JPS62158547A - Molding material for precision casting - Google Patents

Abstract

PURPOSE:To improve quality of molding material and to reduce production cost by adjusting water-crushed ferro-nickel slag having the specified wt% of MgO, FeO and CaO to less than the described grain size, to form the molding material. CONSTITUTION:The slag by-produced at smelting for ferro-nickel is treated by the water-crushing method and selected as the suitable slag for its composition of >=30% MgO, <=13% FeO, <=5% CaO and adjusted to <=5mm for max. grain size. The slag material is used as the molding material by mixing with stucco material such as usual ZrO2-SiO2 series, etc., or this slag alone. This molding material has desired characteristics for strength, casting surface, etc., and good collapsibility and also, stable chemical composition and thermal expansion ratio. Further, as raw material is obtd. at low cost, the quality of mold is improved and molding cost is reduced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a mold material for precision casting that is used in precision casting by an investment casting method, provides a good casting surface, and has good mold release. be.

[Conventional technology and shortcomings]

A precision casting method called investment casting method is known and in practical use. That is, in this method, a wax turn of the same type as the cast product is first manufactured, a runner necessary for casting is provided in this wax R turn, and then assembled into a wax tree. Next, this wax tree is coated with multiple layers of refractory material, dried, and then heated to remove wax. Thereafter, the mold is preheated for firing, the molten metal is poured into the mold, the mold is cooled, the mold is removed, the cast product is taken out, and the product is finished and processed.

The method for coating the refractory is to soak the wax tree in a slurry of refractory/saunder to adhere the refractory, sprinkle it with powdered refractory, so-called stucco material, and then sand it. This immersion and sanding are repeated to form a mold having the desired degree of fire resistance and strong deformation.

Colloidal silica containing about 30% of 191 oz is generally used as the binder for the slurry, and as the material 1, fine powder with high refractory properties such as zircon or fused silica can be used. A surfactant, an antifoaming agent, and water are added to this refractory and ingu as necessary to adjust the viscosity to a desired value.

In addition, as stucco materials, ZrO2-8102 series, 5i
Various refractories such as n2 series, Al2O3 series, and Al2O35i02 series are used, and ZrO2-5i02 with an average particle size of about 300 yen mesh or less is especially used for the first layer that comes into direct contact with the molten metal and determines the surface properties of the cut material. system is widely used. From the second layer onwards, granular refractories with a particle size of 0.3 to 4.5 are used in consideration of desired strength, air permeability, disintegrability after casting, etc.

However, these refractories are generally molded by drying or firing natural minerals to adjust the particle size, or by crushing molten minerals at high temperatures. Mineral resources are becoming increasingly homogeneous, making it difficult for people to handle them, and there are problems such as they are expensive and have large variations in quality.Furthermore, they are difficult to disintegrate when molded, making it labor-intensive and time-consuming. There were such problems.

[Means for solving problems]

In order to solve the above-mentioned problems, the present inventors conducted various tests and research on various refractories, and as a result, the present inventors developed a method for converting slag of a specific composition, which is produced as a by-product during ferronickel smelting, into a specific particle size. The present invention was made based on the discovery that the adjusted material is not only a substitute for conventional refractories that have been heavily used, but also can exhibit even superior performance. That is, the present invention provides precision casting in which granulated ferronickel slag is made of granulated ferronickel slag containing (2) MgO at (2) weight percent, FeO at 13 weight percent or less, and CaO at 5 weight percent or less, with a maximum particle size of 5 mm or less. It is a mold material for

The mold material used in the present invention is slag which is a by-product of ferronickel smelting, and ferronickel smelting involves adding a reducing agent and a solvent as necessary. , the metal ferronickel containing about 204 N1 is separated and recovered by reduction melting in an electric furnace, melting furnace, rotary kiln, etc., and the by-product slag,
This process is carried out using methods such as water crushing, wind crushing, and dry crushing.

However, due to the smelting process, its chemical composition,
Mineral composition, particle size, etc. are different, but each is stable and 1. The amount of slag produced reaches over 100,000 tons, and the most produced slag is slag that is granulated by reduction smelting at about 1650°C using the electric furnace method (referred to as granulated air furnace slag). Their typical chemical composition is heavy tS, Mg028
~37%, peo7~[3chi, B 1oz45~5
5%, htzo5 1~aq6, CaO1~2%, mineral composition is forsterite (2ME
Q-8i02) 75" Approximately 60ts main foot, approximately 30% vitreous, the remainder is solid) (MgO, StO
), and the particle size distribution is as shown in the table below. These sluds are used as a solvent in steel smelting and as a silicon fertilizer, and are also used as roadbed material and in landfills.

