JPH02153864A - Calcination of silicon carbide board - Google Patents

Abstract

PURPOSE:To prevent deformation such as damage, warpage or bending of materials to be calcined and to obtain SiC board having excellent flatness of board face by sandwiching given sheets of board materials to be calcined made of SiC in between carbon plates, standing, arranging and calcining the board materials while arranging carbon plates in a state of standing at both sides of the board materials. CONSTITUTION:A great number of sheets of materials 11 to be calcined made of SiC are sandwiched in between a great number of sheets of carbon plates 12, arranged in a standing state on the bottom in a carbon calcining furnace 15 and carbon plates 13 are laid at both sides of these boards. Further fixing blocks 14 are arranged at both sides of the carbon plates 13. Then in this state, the materials 11 to be calcined are heated up to 2,400 deg.C in an inert gas atmosphere such as Ar gas and calcined. In the operation, since the materials 11 to be calcined are vertically arranged, excessive load will not act on part of the materials 11 to be calcined as it is different from a conventional method of piling a great number of materials to be calcined. Consequently, cracking, warpage on the surface, bending, etc., of the materials 11 to be calcined can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for firing a silicon carbide plate used for a shelf board or the like used for firing ceramic parts such as an IC board.

(Prior Art) Silicon carbide (S i C) plates, especially high-purity recrystallized silicon carbide fired products that do not contain binders, are used in high-temperature fields, such as shelf boards for firing alumina EC boards. This product can withstand long-term use even at high temperatures of approximately 1,600°C, has excellent mechanical strength even though it is thin, and has many features such as being resistant to heat Fi8j N caused by rapid heating and cooling. . In addition, particularly for those used as shelf boards, it is desired that the board surface be flat in order to prevent thermal deformation of the placed object (alumina IC board) during firing.

The following methods are known as methods for firing this type of silicon carbide plate. First, the abrasive material is formed into a thin plate by press molding or casting and dried. Then, these items to be fired are lined up in a carbon matsufuru with a space between them, and placed on the top end while engaging a spacer bar with a spacing of 19 rivers, similar to firing tiles. There is a method in which the products to be fired are held in a standing arrangement and heated in an argon gas atmosphere. However, with this method, it is difficult to hold the fired product vertically, so the tilted fired product often bends and deforms due to its own weight during firing, making it difficult to maintain flatness. In some cases, the product was considered defective. For this reason, in recent years, as shown in Fig. 2, a base plate 2 with a flat surface is placed inside the carbon pine full 1, and the base plate There is also a method in which a large number of articles 3 to be fired are piled up and housed on the holder 2, and the articles 3 are fired by heating to about 2400° C. in an argon gas atmosphere. This is intended to prevent deformation such as bending or warping during heating by overlapping the masks of the product to be fired 3 in a tight manner, and to ensure the flatness of the plate surface of the product to be fired.

(Problem to be Solved by the Invention) However, although the plate surface of the product to be fired 3 is formed to be flat, there are slight variations in the plate thickness depending on the position within the plane. As shown in Figure 2, there may be gaps between the stacked objects to be fired and the earthen floor. Then, the heated and softened product 3 bends downward and deforms due to its own weight and the load from above, following the plate surface of the product 3 located below. This deformation becomes more severe as gaps accumulate over a large number of sheets, so if flatness is strictly required, the sheet may be rejected as a defective product.

In addition, since the unfired product 3 that does not contain a binder is relatively fragile, the conventional firing method of stacking a large number of sheets has the disadvantage that excessive weight acts on the product 3, causing damage to the product. Ta.

Furthermore, although moisture has been removed from the fired product 3 during drying, since the kiln filling operation is performed in the atmospheric atmosphere 11, moisture in the atmosphere is adsorbed onto the surface. For this reason, in the conventional method of stacking the products 3 to be fired in multiple stages,
Since a large load is applied from above to the products to be fired 3 located in the lower stage, they may adhere to each other due to the influence of moisture adsorbed on the surface. If these fired products are separated after firing, the products are likely to be damaged or chipped. This drawback can be overcome, for example, by interposing a thin plate-shaped spacer having a surface dimension equal to or larger than that of the products to be fired 3 between each of the products to be fired. The problem of cracks in the fired product 3 still remains.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to create a silicon carbide plate that can prevent damage to the fired product and deformation such as warping as much as possible, and improve the flatness of the plate surface of the fired product. The firing method is explained below.

[Structure of the Invention] (Means for Solving the Problems) The method for firing silicon carbide plates of the present invention includes arranging a predetermined number of products to be fired with carbon plates sandwiched between them in a firing furnace, Characteristic H is where carbon plates are placed on both sides of these.

(Function) According to the above method, since it is easy to support each article to be fired so that it stands vertically, there is no possibility that bending deformation force acts on the article to be fired, resulting in thermal deformation. In addition, unlike when products to be fired are stacked in multiple stages, excessive loads are not applied to some products to be fired, which prevents cracks from occurring, and even if moisture is adsorbed on the board surface. Also, the plate surfaces do not come into strong contact with each other during firing. Moreover, even if the product to be fired has some warpage or variation in thickness due to drying, the carbon plates are sandwiched between a predetermined number of sheets, so carbon plates with good flatness and little thermal deformation can be used as separations. Since deformation is suppressed, large deformation will not occur.

In this case, carbon plates are used because carbon has good thermal conductivity and is not only resistant to rapid heating and cooling, but also has sufficient strength even at high temperatures of, for example, 2500°C in a non-oxidizing atmosphere. This is because it does not react with R silicon carbide.

(Example) An example of the present invention will be described below with reference to FIG.

