JPH0476731B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a high-temperature, high-pressure generator used in the synthesis of diamond, cubic boron nitride, and the like.

(Prior technology) In order to synthesize raw materials such as diamond and cubic boron nitride and to sinter their sintered bodies, high pressures of about 60,000 atmospheres and high temperatures of 1,500 to 2,000 degrees Celsius are stably maintained. High-temperature, high-pressure generators are used, and belt-type high-temperature, high-pressure generators in particular are widely industrialized.

As such a high temperature and high pressure generator, for example, as shown in Japanese Patent Publication No. 53-34189,
By considering the angle of the inner slope of the anvil and the size and material of the gasket, it became possible to generate higher pressure, and as a result of subsequent development, the material of the anvil and cylinder was changed from cemented carbide to steel. Therefore, it has become possible to reduce the manufacturing cost.

In recent years, sintered bodies made of diamond and cubic boron nitride have been increasingly produced as tool materials on an industrial scale, but tools with even higher accuracy and longer life and heat sinks that utilize high thermal conductivity have been produced. In order to achieve this, it is necessary to use a powder blend of raw materials with a reduced amount of metal used as a sintering aid compared to the conventional method. The condition is approximately 60,000 atmospheres,
Higher pressure and temperature are required compared to 1500-2000℃.

However, when trying to generate high pressure and high temperature of, for example, 80,000 atm and 2000 to 2500 degrees Celsius using a conventional high temperature and high pressure generator, the burden on the anvil and cylinder becomes greater due to the higher pressure than before. , I was happy that I could only use them 20 to 30 times at most, and sometimes they would be destroyed. Another problem was that the deformation of the pressure generating part, that is, the deformation of the graphite heating element installed between the anvils became large, making it impossible to stably obtain a high temperature. Therefore, in order to obtain sintered bodies made of diamond and cubic boron nitride with higher purity and higher physical properties, there is a need for a device that can consistently and stably generate higher pressure and temperature than conventional high-temperature, high-pressure generators. ing.

(Problems to be Solved by the Invention) The purpose of the present invention is to provide a high-temperature, high-pressure generator that can stably generate higher pressure and temperature than conventional ones, and that has a much longer lifespan. That is.

(Means for solving the problem) A pair of anvils in the shape of a tapered compound convex truncated cone are made into a hollow hole having a central hole with a compound concave conical chamfer on the hole edge corresponding to each conical surface of both anvils. The cylinder is assembled so that the tapered end faces thereof face each other through a pressure seal covering the inner surface and the edge of the chamfered hole, so that the end faces face a pressure chamber formed inside the central hole, and are accessible to each other. In high-temperature, high-pressure equipment equipped with a pressurizing unit, the anvil has a temperature of 25 to 35°C on its tapered end surface.
The pressure seal has a conical half angle of Inner gasket G ₁ and intermediate gasket made of stone material with higher compressive deformability compared to the inner gasket G1.
It has a triple configuration consisting of _G2 and an outer gasket _G3 made of rubber material, and the ratio of the outer diameter _dg3 of the outer gasket _G3 to the diameter dl at the anvil end surface, which is substantially equivalent to the inner diameter of the inner gasket _G1 . This is a high temperature and high pressure generator characterized by: being within the range of 2 to 3.

Now, FIG. 1 shows a pressurizing unit as a main component of the high temperature and high pressure generator according to the present invention, and in the figure,
Reference numerals 1 and 1' denote a pair of anvils in the shape of a tapered compound convex truncated cone, and 2 a hollow cylinder having a central hole 3 for receiving the tapered ends of the anvils.

The hollow cylinder 2 has a compound concave conical chamfer on the edge of the opening of the central hole 3, which corresponds to each conical surface of the anvils 1, 1' having a compound convex truncated conical shape, and the inner surface of the central hole 3 and the chamfer. A pressure seal 4 is interposed between the anvils 1 and 1' over the edge of the hole.

