JPH07115942B2 - Method for manufacturing thin plate ceramics sintered body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a thin plate ceramics sintered body,
More specifically, the present invention relates to a method for manufacturing a thin plate ceramics sintered body, which is obtained by performing hot press molding at low pressure to obtain a thin plate-shaped ceramics sintered body having a theoretical density of 95% or more and a thickness of 1 to 5 mm.

[Prior Art] When a thin plate-shaped ceramics sintered body is manufactured, a die molding method, a rubber pressing method, a slip casting method, a doctor blade method and the like have been conventionally used for forming a raw material powder. In the case of manufacturing a thin plate-shaped ceramics sintered body having a high density of 95% or more in theoretical density and a thickness of 1 to 5 mm by these methods, there are the following problems.

In the molding method, it is necessary to set the molding pressure to 300 kg / cm ² or more. For this reason, a large-sized press device is required to form the above-mentioned thin plate shaped body.

In the rubber press method, since the molded product is a thin plate having a thickness of 1 to 5 mm, the molded product is liable to warp, and a good molded product cannot be obtained.

By the slip casting method, it is possible to obtain a thin plate-shaped molded body having a thickness of 5 mm or less. However, it is difficult to manufacture such a thin plate-shaped molded product with a high density of 95% or more of the theoretical density.

According to the doctor blade method, a molded product having a thickness of 1 mm or less can be molded, but it is difficult to manufacture a thin plate-shaped molded product having a thickness of more than 1 mm.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to achieve a theoretical density of 95% or more at a sufficiently low molding pressure without using a large press machine.
It is an object of the present invention to provide a method for manufacturing a thin plate ceramics sintered body capable of favorably manufacturing a large-sized thin plate ceramics sintered body having a thickness of 1 to 5 mm.

[Means for Solving Problems] A method for manufacturing a thin plate ceramics sintered body of the present invention is a method for manufacturing a thin plate ceramics sintered body having a theoretical density of 95% or more and a thickness of 1 to 5 mm, comprising the steps (a): A step of wet-mixing the ceramic powder with a heat-softening organic binder in an amount of 3 to 10 parts by weight to obtain a raw material powder; and (b) a step of producing a granulated powder using the raw material powder. (C) filling the granulated powder into a rigid molding die, and (d) setting the molding temperature to a temperature at which the organic binder softens, and molding pressure of 80 to 200 kg /
a step of hot pressing the granulated powder in the molding die with a setting of cm ² to obtain a thin plate-shaped molded body; and (e) heating the molded body at a sintering temperature higher than the molding temperature. Then, the steps of removing the organic binder and sintering the molded body are included.

As the ceramic powder, any powder can be used depending on the type of sintered body to be manufactured. Examples thereof include aluminum oxide powder and zirconium oxide powder. This ceramic powder may contain a sintering aid, a partial stabilizer, and the like in addition to the organic binder.

As the heat-softening organic binder, synthetic resin binders such as polyethylene-based binders, polyurethane-based binders, and acrylic-based binders can be preferably used.

The amount of the organic binder is set to 3 to 10 parts by weight, because if the amount of addition is less than 3 parts by weight, the density of the molded body does not increase and good molding is impossible, and if the amount of addition exceeds 10 parts by weight, This is because the properties of the sintered body (particularly bending strength) are reduced.

The reason why the ceramic powder and the organic binder are wet-mixed is to ensure good mixing thereof.

The rigid forming die is used in the forming step, because the sintered body to be obtained is a thin plate having a thickness of 1 to 5 mm, and if the rigid forming die is not used, defects such as warpage will occur during forming. Is.

The molding temperature is set to a temperature at which the organic binder is softened, by softening the organic binder, the organic binder easily fits into the ceramic powder during molding,
As a result, sufficient molding strength can be obtained even when the molding pressure is as low as 80 to 200 kg / cm ² .

The molding pressure is set to 80 to 200 kg / cm ² is 80 kg / cm.
^This is because if it is less than ² , a sufficient compact density cannot be obtained and cracks are likely to occur in the compact, and if it exceeds 200 kg / cm ² , a large press machine is required. Also, the molding pressure
This is also because the density of the molded body reaches a saturated state at about 200 kg / cm ² , and there is almost no effect even if the molding pressure is further increased.

