JPH07187864A - Firing jig with thermally sprayed layer and its production - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a thermally sprayed layer, to make the layer excellent in durability in spite of a single layer and to obtain a firing jig by a low-cost simple method. CONSTITUTION:An unstabilized zirconia-based thermally sprayed layer not contg. a stabilizing agent is formed on the surface of a magnesian substrate having >=95wt.% magnesia content to produce the objective firing jig.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintering jig, and more particularly to a sintering jig suitable for sintering electronic parts such as ceramic capacitors and thermistors without distortion.

[0002]

2. Description of the Related Art Conventionally, for firing electronic parts such as ceramic capacitors and thermistors, an alumina-based firing jig is used, and a zirconia-based setter is placed on the alumina-based firing jig. The object to be fired, such as a ceramic capacitor, is placed on and fired. In recent years,
A firing jig in which a yttria-stabilized zirconia sprayed layer is formed on the surface of an alumina-based material such as alumina-silica has been developed and used.

[0003]

However, when firing electronic components, the former requires two types of members, an alumina firing jig and a zirconia setter, which not only hinders automation of firing of electronic components. However, there is a problem that the work load is low due to the large load.
Further, there are various problems such as a decrease in thermal efficiency due to heat loss due to the zirconia-based setter and an increase in firing cost.
Further, as a solution to this problem, a firing jig having a yttria-stabilized zirconia sprayed layer formed on the surface of an alumina-based substrate such as the latter has come to be used.
The firing jig having this sprayed layer has the following problems.

(1) When the yttria stabilization rate is increased (complete stabilization), the difference in the coefficient of thermal expansion between the base material and the sprayed layer becomes large, and as the number of times of use increases, the sprayed layer becomes cracked, cracked, peeled, etc. The yttria stabilization rate must be suppressed to some extent, as this will cause (2) On the other hand, if the yttria stabilization rate is suppressed, destabilization of the sprayed layer is likely to proceed gradually, which may cause cracks, cracks, peeling, etc. in the sprayed layer. The range of yttria stabilization is narrow. (3) Further, the specific gravity of the base material is relatively high, and therefore, in order to reduce the weight in order to improve workability, it is necessary to increase the porosity considerably, but to manufacture a base material having a high porosity. Is very difficult.

Therefore, as a result of various studies on the above problems, the present inventor found that when a non-stabilized zirconia sprayed layer was formed by spraying an unstabilized zirconia sprayed layer on a magnesia substrate. It was found that there is almost no difference in the coefficient of thermal expansion between the stabilized zirconia-based sprayed layer and the magnesia-based substrate while incorporating and stabilizing the oxide component in the magnesia-based substrate. Came to make. Therefore, the first object of the present invention is to
It is an object of the present invention to provide a jig for magnesia firing which prevents deterioration of the sprayed layer due to repeated use, has excellent durability with a single sprayed layer, is inexpensive, and is relatively lightweight. A second object of the present invention is to provide a firing jig which prevents deterioration of the sprayed layer due to repeated use, has excellent durability, is inexpensive, is relatively lightweight, and can be manufactured by a simple method. It is to provide a manufacturing method.

[0006]

The above object of the present invention is characterized by having an unstabilized zirconia sprayed layer containing no stabilizer on the surface of a magnesia base material having a magnesia content of 95% by weight or more. It is achieved by a firing jig. The unstabilized zirconia sprayed layer containing no stabilizer is formed by spraying on the surface of the magnesia base material, which is achieved by a method for manufacturing a firing jig.

The present invention will be described in more detail below. The magnesia base material used in the present invention has a magnesia content of 95% by weight or more, preferably 95% by weight to 10% by weight.
It is 0% by weight. The other components are unavoidable components such as silica and calcia. Further, as the unstabilized zirconia-based material containing no stabilizer used in the present invention, those containing 97% by weight to 100% by weight of zirconia and other unavoidable components (silica, calcia, etc.) are preferably used. Such an unstabilized zirconia sprayed layer containing no stabilizer is stabilized by incorporating oxide components such as magnesia and calcia contained in the magnesia base material. As a result, there is almost no difference in the coefficient of thermal expansion between the zirconia sprayed layer incorporating the oxide component and the magnesia base material. The zirconia sprayed layer incorporating the oxide component contains the oxide component in an amount of 0.1% by weight to 25% by weight. Oxide component is 5% to 20% by weight
When the oxide component is less than 5% by weight, the zirconia layer itself is unstable and the durability of the sprayed layer is reduced.
On the other hand, when the amount of calcia exceeds 20% by weight, the amount of oxide contributing to the stabilization of the zirconia layer becomes excessive, and this excessive amount adversely affects the material to be fired, which is not preferable.

