JP2000226603A - Hybrid sintering apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sintering apparatus and a method thereof capable of performing rapid heating and uniform heating, thereby producing a thin sintered material with a low heat conductive material. SOLUTION: A heater heating device 12 which has a heater 2 surrounding a sintering die 1 and heats the sintering die from the surface, and a raw material powder 3 filled in a sintering space of the sintering die are directly sandwiched and the outer periphery thereof. The upper and lower heat equalizing plates 14 whose portions are in contact with the sintering mold, the upper and lower energizing heating elements 16 which sandwich the upper and lower heat equalizing plates from above and below and whose outer peripheral portion does not contact the sintering mold, and An electric heating device 18 is interposed between the pair of electrodes 4 and electrically heated between the electrodes. The heat equalizing plate 14 is set to have sufficiently higher thermal conductivity and heat capacity than the raw material powder, and the electric heating element 16 is set to have sufficiently higher electric resistance than the raw material powder. And the electric heating are used in combination to rapidly heat the soaking plate to soak, and heat and sinter the raw material powder during the heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintering apparatus capable of rapidly and uniformly heating a raw material powder filled in a sintering mold and a method therefor.

[0002]

2. Description of the Related Art A sintered body is manufactured by filling a raw material powder of a conductive object such as ceramics, metal, carbide, nitride or the like into a sintering mold, heating and pressing with a pair of punches. The sintering apparatus for producing this sintered body is classified into several types depending on the heating method.

In the heater heating method, a heater such as a resistance heater is arranged around a sintering mold, and the sintering mold is heated from the surface.
In this method, the raw material powder is indirectly heated, and is widely applicable to sintering of both ceramics and conductive materials. The induction heating method is a heating method in which the sintering die is directly heated by electromagnetic induction, and has an advantage that the heating speed of the sintered body is faster than that of the heater heating method. The energization method is a method in which electric power is supplied to the raw material powder using a pair of punches as electrodes, and the raw material powder is heated by resistance heat. The energization method is described in JP-A-64-55303 and JP-A-5-70804.
It is disclosed in JP-A-5-117707.

[0004]

With the recent increase in the size of the sintered body, the size of the object to be heated, such as a sintering die and a punch, has also increased.
In particular, for the production of semiconductors and the like, a thin and large disk-shaped polycrystalline material (for example, about 1 mm in thickness × about 100 mm in diameter) is heated and sintered at a uniform and high temperature (for example, 500 ° C. or more) to conduct heat. It may be required to produce a low conductivity material with a low modulus. That is, in the case of a functional material such as an electronic material, it is necessary to reduce the sintered thickness as much as possible in order to simplify a post-process. Also, some materials have extremely poor thermal conductivity.

[0005] The characteristics of such a polycrystalline sintered material are greatly affected by the size of crystal grains and the microstructure of the material typified by the characteristics of the grain interface. Therefore, in order to obtain a low heat conductive material, it is necessary to make the crystal grains as small as possible,
Therefore, a heating rate as fast as possible is required. Also,
Since the size of the crystal grains varies due to the variation of the heating rate, in order to homogenize such a polycrystalline material,
It is necessary to heat the whole uniformly.

However, in the above-described heater heating method, the energy transfer to the sintering mold is mainly determined by the heater surface temperature and the inner wall temperature of the heat insulating enclosure surrounding the heater, and the heat resistance of the heater material and the heat insulation enclosure is limited. Therefore, there is a limit in energy transmission. Therefore, there has been a problem that the heating time cannot be reduced beyond a certain limit, and since the object to be heated becomes larger, the temperature difference from the central portion becomes larger and the uniform heating cannot be performed because the object to be heated becomes larger. In addition, in the induction heating method, the sintering mold can be directly heated, but there is a problem that uniform heating cannot be performed similarly to the heater heating method because a temperature difference occurs between the sintering mold and the material due to the material characteristics of the object to be heated. Was. Furthermore, a large and expensive high-frequency power generator is required, and there is a problem that power supply equipment is too expensive to shorten the heating time.

