JPH0655515A - Manufacture of fiber reinforced ceramics and manufacturing equipment - Google Patents

Abstract

PURPOSE:To provide the manufacturing method and device of fiber reinforced ceramics, with which the anisotropies of bending strength and of fracture toughness are improved while contriving to densify compact so as to allow increase its use for machine part and structural material. CONSTITUTION:When ceramics compact 10 is produced by extruding mixture 9, which is prepared by mixing ceramics powder 7 and inorganic fibers 8 and, after that, filled in a cylinder 2, under pressure through the extrusion nozzle 4 of the cylinder 2, axially helically extending projected strips 5 are protrusively provided on the inner peripheral wall 4a of the nozzle 4 so as to give twisting to the mixture 9 by passing through the nozzle 4. Thus, compact 10, in which inorganic fibers 6 are helically orientated, is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a fiber-reinforced ceramics molded body in which an inorganic fiber is mixed in a ceramics matrix. The present invention relates to a manufacturing method and an apparatus for improving the anisotropy of toughness and expanding the application.

[0002]

2. Description of the Related Art Fiber-reinforced ceramics prepared by mixing inorganic fibers into ceramics have excellent mechanical properties such as strength, toughness, and wear resistance, and are suitable for various mechanical parts and structural materials. Is being watched as. As a method for producing this fiber-reinforced ceramics, there has been a conventional method in which inorganic fibers are mixed into a ceramic material to form a kneaded product, and the kneaded product is molded by a die, CIP, extrusion or the like. However, since the inorganic fibers are randomly arranged in the molded body thus obtained, the shrinkage of the ceramics is hindered during sintering, and as a result, it is difficult to densify the sintered body. For this reason, the blending amount of the inorganic fiber is limited to a small amount. In order to improve the shrinkability of such ceramics, conventionally, there is a method of obtaining a dense body by sintering a molded body under high temperature and high pressure by HIP, hot pressing, or the like. Further, in JP-A-62-270470 and JP-A-2-263768, inorganic fibers are arranged in one direction to improve sinterability,
A method and an apparatus have been proposed in which the density of the inorganic fibers can be increased while increasing the densification.
As shown in FIG. 2, a kneaded material 13 of a ceramic material 11 and an inorganic fiber 12 is filled in a cylinder 14, and the kneaded material 13 is pressed by a pressure punch 15 while being ejected from an extrusion nozzle 16 of the cylinder 14. It is configured to extrude. The fibers 12 arranged randomly at the time of the extrusion are gradually oriented in the extrusion direction, and as a result, the small-diameter intermediate molded body 1 in which the inorganic fibers 12 are arranged in one direction.
7 is obtained. After that, the intermediate molded body 17 is laminated,
After bundling, pressure molding is performed with a mold, CIP, etc., thereby forming an integrally molded body of a predetermined size and shape, and thereafter, high temperature and high pressure sintering is performed with HIP, hot pressing, etc. . There is also a method of obtaining a dense body by rolling with a roll or the like.

[0003]

However, although the manufacturing methods according to the above-mentioned conventional publications are effective for obtaining a dense molded body, since the inorganic fibers have a structure in which they are arranged in the axial direction, the bending strength, There is a problem that anisotropy occurs in fracture toughness and the like, and as a result, its application to mechanical parts and structural materials is limited.

The object of the present invention is to manufacture a fiber-reinforced ceramics which can improve mechanical properties by improving anisotropy with respect to bending strength and fracture toughness while densifying a molded body, and eventually expanding its application. A method and apparatus are provided.

[0005]

[Means for Solving the Problems] The inventors of the present invention have conducted a study to improve the anisotropy while densifying the molded body. As a result, attention has been paid to the fact that the inorganic fibers are oriented in the extrusion direction during extrusion molding. It was found that the anisotropy can be improved by orienting this fiber spirally with respect to the extrusion direction, and the present invention has been accomplished.

