KR20140072301A - High strength Aluminum Nitride ceramics and the method of low temperature sintering thereof - Google Patents

Abstract

The present invention relates to an aluminum nitride sintered body and a manufacturing method thereof, wherein the aluminum nitride sintered body is obtained by sintering a sintered material including: a transition metal oxide; a lithium source which can be converted to lithium oxide by sintering; and an alkaline earth metal oxide or rare earth metal oxide and aluminum nitride (AlN). The aluminum nitride (AlN) obtained by the present invention can be sintered at low temperatures, thereby providing improved mechanical characteristics.

Description

TECHNICAL FIELD The present invention relates to a high strength aluminum nitride (AlN) sintered body and a low temperature sintering method thereof,

The present invention relates to a high-temperature and high-strength aluminum nitride (AlN) sintered body capable of low-temperature sintering, and a method of manufacturing the same. Especially, it has excellent mechanical properties and high thermal conductivity. (AlN) sintered body and a method of manufacturing the same.

Ceramics sintered bodies are superior to conventional metal materials in terms of strength, heat resistance, corrosion resistance, abrasion resistance, light weight, and the like, and can be used for high temperature, stress, It is widely used as a mechanical part, a functional part, a structural material or a decorative material used under wear conditions.

Examples of ceramics for ceramics sintered ceramics generally used include aluminum nitride (AIN), aluminum oxide (Al ₂ O ₃ ), beryllium oxide (BeO), silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ) Due to low production costs, aluminum oxide is being produced industrially.

On the other hand, aluminum nitride (AlN) is an insulator having good thermal conductivity, and its use as a heat sink or substrate of a highly integrated semiconductor device including characteristics of low dielectric constant, dielectric loss, and thermal expansion coefficient similar to silicon .

The above-described aluminum nitride (AlN) is sinter-resisting ceramics, and sintered rare earth metal oxides such as yttrium oxide (Y ₂ O ₃ ) and calcium oxide (CaO), alkaline earth metals and the like in order to manufacture a high- A method for use as a preparation is generally used. However, in general, the sintering temperature of aluminum nitride (AlN) is higher than 1800 ° C., and thus it is difficult to sinter the alumina as compared with alumina. Accordingly, a large amount of sintering energy is required and the cost is high.

As a conventional art relating to the aluminum nitride (AlN) sintered body, Japanese Patent Application Laid-Open No. 10-1996-0703766 discloses a sintering aid composed of a rare earth metal oxide, a glass frit and an oxide such as B, Na, K, Ca, Discloses a method of producing a sintered body using an aluminum nitride (AlN) raw material powder in which a plurality of nano pores are formed, a yttrium alkoxide, a yttrium chloride, (AlN) sintered body obtained by sintering a sintering auxiliary including a vagina white room, a sulfur white room, and a calcium alkoxide.

Also, in Japanese Patent Application Laid-Open No. 10-2010-0088479, aluminum nitride (AlN) exhibiting high thermal conductivity, which is obtained by sintering a sintering aid of yttrium oxide and chromium oxide and an aluminum nitride (AlN) raw material powder at a sintering temperature of 1700 to 1800 ° C, ) Discloses a technique relating to a sintered body.

However, various methods of using a rare earth metal oxide or an alkaline earth metal oxide as a sintering assistant as a method for low temperature sintering in the process of manufacturing an aluminum nitride (AlN) sintered body including the above-described conventional techniques have been proposed to date, In order to satisfy the physical properties, the necessity of research for manufacturing aluminum nitride (AlN) sintered body capable of sintering at low temperature and having excellent mechanical strength is continuously increasing.

Patent Registration No. 10-1996-0703766 (May 25, 1999) Japanese Patent Application Laid-Open No. 10-2010-0112712 (Oct. 20, 2010) Patent Document 1: Japanese Patent Application Laid-Open No. 10-2010-0088479 (Aug.

Accordingly, the present invention provides an aluminum nitride sintered body capable of sintering at a low temperature and having improved mechanical properties.

It is another feature of the present invention to provide a novel manufacturing method for producing the aluminum nitride (AIN) sintered body having excellent mechanical properties and capable of low temperature sintering.

A) a transition metal oxide; b) a lithium source which can be sintered and converted to lithium oxide; (AlN) sintered body obtained by sintering a composition comprising a sintering assistant and an aluminum nitride (AlN) raw material powder, which comprises c) an alkaline earth metal oxide or a rare earth metal oxide.

The present invention also relates to a process for the preparation of a) a transition metal oxide; b) a lithium source which can be sintered and converted to lithium oxide; (AlN) sintered body obtained by sintering a sheet composed of a composition including a cobalt sintering aid, a sintering aid, an aluminum nitride (AlN) raw material powder and a binder, and c) an alkaline earth metal oxide or a rare earth metal oxide.

The present invention also provides an aluminum nitride (AlN) sintered body, wherein the aluminum nitride (AlN) sintered body has a thermal conductivity of 50 W / mk or more and a bending strength of 300 MPa or more.

