JPH05117716A - Production of functional material - Google Patents

Abstract

PURPOSE:To easily and inexpensively produce a large-sized sintered functional material having high and uniform density by pulverizing >=2 kinds of raw metal powders by mechanical alloying or grinding and plasma-sintering the obtained fine powder. CONSTITUTION:An intermetallic compd. of Ti50Al50 is crushed by mechanical alloying or grinding to obtain the amorphous fine powder. The fine powder as such or the mixture of the fine powder and different kinds of materials such as ZrO2 or the bulk of the amorphous Ti50Al50 powder and ZnO2 or the mixture of the amorphous Ti50Al50 fine powder and ZrO2 and the bulk is packed in a graphite die. A compressive stress is applied, the material is plasma-sintered at 600-1000 deg.C and integrated, and a large-sized functional material having high and uniform density is inexpensively produced with a low forming pressure of about several kg/mm<2> without need for a special device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a heat resistant material for aerospace, a laminated magnetic head, a functional material used as a torque sensor, and the like.

[0002] In this specification, the term "metal" includes a semimetal. Further, the term "compound" includes alloys.

[0003]

2. Description of the Related Art Various physical properties are required for functional materials used in, for example, heat-resistant materials for aerospace, laminated magnetic heads, torque sensors and the like.

Conventionally, for example, as a material made of a compound having a high melting point, which is used as a heat-resistant material, a metal powder is used, and heat of reaction formation in a combustion reaction is utilized.
It was manufactured by the so-called combustion synthesis method. The combustion synthesis method is an inexpensive method that can simultaneously synthesize and sinter a high melting point compound without using an additive. When this method is carried out under normal pressure, the sample cannot follow the volume shrinkage during synthesis, and most of them are porous and it is difficult to densify them. The pressurized combustion synthesis method for carrying out is applied. For example, a hot press method of compressing in a uniaxial direction using hydraulic pressure, a hot isostatic press method of compressing isotropically by gas pressure or liquid pressure (H
IP), a high-pressure sintering method of compressing by a high-pressure generation technique utilizing a shock wave or centrifugal force action, and the like are applied.

However, in any of the methods,
There is a problem that the density ratio of the manufactured materials is still small and a high density cannot be obtained. Further, in order to obtain a high-density, large-scale functional material, a device capable of applying a large compressive load is required, which causes a problem of high cost. Moreover, in the case of the hot pressing method, there is a problem that the density of the formed material varies due to uneven load stress. Further, in order to manufacture a functional material having a predetermined near net shape by HIP, it is extremely difficult to manufacture a capsule because a metal capsule having a complicated shape must be used, and the encapsulation work into the capsule is also troublesome. In addition, since HIP needs to be performed in an inert gas atmosphere, a sealed device is required. Therefore, there is a problem that the cost becomes high and it is not suitable for mass production.

Further, conventionally, in the case of producing a metal carbide such as TiC, it was necessary to ignite the end of the sample forcibly, but it is difficult to install an apparatus for that and set the ignition timing, and Since the combustion temperature and the reaction rate cannot be controlled, it is difficult to make the composition uniform and control the structure.

In order to satisfy various physical properties required for functional materials used for aerospace heat-resistant materials, laminated magnetic heads, torque sensors, etc., the functional materials are entirely composed of an amorphous phase. Such as a structure, a structure in which a fine crystalline phase is uniformly precipitated in an amorphous matrix, a structure in which a fine crystalline phase on the nanometer scale exists in the amorphous matrix, or a fine crystal grain structure on the whole nanometer scale. It is effective to have a non-equilibrium phase. The non-equilibrium phase as described above is obtained by sintering the amorphous alloy powder and the dissimilar material powder, integrally sintering the amorphous alloy powder and the bulk of the dissimilar material, or the amorphous alloy powder. It has been found that it is easy from the viewpoint of the structure control to manufacture by sintering and integrating the different material powder and the bulk of the different material.

Therefore, it has been conventionally considered that one kind of rapidly solidified amorphous metal powder produced by the liquid quenching method is used to perform the sintering or the sintering integration as described above by the hot pressing method.

However, in the case of the hot pressing method, there are the same problems as in the case of producing the above-mentioned high melting point material, and since the entire powder is heated to a high temperature during sintering, the structure of the alloy portion is not desired to have a desired structure. There is a problem that it is difficult to make the equilibrium phase.

