JPH07303933A - Coating for die for casting - Google Patents

Abstract

PURPOSE:To provide the extremely excellent wear resistance, heat resistance, peeling stability, durability and the excellent releasability of a cast product in using the die. CONSTITUTION:The coating for a die for casting is manufactured with the powder mixture having the composition consisting of, by weight, >=20% zirconium oxide, 1-10% sodium aluminate, 2-15%, more specifically, 4-10% yttrium in terms of zirconium oxide and the balance silica, thc water dispersing heat resistant composition consisting of sodium silicate where a small amount of water is added, and the heat resistant fiber in a combined manner.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a casting die coating which exhibits excellent wear resistance, heat resistance, peeling stability, durability, and good mold releasability of a cast product when the die is used. Regarding things.

[0002]

2. Description of the Related Art Recently, adhesives mainly composed of inorganic components have been studied. For example, Japanese Examined Patent Publication (Kokoku) No. 50-33491 discloses that a mixture of finely divided high-purity zirconium oxide, colloidal silicic acid, and sodium aluminate in an amount of 2 to 10% by weight based on the total weight of these is fired at 1000 ° C. or higher and finely ground. Disclosed is a method for producing a high heat-resistant adhesive composition, which is obtained by The adhesive produced by this method has a low curing temperature, and it is reported that 250 to 350 ° C is sufficient.

The present inventor has found that by using this inorganic adhesive composition, a heat resistant fiber such as potassium titanate can be obtained.
By pasting or applying (K ₂ Ti ₆ O ₁₃ ) fiber, polytitanocarboxysilane fiber, and carbon fiber to the inner surface of the mold, we succeeded in significantly improving the life of the mold (
Japanese Patent Application Nos. 63-313755 and 63-323609). Further, a heat resistant sheet using the above adhesive composition was also provided (see Japanese Patent Application No. 1-13308).

[0004]

However, the present inventor has found that the above-mentioned adhesive composition has a problem in stability after curing and the cured coating film is relatively peeled off at a low cost. Therefore, studies were conducted to improve this stability, and by adding yttria, it showed better stability than the adhesive described in Japanese Examined Patent Publication No. 33491/1975 and, after drying, had significantly excellent abrasion resistance and peeling. It was found that an adhesive film (or coating film) having stability and thermal shock resistance can be obtained. The present invention is 20% by weight
The above zirconium oxide, 1 to 10% by weight of sodium aluminate, and 2 to 15% based on zirconium oxide.
Water-dispersible, heat-resistant composition, characterized in that it consists of a powder mixture containing by weight, in particular from 4 to 10% by weight, yttria and the balance being silica, and sodium silicate with a minor addition of water. And by further using it in combination with a heat-resistant fiber material, the coating for a casting mold produced has excellent wear resistance, heat resistance, peeling stability, durability, and
It has been found that when the mold is used, it exhibits good mold release properties.

The heat-resistant composition used in the present invention is 20% by weight.
Above all, in particular 25-70% by weight zirconium oxide, 1-10% by weight, in particular 2-5% by weight sodium aluminate and 2-15% by weight, based on zirconium oxide, especially
40-50 parts by weight of a powder mixture containing 4-10% by weight of yttria and the balance being silica with a small amount of water added
It is a composition obtained by adding sodium silicate (based on 100 parts by weight of the above powder mixture). If yttria is less than 2% by weight based on zirconium oxide, a sufficient stabilizing effect cannot be obtained, and if it is more than 15% by weight based on zirconium oxide, no additional effect can be expected. It is uneconomical to use excessively because it is expensive. If the zirconium oxide content is less than 20% by weight, the adhesion force and the gradient function between the ceramic layer and the substrate (for example, the base metal) will be insufficient. The composition can optionally further comprise heat-resistant pigments, such as inorganic pigments, such as iron oxides, titanium dioxide, etc., which do not have a detrimental effect during and after curing. This composition exhibits a heat resistance of 1300 ° C after curing.

