JPH09131828A - Functionally graded material and manufacturing method thereof - Google Patents

Abstract

(57) Abstract: A metal having a higher sintering temperature is used, and a functionally graded material composed of the metal and a polymer material and a method for producing the same are provided. Kind Code: A1 A functionally gradient material composed of a polymer material having no thermoplasticity and a metal, and having at least a layer composed of only the metal, a layer containing both of the metal and the polymer material, and a layer composed of the polymer material. Configured. In addition, the composition ratio of the metal and the polymer material is continuous or stepwise between the layer composed only of the metal and the layer composed only of the metal, which is composed of the polymer material having no thermoplasticity and the metal. A functionally graded material was constructed with an intermediate layer that changed to. These functionally graded materials are filled in a mold while mixing powder particles of a polymer material having no thermoplasticity and powder particles of a metal at different ratios and changing the ratio continuously or stepwise. After that, it was manufactured by molding by a discharge plasma sintering method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a functionally graded material and a method for producing the same, and more particularly to a high heat resistant polymer / metal functionally graded material.

[0002]

2. Description of the Related Art A functionally graded material is generally formed by combining two kinds of materials having different properties, and is formed in the middle of a single layer so that the ratio of both components changes continuously or stepwise. Development is underway as a new functional material. Various methods such as a sintering method, a thermal spraying method, and a CVD / PVD method are adopted in the production of this functionally graded material. Among these, there is a high degree of freedom regarding the size of a molded body that can be produced. Moreover, the sintering method is suitable as a method for obtaining a relatively large compact. Conventionally, the functionally gradient material produced by this sintering method has been mainly a metal / ceramic system or a ceramic / ceramic system.

By the way, in recent years, instead of ceramics,
Due to the excellent properties of thermoplastic polymers, functionally graded materials using thermoplastic polymers that are usefully used in various fields are under development, and thermoplastic polymers / metallic functionally graded materials are proposed. Has been done. This is because, among the organic polymers, the thermoplastic polymer has a melting point or a softening point, and when heated to a certain temperature or higher, it becomes fluid and can be molded by various methods. More specifically, functionally graded materials of fluororesin and metal (Japanese Patent Publication 5-1
No. 8860) and functionally graded materials (New Ceramics 1994, No. 7, p27) made of a thermoplastic polyimide having high heat resistance as a polymer material and a metal having a low sintering temperature have been proposed.

[0004]

However, the biggest problem in producing such a thermoplastic polymer / metal functionally gradient material is to simultaneously densify and mold both materials having different sintering temperatures. Especially. However, when a thermoplastic polymer is used, if the temperature and pressure during sintering are increased, the resin will flow out, so there is a limit to the densification. Also, even after the thermoplastic polymer is molded,
There is also a problem that it cannot be used in applications requiring heat resistance because it softens at a certain temperature or higher. Furthermore, there is a limit to the temperature that can be heated due to the heat resistance of the polymer, and therefore, the metals that can be used are less than that temperature, that is, only very limited metals such as silver that have a relatively low sintering temperature of 400 ° C. or less. Met.

On the other hand, among the organic polymers, the non-thermoplastic polymer basically has the same softening point as that of the thermoplastic polymer, but does not have a softening point and starts to decompose. The temperature is also high. Therefore, it has very high heat resistance and can be used in a wide range of applications, so that it can be used in a wide range of fields. However, since this non-thermoplastic polymer does not soften by heat, it was difficult to mold it. In addition, since it is difficult to precisely mold both metal and non-thermoplastic polymers by conventional sintering methods and other molding methods, non-thermoplastic polymers have hitherto been used as functionally graded materials. It was not considered an element.

However, the present inventors have paid attention to the excellent properties of non-thermoplastic polymers, and by using non-thermoplastic polymers with high heat resistance, it is possible to use metals with higher sintering temperatures. Therefore, by obtaining a functionally graded material by both of them, it becomes possible to provide a highly functional functionally graded product, and therefore, the present inventors made extensive efforts for research and development. As a result, the present inventors have used a non-thermoplastic polymer and a metal, which have not been considered so far, as the functional elements of the functionally gradient material, and by using the spark plasma sintering method, the non-thermoplastic polymer can be treated at a relatively low pressure. The inventors have found that both the plastic polymer and the metal are densely molded, and have arrived at the present invention.

