KR20190063400A

KR20190063400A - Method for preparing tungsten-molybdenum alloy

Info

Publication number: KR20190063400A
Application number: KR1020180142096A
Authority: KR
Inventors: 김인호; 조봉휘; 김태욱; 김상욱
Original assignee: 엔에이티엠 주식회사
Priority date: 2017-11-29
Filing date: 2018-11-16
Publication date: 2019-06-07
Also published as: KR101995377B1; WO2019107816A1

Abstract

A method for producing a tungsten-molybdenum alloy, comprising the steps of: (a) mixing tungsten oxide powder (WO ₃ ) and molybdenum oxide powder (MoO ₃ ); (b) stirring the mixture mixed in step (a) (c-1) a first reducing step of reducing the mixture at a first temperature, (c-2) a second reducing step of reducing the first reduced material at a second temperature, (c-3) A third reducing step of reducing water at a second temperature, (d) a molding step in which the reduced metal powder is put into a mold, and (e) a sintering step of sintering the formed body manufactured in step (d) Wherein the tungsten oxide powder and the molybdenum oxide powder have an average particle size of 5 to 40 μm (micrometer), the first temperature is 480 to 620 ° C., the second temperature is 570 to 740 ° C., Molybdenum alloy is in the range of 730 to 1060 ° C. The.

Description

[0001] METHOD FOR PREPARING TUNGSTEN-MOLYBDENUM ALLOY [0002]

The present application claims the benefit of priority based on Korean Patent Application No. 10-2017-0161808, filed on November 30, 2017, the entire contents of which are incorporated herein by reference.

A method for producing a tungsten-molybdenum alloy comprising the steps of: (a) mixing tungsten oxide powder (WO ₃ ) and molybdenum oxide powder (MoO ₃ ); (b) stirring the mixture mixed in step (a) (C-1) a first reducing step of reducing the mixture at a first temperature, (c-2) a second reducing step of reducing the first reduced material at a second temperature, (c-3) A third reducing step of reducing the second reduced material at a second temperature, (d) a molding step in which the reduced metal powder is put into a mold to produce a formed body, and (e) a sintering step of sintering the formed body produced in the step (d) Wherein the tungsten oxide powder and the molybdenum oxide powder have an average particle size of 5 to 40 占 퐉 (micrometers), the first temperature is 480 to 620 占 폚, the second temperature is 570 to 740 占 폚, And the third temperature is in the range of 730 to 1060 DEG C. The tungsten-molybdenum alloy manufacturing chamber Relate to.

Tungsten is a very strong metal. In the case of tungsten carbide (WC), tungsten is widely used as a high-strength material with hardness comparable to that of diamond. Molybdenum is widely used for high temperature and high pressure applications. However, tungsten has a disadvantage in that it can be easily broken if it contains impurities even though its strength is excellent, and molybdenum has a disadvantage that machining is difficult because of high mechanical strength.

On the other hand, in the case of a metal alloy, compared with a single metal material, it is possible to compensate for the disadvantages of the metal while having excellent properties of each metal, and new properties are exhibited depending on the combination. In recent metal materials, Most of them are alloy materials.

The tungsten-molybdenum alloy is a metal material that is widely used in electronic parts and aerospace fields. However, in the case of alloys produced according to the conventional alloy manufacturing method, there is a problem that the density is somewhat low. In the process of manufacturing the tungsten-molybdenum alloy, tungsten powder and molybdenum The mixing time of the powders is required for a long time.

Specifically, in order to produce a tungsten-molybdenum alloy product, tungsten powder and molybdenum powder are mixed, molded, and sintered. In this case, in order to improve the density of the alloy product in the process of mixing the metal powder, it is necessary to mill the metal powder to make the diameter and shape of each powder similar, and to mix the powders uniformly. The step of milling and mixing the powder takes a long time, and the production efficiency of the alloy is remarkably lowered.

