KR102084452B1 - MANUFACTURING METHOD OF Mo-Si-B ALLOY - Google Patents

Abstract

The present invention relates to a Mo-Si-B alloy, and more specifically, to the Mo ₅ SiB _two- phase alloy powder and Mo ₃ Si phase separately synthesized after the addition of molybdenum oxide (MoO ₃ ) and molybdenum (Mo) discharge plasma Mo-Si-B alloy is manufactured by spark plasma sintering. Mo ₅ SiB ₂ phase and Mo ₃ Si phase are separately synthesized to easily control the composition fraction of the alloy, and further, molybdenum oxide (MoO ₃ ) and The post addition of molybdenum (Mo) makes it easy to control the composition of the final alloy.

Description

Manufacturing Method of Mo-Si-B Alloy {MANUFACTURING METHOD OF Mo-Si-B ALLOY}

The present invention relates to a method for producing a Mo-Si-B alloy, and more specifically, Mo ₅ SiB _two- phase alloy powder and Mo ₃ Si phase alloy powder after separately synthesized molybdenum oxide (MoO ₃ ) and molybdenum (Mo) It relates to a method for producing a Mo-Si-B alloy comprising the step of adding.

One of the key components of a jet engine is the turbine blades, which are exposed to hot gases above about 1500 ° C. Nickel Base Superalloy is used to withstand these high temperatures, which can withstand up to 1200 ° C, about 90% of the melting point, which is essential for many cooling systems.

Therefore, a lot of research has been conducted to raise the operating temperature of the engine to more than 1200 ℃, there is a problem that comes with limitations due to the melting point of the material itself. In order to solve this problem, a method of lowering the use temperature through a cooling system or a heat dissipation coating has been proposed, but there is a problem that the efficiency of the engine is reduced accordingly.

Attempts have thus been made to increase the efficiency of engines through materials that can be used at high temperatures. In general, a representative intermetallic compound of molybdenum silicide (Mo-silicide) is the MoSi ₂ phase, which has a high oxidation resistance by forming a silicon dioxide (SiO ₂ ) layer on the surface when operating at high temperatures, but due to the low brittleness of the material itself, There is a problem with the back and is not suitable for jet engines.

At this time, Mo-Si-B alloy added with molybdenum (Mo), silicon (Si) and boron (B) exhibits better mechanical properties than MoSi ₂ phase and has a melting point of 2000 ° C. or higher than that of nickel-based superheat-resistant alloy. In addition, the Mo ₅ SiB ₂ phase, which is a phase caused by the addition of boron (B), is known to have a fine borosilicate layer on the surface during high temperature oxidation and has excellent thermal shock and oxidation resistance.

However, since the Mo ₅ SiB ₂ phase and Mo ₃ Si phase, which are intermetallic compounds, have insufficient mechanical properties, researches on Mo-Si-B alloy including α-Mo phase are being conducted to compensate for this problem. Efforts have been made to optimize the fraction of each component on the intermetallic compound.

In general, Mo-Si-B alloys are manufactured by casting. Such alloys have a disadvantage in that fracture toughness at room temperature is inferior because intermetallic compounds form a matrix and form a microstructure in which α-Mo phase is dispersed.

Therefore, there is an attempt to manufacture by using a powder metallurgy to compensate for these disadvantages, which may be impaired characteristics such as impurities such as oxygen or carbon is introduced into the specimen through a number of processes. Unlike casting, however, intermetallic compounds can be dispersed within a continuous α-Mo matrix.

To show such a general method, US Patent No. 5,595,616, US Patent Publication No. 2009-0011266 and the like. US Patent No. 5,595,616 uses molybdenum (Mo), silicon (Si), and boron (B) as raw materials, using arc-melting followed by gas-atomization. After preparing an alloy powder, a process of producing a Mo-Si-B alloy is proposed by using the powder through a process such as extrusion or hot isostatic molding.

In addition, U.S. Patent No. 2009-0011266 uses molybdenum (Mo), silicon nitride (Si ₃ N ₄ ), and boron nitride (BN) as raw powders, and uses a ball milling process, atmospheric sintering, and hot isostatic molding. A process for producing a final sintered body by forming silicon (Si) and boron (B) from a powdered nitrogen compound is disclosed.