[0007]

The gist of the functionally gradient material according to the present invention is that it is composed of a polymer material having no thermoplasticity and a metal, at least a layer composed only of the metal, a metal and the polymer material. It is to have a layer containing both of them, and a layer made of only a polymer material.

Another feature of the functionally gradient material according to the present invention is that it is composed of a polymer material having no thermoplasticity and a metal, a layer composed only of the metal and a layer composed only of the polymer material. And an intermediate layer in which the component ratio of the metal and the polymer material changes continuously or stepwise.

Further, in such a functionally gradient material, the metal has a sintering temperature not higher than about 100 ° C. higher than the thermal decomposition temperature of the polymer material, more preferably not higher than the thermal decomposition temperature of the polymer material. Is to be.

Furthermore, in such a functionally graded material, the metal is copper or aluminum.

Further, in the functionally gradient material, the polymer material having no thermoplasticity is a non-thermoplastic polyimide.

Next, the gist of the method for producing a functionally graded material according to the present invention is to mix powder particles of a polymer material having no thermoplasticity and powder particles of a metal at different ratios. This is to fill the mold while changing the ratio continuously or stepwise, and then mold by the spark plasma sintering method.

Further, in the method of manufacturing such a functionally gradient material, the powder particles of the polymer material and the powder particles of the metal are filled in the mold while diffusing by a centrifugal separation method.

Further, in the method of manufacturing a functionally gradient material, the powder particles of the polymer material and the powder particles of the metal are filled in a mold while applying vibration.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of a functionally graded material and a method for manufacturing the same according to the present invention will be described in detail with reference to the drawings.

The functionally gradient material according to the present invention is composed of a so-called non-thermoplastic polymer material having no thermoplasticity and a metal, at least a layer consisting of only the metal, a layer containing both the metal and the polymer material, and a high functional material. An intermediate layer in which the composition ratio of the metal and the polymer material changes continuously or stepwise between the layer composed of only the metal material and the layer composed of only the metal and the polymer material. It is configured with layers. Then, all of these layers are sintered and integrally formed as a whole.

Here, the functionally gradient material in the present invention is composed of a plurality of components, that is, component A and component B, as shown in FIG. 1, and the composition of each component A and B changes continuously and linearly. However, the composition of each of the components A and B is continuously and curvedly changed as shown in FIG. Further, it also includes those in which the change in the composition of each of these components A and B is minutely stepwise. Further, as shown in FIG. 3, those in which the composition of each of the components A and B changes stepwise are also included. Then, as an extreme case of the example shown in FIG.
3 layers and a layer containing both components in a fixed ratio between them
A layer structure or, for example, as shown in FIG.
In the intermediate layer between the component A layer and the component B layer, those in which the ratio of both components continuously changes are also included. In addition, for example, as shown in FIG. 5, a layer containing only the component A is formed at both ends, and a layer containing only the component B is formed in the middle of the layers, and the layer containing only the component A and the layer containing only the component B are formed. Includes a layer in which the composition of each of the components A and B changes continuously or stepwise, and a combination of various examples is also possible. In the above constitution, the component A and the component B represent either a non-thermoplastic polymer material or a metal.

Since the non-thermoplastic polymer material is used as the polymer material constituting the functionally gradient material of the present invention, the sintering temperature is higher than that when a thermoplastic resin is used.
Both the pressure and the pressure can be set to be high, so that a metal having a high sintering temperature, which cannot be used in the conventional polymer / metal functionally gradient material, can be used. That is, since the heat resistance of the non-thermoplastic polymer material is high,
Higher performance materials can be obtained as the functionally gradient material.

As described above, a higher sintering temperature is used as compared with the case where the thermoplastic polymer material is used, but if the sintering is performed at a temperature higher than the decomposition temperature of the non-thermoplastic polymer material. However, the performance of the finished functionally graded material may deteriorate. Therefore, the sintering temperature applied to the portion of the non-thermoplastic polymer material is preferably not higher than the decomposition temperature of the polymer. However, as will be described later, in the spark plasma sintering method, it is possible to make a difference in temperature between the metal part and the polymer material part by devising the shape of the mold to be used. It is possible to set the sintering temperature of the part high and simultaneously set the sintering temperature of the polymer material part low, which means that a higher sintering temperature can be used for each.