Korean Patent No. 10-0210525 discloses a molybdenum-tungsten material for wiring formation, a molybdenum-tungsten target for wiring formation, a method of manufacturing the same, and a molybdenum-tungsten wiring thin film, and discloses a method for manufacturing a tungsten-molybdenum alloy , There is no disclosure of a method for improving the process efficiency by shortening the time required for a large-scale process, and for producing an alloy excellent in the density and strength of the alloy even in a short time.

Accordingly, there is a need to develop a technique for manufacturing a tungsten-molybdenum alloy having improved production efficiency of an alloy while improving the physical properties of the alloy as compared with the conventional tungsten-molybdenum alloy manufacturing method.

Korean Patent No. 10-0210525

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present invention at the end of a recognized the above problems and repeat a number of experiments and studies to solve this, the tungsten as molybdenum alloy production process, (a) tungsten powder (WO ₃₎ and molybdenum oxide powder oxide (MoO ₃ (C) a first reducing step of reducing the mixture at a first temperature; (c) a second reducing step of reducing the mixture at a first temperature; (C) a third reducing step of reducing the second reduced material at a second temperature, (d) a third reducing step of reducing the reduced metal powder at a second temperature, (c) And (e) a sintering step of sintering the molded body manufactured in the step (d), wherein the tungsten oxide powder and the molybdenum oxide powder have an average particle size of 5 to 40 μm (micrometer) The first temperature is 480 to 620 占 폚, the second temperature is 570 To 740 占 폚, and the third temperature is 730 to 1060 占 폚, the alloy product has an improved density and improved intermetallic bonding, resulting in high strength and corrosion resistance, and the present invention has been completed .

In order to accomplish the above object, there is provided a method for manufacturing a tungsten-molybdenum alloy, comprising the steps of: (a) mixing tungsten oxide powder (WO ₃ ) with molybdenum oxide powder (MoO ₃ ) (C-1) a first reducing step of reducing the mixture at a first temperature, (c-2) a second reducing step of reducing the mixture at the first temperature, (C-3) a third reducing step of reducing the second reduced material at a second temperature, (d) a third reducing step of reducing the reduced metal powder at a second temperature, Wherein the tungsten oxide powder and the molybdenum oxide powder have an average particle size of 5 to 40 mu m (micrometer), and the first temperature is 480 to 620 캜, the second temperature is 570 to 740 캜, And the third temperature is 730 to 1060 캜.

The tungsten oxide powder and the molybdenum oxide powder are mixed so that the tungsten content is 50 to 95 at% (atomic percent) and the molybdenum content is 5 to 50 at% (atomic percent) based on the total metal atoms constituting the mixture of the tungsten oxide powder and the molybdenum oxide powder. It can be mixed.

The step (b) may be performed for 12 to 70 minutes based on 100 g of the mixture.

The steps (c-1), (c-2), and (c-3) may be performed for 50 to 100 minutes, respectively.

The step (d) may be performed by pressing the powder at a pressure of 500 to 5000 bar while the powder is filled in the mold, and the step (e) may be performed at a temperature of 1000 to 3000 ° C.

In the method for manufacturing a tungsten-molybdenum alloy according to the present invention, the step (c-1) comprises a step of mixing 2,3-dimethyl-2-butene and Butylmethoxydibenzoylmethane in an amount of 5 to 15% by weight based on 100 parts by weight of the mixture, and the step (c-2) comprises adding the additive in an amount of 0.1 to 3 wt% %. &Lt; / RTI >

The lowest temperature of the second temperature is higher by 90 to 120 ° C than the highest temperature of the first temperature and the lowest temperature of the third temperature is higher by 160 to 320 ° C than the highest temperature of the second temperature.

The method for manufacturing a tungsten-molybdenum alloy according to the present invention has a remarkably reduced process time than the time required for a general tungsten-molybdenum alloy manufacturing process.

