JPS6260138B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an ultra-high pressure generator. The ultra-high pressure generator is made of, for example, diamond,
Used to synthesize cubic boron nitride, etc.

(b) Prior Art As a conventional ultra-high pressure generator, there is one shown in Japanese Patent Publication No. 36-23463, for example. In this method, a pair of anvils are placed facing each other on both end faces of an annular cylinder, a gasket is interposed between the anvils, a pressure chamber surrounded by the anvils and the gasket is formed, and a 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 relatively frequently damaged due to the impact force that is applied during pressurization. If the dimensional accuracy of the gasket or the compressed object is poor, stress concentration will occur in the anvil and cylinder, promoting the occurrence of breakage. 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 boron nitride sintered bodies, etc., it is necessary to increase the size of the ultra-high pressure generator, but in order to do so, the anvil and cylinder made of cemented carbide must be increased in size. No. 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 Application Laid-Open No. 58-27628 discloses that a device for preventing breakage of a cemented carbide anvil and cylinder is provided. According to this method, the probability of breakage of cemented carbide parts can be reduced to some extent, but breakage still occurs quite frequently, so the manufacturing price is still high. Furthermore, the problem of increasing the size of cemented carbide parts remains unsolved.

Additionally, an ultra-high pressure generator has been disclosed in which the cylinder is made of steel and a steel shot piston is attached to a cemented carbide anvil ("Ceramics" Vol. 15, No. 8 (August 1980 issue)). In this case, the steel shot piston must be replaced every time, resulting in low productivity and being uneconomical since the shot 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, conventional ultra-high pressure generators have
There are problems such as damage to the anvil and cylinder made of cemented carbide and restrictions on increasing the size of the device. The present invention aims 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 generator according to the present invention, the cylinder and anvil are made of steel, and the ratio L/D of the distance L between the anvil tips and the inner diameter D of the cylinder center is in the range of 0.75 to 1.0. , the anvil consists of 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. There is. Note that the first and second conical pedestals do not need to have a strictly conical shape, and may be, for example, curved rotating surfaces close to conical pedestals. 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. Further, since steel materials are used, the anvil 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, even with the anvil and cylinder made of steel, it is possible to generate sufficient ultra-high pressure, as shown in the test results described below. .

(F) Example 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, a pair of anvils 12 and 14 (both are the same) arranged oppositely above and below the cylinder 10, A substantially conical cylindrical gasket 16 is interposed between the cylinder 10 and the anvil 12, and a substantially conical cylindrical gasket 18 is interposed between the cylinder 10 and the anvil 14 (this is the same as the gasket 16). ) and has. The cylinder 10 includes an inner core 10a and a tightening ring 10 that preloads the inner core 10a from the outer periphery to generate compressive stress therein.
It consists of b. 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. The anvil 14 likewise consists of a main body 14a and a tightening ring 14b. Main body 12a, main body 14a, tightening ring 1
2b and the tightening ring 14b are made of steel material. The cylinder 10 has a substantially drum-shaped inner diameter, and the anvils 12 and 14 have corresponding shapes as will be described later, and gaskets 16 and 18 are inserted into the gaps formed by these. A pressure chamber 20 is defined by anvil 12, anvil 14, gasket 16, and gasket 18. Pressure chamber 20
A compressed object 22 is sealed inside. Compressed object 22
For example, raw materials necessary for diamond synthesis, solvent metals, pressure media, electrodes for electrical heating,
It consists of a heater, etc. The ratio (L/D) of the dimension L between the lower surface of the anvil 12 and the upper surface of the anvil 14 to the inner diameter D of the central portion of the cylinder 10 is set to a value within the range of 0.75 to 1.0 as described later.
Further, the shape of the anvil 12 (and anvil 14) is determined by the central axis 30, as shown in an enlarged view in FIG.
A circular flat surface 32 centered at and perpendicular to this
and a conical surface 34 continuous from the outer periphery of the flat surface 32.
The flat surface 32 and the conical surface 34 are smoothly connected with a predetermined curvature r ₁ , and the conical surface 34 and the conical surface 36 are Smoothly connected with a given curvature r ₂ . That is, the anvil 12 (and anvil 14) has a first conical pedestal 38 with a conical generatrix angle θ and a second conical pedestal 40 with a conical generatrix angle α.
The shape is a smooth connection between the two. 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, generally 40 to 80°. Set it to around 70° as in the example (α = 72°).