Therefore, the invention of claim 1 fills the kneaded material in which the ceramic powder is mixed with the inorganic fiber into the cylinder, and extrudes from the extrusion nozzle of the cylinder while pressurizing the kneaded material to form a ceramic molded body. In the method for producing fiber-reinforced ceramics, the kneaded product is extruded while being twisted, thereby obtaining a molded product in which the inorganic fibers are arranged in one direction and in a spiral shape. . The invention of claim 2 is an apparatus for carrying out the above method, which is characterized in that a spiral ridge is formed on the inner surface of the extrusion nozzle.

Here, the ceramic powder is Al
Oxides, nitrides, and carbides such as ₂ O ₃ , ZrO ₂ , Si ₃ N ₄ , and SiC can be adopted. Further, short fiber oxides, nitrides, and carbides can be adopted as the above-mentioned inorganic fibers, and the compounding amount thereof is preferably in the range of 10 to 20 wt%.

[0008]

According to the method for producing a fiber-reinforced ceramics of the present invention, since the kneaded product is twisted by the extrusion nozzle, the randomly arranged inorganic fibers are unidirectional when passing through the extrusion nozzle. In addition, they are arranged in a spiral shape at a predetermined angle, whereby a compact compact having no anisotropy can be manufactured. As a result, fiber-reinforced ceramics having excellent mechanical properties such as bending strength and fracture toughness can be obtained, and the application to machine parts and structural materials can be expanded.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining a method for manufacturing fiber-reinforced ceramics according to an embodiment of the present invention. In the figure, reference numeral 1 is an extruder used for carrying out the method of this embodiment. This device 1 is configured by inserting a pressure punch 3 into a cylinder 2 so as to be able to move back and forth, and connecting and forming an extrusion nozzle 4 at the tip of the cylinder 2.

On the inner peripheral wall 4a of the extrusion nozzle 4, a plurality of projections 5 extending in a spiral shape in the axial direction are provided in a protruding manner, and the inclination angle of each projection 5 is set to about 45 degrees. There is. Thereby, the kneaded product is twisted, or twisted while rotating the kneaded product.

Next, a method of manufacturing the fiber reinforced ceramics by the above-mentioned extrusion device 1 will be described. First, a short fiber SiC whisker 8 is mixed with alumina powder 7 in the range of 10 to 20 wt%, and a binder and a plasticizer are added thereto to form a kneaded material 9 having a predetermined hardness. The kneaded material 9 is re-kneaded in a vacuum or reduced pressure vessel to be sufficiently deaerated. As a result, a kneaded material 9 in which SiC whiskers 8 are randomly arranged in the alumina powder 7 serving as a matrix is formed.

Next, the kneaded material 9 is filled in the cylinder 2, and in this state, the pressure punch 3 is lowered to pressurize the kneaded material 9. Then, the kneaded material 9 is extruded in a twisted state while rotating along each protrusion 5 of the extrusion nozzle 4. As a result, the ceramic molded body 10 in which the SiC whiskers 8 are inclined in the extrusion direction and uniformly arranged in a spiral shape is obtained. Here, on the outer peripheral surface of the molded body 10, a groove-shaped concave portion is formed by the protrusion 5, and the concave portion is removed by scraping off the surface of the molded body 10.

The molded body 10 thus obtained is heated to 500 ° C. in an inert gas atmosphere to remove the binder and the like, and subsequently heated to about 1800 ° C. and heated at atmospheric pressure. Tie. As a result, the fiber-reinforced ceramics of this example is manufactured.

As described above, according to this embodiment, since the protrusion 5 extending in a spiral shape is formed on the inner peripheral wall 4a of the extrusion nozzle 4 and the kneaded material 9 is twisted by the protrusion 5, random kneading is performed. The SiC whiskers 8 arranged in the above are spirally arranged at a predetermined angle when being extruded. This makes it possible to obtain a compact compact 10 with little anisotropy, to manufacture fiber-reinforced ceramics having excellent mechanical properties such as bending strength and fracture toughness, and to use it for shaft parts and structural materials. Can be greatly expanded.