Further, the present invention can produce a tungsten-molybdenum alloy having an equivalent or superior level of density and strength to an alloy produced using a metal oxide having a fine particle size, thereby reducing the manufacturing cost of the alloy or pulverizing it into fine particles And the process efficiency is improved.

The tungsten-molybdenum alloy product manufactured according to the present invention has a higher density than the alloy product manufactured according to the conventional manufacturing method, and has an excellent strength and an effect of not being broken by external pressure.

Hereinafter, each configuration will be described in more detail, but this is only an example, and the scope of the present invention is not limited by the following contents.

The invention (a) a mixing step of mixing a tungsten oxide powder (WO ₃₎ and molybdenum trioxide powder (MoO _3), (b) stirring step of stirring the mixed mixture in step (a), (c-1) (C-2) a second reducing step of reducing the first reducing material at a second temperature, (c-3) a second reducing step of reducing the second reducing material at a second temperature (D) a molding step of preparing a reduced metal powder into a mold, and (e) a sintering step of sintering the compact produced in the step (d), wherein the tungsten oxide The powder and the molybdenum oxide powder have an average particle size of 5 to 40 탆 (micrometer), the first temperature is 480 to 620 캜, the second temperature is 570 to 740 캜, and the third temperature is 730 to 1060 캜 Wherein the tungsten-molybdenum alloy is a tungsten-molybdenum alloy.

The technique of making a metal material or a metal processed product by heating a metal powder or a metal oxide into a mold as in the present invention is referred to as powder metallurgy (P / M). The powder metallurgy method has the advantage that it can work at a lower temperature compared to the method of producing a molded body by casting, and that the powder can be made into a complicated shape product by a simple process in which the powder is heated in a mold at a high temperature and a high pressure.

However, the powder metallurgy method is a method of forming a formed body by heating powder to mutually bond the powders, so that it is very important in the quality of the formed body that the metal powder or the metal oxide powder has a uniform and sufficiently small particle size. Therefore, in order to improve the quality of the formed body, it is common that a considerable amount of time is required for the milling and mixing process to form a homogeneous powder of fine particles.

In the present invention, in order to improve the density of the final alloy product, instead of minimizing such a milling and mixing process, the reduction process is subdivided and the (c-1) to (c-3) By including a sequential reduction step, the manufacturing process of the alloy is simplified, and the time required and the energy invested in the process are significantly reduced.

In each reducing step, the first temperature may be 480 to 620 ° C, the second temperature may be 570 to 740 ° C, and the third temperature may be 730 to 1060 ° C.

The first temperature to the third temperature may be independently determined within a range that satisfies the above range, but it is preferable that the respective temperatures are set to be different from each other. In detail, it is preferable that the lowest temperature of the second reducing step is higher by 90 to 120 ° C than the highest temperature of the first reducing step, and the lowest temperature of the third reducing step is higher than the highest temperature of the second reducing step is 160 to 320 Lt; 0 > C.

The temperature difference between the first reducing step and the second reducing step is about 100 ° C or so so that the temperature difference between the second reducing step and the third reducing step is about 200 to 300 ° C, After the metal oxides are mixed and subjected to the first reduction process, an initial alloy state in which each metal element is heterogeneously mixed is formed. In the second reduction process, partial crystallization and partial melting are repeated to form a more homogenized intermediate alloy phase , A tungsten-molybdenum alloy powder having improved alloy homogeneity is formed through the final third reduction process. Therefore, in the case where the above-mentioned temperature condition is subjected to the reduction step, the reduction can be completed uniformly throughout the mixture.

Particularly, in the reducing step, the step (c-1) comprises adding 2,3,3-dimethyl-2-butene and butylmethoxydibenzoylmethane to the mixture obtained in step (b) 1 to 1 by weight based on 100 parts by weight of the mixture, and the step (c-2) is carried out by adding the additive in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the mixture, It is possible to obtain the effect that the reduction time is remarkably shortened and the process efficiency is further improved.

