JPS5846471B2 - Manufacturing method of ceramic products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in methods for manufacturing ceramic products.

Conventional ceramic molding methods include slip casting, in which ceramic slurry is poured into a plaster mold, and plastic inorganic minerals such as clay, or organic substances such as polyvinyl alcohol and starch are added to ceramic powder to make the ceramic plastic. There is a method of press molding or extrusion molding after giving the material a .

Furthermore, rubber press molding is also suitable for molding cylindrical ceramics.

In recent years, injection molding, transfer molding, and press molding, which are already widely used in plastic molding, have begun to be considered as methods for mass-producing high-precision ceramic parts.

These molding methods add plasticity to ceramic powder by adding and kneading organic materials such as plastic, and then injection molding or transfer molding is performed in the same manner as is normally done for plastics. The injection molded product is heated to decompose and remove the plastic (this process is generally called the degreasing process).

) and then fired or sintered at high temperatures to produce ceramic products.

Most ceramic products can be manufactured using these molding methods, however, when manufacturing ceramic products with extremely large pores, or when using ceramic powder with uniform particle size and poor moldability, these methods may not work. It's inappropriate.

This is because if the plastic is completely removed in the degreasing process, the molded product will be made of ceramic and will not be able to hold its shape and will collapse, making it impossible to mold it.

As a result of various studies, the inventors of the present invention have discovered a method by which even the above-mentioned ceramic having poor formability can be injection molded and sintered without collapsing, and the present invention is provided here.

That is, the method for manufacturing a ceramic product according to the present invention includes:
Ceramic powder is molded by adding an organic binder mainly composed of plastic, and the resulting molded product is degreased so that some of the plastic remains, impregnated with an inorganic binder, and then fired or sintered. It is characterized by:

To explain in more detail, plastic is added to ceramic powder, kneaded, and then molded using normal means.The resulting molded product is then heated and degreased, but at this time some plastic remains. In this method, the molded product is taken out of the degreasing furnace in the same state as the molded product, and then the molded product is impregnated with an inorganic binder and fired.

The amount of plastic remaining during degreasing is 0.0% of the initial molded product.
It is better to add 1 to 5 more weight, but if you want to increase the strength of the ceramic product after firing, it is preferable to use as little as possible.

If a molded product impregnated with an inorganic binder is fired or sintered with some plastic left in the molded product without being completely removed, even if the plastic is completely removed during firing, the impregnated inorganic binder will remain. prevents the molded body from collapsing, and therefore a good ceramic product can be obtained.

Examples of inorganic binders include colloidal silica liquid,
Water glass liquid, lithium silicate, alumina sol, etc. are used.

Using the method according to the invention, even ceramic products with a fairly high porosity and ceramic powders with poor formability can be made into sintered bodies.

Examples are shown below to explain the present invention in more detail, but the present invention is not limited to these Examples.

Further, the amount of residual plastic in each example is calculated as follows.

Example 1 15 weight dumplings (hereinafter referred to as weight-type dumplings) of a resin having the composition shown in Table 1 are added to alumina powder with a particle size of 500 μm to 2000 μm, and the mixture is kneaded in a high-temperature kneader at 180° C. for 60 minutes. .

After kneading, the mixture was formed into a plate with a high temperature roll at 150° C. to produce pellets with a thickness of 5 mm and 2 to 10 mm.

A molded article was obtained from this pellet under injection molding conditions shown in Table 2 below.

Thereafter, degreasing was carried out using a temperature pattern as shown in FIG. 1 to obtain a degreased product in which approximately 1.5% of the plastic remained.

This degreased product was immersed in a colloidal silica solution as shown in Table 3, and dried at 150°C for 1 hour.
A product was obtained by firing in the air at ℃ for 3 hours.

The shape of the product manufactured here (dimension D = 40 mm,
d = 15mm, t = 2mm, L = 50mm)
is shown in Figure 2.

The resulting product had a porosity of 43.

Reference Example l The injection molded product obtained in Example 1 was heated to a degreasing temperature of 4
When the temperature was raised to 00°C to completely remove the plastic, the molded product collapsed.

