KR101439051B1 - ＭｏＳｉ₂-BASED COIL HEATER AND TUBULAR HEATER MODULE HAVING THE SAME - Google Patents

Abstract

The present invention relates to a MoSi ₂ -type coil heater comprising a coil having an inner diameter (D) not smaller than 300 mm, wherein the inner diameter (D) of the coil and the heater-to-heater distance (t) :
0.9? T / (D / 2) ^1/2? 4.0.

Description

[0001] The present invention relates to a MoSi2-based coil heater and a tubular heater module including the MoSi2-based coil heater.

The present invention relates to a MoSi ₂ -type coil heater and a tubular heater module using the same.

MoSi ₂ (molybdenum disilicide) -based heaters are used in tubular heat treatment furnaces that can be used at high temperatures in the atmosphere. For example, semi-cylindrical wave-type multi-shank heaters and cylindrical spiral (coil type) heaters as disclosed in JP-A-8-143365 are known as MoSi ₂ -bearing heaters. Semi-cylindrical wave-type multi-chuck heaters have been used in large-scale tubular heat treatment furnaces. When the inside diameter of a half-cylindrical wave-type multi-jet heater becomes large, there is an inherent problem such as the difficulty of installation because the half-cylindrical wave-type multi- to be. On the contrary, the cylindrical spiral (coil type) heater has a problem of thermal deformation and temperature uniformity when the coil inner diameter of the heater is not smaller than 300 mm, and the cylindrical spiral (coil type) heater is not present in the present situation.

The present invention has achieved the above considerations. It is an object of the present invention to provide a MoSi ₂ -coil heater having an excellent durability and temperature uniformity and a diameter not smaller than 300 mm.

The inventor of the present invention has found that the MoSi ₂ -type coil heater having high temperature uniformity and little thermal deformation can be used even when the inner diameter D of the coil is not smaller than 300 mm (that is, The inner diameter (D) of the spiral and the distance (t) between the predetermined range of heaters, the inventor of the present invention has reached the present invention.

The present invention MoSi ₂ comprises a coil having an inner diameter (D) of not less than 300 mm - a coil heater type, the distance (t) between the inner diameter of the coil and heater are conditions 0.3≤t / (D / 2) ^{1 / 2} & le; 4.5.

Preferably, the MoSi ₂ -type coil heater according to the present invention is disposed in a coil-shaped groove formed in the inner circumference of the ceramic mold.

In the MoSi ₂ -type coil heater according to the present invention, the inner diameter (D) of the coil and the distance t between the heater satisfy the above-described relational expression, and the temperature uniformity is maintained high with rapid temperature rise by the MoSi ₂ -type heater Thereby contributing to miniaturization of the apparatus and improvement of the production rate. Further, by satisfying the above-mentioned relational expression, the MoSi ₂ -coil heater can freely expand and contract in the groove formed on the inner circumferential surface of the ceramic mold, so that the MoSi ₂ -coil heater can be in a free state. Therefore, it is possible to provide a tubular heater module that avoids problems such as breakage due to restrictions in the ceramic mold. The MoSi ₂ -type coil heater and the tubular heater module according to the present invention are effectively used in a heat treatment apparatus used in a semiconductor manufacturing process, a glass or metal melting furnace, and the like.

FIGS. 1A, 1B and 1C are views showing an example of a process for producing a semi-conductor intermediate material by bending an electrically heated MoSi ₂ -based heater wire in the production of a MoSi ₂ -based coil heater according to the present invention, Here, FIG. 1A shows the stage before bending, FIG. 1B shows the middle stage of bending, and FIG. 1C shows the stage after bending.
2 is a view showing an example of a process of manufacturing a coil-type heater by joining members of a semicircle by electric welding in the production of a MoSi ₂ -coil heater according to the present invention.
FIG. 3 is a view showing a part of a section of a tubular heater module according to the present invention, wherein a MoSi ₂ - system coil heater is disposed in a groove formed in each ceramic mold.
Fig. 4 is a view showing a criterion for making a decision on the basis of the life test as to whether or not the heater is deformed.

Class intermediate member is not greater than (one half) each MoSi _2-based compression-molding a powder material, and MoSi _2-based powder material a ratio within a vacuum from the wire material of a maximum of about 2000 mm length is obtained by sintering in an oxidizing environment And a coil heater according to the present invention is produced in such a manner that the intermediate member is formed into a coil shape by electrically butt bonding called diffusion bonding. However, the method of producing the coil heater according to the present invention is not limited to the above-described method.

