JP2001115224A - Orientation gradient type functionally gradient material and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an orientation gradient type functionally gradient material in which the volume fraction and orientation of plate-like reinforcement-phase grains in a matrix are gradiently changed simultaneously by using a composite material having plate-like reinforcement-phase grains and applying centrifugal force during melting and solidification and to obtain a composite material whose desired part is reinforced by the desired amount in the desired direction. SOLUTION: Although plate-like reinforcement-phase grains receive moment during the application of centrifugal force and are oriented in such a way that the plate surface normal of the plate-like reinforcement-phase grains becomes parallel to the direction of centrifugal force, the moment differs according to the position of a ring. By using the above phenomenon, a composite material having the plate-like reinforcement-phase grains is used and centrifugal force is applied during melting and solidification. By this method, the orientation gradient type functionally gradient material in which the volume fraction and orientation of the plate-like reinforcement-phase grains in the matrix are gradiently changed simultaneously can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a functionally graded material characterized in that the volume fraction and the degree of orientation of the plate-like reinforcing phase particles in the matrix of the composite material are simultaneously gradiently changed, and a method for producing the same. About.

[0002]

2. Description of the Related Art Functionally graded materials are intended to actively change the composition, structure and other functions intentionally in accordance with the use conditions in the design stage of the material, thereby aggressively generating the thermal stress and other functions. This is a new material design concept that is controlled in a controlled manner. In order to manufacture a functionally gradient material, a technology that can freely control the composition distribution and the structure according to the material design is required. Conventional manufacturing technologies for functionally graded materials include chemical vapor deposition,
There are a physical vapor deposition method, a particle arrangement method, a particle injection method, a thin film lamination method, a plasma twin torch spraying method, a self-heating reaction method (combustion synthesis method), and the like.

[0003] However, these manufacturing methods apply relatively new technology, and have the disadvantage that the manufacturing equipment is expensive, and the manufacturing cost is also increased as a result. Further, there is a disadvantage that it is difficult to manufacture a large-sized product.

On the other hand, according to the centrifugal force method, a large-sized product can be manufactured at low manufacturing cost with inexpensive manufacturing equipment. Here, the centrifugal force method applies a centrifugal force to a molten metal containing ceramics or second phase particles, and uses a moving speed difference mainly caused by a difference in centrifugal force caused by a density difference between the molten metal and the dispersed particles. The method for producing a functionally graded material in which the composition gradient is controlled by using

[0005]

SUMMARY OF THE INVENTION The mechanical properties of plate-like particle-reinforced or fiber-reinforced composite materials depend not only on the volume fraction of the reinforcing phase in the matrix but also on the degree of orientation. Therefore,
In functionally graded materials, not only simply changing the volume fraction of the reinforcing phase in a gradient manner, but also changing the degree of orientation in a gradient manner depending on the position, it is possible to obtain a functionally graded material having performance that meets the required design conditions. Can be provided.

The present invention has been made in view of such circumstances, and has as its object to manufacture a functionally graded material having performance meeting various conditions required by design, and is relatively easy to manufacture, has a low manufacturing cost, and has a large size. Provided is a method for producing a functionally graded material in which the volume fraction and the degree of orientation of plate-like reinforcing phase particles in a matrix phase change simultaneously and gradient utilizing a centrifugal force method capable of producing a product having a shape.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a volume fraction of plate-like reinforcing phase particles in a material is obtained by applying a centrifugal force to a liquid phase matrix in which plate-like reinforcing phase particles are dispersed. And a functional material in which the and the degree of orientation are simultaneously and obliquely distributed.

Further, centrifugal force is applied by dispersing the plate-like reinforcing phase particles in a liquid-phase parent phase and injecting the dispersed particles into a rotating mold, whereby the parent phase and the plate-like reinforcing phase particles are mixed. By controlling the movement of the particles by the difference in centrifugal force caused by the density difference between them, and simultaneously controlling the moment applied to the plate-like reinforcing phase particles, the volume fraction and orientation degree of the plate-like reinforcing phase particles in the material Is to obtain a functional material which is simultaneously and obliquely distributed.

Here, the plate-shaped reinforcing phase particles are subjected to centrifugal force application,
The plate-like reinforcing phase particles are oriented so that the normal direction of the plate surface is parallel to the direction of the centrifugal force because a moment is received in the parent phase in the liquid state. At this time, if the difference in the centrifugal force between the inner circumference and the outer circumference of the ring and the difference in the angular velocity of the molten metal between the inner circumference and the outer circumference of the ring are used, the degree of orientation of the plate-like reinforcing phase particles changes depending on the position. Thus, a functionally graded material having an orientation degree gradient type is obtained.