This figure 1 shows the state during firing, and here, 11
is a fired product fired by the method of the present invention. This product 11 to be fired is fired as a shelf board used in a high/H firing kiln, for example, and is made of silicon carbide and has, for example, a board surface size of 280 mm x 33C1n and a thickness of 6.5 mm.
It is molded into a plate shape of mm by casting. 12 is a carbon plate sandwiched between the products 11 to be fired;
It has the same plate surface dimensions as the above-mentioned fired product 11, and the plate surface is formed flat by machining. Reference numeral 13 denotes a carbon plate disposed on both sides of the product to be fired 11, and the plate surface is formed flat like the carbon plate 12, and has the same plate surface χJ method as the product to be fired 11. It is formed with a thickness greater than 12 (for example, 15 mm). A fixing block 14 is made of carbon, for example, and is designed to have sufficient weight and size to support the product 11 during firing, which will be described later. Reference numeral 15 denotes a carbon matsuffle serving as a firing furnace (only the bottom part is shown), and the inside thereof is set to have an inert gas atmosphere, such as argon gas, during firing.

Next, a procedure for firing the article to be fired 11 will be explained. First, a large number of articles 11 to be fired are housed in the carbon pine full 15 in a state as shown in FIG. That is, a large number (for example, 20 to 30) of the products 11 to be fired are arranged upright on the inner bottom surface of the carbon pine full 15 with a carbon plate 12 sandwiched between a predetermined number of pieces, for example, every four pieces. At the same time, carbon plates 13 are placed on both ends of the products to be fired 11 arranged side by side. At this time, these fired products 11, carbon plate 12
The carbon plates 1'3 are arranged so that the edge portions are parallel to each other and the plate surfaces are in close contact with each other. Further, fixing blocks] 4 are placed on both sides of the carbon plate 13.13. This fixing block 14 plays the role of supporting the objects to be fired 1 and the carbon plates 12 and 13 that are lined upright so that they do not fall down, and is placed so as to press against the carbon plates 13, so that the objects to be fired can be The entire article 11 is held in a vertical position by being sandwiched from both sides, and the adhesion between the surfaces of the plates is improved. In this case, since the individual products 11 to be fired are not separated from each other and made to stand on their own, it is easy to support the products 11 to be fired so that they stand vertically. After storing the article 11 to be fired in the carbon matsful 15 as described above, the article 1 to be fired is heated to
Heat to 'C and bake.

According to this embodiment, the products to be fired 11 are arranged vertically, so unlike the conventional method in which products to be fired are stacked in multiple stages, an excessive load is applied to some of the products to be fired 11. Things will disappear. Therefore, the occurrence of cracks in the product 11 to be fired can be prevented, and even if moisture is adsorbed on the surface of the product 11 to be fired when it is packed in the kiln, the surfaces of the product 11 to be fired can be strongly bonded together during firing. Since they are no longer glued together, there is no problem of chipping or damage when separating them.

Even if the thickness of the fired products 11 varies depending on the in-plane position, or warping occurs during drying, and gaps are created between the fired products 11 when packed in the kiln, the carbon plates 12 are inserted between every four sheets. Since the carbon plate 12 acts as a partition, no accumulation of gaps occurs, and thermal deformation of the fired product 11 during firing is also corrected. As a result,
Unlike the conventional method of arranging them with gaps between them, which allows free bending and deformation, deformation such as warping can be prevented as much as possible, and even if deformation such as warping occurs, it will be extremely small. You can get away with it. By the way, place the fired product (shelf board) on the reference surface, measure the height dimension from the hard surface for a 30 cm diagonal of the board surface, and calculate the difference a between the maximum value and the minimum j-direction, ? , 'J bell warpage inspection,
In contrast to the baked products produced by the conventional method where α was within 0.4+am as acceptable products, the fired products according to the present example achieved good results in that α was suppressed to within 0°2■. As described above, in the firing method of this embodiment, damage such as cracks, chips, etc., and deformation such as curvature of the fired product 11 can be prevented as much as possible, and the flatness of the plate surface of the fired product can be improved. It is something.

In the above embodiment, the plate surface τj method of the carbon plate 12 is the same as that of the product to be fired 11;
A similar effect can be obtained if there is a Judiciary with a height of /3 or higher. In addition, there is no particular limit to the thickness of the carbon plate]2, but
Practically speaking, the thickness is preferably about 1/2 to 3 times the thickness of the product to be fired 1]. Furthermore, the carbon plates are not limited to the method of sandwiching the products to be fired every four pieces, but may also be sandwiched one by one, or the number of pieces to be fired can be sandwiched between carbon plates with various holes. The number may be set as a predetermined number in consideration of the flat surface accuracy and the carbon plate thickness.

In addition, the fixing block may be made of silicon carbide or the like as long as it does not cause thermal deformation or reaction in the firing temperature atmosphere.The present invention can be modified in various ways.

[Effects of the Invention] As is clear from the above explanation, according to the method for firing a hardened silicon plate of the present invention, a predetermined number of products to be fired are placed in a firing furnace with carbon plates sandwiched between them. Since the carbon plates are placed on both sides, it is possible to prevent as much as possible the products to be fired from sticking together, breakage, or deformation such as bending, and improve the flatness of the plate surface of the fired products. be effective.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the state inside a firing furnace showing an embodiment of the present invention, and FIG. 2 is a diagram corresponding to FIG. 1 showing a conventional example. In the drawing, 11 is a product to be fired, 12.13 is a carbon plate, 1
5 indicates a carbon matsufuru (firing furnace).

Claims (1)

[Claims] 1. A method of firing a large number of plate-shaped products to be fired made of silicon carbide in an inert gas atmosphere, wherein carbon plates are sandwiched between a predetermined number of the products to be fired in a firing furnace. A method for firing silicon carbide plates, characterized by arranging them vertically and placing carbon plates on both sides.