JPH05200480A - Production of ceramic core - Google Patents

Abstract

PURPOSE:To enable molding and calcining of the core having an excellent collapsing property by kneading a silica sol with a compounded material formed by compounding zircon powder with zircon sand, etc., and ramming the mixture. CONSTITUTION:The silica sol is kneaded with the compounded material formed by compounding the zircon powder with the zircon sand, etc., or the particles of the molten silica and the mixture is rammed and molded to the core. The core is then calcined. The molding having suitable strength is obtd. by bonding coarse grained ceramic refractories with fine grained ceramic refractories and silica sol. The molding does not crack at the time of drying and calcining to the core and the core is stably produced. In addition, the core having the excellent collapsing property is obtd. The operation to remove the core of the casting is facilitated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method of manufacturing a ceramic core for casting.

[0002]

2. Description of the Related Art As a conventional method for producing a ceramic core, most of them are kneaded with a ceramic refractory and a binder, as represented by show process, unicast, etc.
A method of pouring in a thriller state is known. For example, in the show process, a binder and a hardening agent are added to a ceramic refractory to make a slurry, which is poured into a model,
After curing, heat to make hair clarks on the surface, then 8
Baking for 7 hours at 00 ° C.

[0003]

However, the above-mentioned slurry injection method has the following problems. (1) Since a large amount of binder is used, cracking easily occurs during solidification. (2) Bubbles are easily entrained in the slurry and are easily deposited on the surface. (3) Since it is a dense molded body during firing, it is easily cracked and a large core cannot be formed. (4) Since there are few gaps between the ceramic refractories, disintegration after pouring is extremely poor. (5) It is expensive because a large amount of binder is used.

The present invention has been developed to solve the above problems, and an object thereof is to produce a ceramic core having excellent disintegration property.

[0005]

The constitution of the present invention for attaining the above object is to knead silica sol with a compounding material formed by compounding zircon powder with particles of zircon sand or fused silica. It is characterized by hardening, molding into a core, and baking.

[0006]

According to the present invention, a molded product having an appropriate strength can be obtained by combining the coarse-grained ceramic refractory with the fine-grained ceramic refractory by the above-mentioned means with silica sol. At this time, the strength of the molded body changes depending on the amount of silica sol added and the amount of fine-grained ceramic refractory added.

[0007]

EXAMPLES Examples of the present invention will be shown below. Example 1 Zircon powder having an average particle diameter of 150 μm is mixed with zircon powder having an average particle diameter of 10 μm, and silica sol is added and kneaded. 50 mm × ^H 50 with a refractory material that is kneaded
30mm sand type standard test piece is manufactured, left for 24 hours, then 30
After drying at 0 ° C, 800 ° C ・ 900 ° C ・ 1000 ° C
The test piece after firing was measured at room temperature compressive strength.

First, the amount of the binder added to the raw materials was investigated within a range where the tamping method was possible. It was found that the rust-type strength is improved by increasing the addition amount of the binder, but the addition of 7 to 13 parts by weight of the binder is sufficient to obtain the room temperature strength that can be handled. Next, the strength between the raw materials was investigated.

0 to 5 zircon powder having an average particle size of 10 μm is added to 100 parts by weight of zircon sand having an average particle size of 150 μm.
When 0 part by weight is added, the room temperature compressive strength after firing is improved as shown in FIG. 1 as the amount of zircon powder added increases. In order to obtain the target cold compressive strength, it is desirable to add the zircon powder in an amount of 5 to 30 parts by weight. Based on the above, 100 parts by weight of zircon sand, 25 parts by weight of zircon powder, and 12 parts by weight of silica sol were kneaded to obtain Φ50 mm × ^H 50
mm test piece is molded and dried at 300 ° C → 100
By firing at 0 ° C., a residual compressive strength of 80 kg / cm ² could be obtained as shown in FIG. The disintegration property is represented to some extent by the residual compressive strength, and it can be said that the strength of 80 kg / cm ² is quite good.

Example 2 Zircon powder having an average particle size of 10 μm is kneaded with fused silica having an average particle size of 22 μm, and silica sol is added and kneaded. Other test conditions were the same as in Example 1. As a result, the amount of binder added is 100
12-18 parts by weight are compatible with parts by weight.

Further, it was found that 25 to 70 parts by weight of zircon powder is suitable for 100 parts by weight of fused silica. Based on the above, 100 parts by weight of fused silica, 65 parts by weight of zircon powder and 26 parts by weight of silica sol were kneaded and tested in the same manner as in Example 1 to obtain a residual compressive strength of 67 kg / cm ² . It can be said that the disintegration is better than that of Example 1.

[0012]

As described above, according to the present invention, a silica sol is kneaded with a compounding material formed by mixing zircon sand or particles of fused silica with zircon powder, solidified, molded into a core, and fired. As compared with the conventional slurry pouring method, even a large core can be stably manufactured without cracking during firing and a core excellent in disintegration can be obtained as compared with the conventional slurry pouring method. This has the effect of facilitating core removal work.

[Brief description of drawings]

FIG. 1 is a relationship diagram of mold strength and zircon powder blending ratio according to a first embodiment of the present invention.

FIG. 2 is a change diagram of the mold strength according to the first and second embodiments of the present invention.

Claims (1)

[Claims] 1. A ceramic material characterized by kneading and solidifying silcasol to a compounding material formed by compounding zircon sand or fused silica particles with zircon powder, molding into a core and firing. Child manufacturing method.