[0010]

Embodiments of the present invention will be specifically described below with reference to the drawings. The base material of the composite material used in the present invention is a commercially available Al-5 mass% Ti alloy.
In this base material, Ti exists as plate-like Al ₃ Ti intermetallic compound particles. Here, the Al ₃ Ti intermetallic compound is a new material that is expected as a next-generation heat-resistant structural material because of its light weight, high hardness, and excellent corrosion resistance. Further, since the melting point is as high as 1342 ° C., it is possible to realize the condition that the plate-like reinforcing phase particles exist as a solid phase even when the parent phase is dissolved.

The material was dissolved by heating to a temperature range in which the parent phase was in the liquid phase and the plate-like reinforcing phase particles were in the solid phase.
Casting was performed under the application of centrifugal force to produce a plate-like particle-reinforced functionally graded material. Casting under the application of centrifugal force was performed by the centrifugal casting device shown in FIG.

Here, the centrifugal casting device will be described. First,
Al-5 mass in the crucible installed in the melting furnace
% Ti alloy is added and melted. A hole is made in the bottom of this crucible, which is plugged with a ceramic rod before injection. Under specified casting conditions, by removing this plug, the molten metal can be injected directly from the bottom of the crucible through the gate to the rotating mold. Here, the mold is heated by a mold heating furnace and further rotated by a motor connected by a shaft and a belt pulley. Application is possible. In addition, since the mold heating furnace is mounted on a cart and can move on rails, the cooling rate can be controlled after pouring the molten metal.

At this time, a difference in centrifugal force occurs due to a difference in density between the matrix phase and the plate-like reinforcing phase particles. Then, under the application of the centrifugal force, the plate-like reinforced phase particles receive a moment, and are oriented such that the plate surface normal direction of the plate-shaped reinforced phase particles is parallel to the centrifugal force direction.

Next, FIG. 2 is a schematic view of the manufactured Al / Al ₃ Ti functionally gradient material ring. The plate-like Al ₃ Ti intermetallic compound particles were oriented such that the plate surface normal direction of the plate-like reinforcing phase particles was parallel to the centrifugal force direction. The structure of this ring was observed from the rotation axis direction.

Plate-like Al ₃ in the manufactured functionally graded material
FIG. 3 shows changes in the volume fraction of the Ti intermetallic compound particles depending on the position. Here, the horizontal axis indicates the standardized ring position, where 0.0 is the innermost circumference of the ring and 1.0 is the outermost circumference of the ring. These materials were produced under conditions where the gravity multiple was G = 10, 30 and 50. Here, the gravity multiple is obtained by normalizing the centrifugal force by gravity.

As can be seen from FIG. 3, the volume fraction of the plate-like Al ₃ Ti intermetallic compound particles was high outside the ring, and gradually decreased toward the inner periphery of the ring. This is because the plate-like Al ₃ Ti intermetallic compound particles have a higher density than that of the molten aluminum Al, and thus the plate-like Al ₃ Ti intermetallic compound particles have moved to the outside of the ring under the application of centrifugal force. In addition, the degree of the gradient of the volume fraction increased as the multiple of gravity increased. As described above, the volume fraction of the plate-like Al ₃ Ti intermetallic compound particles is gently inclined, and the functionally gradient material can be manufactured by the centrifugal force method even if the shape of the reinforcing phase is plate-like.

Next, attention is paid to the degree of orientation of the particles. Therefore, the orientation angle of the plate-like reinforcing phase particles is defined as shown in FIG. That is, the direction of the centrifugal force was taken as the reference axis, and the angle between the normal direction of the plate surface of the plate-shaped reinforcing phase particles and the reference axis was defined as the orientation angle.

At each position of the manufactured sample ring, the orientation angle of each plate-like Al ₃ Ti intermetallic compound particle was measured. FIG. 5 shows an example in which the relationship between the orientation angle and the relative frequency is arranged. Here, the manufacturing condition of the sample ring is G = 30.
, And the value written in the upper left of the figure is the normalized position of the ring.

When the normalized position was 1.0 to 0.9, that is, at the outer periphery of the ring, the frequency of the plate-like reinforcing phase particles having an orientation angle of 0 ° was high. That is, the plate-like Al ₃ Ti intermetallic compound particles were oriented such that the normal direction of the plate surface of the plate-like reinforcing phase particles was parallel to the centrifugal force direction at the outer periphery of the ring.

