JPH092875A - Silicon carbide-based ceramic sintered compact - Google Patents

Abstract

PURPOSE: To obtain the subject sintered compact having a combination of fracture toughness and high-temperature strength. CONSTITUTION: This ceramic sintered compact is obtained by multiplicating silicon carbide with a multiple carbide of at least two kinds of metals among groups IVa, Va and VIa transition metals and/or carbonitride of one kind of metal among the above transition metals and/or multiple carbonitride of at least two kinds of metals among the above transition metals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon carbide based ceramics sintered body useful as a structural member for high temperature, for example.

[0002]

2. Description of the Related Art A silicon carbide group is promising as a structural material for high temperature because it has excellent high temperature strength, but it is difficult to apply it as a structural material because of its low fracture toughness. In order to improve fracture toughness, an example in which IVa, Va, or VIa group transition metal carbide such as titanium carbide is compounded with silicon carbide has been studied, and improvement of fracture toughness has been confirmed by compounding these metal carbides. Has been done.

[0003]

In order to improve the fracture toughness as described above, it is effective to add a transition metal carbide of group IVa, Va or VIa, which is a group IVa, group Va or group VI.
Since the a-group transition metal carbide causes plastic deformation at high temperature,
The high temperature strength of the silicon carbide based ceramic compounded with this is remarkably reduced. Therefore, it is difficult to achieve both fracture toughness and high temperature strength. Therefore, an object of the present invention is to provide a silicon carbide based ceramics sintered body having both fracture toughness and high temperature strength.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above technical problems, and as a result, selected IVa, Va, and VIa group transition metal carbides as additive materials from double carbides or double carbons. It has been found that, by compounding as a nitride, it is possible to suppress the plastic deformation of these additive materials and obtain a silicon carbide based ceramics having excellent fracture toughness and high temperature strength, and completed the present invention.

That is, the invention according to claim 1 is a silicon carbide-based ceramics sintered body, wherein silicon carbide contains two or more kinds of transition metals of group IVa, group Va and group VIa of the periodic table of elements. Double Carbide and / or Group IVa, Va
A complex carbonitride of one kind of a transition metal of Group VIa group and / or a double carbonitride of a metal of two or more kinds of transition metal of group IVa, Va, VIa. It is a characteristic silicon carbide based ceramics sintered body. Also,
In the invention according to claim 2, the double carbide is (Ti, M
o) C or (Ti, W) C, the carbonitride is Ti (C, N), and the double carbonitride is (Ti, M).
o) (C, N) or (Ti, W) (C, N) is the silicon carbide based ceramics sintered body according to claim 1.

Hereinafter, the present invention will be described in detail. The present invention provides silicon carbide with the periodic table of elements IVa, Va, and VI.
An object of the present invention is to obtain a silicon carbide based composite material excellent in high temperature strength and fracture toughness by compounding a group a double carbide-based, carbonitride-based or double carbonitride-based solid solution particles. Examples of Group IVa transition metals include titanium, zirconium, and hafnium. Moreover, vanadium, niobium, and tantalum can be mentioned as a Va group transition metal. Further, as the VIa group transition metal, chromium, molybdenum, and tungsten can be cited.

The above-mentioned double carbides are group IVa, group Va, and group VI.
It is a solid solution of at least two metals selected from the group a transition metals and carbon. Such double carbides include (Ti, Mo)
C and (Ti, W) C are preferred.

The carbonitrides are IVa group, Va group, and VI group.
It is a solid solution of one or more metals selected from Group a transition metals and carbon and nitrogen. As such a solid solution, Ti (C, N)
Is preferred. Further, the double carbonitride is a group IVa, V
It is a solid solution of at least two metals selected from the group a and VIa transition metals and carbon. As such a solid solution, (Ti, M
o) (C, N) or (Ti, W) (C, N) are preferred.

In the case of a double carbide, for example, these solid solutions are formed by solid solution of a single carbide of a transition metal of IVa group, Va group and VIa group with a single carbide of another transition metal of these groups. Further, these solid solutions are compounded within the solid solution limit to form a complete solid solution, or partially solidified and partially have a single carbide or a single nitride. Things are also included. It should be noted that the effects of the present invention can be remarkably obtained by eliminating the impurities contained in silicon carbide, which is a raw material of the silicon carbide-based ceramics sintered body, and these solid solutions. Examples of such impurities include Fe-based impurities. The Fe-based impurities can be removed from the raw material by performing an acid treatment with hydrochloric acid or the like.

