KR100398705B1 - Coating material, its production method and coating process for metal mold casting of high melting point alloys. - Google Patents

Abstract

The present invention is used to protect the mold when casting a high melting point metal into a metal mold and to facilitate casting, fire resistance, adhesiveness, mold release property and coating workability. It is related with this excellent figure material, its manufacturing method, and a coating method.

To this end, the present invention, in order to exhibit excellent performance in the die casting of a high melting point metal of the melting point of the metal to be cast of more than 1000 ℃, the shape material is chamotte powder or α-cristobalite whose main component is alumina having a purity of 98% or more Figure base material consisting of a mixed powder of quartz and SiO ₂ and phosphate-based binders, additives of zinc nitrate or aluminum nitrate, and diluents It is composed of distilled water, which is composed of a method of mixing a figure base material powder, a caking additive, a diluent material, and an additive material in an appropriate ratio, and applying the manufactured figure material to a mold. There is a characteristic.

Description

Protective mold for metal molds used in the casting of high melting point metals to metal molds, and its manufacturing method and coating method {Coating material, its production method and coating process for metal mold casting of high melting point alloys.}

There are many kinds of molds necessary for the manufacture and production of castings, but they are roughly divided into sand casting (sand casting) casting and die casting (metal casting) casting. Among them, the mold casting method does not use sand, so it is a casting process that has great advantages such as improvement of environment, reduction of functional manpower, simplification of post-treatment process, improvement of recovery rate, ease of automation, and reduction of investment cost. One of the most important factors in this mold casting method is the life extension of the mold and the casting workability.

Although the adequacy of material and design of mold is important for extending the life of the mold, it is possible to effectively extend the life of the mold by alleviating thermal shock of the mold by applying and protecting the mold with the appropriate mold figure during casting. have. This figure is important because the higher the melting point of the metal to be cast (in the case of a high melting point metal of 1000 ℃ or more) the greater the thermal shock received during the casting operation, the mold life and casting depending on the type and characteristics of the shape Work is greatly affected.

Conventionally, as a caking material, water glass, clay, bentonite, etc. are used as the caking material, and graphite, diatomaceous earth, vermiculite, alumina, refractory clay, etc. are used alone or in combination, and as additives, such as calcium permanganate, borax, aluminum It is manufactured using powder, ferrosi silicon, various cellulose, etc., but it is used for sand casting or mold casting of relatively low melting metal such as aluminum alloy. Due to the phenomenon that the figure base material is easily peeled from the mold is appearing has not been utilized.

Since the performance of the shape material depends on workability, casting quality, and the life of the mold, it is very important to manufacture good quality shape material. In order to develop such a high quality figure material, first, it combines chemically well with the metal surface of the mold and adheres aggregate particles to the metal surface to form a strong figure film. After the fine powder having a porous structure to effectively block the heat conduction and radiant energy from the molten metal, and the third coated film must not have hygroscopicity, the fourth workability must be overcome to overcome the technical problems.

In order to achieve the above object, the present invention, the melting point of the metal to be cast can exhibit excellent performance in the mold casting of high melting point metal of more than 1000 ℃, the figure material is chamotte powder or α of the main component is alumina having a purity of 98% or more -Figure base material consisting of a mixed powder of cristobalite and quartz (SiO ₂ ) and phosphate-based binders, additives of zinc nitrate or aluminum nitrate, and It is composed of distilled water, which is a diluent, which is a method of mixing a figure base material powder, a caking additive, a diluent material, and an additive material in an appropriate ratio, and applying the manufactured figure material to a mold. It is characterized by being composed of.

1 is a manufacturing process of the figure of the present invention

Figure 2 is a coating process process diagram of the figure of the present invention

3 is the surface of the figure layer after figure

<Description of main parts of drawing>

1: plastic container 2: graphic material

3: metal salt 4: distilled water

5: stirrer 6: phosphoric acid

7: mold 8: sandblasting machine

9: heating torch 10: spray gun

11: heating furnace

The figure of the present invention comprises a figure base material of various refractory materials, a caking agent, an additive, a diluent, and the like.

The figure base material is a thermal barrier material to protect the mold surface from high temperature molten metal and consists of fine ceramic and metal oxide powder. The caking material chemically bonds to the metal surface and adheres the figure base material to the metal surface. , Additives reinforce the function of the caking additives, and diluents are the constituent materials that control the concentration and viscosity of the constituent materials to facilitate the shape work. DETAILED DESCRIPTION Hereinafter, the detailed description of the invention will be described with reference to the accompanying drawings and examples.