In order to solve such a problem, HIP which is a powder metallurgy method suitable for producing a high density sintered body.
It is conceivable to manufacture functional materials by
P also has the same problem as in the case of manufacturing the high melting point material, and since an oxide film is formed on the surface of the rapidly solidified amorphous powder, it is also used as an amorphous superconductor or an amorphous magnetic material by HIP. In addition to the above, there is a problem in that it is not possible to manufacture a high-density functional material that is suitable for finishing machining.

An object of the present invention is to provide a method for producing a functional material which solves all the above problems.

[0012]

The first method for producing a functional material according to the present invention is to produce finely pulverized powder by a mechanical alloying method or a mechanical grinding method using two or more kinds of raw material metal powders. It is characterized in that finely pulverized powder is sintered by a plasma sintering method.

The second method for producing a functional material according to the present invention is a method in which two or more kinds of raw material metal powders are used to produce a finely pulverized powder by a mechanical alloying method or a mechanical gliding method. It is characterized in that the material powder is sintered and integrated by a plasma sintering method.

The third method for producing a functional material according to the present invention uses two or more kinds of raw metal powders to produce a finely pulverized powder by a mechanical alloying method or a mechanical gliding method, and the finely pulverized powder is made into a different material. It is characterized in that the bulk of the material is sintered and integrated by a plasma sintering method.

A fourth method for producing a functional material according to the present invention uses two or more kinds of raw metal powders to produce a finely pulverized powder by a mechanical alloying method or a mechanical gliding method. It is characterized in that material powder and bulk of different materials are sintered and integrated by a plasma sintering method.

In the above first to fourth methods, the finely pulverized powder may be a compound of two or more kinds of metals as a raw material, or a mixture of this compound and a raw material metal. In these cases, at least a part of the compound of two or more kinds of metals as a raw material may be amorphous, or the compound of two or more kinds of metals as a raw material may be entirely crystalline.

In the above method, the mechanical alloying method or the mechanical grinding method is performed by using a device such as a ball mill. That is, two or more kinds of raw material metal powders are put in a container of a mill, and an agitator is rotated for a predetermined time in an inert gas atmosphere or a vacuum atmosphere to obtain a fine powder having an active surface. The mechanical alloying method and the mechanical grinding method are performed in an inert gas atmosphere or a vacuum atmosphere as described above, and the powder surface is always a new surface due to repetition of fracture and cold pressure welding. No oxide film is present on the surface of the powder produced by these methods. The degree of miniaturization can be controlled by controlling the time. Moreover, according to this method, it is possible to form an amorphous compound powder.

As the dissimilar material powder and the bulk of the dissimilar material, one made of one or more kinds of compounds such as metals, alloys, ceramics and the like different from the finely pulverized powder and other compounds is used. Be done. Also,
Note that ceramics include conventional ceramics such as pottery and porcelain made from silicates such as rocks, minerals, and clay, and oxides, nitrides, carbides, borides, silicides, and the like. This includes both so-called new ceramics produced under high pressure firing and other necessary conditions using synthetic materials.

Specific examples of the obtained functional material are as follows.

(1) Matrix composed of crystalline compound
Other compounds in the matrix phase, for example of an alloy.
Composite material in which object particles, for example, ceramic particles are dispersed. This is used, for example, as a magnetic material.

(2) A crystalline compound phase composed of different components
Composite material formed in a laminated state This is used as, for example, a magnetic head or a heat-resistant material for aerospace.

(3) Consist of the same components and the content of each component
Multiple crystalline compound phases with different phases are formed in a stacked state
The content of each component is from the compound phase side at one end.
Composite material gradually changing toward the compound phase side at the other end This is used, for example, as an aerospace fuselage material.

(4) Mixing two or more amorphous alloy powders
Sintered body composed of mixed powder In this composite material, there are cases where the whole is in an amorphous phase and cases where at least one kind of amorphous alloy is partially or wholly crystallized to be nanometer-scale crystals. The former is used as a soft magnetic material, for example, and the latter is used as a high frequency magnetic material, for example.

(5) From two or more amorphous alloy powders
Sintered body in which each formed layer is in a laminated state In this composite material, in the case where all amorphous alloys remain in an amorphous state,
Some amorphous alloy crystallizes partially or entirely,
In some cases, the crystal phase is on the nanometer scale. The former is used, for example, as a material for magnetic heads and sputter targets, and the latter is used, for example, as a heat-resistant material for aerospace.

