JPS5920368B2 - Manufacturing method of “filtration” body for metal casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a filter body when casting metal.

Conventionally, when casting metals, especially light metals and non-ferrous metals,
In order to remove oxide films and foreign substances from the molten metal and to ensure an even flow of the molten metal, high-melting point metal nets are installed at sprues, runners, etc.
Alternatively, a filter material such as a glass fiber mesh coated with an organic resin and then carbonized at high temperature is used.

The properties required for these filters are that when used under various conditions, the desired coarseness of the filter can be freely selected in order to achieve smooth filtration and vortex flow. It is easy to attach and detach, is stable at high temperatures, and does not break down during use, which would cause debris to enter the casting.

Furthermore, the filter body must not adhere to the molten metal in order to maintain a smooth flow of hot water, and must have low thermal conductivity to prevent heat dissipation and prevent the temperature of the molten metal from dropping. is desirable.

The most important thing is that the filter itself does not decompose with hot water and generate volatile gases, or react with molten metal and introduce impurities into the casting.

When looking at the conventional Okinawa body from this point of view, the high melting point metal mesh has high thermal conductivity and is likely to cause a drop in temperature, and the high wettability with molten metal creates a large resistance to the flow of hot water. In some cases, a small amount of wire mesh may be melted into the hot water.
It has drawbacks such as the possibility of affecting the composition of the molten metal and the metal being difficult to peel off when the wire mesh is removed.

On the other hand, fiber nets made of alkali-free glass, silica glass, etc. coated with organic resins and then carbonized have advantages as filters, such as ease of processing and good removability of molten metal. However, it is not necessarily the optimal one.

In other words, if you carbonize by baking at high temperature after coating with organic resin, if you do not completely carbonize it, organic gas will be generated when you pour hot water, and conversely, if you do not completely carbonize it. It is difficult to obtain satisfactory results using this method, as the material becomes brittle and brittle, and problems often occur.

Furthermore, depending on the metal to be cast, there are cases where even the slightest amount of carbon is extremely objectionable, and a filter body made by this method cannot be used for this purpose at all.

In view of the above, the present invention aims to provide a method for manufacturing a filter that does not contain any organic carbon, has excellent quality stability, and has good filtration efficiency. The method involves coating a base material made of heat-resistant fibers with a composition containing silicone resin and ceramic fine powder as main components, and then hardening and firing the composition.

Various types of fibers can be used as the heat-resistant fibers, such as glass fibers such as alkali glass, non-alkali glass, and silica glass, ceramic fibers such as silica, alumina silicate, and potassium titanate, and carbon fibers.

It is desirable that the fibers be heat resistant and at the same time have low thermal conductivity, and in this sense, inorganic fibers are better than metal fibers.

The base material has a mesh shape, but its form is not particularly limited. For example, it may be mat-like, felt-like or other non-woven materials, or knitted or woven into regular mesh shapes. The term "mesh-like" includes all of these forms used for filtering molten metal.

The coarseness of the mesh can be arbitrarily selected depending on the purpose of the p-filtration and the properties of the molten metal.

The composition to be coated on the surface of these heat-resistant fiber substrates contains silicone resin and ceramic fine powder as main components, with low melting point glass frit and ordinary coating agent added as necessary.

The composition is usually used as a paint by adding a solvent to it.

Silicone resins include not only straight silicone resins but also modified silicone resins such as epoxy-modified and urethane-modified silicone resins, and these are used in solutions, emulsions, suspensions, and the like.

Ceramic fine powders include natural or synthetic mica, silica, talc, ZrO2, TiO2, ZnO, 2Ca()S i
02, S t 3N4, S r C, etc., and other materials can be used as long as they are heat resistant and do not react with the molten metal.

These fine powders are preferably about 325 mesh or less.

The coating agent used in the present invention is mainly composed of the above-mentioned silicone resin and ceramic fine powder, but in order to improve the strength of the coating film in the low to medium temperature range, phosphate frit, borosilicate frit, boric acid frit, and titanium frit are used. Low melting point glass frits such as dispersants, emulsifiers, chicken fillers, leveling agents, anti-settling agents, antifoaming agents and other so-called coating agents commonly used in coatings are added as necessary.

A good blending ratio of the coating composition is silicone resin 10 to 80 parts (by weight, the same applies hereinafter), preferably 15 to 80 parts.
60%, fine ceramic powder has a ratio of 10 to 70, preferably 15 to 60, and low melting point glass frit usually has a ratio of 0 to 4.
The coating agent is added in an amount of 0 to 10.

