JPH03255887A - Shelf plate for calcination - Google Patents

Abstract

PURPOSE:To improve the stability in various atmospheres and prevent any impurity from entering into a held calcined article by forming a title plate with specific purity aluminum ceramic into a plate-shaped structure of a thick crossectional shape where substantially triangular hollow parts are disposed in parallel. CONSTITUTION:A title shelf plate 1 is yielded by forming successively a molded structure having substantially triangular hollow parts 2 at a thick wall part by a vacuum extrusion molding machine by mixing 99.5% impurity or more aluminum raw material, a binder, a plasticizer, and a lubricant, and by calcining the molded structure. On a calcined article mounting surface of the shelf 1, corrugated fluted/protruded parts 3 are provided to reduce the contact area between those parts and the mounted calcined articles as mush as possible. Since the shelf 1 is constructed with the high purity aluminum ceramic material, heat and erosion resistances of the shelf plate 1 can be improved together with the increased stability at high temperature and in various gas atmospheres, and hence any impurity can be prevented from entering from the shelf plate 1 to the placed calcined article.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a shelf board on which electronic industrial parts and the like are mounted and fired.

[Conventional technology]

Conventionally, alumina refractories with flat mounting surfaces have been used as shelves for firing electronic industrial parts, but the components of the refractories with shelves made of solid boards permeate into the fired products. In order to suppress this effect, a high-purity alumina center is interposed between the shelf board and the loaded fired material, and in addition, bedding powder is dispersed on the setter to prevent the shelf board and the fired material from forming. Prevents contact and fusion with fired products.

[Problem that the invention seeks to solve]

In the above conventional example, when the fired product is placed on a shelf, when exposed to a high-temperature atmosphere such as in a furnace, the components of the shelf-mounted refractory penetrate into the fired product and create impurities. In addition, since the contact area with the loaded object is large, a fusion phenomenon occurs, which tends to cause scratches on the surface of the fired product.

As an improvement to the above method, a method in which a setter is interposed between the shelf board and the fired product and the bedding powder is further dispersed on the center is negligible in cost because high purity is required for the material of the setter. However, since there is a limit to repeated use, there is a lot of waste.

Similarly, there is a limit to the repeated use of bedding powder, and the complicated process of centering the center and dispersing the bedding powder evenly has also been pointed out as a problem, so a shelf as an alternative to the combination of shelf board, cenotar, and bedding powder has been pointed out. A board should be developed.

[Means for solving problems]

In order to solve the above problems, the present invention has a purity of 99.5.
% or more of alumina ceramics, and has a substantially triangular hollow part in which the cross-sectional shapes of the thick portions are arranged in parallel, the fired product is placed on at least one of the upper and lower surfaces of the plate-shaped body. We have developed a baking shelf with uneven parts on the contact surface.

The shelf board (1) for main firing is made of alumina ceramic material with a purity of 99.5% or more, so that the heat resistance and corrosion resistance of the shelf board (1) itself can be improved, and it can be used at high temperatures and in various gas atmospheres. Increased stability with shelves (1)
It is also possible to prevent impurities from entering the fired product.

Moreover, since the baking shelf (1) of the present invention is composed of a plate-like body having a hollow structure (2), it can meet the demand for weight reduction and maintains energy-saving characteristics with a small heat capacity.

Furthermore, the hollow structure (2) has a substantially triangular cross-sectional shape, which increases creep resistance, and since the wall thickness of each part of the shelf board is thinner to form the hollow structure, dense alumina is used as the material. Despite using ceramics, it is hard to break and has great durability against poling.

In other words, the requirements that made it possible to manufacture firing shelves for the first time using high-purity alumina ceramics, which had not been possible in the past, were overcome, namely the material problem of poor spalling resistance due to iron density. This was achieved by replacing it with a structure.

