JP2000344580A - Sagger for firing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce thermal stress which occurs at the time of heating, firing and cooling, to prevent the formation of strain, cracks or the like and to realize long life by separating a sagger into a frame body part and a bottom plate part which protrudes from the periphery of the frame body part and is made of a ceramics having high thermal conductivity. SOLUTION: Saggers, each being composed of a frame body 1 and a bottom plate 2 are piled up to the required number of steps and matters to be fired are put on each bottom plate 2. Thereafter, the saggers are introduced into a continuous-of batch-type furnace and the matters to be fired are fired. These saggers are each made a separated structure that the frame body 1 is separated from the bottom plate 2. Further, the bottom plate 2 extrudes by a prescribed width α, e.g. about 5 to 50 mm, from the periphery of the frame body 1, and projecting parts, notched parts or the like which fit with the lower part of the frame body 1 are optionally provided. Further, it is preferable that the bottom plate 2 is formed using a highly thermal-conductive ceramic such as Al2O3 and, if necessary, the upper face or the lower face of the bottom plate 2 is laminated with a metal plate, thereby the time for firing the matter to be fired can be shortened and thermal stress is further reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a firing sagger, and more particularly, to a firing sagger having a long life, which reduces thermal stress generated during heating, firing or cooling, and eliminates distortion, cracks and the like.

[0002]

2. Description of the Related Art A baking sagger used in a powder baking or a powder reaction process is made of, for example, ceramic and has a thick plate structure capable of withstanding a load during handling. As a characteristic required for such a firing sagger,
For example, it does not react with the material to be fired, has thermal shock resistance, and has good heat transfer characteristics in a heating furnace. As a conventional technique for satisfying the above characteristics, for example, a sagger in which a low-reaction setter is arranged at the bottom of an integrated sagger having excellent thermal shock resistance (Japanese Patent Laid-Open No. 8-8 / 1996).
As a conventional technique for satisfying the characteristics of, for example, a bottom portion and an edge portion (frame portion) of an integrated sagger
There is a sagger (Japanese Unexamined Patent Publication No. Hei 4-280874) in which the particle size of the constituent materials is changed. As a conventional technique for satisfying the characteristics of, for example, a bottom part and a frame part are separately manufactured, and these are combined. There is an integral type sagger bonded in an H-shape (Japanese Utility Model Laid-Open No. 28399/1985).

On the other hand, there has been proposed a sagger for firing a ceramic product in which a plate member and a frame member are divided so as to enhance the convenience of the sagger. FIG. 5 is an explanatory view showing a cross section of such a conventional firing sagger. In the figure, this sagger 1
1 is a plate member 12 on which an object to be fired is placed;
And a frame member 13 supporting the outer edge portion of the frame member with a groove 14 provided along the inner periphery. The object to be fired is placed on the plate member 12, introduced into, for example, a tunnel pusher furnace or the like, and fired at a predetermined temperature.

[0004]

However, the above-mentioned conventional firing sagger is essentially of an integral structure, and the thermal stress generated during heating and cooling is particularly large at the bottom plate portion.
There is a problem that the life is short, such as cracks occurring in a short period of time. Further, FIG. 5 in which the plate member and the frame member are separated.
The sagger is excellent in convenience because only the plate members need to be replaced each time the size and shape of the material to be fired are different, but the heat input (heat transfer) part in the firing process Is only a frame member and there is no direct heat input to the bottom plate portion, so that the heat transfer efficiency is not always good. In addition,
In the sagger of FIG. 5, no improvement has been made from the viewpoint of reducing the thermal stress, and the technique for extending the life of the sagger has not been sufficient. An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a long-life sagger for firing that reduces generated thermal stress and eliminates distortion, cracks and the like.

[0005]

The invention claimed in the present application to solve the above-mentioned problems is as follows. (1) A firing sagger having a bottom plate portion and a frame portion, wherein the bottom plate portion and the frame portion have a separated structure, and the frame portion is mounted on the bottom plate portion. Bowls. (2) The firing sagger according to (1) above, wherein the bottom plate portion protrudes from the outer peripheral end of the frame portion by a predetermined dimension.

(3) The above (1) or (2), wherein the bottom plate portion is formed of a high thermal conductivity ceramic.
The firing sagger according to 1. (3) The firing sagger according to (3), wherein a metal plate is laminated on an upper surface or a lower surface of the high thermal conductivity ceramic molded body. The firing sagger is a box used for firing an object to be fired, and includes a bottom plate portion and a frame portion forming a space with a predetermined capacity on the bottom plate portion.