The figure base material of the present invention is a fine refractory powder, which is two kinds of chamotte powder whose main component is alumina having a purity of 98% or more, or a mixture powder of? -Cristobalite and quartz. Chamotran is a fired clay or a mixture of other refractory raw materials mainly fired and pulverized. The main component is Al ₂ O ₃ -SiO ₂ -based, fire resistance is 1580 ℃ or higher, and alpha-cristobalite is a form of silicon dioxide which is a natural acid. It is stable from 1470 ° C to 1700 ° C, which is a melting point. The average particle diameter of the figure substrate used in the present invention is about 14 μm for chamotte powder, 9.92 μm for α-cristobalite, and 24.45 μm for quartz powder.

The caking additive of the present invention is a kind of phosphate caking additive, with phosphoric acid and phosphate having a concentration of about 85%. It produces the following figure film forming function. The mechanism of generating phosphate film is a kind of corrosion reaction, and this corrosion product is used for the film. Since phosphoric acid (H ₃ PO ₄ ) is a tribasic acid, there are Me (H ₂ PO ₄ ) ₂ phosphate monophosphate, MeHPO ₄ diphosphate, and Me ₃ (PO ₄ ) ₂ triphosphate. Here, Me represents bivalent metals, such as Zn, Mn, Fe, and Ca. Of these, phosphate is water soluble, but dissociates as follows:

Me (H ₂ PO ₄ ) ₂ MeHPO ₄ + H ₃ PO ₄

3MeHPO ₄ Me ₃ (PO ₄ ) ₂ + H ₃ PO ₄

When an aqueous solution of about 3% of Me (H ₂ PO ₄ ) ₂ is heated to 97 to 99 ° C., it is dissociated as described above. Of these, when iron is immersed in free phosphoric acid, H ₃ PO ₄ , the following reaction is carried out.

2H ₃ PO ₄ + Fe → Fe (H ₂ PO ₄ ) ₂ + H ₂

In this way, iron is dissolved in the liquid while hydrogen is generated. The produced MeHPO ₄ or Me ₃ (PO ₄ ) ₂ is insoluble and thus precipitates on the fresh iron surface at the instant of formation, thus forming a film. PH of the caking additive of this invention is 1.84, and specific gravity is about 1.12.

The additive of the present invention is to increase the action of the caking additive may be used a variety of metal salts, the present invention uses a metal salt of zinc nitrate or aluminum nitrate.

Diluent material of the present invention is to distilled water to smooth the work and to control the characteristics in the present invention uses distilled water as the diluent.

The manufacturing method of the figure having the above components is as shown in Figure 1, as shown in Figure 1 (a) of the refractory base material which is a chamotte powder composed of alumina having a purity of 98% or more, or a mixed powder of α-cristobalite and quartz Injecting the powder (2) into the plastic container (1) and the step of injecting the metal salt (3), such as zinc nitrate or aluminum nitrate, weighed as shown in (b) of FIG. ) Distilled water (4) weighed as in the diluent material in the same container and the mixing of the raw material introduced using the stirrer (5) as shown in Figure 1 (a) and the phosphoric acid weighed during stirring ( 6) is composed of the step of putting. The blending ratio of the figure base material, caking additive, additive and diluent has a ratio of (3 to 5): 1: (2 to 5): (13 to 17) when the caking additive is 1 by weight.

The figure work of the figure material manufactured by the above method is the same as FIG. 2, but it is necessary to be careful because it varies greatly depending on the surface state of the mold, the figure work is oil on the surface of the mold (7) as shown in (a) of FIG. B, a scale or the like is first processed in a shot blasting machine or a sand blasting machine 8 to improve adhesion of the shape material, and as shown in (b) of FIG. 2, the mold is heated by using the heating torch 9. Preheating to ˜250 ° C. and applying the mold material using a casting spray gun 10 having a large nozzle capable of forming a smooth figure layer as shown in FIG. As shown in (d) of FIG. 2, the figure surface is placed in a heating furnace 11 maintained at about 300 ° C., followed by heating and firing for about 2 hours.

The preheating condition of the mold affects the properties of the coated figured material and also promotes thermal decomposition of the figured binder. This mold preheating temperature is determined by the heat capacity of the mold and the pyrolysis temperature of the caking additive, but in practice, the preheating temperature is 200-250 ° C. in a normal mold (300 × 400 × 500 mm).

