JPS63153387A - Hot press device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hot press apparatus used for compacting and sintering ceramics, metals, etc., particularly in a vacuum.

(Prior Art and its Problems) Conventionally, hot presses have been widely used to press and sinter powders or temporary compacts of ceramics, metals, etc.

The furnace core of this hot press device will be explained as follows with reference to the drawings. As shown in the longitudinal cross-sectional views of FIGS. 1 and 2, the furnace core of the hot press device includes a die (1),
Heating element (coil for induction heating, heater for resistance heating)
(2), a heat insulating material (3), a sintered body (4), a spacer (5), a push rod (6), and a push stand (7).

Conventionally, the graphite material used for the push rod (6) and push stand (7) of the hot press device has a thermal conductivity of 120 kcal.
/m-hr·°C to 130 kcal/m-hr·°C, which is surprisingly large, was used, and it was therefore difficult to obtain a desirable soaking zone due to heat loss due to heat conduction.

In addition, since the push rod (6) penetrates the insulation material (3) vertically, there was a lot of heat loss due to convection or radiant heat from the openings, resulting in poor thermal efficiency compared to a general furnace.

For this reason, a push rod (6
), but the temperature at which oxide ceramic materials can be used is limited due to their heat resistance, and their compressive strength drops rapidly as the temperature rises, resulting in the disadvantage that the press pressure must be kept low. Ta. On the other hand, if a graphite material is used for the push rod (6) and an oxide ceramic is used for the push stand (7), the graphite material and the oxide ceramic tend to react at high temperatures, so the contact surface between the two There is a need to reduce the temperature of the press rod (6), which requires the push rod (6) to be extremely long.

On the other hand, has it been considered to insert a thermally directional graphite sheet between the push rod (6) and the push stand (7), or is it likely that it will peel off as the number of uses increases, or that the thermal conductivity of the contact surface will vary? It has the disadvantage that it cannot be used stably for a long period of time because it expands.

The above graphite sheet is attached to a push rod (6) and a push stand (7).
Its lifespan was limited by high-temperature plastic deformation.

(Means for Solving the Problems and Their Effects) This invention was made for the purpose of eliminating and improving these drawbacks of the conventional hot press apparatus, and the present invention will be explained below mainly using drawings. do.

FIG. 3 is a longitudinal cross-sectional view of the furnace core of the hot press apparatus of the present invention, and more specifically, the thermal conductivity at room temperature is 70.
The furnace core of a hot press equipment is equipped with a push rod (6a) and a push stand (7a) made of a carbon material with a temperature of kcal/m-hr・℃ or less and a compressive strength of 800 kg/crn" or more. It shows.

Generally, graphite material has a thermal conductivity of 100kca at room temperature.
l/m-h "・℃~1lOkCa1/m-hr・℃.The push rod (5) and push stand (7) used in the hot press device are coated with coal tar pitch or the like to particularly increase the compressive strength. Therefore, the thermal conductivity further increases to 120kcal/m-hr・℃～130k
cal/m-hr·0C, and the current situation is that sufficient uniform heating cannot be obtained due to heat loss due to heat transfer from the push rod (6) and the push stand (7).

In order to solve these problems, the present inventor has developed a push rod (6a) and a push stand (7a) using a carbon material with a thermal conductivity of 70 kcal/m-hr・℃ or less at room temperature.
), the present invention was completed based on the new discovery that the heat loss can be halved and the heat uniformity of the die (1) can be improved.

For example, the carbon material described above has a graphitization temperature of 260
It can be obtained by heating the temperature to 0°C to 2700°C. In the carbon material obtained in this way, the graphite crystals are not as developed as in general graphite material, or the carbon material has been subjected to a sufficiently high thermal history due to the temperature used in hot pressing, so it can be used without any problems. .

On the other hand, 1
As a result of repeated hot pressing with a press pressure of 00 kg/cm'' at 1800°C, the plastic deformation of the push rod (6) increased at the fifth time, and the diameter of the push rod (6) increased by 3 mm near the contact surface with the spacer (5). As a result, it became difficult to insert into the die (1).

As a solution to this problem, by constructing the push cup (6a) and the push stand (7a) using a carbon material with a compressive strength of 800 kg/cm' or more, plastic deformation under high temperature and high pressure can be reduced to 1/20% compared to the conventional one. It has been newly discovered that the following is a low limit.

To increase the compressive strength, the graphitization temperature of the carbon material is set to 2600°C to 2700'C, which is slightly lower than the conventional temperature, thereby increasing the compressive strength of the carbon material to 800 kg.
/crn' or more.

Therefore, the thermal conductivity at room temperature is 70 kcal/m-
hr・℃ or less, and compressive strength is 800kg/cm
Carbon materials with a graphitization temperature of 2600℃~2
This can be achieved at the same time by setting the temperature to 700'C.

Furthermore, whether it is desirable to use an isotropic carbon material to obtain higher strength is not particularly limited to the use of an isotropic carbon material.

(Effects of the Invention) As detailed above, by using the hot press device obtained by the present invention, heat loss can be reduced, a preferable soaking zone can be obtained, and the life of the carbon material can be greatly extended. can be improved.

As a result, it was confirmed that the push rod could be made shorter than before, and the volume of the furnace could be reduced, dramatically increasing thermal efficiency.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional views showing the furnace core of a conventional hot press apparatus, and FIG. 3 is a longitudinal sectional view of the furnace core of the hot press apparatus of the present invention. Explanation of symbols 1... Dice, 2... Heater or coil, 3...
・Insulating material, 4... Sintered body, 5... Spacer, 6
...-Conventional push rod, 6 a - Push rod of the present invention, 7...
- Push stand, 788 push stand of the present invention. that's all

Claims (1)

[Claims] The push rod and push stand of the high-temperature hot press are constructed using a carbon material whose thermal conductivity at room temperature is 70 kcal/m・hr・℃ or less and whose compressive strength is 800 kg/cm^2 or more. A hot press device featuring: