JPH0655519A - Manufacture of fiber reinforced ceramics and manufacturing equipment - Google Patents

Abstract

PURPOSE:To provide a manufacturing method and device of fiber reinforced ceramics, with which dense and large-diametral compact can be molded and consequently the reliability to its quality can be improved without developing troubles such as the mixing in of foreign matter, exfoliation, crack and the like during production. 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, an intermediate nozzle 5, in which a large number of circular nozzle holes 6, is provided on the upstream of the extrusion nozzle 4 in the cylinder 2. By dividing the mixture 9 into small diametral bars 10a at its passing through the intermediate nozzle 5, the inorganic fibers are uniformly orientated. After that, the resultant bars are extruded through the extrusion nozzle 4 into the form of dense and large-diametral compact 10.

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 ceramic molded body in which an inorganic fiber is mixed in a ceramic matrix, and more specifically, there is a problem that foreign matter is mixed in, peeled off, or cracked during the production. The present invention relates to a manufacturing method and a device capable of forming a dense and large-diameter molded body without causing a crack, and further improving reliability of quality.

[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 conventionally a method in which an inorganic fiber is 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. 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, a method and apparatus for improving sinterability by arranging inorganic fibers in one direction so as to achieve densification Is proposed.

As shown in FIG. 5, a cylinder 1 is made by mixing a kneaded material 13 of a ceramic material 11 and an inorganic fiber 12.
4, and the kneaded material 13 is extruded from the extruding nozzle 16 of the cylinder 14 while pressurizing the kneaded material 13 with the pressure punch 15.

During the extrusion, the randomly arranged fibers 12 are gradually oriented in the extruding direction, whereby a small-diameter intermediate molded body 17 in which the inorganic fibers 12 are arranged in one direction is obtained. Stacking this intermediate molded body 17,
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. .

[0005]

By the way, in the manufacturing method and apparatus according to the above publications, the nozzle diameter is set to a small diameter in order to forcibly orient the inorganic fibers in the extrusion direction. Therefore, the obtained intermediate compact has a small diameter, and in order to obtain a large-diameter compact, it is necessary to stack or bundle the intermediate compact outside the cylinder.
In such a conventional method, since the number of times of handling is increased, foreign substances are easily mixed in each step, and further, when laminated or bundled, peeling or cracking is likely to occur in the molded body, which causes an obstacle to mechanical properties. However, there is a problem in that the reliability of quality is low.

An object of the present invention is to provide a method and an apparatus for producing fiber reinforced ceramics, which can solve the problems such as mixing of foreign matter and peeling during manufacturing while improving the densification of the molded body and improving the reliability of quality. To do.

[0007]

According to a first aspect of the present invention, a kneaded material prepared by mixing ceramic powder with inorganic fibers is filled in a cylinder, and the kneaded material is extruded from an extrusion nozzle of the cylinder while pressurizing the kneaded material. In the method for producing a fiber-reinforced ceramics to form a molded body,
By separating the kneaded product into a plurality of small-diameter rods, the inorganic fibers in the rods are arranged in the axial direction of the rods, and then the rods are formed into one molded body having a circular cross section. It is characterized in that it is adapted to be extruded from the extrusion nozzle while being assembled.

The invention according to claim 2 is an apparatus for carrying out the above manufacturing method, wherein the intermediate nozzle has a plurality of small-diameter circular nozzle holes formed upstream of the extrusion nozzle in the cylinder. And the extrusion nozzle has a circular shape with a diameter smaller than that of the cylinder.

Here, each nozzle hole of the intermediate nozzle is
It is desirable to form a taper shape with a smaller diameter toward the extrusion nozzle. With this structure, the alignment index of the inorganic fibers (longitudinal section 220 / lateral section 220) can be improved.

The above ceramic powder contains Al _{2
O 3, ZrO 2, Si 3} N 4, oxides such as SiC, nitrides, carbides can be employed. Further, the inorganic fiber,
Short fiber oxides, nitrides, and carbides can be used, and the blending amount of these is preferably in the range of 10 to 20 wt%.