On the other hand, in the energization method, the heating time is relatively short because the raw material powder is directly heated, but the heating condition varies depending on the type of the raw material powder, and the operation is difficult. In addition, the temperature tends to be highest at the center temperature of the raw material powder, and it is difficult to control the temperature of the sintered body. Particularly, in the case of a thin and large disc-shaped polycrystalline material, there is a problem that high-speed heating cannot be performed because the material itself generates little heat, and uniform heating is difficult because the material is thin.

In other words, in the conventional sintering apparatus of the heater heating method, the induction heating method and the current-carrying method, when the sintering thickness is reduced by using a material having extremely poor thermal conductivity, rapid heating and uniform heating are compatible. As a result, the temperature distribution of the object to be treated deteriorated, and the yield as a product was reduced.

The present invention has been made to solve such a problem. That is, an object of the present invention is to provide a sintering apparatus and a method thereof capable of performing rapid heating and uniform heating and thereby producing a thin sintered material with a low heat conductive material.

[0010]

According to the present invention, there is provided a heater (12) having a heater (2) surrounding a sintering die (1) for heating the sintering die from the surface, and a sintering die. Upper and lower heat equalizing plates (14) which directly sandwich the raw material powder (3) filled in the sintering space and whose outer peripheral portion is in contact with the sintering mold; An upper and lower energizing heating element (16) that does not come into contact with the sintering mold; and an energizing heating device (18) that sandwiches the upper and lower energizing heating element between a pair of electrodes (4) and energizes and heats the space therebetween. The heat plate is set to have sufficiently higher thermal conductivity and heat capacity than the raw material powder, and the current-carrying heating element is set to have sufficiently higher electric resistance than the raw material powder. The heating plate is rapidly heated to a uniform temperature using heating, and the raw material powder in the meantime is heated and fired. Hybrid sintering apparatus characterized in that it is provided.

According to the present invention, there is further provided a heater (12) for surrounding the sintering mold (1), the heater heating device (12) for heating the sintering mold from the surface, and a pair of electrodes (4). And an electric heating device (18) for electrically heating the raw material powder (3) filled in the sintering space of the sintering mold. Directly sandwiching the heat equalizing plate, the heat conductivity and heat capacity of the heat equalizing plate are set to be sufficiently larger than those of the raw material powder, and the upper and lower heat equalizing plates are arranged from above and below, and the upper and lower electric heating elements (16) in which the outer peripheral portion does not contact the sintering mold. ), And the electric resistance of the energized heating element is set to be sufficiently higher than that of the raw material powder, and the uniform heating plate is uniformly heated at a high speed by using the heater heating and the electric heating together, thereby heating the raw material powder. -A hybrid sintering method characterized by sintering is provided.

According to the apparatus and method of the present invention, since the heater heating and the electric heating are used in combination, the heater is heated from the side surface of the sintering die, and the electric heating is used to heat the sintering die from above and below. Even when the diameter of the powder is increased (for example, alumina powder having a diameter of 60 mm or more), the temperature difference in the radial direction can be reduced.

That is, since the raw material powder (3) is directly sandwiched between the upper and lower heat equalizing plates (14) having a heat conductivity and a heat capacity sufficiently larger than those of the raw material powder, the heating of the raw material powder is performed by the heat equalizing plate. Heat conduction is mainly performed, and even when the raw material powder is thin, heating is performed in the thickness direction, so that uniform heating and high-speed heating can be performed.

Further, the outer peripheral portion of the heat equalizing plate is in contact with the sintering mold (1), and the sintering die is heated from the side surface by heating the heater, so that the temperature of the outer peripheral portion of the heat equalizing plate is prevented from lowering. The heat can be efficiently transferred from the sintered mold. Furthermore, the upper and lower current-carrying heating elements (1.
In step 6), since the upper and lower heat equalizing plates are sandwiched from above and below, and the outer peripheral portion of the electric heating element is not in contact with the sintering mold, the electric heating element is heated by applying current independently of heater heating, and the heat is used to equalize the heat. The hot plate can be heated in the thickness direction, and the central portion can be efficiently heated. Therefore, the heating plate (14) can be rapidly heated to a uniform temperature by using the heater heating and the electric current heating together, and the raw material powder (3) sandwiched therebetween is rapidly and uniformly heated in the thickness direction. A thin sintered material can be manufactured with a low heat conductive material.