The basics of the above structure are
- Similar to that disclosed in Publication No. 34189, but
In the present invention, each of the anvils 1 and 1' has a conical half angle θ ₁ of 25 to 35°C on the tapered end side, and a conical half angle θ 1 of 30 to 70°, which is larger than θ ₁ , on the side adjacent to this. It has a half angle θ ₂ , and the ratio of the inner diameter db of the central hole of the hollow cylinder 2 to the diameter dl at the tapered end face is within the range of 1.1 to 1.2.

The pressure-resistant seal has an inner gasket _G1 made of a thermally and electrically insulating stone material, an intermediate gasket _G2 made of a stone material with greater compressive deformability, and an outer gasket _G3 made of a rubber material.
The outer diameter of the outer gasket _G3 is triple configuration consisting of
The ratio of dg ₃ to the diameter dl at the end face of the anvil, which is substantially equivalent to the inner diameter of the inner gasket G ₁ , is in the range of 2 to 3.

(Function) The high temperature and high pressure generator of the present invention is
This is an improvement of the technology disclosed in the publication, in which a pair of frustoconical anvils and a cylinder are installed between the pair of anvils, and the conical inclined surface of the anvil is a surface having two steps of inclination. The points are similar, but the cross-sectional angle θ ₁ of the inner inclined surface must be 25 to 35 degrees on one side with respect to the axis, and the cross-sectional angle θ ₂ of the outer inclined surface should be at least 1.2 times θ ₁ . .

Here, if the cross-sectional angle θ ₁ of the inner inclined surface, that is, the half angle of the cone on the tapered end face side of the anvil exceeds 35°, the load applied to the conical face on the tapered end face side becomes excessive, and sufficient pressure generation efficiency cannot be obtained. Also, conversely
If it is less than 25°, the stress supporting effect at the tapered end will be reduced, and especially if a high pressure of 80,000 atmospheres or more is applied, the anvil tip may be damaged or cracks may occur.

Furthermore, it is preferable that the inner inclined surface and the outer inclined surface are connected by a curved surface. By connecting with a curved surface having a large radius of curvature, there is an effect of alleviating stress concentration when high pressure is generated at the connection portion between the inner inclined surface and the outer inclined surface, and the life of the anvil is increased.

Here, the pressure generation efficiency refers to how much of the load applied from above and below the anvils 1 and 1' is applied to the pressure chamber, and how much pressure is generated in the pressure chamber. Evaluate by the load acting on the pressure chamber relative to the load.

The shape of the hollow cylinder 2 is such that the part facing the anvils 1 and 1' through the pressure seal is the 2nd part of the anvil.
It has an inverted conical shape at the same angle as the conical inclined surface of the step, the central part in contact with the pressure chamber is almost vertical, and the ratio db/dl of the cylinder center opening diameter to the anvil tip diameter, that is, the outer diameter of the pressure chamber, is 1.1 ~ Set it to 1.2. If the value of this ratio exceeds 1.2, the gap between the anvils 1, 1' and the hollow cylinder 2 will become too wide, making it easy for the gasket to flow when high temperature and high pressure are generated, resulting in deformation of the pressure chamber, that is, the gap between the anvils 1 and 1' and the hollow cylinder 2 will be too large. Since the deformation of the graphite heating element increases, it is difficult to obtain a stable high temperature. On the other hand, if the ratio is less than 1.1, the pressure generating chamber and the cylinder are too close, and high temperature and high pressure are likely to be applied to the cylinder surface, increasing the risk of cylinder destruction.

Although the graphite heating element is not shown here, it is useful for setting the temperature inside the pressure chamber, and various methods are used for its construction, but one example is a graphite cylinder with current-carrying plates made of copper, molybdenum, etc. placed at both ends. Furthermore, the end faces of the anvils 1 and 1' are abutted through a conductive ring such as one made of steel fitted with an insulating core such as zirconia, and a synthetic raw material or a sintering raw material is filled into the inside of the graphite cylinder with a filling material such as salt. , zirconia-containing salt, boron nitride, etc.

Next, the pressure seal 4 inserted between the hollow cylinder 2 and the anvils 1 and 1' has a thermally and electrically insulating stone gasket on the inside and a stone gasket with greater compressive deformability than the inside in the middle. , and a rubber gasket on the outside. Compared to the conventional case where only one or two types of thermally and electrically insulating gaskets are used, the surrounding gaskets cannot support the high pressure inside the pressure chamber, especially when increasing or decreasing the pressure. First, it is highly effective in preventing troubles such as sudden ejection of filler from inside the pressure chamber to the outside.