[0007]

FIG. 1 is a sectional view of a firing sagger showing an embodiment of the present invention. In the figure, two saggers are stacked, and this sagger has a separation structure in which a frame portion and a bottom plate portion are separated, and a frame 1 as a frame portion is placed on a bottom plate 2 as a bottom plate portion. The bottom plate 2 protrudes from the outer peripheral end of the frame 1 by a predetermined dimension α. The object to be fired is stored or filled in the firing sagger having such a configuration, and the temperature in the furnace is adjusted to, for example, 800 to 1000 ° C., introduced into a continuous or batch-type heating furnace, and the object to be fired is Fired.

According to this embodiment, since the frame 1 and the bottom plate 2 are separated to have a separated structure, they appear most at the joint between the bottom plate and the frame in a conventional integrated sagger. Since the thermal stress can be reduced to about 2/3, cracks and the like are prevented, and the sagger life is extended. Further, since the bottom plate 2 protrudes from the outer peripheral end of the frame 1 by a predetermined dimension α, the bottom plate 2 is directly heated by the heating means provided on, for example, the side surface of the heating furnace, similarly to the frame 1. As a result, the temperature gradient of the entire sagger becomes small, the thermal stress is reduced, and the life is prolonged. In this embodiment, the size α of the bottom plate 2 protruding from the outer peripheral end of the frame 1 is determined by the size of the sagger, required handling characteristics, and the like, and is, for example, 5 to 50 mm.

In this embodiment, both the frame 1 and the bottom plate 2 are made of a ceramic material such as brick, alumina, silica, magnesia and the like. The size of the bottom plate 2 is, for example, 250 to 350 mm long × 250 to 350 mm wide and 3 to 20 mm thick. The height of the frame 1 is, for example, 50 to
100 mm, thickness is 3-20 mm. The shape of the frame is not limited to a quadrangle in a plan view, but may be a circle or an ellipse, and a hole or a notch for venting gas may be provided in a part of the frame 1. In the present embodiment, the firing sagger is used as one stage or by laminating two or more stages.

In the present embodiment, the bottom plate 2 is, for example, 9
It is preferable to use a high thermal conductivity ceramic such as 9.9% -Al ₂ O ₃ . Thereby, the heat transfer efficiency is improved, and not only the firing time of the object to be fired can be shortened, but also the thermal stress is reduced and the life is further extended. By forming only the bottom plate 2 in which large thermal stress is easily generated from high thermal conductivity ceramic, a sagger that is relatively inexpensive, has excellent durability, and has a long life can be obtained. When only the bottom plate 2 is consumed, only the bottom plate needs to be replaced, so that the cost can be reduced as compared with the conventional integrated sagger. In this embodiment, the shape of the bottom plate 2 may be a flat plate as shown in FIG. 1, but as shown in FIG. 2 for the purpose of positioning the frame 1 and fixing the frame during setting and handling. Alternatively, a projection 5 may be provided on the periphery. In addition, as shown in FIG. 3, the frame 1 may be provided with a notch 6 to be fitted with the projection 5 of the bottom plate 2.

FIG. 4 is a sectional view showing another embodiment of the present invention. In the figure, this sagger differs from the sagger of FIG. 1 in that a plate made of a high thermal conductivity ceramic molded body is used as a bottom plate 2, a metal plate 3 is laminated on a lower surface of the bottom plate 2, and a frame 1 is formed. Is that the lid 4 made of the same material as the bottom plate 2 is placed on the upper part. According to the present embodiment, the bottom plate 2
By using a ceramic body having a high thermal conductivity and laminating a metal plate on its lower surface, the heat transfer surface is increased, and the thermal stress during firing or cooling is extremely reduced, so that the life of the sagger is significantly prolonged. In this embodiment,
The frame 1 may be provided with holes for degassing. When two or more saggers are stacked, it is preferable to place the metal plate 3 on the upper side surface of the lid 4 of the uppermost sagger. Thereby, the heat transfer efficiency is further improved.

In this embodiment, the bottom plate 2 made of a ceramic body having a high thermal conductivity functions as a setter, and the metal plate 3 functions as a reinforcing material or a jig for handling by a robot or the like. The constituent material of the setter is selected so as not to react with the object to be fired, and as the metal plate material, for example, carbon steel, stainless steel, heat-resistant alloy, or the like is used.