[0011]

According to the method and apparatus for producing a fiber-reinforced ceramics of the present invention, since the intermediate nozzle having a plurality of nozzle holes is provided above the extrusion nozzle, the kneaded product passes through the intermediate nozzle and a plurality of fine particles are passed. When separating into the diameter rod body, the randomly arranged inorganic fibers are oriented in the extrusion direction,
The small-diameter rod bodies in which the fibers are uniformly arranged in one direction are extruded from the extrusion nozzle while being collected into one large-diameter formed body in the cylinder. Therefore, a dense and large-diameter molded body can be manufactured. As a result, it is possible to eliminate the step of stacking or bundling outside the cylinder after extruding the intermediate molded body as in the prior art publication, so that it is possible to solve the problem of foreign matter mixing, peeling and cracking, and eventually the mechanical properties. It is possible to improve the reliability of the quality by avoiding the deterioration.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are views for explaining a method and an apparatus for producing fiber reinforced ceramics according to an embodiment of the inventions of claims 1 and 2. In the figure, reference numeral 1 is an extrusion apparatus for carrying out the method of this embodiment. This device 1 has a cylinder 2
A pressure punch 3 is inserted in the cylinder so as to be able to move forward and backward, and an extrusion nozzle 4 is connected and formed at the tip of the cylinder 2. The inner diameter of the extrusion nozzle 4 is the same as that of the cylinder 2
Is formed to have a smaller diameter than the inner diameter of.

An intermediate nozzle 5, which characterizes the present embodiment, is arranged upstream of the extrusion nozzle 4 in the cylinder 2. The intermediate nozzle 5 has a disc shape, and a large number of circular nozzle holes 6 are formed. The inner diameter d on the push nozzle side of the lower surface of each nozzle hole 6 is the inner diameter D on the cylinder side of the upper surface.
It is set to be smaller, and thereby each nozzle hole 6 is formed in a taper shape toward the extrusion nozzle 4.

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, when passing through each nozzle hole 6 of the intermediate nozzle 5, a strong wall friction is given to the kneaded material 9,
As a result, the SiC whiskers 8 are extruded into a large number of small-diameter rods 10a uniformly arranged in one direction.
Subsequently, the small-diameter rod body 10a is pressure-bonded by the extrusion nozzle 4 to form one compact and large-diameter molded body 10a.
Is pushed out.

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 1800 ° C. for 1 hour to be heated at normal pressure. Sinter. At the time of this sintering, since the SiC whiskers 8 are arranged in the same direction, they do not hinder the shrinkability of the alumina powder 7. As a result, the fiber-reinforced ceramics of this example is manufactured.

As described above, according to this embodiment, the cylinder 2
Since the intermediate nozzle 5 in which a large number of nozzle holes 6 are formed is disposed between the extrusion nozzle 4 and the extrusion nozzle 4, the SiC whiskers 8 can be arranged in one direction by the intermediate nozzle 5 as described in the above mechanism. As a result, a compact and large-diameter molded body 10 can be easily obtained, and problems such as foreign matter mixing and peeling, which occur when the intermediate molded bodies of the prior art publication are stacked, can be solved. As a result, shaft parts and structural materials having excellent mechanical properties such as strength, toughness, and wear resistance can be manufactured, and the reliability of quality can be greatly improved.

Further, in this embodiment, since the compact compact 10 having a large diameter can be obtained only by disposing the intermediate nozzle 5, the shrinkage of the ceramic is improved even if the pressureless sintering is performed. It is possible to eliminate the need for high temperature and high pressure sintering by conventional HIP or hot pressing.

Next, a test conducted to confirm the effect of the manufacturing method according to this embodiment will be described. In this test, an extrusion device having a cylinder diameter of 30φ and an extrusion nozzle diameter of 15φ was adopted, and an intermediate nozzle was arranged in this device. This intermediate nozzle has 26 nozzle holes, the cylinder side inner diameter D of each nozzle hole is 5φ, and the nozzle side inner diameter d is changed to 2φ, 3φ, 4φ, respectively. A kneaded material having a SiC whisker content of 10 wt% was
A molded body was manufactured by extrusion molding according to the method described above. Then, a sample having a vertical cross section (extrusion direction) and a horizontal cross section (direction perpendicular to extrusion) of each molded body was prepared, and the strengths of 111 and 220 faces of SiC whiskers in the molded body were measured by X-ray diffraction. . And Si in the above-mentioned longitudinal section and transverse section
When the strength of the 111 surface of the C whisker was 100, the 220 surface strength of each cross section was obtained. In addition, for comparison, FIG.
As shown in, a molded body was manufactured by an extrusion device without using an intermediate nozzle, and the same measurement was performed for this.