[1] Production of MoSi ₂ -series heater wire material

The MoSi ₂ -type heater wire material according to the present invention is obtained by forming a green body for extrusion molding containing MoSi ₂ powder, a binder, water and the like and then forming a rod-like raw material ), And the rod-shaped material is dried, debound and sintered. Water-soluble binders such as methyl cellulose, swellable bentonite, and the like can be used as the binder. Despite changes in sintering depending on the composition of the MoSi ₂ -based material and the desired structure, the sintering is performed in a non-oxidizing environment in a temperature range from about 1350 ° C to about 1600 ° C. The wire diameter of the MoSi ₂ -type heater wire material is preferably in the range of 2 mm to 12 mm. If the wire diameter is larger than 12 mm on, MoSi ₂ in the drying step after the extrusion-type is difficult to produce a heater wire material-MoSi _2, because of cracks in the system the heater wire material occurs. A terminal wire material having a diameter approximately two times larger than the heater wire diameter is generally used for a MoSi ₂ -bearing heater to suppress heating of the terminal portion. Considering the productivity of the terminal wire material, it is preferable that the wire diameter of the MoSi ₂ - system heater wire material is not larger than 12 mm. More preferably, the wire diameter is in the range of 2 mm to 8 mm. More preferably, the wire diameter is in the range of 3 mm to 6 mm.

[2] production of semicircular members

The intermediate member, semicircular member for MoSi ₂ - system coil heater production is produced by electric bending. Figures 1a, 1b and 1c schematically show a process for producing semicircular intermediate members. First, the opposite ends of the MoSi ₂ -based heater wire material 1 are fixed to the clamping portion 2 of the electric bending device and the wire material 1 is called through the clamping portion 2 electrification to the plasticized state (Fig. 1A). Thereafter, as the heater wire material 1 is electrically heated, the clamp portion 2 is pulled and moved along the guide 3 made of several pins (the number of fins is adjusted according to the size of the coil) (Fig. 1B). Finally, the two clamp portions 2 are moved in the direction of 90 [deg.] Relative to the original linear direction of the heater wire material 1 until the two clamp portions 2 are parallel to each other. The temperature is preferably in the range of 1400 ° C to 1550 ° C and the tensile load preferably provides a sufficiently small force that does not extend the heater wire material and does not reduce the diameter of the heater wire material. After completion of the bending, the heater wire material 1 is cut so as to have a semicircular shape, and the end surface 4 is polished to be perpendicular to the tangent to the semicircle, so that the semicircular member 11 is formed. Although the number of joints increases in the post-treatment bonding process, it is also natural that other shapes such as 1/3 circular or 1/4 circular shapes that are not larger than the semicircular shape can be used.

[3] production of coil heaters

The coil heater is produced by diffusion bonding between the semicircular members (11). 2 schematically shows a production process of a coil heater by diffusion bonding. With respect to the diffusion bonding, a place close to the end face 4 of the semicircular member 11 is fixed by the clamping portion 6 so that the place can be pushed perpendicularly to the respective bonding surfaces, It can be pressed in the tangential direction of the joint. While the predetermined pressure is applied on each bonding surface 4 through the clamping portion 6, the bonding surface 4 is supplied with electricity and pressure at a high temperature so that each bonding 5 is formed by welding do. The clamp portion 6 is designed to fix the semicircular member 11 having a curvature, and is selected according to the curvature of the coil. Each time the coupling is completed by a half turn, the semicircular members 11 are moved while being shifted by a predetermined pitch. When the coil heater with a predetermined number of turns is completed, the terminals are coupled to both end portions of the coil heater by a diffusion bonding or the like.

In the present invention, the coil inner diameter D and the heater-to-heater distance t in the coil heater satisfy a relationship of 0.9? T / (D / 2) ^1/2? 4.0. Here, the heater-to-heater distance t is defined as the distance between the adjacent heaters of the coil (i.e., the distance between adjacent coils of the helix). If t / (D / 2) < ^1/2 > is less than 0.9, the strain is undesirably large. If t / (D / 2) < ^{1/2 >} is greater than 4.0, temperature uniformity is undesirably lowered besides the increase in strain. It is preferable that 0.9? T / (D / 2) ^1/2? 4.0.