The composition used in the present invention causes unevenness 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. The curing is advantageously performed at about 200 to 350 ° C for 20 minutes to 3 hours. At higher temperatures, residual water has an adverse effect on the surface of the coating film, and at lower temperatures, sufficient curing cannot be achieved.

The composition for use in the present invention is prepared by applying the composition to a substrate and, when it is used as an adhesive composition, combining with the substrate to be bonded, removing water from room temperature to 90 ° C. Curing reaction at 350 ℃.

Heat-resistant short fibers such as potassium titanate (K ₂ Ti ₆ O ₁₃ ) fibers and polytitanocarboxysilane are added to an aqueous dispersion prepared by adding water to the composition up to a water content of up to 20% by weight. A coating for a casting mold obtained by dispersing at least one kind selected from the group consisting of fibers, carbon fibers and whiskers, coating it on the inner surface of the mold, and curing it as described below is very excellent. Wear resistance,
Shows heat resistance, peeling stability, durability, and good mold releasability of cast products when using molds. The heat-resistant fibers used in this case are particularly advantageous from the viewpoint of dispersibility in that they have water-dispersible short fibers, for example, a length of 5 to 200 μm and a diameter of 0.05 to 5 μm.

After the coating on the inner surface of the mold, the coating temperature is 90 ° C from room temperature.
C. to remove moisture and cure at 200 to 350.degree. C. to cure. Therefore, the present invention is based on 20% by weight or more of zirconium oxide, 1 to 10% by weight of sodium aluminate, and 2 to 15% by weight based on zirconium oxide.
% Of yttria and the balance is silica, and a water-dispersible, heat-resistant composition consisting of a powdered mixture of sodium silicate with a small amount of water added with water up to a water content of up to 20% by weight. Potassium titanate (K
₂ Ti ₆ O ₁₃ ) fiber, polytitanocarboxysilane fiber, carbon fiber, ceramic fiber and other whiskers selected from the group consisting of dispersion of at least one kind of heat-resistant short fiber, the dispersion is the inner surface of the mold. Apply the same heat resistant composition as above to remove moisture from room temperature to 90 ° C and 2
The present invention relates to a coating for a casting mold that has undergone a curling reaction at 00 to 350 ° C.

The base metal of the mold used in the present invention can be any available metal such as copper, copper alloys, steel, aluminum, aluminum alloys, magnesium, magnesium alloys and the like. In particular, non-ferrous metals such as copper, copper alloys, aluminum, aluminum alloys, magnesium and magnesium alloys, which have a low melting point and are easily processed, can be used as a mold in the composition of the present invention. Is amazing.

Among the heat-resistant short fibers that can be used in the present invention, potassium titanate fiber is the inorganic material research laboratory research report No. 34.
No., "Study on Synthesis of Potassium Titanate Fiber," Science and Technology Agency, 1982, pp. 1-37. The role of this fiber is to improve the heat resistance, wear resistance and releasability of the mold. This fiber is from 5 to 200 μm, especially 10
~ 50 μm length and 0.05-5 μm, especially 0.1-1 μm
Fine fibers having a diameter of 10 are preferred. The amount of potassium titanate fiber added to the aqueous dispersion of the heat-resistant composition of the present invention is advantageously 2 to 30% by weight.

Another subject of the invention is the addition of potassium titanate (K ₂ Ti ₆ O ₁₃ ) to an aqueous dispersion of the coating composition according to the invention, to which water has been added up to a water content of up to 20% by weight. fiber,
A dispersion in which at least one kind of heat-resistant short fibers selected from the group consisting of polytitanocarboxysilane fibers, carbon fibers, ceramic fibers and other whiskers is dispersed in a heat-resistant cloth at 50 to 400 μm, particularly 200 to 250
It is also a sheet coated with a dry coating thickness of μm and a coating for a casting die in which the sheet is stuck to the inner surface of the die with the composition used in the present invention.

