JPS6171831A - Ultra-high pressure generation apparatus - Google Patents

Abstract

PURPOSE:To make damage hard to generate and to facilitate scale-up, by forming a steel anvil from a first truncated once with a conical generatrix angle of 10-25o and a second truncated cone smoothly continued from the large diameter part of the first truncated cone and having a relatively conical generatrix angle. CONSTITUTION:The ratio L/D of the dimension L between the under surface of an anvil 12 and the upper surface of an anvil 14 and the inner diameter D of a cylinder 1 at the central part thereof is set to 0.75-1.0. The shape of the anvil 12 around the center axis 30 thereof has a circular flat surface 32 crossing said center oxis 30 at right angles, the conical surface 34 continued from the outer periphery of the flat surface 32 and the conical surface continued from the conical surface 34 and having different inclination. Each of the anvils 12, 14 is set to a shape wherein a first truncated cone 38 with a conical genera trix angle theta and a second truncated cone 40 with a conical generatrix angle alphaare smoothly connected. The conical generatrix angle theta of the first truncated cone 38 is set to 10-25o and the generatrix angle alpha of the second truncated cone is made larger than said angle theta.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an ultra-high pressure generator. An example of an ultra-high pressure generator is diamond.

Cubic nitride is used to synthesize materials such as boron.

(b) Conventional technology Conventional ultra-high pressure generators include 1, for example,
There is one shown in Japanese Patent No. 23463. In this system, a pair of anvils are placed facing each other on both end surfaces of an annular cylinder, a gasket is interposed between the two, a pressure chamber is formed surrounded by the anvil and the gas get, and compressive force is applied to both anvils. It was made to work. The inner core and anvil that make up the cylinder are made of cemented carbide so that they can withstand the high pressure generated in the pressure chamber. However, since cemented carbide lacks elasticity, it is frequently damaged by impact forces when pressurized. If the dimensional accuracy of the gasket or the compressed object is poor, stress concentration will occur in the anvil and cylinder, promoting damage. The cost of producing synthetic diamonds, for example, is very high because the very expensive cemented carbide anvils and cylinders often break. In addition, in order to manufacture large synthetic diamonds, cubic crystal nitride, sintered bodies, etc., it is necessary to increase the size of the ultra-high pressure generator, which requires increasing the size of the anvil and cylinder made of cemented carbide. However, manufacturing large cemented carbide parts is not easy in terms of manufacturing equipment, manufacturing technology, manufacturing cost, etc.

JP-A-45-15584 discloses that cylinders are manufactured using steel materials such as high-speed steel, tool steel, and die steel. However, in this case as well, the anvil is made of cemented carbide, and the problems of damage to the anvil and enlargement of the anvil have not been solved.

Further, Japanese Patent Laid-Open No. 58-2762Q discloses that a device for preventing breakage of a cemented carbide anvil and cylinder is provided. According to this, the probability of breakage of cemented carbide parts can be reduced to some extent, but the manufacturing cost is still high because breakage still occurs quite frequently. Furthermore, the problem of increasing the size of cemented carbide parts remains unsolved.

In addition, an ultra-high pressure generator has been disclosed in which the cylinder is made of steel and a short steel piston is attached to a cemented carbide anvil ("Ceramics J Vol. 15 No. 8 (1988).
In this case, the steel short piston must be replaced every time, resulting in low productivity and being uneconomical since the short piston is disposable. Furthermore, in this case as well, the problem of increasing the size of the ultra-high pressure generator has not been solved.

(c) Problems to be solved by the invention As mentioned above, the conventional ultra-high pressure generating device has one problem: damage to the cemented carbide anvil and cylinder and restrictions on increasing the size of the device. The purpose of the invention is to solve these problems and provide an ultra-high pressure generating device using an anvil and a cylinder that is hard to break and easy to increase in size.

(D) Means for Solving the Problems The present invention uses steel materials such as high-speed steel, tool steel, spring steel, and stainless steel to construct all parts of the ultra-high pressure generator, and moreover, the anvil and The above object is achieved by giving the cylinder a shape that allows it to generate a sufficient ultra-high pressure without being damaged. That is, in the ultra-high pressure generating device according to the present invention, the cylinder and anvil are made of steel, and the ratio L/D of the distance between the anvil tips and the inner diameter of the silling center is 0.75 to 1°0. The anvil has a first conical pedestal with a conical generatrix angle in the range of 10 to 25 degrees, and a second conical pedestal that smoothly continues from the large end diameter of the first conical pedestal and has a relatively large conical generatrix angle. It consists of. Note that the first and second conical pedestals do not need to be strictly conical in shape; for example, they may be curved rotating surfaces close to conical truncated surfaces, so in this specification, "conical pedestal" refers to a similar shape to a conical pedestal. shall include things.