The present invention also relates to a method of manufacturing a semiconductor device, comprising: a) a raw material powder of aluminum nitride (AlN) and a transition metal oxide; A lithium source that can be sintered and converted to lithium oxide; And an alkaline earth metal oxide or a rare earth metal oxide; b) mixing the raw material with a solvent to form a slurry; c) drying the slurry, molding the slurry, and introducing the powder into a sintering reactor; And d) sintering the reactor at a temperature of 1600 ° C or less by raising the temperature of the reactor. The present invention also provides a method of manufacturing an aluminum nitride (AlN) sintered body.

The present invention also relates to a method of manufacturing a semiconductor device, comprising: a) a raw material powder of aluminum nitride (AlN) and a transition metal oxide; A lithium source that can be sintered and converted to lithium oxide; And an alkaline earth metal oxide or a rare earth metal oxide; b) mixing the raw material with a binder to form a slurry; c) slip casting the slurry to prepare a sheet, and injecting a green sheet into the sintering reactor; And d) heating and sintering the temperature of the reactor. The present invention also provides another method for producing an aluminum nitride (AlN) sintered body.

The aluminum nitride (AlN) sintered body obtained in the present invention can be obtained by mixing a lithium source, which can be converted into lithium oxide by sintering with a transition metal oxide, with a rare earth metal oxide or an alkaline earth metal oxide to form a secondary phase during sintering The sintered body can be sintered at a low temperature in comparison with the aluminum nitride (AlN) sintered body manufactured by the prior art.

In addition, the aluminum nitride (AlN) sintered body produced by the present invention can have further improved mechanical properties and high thermal conductivity characteristics.

1 is a flowchart schematically showing a method of producing an aluminum nitride (AlN) sintered body according to the present invention.
FIG. 2 is a graph showing the relative density evaluation of an aluminum nitride (AlN) sintered body according to a sintering temperature change of an aluminum nitride (AlN) sintered body according to an embodiment of the present invention.
FIG. 3 is a graph showing a thermal conductivity evaluation of an aluminum nitride (AlN) sintered body according to a sintering temperature change of an aluminum nitride (AlN) sintered body according to an embodiment of the present invention.
4 is a graph showing the evaluation of bending strength of an aluminum nitride (AlN) sintered body according to a sintering temperature change of an aluminum nitride (AlN) sintered body according to an embodiment of the present invention.
FIG. 5 is a graph showing the relative density evaluation of an aluminum nitride (AlN) sintered body according to a sintering temperature change of an aluminum nitride (AlN) sintered body obtained according to another embodiment of the present invention.
6 is a graph showing a thermal conductivity evaluation of an aluminum nitride (AlN) sintered body according to a sintering temperature change of an aluminum nitride (AlN) sintered body obtained according to another embodiment of the present invention.
FIG. 7 is a graph showing the evaluation of bending strength of an aluminum nitride (AlN) sintered body according to a sintering temperature change of an aluminum nitride (AlN) sintered body obtained according to another embodiment of the present invention.
FIG. 8 is a graph showing the relative density evaluation of an aluminum nitride (AlN) sintered body according to a sintering temperature change of an aluminum nitride (AlN) sintered body obtained according to another embodiment of the present invention.
9 is a scanning electron microscope (SEM) image of an aluminum nitride (AlN) sintered body according to a change in sintering aid of an aluminum nitride (AlN) sintered body obtained by another embodiment according to the present invention.
10 is a graph showing the evaluation of bending strength of an aluminum nitride (AlN) sintered body according to changes in sintering aids of an aluminum nitride (AlN) sintered body obtained by another embodiment according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings of the present invention, the sizes and dimensions of the structures are enlarged or reduced from the actual size in order to clarify the present invention, and the known structures are omitted so as to reveal the characteristic features, and the present invention is not limited to the drawings . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention.

In order to provide an aluminum nitride (AlN) sintered body having superior mechanical properties and high thermal conductivity and being capable of low temperature sintering compared to a conventional sintered aluminum nitride (AlN) sintered body, b) a lithium source which can be sintered and converted to lithium oxide; (AlN) sintered body obtained by sintering a composition comprising a sintering assistant and an aluminum nitride (AlN) raw material powder, which comprises c) an alkaline earth metal oxide or a rare earth metal oxide.

The present invention also relates to a process for the preparation of a) a transition metal oxide; b) a lithium source which can be sintered and converted to lithium oxide; (AlN) sintered body obtained by sintering a sheet composed of a composition including a cobalt sintering aid, a sintering aid, an aluminum nitride (AlN) raw material powder and a binder, and c) an alkaline earth metal oxide or a rare earth metal oxide.

In the present invention, the transition metal oxide (a) is represented by the formula M _x O _y , wherein the transition metal M is applicable to the transition metal on the periodic table irrespective of the period or group, Preferably, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Lu, Hf, Ta, , Ir, Pt, Au, Hg, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg and Cn. However, X and Y may be real numbers satisfying 0 < X < 4 and 0 < Y <

In the present invention, the lithium source which can be converted into lithium oxide by sintering may be selected from lithium carbonate, lithium hydroxide, lithium halide, lithium organic acid, Li ₂ O and LiAlO ₂ .