(6) At least one amorphous alloy powder
Powder mixed with powder and at least one ceramic powder
In this composite material, there is a case where all amorphous alloys remain in an amorphous state and at least 1
Some amorphous alloy crystallizes partially or entirely,
It may have a nanometer-scale crystalline phase.
The former is used as, for example, a high frequency magnetic material, and the latter is used as, for example, an engine material.

(7) One end has at least one kind of amorpha
The other end is ceramics
Amorphous alloy consisting of powder only, in the middle
The amount of is gradually decreased from the above-mentioned one end side to the other end side.
On the contrary, the amount of ceramic powder is
Made of powder mixed so that it gradually decreases toward the side.
In this composite material, there is a case where all the amorphous alloys remain in an amorphous state and at least 1
Some amorphous alloy crystallizes partially or entirely,
It may have a nanometer-scale crystalline phase.
The former is used as, for example, a biomaterial, and the latter is used as, for example, an aerospace body material.

(8) At least one amorphous alloy powder
The end is sintered on at least one side of the ceramic bulk.
In this composite material, the case where all the amorphous alloys remain in the amorphous state and at least 1
Some amorphous alloy crystallizes partially or entirely,
In some cases, the crystal phase is on the nanometer scale. The former is used, for example, as a radiation resistant material,
The latter is used, for example, as a heat resistant material.

(9) The powder of (4) to (7) above is a ceramic
The bulk made of stainless steel is sintered and integrated on at least one side.
In this composite material, in the case where all the amorphous alloys remain in the amorphous state,
Some amorphous alloy crystallizes partially or entirely,
In some cases, the crystal phase is on the nanometer scale. The former is used, for example, as an electrode material, and the latter is used, for example, as a heat resistant material.

The specific examples of the functional material obtained are not limited to the above.

The plasma sintering method uses a special power source in which a high frequency is superposed on a pulse current or a direct current,
It utilizes a discharge phenomenon that occurs between powders, and gas ions generated by the discharge and charged particles such as electrons impact the contact portions between the powders for cleaning. Moreover, the evaporation of the substance at the contact portion also acts and a strong impact pressure is applied to the powder surface. Therefore, it becomes possible to sinter at a low pressure of about several kg / mm ² . Further, the electric resistance is changed depending on the length and the material of the push rod, which makes it possible to easily change the heating rate. Further, it is possible to induce combustion synthesis by utilizing a pulse current, and to synthesize and compound the compound by the exothermic reaction and plasma reaction under pressure, and at the same time, it is possible to mold and solidify.

When the fine powder is composed of an amorphous compound, the temperature and time during the plasma sintering are investigated in advance in relation to the temperature and the crystallization time when the amorphous compound powder to be used is heated. The temperature and time conditions under which the compound does not crystallize, or the temperature and time such that the crystal phase is precipitated partially or wholly by crystallization, and the amount and size of the crystal phase precipitated are desired. It is determined by obtaining the conditions in advance. For example, in the case of Co ₈₀ Nb ₂₀ ,
The relationship between the temperature and the crystallization time is as shown in the graph of FIG. In the graph of FIG. 1, the portion below the solid line (A) is an amorphous region, and the upper portion is a crystalline region.

The method of the present invention is also applicable to Ni--Ti, T
It can also be applied to various other amorphous alloys such as i-Al, Nb-Sn, and Bi-Sr-Ca-Cu. Among them, in the case of Ti ₅₀ Al ₅₀ , for example, the relationship between the heating temperature or the molding temperature and the crystallization time is as shown in the graph in FIG. In the graph of FIG. 2, the portion below the solid line (A1) is an amorphous region, and the upper portion is a crystalline region.

[0033]

According to the method of the present invention, the finely pulverized powder produced by the mechanical alloying method or the mechanical grinding method is used, and the functional material is molded by sintering by the plasma sintering method. It is possible to mold a large-scale functional material having a high density and a uniform density with a molding pressure as low as about 1 mm ² / mm ^2, a special device for applying a high pressure is not required, and the cost of the device is reduced. Further, since the plasma sintering method can be carried out in the atmosphere, there is no need for a closed type device or encapsulation in a capsule, which reduces the cost of the device and simplifies the work and makes mass production. Suitable for Therefore, it is possible to easily and inexpensively manufacture a large-sized sintered functional material having a high density and a uniform density.

Since the produced functional material has a high density,
In addition to having excellent physical properties, its strength is increased and machining becomes possible. Therefore, a material having a desired shape can be obtained from this material.