One side of each terminal is machined to have the same diameter as the heater wire material so as to be able to engage the heater wire material. Further, it is preferable to bend the terminal in an L shape so that the other side of the terminal is exposed to the outside from the ceramic mold.

[4] ceramic molds

The thermal insulation material used in the tubular heater module according to the present invention is a tubular ceramic mold. The alumina material having high heat resistance is preferable as the material of the tubular ceramic mold. Although heat-resistant heaters generally expand during heating and shrink during cooling, wire breakage can often be caused by abnormal heating due to local deformation when expansion / contraction is limited. Thus, the idea to avoid limiting expansion / contraction is to place a MoSi ₂ - system coil heater in the mold. In this regard, the MoSi ₂ -based heater according to the background art is U-shaped and adopts a method of hanging a MoSi ₂ -based heater by a staple. 3 showing a part of a section of the tubular heater module according to the present invention, the MoSi ₂ -type coil heater 21 is arranged in a free state in the coil-shaped groove 31 formed in the ceramic mold 30. [ I.e., MoSi ₂ - Fig type heater coil 21 is even and is supported by a respective one side of the groove, MoSi ₂ - type heater coil 21 can move freely over the grooves without projecting to the outside of the groove. For this reason, each of the inner surface of the groove 31 in the ceramic mold is MoSi ₂ - has a sufficient hardness to not strain showed a slight reaction to the series coil heater (21). Regarding the size of each of the grooves, the groove has a width and depth sufficient to prevent the MoSi ₂ - system coil heater 21 from being restricted. Although not shown in the figures, the staple may be installed across some grooves to prevent the MoSi ₂ -type coil heater from protruding out of the groove 31.

Example

Example 1

MoSi ₂ having an average particle size of 2.7 μm was mixed with 15% by volume of bentonite and a predetermined amount of water and stirred to obtain a molding green body. Further, the obtained clay was molded into 3.4 mmΦ and 6.8 mnmΦ rod using an extrusion molding apparatus. The rod was cut to a length of 800 mm. After drying, the rods were sintered at 1500 DEG C for 2 hours under a nitrogen atmosphere to obtain a sintered compact of about 3 mm in diameter and about 6 mm in diameter. Both ends of a pseudo-semicircular intermediate member having an internal diameter of 300 mm are clamped and a compact sintered in a 3 mm x 700 mm rod according to the method shown in Figs. 1a, 1b and 1c is bent (Bending temperature: 1450 DEG C). The intermediate member was cut in a semicircular shape, and the two cut surfaces of the intermediate member were polished to be one plane. A semi-circular member such as a coil having a pitch (P) of 23 mm was joined by butt resistance welding according to the method shown in Fig. We produced a coil heater with 20 revolutions from 40 semicircular members. In addition, a terminal produced by machining was bonded to both ends from a compact sintered in a rod shape of 6 mmΦ. A pair of semi-cylindrical ceramic molds with an inner diameter of 294 mm, an outer diameter of 460 mm and a height of 500 mm were formed with grooves having a width of 6 mm and a depth of 10 mm at a pitch (P) of 23 mm. A coil heater with 20 rotations inside the groove in one semi-cylindrical ceramic mold was set to be fully positioned. Another semi-cylindrical ceramic mold was placed thereon. Bonded surfaces of the molds were bonded to each other by a heat-resistant ceramic adhesive. However, the groove through which the terminal passes is processed at the joint surface of the mold.

<Measurement of Temperature Distribution>

An alumina heat-insulative material having a thickness of 100 mm was placed on the bottom (bottom) and top (lid) of the manufactured tubular heater module and a thermocouple B for controlling the temperature of the heater module was placed on the bottom And was set at a position 10 mm away from the inner circumferential surface in the center direction and at a position 250 mm away from the lid portion. The temperature of the heater module was set to 1500 ° C. and the other thermocouple B for measuring the temperature distribution was positioned 50 mm away from the inner circumferential surface of the heater module and 100 mm away from the cover and 100 mm The measurement of the temperature distribution was performed under the condition set at a range of 300 mm between the distant positions. The temperature slightly changed depending on the position with respect to the coil, and the temperature difference ΔT between the maximum and minimum of the temperature was not larger than 3 ° C.