The heat-resistant cloth material used in the present invention may be any one that can favorably coat the aqueous dispersion of the coating composition of the present invention. The cloth-like material includes a non-woven fabric, a woven fabric or a knitted fabric made of carbon fiber, tyranno fiber, alumina fiber, silicon carbide fiber, and the thickness thereof is not particularly limited,
Relatively thin 100 when precision is required in the field of use
It is preferably about 1000 μm.

Further, in the present invention, the above-mentioned heat-resistant cloth is impregnated with a coating composition in an amount of up to 20% by weight depending on the case, and is adhered to the inner surface of the mold with the heat-resistant adhesive of the present invention. It also relates to a method for coating a casting mold and the coating thus obtained, characterized in that it is dried at room temperature to 90 ° C to remove water and cured at 200 to 350 ° C.

An embodiment of applying the composition used in the present invention to a casting mold is as follows: First, up to 20% by weight
2 to 15% by weight of potassium titanate short fibers, based on the composition, is dispersed in the composition used in the present invention to which water has been added up to the water content of 1. It is dried at room temperature to 90 ° C for 1 hour or more, and then cured at 200 to 350 ° C. The coated mold inner surface is that of the mold sprue, riser, riser and mold body.

The mold having the coating containing potassium titanate fibers produced in this manner has sufficient heat resistance required for casting, and also has excellent wear resistance and a molded product after casting. It also has excellent releasability when removing from the mold. 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 composition used in the present invention may be added to the above heat-resistant cloth in an amount of 50 to 400 μm, if necessary after adding a small amount of water.
It is also possible to use a heat-resistant sheet coated with a dry coating film thickness of m 3 for a die coating.

The present invention further pours an aqueous dispersion containing the above composition together with at least one kind of the above heat-resistant short fibers onto a releasable water-permeable substrate such as a wire net, and the like at room temperature to 90 ° C. Heat-resistant fiber-containing sheets obtained by removing water and peeling can also be used for the purpose of the present invention. The sheet is cured when used.

The thickness of these sheets is not particularly critical, but can be appropriately determined depending on the application. For example, when it is attached to the inner surface of a casting mold, it is advantageous that the thickness is about 50 to 1000 μm. However, in the case where the dimensional stability is not required, of course, the thickness may be further increased.

Two advantageous embodiments of the use of the composition according to the invention for the production of sheets are described below: First,
5 to 15% by weight, based on the composition, in a dispersion of the composition according to the invention, to which water has been added up to a water content of up to 20% by weight.
% Potassium short titanate short fibers and 5 to 15% by weight of other ceramic fibers, for example alumina fibers,
Pour an appropriate amount of this dispersion onto the filter paper of a suction filter, remove most of the water content by suction filtration, and dry at a temperature from room temperature to 90 ° C for about 1 to 3 hours.

The thickness of the dry sheet obtained by pouring once is up to about 500 μm. In order to produce a thicker sheet, the above pouring and water removal operations are repeated, and then a curing reaction is performed.

In the second embodiment, potassium titanate short fibers and other ceramic fibers such as alumina fibers are dispersed in water, an appropriate amount of this dispersion is poured onto the filter paper of a suction filter, and the water content is removed by suction filtration. In the form of a sheet except for most of the above, spraying an appropriate amount of the aqueous dispersion composition of the present invention thereon, re-spraying the same aqueous dispersion after a little drying at room temperature, and from 1 to 3 at a temperature from room temperature to 90 ° C. Dry for about an hour. These sheets should be used, for example, when pasting
Cure at 200-350 ℃ for about 1-3 hours.

The obtained sheet can be appropriately attached to a place or member where heat resistance up to about 1300 ° C. is required.

[0024]

EXAMPLES The invention is explained in greater detail below with the aid of examples: Preparation of compositions Example 1 60 parts by weight zirconium oxide, 40 parts by weight silica, 5 parts by weight sodium aluminate and 4.8 parts by weight. To 50 g of a powder mixture consisting of parts by weight (corresponding to 8% by weight based on zirconium oxide) of yttria was added 5 ml of water.
Add g of sodium silicate and knead to make viscous paste.