(E) Effect With the above structure, the anvil and cylinder are less likely to be damaged because the steel material has higher elasticity than cemented carbide. In addition, since steel materials are used, the anobyl and cylinder can be easily manufactured and the cost can be reduced.

Moreover, since parts can be made larger easily compared to cemented carbide, a large ultra-high pressure generator can be constructed. In addition, by configuring the anvil and cylinder with the above-mentioned dimensional relationship, it is possible to generate sufficient ultra-high pressure even with the anvil and cylinder made of steel, as shown in the test results described below. .

(F) Embodiment FIG. 1 shows an ultra-high pressure generator according to the present invention. This ultra-high pressure generator includes an annular cylinder 10 whose axis is vertically arranged, and a cylinder 10 that faces above and below. A pair of anvils 12 and 14 (both are the same) arranged as shown in FIG.
0 and an anvil 14, a substantially conical cylindrical gas get 18 (this is the same as the gasket 16) is provided. The cylinder 10 has an inner core loa
and a tightening ring 10b that preloads the inner core loa from the outer periphery to generate compressive stress therein. Both the inner core 10a and the tightening ring 10b are made using a steel material such as high speed steel, tool steel, die steel, or the like.

The anvil 12 consists of a main body 12a and a tightening ring 12b that protects the main body 12a. Anvil 14 is also 1
The main body 12a, which consists of a main body 14a and a clamping ring 14b, the main body 14a, the clamping ring 12b, and the clamping ring 14b are made of steel material. The cylinder 10 has a generally drum-shaped inner diameter portion, and has an anvil 12 and an anvil 14.
The anvil 12 . Anvil 1
4. A pressure chamber 20 is defined by the gasket 16 and the gasket 18. A compressed object 22 is contained in the pressure chamber 20.
is included. The object to be compressed 22 includes, for example, raw materials necessary for diamond synthesis, a solvent metal, a pressure medium, an electrode for electrical heating, a heater, and the like. Anvil 1
2 and the upper surface of the anvil 14.

The ratio (L/D) of the central inner diameter of the cylinder 10 is set to a value within the range of 0.75 to 1.0, as will be described later. The shape of the anvil 12 (and anvil 14) is as shown in FIG. The conical surface 34 has a conical surface 34 and a conical surface 36 continuous from the conical surface 34 and having a different slope. The flat surface 32 and the conical surface 34 are smoothly connected with a predetermined curvature rl, and the conical surface 34 and the conical surface 36 are smoothly connected with a predetermined curvature r2. That is, the anvil 12 (and anvil 14) has a shape in which a first conical pedestal 38 with a conical generatrix angle θ and a second conical pedestal 40 with a conical generatrix angle α are smoothly connected. The conical generatrix angle θ of the first conical pedestal 38 is within the range of 10 to 25°, and the generatrix angle α of the second conical pedestal 40 is larger than this.

The reason why the above-mentioned L/D value needs to be within the range of 0.75 to 1.0 is as follows.
It has been found through tests that the value of D greatly affects the pressure generation efficiency of the compressed object 22 in the pressure chamber 20 and the yield of synthetic diamond. When all parts are made of steel materials (anvil 12 and anvil 14) is SKH
Made of 9m and the inner core 10a of the cylinder 10 is 5KDII
For example, if the L/D value is 1.08, even if the maximum load of the press used in the test is 800t, the third
As shown in the figure, the pressure required for diamond synthesis is 5.5
GPa could not be obtained (note that L/D was 1.
Even in the case of 08, when using an anvil and cylinder made of cemented carbide, the necessary pressure could be obtained due to the small elasticity); The pressure was measured in the same manner as in the measurement of the generated pressure shown in FIG. 4, which will be described later. As shown in Figure 3 and the test examples described below, when the L/D value is 0.8 and 0°9, it is possible to obtain the necessary pressure even if an anvil and cylinder made of steel are used. Understood. Therefore, L/D is 1.0
It is actually possible to synthesize diamond if the amount is below. On the other hand, when the value of L/D is decreased, the compressed object 22
The length L) becomes shorter, the reaction space becomes narrower, and the yield of the reaction product decreases. In addition, the tip of the anvil has to be made into a long and narrow shape, making it more likely to be damaged. For this reason, it is not preferable to make the value of L/D smaller than 0.75. Therefore, the value of L/D needs to be in the range of 0.75 to 1.0.

Next, the reason why the anvils 12 and 14 are shaped as shown in FIG. 2 (in particular, the conical generatrix angle θ is 10 to 25 degrees) is as follows.