The lithium halide may be any one of LiCl, LiBr, LiI and LiF, and the organic acid lithium may be a lithium carboxylate such as lithium acetate or lithium propionate.

In addition, any material that can form lithium oxide by bonding oxygen and lithium by sintering reaction can be used regardless of the kind.

In the present invention, the alkaline earth metal oxide may be any one selected from the group consisting of Be, Mg, Ca, Sr, Ba and Ra, which are Group 2 elements of the periodic table.

In the present invention, the rare earth metal oxide is represented by the formula Z _x O _y , where Z is at least one element selected from Sc, Y, La, Ce, Sm, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Yb, and Lu, wherein X and Y may be real numbers satisfying 0 <X <4 and 0 <Y <6, respectively.

In the present invention, a lithium-transition metal composite oxide represented by the formula LiM _w O _z may be used as a sintering aid instead of a lithium source which can be converted to lithium oxide by sintering with the transition metal oxide, wherein W and Z are May be a real number satisfying 0 < W < 4 and 0 < Z <

The content of the raw material powder of aluminum nitride (AlN) of the present invention is 80 to 99 wt%, preferably 85 to 98 wt% of the total content.

If the content of the raw material powder of aluminum nitride (AlN) is lower than 80 wt%, the content of the sintering assistant becomes high and the sintering temperature becomes high. When the content of the raw material powder is higher than 99 wt% It is difficult to achieve low-temperature sintering in a state of almost no addition, and it is possible to sinter at a high temperature by sintering at a sintering temperature of 1900 ° C or higher during the manufacturing process of the aluminum nitride (AlN) sintered body or by applying pressure in a hot press. It is preferable to use the method of the above-mentioned formula.

In the present invention, the content of the transition metal oxide is preferably 0.1 to 10 wt%, more preferably 0.3 to 3 wt% of the total composition.

In the present invention, the content of the lithium source which can be converted into lithium oxide by sintering is 0.1 to 10 wt%, preferably 0.3 to 5 wt%, based on the total amount of lithium oxide (Li 2 O) obtained by sintering . When the lithium source is added in an amount exceeding the above range on the basis of lithium oxide, the amount of the liquid phase produced during the liquid phase sintering increases, and the sinterability may be lowered, and the liquid phase may overflow on the surface of the sintered body.

Further, in the present invention, the alkaline earth metal oxide; Or rare earth metal oxides; Is 0.5 to 10 wt%, preferably 1 to 8 wt%, of the total content. Here, the total content means the total content of the raw material powder of aluminum nitride (AlN) and the oxide used as the sintering aid.

A transition metal oxide, which is a component used as the sintering aid of the present invention; and a lithium source; And excessive use of an alkaline earth metal oxide or a rare earth metal oxide may increase the thermal conductivity of the aluminum nitride (AlN) crystal grains, but the secondary phase having a low thermal conductivity is formed in a large amount, thereby increasing the thermal conductivity according to the amount of the sintering aid A decrease tendency may appear. Therefore, when the content of the sintering aid is within the above range, the activity during sintering may be excellent.

The sintered aluminum nitride (AlN) sintered body obtained by the present invention has a thermal conductivity of 50 W / mk, preferably 60 W / mk or more, a bending strength of 300 MPa or more, and preferably 400 MPa or more can do.

In the present invention, the aluminum nitride (AlN) sintered body can be produced by a method as described in FIG.

In the present invention, a method for producing an aluminum nitride (AlN) sintered body comprises: a) a step of preparing a raw material powder of aluminum nitride (AlN) and a transition metal oxide; A lithium source that can be sintered and converted to lithium oxide; And alkaline earth metal oxides or rare earth metal oxides; Preparing a raw material comprising b) mixing the raw material with a solvent to form a slurry; c) drying the slurry, molding the slurry, and introducing the powder into a sintering reactor; And d) heating and sintering the temperature of the reactor.

In the raw material preparation step a) of the present invention, an aluminum nitride (AlN) raw material powder, a transition metal oxide; A lithium source that can be converted to lithium oxide by sintering; And the alkaline earth metal oxide or the rare earth metal oxide, as described above, the content of the raw material powder of aluminum nitride (AlN) is 85 to 98 wt% of the total content, and the content of the transition metal oxide is 0.1 to 10 wt.%, and the content of the lithium source which can be converted into lithium oxide by sintering is 0.1 to 10 wt% based on the total amount of lithium oxide (Li ₂ O) obtained by sintering, and the alkaline earth metal oxide; Or rare earth metal oxides; May have an amount of 0.5 to 10 wt% of the total content.

In the step b) of forming the slurry of the present invention, the slurry may be formed by mixing a raw material and a solvent and pulverizing the entire mixture containing the raw material and the slurry through a ball mill.

More specifically, examples of the solvent include distilled water, alcohols such as ethanol, methanol and isopropanol, ketones such as hydrocarbon, acetone, and methyl ethyl ketone, etc. When distilled water is used, the characteristics of the sintered body are lowered, It is preferable to use alcohols such as isopropanol. In some cases, it may be desirable to reduce the amount of water contained in the solvent used in the present invention.