Example 2 16% of the plastic having the composition shown in Table 1 above was added to mullite powder with a particle size of 1 am or less, and after molding under the same conditions as Example 1, approximately 1.1 of the plastic remained. Degreased to condition.

Thereafter, it was immersed in a JIS No. 3 water glass solution shown in Table 4 below to be impregnated, and dried at 120° C. for 1 hour.

Then, when it was fired in the atmosphere at 1200° C. for 1 hour, a mullite sintered body with a porosity of 51 was obtained.

The shape of the product is the same as shown in FIG.

Reference Example 2 When completely degreased under the same conditions as in Example 2, it collapsed as in Reference Example 1.

Reference Example 3 Under the same conditions as in Example 2, a molded article was placed in the shape shown in FIG. 2 and completely degreased, but it also collapsed.

Reference Example 4 In Example 1, degreasing was stopped leaving about 0.7% of the plastic, and when the plastic was placed in the shape shown in Figure 2 and fired at 1750°C for 3 hours, it still collapsed. have done.

Example 3 15% of the plastic shown in Table 1 above was added to β-spodumene glass beads (Li20-A1202-JS 102) with a particle size of 1000μ to 500μ, and after injection molding, the same procedure as in Example 1 was carried out. The material was heated according to the temperature pattern shown in FIG. 1 and fired so that the amount of residual plastic was about 0.8 yen.

This degreased surface was immersed in colloidal lithium silicate shown in Table 5 to impregnate it, and fired in the air at 1050° C. for 1 hour to produce a ceramic sintered body.

The porosity of the product was 45%.

Moreover, the bending strength was 35 Kycm2.

However, the test piece for transverse cold measurement is 15 meters wide and 50 meters long.
It was manufactured under the same conditions as the above manufacturing method, with a thickness of m1 and a thickness of 10.

Reference Example 5 In Example 3, degreasing was stopped leaving about 0.5% of the plastic remaining, and the plastic was placed as shown in Fig. 2 and placed in a firing furnace, and fired at 1050°C for 1 hour, and found that it had disintegrated.

Example 4 β-spodumene with a particle size of 1000 μm to 500 μm was prepared by adding 15 ml of phenol resin to lath beads and growing at 180°C for 2 hours.
Minute hot press bottom type (pressure 200Kv/cfIL"
) L,, a molded body as shown in Fig. 2 (dimension D = 50 m
m, d==10mm, t=4mm, L=50m
m) was produced.

When the molded body was heated in air from room temperature to 550° C. over 5 hours and taken out, the amount of residual plastic was 13 tons.

Next, this degreased surface was impregnated by immersing it in colloidal lithium silicate shown in Table 5, and calcined in the air at 1050° C. for 1 hour.

The porosity of this product was 46, and there was no deformation or collapse.

Reference Example 6 In Example 4, the degreasing was stopped leaving about 1.3% of the plastic, and the plastic was placed as shown in Figure 2 and placed in a firing furnace.
When fired at 050°C for 1 hour, it was found to have collapsed.

As is clear from the results of the above examples, by using the manufacturing method of the present invention, it is possible to manufacture ceramic products with high porosity, which was thought to be impossible with conventional manufacturing methods.
Moreover, even if the temperature during firing is low, a predetermined strength can be obtained due to the effect of the impregnated binder.

In addition, impregnation with a binder is particularly effective for materials whose crystal phase (or glass phase) undergoes a transition when the firing temperature is high (e.g., stabilized zirconia, fused silica, etc.) and where a certain level of strength is required. .

The fired ceramic products obtained by the manufacturing method of the present invention have excellent strength even in shapes with high porosity, and therefore can be used for precision casting and various ceramic products such as pipes, crucibles, plates, etc. can.

[Brief explanation of drawings]

FIG. 1 is a graph showing the temperature pattern in the degreasing process, and FIG. 2 is a perspective view of a prototype used for molding of the present invention.

Claims (1)

[Claims] 1 Add an organic binder mainly composed of plastic to ceramic powder and mold it, and heat the resulting molded product so that 0.1 to 5 weight of plastic remains based on the weight of the molded product. A method for producing a ceramic product, which comprises degreasing the product, impregnating it with an inorganic binder, and then firing it.