In other words, the test results showed that when the anvil 12 and the anvil 14 are set to El, the conical generatrix angle θ has a significantly large effect on the pressure generation efficiency in the pressure chamber 20 and the strength of the anvil 12 and the anvil 14. The figure shows the results of testing the relationship between the pressure generated within the compressed object and the press load when θ is 15 degrees and 206 degrees.
was used as an electrode, and each pressure measurement gauge (bismuth with a fixed pressure point of 2655 GPa, thallium with a fixed pressure point of 3.67 GPa, and barium with a fixed pressure point of 5.5 GPa) was installed at the center of the compressed object 22 in the pressure chamber 20. This was determined by measuring the sudden change in electrical resistance when the temperature was reached. From the results shown in FIG. 4, it can be seen that as the cone generating line angle θ increases, the pressure generation efficiency decreases. Extrapolating this result, it can be seen that when the cone generating angle θ exceeds 25°, the pressure generation efficiency decreases to the extent that it loses practicality (that is, even a press load of 800 t does not reach 5.5 GPa). As shown in Test Example 5 below, θ=
No diamond grains could be obtained with 26@.

On the other hand, if the angle θ is less than 101, the tips of the anvil 12 and the anvil 14 will have an elongated shape and will be easily damaged. As shown in Test Example 6 below, the anvil body 12a broke when θ=9°. Therefore, one generating line angle θ of the cone
must be in the range of 10 to 25 degrees.

Next, the results of a test in which diamond grains were actually manufactured using the ultra-high pressure generator according to the present invention will be explained.

(Test Example 1) Anvil 12, Anvil 14...5KI ('1m inner core 10a...oSKDII steel D=25m L=22.5mm L/D=0.9 θ; 15@α=72@rl= 0.5mm rz=16.0mm Object to be compressed 22... Φ graphite and iron alloy stacked alternately Pressure: 5.5 GPa Temperature conflict: 91350°C Processing time: ψ 7 minutes 0.1 due to the above conditions It was possible to obtain hex-octahedral diamond grains of ~0.3 mm.

(Test Example 2) Test Example 1 except that L=20 mm (L/D=0.8)
When processed under the same conditions as 0.1 to 0.3 mm, 6
It was possible to obtain -octahedral diamond grains.

(Test Example 3) When processing was carried out under the same conditions as in Test Example 1 except for the angle θ=200, it was possible to obtain hex-octahedral diamond grains of O,L ~0.3 mm.

(Test Example 4) When processed under the same conditions as the first test example except for L = 20 mm (L / D = 0.8 °) and 0215 degrees,
To obtain hex-octahedral diamond grains of 0.1 to 0.3 mm. was completed.

(Test Example 5) When processed under the same conditions as the first test example except for L = 20 mm (L/D = 0.8.) and θ: 26°,
It was not possible to obtain diamond grains.

(Test Example 6) When processing was performed under the same conditions as in the fifth test example except for θ=9°, diamond grains could be obtained, but the anobyl main body 12a was destroyed.

(g) As described in detail, according to the present invention, the cylinder and anvil are all made of steel, and even when these shapes are made of steel, the necessary pressure generation efficiency can be obtained. In addition, it has a shape that is difficult to break, so it can prevent damage to the ultra-high pressure generator and extend its life.
The manufacturing cost of the ultra-high pressure generator itself and the cost of replacing parts while the ultra-high pressure generator is in use can both be reduced, and the ultra-high pressure generator can be easily enlarged. Become.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an ultra-high pressure generator according to the present invention;
Figure 2 is an enlarged view showing the shape of the anvil, Figure 3 is L/D
A diagram showing the relationship between the press load and the pressure generated by the material to be compressed when = 1.08, 0.9 and 0.8, the fourth factor is θ
FIG. 3 is a diagram showing the relationship between the press load and the pressure generated by the material to be compressed when the angle is 15° and 20°. 10@...Cylinder, 10a...Inner core, 10b...
...Tightening ring, 12##-Anvil. 12aΦ# Dream body, 12b, fist, tightening ring, 14...
Q anvil, 14 &... main body, 14b-φ/tightening ring, 16, 18... gasket, 20... pressure chamber,
22...Object to be compressed. Patent applicant: Science and Technology Agency, Inorganic Materials Research Institute, Nikki Steel Co., Ltd. Agent: Patent attorney: Toshiyuki Miyauchi Figure 1 Figure 2

Claims (1)

[Claims] It has an annular cylinder, a pair of anvils disposed on both end surfaces of the cylinder, and a gasket interposed between the cylinder and the anvil, and a pressure chamber is partitioned by the pair of anvils and the gasket. In an ultra-high pressure generator, the cylinder and anvil are made of steel, and the distance L between the anvil tips and the inner diameter D at the center of the cylinder are
The ratio L/D is in the range of 0.75 to 1.0, and the anvil has a first conical pedestal whose cone generatrix angle is in the range of 10 to 25 degrees, and a large end diameter part of the first conical pedestal. An ultra-high pressure generating device comprising a second conical pedestal that is smoothly continuous and has a relatively large conical generatrix angle.