Example 2 50 g of a powder mixture consisting of 50 parts by weight of zirconium oxide, 55 parts by weight of silica, 5 parts by weight of sodium aluminate and 2 parts by weight (corresponding to 4% by weight, based on zirconium oxide) of yttria. 20g with 5 ml of water added to
Sodium silicate is added and kneaded to form a viscous paste.

Example 3 50 g of a powder mixture consisting of 40 parts by weight zirconium oxide, 65 parts by weight silica, 5 parts by weight sodium aluminate and 2 parts by weight (corresponding to 5% by weight, based on zirconium oxide) yttria. 24g with 4 ml of water added to
Sodium silicate is added and kneaded to form a viscous paste.

Example 4 50 g of a powder mixture consisting of 30 parts by weight zirconium oxide, 65 parts by weight silica, 5 parts by weight sodium aluminate and 1.5 parts by weight (corresponding to 5% by weight, based on zirconium oxide) yttria. To which was added 4 ml of water 22
Add g of sodium silicate and knead to make viscous paste. Example of Use of Composition Example 5 50 g of the paste described in Example 1 was mixed with 5 ml of water, and 10 g of potassium titanate fiber having an average length of 20 μm and an average diameter of 0.9 μm was dispersed in the aqueous dispersion. This dispersion
Thickness 500μm Carbon fiber woven fabric wet coating thickness 300μ
Apply to a thickness of m (dry coating thickness; approx. 215 μm). this
Dry at 90 ° C for 1 hour, then cure at 250 ° C for 2 hours.

Next, using 50 g of the composition of Example 1,
The above-mentioned cured carbon fiber woven fabric is attached to the inner surface of the copper alloy mold for the casing of the automobile engine, the inner surface of the sprue and the like. This is also dried at 90 ° C for 1 hour and then 250
Cure for 2 hours at a curing temperature of ℃.

The above-prepared mold thus produced was
When it was used for casting a casing of an automobile engine while being cooled to 400 ° C, the surface did not change even after 10,000 shots, and the surface condition of the molded product was good.
Mold release is very easy.

Example 6 Using 50 g of the paste-like material described in Example 2, a thickness of 500 μm was obtained.
m Carbon fiber fabric is attached to the inner surface of the copper alloy mold for automobile engine casing, the inner surface of the sprue, etc. This at 90 ℃
Dry for 1 hour and then cure for 2 hours at a curing temperature of 250 ° C.

The above-prepared mold thus produced is heated to 350
When it was used for casting a casing of an automobile engine while being cooled to 400 ° C, the surface did not change even after 10,000 shots, and the surface condition of the molded product was good.
Mold release is very easy.

Example 7 50 g of the composition described in Example 2 was mixed with 4 ml of water, and 6 g of potassium titanate fiber having an average length of 20 μm and an average diameter of 0.9 μm and 4 g of alumina fiber were dispersed in the aqueous dispersion.

This dispersion was applied to the inner surface of a steel mold,
Dry at 90 ° C for 1 hour and cure at 250 ° C for 2 hours. A dry coating thickness of about 230 μm is obtained. Using the above mold produced in this way, when used to cast the casing of an automobile engine, even after 10,000 shots,
The surface did not change and the surface condition of the molded product was good. Mold release is very easy. Sheet Production Example 8 6 g of potassium titanate fiber having an average length of 20 μm and an average diameter of 0.9 μm and 4 g of alumina fiber were further dispersed in an aqueous dispersion obtained by adding 5 ml of water to 50 g of the dispersion of Example 3. A 100 mm id nutche is lined with filter paper, the dispersion of Example 1 is sprayed onto it and most of the water is removed by suction filtration. A sheet with a thickness of about 1 mm is obtained when wet. Take it out with the filter paper and place it on a fresh filter paper at room temperature 1
Air dry for hours. The resulting sheet has a thickness of about 0.6 mm.