It is considered that the limit that can be set as the temperature difference between the metal portion and the polymer material portion is about 100 ° C., and the sintering temperature of the metal that can be used as a component of the functionally gradient material is high in non-thermoplasticity. About 100 ℃ from the thermal decomposition temperature of molecular materials
It is necessary that the temperature is not higher than a moderately high temperature, more preferably not higher than the thermal decomposition temperature. Since most industrially useful non-thermoplastic polymer materials have a decomposition temperature of 500 ° C. or lower, the sintering temperature of the metal used is preferably 600 ° C. or lower,
Further, it is preferably 500 ° C. or lower, which is lower than the thermal decomposition temperature of the non-thermoplastic polymer material. As the metal having such a sintering temperature, specifically, aluminum, copper, brass,
Examples of such metals include magnesium, which are industrially extremely versatile, and from the viewpoint of strength, thermal conductivity, and electrical conductivity, copper and aluminum are particularly preferred as metals having high value in combination with polymers. .

The term "non-thermoplastic" or "non-thermoplastic" means that it is difficult to detect a clear melting point or softening point by TMA, a dynamic viscoelasticity measuring device, or the like. Even if a clear melting point or softening point can be detected by a dynamic viscoelasticity measuring device or the like, if it does not cause softening to produce fluidity, the temperature is 400 ° C or higher and the softening temperature and decomposition are sufficiently high. This includes cases where the temperature is close and thermal molding is difficult with conventional molding methods.

More specifically, examples of the non-thermoplastic polymer include aromatic polyimide, aromatic polyamide, various aromatic ladder polymers, or aromatic thiazole 5-membered ring / aromatic oxazole 5-membered ring / aromatic. Examples thereof include polymers having an imidazole 5-membered ring, high molecular symmetry and rigidity, and exhibiting non-thermoplasticity, and copolymers and blends thereof. Among these, aromatic polyimide exhibits particularly excellent properties when it is used as a functionally gradient material in combination with a metal because of the excellent heat resistance, chemical resistance, mechanical properties, and electrical properties of the resin itself.

Needless to say, since these non-thermoplastic polymer materials are materials that do not have plasticity by heating, they cannot be heated and melted to form a functionally gradient material like the thermoplastic polymer materials. The functionally gradient material of the present invention was completed by discovering that it is possible to densify at a low temperature and a relatively low pressure by a discharge plasma sintering method using a non-thermoplastic polymer material. First, a method of manufacturing a functionally gradient material according to the present invention will be described.

Here, in the discharge plasma sintering method, pulsed electric energy is directly injected into the gap between the powder particles, and the high energy of high temperature plasma generated instantaneously by the spark discharge is effective for thermal diffusion, electric field diffusion and the like. By applying it, the temperature is much lower than the conventional method (hot press method) in the ultra-high temperature range from low temperature to 2000 ° C or higher, and the heating and holding time is about 5 to 20 minutes. This is a material synthesis processing technology that has been put into practical use in recent years and enables the short-time sintering or sinter bonding. More specifically, the spark plasma sintering method is a method of hot pressing by direct energization using a graphite type or a sintered metal, a WC-based cemented carbide material, a BN composite EC or the like as a resistor. As shown in FIG. 6, an example of the spark plasma sintering device is a press device 1 including a hydraulic device 10.
2, a lower electrode 14 and an upper electrode 16 are provided, a lower punch 18 and an upper punch 20 are provided, and further, a vacuum chamber, a power supply device, and various control devices are provided. Then, the mixed powder particles 24 placed in the mold 22 are pressed by the lower punch 18 and the upper punch 20 and sintered by discharge plasma.

As described above, when it is desired to make a temperature difference between the material layers of the non-thermoplastic polymer material layer and the metal layer, which are put in the mold 22, as shown in FIGS. 7 and 8, for example. It can be realized by using a graphite heating body composed of different types of molds 26 and 28 as described above. Especially when a functionally graded material is manufactured from two materials having different sintering temperatures,
It is necessary to use this type of mold.

The method for producing a functionally graded material according to the present invention comprises:
Mainly, (1) a process of mixing powder and granules, (2) a process of adding a mixture of powder and granules to a graphite mold, (3) a process of pre-compressing and molding the mixture of powder and granules in a graphite mold (4) It is manufactured by the process of sintering by the discharge plasma sintering method. In this manufacturing method, the step (3) can be omitted in some cases, and the steps (1) and (2) can be simultaneously performed.