The sintering temperature may be higher than the molding temperature, and can be set to any temperature depending on the type of ceramic powder used.

In the present invention, a mold is used as the rigid molding die,
It is possible to manufacture a large-sized thin plate ceramics sintered body, but it is also possible to form a complex shape having a thickness of 1 to 5 mm or less.

Further, since 5 to 10 parts by weight of the organic binder is added to the raw material powder, there are advantages such as high strength of the molded body, easy processing of the molded body, and less processing of the sintered body.

[Operation] In the present invention, when the raw material powder is obtained, the addition amount of the thermosoftening organic binder to be mixed with the ceramic powder is limited to 3 to 10 parts by weight. Therefore, good formability and sintered body strength can be obtained at the same time.

In addition, while the molding temperature is set to a temperature at which the organic binder softens (for example, 140 ° C.) to soften the organic binder in the molded body, the molding pressure is set to a low pressure of 80 to 200 kg / cm ² to granulate. The powder is hot pressed. Therefore, the thickness is 1 to 5 mm without using a large press machine.
It is possible to obtain a thin plate-shaped molded article of good quality.

Also, since the granulated powder is filled into the rigid mold during molding,
There is no fear that the molded article will be warped as in the rubber press method.

Therefore, if the molded body thus obtained is sintered at a sintering temperature higher than the molding temperature, a thin plate-shaped molded body having a theoretical density of 95% or more and a thickness of 1 to 5 mm can be satisfactorily obtained.

[Examples] Examples of the present invention will be described below.

(Example 1) A zirconium oxide powder having an average particle size of 0.3 µm or less containing 3.0 mol% of yttrium oxide as a partial stabilizer was uniformly wet-mixed with an organic binder to prepare granulated powder.

Next, this granulated powder is filled into a mold having a 200 mm square thin plate-shaped molding space, and hot pressing is performed by pressing for 30 minutes at a temperature at which the organic binder softens. A shaped body was obtained.

As the organic binder, three types of organic binders of polyethylene type, polyurethane type and acrylic type were used. The amount of the organic binder added was 5 parts by weight in each case.

The relationship between the press temperature (molding temperature) and the density of the molded body was determined while maintaining the press pressure (molding pressure) at 100 kg / cm ² , and the result is as shown in FIG. As can be seen from FIG. 1, for each organic binder, a high compact density was obtained at a specific temperature at which it softens. Especially when using a polyethylene binder, press at a temperature of 140 ° C.
A high compact density of 4.0 g / cm ³ was obtained. Pressing temperature is around 160 ℃ for polyurethane organic binder and 150 ℃ for acrylic organic binder.
In the vicinity, a respectively high green compact density was obtained.

Next, while maintaining the pressing pressure (molding pressure) at 100 kg / cm ² , the addition amount of the polyethylene-based binder to the zirconium oxide powder was changed to examine the relationship between the pressing temperature and the density of the molded body. The results are shown in FIG.

As can be seen from FIG. 2, when the amount of the polyethylene-based binder added is increased, the density of the molded body (that is, the strength of the molded body) is improved, and the molding can be performed in a wide temperature range. However, when the addition amount of the polyethylene-based binder is less than 3 parts by weight, a sufficient molded body density cannot be obtained, and as a result,
The molded body was cracked and could not be molded satisfactorily.

Next, 5 parts by weight of a polyethylene-based binder was added to the zirconium oxide powder, and hot press molding was performed at a pressing temperature of 140 ° C. for 30 minutes. The relationship between the press pressure and the compact density obtained as a result is shown in FIG. From FIG. 3, when the pressing pressure was less than 80 kg / cm ² , the density of the molded body (molded body strength) was not sufficient, and cracks occurred in the molded body.

When the pressing pressure exceeded 200 kg / cm ² , the density of the compact reached a saturated state, and there was no effect even if the pressing pressure was increased further.

Then, these compacts were heated at an appropriate sintering temperature higher than the pressing temperature to remove (degrease) the organic binder in these zirconium oxide compacts and sinter. The characteristics of the sintered body thus obtained are shown in Table 1.