In addition, Yamauchi et al.'S team used molybdenum (Mo), silicon (Si), and boron (B) powders as raw powders to sinter the ball milling process by mechanical alloying, subsequent annealing, and finally plasma discharge sintering for densification. Through the process to manufacture a Mo-Si-B alloy was disclosed.

However, the production of the Mo-Si-B alloy by arc-melting and gas-atomization forms a microstructure in which intermetallic compounds form a matrix and α-Mo is dispersed. The fracture toughness is lowered and it is difficult to implement the ideal microstructure.

In addition, in the case of a Mo-Si-B alloy manufactured by mechanical alloying method using molybdenum (Mo), silicon (Si), and boron (B) as raw materials, oxides or carbides are formed due to the inflow of impurities during the process. It can lead to degradation of the mechanical properties of the alloy.

In addition, when Mo-Si-B alloy is manufactured by the reaction using molybdenum (Mo), silicon nitride (Si ₃ N ₄ ), and boron nitride (BN) as a raw material powder, it is used as a starting material. Molybdenum (Mo) powder, which occupies the amount may be oxidized, and due to a complicated process it is difficult to control the final alloy composition.

US Patent No. 5,595,616 United States Patent Application Publication No. 2009-0011266 Korean Laid-Open Patent No. 10-2012-0044712

In order to solve the above problems, the present invention is made of Mo ₅ SiB _two- phase alloy powder and Mo ₃ Si phase alloy powder through the arc melting method (arc-melting), after the molybdenum oxide (MoO ₃ ) is an oxide of molybdenum ( It is an object of the present invention to provide a method for preparing a Mo-Si-B alloy by using molybdenum oxide (MoO ₃ ) or reducing molybdenum oxide (MoO ₃ ) as a precursor of Mo).

In addition, the present invention has another object to provide a method to make the fraction of each phase in the final alloy more easily by separately manufacturing the Mo ₅ SiB ₂ phase alloy and Mo ₃ Si phase alloy.

In order to achieve the above object, the manufacturing method of the Mo-Si-B alloy of the present invention is measured separately through an arc melting method (arc-melting) after measuring molybdenum (Mo), silicon (Si), boron (B). Alloy ingot manufacturing step of manufacturing Mo ₅ SiB _two- phase alloy ingot and Mo ₃ Si phase alloy ingot of, The alloy ingot pulverized to a fine size through the ball milling Mo ₅ SiB _two- phase alloy powder and Mo ₃ Si phase A pulverizing step of obtaining an alloy powder, a mixing step of preparing a mixed powder by mixing molybdenum oxide (MoO ₃ ) powder with the Mo ₅ SiB _two- phase alloy powder and the Mo ₃ Si phase alloy powder, the mixed powder is dried and hydrogen A reducing step of reducing molybdenum oxide (MoO ₃ ) to molybdenum (Mo) by heating in an atmosphere, and adding molybdenum powder to the reduced mixed powder and mixing to adjust the final composition of the Mo-Si-B alloy, And the molybdenum horn That the powder mixture subjected to step spark plasma sintering method (spark plasma sintering, SPS) including a sintering step for producing a Mo-Si-B alloy sintered by pressing at a high temperature can be characterized.

The alloy ingot manufacturing step, Mo ₅ SiB _2- phase alloy and Mo ₃ by heating molybdenum (Mo), silicon (Si) and boron (B) to 1400 ℃ to 1800 ℃ in an inert gas atmosphere for each composition Si phase after alloy composite heating step and the Mo ₅ SiB ₂ the alloy ingot and the Mo ₃ Si phase alloy ingot is cooled to the, cooling the Mo ₅ SiB ₂ the alloy ingot and inactivate the Mo ₃ Si phase alloy ingot It may include a cooling and reheating step of repeating the process of reheating to 1400 ℃ to 1800 ℃ under a gas atmosphere many times.