The composition formulated as described above is sufficiently mixed and dispersed using a dispersing machine such as a ball mill, sand mill, shaker, or roll mill, and then a solvent is added thereto to form a coating material.

The solvent used is an organic solvent that dissolves the silicone resin, or water that does not dissolve the silicone resin, and emulsion type, suspension type, etc. paints are produced.

This paint is coated on the surface of the heat-resistant fiber base material having the above-mentioned mesh shape.

Coating methods include roll coating, dipping machine, spray coating, brush coating, etc., and are not particularly limited.

After coating, the film is cured and fired.

Curing is suitably carried out at 150-250°C for 30-90 minutes.

After curing, it is cut into a shape according to the purpose of use, but it can also be press-molded using a mold in advance to form an uneven shape and then hardened.

Next, these are baked at 400 to 600°C for 0.5 to 5 hours to obtain the desired filter body.

In the present invention, the silicone resin functions as a coating film-forming element, and during firing, a 10-8i-0-compound is produced without leaving any carbon components, which acts as a heat-resistant inorganic binder to strengthen the ceramic fine powder (: This is combined.

As a result, the film does not peel off easily.

Ceramic fine powder not only provides heat resistance to the film, but also
It acts as a filler and prevents cracks in the film.

Furthermore, if a crack occurs on the surface, it prevents the crack from progressing inside.

As a result, molten metal is prevented from penetrating into the coating.

Since the structure of the present invention having such properties does not contain any organic carbon, no gas is generated during casting (therefore, no cavities are formed in the cast product).

In addition, since the molten metal and the liquid do not react with each other, it does not affect the molten metal components, and since the peeling property against the molten metal is good, the resistance to filtration is small.

Furthermore, since the heat conductivity of the sewage body is low, it does not cause a drop in the temperature of the molten metal, and since the film of the filter body does not peel off easily, there is no possibility that foreign matter will be mixed into the casting.

The filter body of the present invention has many advantages such as relatively free selection of mesh coarseness and simple manufacturing process.

Next, the present invention will be explained with reference to Examples.

Example (1) Preparation of paint) Silicone resin KR-22019 manufactured by Shin-Etsu Chemical @)
2 parts by weight, the same hereinafter, silicone resin varnish KR-282
(manufactured by the same company) 96 parts, 48 parts of fine powder talc under 325 mesh each, 43 parts of titanium oxide, 148.8 parts of fused silica
272 parts of perchlorethylene and 200 parts of 1.1.1° trichloroethane were added and dispersed in a shaker for 30 minutes to obtain a paint with a concentration of 48.

(0) Silicone resin manufactured by Shin-Etsu Chemical (A) (K, R-
275) Mica 8 under 325 mesh in 505.2 parts each
3.2 parts, 43.2 parts of fused silica powder, and 126.3 parts of phosphate frit (#4021 made by Nippon Enamel) were added, and BYK- was added as a dispersant.
5 parts of P104S, and 237% of Park's ethylene.
1 part was added and dispersed three times using three rolls to obtain a paint with a concentration of 50.

(/9 Shin-Etsu Chemical Co., Ltd. silicone resin (KR-
220) powder, 73.2 parts of finely powdered talc under 325 mesh, 65.9 parts of titanium oxide, 73.2 parts of fused silica powder, and 153 parts of borosilicate frit (Japanese Enamel #4320). .8 parts, 30 parts of a 20% casein solution dissolved in aqueous ammonia as a stabilizer, and 5 parts of sodium ligninsulfonate as a dispersant were added together with 442 parts of water.
The mixture was dispersed in a ball mill for 24 hours to obtain a water-based paint with a concentration of 52%.

12) Preparation and casting test of filter body The paints obtained in the above (/r), (b), (/h) are placed on a non-alkali glass fiber mesh and a carbon fiber mat, and in the case of the former, 10% of the weight of each In the latter case, the silicone resin was cured for 1 hour at 200°C, then cut, and then at 500°C for 30°.
A filter body coated with a hard film was obtained by baking for a minute.

When this was attached to the sprue of an aluminum casting machine and casting was carried out, the casting work could be carried out extremely smoothly.

During this period, no gas generation or foreign matter was observed.

Furthermore, it was extremely easy to peel off the cast material after work, resulting in less material loss and shorter work time.

Claims (1)

[Claims] 1 Coating a composition mainly composed of silicone resin and ceramic fine powder on the surface of a heat-resistant fiber base material configured in a mesh shape, and after curing, baking to remove carbon in the silicone resin, A method for producing a filter body for metal casting, characterized in that it is a compound with a -0-8i-0- bond.