More specifically, first, in the (1) powder / granule mixing step, the powder / granule of the non-thermoplastic polymer material (A component) and the metal powder / granule (B component) are mixed. However, it is more preferable to use both components having a particle size distribution as small as possible. Then, a mixed powder or granular material having an arbitrary composition can be obtained by variously changing the mixing ratio of the powder or granular materials of both the components A and B.

The mixing ratio of the powder and granules is not particularly limited, but as a method for producing a functionally graded material in which the components change stepwise, a layer made of only non-thermoplastic polymer powder and a metal An example will be described in which a stepwise functionally gradient material is formed in a stepwise manner, for example, a mixed layer of four layers, in the middle of the layer made of only the granular material. In this case, for example, (A component 100%), (A component 80%: B component 20
%), (A component 60%: B component 40%), (A component 40
%: B component 60%), (A component 20%: B component 80
%) And (B component 100%) and the mixture thereof, a mixed powder for forming each layer can be obtained. As a mixer for adjustment, a ball mill, a rod mill, a double coat blender, a V-type mixer, or the like can be used.

Next, (2) in the step of introducing the powder or granular material into the graphite mold, the single powder or granular material and the mixed powder or granular material are sequentially charged into the graphite mold. At this time, each component is added. It is preferable to add the next mixed powder or granular material after performing preliminary pressurization each time. In this way, by performing pre-pressurization for each component, it is possible to obtain a functionally graded material with clear boundaries, but by applying each component without pre-pressurizing and then applying vibration, etc. Thus, a stepwise functionally graded material with unclear boundaries can be obtained.

Although the above is the method of manufacturing the stepwise functionally gradient material, it is also possible to obtain a functionally gradient material in which the mixing ratio of the components continuously changes. For example, by preparing a mixed powder or granular material in which the mixing ratio of each component is further finely changed, a more continuous functional change can be brought about. Further, for example, as shown in FIG. 9, the A component 30 and the B component 3
It is also possible to adopt a method in which 2 is continuously fed to the mixing device 34 while the supply amount is being changed, stirred and mixed, and this is continuously or batchwise charged into the mold 36.

Although not shown in the figure, similar to the method for producing the density gradient tube, a small amount of a constant amount of B component is fed to a mixing device in which a constant amount of A component is put and mixed. It is also possible to use a method in which both components A and B are mixed at a sufficient speed in an apparatus, and at the same time, a uniform powder mixture is continuously fed into the mold.

Furthermore, it is also possible to continuously change the A component and the B component by the centrifugal separation method. That is, both components A and B are once uniformly mixed and then put into a mold, and then both components A and B are centrifuged in the mold to form a gradient in the mixing ratio of both components A and B. Of. In addition, as another method, by vibrating the uniformly mixed powder of the component A and the component B, the heavy metal component is continuously moved downward so that both components A and B are mixed.
It is also possible to form a gradient in the mixing ratio of.

After introducing all the powder particles by such a method, (4) spark plasma sintering is performed under pressure. Pressure during sintering is 10 to 200 MPa, preferably 20 to 100 MP
a. When the pressure is lower than this, there is a problem in the compactness of the sintered body, and when the pressure is higher than this, there is a problem in the resistance of the graphite type. Further, the sintering temperature is appropriately determined depending on the heat resistance of the non-thermoplastic polymer material, that is, the thermal decomposition temperature and the sintering temperature of the metal, as described above.

In this discharge plasma sintering method, plasma is generated by directly energizing the graphite mold 22, and a voltage value of 0.1 to 20 V, preferably 1 to 5 V, 10
It is possible to sinter by generating plasma by repeating ON / OFF DC pulse energization in mS (millisecond) unit at a current value of 10000A, preferably 103000A. Here, in air, oxygen, water, etc. may adversely affect metals and polymer materials, and because the generation of plasma in the mold may be impeded, precise molding may not be possible. It is preferable that the sintering furnace is depressurized before the sintering and the sintering is also performed under the reduced pressure. Further, for the same reason, it is also possible to carry out in an inert gas.