In the present invention, the tungsten oxide powder and the molybdenum oxide powder have an average particle size of 5 to 40 μm (micrometer), and include only a uniform stirring process without further milling to form finer powder. In addition, it is possible to form a uniform mixture by only stirring for a short period of time as compared with the case of mixing the powder of fine particles, and the stirring time can be remarkably shortened.

The tungsten oxide powder and the molybdenum oxide powder preferably contain 50 to 95 at% (atomic percent) of tungsten and 5 to 50 at% (atomic percent) of molybdenum based on the total metal atoms constituting the mixture of the tungsten oxide powder and the molybdenum oxide powder May be mixed as much as possible. The atomic percent is a value representing the percentage of the corresponding atom based on the total number of atoms, and the atomic percent is obtained by (number of atoms / total number of atoms) * 100. In the present invention, the number of tungsten atoms and molybdenum atoms is Is the calculated atomic percent value.

In the present invention, the step (b) may be a step of stirring for 12 to 70 minutes based on 100 g of the mixture. The time may vary depending on the amount of powder. In the case of including the process of forming fine powder particles according to the prior art and mixing them, it took about 48 hours or more to waste a lot of time and resources, whereas in the case of manufacturing according to the production method according to the present invention And stirring without milling, and mixing powder having a relatively large size in comparison with using fine powder for producing a high-quality alloy has the effect that the stirring time is remarkably shortened and the processing time is remarkably shortened . For example, it is possible to shorten the time by about 20% or more as compared with the case of mixing a metal oxide powder having a particle size of 1 mu m.

This manufacturing method is characterized in that although the method for manufacturing a tungsten-molybdenum alloy according to the present invention uses metal oxide particles having a relatively large size, the alloy powder having excellent density and strength can be obtained by carrying out a three- Which is particularly suited for use in processes in industrial facilities for the manufacture of large quantities of alloys.

Specifically, in the method for producing an alloy according to the present invention, the powder is homogeneously mixed with 100 g of the mixture of the tungsten oxide powder and the molybdenum oxide powder at a stirring speed of 100 to 150 rpm for at least 40 minutes On the other hand, in the case of stirring 1000 g of the mixture, it is possible to uniformly mix the powder uniformly only by stirring at least 280 minutes at the same speed condition. When 10000 g of the mixture is stirred, It is possible to uniformly mix the powders uniformly only by stirring for 1100 minutes, so that the process time is remarkably shortened in the process for mass production.

In the method for manufacturing a tungsten-molybdenum alloy according to the present invention, the steps (c-1), (c-2), and (c-3) may be performed for 50 to 100 minutes, respectively. Preferably, it may be performed for 55 to 95 minutes.

When the reduction is performed for a time shorter than the above-mentioned time, a sintered body finally obtained by forming a formed body using the target powder and sintering the formed body may be cracked or cracked at first, There is no difference in quality compared with the case of reducing by the above-mentioned time. Therefore, it is disadvantageous in terms of process efficiency to reduce by more than the above-mentioned time.

In the reduction process of the above three steps, the execution time of the three steps need not always coincide, and may be performed for different times in each step.

The reducing gas used in the steps (c-1) to (c-3) is a mixed gas of hydrogen (H ₂ ) and argon (Ar), and the reducing gas is used at a rate of 2000 to 6000 L / hr The reaction proceeds under the conditions.

The reduced metal powder is filled in the mold through the steps (c-1) to (c-3), and a molded body is manufactured. Specifically, the powder is filled in a mold at a pressure of 500 to 5000 bar. The powder is pressurized for 5 to 30 minutes to produce a molded article. And may be manufactured using a cold isostatic pressing (CIP).

Preferably, it is preferable to pressurize at a pressure of 1,500 to 2,500 bar for 5 to 15 minutes. When the pressure is lower than the above-mentioned pressure, the density of the formed body is lowered. Therefore, there is a problem in that the strength of the final sintered body after the sintering step is lowered. It is preferable to pressurize in the above range.

For the same reason, it is preferable that the pressing time is also performed within the above range.