At this time, the content of the solvent used is not limited so long as it can prevent hydration or oxidation of the (AlN) raw material powder of aluminum nitride, but preferably the content of the aluminum nitride sintered material: solvent = 3: 1 to 1: 3 &lt; / RTI &gt;

In order to form the slurry, the blending ingredients are uniformly mixed and pulverized using a ball mill. The ball used for ball milling may be a ball made of ceramics such as alumina or zirconia, and the balls may be all the same size or may be used together with balls having two or more sizes. The size of the balls, the milling time, and the rotation speed per minute of the ball miller are adjusted so as to be crushed to the target particle size. The ball milling process is performed for 1 to 24 hours in consideration of the size of the target particles and the like. By means of ball milling, the blending raw material is pulverized into fine-sized particles and has a uniform particle size distribution, so that a slurry having an average particle size of 0.6 mu m to 2.0 mu m and preferably 0.9 mu m to 1.2 mu m can be formed.

In the present invention, in the slurry drying and molding step of step c), the obtained slurry can be dried by stirring on a hot plate at 100 to 120 ° C for 40 minutes to 1 hour and 30 minutes so as not to precipitate using a stirrer , And this is dried in a 60 DEG C vacuum oven for 30 minutes to 1 hour to prepare a homogeneous powder.

Or in a drying process using a rotary evaporator at a temperature of 80 to 90 DEG C and drying in a vacuum atmosphere for 1 hour and 30 minutes to 2 hours. The present invention may include a step of forming a powder by a cold isostatic pressing (CIP) method before putting the dried powder into a sintering reactor to form a disk-shaped molded body having a diameter of 30 mm and a thickness of 2.5 mm. The pressure of the cold isostatic pressing method may be in the range of 100 to 1000 atm, preferably 100 to 500 MPa.

The cold isostatic pressing (CIP) is a method in which a material such as water is used as a pressure medium, a material is put into water, and a pressure is applied at a high isostatic pressure, so that the entire surface of the substrate having a thin film is pressed. A molded article having good properties can be formed.

Further, another manufacturing method of the aluminum nitride (AlN) sintered body of the present invention is a method for manufacturing a sintered aluminum nitride (AlN) sintered body, comprising: a) a raw material powder of aluminum nitride (AlN) and a transition metal oxide; A lithium source that can be sintered and converted to lithium oxide; And an alkaline earth metal oxide or a rare earth metal oxide; b) mixing the raw material with a binder to form a slurry; c) slip casting the slurry to prepare a sheet, and injecting a green sheet into the sintering reactor; And d) heating and sintering the temperature of the reactor.

In the raw material preparation step a) of the present invention, the aluminum nitride (AlN) raw material powder, the transition metal oxide, and the lithium source; And the alkaline earth metal oxide or rare earth metal oxide may have the same content as described above.

In the step b) of forming the slurry of the present invention, the slurry may be formed by mixing a raw material, a binder and a solvent and pulverizing the entire mixture including the raw material with a ball mill to form a slurry.

More specifically, as the binder, polyvinyl butyral resin, cellulose resin, acrylic resin, vinyl acetate resin, polyvinyl alcohol resin and the like can be mainly used, but the present invention is not limited thereto.

The content of the binder in the present invention may be 3 to 20 wt%, preferably 5 to 15 wt%, based on the total mixed solution.

Further, in the present invention, a low molecular weight compound of the above-mentioned binder may be additionally used as a dispersant, and further, a solvent may be used. In this case, hydrocarbons such as toluene, xylene, benzene, and cyclohexane may be used, or alcohols such as ethanol, isopropyl alcohol, and butanol may be used, or a mixture thereof may be used.

Further, a plasticizer may be additionally used to form the slurry. The plasticizer used in this case is preferably phthalate-based, but not limited thereto.

Further, in order to form the slurry, the blending materials may be uniformly mixed and pulverized using a ball mill, and may be performed for about three to three days by primary ball milling.

Further, the binder may be further added after the ball milling process. In this case, the ball milling may be performed for 6 to 24 hours.

In the present invention, a method of slip casting the slurry obtained in step c) to prepare a sheet to form a green sheet may include the following steps.

The slip casting can be performed by forming a slurry to be injected into a mold and pouring it into a mold having a predetermined shape in order to form a solid body in a mold. In the present invention, And then gradually raising the temperature from room temperature to 600 ° C for 12 to 48 hours, followed by sufficiently removing the binder while maintaining the temperature at 600 ° C for 2 hours to 8 hours, and then gradually lowering the temperature to room temperature for 4 to 24 hours Thereby obtaining a molded article from which the binder has been completely removed.

Further, in the above step a) of the method for producing another aluminum nitride (AlN) sintered body of the present invention, instead of preparing the lithium source and the transition metal oxide, a lithium-transition metal composite oxide represented by the formula LiM _w O _z (AlN) sintered body prepared by the method of the present invention. Where W and Z are real numbers satisfying 0 < W < 4 and 0 < Z <

The lithium-transition metal composite oxide may be prepared from lithium oxide and transition metal oxide, and may be commercially available. Further, the content of the lithium-transition metal composite oxide may be the same as or different from that of each component based on the content converted to lithium oxide and the content of the transition metal oxide when each of the lithium source and the transition metal oxide is used, Can be used within the same range.

