the spray dryer. The speed of the pump is maintained at 10 to 50 rpm and the speed of the atomizer is maintained at 8,000 to 12,000 rpm,
The step of generating the alumina molded body involves first densifying the alumina molded body at a pressure of 100 to 150 kg/cm ² in a metal mold with a size of 65 mm, followed by vacuum packaging the alumina molded body and performing secondary densification at a pressure of 1,500 bar. High-density alumina manufacturing method for anti-plasma use.
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