JP2707933B2 - Hot press furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot press furnace particularly preferably used for producing new materials such as fine ceramics with high purity.

[0002]

2. Description of the Related Art Hot pressing is a technique for producing a high-density and high-hardness material by sintering powder under high temperature and high pressure.
The use of various materials for powders makes it possible to develop new materials that had never existed before.Recently, research has been actively conducted, and one of the typical results has been realized as fine ceramics manufacturing technology. ing.

The structure of a conventional hot press furnace, as shown in FIG. 3, has a recess 11 for positioning at the center of the upper surface, and a die support 1 for detachably supporting the die 2.
And a pressing rod 3 at a position opposed to the die receiving table 1 and capable of moving forward and backward with respect to the die receiving table 1, and a rod heater 4 for heating an atmosphere in which the die 2 is arranged.
On the other hand, the die 2 includes a cylindrical die main body 21, a sleeve 22 fitted on the inner periphery of the die main body 21, a receiving member 23 for closing a lower end opening of the sleeve 22, and the sleeve 22. And a pressing tool 24 which is slidably fitted in the upper end opening. The die support 1, the die 2, and the pressing rod 3 are all graphite products. As an operation procedure, first, powder A is filled in the sleeve 22 without the pressing tool 24 outside the furnace, and then the pressing tool 2
4 is temporarily held on the upper end of the sleeve 22 by the pin 24a. Alternatively, the pressing tool 24 is placed directly on the powder A. Next, the die 2 is set on the die receiving table 1 at a position where the receiving member 23 and the concave portion 11 are fitted to each other.
Is turned on, and the pressing rod 3 is operated. As a result, the pressing rod 3 initially presses the pressing tool 24 to remove it from the temporary holding pin 24a, and presses the pressing tool 24 that has dropped once again with a predetermined pressure. This is indicated by imaginary lines in the figure. When the pressing tool 24 falls, the outgas trapped in the die 2 is discharged into the furnace space S through a hole 22a formed in a peripheral wall near the upper end of the sleeve 22 as shown by an arrow X. Is done. As described above, when the powder A is sintered under high temperature and high pressure, the cooling gas (such as N ₂ )
And the die 2 is taken out when the temperature of the furnace has dropped.

[0004]

Incidentally, in order to increase the purity of the raw material, it is necessary to remove impurities contained in the powder A as much as possible before hot pressing. Therefore,
Conventionally, this is achieved by using sufficiently refined powder A. However, since the work of filling the powder A into the die 2 is performed outside the furnace, air is inevitably confined in the die 2, and the die 2 is set in the furnace and subjected to hot pressing. In this case, there is a problem that oxygen and carbon, which are components in the air, impregnate the final product in an oxidized state or a carburized state, thereby deteriorating the quality.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and there is provided a hot press furnace capable of suitably removing impurities from powder in a die while the die is set in the furnace. It is intended to provide.

[0006]

In order to achieve the above object, the present invention employs the following configuration.

That is, in the hot press furnace according to the present invention, a die filled with powder is placed in the furnace, and the powder is sintered at high temperature and high pressure via the die. A gas introduction system for introducing a gas directly from outside the furnace is provided inside the furnace, and exhaust means for exhausting the introduction gas from the die by evacuating the furnace is provided. By means, the gas introduction into the die and the evacuation in the die are alternately performed in a pulsed manner.

[0008]

With such a configuration, if an appropriate gas having high reactivity with impurities is introduced into the die through the gas introduction system, the impurities can be changed into an appropriate gas form and discharged out of the die. it can. In particular, gas introduction into the die
Since the gas is evacuated in the die alternately in a pulsed manner, even if the amount of gas used is small, the gas is evenly brought into contact with the powder in the die and gasification of impurities is effectively promoted. Can be. Therefore, even after setting the die in the furnace, the powder filled in the die can be appropriately refined.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
This will be described with reference to FIG. Parts common to those in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted.

The basic structure of this hot press furnace is the same as that of the conventional furnace shown in FIG. 3, in which a die receiving table 1 on which a die 2 is attached and detached, a pressing rod 3, and a rod heater 4 are provided. The die 2 also includes a die main body 21, a sleeve 22, a receiving member 23, and a pressing member 24.