Preferably, the lithium-transition metal composite oxide may be 1 to 10 wt% based on the total amount of the aluminum nitride (AlN) raw material powder and the sintering auxiliary agent.

In the method for producing an aluminum nitride (AlN) sintered body according to the present invention, the sintering can be performed at a sintering temperature of 1600 ° C or lower in the step d).

In this case, the temperature can be raised from 20 ° C. to 40 ° C. per minute, preferably from 10 ° C. per minute, and from 1.0 ° C. to 3.0 ° C. per minute for the second production method, . In addition, the sintering temperature holding time can be from 1 hour to 10 hours, preferably from 1 hour to 5 hours in both of the two production methods.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are only for illustrating the present invention and that the scope of the present invention is not construed as being limited by these embodiments.

 <Examples>

Example 1

Two types of sintering auxiliary agents were prepared as the initial powder preparation step, which is the first step for producing the aluminum nitride (AlN) sintered body of the present invention.

Initial powder preparation A: CaO + Fe ₂ O ₃ + Li ₂ O (hereinafter referred to as LFC)

Aluminum nitride (AlN) material powder (the oxygen-containing ditch 0.85 wt%, an average particle diameter of 0.9 ~ 1.0 ㎛) 5.73 g and a sintering aid transition metal oxide is Fe ₂ O ₃ 0.12 g (purity of 99% or more, average particle diameter of about 0.6 ㎛ ), 2 wt% of alkaline earth metal oxide CaO (purity: 99% or more, average particle diameter: about 3.0 탆), and 0.03 g (0.5 wt%) of lithium oxide Li ₂ O are prepared.

Initial powder preparation B: CaO + LiFeO ₂ (Hereinafter referred to as CLF)

Instead of preparing each of the transition metal oxide and lithium oxide in the initial powder preparation A process Transition metal-as a lithium compound oxide is prepared _{LiFeO 2 0.12 g (2.0 wt%} , a purity of 99% or more, average particle diameter of about 2.0 ㎛).

As a second step, the prepared initial powders LFC and CLF are mixed with 100 ml of isopropanol as a solvent, and the raw materials are mixed and dispersed by ball milling at room temperature and 400 rpm for 24 hours using zirconia balls to prepare a slurry.

The average particle size of the obtained powder was 0.85 μm.

As a third step, the obtained slurry was stirred at 120 ° C for 1.5 hours with stirring so as not to precipitate using a magnetic bar, and it was completely dried in a vacuum oven at 60 ° C for 1 hour. 1.4 g of the dried powder was taken and formed into a disk-shaped article having a diameter of 20 mm and a thickness of 2.5 mm by a cold isostatic pressing method (CIP) under a pressure of 200 MPa.

The fourth step is a sintering step. The obtained compact is placed in a graphite crucible and then placed in a graphite furnace as a sintering reactor. In the sintering reactor, the temperature was gradually raised to 10 ° C per minute to reach the sintering temperature, and the sintering of the raw powder was proceeded.

During the sintering reaction, a nitrogen atmosphere was maintained to prevent oxidation during sintering. Examples 1-1, 1-2, 1-3, and 1-4 were sintered at different sintering temperatures at 1500 ° C, 1550 ° C, 1600 ° C, and 1700 ° C in a nitrogen atmosphere. And sintered for 3 hours each.

As a final step, the aluminum nitride sintered body obtained by sintering was recovered, and the mass of the molded body before sintering after CIP and the change in mass after sintering were measured. Finally, the aluminum nitride sintered bodies were respectively 1.4 g of Example 1-1, 1.4 g of Example 1-3, 1.4 g of Example 1-4, with an error range of about 0.02 to 0.04 g. It was confirmed that the shrinkage ratio of about 15 to 20% was obtained as a comparison between before and after sintering.

Characterization of aluminum nitride (AlN) sintered body

As a property evaluation of the aluminum nitride (AlN) sintered body obtained in the present invention, the thermal conductivity of the sintered body was evaluated by a laser flash method. The thermal conductivity of the solid material was calculated by multiplying the thermal diffusivity measured by the laser flash method and the specific heat capacity and density obtained separately. In the laser flash method, the thermal diffusivity (α) in the thickness (d) direction of the flat plate specimen is measured by pulse heating of the laser beam to the time (τ) until the temperature of the sample surface rises and the temperature of the whole sample becomes uniform Measured with a radiation thermometer.

(Measurement of Relative Density of Sintered Body)

In FIG. 2, the CLF type molded body containing 2% by weight of CaO, 2% by weight of Fe2O3 and 0.5% by weight of Li ₂ O and ₂ % by weight of CaO and 2% by weight of LiFeO ₂ is sintered at atmospheric pressure for 3 hours A relative density graph of the aluminum nitride (AlN) sintered body according to Example 1-1, Example 1-2, Example 1-3, and Example 1-4 is shown. In FIG. 2, it can be seen that the relative density of the aluminum nitride (AlN) sintered body reached the theoretical density at around 1550 ° C.

