JPH0683886B2 - Mold for casting with coating containing polytitanocarbosilane fiber material and method of making same - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a casting mold having excellent thermal shock resistance, mold releasability, durability and wear resistance, and a method for producing the same.

[Prior Art] Conventionally, a casting die is used while being coated with a commercially available soft coating agent (ceramic kneaded into water glass) every 200 to 300 shots. However, in the case of a copper alloy casting mold, the final shot number is limited to several thousand shots. This is because cracks or wear occur on the surface of the mold body. Therefore, there is a problem in complexity and durability of the coating type.

In recent years, adhesives mainly composed of inorganic components have been studied.
For example, Japanese Examined Patent Publication (Kokoku) No. 50-33491 discloses a mixture of finely divided high-purity zirconium oxide, colloidal silicic acid, and sodium aluminate in an amount of 2 to 10% of their total weight.
Disclosed is a method for producing a high heat-resistant adhesive composition, which is obtained by firing at 00 ° C. or higher and finely pulverizing. The adhesive produced by this method has a low curing temperature,
A curing time of 1 hour at 250-350 ° C is reported to be sufficient.

Furthermore, "Chemistry and Industry", Vol. 39, No. 1, (1986) No. 13
Pages 8 to 140 disclose polytitanocarbosilane fibers that withstand temperatures of 1200 ° C. in air.

However, hitherto, no technique has been developed in which the above-mentioned high heat-resistant inorganic adhesive is combined with this polytitanocarbosilane fiber and applied to a casting mold.

[Problems to be Solved by the Invention] The present invention has been earnestly studied to utilize the above-mentioned adhesive and polytitanocarbosilane fiber in a casting mold, and compared with a conventional casting mold. Remarkably excellent wear resistance,
The challenge is to develop a mold for casting that has releasability and thermal shock resistance.

[Structure of the Invention] Accordingly, the present inventor has found that the polytitanocarbosilane fiber material is attached to the inner surface of the mold by an inorganic adhesive, and the inorganic adhesive contains 35 to 70% by weight of zirconium oxide. , 25 to 60% by weight of silica and the remaining amount of sodium aluminate, and the total thickness of the fiber material and the adhesive coating film is 0.5 to 15 mm, polytitanocarbosilane. It has been found that a casting mold with a fibrous material-containing coating can solve the above problems.

Further, the present inventor has made the following steps in producing the above casting mold having a coating containing polytitanocarbosilane fiber material.
~ 70% by weight zirconium oxide, 25 ~ 60% by weight silica and the remaining amount of sodium aluminate, an inorganic adhesive is dispersed or dissolved in water and applied on the inner surface of the mold.
The polytitanocarbosilane fiber material is placed on it in a fine state or as a group of long monofilaments or in the form of a woven or knitted fabric, and is pressed and attached, and moisture is removed at a temperature within the range of room temperature to 90 ° C. Then, it is cured at 100-350 ℃, and the total thickness of the fiber material and adhesive coating is 0.5-15mm.
The present invention also relates to a method for producing a casting mold having a polytitanocarbosilane fiber material coating, wherein

The casting mold that can be used in the present invention is a commonly used iron or copper alloy. In the present invention, the inner surface of the mold is not limited to the inner surface of the mold body, but may be a sprue, a riser,
The meaning includes the inside of the hot water.

The adhesive used in the present invention is composed of 35 to 70% by weight of zirconium oxide, 25 to 60% by weight of silica and the balance of sodium aluminate. When the content of zirconium oxide is more than 70% by weight, the adhesive strength to copper and stainless steel decreases, and when it is less than 35% by weight, the heat resistance becomes insufficient. If the amount of sodium aluminate added is small, the adhesiveness is poor, and if it is too large, aluminum silicate is produced during the production of the adhesive to form a bond, which makes the production of the adhesive difficult. It has been found that 25 to 60% by weight of silica is advantageous in relation to other components.

This adhesive exhibits a heat resistance of 1300 ° C. after curing.
Here, the curing means a heat treatment for curing the adhesive to the extent that it does not reach firing.

The chemical structure of the polytitanocarbosilane fibers used in the present invention as well as the process and properties are described in "Chemistry and Industry" above.

The role of this fibrous material is to improve the heat resistance, wear resistance and releasability of the mold. The fibers of this fiber material are
Although it depends on the dimensional accuracy of the mold and the molding used, those having a diameter of 8 μm to 5 mm are advantageous. However, even thicker fibers can achieve the object of the present invention. The fiber material may be in the form of short fibers, long fibers, woven fabric or knitted fabric, and may be in any form as long as it can be uniformly distributed on the inner surface of the mold.

The adhesive used in the present invention causes irregularities in the coating film due to rapid evaporation of water, so in order to avoid this, air drying or drying at a temperature up to about 90 ° C. for 20 minutes to 3 hours is performed. It is advantageous to carry out the curing at 100 to 350 ° C. for 20 minutes to 3 hours. At a temperature higher than 350 ° C, residual water has a bad effect on the surface of the coating film, and the adhesive coating film is baked, causing shrinkage and cracking. Moreover, sufficient curing cannot be performed below 100 ° C.