Further, when performing the plasma sintering, the temperature inside the mold 22 is raised to a predetermined temperature. When raising the temperature, it takes about 1 to 15 minutes to reach the maximum temperature, and the maximum temperature is reached. After the temperature is maintained for 1 to 30 minutes, it is gradually cooled to take out the sintered functionally graded material from the mold 22. In this case, the maximum temperature at the time of sintering needs to be experimentally found to be the maximum temperature at which sufficiently dense molding can be performed within a range in which the resin does not decompose.

As described above, the functionally graded material according to the present invention can be produced, and by applying the discharge plasma sintering method, it has a very high heat resistance in the past, but it is not softened by heat and thus molded. It is possible to mold a non-thermoplastic polymer material that has been difficult to process at a very low pressure, and it is possible to easily process even a relatively large molded body. The molded product obtained by such a method is excellent in compactness and is a strong product that is not easily chipped.

Although the embodiments of the functionally gradient material and the manufacturing method thereof according to the present invention have been described above, the present invention is not limited to these embodiments. For example, in the above description, two components were described, but three or more components,
For example, it is also possible to obtain the non-thermoplastic polymer material / metal / ceramic in the order of the powder particles and the mixed powder particles, and perform spark plasma sintering to obtain an integrated functionally graded material. In addition, the present invention can be carried out in a mode in which various improvements, changes and modifications are made based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

Examples of using aromatic polyimide and aluminum will be shown below to specifically explain the content of the present invention, but the present invention is not limited to these examples.

[0039]

EXAMPLES First, a method for producing an aromatic polyimide powder used as an example of the non-thermoplastic polymer material used in the present invention will be described. Under a nitrogen stream, N, N-
In a mixed solution of dimethylacetamide (hereinafter, referred to as DMAc) and pyridine (volume ratio 1: 1), the same molar amount of
A polyamic acid solution is obtained from 4,4'-diaminodiphenyl ether and pyromellitic dianhydride. Next, the obtained polyamic acid solution is heated and continuously heated and stirred to precipitate insolubilized polyimide as a powder. After allowing to cool, the powder obtained by filtration is repeatedly washed and filtered in the order of DMAc and methanol, and further, under nitrogen, in order to complete imidization and drying, heat treatment is performed at 200 ° C. for 20 hours to obtain an average particle size. An aromatic polyimide powder having a diameter of 30 μm was obtained.

On the other hand, as the aluminum powder, aluminum powder AC-2500 (average particle size 30 μm) manufactured by Toyo Aluminum Co., Ltd. was used.

Next, the aromatic polyimide powder and the aluminum powder thus obtained were mixed in a mixing ratio of only the aromatic polyimide powder, and the aromatic polyimide powder / aluminum powder = 80/20. 60/40, 40/6
0, 20/80, 320 mg of each powder containing only aluminum powder (ratio is weight ratio) was prepared. This mixed powder was mixed prior to being charged into a graphite mold until it became sufficiently uniform.

Next, these powders were molded by a discharge plasma sintering method. Specifically, the powder is charged in the above order into a cylindrical graphite mold having an inner diameter of 2 cm, and a few M is applied so that the surface becomes flat each time each single powder or mixed powder is charged.
A light pressure of Pa was applied. Then, after adding all the components, pressurizing at 50 MPa, and then setting the molding atmosphere at about 5 Pa.
The pressure was reduced to 5 V and electricity of 400 A was applied to carry out spark plasma sintering. In the temperature raising step at this time, first, the temperature is raised from room temperature to 400 ° C. in 6 minutes, further raised to 420 ° C. in 2 minutes, and held at 420 ° C. for 10 minutes.
It was returned to room temperature for about 30 minutes. Then, the functionally graded material which was sintered and integrated was taken out from the mold.

When the cross-section of the functionally graded material obtained as described above was observed with a microscope, it was confirmed that the aromatic polyimide layer, the aluminum layer, and each mixed layer of both were in a precise molding state. In addition, this molded body is 400
After heating at ℃ for 30 seconds, it was rapidly cooled to room temperature, but the shape did not change.

[0044]

COMPARATIVE EXAMPLE 1 Using the same aluminum powder and aromatic polyimide powder as in the above example, a certain amount of aluminum powder was placed in a mold, light pressure was applied to flatten the surface, and The same amount of aromatic polyimide powder was added. Then, molding was performed in the same manner as in the example.