Electric Furnace Granulated Slag Co., Ltd. is a product made by blending several types of magnets with slightly different compositions to a predetermined composition, reducing and dissolving the solution at high temperatures, and then quenching and crushing it in water, so the composition and intergranularity are stable. As shown in the attached figure, it has a high fire resistance, a low coefficient of thermal expansion, and an irregular shape similar to a crushed product, so if the particle size is adjusted appropriately, it can be used for precision casting. Can be used as stucco material.

Therefore, the granulated ferronickel slag in the present invention has Mg030% by weight or more, FeO13% by weight or less,
(Has a weight ratio of 5 or less and a maximum particle size of 5 or less.

-i, the chemical composition of ferronickel slag is MgO<30% by weight, FeO>13% by weight, OaO
>5% by weight, the melting point decreases and the fire resistance decreases.

Depending on the purpose of use, the particle size is determined by crushing with an impeller breaker, etc., and then sieving to obtain particles of 5 to 2 mm or 0.5 to 1.0 mm.
, 0.3w O,7rn, 0.05w0.3m
When crushing to 0.3 mm or more, it is better to crush with an impeller breaker etc. than with a ball mill etc. as the surface shape of the particles is irregular and the adhesion to the slurry is better. Preferably, if the maximum particle size exceeds 5n, sanding workability is poor, uniform adhesion to the slurry becomes difficult, and the strength of the mold decreases.

Furthermore, if ferronickel is not pulverized, but the solution is pulverized with air or poured onto a roadbed and slowly cooled, it is undesirable because it easily weathers and its strength is weakened, so granulated slag is used. It is.

For these reasons, it is necessary to use granulated ferronickel slag with the above composition and particle size, which can be used as a mold material superior to conventional products.

〔Effect of the invention〕

Since the present invention is a mold material made of granulated ferronickel slag with a specific composition and particle size, it can be used alone or in combination with conventionally used ZrO2-5iCh and A/203-8in2 stuff materials. In addition, as long as the mold material of the present invention is used in any layer during lamination, the dimensional accuracy of the product castings will be as good as conventional products, and the casting surface will be as good or better. The reeds and shape can be easily disassembled, and since it is an industrial product of ferronickel, its chemical composition, mineral composition, coefficient of thermal expansion, etc. are stable, and it can be obtained in large quantities at low cost. By appropriately selecting the mixing ratio with other materials and grain sizes, it is possible to mold a mold that has the desired performance, such as strength and casting surface, depending on the material and size of the casting, and is hard and resistant to wear. Therefore, even if it is fluidized during sanding, there is little generation of powder, so there is no need for undercutting, and excellent effects are recognized, such as less time and effort, good yield, and no harm caused by fine powder.

〔Example〕

Next, one embodiment of the present invention will be described.

Example 1 1) Composition of granulated ferronickel slag Table 1 shows the chemical composition of the granulated ferronickel slag used.

Table 1 2) Particle size distribution of stucco material Sand A, which is made by crushing the granulated ferronickel slag of the present invention and has a particle size distribution as shown in Table 2, is used as a stucco material.
, adjusted three types of stucco materials: Sun rB1 Sand C,
AJ20, which has been used conventionally. -5in2 series, Zr
O2-S ion based stucco material is also Sand D (AJsOs-Sin, series) with particle size distribution as shown in Table 2.
, Sand H (Al505-8101 series), Sun PF (
Three types of stucco materials were prepared: ZrO2-slo, system).

3) Slurry composition Colloidal silica (5iOa30%), Zro2
- SiC1g flower #350, A71103S
i Ox-based flour #200 and additives (surfactants, etc.) are used to prepare the primary powder in the proportions shown in Table 3.
A slurry for use in dry cleaning and a slurry for pick-up were prepared.

4) Preparation of wax tree A wax tree was prepared by attaching a runner to a plurality of cylindrical parts each having a diameter of 50 mm and a length of 110 mm.