In this embodiment, when the dice 2 is set on the die receiving base 1, a gas introduction path 5 is formed between the dice receiving base 1 and the dice 2. Like that. Specifically, this gas introduction system 5
The flow path 51 is formed in the thickness of the die receiving base 1, one end thereof communicates with the gas supply unit 7 outside the furnace, and the other end is opened in the center of the recessed part 11. A flow passage 52 having one end communicated with the flow passage 51 and the other end opened to the inner peripheral space of the sleeve 22. Gas can be directly introduced. It should be noted that a cloth 61 made of graphite having air permeability for preventing the powder A from dropping into the gas introduction path 5 is provided on the receiving member 23.
And a graphite spacer 62 having holes in the thickness direction for uniformly dispersing the gas to be introduced.
The furnace space S is connected to a vacuum pump RP disposed outside the furnace for evacuation.

Based on the above configuration, first, the powder A is filled in the die 2 outside the furnace to temporarily hold the pressing tool 24, and once the die 2 is set in the furnace, before the hot pressing step is started, Gas introduction and furnace heating are performed according to the pattern shown in FIG. 2 to remove impurities. That is, first, in step I, the furnace space S is evacuated, and then in step II, the introduction of gas from the gas supply unit 7 and the evacuation by the vacuum pump RP are alternately performed in a pulsed manner. Step III is a process in which the cycle of gas introduction and evacuation is extended, and is performed as necessary. As a result, at the time of gas introduction, the gas uniformly flows into the lower space in the die 2 through the gas introduction path 5, and at the time of evacuation, the gas flows from the upper space in the die 2 into the hole 22 of the sleeve 22.
When such a cycle is repeated, the gas uniformly comes into contact with the powder A in the die 2 and causes a chemical reaction with the impurities to generate a predetermined reaction. Change to gas. As an example, when H ₂ is used as the gas, oxygen and carbon are converted into steam and methane gas, respectively, by a reaction of MeO + H ₂ → Me + H ₂ O C + 2H ₂ → CH ₄ . And those gases H ₂
O and CH ₄ are sucked together with H ₂ through the hole 22 a of the sleeve 22 into the furnace space S, and then discharged out of the furnace by the vacuum pump RP.

With the above configuration, after the die 2 is set in the furnace, the air sealed in the die 2 can be reliably decomposed and removed. Then, by subjecting the thus refined powder A to hot pressing in the next step, it is possible to surely obtain a final product having a higher purity than before.

The present invention is not limited only to the above-described embodiment. For example, as the gas to be introduced, other than H ₂ , an appropriate gas which can react with impurities in the powder and be changed into a gas can be used. Of course, the impurities are not necessarily limited to oxygen and carbon. Further, the present invention can be suitably used for a reaction firing treatment using a gas.

[0015]

According to the hot press furnace of the present invention, the gas can be directly introduced from outside the furnace through the gas introduction system into the die in a state where the die is arranged in the furnace. By introducing an appropriate gas having a high reactivity with impurities, the impurities can be changed into an appropriate gas form and discharged out of the die. In particular, since gas is introduced into the die alternately in a pulsed manner together with the vacuum evacuation in the die, the amount of gas used can be kept to a minimum as much as possible to avoid pressure fluctuations in the furnace. In addition, the gas can be evenly brought into contact with the powder in the die, and gasification of impurities can be effectively promoted. Therefore, there is an effect that the powder filled in the die is appropriately refined, and the purity of the final product can be reliably increased as compared with the related art.

[Brief description of the drawings]

FIG. 1 is an overall cross-sectional view showing one embodiment of the present invention.

FIG. 2 is a view showing a temperature processing pattern and a pressure processing pattern in the embodiment.

FIG. 3 is a sectional view showing a conventional example and corresponding to FIG.

[Explanation of symbols]

 A: powder RP: exhaust means (vacuum pump) 2: die 5: gas introduction system

Claims (1)

(57) [Claims] 1. A hot press furnace in which a die filled with powder is placed in a furnace, and the powder is sintered under high temperature and high pressure through the die. A gas introduction system for introducing
Exhaust means for exhausting the introduced gas from the die by evacuating the furnace is provided, and the gas introduction system and the exhaust means alternately introduce gas into the die and evacuate the die. A hot press furnace characterized in that it is performed in a pulsed manner.