On the other hand, when the standardized position at the center of the ring is 0.5 to 0.4, the tendency is weakened. When the normalized position, which is the inner peripheral portion of the ring, was 0.1 to 0.0, no orientation was recognized, and the plate-like reinforcing phase particles were present at equal frequencies in all directions. As described above, it has been found that the degree of orientation varies depending on the position in the manufactured ring.

Next, in order to quantitatively evaluate these aspects of the orientation, the orientation was evaluated using the Hermann degree of orientation. Here, the Hermann orientation degree is a two-dimensional orientation degree evaluation method most widely used at present. The Hermann orientation degree is defined by fp = [2 <cos ² φ> −1]. Here, φ is the orientation angle, and <cos ² φ> is the average of the triangular method. When all the plate-like reinforcing phase particles are oriented, the value of the degree of orientation fp of Herman is 1 and when all the plate-like reinforcing phase particles are present in a completely disordered state,
The value of the Hermann orientation fp is 0.

FIG. 6 shows the inclination with respect to the position of the orientation degree of Hermann in the functionally graded material. Outside the ring, the degree of orientation of the plate-like Al ₃ Ti intermetallic compound particles was high, and the degree of orientation gradually decreased toward the inner periphery of the ring. Also, the degree of inclination of the degree of orientation was increased as the gravity multiple was increased. As described above, the degree of orientation of the plate-like Al ₃ Ti intermetallic compound particles is gently inclined, and it becomes possible to produce an orientation-graded functionally graded material by the centrifugal force method.

The mechanical properties of the plate-like particle-reinforced composite material depend not only on the volume fraction of the reinforcing phase in the matrix but also on the degree of orientation. In addition, anisotropy of mechanical properties also appears depending on the orientation. Therefore, it is expected that not only the mechanical properties but also the anisotropy of the obtained gradient-graded functionally graded material are inclined. To confirm this,
A pin-on-disk wear test was performed.

FIG. 7 shows the results of the wear test of the functionally graded material and pure aluminum manufactured under the condition of G = 30. The horizontal axis is the wear distance, and the vertical axis is the wear amount. The wear of all the functionally graded materials was smaller than that of the pure aluminum test piece prepared by the same method, and the wear of the ring outside where the amount of plate-like Al ₃ Ti intermetallic compound particles was large was smaller than the amount of particle. It can be seen that the plate-like Al ₃ Ti intermetallic compound particles are effectively working as a reinforcing phase, being smaller than the inside of the ring, which is less.

At the outer periphery of the ring, anisotropy of the wear characteristics appeared depending on the direction. This is due to the orientation of the plate-like Al ₃ Ti intermetallic compound particles, and it has been found that the wear characteristics of the plate-like reinforcing phase particles in the direction in which the particles are difficult to be divided are superior to those in the direction in which the particles are easily divided. Was.

As described above, the functionally gradient graded functional material exhibits not only excellent mechanical properties, but also mechanical properties and its anisotropy change depending on the position. The required amount of reinforcement can be provided, and the mechanical properties required for material design can be provided.

[0027]

As described above, according to the present invention, it is possible to produce a functional material in which the volume fraction of the plate-like reinforcing phase particles in the composite material is inclinedly changed for each position. Became possible. Further, it has become possible to produce a functionally graded material (claim 2) in which plate-like reinforcing phase particles are oriented in a composite material.

Further, in the composite material, the volume fraction of the plate-like reinforcing phase particles changes at each position in an inclined manner, and at the same time, the orientation degree of the plate-like reinforcing phase particles changes at each position in an inclined manner. It has become possible to produce a functional material (claim 3). Further, by changing the degree of orientation, a functionally graded material having a gradient of anisotropy in mechanical properties and physical properties (claim 4) is dissolved in a composite material having plate-like reinforcing phase particles, and centrifugal force is reduced. It is possible to manufacture by applying the voltage (claim 6).

In addition, in the composite material, the mother phase is a liquid phase,
By applying a centrifugal force in a temperature range in which the plate-like reinforcing phase particles exist as a solid phase, it is possible to produce a functionally graded material in which the volume fraction and the degree of orientation of the plate-like reinforcing phase particles simultaneously change in a gradient manner. It has become possible (claim 7). Further, in a composite material in which plate-like Al ₃ Ti intermetallic compound particles are dispersed in an aluminum matrix, by applying a centrifugal force, the volume fraction and the degree of orientation of the plate-like reinforcing phase particles simultaneously and obliquely change. It has become possible to produce a functionally gradient material (claim 8).

The graded orientation type functionally graded material not only exhibits excellent mechanical properties but also changes mechanical properties and its anisotropy depending on the position. Can provide a higher grade functionally graded material. In addition, since the method for producing a functionally graded material according to the present invention is a method for producing a functionally graded material using a simple apparatus and applying a simple principle, large-sized materials can be produced at low cost and with high productivity.