In the cooling and reheating step, the Mo ₅ SiB _2- phase alloy and the Mo ₃ Si-phase alloy are cooled to a temperature of 15 ° C. to 30 ° C. and then reheated to 1400 ° C. to 1800 ° C. under an inert gas atmosphere.

The cooling and reheating step is preferably performed three or more times to produce a homogenized Mo ₅ SiB _2- phase alloy ingot and the Mo ₃ Si-phase alloy ingot, the number of repetitions is not limited thereto.

In the crushing step, the Mo ₅ SiB _2- phase alloy ingot and the Mo ₃ Si phase alloy ingot may be pulverized into particles having a predetermined size or less using high energy ball milling in an inert gas atmosphere.

In the grinding step, the Mo ₅ SiB _two- phase alloy ingot and the Mo ₃ Si phase alloy ingot may be pulverized with a particle size of about 10 to 50 μm through high energy ball milling.

In the Mo-Si-B alloy manufacturing method of the present invention, the inert gas used in the alloy ingot production step and the pulverization step is used to prevent oxidation of the raw material powder, and any one or more selected from argon, helium and neon may be used. And argon gas may be preferably used.

In the mixing step, the molybdenum oxide (MoO ₃ ) powder or reduced molybdenum (Mo) powder is evenly mixed with the Mo ₅ SiB _2- phase alloy powder and the Mo ₃ Si phase alloy powder to prepare a mixed powder. can do.

The wet mixing is a method in which the fluid is present between the powders and thus the van der Waals force between the powders is not applied, thereby efficiently mixing the powders. In the present invention, Mo ₅ SiB ₂ The phase alloy powder, the Mo ₃ Si phase alloy powder, and the molybdenum oxide (MoO ₃ ) powder were sufficiently evenly mixed for about 10 hours.

In the reducing step, the mixed powder may be heated at 300 ° C. to 1200 ° C. for 0 to 10 hours to reduce molybdenum oxide (MoO ₃ ) to molybdenum (Mo). The time condition presented here means the heating temperature holding time after reaching the target heating temperature of the mixed powder. The heating time of 0 hours means the time of no further heating after reaching the target heating temperature of the mixed powder. Condition.

In the sintering step, the molybdenum mixed step of the mixed powder is heated to 1000 ° C to 1300 ° C temperature at a rate of 60 to 80 ° C / min by spark plasma sintering (SPS) and sintered at a pressure of 40 to 60MPa. Mo-Si-B alloy can be prepared.

According to the present invention, since the Mo ₅ SiB ₂ phase and the Mo ₃ Si phase are respectively prepared and added in the mixing step, it is easy to control the fraction of each phase, and since the Mo powder is additionally added in the Mo mixing step, It is easy to control the Mo fraction of the alloy.

In addition, another effect of the present invention is sintering is possible at a temperature of about 1000 ℃ to 1400 ℃ due to the miniaturization of the molybdenum (Mo) particles formed in the reduction step, the molybdenum (Mo ₅ SiB ₂ and Mo ₃ Si phase around By distributing Mo) particles, it is possible to realize a microstructure in which the Mo phase forms a matrix and the Mo ₅ SiB ₂ phase and the Mo ₃ Si phase exist as a dispersion.

In addition, another effect of the present invention can be applied to alloys used in a high temperature oxygen atmosphere, such as turbine blades of aerospace-jet engines, such that the desired high temperature oxidation resistance and high temperature mechanical properties through the control of the microstructure It can be applied to.

1 is a schematic flowchart of a manufacturing process of a Mo-Si-B alloy according to an embodiment of the present invention.
Figure 2 is observed with a scanning electron microscope (Scanning Electron microscope, SEM) of the Mo ₅ SiB _2- phase alloy powder 200 and Mo ₃ Si-phase alloy powder 210 after the grinding in accordance with an embodiment of the present invention It is a photograph.
Figure 3 shows the X-ray diffraction diagram of the Mo ₅ SiB _two- phase alloy powder and Mo ₃ Si phase alloy powder after the crushing progress shown in FIG.
4 is an X-ray diffraction diagram of Mo (510), Mo ₅ SiB ₂ (520), and Mo ₃ Si (530) after completely reducing molybdenum oxide (MoO ₃ ) in dry powder to molybdenum (Mo).
5 is a scanning electron microscope (Scanning Electron Microscope, SEM) analysis of the dried powder.
6 is a scanning electron microscope (Scanning Electron Microscope, SEM) analysis results after the alloy preparation.