According to a preferred embodiment of the present invention, a temperature sensor (19a, 19b) for detecting the center temperature of the energized heating element and the surface temperature of the sintering mold, and a control for controlling the heater heating device and the energized heating device. A central temperature of the heating element and a surface temperature of the sintering mold are detected and compared. When the central temperature is low, the current is increased, and when the surface temperature is low, the heater is increased. Increase the current. This allows
By reducing the difference between the center temperature of the current-carrying heating element and the surface temperature of the sintering mold, the entire soaking plate can be heated at a substantially constant temperature.
Since the raw material powder (3) is directly sandwiched between the upper and lower heat equalizing plates (14) whose thermal conductivity and heat capacity are sufficiently larger than the raw material powder, even if the raw material powder is thin, it is heated in the thickness direction. Uniform heating and high-speed heating are possible.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
This will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of the hybrid sintering apparatus of the present invention. As shown in this figure,
The hybrid sintering device 10 of the present invention includes a heater heating device 12, upper and lower soaking plates 14, upper and lower energizing heating elements 16, and an energizing heating device 18.

The heater heating device 12 has a resistance heater 2 surrounding the sintering die 1, and heats the sintering die 1 from the surface. The sintering mold 1 has a hollow cylindrical shape and is made of, for example, graphite, and the center of the inside is a sintering space for filling the raw material powder 3. The resistance heater 2 is surrounded by a heat insulating enclosure (not shown) and maintains heat insulation. The heater 2 is a sintered mold 1
Are arranged concentrically at regular intervals around the heater power source 13.
And heat is generated. The power supply 13 is controlled by the control device 20.

The upper and lower heat equalizing plates 14 directly hold the raw material powder 3 filled in the sintering space of the sintering mold 1. The outer peripheral portion of the heat equalizing plate 14 is in contact with the inner surface of the sintering mold 1. Further, the heat equalizing plate 14 is set to have sufficiently higher thermal conductivity and heat capacity than the raw material powder 3. For example, when the raw material powder 3 is a thin disk having a thickness of about 1 mm and a diameter of about 100 mm, and has a small heat conductivity and a small heat capacity (= volume × density × specific heat), the heat conductivity of the heat equalizing plate 14 is reduced. A material that is several tens or more times higher, for example, a copper alloy, is used and its thickness is increased by several tens or more times so that the heat capacity (= volume × density × specific heat) is set to be several tens times or more. With this configuration, the heating of the raw material powder 3 is mainly performed by heat conduction from the heat equalizing plate 14, and even when the raw material powder 3 is thin, the raw material powder 3 is heated in the thickness direction to enable uniform heating and high-speed heating.

The upper and lower current-carrying heating elements 16 are arranged on the upper and lower heat equalizing plates 1.
4 is sandwiched from above and below, and its outer peripheral portion is not in contact with the inner surface of the sintered mold 1. The electric heating element 16 is set to have a sufficiently large electric resistance than the raw material powder 3. For example, even when the raw material powder 3 has a thin disk shape and a small electric resistance, and thus generates a small amount of heat due to energization, a material having an electric resistance several tens times or more as high as the electric heating element 16, such as SiC, is used. Set the thickness several tens of times or more. Further, the electric heating element 16 may be configured as a laminate of metal plates, and may be configured to generate heat by the contact resistance. With this configuration, it is possible to generate heat in the energizing heating element 16 by energizing independently of the heating of the heater, and to heat the soaking plate 14 in the thickness direction with the heat, thereby efficiently heating the central portion.

The electric heating device 18 includes upper and lower electric heating elements 1.
6 is sandwiched between a pair of electrodes 4, during which DC or AC is supplied from a power supply 22 to electrically heat the current-carrying heating element 16 sandwiched between the electrodes. That is, a solid cylindrical energizing heating element 16 is inserted above and below the inside of the sintering mold 1 with a gap, and the electrodes 4 are provided above and below the energizing heating element 16. The electrode 4 constitutes a punch for pressing the heating element 16 and energizes the heating element 16. A hydraulic device (not shown) is connected to the upper and lower ends of the electrode 4 so as to press the heating element 16.

As shown in FIG. 1, the hybrid sintering apparatus 10 of the present invention further comprises temperature sensors 19a and 19b for detecting the center temperature of the electric heating element 16 and the surface temperature of the sintering mold 1.
Is provided. The detection signals of the temperature sensors 19a and 19b are input to the control device 20 to control the heater heating device 12 and the electric heating device 18.

In the hybrid sintering method of the present invention using the above-described hybrid sintering apparatus 10, (a) the raw material powder 3 filled in the sintering space of the sintering mold 1 is brought into contact with the sintering mold at the outer periphery. (B) The upper and lower heat equalizing plates 14 are directly sandwiched by upper and lower heat equalizing plates 14, and the upper and lower heat equalizing plates 14 are sandwiched from above and below by upper and lower energizing heating elements 16 whose outer peripheral portions are not in contact with the sintering mold. The heating plate is rapidly heated to a uniform temperature by using the heating in combination, thereby heating and sintering the raw material powder.

The control device 20 compares the center temperature of the current-carrying heating element 16 detected by the temperature sensors 19a and 19b with the surface temperature of the sintering mold 1. When the center temperature is low, the current is reduced. When the surface temperature is low, the heater current is increased. Thereby, the difference between the center temperature of the current-carrying heating element 16 and the surface temperature of the sintering mold 1 can be reduced, and the entire soaking plate can be heated at a substantially constant temperature.
However, since the heat conductivity and heat capacity are directly sandwiched between the upper and lower heat equalizing plates 14 which are sufficiently larger than the raw material powder, even if the raw material powder is thin, the raw material powder can be heated in the thickness direction to achieve uniform heat and high-speed heating. .

[0024]

Embodiments of the present invention will be described below in comparison with a conventional example. Table 1 shows the external dimensions of the workpiece (raw material powder), sintered mold (mold), electrode (ram), and current-carrying heating element used in the test, and Table 2 shows their physical property values (density,
Thermal conductivity, specific heat, volume resistivity). The heat equalizing plate had the same diameter as the inner diameter of the mold, and the same thickness as the current-carrying heating element.

[0025]

[Table 1]

[Table 2]

That is, the heat equalizing plate 14 has a thermal conductivity and a heat capacity which are several tens times or more larger than that of the raw material powder 3, and the electric heating element 16 is several tens times or more than the raw material powder 3. The electric resistance is set large enough.

FIG. 2 is an embodiment of the present invention showing a change in temperature of an object to be processed. In this figure, A and B are the central temperature (A) and the outer peripheral temperature (B) of the object to be processed by the conventional heater heating, and C and D are the central temperature (C) and the outer peripheral temperature (D) in the case of the conventional energizing heating. ), E and F are the central temperature (E) and the peripheral temperature (F) according to the present invention. The horizontal axis is the elapsed time (m
in), and the vertical axis indicates temperature (° C.). From this figure,
In the case of heating with a heater, it takes a long time to increase both the center temperature (A) and the outer peripheral temperature (B), and it takes at least one hour to reach 500 ° C. or more.

FIG. 3 is a diagram showing the temperature difference of the object to be processed in the embodiment of FIG. In this figure, (A) shows the temperature difference of the object to be processed by the conventional heater heating (center temperature−outer peripheral temperature), (B) shows the temperature difference in the case of the conventional energizing heating,
(C) is a temperature difference according to the present invention. The horizontal axis indicates the elapsed time (min), and the vertical axis indicates the temperature difference (° C.). From this figure, it can be seen that the temperature difference is about 70 even after one hour or more in heater heating.
It can be seen that it takes 60 minutes or more for the temperature difference to be about 20 ° C. or less in the case of energization heating. In contrast, in the apparatus and method of the present invention, the temperature difference is reduced to about 20 ° C. or less in about 20 minutes.

FIG. 4 is a diagram showing a temperature difference of an object to be processed in another embodiment. In this example, the outer diameter / inner diameter of the sintering mold 1 is 300/100 mm, and the thickness of the raw material powder 3 (object to be processed) is 10 mm. Others are the same as those in FIGS. 1 and 2. . From this figure, even when the raw material powder 3 is thick, the thermal conductivity and heat capacity of the heat equalizing plate 14 are set to be sufficiently larger than those of the raw material powder 3, and
It can be seen that a small temperature difference can be achieved in a short time as compared with the conventional heater heating (A) or current heating (B), as long as the electric resistance is set sufficiently higher than that of the raw material powder 3.