[0020]

[Table 1]

Table 1 shows the above measurement results. As is clear from the table, in the case of the comparative sample molded without using the intermediate nozzle, the arrayability index (longitudinal section 22
The 0 / cross section 220) is as low as 1.07. On the other hand, the array index of each Example sample molded using the intermediate nozzle is 9.74.
It is as high as ~ 19.64 with satisfactory results.

Next, the compacts of the above-mentioned example sample and comparative sample were sintered by the above-mentioned method, and the relative density of each sintered compact was measured. As a result, in the case of the above comparison sample, the relative density
It is 60%, which is not densified because the shrinkage of ceramics is obstructed. On the other hand, the relative density was 95% in the example samples having the nozzle-side inner diameter of 4φ, and 100% in the respective example samples having the inner diameters of 3φ and 2φ. Here, inner diameter 2φ
In the case of the sample of Example 1, there was some vertical cracking. This is due to the difference between the total area of the inner diameter of the nozzle of the intermediate nozzle and the area of the extrusion nozzle. When the inner diameter of the extrusion nozzle was changed to 11φ, a crack-free sintered body was obtained.

Further, according to the method of this embodiment, 3 × 4 × 40
(Mm) 3-point bending test piece was prepared, and the bending test of this test piece was performed at room temperature.
A bending strength of 1.5 to 2.0 times was obtained. Furthermore, the fracture toughness value measured by Micro Vickers (load 50 Kg / mm ² ) was 5.5 to 7.0 M, although anisotropy was observed.
Pam ^1/2 was obtained.

[0024]

As described above, according to the method and apparatus for producing fiber-reinforced ceramics of the present invention, an intermediate nozzle having a plurality of circular nozzle holes is provided on the upstream side of the extrusion nozzle, and the kneaded material is an intermediate nozzle. Since the inorganic fibers are uniformly arrayed in one direction when passing through and then extruded by gathering into one compact, it is possible to obtain a dense and large-diameter ceramic compact. In addition, it is possible to solve the problem of foreign matter mixing, peeling and cracking during manufacturing, and to improve the reliability of quality.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a method and an apparatus for manufacturing fiber reinforced ceramics according to an embodiment of the present invention.

FIG. 2 is a plan view showing an intermediate nozzle of the above embodiment.

FIG. 3 is a cross-sectional view showing an intermediate nozzle of the above embodiment.

FIG. 4 is a diagram showing a comparative sample prepared for confirming the effects of the above-described example.

FIG. 5 is a diagram showing a conventional manufacturing method by extrusion molding.

[Explanation of symbols]

 2 Cylinder 4 Extrusion Nozzle 5 Intermediate Nozzle 6 Nozzle Hole 7 Alumina Powder (Ceramics Powder) 8 SiC Whiskers (Inorganic Fiber) 9 Kneaded Material 10 Large Diameter Molded Body 10a Small Diameter Rod

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 manufacturing the same, by separating the kneaded product into a plurality of small diameter rods, the inorganic fibers in the rods are arranged in the axial direction of the rods, and then the rods are crossed one by one. A method for producing a fiber-reinforced ceramics, characterized in that the fiber-reinforced ceramics is extruded from the extrusion nozzle while being aggregated into a round-shaped molded body. 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. In the manufacturing apparatus of, the intermediate nozzle in which a plurality of small-diameter circular nozzle holes are formed is disposed on the upstream side of the extrusion nozzle in the cylinder, and the extrusion nozzle has a circular shape having a diameter smaller than the cylinder diameter. An apparatus for producing fiber-reinforced ceramics, which is characterized in that