The shaped body after the step (d) proceeds with the first machining to improve the precision of the final product. In the case of primary working, it is preferable to perform primary working based on the shrinkage rate of the workpiece in accordance with the sintering step and the size of the final product, taking into account that the workpiece shrinks in the subsequent sintering step. The primary machining can be carried out through a vertical shelf or a horizontal shelf.

The workpiece obtained by the primary processing of the formed body or the molded body after the step (d) is formed into a final alloy product through a step of sintering. In detail, the sintering step may be performed at a temperature of 1000 to 3000 ° C and may be performed while supplying hydrogen gas. The hydrogen gas may be supplied at a rate of 2000 to 6000 L / hr (liter / hr) depending on the time.

The temperature of the sintering step can be preferably sintered at a temperature of 2000 to 2200 ° C. The lower the sintering temperature is, the more the surface strength of the finished sintered body is lowered through the sintering step. In the case of sintering at a temperature higher than the above-mentioned temperature, there is a problem that a high temperature must be applied There is a disadvantage in terms of process time and process cost.

The method of manufacturing a tungsten-molybdenum alloy according to the present invention not only improves the production efficiency by simplifying the manufacturing process, reducing the time and material consumption in the manufacturing process, but also improving the density of the alloy Is improved and an alloy having improved strength can be produced.

Hereinafter, the present invention will be described in more detail by way of examples, which should not be construed as limiting the scope of the present invention.

Production Example 1

Tungsten oxide powder (WO ₃ ) having an average particle size of 15 μm and molybdenum oxide powder (MoO ₃ ) were mixed and stirred based on Tables 1 and 2 below.

100 g of the mixture was supplied into a mixed gas of hydrogen and argon in an atmosphere of 3000 to 5000 L / hr, followed by reduction in three steps.

The powder subjected to the reduction step was filled in a rubber mold, and then pressed with a CIP (cold isostatic pressing machine) at a pressure of 2000 bar for 10 minutes, and then the molded body was separated from the mold.

The separated compact is first processed in consideration of the sintering shrinkage of the alloy, and hydrogen gas is supplied at a temperature of 2000 to 2200 ° C in an atmosphere of 3000 to 4000 L / hr to be sintered to produce a final sintered body.

W: Mo (at%) The first temperature The second temperature Third temperature Reduction step execution time
(Step, min) Reduction Rate
(After reduction / before reduction * 100,%) Whether the reduction is complete 50:50 500 600 750 60 79.95 Some unreleased 70:30 500 600 750 60 81.03 Some unreleased 90:10 500 600 750 60 81.93 Some unreleased 50:50 600 700 800 60 77.56 Some unreleased 70:30 600 700 800 60 80.31 Some unreleased 90:10 600 700 800 60 80.85 Some unreleased 50:50 600 700 1000 60 75.33 complete 70:30 600 700 1000 60 77.16 complete 90:10 600 700 1000 60 78.73 complete

W: Mo (at%) The first temperature The second temperature Third temperature Reduction step execution time
(Step-by-step) Reduction Rate
(After reduction / before reduction * 100,%) Whether the reduction is complete 50:50 500 600 750 90 75.65 Some unreleased 70:30 500 600 750 90 78.16 Some unreleased 90:10 500 600 750 90 80.93 Some unreleased 50:50 500 600 800 90 74.98 complete 70:30 500 600 800 90 77.05 complete 90:10 500 600 800 90 79.27 complete 50:50 500 600 900 90 75.05 complete 70:30 500 600 900 90 77.53 complete 90:10 500 600 900 90 78.99 complete 50:50 600 700 900 90 76.25 complete 70:30 600 700 900 90 77.28 complete 90:10 600 700 900 90 79.14 complete

Table 1 shows the mixing ratios of tungsten oxide and molybdenum oxide and the reduction rates and the completion of the reduction depending on the temperature for each reduction step.