<Life test>

In the life test of the heater module, the temperature was varied from room temperature to 1500 占 폚. The pattern was maintained at a temperature of 1500 DEG C for one hour and then cooled to room temperature. This pattern was repeated 500 times. I could not observe a special change in the coil heater. There was no wire destruction. As shown in Fig. 4, it was confirmed whether a change was observed based on the positional relation of the coil heater after the test on the heater groove of the mold. If there is any place where the cross section of the heater protrudes inward from the inner circumferential end of the heater groove past the semicircular region, it is determined that deformation exists.

Examples 2 to 16 and Comparative Examples 1 to 6

The heater-to-heater distance t for each coil inner diameter D is set to the respective distance shown in Table 1, the wire diameter of the heater wire material is still set to 3 mm, and the coil inner diameter ( D) was set to 300 mm, 600 mm, and 900 mm in each of the examples shown in Table 1, the coil heater and the cylindrical heater module were produced. With respect to the size of each of the ceramic molds, the inner diameter and the outer diameter corresponding to the inner diameter of the coil were set, but the height was set to 500 mm in all embodiments. Therefore, the number of rotations was set to a number corresponding to the inter-heater distance t. As in Example 1, in each of the embodiments, a groove having a width of 6 mm and a depth of 10 mm was formed in a pair of semi-cylindrical ceramic molds, and these grooves were formed in a case where the interheater distance t was 10 (P) spacing of 13 mm, a pitch (p) spacing of 23 mm when the heater-to-heater distance t is 20, a pitch p spacing of 33 mm when the heater- (P) interval of 43 mm when the heater-to-heater distance t is 40, a pitch (p) interval of 53 mm when the heater-to-heater distance t is 50, (P) spacing of 63 mm, a pitch (p) spacing of 73 mm when the heater-to-heater distance (t) is 70, a pitch (p) spacing of 83 mm when the heater- And a pitch (p) of 93 mm when the distance t between the heaters was 90 degrees. For each example and each comparative example, the temperature distribution was measured in the same manner as in Example 1, and the life test was further performed. The results, including the results in Example 1, are shown in Table 1. Here, in the result of the temperature distribution, when the temperature distribution was not larger than 3 ° C, it was evaluated as OO . When the temperature distribution was larger than 3 ° C but not larger than 5 ° C, it was evaluated as O , In the large case, it was evaluated as x. In the results of the life test, the above-mentioned case without deformation was evaluated as O , and when there was deformation, x was evaluated. In the overall evaluation, when either the result of the temperature distribution or the result of the life test was x, the result was evaluated as x, the result of the temperature distribution and the result of the life test were evaluated as O in the case of O , When the result was OO , it was evaluated as OO .

Inner diameter
(D, mm) Heater Interval
(t, mm) t / (D / 2) ^1/2 Temperature distribution Accelerated life test Overall assessment Example 1 300 20 1.6 OO O OO Example 2 300 30 2.4 OO O OO Example 3 300 40 3.3 O O O Example 4 600 20 1.2 OO O OO Example 5 600 30 1.7 OO O OO Example 6 600 40 2.3 OO O OO Example 7 600 50 2.9 OO O OO Example 8 600 60 3.5 O O O Example 9 600 70 4 O O O Example 10 900 20 0.9 OO O OO Example 11 900 30 1.4 OO O OO Example 12 900 40 1.9 OO O OO Example 13 900 50 2.4 OO O OO Example 14 900 60 2.8 OO O OO Example 15 900 70 3.3 O O O Example 16 900 80 3.8 O O O Comparative Example 1 300 10 0.8 O x x Comparative Example 2 300 50 4.1 x x x Comparative Example 3 600 10 0.6 O x x Comparative Example 4 600 80 4.6 x x x Comparative Example 5 900 10 0.5 O x x Comparative Example 6 900 90 4.2 x x x

When t / (D / 2) ^1/2 was less than 0.9, the temperature distribution was good, but deformation still occurred. If t / (D / 2) &lt; ^{1/2 &gt;} is greater than 4.0, the temperature distribution and deformation are consequently undesirable. ^{t / (D / 2) 1} / 2, if is in the range of 0.2 to 2.9, in particular to obtain the desired results.

Claims (5)

In a tubular heater module in which a MoSi ₂ - system coil heater is disposed in a coil-shaped groove formed in an inner circumference of a ceramic mold, the MoSi ₂ system coil heater has an inner diameter D of the coil of 300 mm or less, Wherein the inner diameter (D) and the heater-to-heater distance (t) of the tubular heater module satisfy the following condition:
0.9? T / (D / 2) ^1/2? 4.0. delete delete delete delete

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