In Table 1, K _IC-VI shows fracture toughness by Vickers method.

It can be seen from Table 1 that when the amount of the organic binder added exceeds about 5 parts by weight, the properties of the sintered body tend to be slightly deteriorated.

Regarding the pressing pressure, as can be seen from Experiment Nos. 6 to 11, when the pressing pressure is 80 kg / cm ² or more, the characteristics of the obtained sintered body are almost constant.

(Example 2) 0.25 wt% of magnesium oxide is contained as a sintering aid,
A polyethylene-based binder was uniformly wet-mixed with aluminum oxide powder having an average particle size of 5 μm or less to prepare granulated powder.

In the same manner as in Example 1, this granulated powder was filled in a mold of 200 mm square, and at the temperature at which the polyethylene binder softened.
Hot press molding was carried out for 30 minutes to obtain a thin plate-like molded body having a thickness of 2.0 mm and a size of 200 mm square.

Next, a polyethylene binder was added to the aluminum oxide powder, and the relationship between the press temperature and the density of the molded body was investigated. As a result, as in the case of Example 1, the density of the molded body (molded body strength) was improved when the amount of the binder added was increased, and molding was possible in a wide temperature range. However, when the amount of the binder added was less than 3 parts by weight, the density of the molded body did not increase, and cracking occurred, making molding impossible.

In FIG. 5, 5 parts by weight of a polyethylene-based binder was added to aluminum oxide powder, and the pressing temperature was 140 ° C. for 30 minutes.
The relationship between the press pressure and the compact density when hot press molding is performed is shown. When the molding pressure was 80 kg / cm ² or less, the density of the molded body did not increase and the molded body did not have sufficient strength, so cracking occurred. Further, when the molding pressure was 200 kg / cm ² or more, the density of the molded body reached a saturated state, and even if the molding pressure was further increased, the density of the molded body did not rise.

Then, these aluminum oxide compacts were degreased and sintered. Table 2 shows the characteristics of the sintered body. In Table 2, K _IC-VI shows fracture toughness by Vickers method.

From Table 2, as in Example 1, when the addition amount of the organic binder is more than about 5 parts by weight, the properties of the sintered body tend to be slightly deteriorated, and the pressing pressure is 80 kg / cm ² or more. It can be seen that the characteristics of the sintered body are almost constant.

[Effects of the Invention] In the method for producing a thin plate ceramics sintered body of the present invention, a large thin plate ceramic having a theoretical density of 95% or more and a thickness of 1 to 5 mm is used at a sufficiently low molding pressure without using a large press machine. A sintered body can be manufactured well.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the compact density and the pressing temperature when raw material powders obtained by adding three kinds of organic binders to zirconium oxide are used. FIG. 2 is a graph showing the relationship between the compact density and the pressing temperature with the amount of polyethylene organic binder added as a parameter, when raw material powder obtained by adding polyethylene organic binder to zirconium oxide is used. FIG. 3 is a graph showing the relationship between the compact density and the press pressure when 5 parts by weight of a polyethylene organic binder is added to zirconium oxide. FIG. 4 is a graph showing the relationship between the compact density and the press temperature with the addition amount of the polyethylene organic binder as a parameter when the polyethylene organic binder is added to aluminum oxide. FIG. 5 is a graph showing the relationship between the compact density and the press pressure when 5 parts by weight of a polyethylene-based organic binder is added to aluminum oxide.

Claims (1)

[Claims] 1. A method for producing a thin plate ceramics sintered body having a theoretical density of 95% or more and a thickness of 1 to 5 mm, comprising: (a) 3 to 10 parts by weight of a thermosoftening organic binder in a ceramic powder. A step of wet mixing to obtain a raw material powder, (b) a step of producing a granulated powder using the raw material powder, and (c) a step of filling the rigid formed mold with the granulated powder. d) The molding temperature is set to a temperature at which the organic binder is softened, the molding pressure is set to 80 to 200 kg / cm ² , and the granulated powder in the molding die is hot-press molded to obtain a thin plate-shaped molded body. And (e) heating the molded body at a sintering temperature higher than the molding temperature to remove the organic binder and sinter the molded body. Manufacturing method of sintered body.