Hereinafter, the Mo-Si-B alloy production of the present invention will be described in more detail with reference to the drawings. In the present specification, different embodiments are given the same reference numerals for the same similar components, and description thereof is replaced with the first description. As used herein, the singular forms "a", "an" and "the" include plural forms unless the context clearly indicates otherwise.

The present invention is a method for preparing a Mo-Si-B alloy by using the Mo ₅ SiB ₂ phase and Mo ₃ Si phase after the individual synthesis in order to facilitate the control of the fraction of each component in the Mo-Si-B alloy. A diagram showing this process is shown in FIG. 1.

In the present invention, the "fraction" means a mole fraction in the ratio of the content of each component in the total content of the prepared Mo-Si-B alloy.

As shown in FIG. 1, molybdenum (Mo), silicon (Si), and boron (B) are prepared using a raw powder (S110), and the prepared raw powders are each Mo ₅ SiB _2- phase alloy ingot through an arc melting method. And producing a Mo ₃ Si phase alloy ingot (S120), pulverizing the Mo ₅ SiB _two phase alloy ingot and the Mo ₃ Si phase alloy ingot to a fine size (S130), and crushed Mo ₅ SiB _two phase alloy powder Mo ₃ Si phase alloy powder mixed with molybdenum oxide (MoO ₃ ) to prepare a mixed powder (S140), reducing the molybdenum oxide (MoO ₃ ) of the mixed powder to molybdenum (Mo) (S150), the final Adding and mixing molybdenum (Mo) powder in accordance with the Mo-Si-B alloy composition (S160), and pressure sintering at high temperature through spark plasma sintering (SPS) (S170).

First, arc-melting in S120 is performed at 1400 ° C. in an argon atmosphere using molybdenum (Mo) powder, silicon (Si) powder, and boron (B) powder as raw materials. Mo ₅ SiB _2- phase alloy ingot and Mo ₃ Si-phase alloy ingot may be prepared separately by heating to a high temperature of 1800 ℃.

At this time, in order to homogenize the Mo ₅ SiB ₂ phase and Mo ₃ Si phase, the process of reheating the specimen cooled to a high temperature of 1400 ° C. to 1800 ° C. again after inverting the specimen up and down should be repeated three or more times. do.

Such Mo ₅ SiB ₂ alloy ingots and Mo ₃ Si alloy ingots can be produced by a uniform, micron (μm) composite powder by mechanical energy using high energy ball milling as in step S130.

At this time, the effect of miniaturization increases as the ball milling time passes, and the micron-grade powder is expected to contribute to the fine grains of the alloy.

The micron-level Mo ₅ SiB ₂ alloy powder and Mo ₃ Si alloy powder is mixed with molybdenum oxide (MoO ₃ ) powder (S140), and then through the reduction of molybdenum oxide (MoO ₃ ) present in the mixed powder in a hydrogen atmosphere To provide Mo (S150).

In general, molybdenum oxide such as molybdenum oxide (MoO ₃ ) is known to be reduced to molybdenum through a hydrogen reduction process in the temperature range of 600 ℃ to 1100 ℃ and the reaction scheme can be summarized as follows.

Scheme 1

MoO ₃ (s) + H ₂ (g) → MoO ₂ (s) + H ₂ O (g)

MoO ₃ (s) + 2H ₂ O (g) → MoO ₃ (OH) ₂ (g) + H ₂ (g)

MoO ₃ (OH) ₂ (g) + 2H ₂ (g) → MoO ₂ (s) + 3H ₂ O (g)

Scheme 2

MoO ₂ (s) + 2H ₂ (g) → Mo (s) + 2H ₂ O (g)

After the reduction of the molybdenum oxide (MoO ₃ ) in this way, the molybdenum (Mo) powder is added as in the final Mo composition as in step S160.