The use of casting nozzles with large nozzles for the application of mold materials increases wear resistance than those with spray nozzles with small nozzles. If the application amount is large under the conditions, evaporation of moisture in the mold material is delayed and a dense figure layer is formed. On the other hand, when the angle of the nozzle with respect to the mold surface is perpendicular to the coating surface during the coating operation, the best figure layer is obtained. Application of the inclined direction tends to form a figure layer having many uneven parts on the surface.

After the figure, it is desirable to heat the figure surface and bake it, because it is sufficient to thermally decompose the figure caking additive to prevent defects due to the generation of gas during the molten metal injection operation. When molten metal is re-injected into the mold after a long period of inactivity, the surface of the figure needs to be reheated.

<Example>

An embodiment in which the cast material, which is a high melting point metal, is molded by blending the above-described shape material of the present invention is as follows.

In manufacturing 100g of flakes, 15g of chamotte powder is 15g, 5g of phosphate binder is 5g, 10g of zinc nitrate is 10g as additive, and 70g of distilled water is used as diluent. Add 70 g of% to a plastic container and stir well as shown in (d) of FIG.

The figure manufactured by the above method is processed into a figure of 300 × 400 × 500 mm in a mold as shown in FIG. 2. First, sand blasting removes contaminants from the surface, and preheats to 250 ° C. using a heating torch. Then, after applying the mold material prepared by the above-mentioned method using a large casting spray gun, it puts in the heating furnace maintained at 300 degreeC, and it heats and bakes for about 2 hours.

Melt the cast iron to maintain the molten metal temperature at 1,300 ℃, prepare the injection molding by assembling the mold and inject the molten cast iron into the mold. When the solidification is completed, open the mold to take out the casting, then mold the mold again and inject the cast iron molten metal.

As a result of evaluating the performance of the cast iron molten metal as described above, even after repeated injection of the cast iron molten metal at 1300 ℃ 800 times continuously did not peel the figure layer, it was possible to maintain a good figure layer as shown in FIG. . This is because the figure material of the present invention chemically bonds well with the metal surface of the mold and adheres the aggregate particles well to the metal surface to form a strong figure film, and there is no heat melting and sintering by heat, and effectively blocks heat conduction and radiant energy from the molten metal. . In addition, the figure material of the present invention is very good figure workability because it becomes a good figure even through a simple spraying and firing work.

As described above, according to the present invention, the figure of the present invention bonds chemically well to the metal surface of the mold and adheres the aggregate particles to the metal surface to form a strong figure film. It cuts energy effectively, and the figure is very good even through simple spraying and firing.

Therefore, the use of the shape material of the present invention has the effect of improving the life of the mold in the mold casting of high melting point metal (for example cast iron) as well as the productivity and quality of the product significantly, so that high quality cast iron products can be manufactured at low cost. In addition, the existing mold manufactured items can be cast, so the ripple effect is very large.

Claims (3)

Protective mold for metal molds used in the casting of high melting point metals to metal molds. Shaped materials and binders made of various refractory materials. It consists of additives and diluents, and the figure base consists of two kinds of chamotte powder whose main component is alumina with purity of 98% or higher, or mixed powder of α-cristobalite and quartz. Is a kind of phosphate caking additive, which is composed of about 85% phosphoric acid and phosphate, and additives include zinc nitrate or aluminum nitrate. Diluent uses distilled water. A figure having a ratio of (3 to 5): 1: (2 to 5): (13 to 17) when the mixing ratio of the diluent is based on the caking additive as 1 by weight. A method of manufacturing a shape material having a composition and a compounding ratio of claim 1, wherein the shape-material powder weighed in a plastic container is added at the compounding ratio of claim 1, and the weighed caking additive is added to the same container at the compounding ratio of claim 1 and weighed. Adding distilled water to the same vessel at the mixing ratio of claim 1 as a diluent and mixing the raw material added by using a stirrer until the caking particles, which are solid grains, are completely dissolved in the diluent and no precipitation is observed in the solid; A method comprising the step of adding the weighed phosphoric acid during the stirring in the compounding ratio of claim 1. In the coating method of the mold material prepared by the method of claim 2, the oil or scale of the surface of the mold is first treated with a shot blast or a sand blast to improve adhesion of the mold material and the mold 200 to Preheating to 250 ° C, applying a shape material using a casting spray gun with a large nozzle to form a smooth figure layer, and heating the figure surface at about 300 ° C for 2 hours after the figure, Method consists of the steps of firing