[0013]

Next, specific embodiments of the present invention will be described. Example 1 porosity 27%, bending strength at room temperature 10 MPa, the thermal conductivity of _{1.8kcal / mhK, 50% Al 2} O 3 -4
Vertical 320mm × horizontal 320mm consisting 6% SiO ₂ -MgO
× A plate-like molded body having a thickness of 16 mm is used as a bottom plate, and is made of the same material as the bottom plate and has a height of 50 mm, a width of 300 mm and a thickness of 16 mm.
A square frame on a plan view was placed on the bottom plate to form a separate sagger. Three sets of these separated saggers were prepared, each of which was filled with a powder to be a raw material of lithium cobaltate as an object to be fired, introduced into a tunnel pusher furnace adjusted to 800 to 1000 ° C., and fired. When the thermal stress generated in the sagger at this time was analyzed by the finite element method, the maximum stress was generated near the center of the bottom plate during the heating process, and the value was 3
The pressure was 5 MPa, and it was generated at the outer peripheral portion of the bottom plate during the cooling process, and the value was 70 MPa. Further, the same firing test was repeated a plurality of times, and the number of firings (life) until the sagger, specifically, the bottom plate was damaged, was measured. As a result, the average of three sets was 52 times.

Example 2 The bottom plate was made of a ceramic having a high thermal conductivity, a porosity of 2% or less, a bending strength at room temperature of 200 MPa, and a thermal conductivity of 3
A separate sagger was formed in the same manner as in Example 1 except that a plate-shaped molded body of 99.9% Al ₂ O ₃ of 0.2 kcal / mhK was obtained, and a similar firing test was performed. When the stress analysis and the number of repeated firings before breakage were measured, the maximum thermal stress was generated during the cooling process, and the value was 35 M
At Pa, the three separate saggers were fired 200 times, but none of them was damaged.

COMPARATIVE EXAMPLE 1 A bottom plate and a frame were integrally formed using the same material as in Example 1 to form a sagger, and the same firing test as in Example 1 was conducted. When the number of repetitive firings was measured, the maximum thermal stress was 100 MPa, and the number of repetitive firings before breakage was 20 on average for three sets of saggers.

Tables 1 and 2 show the shapes of the saggers and the physical properties of the components in Examples 1 and 2 and Comparative Example 1, and Table 2 shows the firing test results.

[0017]

[Table 1]

[0018]

[Table 2] In Table 2, in the sagger of Example 1 in which the frame body and the bottom plate were separated, the maximum thermal stress was reduced by 30% as compared with the sagger of Comparative Example 1 in which the constituent materials were the same, and the life was shortened. It can be seen that was extended. Further, it can be seen that in Example 2 in which the bottom plate was formed of a ceramic having high thermal conductivity and high strength, the maximum thermal stress was reduced to half or less, and the life was extended ten times or more.

[0019]

According to the invention described in claim 1 of the present application,
The thermal stress generated at the time of firing is reduced, and the life of the sagger can be extended. According to the invention described in claim 2 of the present application, not only the frame body but also the bottom plate portion serves as a heat transfer portion. In addition to the effects of the above invention, the temperature gradient of the entire sagger becomes smaller, Life is extended.

According to the invention of claim 3 of the present application, in addition to the effects of the above-mentioned invention, the firing time of the object to be fired can be shortened, and the life is further extended. According to the invention described in claim 4 of the present application, in addition to the effects of the above invention, the heat transfer surface is increased and the heat transfer efficiency is improved, so that the thermal stress can be further reduced and the life of the sagger can be significantly extended. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a separation type sagger showing one embodiment of the present invention.

FIG. 2 is a diagram showing another embodiment in one embodiment of the present invention.

FIG. 3 is a view showing still another embodiment in one embodiment of the present invention.

FIG. 4 is an explanatory view showing another embodiment of the present invention.

FIG. 5 is an explanatory view showing a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Frame, 2 ... Bottom plate (bottom plate made of high thermal conductivity ceramic molding), 3 ... Metal plate, 4 ... Lid body made of high thermal conductivity ceramic molding, 5 ... Projection, 6 ... Notch.

Continued on the front page (72) Inventor Kazuo Abe 5-6-4 Tsukiji, Chuo-ku, Tokyo Mitsui Engineering Shipbuilding Co., Ltd. (72) Inventor Zenji Kamio 1 Yawata Kaigandori, Ichihara City, Chiba Prefecture In-house (72) Inventor Naoki Hatta 1 Yawata Kaigandori, Ichihara-shi, Chiba Mitsui Engineering & Shipbuilding Co., Ltd. Chiba Works F-term (reference) 4K018 DA38 4K055 AA08 HA02 HA08 HA12 HA18 HA27

Claims (4)

[Claims] 1. A firing sagger having a frame portion and a bottom plate portion, wherein the frame portion and the bottom plate portion are separated from each other, and the frame portion is mounted on the bottom plate portion. Sagger. 2. The apparatus according to claim 1, wherein the bottom plate protrudes from the outer peripheral end of the frame by a predetermined dimension.
The firing sagger according to 1. 3. The firing sagger according to claim 1, wherein the bottom plate portion is formed of a high thermal conductivity ceramic. 4. The firing sagger according to claim 3, wherein a metal plate is laminated on an upper surface or a lower surface of the high thermal conductivity ceramic molded body.