(Evaluation of thermal conductivity of sintered body)

3 is a graph of the thermal conductivity according to Example 1-1, Example 1-2, Example 1-3, and Example 1-4 of the LFC and CLF molded products manufactured in the above example, And has a thermal conductivity value of 75 W / mk or higher at a low temperature.

In general, the thermal conductivity of aluminum nitride (AlN) materials can be largely determined by two factors. One is high-thermal-conductivity aluminum nitride (AlN) crystal grains, and the other is a secondary phase element with low thermal conductivity produced by reaction with sintering aids. In the sintering process of aluminum nitride (AlN), the sintering assistant bonds with Al ₂ O ₃ of aluminum nitride (AlN) particles to form an oxide-based secondary phase, thereby reducing defects due to oxygen in the aluminum nitride (AlN) lattice, (AlN) particles. However, since the secondary phase formed at grain boundaries has a low thermal conductivity as such, it can also lower the thermal conductivity of the entire sintered body. Therefore, it is important to set the low temperature sintering temperature and sintering conditions to reduce the secondary phase with low thermal conductivity while increasing the thermal conductivity of aluminum nitride (AlN) grains to achieve high thermal conductivity. The density and the thermal conductivity of the aluminum nitride (AIN) sintered body are shown in Table 1 in more detail. As the sintering temperature increases, the thermal conductivity increases. The sintered body of aluminum nitride (AlN) prepared by sintering aluminum oxide (AlN) with lithium oxide as a sintering aid, It can be confirmed that both the density and the thermal conductivity are excellent because the crystal structure is dense and fine.

Also, it can be seen that as the density of the aluminum nitride (AlN) sintered body increases, the thermal conductivity also increases.

(Measurement of mechanical strength of sintered body)

In addition, the sintered aluminum nitride (AlN) sintered body used in the present invention was evaluated by a 3-point bending test.

The bending strength of the aluminum nitride (AlN) sintered body was evaluated by means of a 3-point bending test in order to measure the mechanical strength of the aluminum nitride (AlN) sintered body of LFC and CLF type prepared in the above example.

The sintering temperature of the aluminum nitride (AlN) sintered body was evaluated by measuring the mechanical strength in the range of 1500 캜 to 1700 캜, and the results are shown in Fig.

4, the mechanical strength of the sintered body of aluminum nitride (LNF) and the aluminum nitride (CLF) type at 1550 ° C. was evaluated to be higher than 400 MPa, and mechanical strength was maintained even at low temperature sintering.

Example  2

The procedure of Example 1 was repeated except that 1 wt% of Mn ₂ O _{3 was} used as a transition metal oxide. Finally, 1.4 g of each sintered body was produced.

Characterization of aluminum nitride (AlN) sintered body

(Measurement of Relative Density of Sintered Body)

Fig. 5 is a graph showing the relationship between a molded product of a raw material (hereinafter referred to as LMC) containing CaO 1 wt%, Mn ₂ O ₃ 1 wt% and Li ₂ O 0.5 wt% and CaO 2 (AlN) sintered body obtained by sintering a formed body of raw material (hereinafter referred to as CLM) containing 3 wt% of LiMn ₂ O _{2 and} 2 wt% of LiMn ₂ O ₂ for 3 hours under atmospheric pressure sintering (Example 2-1, Example 2-2, Example 2-3, and Example 2-4).

(Evaluation of thermal conductivity of sintered body)

6 is a graph of thermal conductivity according to Example 2-1, Example 2-2, Example 2-3, and Example 2-4 of the molded article of the LMC and CLM type manufactured in the above example, And has a thermal conductivity value of 64 W / mk or more at a low temperature.

The density and the thermal conductivity of aluminum nitride (AIN) sintered body containing Mn ₂ O ₃ as a transition metal oxide are shown in Table 2 in more detail.

As a result, it can be seen that the thermal conductivity increases as the sintering temperature rises. In the sintered aluminum nitride (AlN) sintered body obtained by sintering aluminum nitride (AlN) containing Mn ₂ O ₃ as a transition metal oxide, It can be confirmed that even if it is produced by low temperature sintering, it has characteristics of density and thermal conductivity.

(Measurement of mechanical strength of sintered body)

In FIG. 7, the bending strength was evaluated at a sintering temperature of 1500 占 폚 to 1700 占 폚 of the aluminum nitride (AlN) sintered body of the LMC and CLM type manufactured in the above example. More specifically, the bending strength in the range of 1500 MPa to 250 MPa was measured in the case of the aluminum nitride (AIN) sintered body of the LMC type, and the bending strength in the range of 150 MPa was measured in the aluminum nitride (AlN) sintered body of the CLM type.

Example 3

Except that the content of transition metal oxide and lithium oxide was changed, and in place of CaO as an alkaline earth metal, 1 wt% of Y ₂ O ₃ was used as a rare earth metal oxide, 2 wt%.