With respect to the obtained molded body, as in the examples.
Microscopic observation of the cross section revealed that it had a dense structure. However, similarly, when the molded body was heated at 400 ° C. for 30 seconds and then rapidly cooled to room temperature, it easily separated at the interface between both components.

[0046]

[Comparative Example 2] Similar to the above-described example, aluminum powder and aromatic polyimide powder were used, and a single powder and a mixed powder were put into a mold under the same conditions. However, a metal mold was used as the mold without using a graphite mold, the pressure was increased to 200 MPa, and the plasma sintering method was not used, that is, no current was applied, and other conditions were the same as in the example. I went. However, the obtained molded body had poor denseness and became brittle.

[0047]

[Comparative Example 3] Molding was carried out in the same manner as in the above Example except that polytetrafluoroethylene powder was used instead of the aromatic polyimide powder. As a result, the resin flowed out in the temperature raising step, and a molded body could not be obtained.

[0048]

EFFECTS OF THE INVENTION In the functionally graded material and the method for producing the same according to the present invention, by using a non-thermoplastic polymer material, both the sintering temperature and the pressure can be set higher than when a thermoplastic resin is used. Therefore, it is possible to use a metal having a high sintering temperature, which cannot be used in the conventional polymer / metal-based functionally gradient material. Therefore, by using a metal having a high sintering temperature and using a non-thermoplastic polymer material having high heat resistance and forming a functionally gradient material composed of both components, a molded article with higher functionality can be obtained. In addition, by using the discharge plasma sintering method for sintering, it has become possible to precisely mold a functionally graded material of a non-thermoplastic polymer material and a metal, which has not been considered in the past.

According to the present invention, in many applications such as corrosion resistant heat exchangers, wear resistant bearings, electrode integrated insulators, etc.
The degree of freedom in material design has increased dramatically, and wide application is expected in fields such as aerospace, chemical industry, mechanical industry, electrical and electronic equipment, nuclear power peripheral equipment, research and experiment it can. Further, by using the polyimide resin powder particles having radiation resistance, it can be used for devices requiring radiation resistance.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a component ratio of a functionally gradient material.

FIG. 2 is a diagram showing another configuration example of the component ratio of the functionally graded material.

FIG. 3 is a diagram showing still another configuration example of the component ratio of the functionally gradient material.

FIG. 4 is a diagram showing still another configuration example of the component ratio of the functionally gradient material.

FIG. 5 is a diagram showing still another configuration example of the component ratio of the functionally gradient material.

FIG. 6 is an explanatory diagram showing an example of a discharge plasma sintering apparatus.

FIG. 7 is a cross-sectional explanatory view showing an example of a graphite heating body.

FIG. 8 is a cross-sectional explanatory view showing another example of the graphite heating body.

FIG. 9 is an explanatory diagram showing an example of an apparatus for producing a functionally gradient material in which the mixing ratio of two components is continuously changed.

[Explanation of symbols]

 22, 26, 28: Mold 24: Mixed powder

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Claims (8)

[Claims] 1. A polymer material having no thermoplasticity and a metal, and having at least a layer composed only of metal, a layer containing both metal and polymer material, and a layer composed only of polymer material. Functionally graded material to be. 2. A component ratio of the metal and the polymer material is continuous between the layer composed of the polymer material having no thermoplasticity and the metal, and the layer composed of the metal only and the layer composed of the polymer material only. Alternatively, a functionally gradient material having an intermediate layer that changes stepwise. 3. The metal has a sintering temperature not higher than about 100 ° C. above the thermal decomposition temperature of the polymeric material, more preferably below the thermal decomposition temperature of the polymeric material. The functionally graded material according to claim 1 or 2. 4. The functionally graded material according to claim 1, wherein the metal is copper or aluminum. 5. The functionally gradient material according to claim 1, wherein the polymer material having no thermoplasticity is a non-thermoplastic polyimide. 6. A powdery material of a polymeric material having no thermoplasticity and a powdery material of a metal are mixed at different ratios, and the ratio is changed continuously or stepwise, and after filling the mold, A method for producing a functionally graded material, which comprises molding by a spark plasma sintering method. 7. The method for producing a functionally graded material according to claim 6, wherein the powdery particles of the polymer material and the powdery particles of the metal are filled in the mold while being diffused by a centrifugal separation method. . 8. The method for producing a functionally graded material according to claim 6, wherein the polymer material powder and the metal powder are filled in a mold while vibrating.