JP2816439B2 - Manufacturing method of functionally graded material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Industrial Application Field The present invention relates to a functionally gradient material (Functionally Gradient Mate).
rial).

b. Prior Art In recent years, several space flights have been made by space shuttles, for example, space shuttles. Since such a flying object is exposed to light heat and high pressure during flight, a material having both functions of heat resistance and mechanical strength is required. In reality, it is thought that a combination of a heat-resistant material such as silica tile and a homogeneous material having specific functions such as a metal material having high mechanical strength is used in combination.

The present invention relates to a so-called functionally graded material, which is different from such a homogeneous material and has two different functions, that is, a material having different functions in an inclined state.

Conventional technologies relating to such functionally graded materials include a vapor phase method (PVD, CVD), a particle arrangement method, a plasma spray lamination method,
There is a production method by a self-heating reaction method or the like. In addition, as a recent development technology of a method for manufacturing a functionally graded material, Japanese Patent Application No.
No. 297042 and Japanese Patent Application No. 61-187370.

c. Problems to be Solved by the Invention Among the above methods, the vapor phase method is extremely slow at a film forming rate of about 1 mm / h, and in particular, the PVD method (physical method) is a method of synthesizing a simple substance-based film. It is limited to only.

In addition, in the particle arrangement method, it is difficult to arrange the raw material powder by arbitrarily changing the composition, and it is necessary to develop an easily sinterable ceramic powder and a new sintering technique.

In the plasma spray lamination method, it is difficult to spray different materials at exactly the same position, and there is a disadvantage that the composition of the formed layer is inevitable.

Further, in the self-exothermic reaction method, for example, as shown in FIG. 3, a raw material powder is charged into an apparatus a in a stepwise manner like b, c, d, e, etc., and then ignited at a point p to cause a self-exothermic reaction. Pressure synthesis is performed, and it is not possible to manufacture a dense, complicated, or large-sized product by such a method.

An object of the present invention is to provide a method for producing a functionally graded material capable of producing a large-sized, complicated-shaped one by simultaneously performing joining and forming by utilizing superplastic joining instead of the conventional technique as described above. I do.

d. Means for Solving the Problems According to the above object, the present invention provides a method of superplasticizing at a predetermined temperature by sintering a plurality of materials having a mixed composition of fine-grained ceramic and fine-grained metal. The above-mentioned problem was solved by preparing a plurality of sintered bodies exhibiting the above-mentioned, stacking these sintered bodies in the order of the gradient of the mixed composition, heating and pressurizing to a superplastic expression temperature range, and joining and molding integrally. .

 Hereinafter, the present invention will be described in detail.

The present invention uses a ceramic having a grain size of about 1 μm or less, or a material having a two-phase mixed structure of fine crystal grains composed of a metal having a grain size of about 10 μm or less. Then, materials having these compositions inclined continuously or discontinuously are set, and these are used as intermediate layers or layered in the order of inclination, and then pressurized at superplastic temperature and joined to form a matrix. A functionally graded material having the same strength as the material is obtained.

That is, a material in which superplasticity appears at a predetermined temperature, for example, a partially stabilized zirconia obtained by dissolving 3 mol% of yttria and alumina, and a composition having a gradient thereof are used as an intermediate layer for the zirconia and alumina.
Alternatively, a material having the functions of both materials is manufactured by interposing a plurality of layers and pressing them at a superplastic temperature.

As a result, the function of the material is gradually inclined from one side to the other side, and an integrated functionally graded material having different functions on both sides is obtained.

e. Example As shown in FIG. 1, superplastic materials A to F are stacked in the order shown in the drawing. Here Of each composition.

The materials A, B, C, D and E are manufactured by sintering at 1500 ° C. for 1 hour in a hot isostatic press (HIP). Material F is 130
It was sintered at 0 ° C for 1 hour under normal pressure. These are superplastic materials each having a particle size of 1 μm or less and exhibiting an elongation of 100% or more at high temperatures.

These materials A to F are ground to a surface roughness Rmax of about 2 μm with a diamond wheel and the contact surfaces of the materials A to F, layered in the order shown in FIG. 1, and heated and pressed under joining conditions of about 1500 ° C. and 12.5 MPa. I got one piece of material. Approximately 50 kg of material obtained
/ mm ² bending strength was obtained.

FIG. 2 shows another embodiment, in which a number of superplastic materials having the above-mentioned composition formed in a mountain shape are superimposed on each other as shown in FIG. An integrated product having the shape shown in FIG.

f. Effect of the Invention By applying the method for producing a functionally graded material according to the present invention to a superplastic ceramic sintered body, it becomes possible to join ceramic sintered bodies, which was not possible conventionally, and the joining strength Also, the strength of the joined body itself is very large. Also, if the joining surface of the ceramic sintered body is polished,
The thickness of each ceramic sintered body becomes constant, and the joining surface becomes flat. In this state, if the respective ceramic sintered bodies are layered and joined, a functionally graded material with good dimensional accuracy can be obtained. Further, since the pressing and heating of the ceramic sintered body are performed simultaneously, the processing time can be reduced by omitting the steps, and the cost can be reduced.
The superplastic joining allows the joining interface to have the same strength as that of the base material, so that it can be used as a structural part. According to the present invention, functionally graded materials having large and complex shapes can be manufactured, the manufacturing cost is relatively low, and heat resistance, abrasion resistance, and corrosion resistance are required in the mechanical field. It can be widely used in the nuclear field where radioactivity is required, the electronics and optoelectronic fields where electrical and optical properties are required, and the medical field where biocompatibility is required.

[Brief description of the drawings]

FIG. 1 is a view for explaining an embodiment of the method for producing a functionally gradient material according to the present invention, FIGS. 2 (a) and 2 (b) are explanatory views of another embodiment, and FIG. It is explanatory drawing which shows an example.

Claims (1)

(57) [Claims] 1. A plurality of sintered bodies exhibiting superplasticity at a predetermined temperature are produced by sintering a plurality of materials having a mixed composition of fine-grained ceramics and fine-grained metal incline. A method for producing a functionally graded material, comprising: laminating sintered bodies in the order of the gradient of the mixed composition, heating and pressing to a superplasticity temperature range, and joining and forming integrally.