Finally, 1.4 g of the sintered body was produced.

Characterization of aluminum nitride (AlN) sintered body

(Measurement of Relative Density of Sintered Body)

8 is a graph showing the relationship between the amount of a raw material (hereinafter, referred to as &quot; LFY &quot;) containing Li ₁ O 1 wt%, Fe ₂ O ₃ 1 wt% and Y ₂ O ₃ 1 wt% And Li ₂ O 1 wt%, Fe ₂ O ₃ 2 wt%, Y ₂ O ₃ 2 wt% (hereinafter referred to as LFY_2), and Li ₂ O 2 wt%, Fe ₂ O ₃ 2 wt%, Y ₂ O ₃ (AlN) sintered body obtained by sintering a formed body of 2 wt% (hereinafter referred to as LFY_3) for 3 hours under normal pressure sintering conditions. This look at the case of the sintered aluminum nitride (AIN) that contains Y ₂ O ₃ as a rare earth metal oxide represents a relative density of 80% or more in the sintering temperature 1500 ℃, a rare earth metal oxide relative density with an increase in the content of Y ₂ O ₃ And the relative density of the aluminum nitride (AIN) sintered body increases with the increase of the content of transition metal oxide and the content of lithium oxide.

Example 4-1

(AlN) raw material powder (oxygen content 0.85 wt%, average particle diameter 0.9-1.0 mu m) 96 wt% and a transition metal oxide Fe ₂ 2 wt% of an alkaline earth metal oxide CaO (purity: 99% or more, average particle diameter: about 3.0 μm) 2 wt% O ₃ (having a purity of 99% or more and an average particle diameter of about 0.6 μm) do.

As a second step, 73 wt% of the prepared initial powder FC, 2 wt% of a dispersant and 25 wt% of a 2: 1 mixture of toluene and butanol were mixed and then subjected to primary ball milling at 91 rpm at room temperature for 24 hours using a Nylon ball, 8 wt% and 4 wt% of polyvinyl butyral resin and dioctyl phthalate as a plasticizer were added to the total amount of the mixed composition of the first ball milling, respectively, and then the raw materials were mixed and dispersed through additional ball milling for 12 hours To prepare a slurry.

As a third step, the obtained slurry was subjected to slip casting to remove the binder after sheet production. For removing the binder, the temperature was gradually raised from room temperature to 600 ° C for 29 hours. After maintaining at 600 ° C for 5 hours, the temperature was decreased to room temperature again for 8 hours to form a sheet-shaped molded article having a width of 80 mm, a length of 100 mm and a thickness of 1 mm .

The fourth step is a sintering step, in which four pieces of the obtained molded articles are laminated and placed in a sintering reactor. After elevating 1170 ℃ from room temperature at 2.5 ℃ / min in sintering reactor, it was gradually heated to 1650 ℃ at 1270 ℃ and 2.0 ℃ / min at 1.0 ℃ / min and sintered at 1650 ℃ for 3 hours.

After sintering, the sintered aluminum nitride (AIN) sintered body obtained by sintering was cooled to room temperature at a rate of 1.0 ° C / min up to 1200 ° C at a rate of 1.0 ° C / min, and the mass of the compact before sintering and the mass change Respectively.

Example 4-2

The procedure of Example 4-1 was repeated except that 95.5 wt% of aluminum nitride (AlN) raw material powder (oxygen content 0.85 wt%, average particle diameter 0.9-1.0 mu m) and transition metal oxide Fe ₂ O ₃ 2 wt% of alkaline earth metal oxide CaO (purity of 99% or more, average particle diameter of about 3.0 탆) 2 wt% and lithium oxide LiAl ₂ O (0.5 wt%) as raw materials (purity of 99% or more and average particle diameter of about 0.6 탆) (Hereinafter referred to as &quot; LFC-2 &quot;).

Example 4-3

(AlN) raw material powder (oxygen content: 0.85 wt%, average particle diameter: 0.9 to 1.0 mu m) (96 wt%) and a sintering auxiliary agent were mixed in the same manner as in Example 4-1, and a lithium-transition metal composite oxide LiMn ₂ O ₄ (Hereinafter referred to as C (LM)) of 2 wt% of an alkaline earth metal oxide (purity of 99% or more and an average particle diameter of about 0.6 탆) and 2 wt% of an alkaline earth metal oxide CaO (purity of 99% or more and average particle diameter of about 3.0 탆) Was used in the same manner as in Example 4-1.

Evaluation of the characteristics of the aluminum nitride (AlN) sintered body manufactured in Example 4

(Measurement of Relative Density of Sintered Body)

The relative density is 93.77% for Example 4-1, 92.51% for Example 4-2, and 92.06% for Example 4-3.

9 is a scanning electron microscope (SEM) photograph of Examples 4-1 to 4-3.

(Measurement of mechanical strength of sintered body)

10 is a graph showing the bending strengths of sintered aluminum nitride (AlN) sintered bodies prepared in Examples 4-1 to 4-3 at a sintering temperature of 1600 캜. More specifically, five (samples 1 to 5) sintered aluminum nitride (AlN) sintered bodies having the same conditions as in Examples 4-1 to 4-3 were prepared, and bending strengths of 400 MPa or more were all measured.