Further, since the method of the present embodiment is a method of obtaining a dense compact 10 only by imparting a twist to the kneaded material 9, the shrinkage of the ceramics can be maintained even if the pressureless sintering is performed. It can be improved, and high temperature and high pressure sintering by conventional HIP or hot pressing can be eliminated.

Next, a test carried out to confirm the effect of the manufacturing method according to this embodiment will be described. This test is performed by the manufacturing method of the present embodiment described above, 3 mm × 4 mm ×
A 40 mm 3-point bending test piece was prepared, and the fracture toughness value of this test piece was measured by a bending test at room temperature and by micro-Vickers (load 50 Kg / mm ² ). Further, for comparison, a conventional extrusion apparatus shown in FIG. 2 was used to manufacture a molded body in which SiC whiskers were arranged in a uniaxial direction, and the same measurement was performed. The amount of SiC whiskers in each of the above test pieces was 10
It was set to wt%.

[0017]

[Table 1]

As is clear from Table 1, in the case of a conventional sample in which SiC whiskers are uniaxially arranged (first column).
The bending strength is as high as 80 kg / cm ² and the fracture toughness value is as high as 7.3 MPa m ^{1/2 in the} direction perpendicular to the axis, but 3.5 MPa in the axis direction.
^It is as low as ^1/2, and there is a difference of more than twice, and anisotropy occurs. On the other hand, in the case of the sample of this example which is arranged in a spiral shape (column 2), although the bending strength is slightly low at 73 Kg / cm ² , the fracture toughness value is 6.7 and 5.9 MPa in both the axis-perpendicular direction and the axial direction.
Since it is m ^1/2 , it can be seen that the anisotropy is improved. Further, when the longitudinal cross section of the sample of this example was observed by an optical microscope, it was confirmed that the SiC whiskers were inclined at about 35 to 40 degrees with respect to the extrusion direction. Further, when the relative density of the above-mentioned sample of this example after sintering was measured, it reached 100%, and cracking, peeling, etc. did not occur at all.

[0019]

As described above, according to the method for producing a fiber-reinforced ceramics of the present invention, when the kneaded product is extruded, the twist is imparted to the kneaded product, which allows the inorganic fiber to spiral in one direction. It is possible to form compacts arranged in a shape, and it is possible to manufacture compact compacts that do not have anisotropy with respect to bending strength and fracture toughness. As a result, strength and toughness can be improved. This has the effect of expanding the application to parts and structural materials.

[Brief description of drawings]

FIG. 1 is a diagram showing an extrusion apparatus for carrying out a method for producing fiber-reinforced ceramics according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional extrusion molding method.

[Explanation of symbols]

 2 Cylinder 4 Extrusion Nozzle 7 Alumina Powder (Ceramics Powder) 8 SiC Whisker (Inorganic Fiber) 9 Kneaded Product 10 Molded Product

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Asano 179-1, Kanegasaki Nishioike, Uozumi-cho, Akashi-shi, Hyogo Kobe Steel Works Akashi Plant

Claims (2)

[Claims] 1. A fiber-reinforced ceramics which is prepared by filling a cylinder with a kneaded material obtained by mixing ceramic powder with inorganic fibers, and extruding the kneaded material from an extrusion nozzle of the cylinder while pressurizing the kneaded material to form a ceramic molded body. In the method for producing a fiber-reinforced ceramics, the kneaded product is extruded while being twisted to obtain a molded product in which the inorganic fibers are arranged in one direction and in a spiral shape. . 2. A fiber-reinforced ceramics which is prepared by filling a kneaded material obtained by blending ceramic powder with inorganic fibers into a cylinder and extruding the kneaded material from an extrusion nozzle of the cylinder while pressurizing the kneaded material to form a ceramic molded body. The manufacturing apparatus and the manufacturing apparatus of the fiber-reinforced ceramics, wherein a spiral ridge is formed on the inner surface of the extrusion nozzle.