The reason why the above-mentioned L/D value needs to be within the range of 0.75 to 1.0 is as follows. The present inventor found through tests that the value of L/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 the parts are made of steel materials (the anvils 12 and 14 are made of SKH9 steel, and the inner core 10a of the cylinder 10 is made of SKD11 steel), L/
For example, if the value of D is 1.08, even if the maximum load of the press used in the test is 800t, the pressure required for diamond synthesis will be 5.5GPa, as shown in Figure 3.
(In addition, L/D was 1.08
Even in this case, the necessary pressure could be obtained by using an anvil and cylinder made of cemented carbide because of their low elasticity). The pressure generated in the compressed object shown in FIG. 3 was measured in the same manner as the pressure generated in FIG. 4, which will be described later. As shown in Figure 3 and the test examples described below, the value of L/D is
In the case of 0.8 and 0.9, it was found that the necessary pressure could be obtained even by using an anvil and cylinder made of steel. Therefore, if L/D is about 1.0 or less, it is actually possible to synthesize diamond. On the other hand, when the value of L/D is decreased, the length (L) of the object to be compressed 22 is shortened, the reaction space is narrowed, and the yield of the reaction product is decreased, and the tip of the anvil is elongated. It has to be shaped and becomes easily 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 shapes of the anvils 12 and 14 are as shown in FIG.
~25°) for the following reasons. That is, it was found from the test results that when the anvils 12 and 14 are made of steel, the conical generatrix angle θ has a significantly large effect on the pressure generation efficiency within the pressure chamber 20 and the strength of the anvils 12 and 14. Figure 4 shows the results of testing the relationship between the pressure generated within the compressed material and the press load when θ is 15° and 20°. The generated pressure can be measured using a pressure measurement gauge (bismuth with a fixed pressure point of 2.55 GPa, thallium with a fixed pressure point of 3.67 GPa, fixed pressure point
It was determined by measuring the sudden change in electrical resistance when each pressure point of barium (5.5 GPa) 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, we get the cone generating angle θ
It can be seen that when the angle exceeds 25°, the pressure generation efficiency decreases to such an extent that practicality is lost (that is, even a press load of 800 t does not reach 5.5 GPa). In fact, as shown in Test Example 5 below, diamond grains could not be obtained when θ=26°. On the other hand, if the angle θ is less than 10°, the tips of the anvils 12 and 14 will have an elongated shape and will be easily damaged. As shown in Test Example 6 below, the anvil body 12a broke at θ=9°. Therefore, the conical generatrix angle θ needs to 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...SKH9 steel inner core 10a...SKD11 steel D = 25 mm L = 22.5 mm L/D = 0.9 θ = 15° α = 72° r ₁ = 0.5 mm r ₂ = 16.0 mm Compressed product 22... graphite and iron alloy stacked alternately Pressure... 5.5 GPa Temperature... 1350°C Processing time... 7 minutes Under the above conditions, it was possible to obtain 6-octahedral diamond grains of 0.1 to 0.3 mm. .

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

(Test Example 3) When treated under the same conditions as Test Example 1 except for the angle θ=20°, it was possible to obtain hex-octahedral diamond grains of 0.1 to 0.3 mm.

(Test Example 4) When treated under the same conditions as the first test example except for L = 20 mm (L/D = 0.8) and θ = 15 degrees, 6-octahedral diamond grains of 0.1 to 0.3 mm were processed. I was able to get it.

(Test Example 5) When processing was carried out under the same conditions as in the first test example except for L=20 mm (L/D=0.8) and θ=26°, no diamond grains could be obtained.

(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 anvil body 12a was destroyed.

(G) Effects of the Invention As explained above, according to the present invention, the cylinder and anvil are all made of steel material, and even when these shapes are made of steel material, the necessary pressure generation efficiency can be obtained. Moreover, since the shape is difficult to break, the ultra-high pressure generator can be prevented from being damaged and have a long lifespan, reducing the manufacturing cost of the ultra-high pressure generator itself and the replacement of parts while the ultra-high pressure generator is in use. It is possible to reduce the costs required for the above, and it is also possible to easily increase the size of the ultra-high pressure generator.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the ultra-high pressure generator according to the present invention, FIG. 2 is an enlarged view showing the shape of the anvil,
Figure 3 is a diagram showing the relationship between the press load and the pressure generated within the compressed object when L/D = 1.08, 0.9 and 0.8, and Figure 4 is the press load when θ = 15° and 20°. FIG. 3 is a diagram showing the relationship between the pressure generated in the compressed object and the pressure generated within the compressed object. 10...Cylinder, 10a...Inner core, 10b...
Tightening ring, 12...Anvil, 12a...Main body, 1
2b... Tightening ring, 14... Anvil, 14a... Main body, 14b... Tightening ring, 16, 18... Gasket, 20... Pressure chamber, 22... Compressed object.

Claims (1)

[Scope of Claims] 1. A cylinder having an annular shape, a pair of anvils disposed on both end surfaces of the cylinder, and a gasket interposed between the cylinder and the anvil, the pair of anvils and the gasket In an ultra-high pressure generator in which a pressure chamber is divided by 1.0, and 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 with a relatively large conical generatrix angle that smoothly continues from the large end diameter of the first conical pedestal. An ultra-high pressure generator characterized by comprising a conical table.