Each of these double carbides, carbonitrides and double carbonitrides can be independently compounded with silicon carbide,
It is also possible to form a composite with a plurality of types of double carbides. Further, two or more kinds of compound carbides, carbonitrides, and compound carbonitrides may be combined to form a composite. Further, the ratio of the compound carbide or the like to silicon carbide can be appropriately selected from the viewpoints of sintering conditions, required strength, etc., but is 20 vo
A ratio of 1% or more and 50 vol% or less is preferable. 20 vo
If it is less than 1%, improvement of fracture toughness is insufficient, and 50 vo
This is because if it exceeds 1%, the high temperature strength becomes insufficient.
Since the compounding in the present invention is to compound a solid solution, it is a normal pressure firing method using a die press, a rubber press, or a preformed body by CIP, a hot press or a HI.
A pressure sintering method such as P can be used. Further, a vibration mixing method, a dry ball mill method, a wet ball mill method, a turbo mill method, or the like can be used before the preparation of the preformed body.

[0011]

EFFECTS OF THE INVENTION According to the silicon carbide-based ceramics sintered body of the present invention, since the solid solution of double carbide, carbonitride, or double carbonitride is contained in the matrix of silicon carbide, the temperature of the carbide in silicon carbide is high. The plastic deformation at 1 is suppressed by the solid solution, and the high temperature strength of the sintered body can be prevented from lowering.

[0012]

Embodiments Embodiments embodying the present invention will be described below. In this example, a silicon carbide-based matrix raw material containing silicon carbide as a main matrix (SiC 98 parts by weight, B 0.5 parts by weight, C 1.5 parts by weight), two kinds of double carbides (Ti _0.9 , Mo _0.1 ) C, (Ti _0.9 ,
W _0.1 ) C, or carbonitride Ti (C _0.7 , N _0.3 ).
Using as a raw material, a sintered body was obtained by the manufacturing process shown in FIG.
That is, as shown in Table 1, various double carbides or carbonitrides were used in this silicon carbide-based matrix raw material so that the internal ratio to SiC was 40 or 50 vol%, using SiC balls, SiC pots, and ethanol. Wet pulverization was performed.

[0013]

[Table 1] *: However, vol% as SiC This mixed pulverized product was sieved with 440 mesh, dried and collected under vibration reduced pressure, and finally 60 mesh was sieved to obtain a granulated powder. This is uniaxially pressure-molded with a 42 mm x 47 mm mold to obtain various preforms (42 mm x 47 mm).
mm).

For each of these preforms, 2150
Various examples 1 to 5 were obtained by performing hot press sintering under an Ar atmosphere at a temperature of 1 ° C. for 1 hour under an axial load of 40 MPa. In addition,
As a control, titanium carbide (TiC) was added to the same silicon carbide-based matrix at an internal ratio of 0 to 5 with respect to SiC.
0 vol% (0, 20, 34, 40 and 50 vol%)
Comparative Example 1
5 was produced. These Examples 1-5 and Comparative Examples 1-5
The three-point bending test (JIS R1601 JIS Handbook 1) at room temperature and high temperature (test temperature 1500 ° C)
991 ceramics) and fracture toughness (IF method, JISR
1607, JIS Handbook 1991 Ceramics) was measured.