Referring to Table 1, when the difference between the first temperature and the second temperature is set to be about 100 ° C, and the second temperature and the third temperature are set to be about 300 ° C or so, complete reduction I could.

Referring to Table 2, when the difference between the first temperature and the second temperature is set at about 100 ° C and the second temperature and the third temperature are set at about 200 to 300 ° C, complete reduction is performed without any reduction . It was confirmed that the reduction was completed in the entire mixture even when the difference between the second temperature and the third temperature was about 200 ° C by reducing the mixture for 90 minutes in comparison with the reduction time of 60 minutes.

Production Example 2

Based on the following Tables 3 to 5, the metal oxide particles were put into a mixing ball and mixed, and then the completion of the mixing was confirmed.

On the other hand, Table 6 shows values obtained by comparing the mixing completion times of metal oxide particles having an average particle size of 1 占 퐉 (micrometer) and 50 占 퐉, respectively.

W: Mo (at%) Weight of mixture
(g) Average particle size (탆) of metal oxide Mixing Time
(min) Carbide ball presence Whether the mixture is complete 50:50 100 15 15 X X 70:30 100 15 15 X X 90:10 100 15 15 X X 50:50 100 15 30 X X 70:30 100 15 30 X X 90:10 100 15 30 X X 50:50 100 15 45 X O 70:30 100 15 45 X O 90:10 100 15 45 X O 50:50 100 15 60 X O 70:30 100 15 60 X O 90:10 100 15 60 X O

W: Mo (at%) Weight of mixture
(g) The average particle size of the metal oxide Mixing Time
(min) Mixing Time
(min / 100 g) Carbide ball presence Whether the mixture is complete 50:50 1000 15 60 6 X X 70:30 1000 15 60 6 X X 90:10 1000 15 60 6 X X 50:50 1000 15 180 18 X X 70:30 1000 15 180 18 X X 90:10 1000 15 180 18 X X 50:50 1000 15 300 30 X O 70:30 1000 15 300 30 X O 90:10 1000 15 300 30 X O

W: Mo (at%) Weight of mixture
(g) The average particle size of the metal oxide Mixing Time
(min) Mixing Time
(min / 100 g) Carbide ball presence Whether the mixture is complete 50:50 10000 15 600 6 X X 70:30 10000 15 600 6 X X 90:10 10000 15 600 6 X X 50:50 10000 15 800 8 X X 70:30 10000 15 800 8 X X 90:10 10000 15 800 8 X X 50:50 10000 15 1200 12 X O 70:30 10000 15 1200 12 X O 90:10 10000 15 1200 12 X O

W: Mo (at%) Weight of mixture
(g) The average particle size of the metal oxide Completion time
(min) Carbide ball presence Whether the mixture is complete 50:50 100 One 82 X O 70:30 100 One 90 X O 90:10 100 One 87 X O 50:50 100 50 16 X O 70:30 100 50 24 X O 90:10 100 50 30 X O

Tables 3 to 5 show the results of measuring the mixing time according to the weight of the mixture of tungsten oxide and molybdenum oxide. Table 6 shows the time taken to completely mix the metal oxides having different average particle sizes when they were stirred.

Referring to Tables 3 to 6, in the case of mixing the metal oxide having an average particle size of 15 mu m, as compared with the case of mixing particles having an average particle size of 1 mu m, the stirring time It can be confirmed that it is remarkably shortened.

On the other hand, in the case of stirring particles having an average particle size of 50 탆, the time is shortened, but the final sintered body obtained by reduction, molding and sintering using the mixture has a problem that a sintered body having uneven surfaces and cracks on its surface can be obtained .

Production Example 3

On the basis of the following Table 7, metal oxide particles having an average particle size of 15 mu m were put into a mixing ball and mixed. Thereafter, 100 g of the mixture was mixed at a first temperature of 600 DEG C, a second temperature of 700 DEG C, Lt; 0 > C, and the third reduction step was carried out for 90 minutes, the reduction step was carried out based on the following table.