The total thickness of the fiber material and adhesive coating is 0.5, as described above.
~ 15mm. If it is thinner than 0.5 mm, it is not possible to impart sufficient heat resistance to the base metal, and if it is thicker than 15 mm, it becomes difficult to utilize the properties (thermal conductivity) of the base metal and the dimensional stability of the mold is maintained. It will be difficult. The thickness of the adhesive coating film is that the original function of the heat-resistant adhesive used in the present invention is to bond the fiber material to the base metal, and a thickness that fulfills this function is sufficient. The thicker the fiber, the thicker the fiber material. Generally, the thicker the adhesive coating is, the thicker the fiber is to achieve the purpose of adhesion, and the thinner the fiber is, the thinner the adhesive coating is sufficient.

An advantageous embodiment of the production of the casting mold of the present invention is as follows: First, an inorganic adhesive dispersion (concentration of 50 to 95% by weight) dispersed in water is applied to the inner surface of the mold, that is, the main body. It is applied to the inner surface, sprue, riser, riser, etc. with a thickness of 100 to 500 μm, especially 200 to 400 μm, and a fine polytitanocarbosilane fiber material with a thickness of 8 μm to 5 mm is applied to the adhesive application surface. Apply by pressing with a uniform distribution and optionally spraying the same adhesive dispersion as above on the fibrous material, drying at room temperature to 90 ° C for 1 hour or more, then at a temperature of 130-350 ° C. Cure.

The mold having the polytitanocarbosilane fiber material-containing coating of the present invention has sufficient heat resistance required for casting, and also has excellent abrasion resistance, and a molded body is molded from the mold after casting. The release property when taking out is also excellent. Furthermore, even if molding is performed for 10,000 shots without using the soft coating mold, the surface condition of the molded product does not become abnormal, and the molded product has excellent durability enough to withstand use.

The invention is explained in greater detail below with the aid of examples: Example 1 Adhesive consisting of 64.0% by weight zirconium oxide, 31.2% by weight silica and 4.8% by weight sodium aluminate 5
Disperse 0 g in 15 ml of water. This dispersion is applied to the inner surface of the mold of a copper alloy mold for automobile engine casing with a wet coating thickness of 300 μm and dried at room temperature for 1 hour.

Polytitanocarbosilane (Tyranno fiber, manufacturer: Ube Industries, Ltd.) fine fibers with a length of 3 mm and a thickness of 20 μm were adhered and pressure-regulated on this adhesive coating film in a uniform distribution, and the same as above. Spray the adhesive liquid. Then at a temperature of 85 ° C 1
Dry for an hour, then cure for 1 hour at a curing temperature of 150 ° C. The total coating thickness is 1,000 μm.

The casting mold produced in this way was used for casting the casing of an automobile engine while being cooled to 350 to 400 ° C. Even after 10,000 shots, the surface did not change and the surface condition of the molded product was good. Met. Mold release is very easy.

Example 2 Example 1 is repeated. However, as an inorganic adhesive aqueous dispersion, a dispersion of 50 g of 38.7% by weight zirconium oxide, 56.5% by weight silica and 4.8% by weight sodium aluminate in 17 ml of water and a tyranno having a thickness of 30 μm are used. The only difference is that a woven fabric of fibers is used.

The casting mold produced in this way was used for casting the casing of an automobile engine while being cooled to 350 to 400 ° C. Even after 10,000 shots, the surface did not change and the surface condition of the molded product was good. Met. Mold release is very easy.

Comparative Example A casting test is performed on a conventional copper alloy mold for an automobile engine casing that is not coated with polytyranocarbosilane fiber material. At that time, after performing 8,000 shots while applying a coating with a commercially available mold-type agent (ceramic kneaded into water glass) every 200 shots, the mold surface was worn out and became unusable. It was

[Effects of the Invention] The casting mold of the present invention has excellent heat resistance, abrasion resistance, and mold releasability as compared with conventional molds, and the complexity of performing coating can be omitted, which is excellent. It is durable and its contribution to the industry is remarkable.

Claims (2)

[Claims] 1. A polytitanocarbosilane fiber material is attached to an inner surface of a mold by an inorganic adhesive, and the inorganic adhesive is 35 to 70% by weight of zirconium oxide, 25 to 70% by weight.
It has a composition of 60% by weight of silica and the balance of sodium aluminate, and the total thickness of the fiber material and the adhesive coating film is 0.
A casting mold with a coating containing polytitanocarbosilane fiber material, characterized in that it is 5 to 15 mm. 2. Zirconium oxide, 35 to 70% by weight, 25 to 60
A liquid obtained by dispersing or dissolving an inorganic adhesive having a composition of wt% silica and the remaining amount of sodium aluminate in water is applied to the inner surface of the mold, and the polytitanocarbosilane fiber material is applied in a fine state on it. Lay as a group of long monofilaments or in the form of a woven or knitted fabric, press and paste, remove moisture at a temperature in the range of room temperature to 90 ° C, then 100-350
A method for producing a casting mold having a polytitanocarbosilane fiber material coating, wherein the total thickness of the fiber material and the adhesive coating film is 0.5 to 15 mm after curing at ℃.