Claims (18)

a) a transition metal oxide; b) a lithium source which can be sintered and converted to lithium oxide; And (c) a sintering aid comprising an alkaline earth metal oxide or a rare earth metal oxide, and an aluminum nitride (AlN) raw material powder to obtain a sintered aluminum nitride (AlN) sintered body. a) a transition metal oxide; b) a lithium source which can be sintered and converted to lithium oxide; And
c) an aluminum nitride (AlN) sintered body obtained by sintering a sheet composed of a composition comprising a sintering auxiliary containing an alkaline earth metal oxide or a rare earth metal oxide, an aluminum nitride (AlN) raw material powder and a binder. 3. The method according to claim 1 or 2,
Wherein the transition metal oxide is represented by the formula M _x O _y .
M is at least one element selected from the group consisting of Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Lu, Hf, X, and Y are each a transition metal selected from the group consisting of Os, Ir, Pt, Au, Hg, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg, &Lt; Y < 6. 3. The method according to claim 1 or 2,
Wherein the lithium source that can be converted into lithium oxide by sintering is any one selected from lithium carbonate, lithium hydroxide, lithium halide, lithium organic acid, Li ₂ O, and LiAlO ₂ . 3. The method according to claim 1 or 2,
Wherein the alkaline earth metal is any one selected from the group consisting of Be, Mg, Ca, Sr, Ba and Ra. 3. The method according to claim 1 or 2,
Wherein the rare-earth metal oxide is represented by the formula Z _x O _y .
Wherein Z is any one selected from Sc, Y, La, Ce, Sm, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, Are real numbers satisfying 0 < X < 4 and 0 < Y < 3. The method according to claim 1 or 2,
(AlN) sintered body comprising a lithium-transition metal composite oxide represented by the formula LiMwOz instead of a lithium source which can be converted into lithium oxide by sintering with the transition metal oxide as a sintering auxiliary agent.
Here, W and Z are real numbers satisfying 0 < W < 4 and 0 < Z < 3. The method according to claim 1 or 2,
The content of the raw material powder of aluminum nitride (AlN) is 85 to 98 wt%
The content of the transition metal oxide is 1 to 10 wt% of the total content,
The content of the lithium source which can be converted into lithium oxide by sintering is 0.3 to 5 wt% of the total content based on the lithium oxide (Li 2 O) obtained by sintering,
An alkaline earth metal oxide; Or rare earth metal oxides; (AlN) sintered body according to the present invention is characterized in that the content of any one selected from AlN is 1 to 8 wt% of the total content. (AlN) sintered body having a thermal conductivity of 50 W / mk or more and a bending strength of 300 MPa or more. a) a raw material powder of aluminum nitride (AlN) and a transition metal oxide; A lithium source that can be sintered and converted to lithium oxide; And alkaline earth metal oxides or rare earth metal oxides; Preparing a raw material comprising
b) mixing the raw material with a solvent to form a slurry;
c) drying the slurry, molding the slurry, and introducing the powder into a sintering reactor; And
and d) heating and sintering the temperature of the reactor. a) a raw material powder of aluminum nitride (AlN) and a transition metal oxide; A lithium source that can be sintered and converted to lithium oxide; And an alkaline earth metal oxide or a rare earth metal oxide;
b) mixing the raw material with a binder to form a slurry;
c) slip casting the slurry to prepare a sheet, and injecting a green sheet into the sintering reactor; And
and d) heating and sintering the temperature of the reactor. 11. The method of claim 10,
Wherein the step of forming the slurry in step b) comprises mixing a raw material and a solvent, and pulverizing the entire mixture including the raw material and the slurry through a ball mill to form a slurry. 11. The method of claim 10,
The method for manufacturing an aluminum nitride (AlN) sintered body according to claim 1, wherein in step (c), a powder is formed by cold isostatic pressing (CIP) before the slurry is dried and then introduced into a sintering reactor. 12. The method of claim 11,
The step of forming the slurry in the step b) includes mixing the raw material, the binder and the solvent, and pulverizing the entire mixture including the raw material with a ball mill to form a slurry. (Method for manufacturing sintered body). 12. The method of claim 11,
Wherein the step (c) further comprises a step of slip casting the obtained slurry to remove the binder after the production of the sheet. 15. The method according to claim 12 or 14,
Wherein the particles formed through the ball mill have a particle size range of 0.1 to 10 占 퐉 or less. The method according to claim 10 or 11,
In step (a), an aluminum nitride (AlN) sintered body is prepared by preparing a lithium-transition metal composite oxide represented by the formula LiMwOz instead of preparing a lithium source and a transition metal oxide which can be converted into lithium oxides by sintering (AlN) sintered body according to the present invention
Here, W and Z are real numbers satisfying 0 < W < 4 and 0 < Z < The method according to claim 10 or 11,
Wherein the step of sintering in step d) is performed at a temperature of 1600 ° C or less.

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