That is, the ratio dg ₃ /dl between the outer diameter of the outer gasket G ₃ and the inner diameter of the inner gasket G ₁ is set to 2 or more and less than 3. If this ratio is made larger than 3, as shown by the broken line in FIG. Pressure generation efficiency decreases, making it difficult to generate the required high pressure. Also,
If this ratio is less than 2, the gasket will deform greatly as pressure is generated, and the gasket member will tend to flow out from the outer periphery in the radial direction.
Deformation of the sample and graphite heating element in the pressure chamber occurs, making it difficult to obtain a stable high temperature. Furthermore, the effect of supporting stress on the anvil and cylinder portions becomes insufficient, and the risk of their destruction and damage increases.

The preferred composition ratio of each gasket 4 is that dg ₁ /dl in FIG. ₁ is 1.2 for the inner gasket G 1.
to 1.8, the middle gasket G ₂ has a dg ₂ /dl in FIG. 1 ranging from 1.9 to 2.8, and the outer gasket G ₃ has a dg ₃ /dl ranging from 2 to 3.

A specific example of a stone gasket used for the inner gasket is pyrophyllite.
Al ₂ Si ₄ O ₁₀ (OH) ₂ ) A product cut from raw stone into a desired shape, a specific example of an intermediate gasket is a product obtained by adding a predetermined amount of organic binder to pyrofluorite powder and forming and drying it, and a specific example of an outer gasket. Examples include nitrile rubber.

Hereinafter, the high temperature and high pressure generator of the present invention will be explained in more detail with reference to the drawings. Figure 3 shows the entire high-temperature and high-pressure generator, where 5 and 5' are anvils 1,
1' is a tightening ring, 6 and 6' are safety rings,
7 and 8 are the tightening rings of the hollow cylinder 2, 9 is the safety ring, 10 is the pressure chamber, 11 and 11' are the upper parts,
This is the pressure plate below.

(Example) Hereinafter, the present invention will be explained in detail by giving Examples and Comparative Examples.

Example ₁ As shown in _FIG .
The relationship db/dl between 1′ was chosen to be 1.15. Inner diameter dl of inner gasket G ₁ and outer diameter of outer gasket G ₃
The ratio with dg ₃ is dg ₃ /dl = 2.5, and dg ₁ /dl is 1.5,
dg ₂ / dl is 2.4, inner gasket G ₁ is cut from pyrofluorite rough, middle gasket G ₂
Pyrofluorite powder is molded and solidified,
Nitrile rubber was used for the outer gasket _G3 .

Also, the thickness lg of the outer gasket _G3 in the pressurizing direction is given by the distance ld between the anvils before pressurization.
lg/ld=0.24.

When we evaluated the pressure generation efficiency by measuring the electrical resistance change due to the phase transition of bismuth metal while applying pressure with this device, we found that it could easily generate 7.7GPa, the bismuth transition point, as shown by the solid line in Figure 2. done. In addition, the sample taken out after the pressure measurement was pressed uniformly with little lateral protrusion.

On the other hand, when we placed a platinum-rhodium thermocouple in the pressure chamber 10 to generate high temperature and pressure and measured the temperature, we found that even at 2500°C, which was extrapolated from the relationship between input power and thermocouple temperature, the temperature did not decrease as the heating current decreased. This was not observed and a stable high temperature was obtained.

No damage or cracks were observed in the anvils 1 and 1' and the hollow cylinder 2 even after the high temperature and high pressure generation of 80,000 atm and 2000°C or more was performed more than 200 times.

Comparative Example 1 A gasket with dg ₃ /dl = 3.1 was installed on the same anvils 1 and 1' as in Example 1 and the hollow cylinder 2,
A pressure generation experiment was conducted. As a result, as shown by the broken line in Figure 2, only about 75% of the pressure was generated compared to Example 1, which was 7.7GPa for bismuth.
No phase transition point was detected.