In the present invention, in order to form an unstabilized zirconia thermal sprayed layer containing no stabilizer on the surface of the zirconia-based substrate, thermal spraying is carried out according to a conventional method using a commonly known thermal spraying apparatus. be able to. The thermal spraying conditions in this case are as follows: plasma atmosphere temperature 10000 ° C to 15000 ° C.
The outflow velocity at the nozzle is 100 to 500 m / sec,
Further, as the unstabilized zirconia-based member containing no stabilizer which is sprayed on the surface of the zirconia-based base material, the average particle size is 1
Powders of 0 μm to 60 μm, preferably 20 μm to 50 μm can be used. Further, the thickness of the unstabilized zirconia sprayed layer containing no stabilizer is 0.1 mm to 1 mm.
If the thickness of the sprayed layer is less than 0.1 mm, the improvement effect due to the formation of the sprayed layer cannot be obtained. Further, when the thickness of the sprayed layer exceeds 1 mm, the adhesive force is lowered, resulting in problems such as easy peeling and higher cost. Electronic components such as ceramic capacitors and thermistors can be fired using the firing jig of the present invention.

[0009]

In the present invention, the non-stabilized zirconia sprayed layer containing no stabilizer is formed by forming the non-stabilized zirconia sprayed layer containing no stabilizer on the surface of the magnesia substrate. Since the zirconia sprayed layer takes in the oxide component in the base material to form a sprayed layer having a uniform composition, the zirconia sprayed layer gradually stabilizes and finally becomes highly stable. A sprayed zirconia layer appears. Between the zirconia sprayed layer thus obtained and the magnesia base material, the difference in the coefficient of thermal expansion is almost eliminated, and the zirconia sprayed layer obtained in this manner is a magnesia base material. The adhesive force of becomes stronger. As a result, with the firing jig of the present invention, it is possible to obtain a thermal sprayed layer which is not repeatedly cracked, peeled, or the like due to repeated use, and has extremely excellent durability.

[0010]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example Unstabilized zirconia powder (average particle size 20 μm) was formed on the surface of a magnesia base material (250 mm × 250 mm × 8 mm) containing 98% by weight of magnesia and the balance being inevitable components.
And a plasma atmosphere temperature of 150 using a plasma spraying apparatus.
Thermal spraying was performed at 00 ° C. at a nozzle outflow rate of 300 m / sec to form a thermal sprayed layer having a thickness of 0.2 mm, and the firing jig of the present invention was manufactured. The ceramic capacitor was fired using the firing jig having the sprayed layer thus produced. Firing was carried out at 1400 ° C. for 2 hours, and this firing was repeated 50 times. However, peeling of the thermal sprayed layer did not occur, and stable use was possible for a long period of time. The characteristics and quality of the obtained capacitor were also good.
FIG. 1 is a perspective view showing a firing jig of the present invention. 1
Is a magnesia base material, and 2 is an unstabilized zirconia sprayed layer sprayed on its surface.

On the other hand, as a comparative example, the same as the example except that an alumina base material (85% by weight of alumina, 12% by weight of silica, the balance being an unavoidable component) was used instead of the magnesia base material. Then, a firing jig was manufactured.
Using this firing jig, the ceramic capacitor was fired under the same conditions as in the examples. However, when the firing was repeated 1 to 3 times, the sprayed layer partly peeled off and became unusable.

[0013]

According to the method for manufacturing a firing jig of the present invention,
No cracks, cracks, peeling, etc. of the sprayed layer occur at all, and therefore, a jig having extremely excellent durability and a light weight can be easily and easily obtained. Further, the firing jig of the present invention is significantly less expensive than the one having the yttria-stabilized zirconia sprayed layer, and it is possible to manufacture a firing jig having a larger shape, which is industrially possible. It has an extremely remarkable effect of being extremely useful.

[Brief description of drawings]

FIG. 1 is a perspective view showing a firing jig of the present invention.

[Explanation of symbols]

1 Magnesia base material 2 Unstabilized zirconia sprayed layer

Claims (2)

[Claims] 1. A firing jig characterized by having an unstabilized zirconia sprayed layer containing no stabilizer on the surface of a magnesia base material having a magnesia content of 95% by weight or more. 2. A method for producing a firing jig, which comprises spraying an unstabilized zirconia sprayed layer containing no stabilizer on the surface of a magnesia base material having a magnesia content of 95% by weight or more.