When a finely pulverized powder made of an amorphous compound is used, the crystallinity and grain size of the amorphous alloy can be adjusted by controlling the temperature, time and heating rate during plasma sintering. Therefore, functional materials having various required physical properties can be easily manufactured.

Since the finely pulverized powder is manufactured by the mechanical alloying method or the mechanical grinding method, the degree of fineness can be easily controlled. Therefore,
The compound can be easily synthesized at the same time as the production of the high density sintered body by plasma sintering. Moreover, even when a sintered body of metal carbide is obtained, the finely pulverized powder produced by the mechanical alloying method or the mechanical grinding method is plasma-sintered, so that the combustion temperature and the reaction rate can be easily controlled. Therefore, the exothermic reaction can occur at a low temperature and the structure of the compound can be easily controlled. Moreover, the ignition device is not required unlike the conventional case.

[0037]

Embodiments of the present invention will be described below.

Example 1 An intermetallic compound powder having an atomic weight ratio of Ti ₅₀ Al ₅₀ was made amorphous by a mechanical alloying method using a media stirring type ball mill to prepare an amorphous alloy powder having an average particle size of 30 μm. Next, this amorphous alloy powder and ZrO ₂ powder are mixed using a planetary ball mill, and the atomic weight ratio of both is 3: 1, 2: 1,
Mixed powders were made that were 1: 1, 1: 2, and 1: 3. These mixed powders were put into graphite dies each having an inner diameter of 20 mm, and a compressive stress of 5 kg / mm ² was applied to the dies, and 600 ° C., 700 ° C., 800 ° C., 900 ° C. and 100 ° C.
Plasma sintering was performed at each temperature of 0 ° C. for 10 minutes to form a sintered body.

The density ratio of the sintered body obtained at a sintering temperature of 700 ° C. was measured and found to be almost 100%. Further, when the sintered body was observed with a microscope, TiAl was 0.1
It was a nanometer-scale γ phase of μm or less.

Further, when X-ray diffraction was applied to the sintered body obtained at a sintering temperature of 600 ° C., TiAl was kept in an amorphous state. Moreover, although this sintered body was porous, it had sufficient mechanically processable strength.

Example 2 In the same manner as in Example 1, an amorphous alloy powder of Ti ₅₀ Al ₅₀ was prepared, and the amorphous alloy powder and ZrO ₂ powder were used and the atomic weight ratio of both was 3:
Mixed powders were made that were 1: 1, 1: 1, and 1: 3.
Ti ₅₀ Al ₅₀ amorphous alloy powder, the above ratio is 3: 1
The mixed powder having the ratio of 1: 1, the mixed powder having the ratio of 1: 1, the mixed powder having the ratio of 1: 3, and the ZrO ₂ powder were placed in this order in a graphite die having an inner diameter of 20 mm.
The thickness of each powder layer was 2 mm. And 5 kg / mm
Applying compressive stress of ² , 600 ℃, 700 ℃, 800
Plasma sintering was performed for 10 minutes at each temperature of 900C, 1000C, and 1000C to form a sintered body.

This sintered body is composed of Ti ₅₀ Al ₅₀ on one end side and ZrO ₂ on the other end side, and the amount of Ti ₅₀ Al ₅₀ gradually decreases from the one end side to the other end side in the middle part. On the contrary, the amount of ZrO ₂ was a so-called functionally graded material in which the amount gradually decreased from the other end side to the one end side.

The density ratio of the sintered body obtained at a sintering temperature of 700 ° C. was measured and found to be almost 100%. Further, when the sintered body was observed with a microscope, TiAl was 0.1
It was a nanometer-scale γ phase of μm or less.

Further, when the sintered body obtained at a sintering temperature of 600 ° C. was subjected to X-ray diffraction, TiAl was kept in an amorphous state. Moreover, although this sintered body was porous, it had sufficient mechanically processable strength.

