JPH06191926A - Magnesia ceramic composition - Google Patents

Abstract

PURPOSE:To improve thermal shock strength and flexural strength of a magnesia ceramic composition without causing adhesion of the product by including MgO, Al2O3 and ZrO2. CONSTITUTION:A magnesia ceramic composition consisting of 90-98wt.% MgO obtained by calcining Mg(OH) or by crushing electrofused magnesia, 1-10wt.% Al2O3 and 0.5-10wt.% Zr is mixed with a solvent, a dispersing agent and a binder to afford a slip. This slip is granulated by a spray drier and then, the resultant granules are subjected to press molding in a prescribed form under 800-1000kg/cm<2>. The resultant moldings are burned at 1400-1450 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a magnesia porcelain composition for a kiln tool used for firing electronic parts and the like.

[0002]

2. Description of the Related Art In recent years, with the development of the electronic industry, electronic parts having a wide variety of characteristics have been produced. Among them, electric functional ceramics containing lead oxide are increasing steadily. There is. Conventionally, electrically functional ceramics containing lead oxide have been fired in an alumina-based porcelain kiln tool, but in such an alumina-based porcelain kiln tool, the kiln tool and lead oxide react with each other to reduce product yield. Or
There were problems such as damage to the kiln tools.

For this reason, magnesia porcelain, which is hard to react with lead oxide, has come to be used. However, magnesia porcelain has a problem that it has a large coefficient of thermal expansion and weak thermal shock resistance.

In Japanese Patent Laid-Open No. 63-210061, in order to improve the problems of the above magnesia porcelain,
It is disclosed that 5 to 40% by weight of alumina is added to magnesia to improve thermal shock strength. However, the actual firing temperature is required to be 1500 ° C. or higher, which is problematic in terms of energy saving and cost.

An object of the present invention is to provide a magnesia porcelain composition for a kiln tool which improves the thermal shock strength of the magnesia porcelain and is porcelained at a low firing temperature of 1400 to 1450 ° C.

[0006]

According to the present invention, in a magnesia porcelain composition for a kiln tool, MgO; 90 to 98
% By weight, Al ₂ O ₃ ; 1-10% by weight, ZrO ₂ ; 0.5
The above-mentioned problems are solved by a magnesia porcelain composition containing 10 to 10% by weight.

The reasons for limiting the components of the present invention are as follows. First, if the amount of alumina is less than 1% by weight, sufficient thermal shock strength cannot be obtained, and if it exceeds 10% by weight, the sinterability deteriorates, and in order to completely porcelain,
It requires a high temperature of 1500 ° C or higher. 10 alumina
If it exceeds 5% by weight, reaction with the product occurs and the defective rate increases. Further, if the amount of zirconia is less than 0.5% by weight, a high temperature of 1500 ° C. or higher is required to completely make it porcelain, and if it exceeds 10% by weight, the thermal shock strength is lowered.

Since the magnesia porcelain according to the present invention has the above-mentioned structure, it does not cause a reaction such as sticking with a product as a kiln tool for electronic parts containing a large amount of lead oxide, and has a conventional thermal shock strength. Since it is superior to the above, the firing time of electronic parts can be shortened as compared with the past.

For firing a kiln tool using the magnesia porcelain composition of the present invention, for example, the following methods are available. Magnesia powder made by calcining magnesium hydroxide at a predetermined temperature, or magnesia powder obtained by crushing electrofused magnesia, alumina and zirconia are compounded to a predetermined composition, and a solvent is added to this. As an alcohol, a dispersant and a binder are added and mixed by a ball mill. Next, the obtained slip is granulated with a spray dryer,
Press-molded into a predetermined shape with a pressure of 800 to 1000 kg / cm ² . It can be obtained by firing this molded body at a temperature rising rate of 100 ° C./hour and a maximum temperature of 1400 to 1450 ° C. The molding method is not limited to press molding, and may be a cast molding method, a doctor blade method, an extrusion molding method, or the like.

[0010]

EXAMPLE Magnesia powder obtained by calcining magnesium hydroxide at a predetermined temperature and commercially available alumina and stabilized zirconia were adjusted to have a compounding ratio shown in Table 1, and alcohol was used as a solvent in an alumina pot mill. As a small amount, an organic binder, a deflocculant, etc. were added and wet mixed. The obtained slip was dried and granulated with a spray dryer, and the molding pressure was adjusted to 8
A flat plate of 100 × 100 × 6 mm was pressed at 00 kg / cm ² and baked at a predetermined temperature for 4 hours. From the obtained sintered body, bulk specific gravity, bending strength, elastic modulus, and thermal shock strength were evaluated. Bulk specific gravity is measured by Archimedes method, bending strength and elastic modulus are measured by a three-point bending test, and thermal shock strength is 85.
A flat plate of × 85 × 5 mm was immediately put in water from a dryer kept at a predetermined temperature, and the temperature difference in which a crack was generated was expressed by the difference. Since this method is greatly affected by the shape of the sample, it was performed with a size close to the shape actually used. The results obtained are shown in Table 1. In Table 1, No. Nos. 1 to 5 are examples of the present invention. 6 to 9 show comparative examples. Table 1 shows that the addition of zirconia markedly improves the bending strength and the thermal shock strength even when fired at a relatively low temperature.

[0011]

[Table 1]

[0012]

INDUSTRIAL APPLICABILITY As described above, the magnesia porcelain composition of the present invention has the thermal shock strength and bending strength desired as a kiln tool for electronic parts containing lead oxide, and is sufficiently porcelain at low temperature. It can be said that being able to do so is also meaningful from the viewpoint of energy saving.

Claims (1)

[Claims] 1. A magnesia porcelain composition for a kiln tool, characterized in that it comprises MgO; 90 to 98% by weight, Al ₂ O ₃ ; 1 to 10% by weight, ZrO ₂ ; 0.5 to 10% by weight. Magnesia porcelain composition.