Thereafter, in step S170, the mixed powder to which molybdenum (Mo) powder is added is heated to 1000 ° C to 1300 ° C at a rate of 60 to 80 ° C / min through spark plasma sintering (SPS) to a pressure of 40 to 60MPa. Sintering is carried out to prepare a Mo-Si-B alloy.

At this time, molybdenum (Mo) forms a known phase and Mo ₅ SiB ₂ phase and Mo ₃ Si phase forms a dispersed phase. This is expected to affect the mechanical properties of the alloy.

The process for producing the Mo-Si-B alloy of the present invention is a process of making the Mo ₅ SiB ₂ phase and Mo ₃ Si phase through the arc-melting heat treatment is chemical reaction because it is reacted under argon atmosphere? Stable. Since molybdenum oxide (MoO ₃ ) is used as a precursor of molybdenum (Mo), it is similarly chemically stable until reduction. In addition, since molybdenum (Mo) is further added to the discharge plasma sintering process is also carried out in an argon atmosphere it can minimize the reaction with impurities. The Mo-Si-B alloy thus prepared has excellent mechanical properties because the fraction of each phase can be adjusted to have a desired microstructure.

EXAMPLE

1) Preparation of Mo ₅ SiB ₂ phase and Mo ₃ Si phase by arc melting method

As a raw material, Mo of purity 99.9% or more, Si of purity 99.99 or more, and B of purity 99.9 or more were used. After the arc melting, their composition is such that molybdenum (Mo), silicon (Si), and boron (B) have a molar fraction of 5: 1: 2 or 3: 1: 0, respectively. Perform arc-melting.

Thereafter, grinding is performed using high energy ball milling to refine the Mo ₅ SiB ₂ and Mo ₃ Si ingots. 2 is a result of analyzing by a scanning electron microscope (Scanning Electron microscope, SEM) of Mo ₅ SiB ₂ phase and Mo ₃ Si phase after the grinding. As shown in FIG. 2, in the SEM analysis result 200 of Mo ₅ SiB ₂ and the SEM analysis result 210 of Mo ₃ Si, it can be seen that a large particle powder and a small particle powder are mixed. The Mo ₅ SiB ₂ phase and the Mo ₃ Si phase are brittle at room temperature, so it can be confirmed that they are easily crushed even in a small amount of time milling.

3 is an X-ray diffraction diagram of the pulverized Mo ₅ SiB ₂ phase and Mo ₃ Si phase powders shown in FIG. 2. As shown in FIG. 3, the pure Mo ₅ SiB ₂ phase 400 and the Mo ₃ Si phase 410 may be present.

2) Molybdenum Oxide (MoO ₃ ) Powder Mixing and Hydrogen Reduction on Molybdenum Oxide (MoO ₃ )

The crushed Mo ₅ SiB ₂ and Mo ₃ Si powder and a predetermined amount of molybdenum oxide (MoO ₃ ) powder are ball milled with zirconia (ZrO ₂ ) balls for 10 hours using ethanol as a solvent. Thereafter, the mixed powder is dried using an evaporator, and then hydrogen reduction is performed. In the hydrogen reduction process, the dried powder is charged into an electric furnace and heated to 600 ° C to 1000 ° C while maintaining a hydrogen atmosphere, and then hydrogen reduction is performed for 2 to 4 hours.

4 is an X-ray diffractogram analysis result of Mo (510), Mo ₅ SiB ₂ (520), Mo ₃ Si (530) after completely reducing the molybdenum oxide (MoO ₃ ) in the dry powder to molybdenum (Mo). As shown in FIG. 4, the hydrogen reduction was carried out at 600 ° C. to 1000 ° C. for 2 to 4 hours to completely reduce molybdenum oxide (MoO ₃ ) to molybdenum (Mo), and the Mo ₅ SiB ₂ phase and Mo ₃ The Si phase was confirmed to be unchanged.

3) Add and mix Mo powder to match final composition

Molybdenum (Mo) is additionally added to the reduced powder to match the final composition to proceed with mixing. At this time, after milling for 10 hours using ethanol as a solvent, the mixed powder is dried using an evaporator equipment. 5 is a scanning electron microscope (SEM) analysis result of the dried powder. Relatively large particles 610 are identified as Mo ₅ SiB ₂ phase and Mo ₃ Si phase and relatively small particles 620 are identified as reduced Mo.