The additive added in the preparation example is an additive prepared by mixing 2, 3-dimethyl-2-butene and butylmethoxydibenzoylmethane in a ratio of 1: 1, and the first reducing step And 0.5 g in the second reducing step.

W: Mo (at%) Whether the first reducing step additive is added Whether or not the second reducing step additive is added The first reduction step
Run time
(min) Second Reduction Step
Run time
(min) Reduction completed
Whether 50:50 X X 45 45 Some unreleased 70:30 X X 45 45 Some unreleased 90:10 X X 45 45 Some unreleased 50:50 O X 45 45 complete 70:30 O X 45 45 Some unreleased 90:10 O X 45 45 Some unreleased 50:50 X O 45 45 Some unreleased 70:30 X O 45 45 Some unreleased 90:10 X O 45 45 Some unreleased 50:50 O O 45 45 complete 70:30 O O 45 45 complete 90:10 O O 45 45 complete

Referring to Table 7, when the reduction step is performed for 45 minutes without the addition of the additive, some of the reduction step is partially unavailable. Even if the additive is not added in any of the first reduction step and the second reduction step, The results were.

This is because, in comparison with the case where the first reducing step and the second reducing step are performed for 90 minutes at the lower end of Table 1, the time taken until the reduction is completed is half the time in the first reducing step and the second reducing step As shown in Fig. Moreover, even when the additive is added and reduced, there is no significant difference in the strength, density, sintering shrinkage and the like of the final sintered body, and the process efficiency is greatly improved by adding the additive.

Claims

A method for producing a tungsten-molybdenum alloy,
(a) a mixing step of mixing tungsten oxide powder (WO ₃ ) and molybdenum oxide powder (MoO ₃ );
(b) stirring the mixture mixed in the step (a);
(c-1) a first reducing step of reducing the mixture at a first temperature;
(c-2) a second reducing step of reducing the first reduced material at a second temperature;
(c-3) a third reducing step of reducing the second reduced material at a second temperature;
(d) molding the reduced metal powder into a mold to produce a compact; And
(e) a sintering step of sintering the formed body produced in the step (d);
Lt; / RTI >
The tungsten oxide powder and the molybdenum oxide powder have an average particle size of 5 to 40 mu m (micrometer)
Wherein the first temperature is from 480 to 620 ° C, the second temperature is from 570 to 740 ° C, and the third temperature is from 730 to 1060 ° C.

The method according to claim 1,
The tungsten oxide powder and the molybdenum oxide powder are mixed so that the tungsten content is 50 to 95 at% (atomic percent) and the molybdenum content is 5 to 50 at% (atomic percent) based on the total metal atoms constituting the mixture of the tungsten oxide powder and the molybdenum oxide powder. Molybdenum alloy. &Lt; RTI ID = 0.0 > 11. < / RTI >

The method according to claim 1,
Wherein the step (b) is performed for 12 to 70 minutes based on 100 g of the mixture.

The method according to claim 1,
Wherein the steps (c-1), (c-2), and (c-3) are performed for 50 to 100 minutes, respectively.

The method according to claim 1,
Wherein the step (d) comprises pressing the powder at a pressure of 500 to 5000 bar while filling the mold in the mold.

The method according to claim 1,
Wherein the step (e) is performed at a temperature of 1000 to 3000 ° C.

The method according to claim 1,
In the step (c-1), the mixture obtained by the step (b) is mixed with a mixture of 2,3-dimethyl-2-butene and butylmethoxydibenzoylmethane in a ratio of 1: Is added in an amount of 5 to 15 parts by weight based on 100 parts by weight of the mixture,
Wherein the step (c-2) comprises adding the additive in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the mixture.

The method according to claim 1,
The lowest temperature of the second temperature is higher by 90 to 120 DEG C than the highest temperature of the first temperature,
Wherein the lowest temperature of the third temperature is higher by 160 to 320 占 폚 than the highest temperature of the second temperature.