5) Coating The wax tree prepared in 4) was immersed in the primary slurry prepared in 3) (hereinafter referred to as slurry A), and then coated with ZrO2E1102-based stucco material (hereinafter referred to as Sanr).
The first layer is coated by sanding a slurry for knock-up (hereinafter referred to as F), the second layer is coated in the same manner as the first layer, and the third and fourth layers are coated using a knock-up slurry (hereinafter referred to as F). After immersion in slurry B),
The stucco material B of the present invention (hereinafter referred to as sand B) is sanded and coated to form the fifth layer and the sixth layer.
The layers were formed by dipping in slurry IJ + B and then sanding stucco material A of the present invention (hereinafter referred to as sand A), and the seventh layer was formed by dipping in slurry BK without sanding. was formed.

6) Casting This mold was dried in the usual manner at a temperature of 22°C and a humidity of 50%, and then heated to 130°C to remove wax.
After preheating for firing to 1650°C, molten stainless steel was poured into the mold, and after cooling, it was dismantled using a knockout machine.

7) Visually inspect the casting surface of the casting obtained as a result of the test, measure the dimensional accuracy,
The difficulty of demolding was determined by measuring the time required for a knockout machine. These results are shown in Table 4.

Example 2 Using the same wax tree, slurry, and stucco material as in Example 1, the first and second layers were coated and formed in the same manner as in Example 1, and the third and fourth layers were coated and formed in the same manner as in Example 1. The layer is soaked in slurry BK, then sanded with 50% Sand B)'
Sanded and formed with 50% mixed stucco material,
The 5th and 6th layers are formed by dipping in Slurry B and then sanding with a mixed stucco material of 50% Sand A and 50% San PD, and the 7th layer is formed by sanding only by dipping in Slurry BK. Even if the molded product was not formed, it was treated and cast in the same manner as in Example 1, and the obtained casting was subjected to the same tests as in Example 1. The results are shown in Table 4.

Example 3 Using the same wax tree, slurry and stucco material as in Example 1, the first and second layers were made of sla IJ +
After soaking in A, the stucco material of the present invention (hereinafter referred to as San PC
b) The 31st and 4th layers are formed by sanding with a mixed stucco material of 30% Sand F' and 70% Sand F'.
The 6th and 7th layers are formed by dipping in Sura 17 ++ B and then sanding with Sand B.
After dipping in B, it was formed by sanding with sand yh.

This was treated and cast in the same manner as in Example 1, and the obtained casting was subjected to the same tests as in Example 1. These results are shown in Table 4.

Example 4 Using the same wax tree, slurry and stucco materials as in Example 1, the first and second layers were formed by dipping in slurry A and then sanding with sand C, and the third and second layers were formed by dipping in slurry A and then sanding with sand C. The fourth layer was immersed in Sura IJ-B and then soaked in Sun F B
The 5th and 6th layers were dipped in slurry B and then sanded with a mixture of 30% SanrA and 70% Sand D, and the 7th layer was formed by simply immersing it in slurry IJ m H without sanding.

After drying and removing wax, the mold was fired at soo'c, and a copper alloy was cast at 1200°C. The obtained castings were subjected to the same tests as in Example 1. The results are shown in Table 4. Shown below.

COMPARATIVE EXAMPLE Using the same wax tree, slurry and stucco materials as in Example 1, the first and second rfI were coated with slurry +7
The third and fourth layers are formed by dipping in slurry B and then sanding with sand E, and the fifth and sixth layers (d
The seventh layer was formed by dipping it in Slurry IJ-B and then sanding it, and the seventh layer was formed by just dipping it in Slurry +B without sanding.

This was treated and cast in the same manner as in Example 1, and the obtained casting was subjected to the same tests as in Example 1. The results obtained are shown in Table 4.

[Brief explanation of drawings]

The figure is a diagram showing the relationship between temperature and coefficient of thermal expansion of various materials. Horizontal axis: Temperature ('C,) Vertical @: Coefficient of thermal expansion ('C) Patent applicant Sumitomo Metal Mining Co., Ltd. II &('C)

Claims (1)

[Claims] MgO is 30% by weight or more, FeO is 13% by weight or less, C
A mold material for precision casting made by adjusting the particle size of granulated ferronickel slag with an aO content of 5% by weight or less to a maximum particle size of 5mm or less.