In addition, by providing the corrugated fold uneven portion (3) on the shelf board mounting surface, the contact area with the mounted fired product is reduced, suppressing the phenomenon of fusion between the shelf board and the mounted fired product, and In addition to making it possible to avoid the use of powder, since the uneven portion (3) creates a space between the contact surface with the fired product, the space promotes the degreasing effect of the fired product and improves the quality of the fired product. enhance

Even when the corrugated corrugated grand origin (3) is formed by extrusion molding, the space between the bottom and the loaded fired material promotes degreasing of the fired material, which is advantageous compared to conventional flat shelf boards. becomes.

At first glance, the baking shelf of the present invention seems to have a complicated structure and increase production costs, but it is characterized by a structure that can be extruded, and both the internal hollow structure and the pleated shape of the upper surface can be easily extruded. Manufactured with high precision and low cost.

[Function and Examples]

The function and examples of the baking shelf of the present invention will be described in detail below, but the size, shape, material, purity of the material, shape of irregularities or folds, shape of the hollow part, etc. It goes without saying that the invention is not limited to the examples.

Alumina raw material with a purity of 99.5%, binder, plasticizer,
A mold release agent was mixed and a vacuum extrusion molding machine was used to continuously obtain a molded body of a shelf board (1) having approximately triangular hollow portions (2) arranged in parallel with the thick part, and the molded body was heated at 1650°C. Bake for 2 hours to obtain a shelf board of 260x130x6tw.

On the surface of the final firing shelf that holds the baked goods, there are large corrugated folds (
3) is designed to minimize the contact area with the loaded fired product.

The above shelf board was replaced with a conventional flat plate type alumina refractory shelf board (260
When comparing the properties with that of the new model (X130X10tm), the creep properties were the same, and the shelf weight was reduced by about 40%.

In addition, alumina parts to be fired (alumina 99.5%, size 50 x 80 x 20 B) were fired at 1560°C using the shelf board of the present invention and the conventional flat alumina refractory shelf board.
When the firing was carried out at a temperature of Due to the influence of a certain silica, white spots appeared on the bottom of the fired product, which is the surface that comes in contact with the shelf board, and it was confirmed that it was necessary to use a setter in addition to using a bedding powder.

Table 1 shows a comparison of the characteristics of the above-mentioned shelf board of the present invention and the conventional flat plate type alumina refractory shelf board.

As shown in Table 1, the baking shelf of the present invention exhibits particularly excellent values in apparent porosity and vent amount.

In addition, the vent amount measurement conditions in Table 1 are: span 240 mm;
The load was 500g (φ100mm), the temperature was 1500°C, and the duration was 3 hours.

The cross-sectional shape of the fold-like protrusion (3) in Table 1 may be semi-elliptical, trapezoidal, rectangular, or triangular in addition to the semicircular cross-section of the oral cavity.

〔Effect of the invention〕

Since the baking shelf of the present invention is made of high-purity material, it exhibits good heat resistance and corrosion resistance, and is highly stable in various atmospheres, as well as being able to suppress the intrusion of impurities into the baked products held thereon. .

Further, since the baking shelf of the present invention is composed of a thin plate having a hollow structure, it can meet the demand for weight reduction and maintains energy-saving characteristics with a small heat capacity.

Furthermore, the hollow structure increases the creep resistance, and the thin wall thickness also increases the spalling resistance.

In addition, the irregularities or large folds formed on the upper surface of the shelf board prevent the phenomenon of fusion and avoid the use of bedding powder.

Furthermore, the complexity of the conventional process of centering and uniformly dispersing bedding powder is eliminated, and the furnace filling work can be performed efficiently.

[Brief explanation of drawings]

FIG. 1 shows an external view of the baking shelf of the present invention. (1) Shelf board for firing (2) Hollow part (3) Grand opening of folds

Claims (1)

[Claims] Made of alumina ceramics with a purity of over 99.5%,
A plate-like body having a substantially triangular hollow part with parallel cross-sectional shapes of the thick parts, and having an uneven part on at least one of the upper and lower surfaces of the plate-like body, on the contact surface with the fired product to be mounted. A shelf board for firing characterized by having a shape.