Comparative Example 2 A gasket with dg ₃ /dl = 1.9 was installed on the anvils 1, 1' and hollow cylinder 2 similar to those in Example 1,
As a result, the gasket flowed out significantly and the reaction chamber was significantly deformed, making stable high-temperature, high-pressure experiments impossible.

Comparative Example 3 A gasket with dg ₃ /dl = 2.3 was installed on the same anvils 1 and 1' as in Example 1 and the hollow cylinder 2,
A pressure generation experiment was conducted, but in this case, the gasket was double-layered, an inner and outer gasket, a pyrofilite gasket was used for the inner gasket, a nitrile rubber was used for the outer gasket, and dg ₁ /dl was set to 2.1. As a result, the pressure generation efficiency was almost the same as in Example 1, but a blowout phenomenon was observed in which the gasket could not support the high-pressure pressure chamber 10 and instantly blew out when the pressure was removed after a high temperature was generated. However, stable high-temperature, high-pressure experiments were not possible.

Comparative Example 4 The shape of the anvils 1 and 1' shown in Fig. 1 is θ ₁ =
20°, θ ₂ = 72°, hollow cylinder 2 and anvil 1,
The relationship between 1′, db/dl is selected as 1.25, and dg ₃ /dl=5.5
High temperature and high pressure were generated using a gasket.

After generating 80,000 atm, when attempting to generate a temperature exceeding 2000°C, the heating current decreased significantly and a temperature drop phenomenon was observed. Also, on the 22nd test, the tips of anvils 1 and 1' were damaged.

Comparative Example 5 The shape of the anvils 1 and 1' shown in Fig. 1 is θ ₁ =
Hollow cylinder 2 and anvil 1 at 40°, θ ₂ = 80°,
1′ relationship db/dl is selected as 1.15, dg ₃ /dl=2.5
High temperature and high pressure were generated using a gasket.

As a result, as shown in FIG. 2, the pressure generation efficiency was low and high pressure could not be obtained.

Comparative Example 6 The shape of the anvils 1 and 1' shown in Fig. 1 is θ ₁ =
30°, θ ₂ = 60°, the relationship between cylinder and anvil
db/dl was selected to be 1.06, and a gasket with dg ₃ /dl = 2.5 was used to generate high temperature and high pressure.

After being exposed to high temperatures and pressures of 80,000 atmospheres and over 2,000 degrees Celsius five times, a crack appeared in the center of the cylinder and the cylinder was destroyed.

(Effect of the invention) According to the present invention, the anvil of the high temperature and high pressure generator,
The life of the cylinder has been dramatically increased, and
A high pressure of 10,000 atmospheres can be generated steadily, and a high temperature of 2,000 to 2,500 degrees Celsius can be stably obtained.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a processing unit consisting of an anvil, cylinder, gasket, and pressure chamber, which is the central part of the high-temperature and high-pressure generator, and Fig. 2 is a graph showing the pressure generated in the pressure chamber against the press load. FIG. 3 is a sectional view of the overall configuration of the high temperature and high pressure generator. 1, 1'...anvil, 2...hollow cylinder,
3...Hollow hole, 4...Pressure seal, 10...Pressure chamber.

Claims (1)

[Claims] 1. A pair of anvils in the shape of a tapered compound convex truncated cone are formed into a hollow cylinder having a central hole whose hole edge is chamfered in a compound concave cone shape corresponding to each conical surface of both anvils. , through a pressure-resistant seal covering the inner surface and the chamfered hole edge, the tapered end surfaces face each other, and the end surfaces face the pressure chamber formed inside the central hole, and are assembled so as to be mutually accessible. In high-temperature, high-pressure equipment equipped with a
The pressure seal has a conical half angle of Inner gasket G ₁ and intermediate gasket made of stone material with higher compressive deformability compared to the inner gasket G1.
A triple configuration consisting of _G2 and an outer gasket _G3 made of rubber material, and the ratio of the outer diameter _dg3 of the outer gasket _G3 to the diameter dl at the anvil end surface which is substantially equivalent to the inner diameter of the inner gasket _G1 . is within the range of 2 to 3. A high temperature and high pressure generator characterized by: