JP2759673B2 - Multi-stage reflective electric furnace - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a reflection type electric furnace, and particularly to a compact multi-stage reflection type capable of heating an object to be heated at an arbitrary temperature gradient without moving or moving the object to be heated. It relates to an electric furnace.

(Conventional technology and problems to be solved) Conventionally, there is a so-called multi-stage electric furnace in which a metal heating element is used, and a heated portion is divided to independently control the temperature.

However, with this method, although a certain degree of temperature gradient can be adjusted, the interaction between heat conduction and radiation between the heating parts is strong, and not only a sharp temperature gradient can be obtained, but also a high-precision arbitrary temperature gradient can be obtained. It was impossible to get.

On the other hand, conventionally, there are various types of electric furnaces of the reflection type.

First, there is an infrared concentrating electric furnace. In this method, the light source of the heat source lamp is placed at the first focal point of the spheroidal reflector, and the sample is heated by condensing it at the second focal point. Is impossible, so that an arbitrary temperature gradient cannot be obtained.

In addition, a transparent electric furnace is provided, in which a heat reflecting surface is provided on the inner wall of a transparent quartz tube, and two electric furnaces each having a metal heating element mounted on the inner surface thereof, and the distance between the two electric furnaces is made variable.
Further, there is an apparatus in which the temperature gradient is adjusted by independently controlling the temperature of each electric furnace. This method is a method in which the largest temperature gradient is obtained among conventional electric furnaces. Still, the temperature gradient obtained is 50 per cm
Up to ° C. The reason is that the interaction between radiation and heat conduction between the two electric furnaces is so strong that a steep temperature gradient cannot be obtained.

Further, there is an infrared reflection type electric furnace in which a heat reflection surface is provided on the back surface of a tubular heat source lamp and a plurality of heat reflection surfaces are arranged vertically or horizontally. In this method, it is conceivable to vary the temperature gradient by controlling the temperature of each lamp independently.However, since the diameter of the lamp is large, the heat reflection surface becomes large accordingly, and it is not possible to obtain a sharp temperature gradient. Can not.

Moreover, in any of the above-described electric furnaces, in order to heat a particularly long object to be heated, it is necessary to heat the object while moving the object in the axial direction of the furnace. Is inevitably long, requires a large installation space, and is not economical.

Further, in recent years, in the field of manufacturing new materials, such as growing single crystals, the demand for a heating method for rapidly changing the temperature gradient has been increasingly strong. It was difficult to respond.

The present invention has been made to solve the above-mentioned problems of the prior art and to meet the above-mentioned demand, and it is possible to easily adjust a steep temperature gradient such as 250 ° C./cm with an arbitrary temperature gradient, and It is an object of the present invention to provide a novel multi-stage reflection type electric furnace which does not need to move the object to be heated.

(Means for Solving the Problems) In order to achieve the above object, the present inventors have conducted intensive research and as a result, provided a plurality of heating elements constituting an electric furnace,
The thickness of each heating element is made as thin as possible, and the interaction between the heating elements by radiation and heat conduction is made as independent as possible,
Further, the present inventors have found out that this is possible by adopting a structural design in which these heating elements can be easily stacked, and have made the present invention.

That is, the multi-stage reflection type electric furnace according to the present invention has a configuration in which a plurality of heating elements are stacked in multiple stages in the furnace axis direction,
Each heating element has a space in the center part, and has a convex portion in the center on the space side in an annular shape, and has an integral shape having a heat reflecting surface that is half of a concave portion on both sides of the convex portion in an annular shape, and It has a structure for cooling the heat reflecting surface, and is characterized in that a heating element made of a metal resistor is arranged in a concave portion formed by stacking each heating element and the heating element.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

(Embodiment) FIG. 1 is an example in which a multi-stage reflection type electric furnace according to the present invention is shown in a longitudinal section thereof, and is an electric furnace formed by sequentially laminating a plurality of heating elements 1 in a multi-stage manner in the furnace axis direction. The furnace body 20 is attached to the gantry 21 via a support arm 22. Of course, other installation forms are possible.

As shown in FIGS. 2 and 3, the heating element 1 is an integral type having a disc-shaped space having a non-uniform diameter substantially in the center of a metal substrate 2 (usually made of copper). an inner (heat reflecting surface) in the recess 2 ₁ and the convex portions 2 ₂ annularly intended cooling structure provided with cooling water channel 3 to the metal substrate, both end faces of the furnace axis direction to the laminated surface 2 ₃ Has become.

Inside each heating element 1, a shape recess 2 ₁ on either side of the central convex portion 2 ₂ is formed as shown in FIG. 3, the recess
2 ₁ constitutes a single complete heat reflecting surface is combined with the concave portion 2 ₁ of Aitonaru heating element 1.

Therefore, the heat reflection surface is formed around the space of the metal substrate 2, but is a curved surface having an arbitrary curvature in consideration of the size of the heating space, the reflection efficiency, and the like. The height or recess 2 ₁ of the depth of the convex portions 2 ₂ is preferably sized to the heating element 4 may be disposed entirely within the recess. When protrudes inwardly from the heating body 4 of the convex portion 2 ₂ tip, to note that the interaction of heat conduction and radiation between the heating portion becomes strong.

Such heating elements, as shown in FIG. 2, which has a cooling structure having a cooling water passage 3 and the entrance 3 _1, 3 _2, temperature measurement, the hole may be inserted a control thermocouple 11 5 And a hole 6 for a set screw for lamination.

The heating element 4 may be made of any suitable material. For example, Ni-Cr, Fe-Al, Pt, Mo, W
And metal resistors that can be easily processed, such as a metal-based or Ta-based material. If these materials are used, heating can be performed up to 1500 ° C. Further, the heating element 4 may have a shape in which a helical wire, a round bar, a square plate, a thin film and the like are formed in a circular shape, and as shown in FIG. It is held by a ceramic 8 for use.

In order to stack such heating elements 1 in multiple stages, first, as shown in FIG. 4, a first heating element is arranged, a heating element 4 is arranged in a concave portion thereof, and then a heating element 4 is arranged thereon. The operation of laminating two heating elements 1 and arranging the heating elements 4 in the recesses is repeated, and a predetermined number of heating elements 1 are laminated in a multi-stage manner in the furnace axis direction. Assembling and arranging the transparent quartz tube 9 for the atmosphere in the electric furnace inside (in the space) forms a multi-stage reflection type electric furnace. The assembly of the heating element 1 can be referred to speak divided split heating element in the lamination plane 2 _3. Reference numeral 10 denotes an electric input terminal of the heating element 4, and reference numeral 12 denotes an electrode terminal of the thermocouple 11.

This multi-stage reflection type electric furnace is designed so that there is no interaction between heat conduction and radiation between the heating units, and by controlling the heat generation of the heating elements arranged in the recesses of each heating element, each heating element However, the temperature can be controlled independently, and an arbitrary thermal gradient can be created in the furnace axis direction (stacking direction). Taking into account the thickness of the heating element and the like, it is possible to create, for example, a steep temperature gradient of up to 250 ° C./cm in the furnace axis direction.

The object to be heated 13 can be set in an arbitrary manner in the furnace (see FIG. 4), and can be heated while being set in the furnace or while being moved. Create a temperature gradient according to the heating pattern of
This temperature gradient pattern can be fixed or moved in the furnace axis direction. At that time, the heating element can be changed to another shape and size, or the number thereof can be changed according to the size of the object to be heated, the heating pattern, and the like.

(Effects of the Invention) As described in detail above, according to the present invention, the thermal interaction between the heating elements can be extremely reduced due to the heat insulating effect of the cooling portion of the heating element and the heat collecting effect of the heat reflecting surface. Since the thickness of the heating element substrate is reduced, and furthermore, it is easily laminated as many times as necessary, by controlling the temperature of the heating elements independently, a steep temperature gradient such as 250 ° C./cm, Alternatively, an arbitrary temperature gradient can be easily obtained, and further, each heating element is independently programmed and controlled,
By sequentially shifting the program, the same effect as the movement of the object to be heated can be obtained without moving the object to be heated in the electric furnace. Specifically, the following excellent effects can be obtained.

(1) The entire long object to be heated can be heated at a constant temperature, and the heat treatment can be performed with a steep temperature gradient or an arbitrary temperature gradient.

(2) When pulling a single crystal, crucible, solid-liquid interface,
The temperature gradient at each position of the pulled crystal can be set arbitrarily.

(3) When pulling up a single crystal, the temperature gradient at the solid-liquid interface in the crucible can be arbitrarily adjusted, and the crystal can be grown down the crucible. Furthermore, since the temperature gradient can be moved upward and the crystal can be grown without lowering the crucible, an electric furnace significantly smaller than the conventional electric furnace can be realized.

(4) If the thickness of the heating element is further reduced by making full use of a technique such as laminating a thin film formed by vapor deposition, sputtering, or the like, and the computer is controlled so that a large number of heating elements can be independently and simultaneously controlled, The ultimate multi-stage reflex electric furnace.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the whole and installation mode of a multi-stage reflection type electric furnace according to the present invention, FIG. 2 is a transverse sectional view of a heating element of the present invention, and FIG. 3 is a longitudinal sectional view of a heating element of the present invention. FIG. 4 is a longitudinal sectional view showing a state in which a large number of heating elements are assembled and showing a usage example in which an object to be heated is set in a furnace. 1 ...... heating element, the metal substrate 2 ...... heating element, 2 ₁ ...... recess (heat reflecting surface), 2 ₂ ...... protrusions, 2 ₃ ...... stacking surface, 3 ...... coolant passage, 3 ₁ ... ... cooling water inlet, 3 ₂ ... cooling water outlet, 4 ...
... heating element, 5 ... insertion hole for thermocouple for temperature measurement and control, 6 ...
Set screw hole for laminating heating element, 8: Ceramic for holding heating element, 9: Transparent quartz tube, 10: Electric input terminal of heating element, 11: Thermocouple for temperature measurement and control, 12: Electrode terminals of thermocouple, 13 ... Heated object, 20 ... Multi-stage reflection type electric furnace, 21 ...
... Stand, 22 ... Support arm.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-B-56-34794 (JP, B2) JP-B 62-5272 (JP, B2) (58) Fields surveyed (Int. Cl. ⁶ , DB name) F27D 11/02-11/04 H05B 3/00

Claims (1)

(57) [Claims] 1. A structure in which a plurality of heating elements are stacked in multiple stages in a furnace axis direction, wherein each heating element has a space in a central portion,
With an annular convex portion in the center of the space side, an integral shape having a heat reflecting surface that is half of the concave portion on both sides of the convex portion,
In addition, the multi-reflection electric furnace has a structure for cooling the heat reflecting surface, and a heating element made of a metal resistor is disposed in a concave portion formed by stacking each heating element and the heating element.