4) Mo-Si-B alloy production by discharge plasma sintering

Mo-Si-B alloys are manufactured by sintering under conditions of high temperature and high pressure through spark plasma sintering (SPS) on powders to which molybdenum (Mo) is additionally added. In order to prevent oxidation, sintering was performed under an argon gas atmosphere with an inert gas, and heated to 1000 ° C. at a heating rate of 70 ° C. per minute, and a pressure of 50 MPa was applied during heating.

The Mo-Si-B alloy thus prepared was shown in FIG. 6 by scanning electron microscopy (SEM) analysis. As shown in FIG. 6, the light gray portion is determined as Mo (710) phase, the dark gray portion is Mo ₅ SiB ₂ (720) phase and Mo ₃ Si (720) phase, the black portion is silicon dioxide (SiO ₂ 730 is determined. Finally, it is possible to produce a Mo-Si-B sintered body which can control the fraction of Mo phase, Mo ₅ SiB ₂ phase, and Mo ₃ Si phase through such a process.

The above-described embodiments are not limited to the above-described embodiments and the accompanying drawings, which are only preferred embodiments that allow those skilled in the art to easily carry out the present invention. Accordingly, various substitutions, changes, and changes may be made without departing from the spirit of the present invention.

Claims (10)

Molybdenum (Mo), silicon (Si), boron (B) is weighed, and then produced by alloy melting ingot (arc-melting) to produce individual Mo ₅ SiB _2- phase alloy ingot and Mo ₃ Si phase alloy ingot step;
The Mo ₅ SiB _2- phase alloy ingot and the Mo ₃ Si-phase alloy ingot were pulverized to a particle size of 10 μm to 50 μm through ball milling under an inert gas atmosphere to form an Mo ₅ SiB _2- phase alloy powder and an Mo ₃ Si phase alloy powder. Grinding step to obtain;
A mixing step of preparing a mixed powder by mixing the molybdenum oxide (MoO ₃ ) powder with the Mo ₅ SiB _2- phase alloy powder and the Mo ₃ Si phase alloy powder by a wet mixing method;
A step of reducing the molybdenum oxide (MoO ₃ ) to molybdenum (Mo) by drying the mixed powder and then performing hydrogen reduction for heating from 600 ° C. to 1000 ° C. for 2 to 4 hours in a hydrogen atmosphere;
A molybdenum mixing step of adding and mixing molybdenum powder to the reduced mixed powder to adjust the final composition of the Mo-Si-B alloy; And
A sintering step of producing a Mo-Si-B alloy by heating the mixed powder which has undergone the molybdenum mixing step to 1000 ° C. at a temperature rising rate of 70 ° C./min by spark plasma sintering and sintering at a pressure of 50 MPa; Include,
The alloy ingot manufacturing step,
Heating the metered molybdenum (Mo), silicon (Si) and boron (B) to 1400 ° C. to 1800 ° C. under an inert gas atmosphere to synthesize Mo ₅ SiB _two- phase alloy ingots and Mo ₃ Si phase alloy ingots; And
The Mo ₅ SiB ₂ the alloy ingot and the Mo ₃ Si phase alloy ingot and then cooled at a temperature 15 ℃ to 30 ℃, cooled the Mo ₅ SiB ₂ the alloy ingot and the Mo ₃ Si phase fire the alloy ingot activated gas Cooling and reheating step of repeating the process of reheating to 1400 ℃ to 1800 ℃ a plurality of times in the atmosphere; Mo-Si-B alloy manufacturing method comprising a. delete delete The method of claim 1,
The cooling and reheating step is repeated three or more times to produce a homogenized Mo ₅ SiB _2- phase alloy ingot and the Mo ₃ Si-phase alloy ingot. The method of claim 1,
The deactivation gas is Mo-Si-B alloy production method, characterized in that any one or more selected from argon, helium and neon. delete delete delete delete delete

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