Example 3 Co powder and Zr powder were mixed in an atomic weight ratio of Co ₈₀ Zr ₂₀ to prepare a mixed powder. Co powder and Ti powder were mixed in an atomic ratio of Co ₈₀ Ti ₂₀ to prepare a mixed powder. Co powder and Nb powder were mixed in an atomic weight ratio of Co ₈₀ Nb ₂₀ to prepare a mixed powder. Each mixed powder was amorphized by a mechanical alloying method using a media stirring type ball mill to prepare an amorphous alloy powder having an average particle diameter of 25 μm. Then, these three kinds of amorphous alloy powders were sequentially put into a graphite die having an inner diameter of 20 mm, and
Layered and loaded with a compressive stress of 15 kg / mm ² at 570 ° C., 580 ° C., 600 ° C., 630 ° C. and 650
Plasma sintering was performed for 10 minutes at each temperature of ° C to form a sintered body. When the obtained sintered body was subjected to X-ray diffraction, all layers were kept in an amorphous state. Further, the density ratio of this sintered body was measured and found to be almost 100%, indicating that the sintered body had sufficient mechanical strength for rolling.

Example 4 Nb powder and Al powder were mixed so as to have an atomic weight ratio of Nb ₃ Al ₁ and were mixed for 1 minute, 5 minutes, 30 minutes, 3 hours, 5 hours using a media stirring type ball mill. A crystalline Nb ₃ Al powder was prepared by a mechanical alloying method in which stirring and mixing treatment was performed for 10, 20 and 30 hours. The average particle size of the Nb ₃ Al powder obtained when the stirring and mixing treatment was performed for 30 hours was 100 nm.
Then, each of these Nb ₃ Al powders was treated with an inner diameter of 20
It was put in a graphite die of mm, a compressive stress of 3 kg / mm ² was applied, and the temperature was raised until the rapid exothermic reaction was completed by a pulse current at a heating rate of 50 K / min, and plasma sintering was performed. A sintered body having a diameter of 20 mm and a diameter of 20 mm was formed. When X-ray diffraction was applied to a sintered body made of each powder, synthesis of Nb-Al intermetallic compound was confirmed,
Unreacted Nb powder and Al powder did not remain. In addition, each sintered body had a true density. Further, the more the sintered body obtained by using the powder having a longer stirring and mixing treatment time, the lower the completion temperature of the abrupt exothermic reaction, and the higher the altitude and the compression strength were.

Example 5 Ti powder and amorphous B powder were mixed in an atomic weight ratio of Ti ₂ B ₁ and subjected to stirring and mixing treatment for 10 hours using a media stirring ball mill. ₂ Made B powder. Then, the Ti ₂ B powder was put into a graphite die having an inner diameter of 20 mm,
Applying compressive stress of 3kg / mm ² , heating rate 100K
Plasma sintering was carried out by raising the temperature until the rapid exothermic reaction was completed by a pulse current at a rate of 20 min / min.
A sintered body having a diameter of 20 mm and a diameter of 20 mm was formed. When this sintered body was subjected to X-ray diffraction, synthesis of an intermetallic compound of Ti-B was confirmed, and unreacted Ti powder and B powder did not remain. In addition, each sintered body had a true density.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the crystallization time and the heating temperature or molding temperature of Co ₈₀ Nb ₂₀ amorphous alloy powder.

FIG. 2 is a graph showing the relationship between the heating temperature or molding temperature of Ti ₅₀ Al ₅₀ amorphous alloy powder and crystallization time.

Claims (7)

[Claims] 1. A method of producing a finely pulverized powder by a mechanical alloying method or a mechanical gliding method using two or more kinds of raw metal powders, and sintering the finely pulverized powder by a plasma sintering method. Method of manufacturing functional material. 2. A finely pulverized powder is produced by a mechanical alloying method or a mechanical gliding method using two or more kinds of raw metal powders, and the finely pulverized powder and the different material powder are fired by a plasma sintering method. A method for producing a functional material, characterized by integrating and integrating. 3. A finely pulverized powder is produced by a mechanical alloying method or a mechanical gliding method using two or more kinds of raw metal powders, and the finely pulverized powder and a bulk of different materials are produced by a plasma sintering method. A method for producing a functional material, which is characterized in that sintering is integrated. 4. A finely pulverized powder is produced by a mechanical alloying method or a mechanical grinding method using two or more kinds of raw metal powders, and the finely pulverized powder, the different material powder, and the bulk of the different material are A method for producing a functional material, characterized in that it is integrated by sintering by a plasma sintering method. 5. The method for producing a functional material according to claim 1, wherein the finely pulverized powder is composed of a compound of two or more kinds of metals as a raw material, or a mixture of this compound and a raw material metal. 6. The method for producing a functional material according to claim 5, wherein at least a part of the compound of two or more kinds of metals which is a raw material is amorphous. 7. The method for producing a functional material according to claim 5, wherein the whole compound of two or more kinds of metals as a raw material is crystalline.