In the test, Examples 1 to 5 and Comparative Examples 1 to 5 were used after being processed into a shape according to each test method. Specifically, the room temperature three-point bending test, the sample shape 3mm
The test was carried out at a span of 30 mm and a crosshead speed of 0.5 mm / min with a size of 4 mm x 40 mm. Further, the high temperature three-point bending test was performed in an Ar atmosphere at 1500 ° C., and the sample shape, span and crosshead speed were the same as those in the room temperature bending test. In addition, the IF method uses a test surface of 0.5μ.
Polished with m diamond slurry, 98N, 1
The test was conducted in 5 seconds. These results are shown in FIGS.
Shown in

FIG. 2 shows the results of three-point bending test and fracture toughness measurement for Comparative Examples 1-5. As is clear from this result, the fracture toughness increases with an increase in the amount of TiC added. On the other hand, the strength in the three-point bending test changes in the range of 600 to 900 MPa at room temperature,
When TiC is 20 vol%, the maximum value is exhibited, and the high temperature strength is remarkably lowered with an increase in the amount of TiC added.
From the point where the amount of iC added is 34 vol% in the plot, it is 25-26 vol in the graph drawn by connecting the plots.
From the point of%, the result is lower than room temperature strength.

On the other hand, in the first and second embodiments,
The point bending test and the fracture toughness measurement results are shown in FIG. 3, and the measurement results of Comparative Example 4 are also shown. As is clear from this figure, in Comparative Example 4, the high temperature strength is significantly reduced (470 MPa) with respect to the room temperature strength, whereas in Examples 1 and 2, the same room temperature strength as in Comparative Example 4 is obtained. While maintaining, high temperature strength is about 600 and 750 respectively
It exhibits MPa and double carbides (Ti _0.9 , Mo _0.1 )
An increase in high temperature strength was observed with the addition of C or (Ti _0.9 , W _0.1 ) C.

Regarding fracture toughness, both Examples 1 and 2 exhibited higher values than Comparative Example 4, and the effect of increasing fracture toughness was also observed.

Further, the measurement results of the strength of Examples 3 to 5 are shown in FIG. 4 and the measurement results of Comparative Example 5 are also shown. According to this result, in Comparative Example 5, the high temperature strength is remarkably reduced as in Comparative Example 4, while in Examples 3 to 5, the high temperature strength is higher than that of Comparative Example 5. And double carbide (Ti _0.9 , Mo _0.1 ) C,
(Ti _0.9 , W _0.1 ) C or carbonitride Ti
It was confirmed that the addition of (C _0.7 , N _0.3 ) increased the high temperature strength. On the other hand, regarding the room temperature strength, Example 3 to
5 is approximately 650 MPa, 800 MPa,
650 MPa, 650-800 M of Comparative Examples 1-5
It almost coincided with the fluctuation range of Pa, and the room temperature strength was maintained at the same level.

In the above examples, the results of testing IVa and VIa group transition metal double carbides and carbonitrides of the periodic table of elements are shown. However, other transition metals of the same family and Va group transition metal compounds are shown. Similar results can be confirmed for carbides, carbonitrides, double carbonitrides, and combinations thereof.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of samples of Examples and Comparative Examples.

FIG. 2 is a graph showing the results of measurement of fracture toughness and strength of Comparative Examples 1-5.

FIG. 3 is a graph showing the results of measuring fracture toughness and strength in Examples 1 and 2.

FIG. 4 is a graph showing the strength measurement results of Examples 3-5.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Kazama Inventor Koichi Kazama 1 20-20 Kitakanyama, Odaka-cho, Midori-ku, Nagoya-shi, Aichi Chubu Electric Power Co., Inc. Electric Power Research Laboratory (72) Inventor Ken Mitsuoka Nagoya, Aichi 2-4-1, Rokuno, Atsuta-ku In the Fine Ceramics Center (72) Inventor Hideaki Matsubara 2-4-1, Rokuno, Atsuta-ku, Nagoya, Aichi Prefecture Inside the Fine Ceramics Center

Claims (2)

[Claims] 1. A silicon carbide-based ceramics sintered body, wherein silicon carbide contains silicon carbide of group IVa, group Va, or group VIa of the periodic table of elements.
Double carbides of two or more kinds of group transition metals and / or carbonitrides of one kind of group IVa, Va, or VIa transition metals and / or groups IVa, Va, VIa
A silicon carbide-based ceramics sintered body, which is obtained by compounding a double carbonitride of two or more kinds of group M transition metals. 2. The double carbide is (Ti, Mo) C or (Ti, W) C, and the carbonitride is Ti (C, N).
The silicon carbide based ceramics sintered body according to claim 1, wherein the double carbonitride is (Ti, Mo) (C, N) or (Ti, W) (C, N).