It should be noted that the present invention is not limited to the above-described embodiments and examples, and it is needless to say that various changes can be made without departing from the gist of the present invention.

[0031]

As described above, in the hybrid sintering apparatus and method according to the present invention, since the heating is performed not only on the side but also in the vertical direction, the diameter of the processed material is increased (for example, the diameter is 6 mm).
When the diameter is 0 mm or more (alumina powder), the temperature deviation in the radial direction can be reduced, and the reduction time of the temperature deviation can be shortened (1/2 of the conventional ratio). In addition, the optimum conditions for energization and external heating can be set according to the resistance and heat conduction characteristics of the material, so that the optimum sintering conditions according to all physical characteristics can be controlled.

Therefore, the hybrid sintering apparatus and method according to the present invention are capable of rapid heating and uniform heating, and have excellent effects such as being able to produce a thin sintered material with a low heat conductive material. Having.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a hybrid sintering apparatus of the present invention.

FIG. 2 is an embodiment of the present invention showing a temperature change of an object to be processed.

FIG. 3 is an embodiment of the present invention showing a temperature difference of an object to be processed.

FIG. 4 is another embodiment of the present invention showing a temperature difference of an object to be processed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sintering type 2 Heater 3 Raw material powder 4 Electrode 10 Hybrid sintering device 12 Heater heating device 13 Heater power supply 14 Heat equalizing plate 16 Electric heating element 18 Electric heating device 19a, 19b Temperature sensor 20 Control device 22 Electric power supply

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Koichi Fujita 1 Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Ishikawashima Harima Heavy Industries, Ltd. (72) Inventor Yasuhiro Mogaki 3-1-1 Toyosu, Koto-ku, Tokyo No. 15 Ishikawajima Harima Heavy Industries, Ltd. Technical Research Laboratory F term (reference) 4K018 EA22 EA24 HA08 4K061 AA03 BA09 CA08 CA11 DA05 GA02 4K063 AA07 BA04 BA12 BA15 CA03 FA02 FA18 FA29

Claims (4)

[Claims] A heater (1) having a heater (2) surrounding a sintering die (1) and heating the sintering die from the surface.
2) and the raw material powder filled in the sintering space of the sintering mold (3)
Upper and lower heat equalizing plates (14) directly sandwiching the outer peripheral portion and contacting the sintering mold, and upper and lower heating elements that sandwich the upper and lower heat equalizing plates from above and below and the outer peripheral portion does not contact the sintering mold ( 16)
An electric heating device (18) for sandwiching the upper and lower electric heating elements between a pair of electrodes (4) and applying electric heating between them, wherein the heat equalizing plate has a sufficiently higher thermal conductivity and heat capacity than the raw material powder. It is set, and the electric heating element is set to have a sufficiently large electric resistance than the raw material powder, thereby simultaneously using the heater heating and the electric heating, and rapidly heating the heat equalizing plate to a uniform temperature. A hybrid sintering apparatus characterized by heating and sintering the raw material powder during that time. 2. A temperature sensor (19a, 19b) for detecting a center temperature of an electric heating element and a surface temperature of a sintering die, and a control device (20) for controlling a heater heating device and an electric heating device.
A hybrid sintering apparatus, comprising: comparing the detected center temperature with the surface temperature; increasing the conduction current when the center temperature is low, and increasing the heater current when the surface temperature is low. . 3. A heater heating device (1) having a heater (2) surrounding a sintering die (1) and heating the sintering die from the surface.
2) and an energizing heating device (18) for energizing and heating between a pair of electrodes (4). The outer peripheral portion of the raw material powder (3) filled in the sintering space of the sintering mold is sintered. The thermal conductivity and heat capacity of the heat equalizing plate are set to be sufficiently larger than those of the raw material powder. It is sandwiched between upper and lower energizing heating elements (16) that do not come into contact with the mold, and the electric resistance of the energizing heating elements is set sufficiently higher than the raw material powder. A hybrid sintering method comprising heating at a high speed to heat, thereby heating and sintering the raw material powder. 4. A method of detecting and comparing the center temperature of the current-carrying heating element and the surface temperature of the sintering mold. When the center temperature is low, the current is increased, and when the surface temperature is low, the heater current is increased. And a hybrid sintering method.