Example 9 50 g of the dispersion of Example 1 is spray coated onto a 550 μm thick polytitanocarboxysilane fiber fabric with a wet coating thickness of 300 μm and dried at 90 ° C. for 1 hour. Dry coating thickness 265 μm
A sheet having a coating layer of

When cured at 300 ° C., this sheet withstands temperatures up to 1300 ° C. Example 10 To a dispersion obtained by adding 5 ml of water to 50 g of the dispersion of Example 4, 6 g of potassium titanate fiber having an average length of 20 μm and an average diameter of 0.9 μm and 4 g of alumina fiber are added and mixed. Pour this mixture into a very fine mesh wire mesh, 90 ° C
Dry for 1 hour. After that, this coating film is peeled off from the wire net to obtain a sheet. The sheet produced in accordance with Example Example 11 Example 8 Using the sheet, in dispersion 50g described in Example 4, the casing copper alloy mold automobile engine (The mold No. Sho 63-306824 However, the structure is as follows: Ni plating layer on the inner surface of the mold,
A copper mold having three layers of Co / Mo / Cr-alloy coating layer as an intermediate layer and Al ₂ O ₃ / ZrO ₃ -porous ceramic coating layer as an outer layer in this order. Paste the above sheet instead) and the inside of the sprue. After drying at 90 ° C for 1 hour, it is cured in a drying chamber at a temperature of 250 ° C.

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

[0037]

The mold coating of the present invention exhibits excellent wear resistance, heat resistance, peeling stability, durability, and good mold releasability of a cast product when the mold is used. Therefore, the contribution of the heat-resistant composition of the present invention to the industry is remarkable.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area C09J 1/02 JAC

Claims (4)

[Claims] 1. 20% by weight or more of zirconium oxide,
A water-dispersible composition consisting of 1-10% by weight of sodium aluminate and 2-15% by weight of yttria based on zirconium oxide and a balance of silica, and sodium silicate with a small addition of water. Potassium titanate (K ₂ Ti ₆ O ₁₃ ) fiber, polytitanocarboxysilane fiber, carbon fiber, ceramic fiber in an aqueous dispersion in which water is added to the heat-resistant composition of up to 20% by weight. And at least one kind of heat resistant short fibers selected from the group consisting of other whiskers is applied to the inner surface of the mold with the same heat resistant composition as described above, and moisture is removed at room temperature to 90 ° C. And casting mold coating which has been subjected to a curling reaction at 200 to 350 ° C. 2. Zirconium oxide of 20% by weight or more, 1 to
A water-dispersible, heat-resistant composition consisting of 10% by weight sodium aluminate and a powder mixture containing 2-15% by weight of yttria, based on zirconium oxide, the balance being silica, and sodium silicate with a small amount of water added. Titanate (K ₂ Ti ₆ O ₁₃ ) fibers, polytitanocarboxysilane fibers, carbon fibers, ceramic fibers and others in aqueous dispersions with water added up to a maximum water content of 20% by weight After the dispersion of at least one kind of heat-resistant short fibers selected from the group consisting of whiskers was applied to the heat-resistant cloth, the water content was removed at room temperature to 90 ° C. A sheet with a dry coating thickness was applied to the inner surface of the mold with the same heat-resistant composition as described above, then water was removed at room temperature to 90 ° C, and a curing reaction was performed at 200 to 350 ° C to attach the sheet. Casting mold coatings was. 3. Zirconium oxide of 20% by weight or more, 1 to
A water-dispersible, heat-resistant composition consisting of 10% by weight sodium aluminate and a powder mixture containing 2 to 15% by weight of yttria, based on zirconium oxide, and the balance being silica, and sodium silicate with a small amount of water added. Heat-resistant cloth is impregnated with the heat-resistant composition, the same heat-resistant composition is applied to the mold surface, water is removed at room temperature to 90 ° C, and
A method for coating a casting mold, which comprises performing a curing reaction at 350 ° C. 4. A coating for a casting mold produced by the method according to claim 3.