The concept of eco-material was proposed for the first time in Japan as a new material for solving global environmental problems and enabling sustainable development of society and economy. Eco-materials is a new concept that aims to achieve both material performance and environmental harmony. The basic philosophy of revolutionarily improving environmental efficiency by simultaneously pursuing extreme material performance and low environmental impact is being formed worldwide as the undercurrent of technology,
Eco-materials and eco-design (environmentally friendly design) have become key concepts in technology development.

The representative of the eco-material is a material that is easy to recycle. In addition, from the viewpoint of effective use of resources, it is desirable to obtain the required properties in the required directions in the required directions, instead of uniformly seeking the characteristics of the entire product.

Generally, functionally graded materials are classified into the category of composite materials, and are often difficult to recycle. However, since the functionally gradient material obtained in the present invention easily returns to the state before the functional gradient is added by re-dissolution as shown in FIG. 8, it is considered that the material is easily recyclable.
Further, since the functional material of the present invention has a gradient of volume fraction, a gradient of degree of orientation and anisotropy due to orientation, the present invention provides a functionally graded material that obtains necessary properties in necessary directions in necessary directions. obtain.

As described above, the gradient-graded material having a high degree of orientation has high performance, can be mass-produced, can be manufactured in large products, can save resources, and can be easily recycled. Industrial applications are conceivable in various fields. For example, it can be applied to a part used under wear conditions such as an engine.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an embodiment of a centrifugal casting apparatus for producing a functionally graded material with a gradient degree of orientation according to the present invention.

FIG. 2 is a schematic diagram showing the orientation of plate-like Al ₃ Ti intermetallic compound particles in an Al / Al ₃ Ti functionally gradient material ring.

FIG. 3 is a view showing a volume fraction distribution of plate-like reinforcing phase particles in a functionally gradient material.

FIG. 4 is a view showing a definition of an orientation angle of plate-like reinforcing phase particles.

FIG. 5 is a diagram showing an orientation degree distribution in a functionally graded material.

FIG. 6 is a diagram showing an inclination with respect to the position of the orientation degree of Hermann in a functionally graded material.

FIG. 7 is a view showing the results of a wear test of the manufactured functionally graded material and pure aluminum.

FIG. 8 is a flowchart showing a method of recycling the manufactured functionally graded material.

[Explanation of symbols]

1 ... melting furnace 2 ... crucible 3 ... melt 4 ... ceramic plug 5 ... sprue 6 ... die 7 ... die heating furnace 8 ... motor 9 ... belt pulley 10 ... shaft 11 ... carriage 12 ... rails 13 ... Al / _Al 3 Ti Functionally graded material ring 14 Plate Al ₃ Ti intermetallic compound particles 15 Rotation axis 16 Observation surface 17 Plate reinforcing phase particles 18 Orientation angle 19 Centrifugal direction 20 Ingot 21 Centrifugal casting device 22 Orientation Degree-graded functionally graded material ring 23 ... graded degree-graded functionally graded material

Claims (8)

[Claims] 1. A functional material characterized in that the volume fraction of the plate-like reinforcing phase particles in the composite material changes obliquely from position to position. 2. The functionally gradient material according to claim 1, wherein the plate-like reinforcing phase particles are oriented in the composite material. 3. The composite material in which the volume fraction of the plate-like reinforcing phase particles is inclinedly changed at each position, and at the same time, the degree of orientation of the plate-shaped reinforcing phase particles is inclinedly changed at each position. The functionally gradient material according to claim 1, wherein: 4. The functionally gradient material according to claim 1, wherein the functionally graded material has an anisotropic gradient in mechanical properties and physical properties by changing the degree of orientation. 5. The method according to claim 1, wherein the volume fraction and the degree of orientation of the plate-like reinforcing phase particles are simultaneously and obliquely changed by utilizing the composite material having the plate-like reinforcing phase particles.
A method for producing the functionally gradient material according to the above. 6. The volume fraction and the degree of orientation of the plate-like reinforcing phase particles are simultaneously and obliquely changed by dissolving the composite material having the plate-like reinforcing phase particles and applying a centrifugal force. The method for producing a functionally gradient material according to claim 5. 7. The functionally graded material according to claim 5, wherein a centrifugal force is applied in a temperature range in which the matrix is in a liquid phase and the plate-like reinforcing phase particles are in a solid phase. Production method. 8. The method for producing a functionally gradient material according to claim 5, wherein a centrifugal force is applied to a composite material in which plate-like Al ₃ Ti intermetallic compound particles are dispersed in an aluminum matrix.