JPS6018511B2 - water soluble mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-soluble mold suitable for cast iron, copper alloys, aluminum alloys, and the like.

Conventional casting molds are broadly classified into those using inorganic binders and those using organic binders.

Among these, molds using inorganic binders have good heat resistance, but they often have a large residual strength after heating at high temperatures, so it often takes time to remove the mold. Furthermore, molds using organic viscosifiers tend to disintegrate because the organic matter decomposes at high temperatures, and the molds can be easily removed, but there are problems with heat resistance. The purpose of this invention is to provide a water-soluble mold that has good heat resistance and disintegration properties after casting, and is made of refractory particles such as silica sand, alumina, magnesia, zircon, olivine, and chromite as a base material. It is molded using twill metaphosphate as a binder. This substrate can be used as long as it is opposed to metaphosphates and does not produce permanent compounds.

In addition, it is necessary that the metal ions of metaphosphates do not react with the base material to create insoluble compounds. For example, when silica sand is used as the base material, metaphosphates such as Ca, Al, and Mg are used as binders. For alumina, metaphosphates such as K and Na are suitable. Also, metaphosphate and metaphosphoric acid (HP0
A mixture with 4) can also be used.

Since metaphosphate polymerizes at high temperatures to form polymetaphosphoric acid, it has a strong ability to bind refractory particles.

Although some polymetaphosphates are insoluble in water, trimetaphosphates (for example, M3 (P309); M is a monovalent metal) generally dissolve well in water, and are generally not dissolved in the mold heated to high temperatures during casting. The mold collapses upon water injection due to the formation of trimetaphosphate.

Metaphosphoric acid also exists as a polymer and has a caking effect.
After being cast into a mold containing it, it disintegrates with water.

Metaphosphoric acid is obtained by adding water to phosphorus pentoxide, metaphosphates are obtained by dissolving metal oxides or metal hydroxides in metaphosphoric acid, or by heating calculated amounts of orthophosphoric acid and metal oxides. .

〔Example〕

[1} 3 parts of aluminum metaphosphate and 2 parts of water were added to 100 parts of No. 7 silica sand, molded, and dried at 20,000 ℃.

This molded body had a compressive strength of 40k9/lump or more, and when water was poured into the mold after casting the cast iron, the mold collapsed. [2
' 100 parts of No. 7 silica sand, 4 parts of calcium metaphosphate, 2 parts of water
．． 5 parts were added, molded and dried at 20030.

This molded body had a compressive strength of 30k9/m or more, and when water was poured into the mold after casting the aluminum alloy, the mold easily collapsed. '31 Alumina (120 mesh) 1
0 parts of sodium metaphosphate and 4 parts of water were added, molded, and dried at 200°C.

This molded body had a compressive strength of 50k9/y or more and could be used for casting cast iron, steel alloys, and aluminum alloys, and a mold that easily disintegrated with water after casting was obtained. As explained above, the present invention is a water-soluble mold that uses a refractory as a base material and uses a metaphosphate or a mixture of metaphosphoric acid and metaphosphate as a binder.

Claims (1)

[Scope of Claims] 1. Refractory particles such as silica sand, alumina, magnesia, zircon, chromite, and olivine are used as a base material, and a water-soluble metaphosphate or a mixture of metaphosphoric acid and metaphosphate is used as a binder. A water-soluble mold characterized by molding. 2. Claim 1, wherein the metaphosphate is a phosphate of Ca, Al, Mg, K, or Na.
Water-soluble mold as described in section.