JP2001322869A - Aluminum melting implement and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum melting implement which is excellent in corrosion resistance and thermal impact resistance and is hardly wettable with molten aluminum. SOLUTION: A molding consisting of 85 to 100 mass % α Spodumene and/or Petalite and 1 to 15 mass % auxiliary raw material is fired at 1,000 to 1,380 deg.C, by which the aluminum melting implement containing 85 to 100 mass % βSpodumene and consisting of ceramics is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jig for molten aluminum and a method for manufacturing the same.

[0002]

2. Description of the Related Art Aluminum products such as die-casting are 70%.
It is manufactured by casting aluminum melted at about 0 to 800 ° C. At this time, float, spout, nozzle,
Various jigs, such as a ladle, a header, a tub, etc., that are directly contacted by the molten aluminum are required. These jigs for molten aluminum require requirements such as excellent thermal shock resistance, poor wettability to aluminum (not wet / hard to wet), and excellent corrosion resistance.

Conventionally, metal products have been used. However, problems such as a short life in terms of corrosion resistance, and in particular, in the case of high-purity aluminum products, contamination of aluminum products with impurities have been a problem. I was

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a molten aluminum jig which has improved corrosion resistance, which has been a problem in conventional metal products, has excellent thermal shock resistance, and is hardly wetted by molten aluminum. And

[0005]

According to a first aspect of the present invention, there is provided a molten aluminum jig made of a ceramic having β-spodumene as a main constituent phase.
It is characterized in that it contains 85 to 100% by mass of β-spodumene (claim 2).
It is obtained by firing a molded body composed of 5 to 100% by mass and 0 to 15% by mass of auxiliary materials at 1000 to 1380 ° C (Claim 3).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The molten aluminum jig of the present invention is made of ceramics having β-spodumene as a main constituent phase. β
Spodumene is generally known for its low thermal expansion, and is excellent in thermal shock resistance due to this low coefficient of thermal expansion. It has been found that it not only has a sufficient thermal shock resistance to molten aluminum at up to 800 ° C., but also has excellent wettability and corrosion resistance, and can be suitably used as various aluminum molten jigs.

[0007] As a component other than β-spodumene, an unavoidable impurity component may be contained in an amount of about several mass%. Various oxide raw materials may be contained as long as they do not react. Especially β wollastonite,
It can be used preferably because it plays a role as a sintering aid without reacting with β-spodumene and has the effect of easily making β-spodumene dense. Although the thermal shock resistance is lowered by containing the β wollastonite in a predetermined amount, an appropriate amount can be mixed and used because the material becomes denser and the corrosion resistance and strength are improved. From such a viewpoint, the compounding amount that can be preferably used as a molten aluminum jig without impairing the thermal shock resistance, wettability, and corrosion resistance is that the β-spodumene is 85 to 100% by mass, and the β-spodumene is less than this. This is not preferable because the thermal shock resistance is greatly reduced.

When β-spodumene is 100%, it is difficult to obtain a dense ceramic,
There is no particular inconvenience regarding thermal shock resistance and aluminum wettability. However, in a part where the flow of the molten aluminum is severe and corrosion resistance is a problem, dense ceramics may be preferable. From such a viewpoint, a more preferable range of the content of β-spodumene when corrosion resistance is particularly required is 90 to 98% by mass.

[0009] Such a molten aluminum jig mainly composed of β-spodumene is composed of 85 to 100% by mass of α-spodumene and / or petalite as raw materials and 0 to 100% of auxiliary materials.
It is obtained by firing a molded body consisting of 15% by mass at 1000 to 1380 ° C. α-spodumene is transformed into β-spodumene by firing. Petalite also becomes a β-spodumene solid solution by firing. Of course, there is no problem if a β-spodumene raw material is used as a starting material, but α-spodumene and petalite are preferred in that raw materials can be obtained at lower cost. Since α-spodumene and petalite are natural raw materials, they often contain several mass% of impurities, but there is no problem in use as described above.

As the lithium aluminosilicate constituting the sintered body, a plurality of lithium aluminosilicates can be considered in addition to β-spodumene. For example, Li
Β-spodumene having a ratio of ₂ O: Al ₂ O ₃ : SiO ₂ of 1: 1: 4 is other than β-spodumene, other than 1: 1: 2 eucryptite, 1: 1: 6 lithiafeldspar, etc. Any of lithium aluminosilicate crystal mineral, lithium aluminosilicate crystallized glass and the like can be used. However, the fact that raw materials can be obtained at low cost as described above makes α
It is most industrial to bake spodumene and petalite to form β-spodumene and β-spodumene solid solution.

As the auxiliary material, any material can be used as long as it does not react with β-spodumene. However, as described above, it does not react with β-spodumene and plays a role as a sintering aid. Β wollastonite is preferred because it has the effect of easily making β-spodumene dense. As β-wollastonite, there are various types such as natural minerals containing several mass% of impurities and calcined calcium silicate hydrates, and any of them can be suitably used. Beta wollastonite minerals are most preferred. In addition, as a calcium silicate which transforms to β wollastonite, alit, berit, CSH, tobermorite, zonotlite, and other calcium silicate crystal minerals, crystal hydrates, amorphous hydrates and the like are also used.

The above-mentioned raw material compact is heated at 1000 to 1380 ° C.
And a molten aluminum jig is obtained. The firing conditions also depend on the specific gravity of the molded body before firing, the raw material particle size, and the mixing ratio,
If the firing temperature is lower than 1000 ° C., the sintered body is not densified and has low strength, which is not preferable. On the other hand, if it exceeds 1380 ° C., it is not preferable because it melts.

Hereinafter, the present invention will be described with reference to specific examples and comparative examples. (Examples 1 to 5) α-spodumene which is a natural mineral as a starting material (Li ₂ O: 7.5% by mass, Al ₂ O ₃ : 2)
5.0 mass%, SiO _2: 62.5% by weight, other:
5.0 mass%), petalite (Li ₂ O: 4.2 mass%, Al ₂ O ₃ : 16.6 mass%, SiO ₂ : 76.8 mass%, others: 2.4 mass%), β wollastonite (CaO: 44.6 wt%, SiO _2: 51.0 wt%, other: 4.4 wt%) by a predetermined amount, weighed in the raw material composition shown in Table 1 was water in the dispersion medium It was wet-pulverized with a ball mill to an average particle size of 2.0 μm. 2% by mass of PVA was added as a binder to the slurry, and the mixture was granulated with a spray drier, and then placed in a mold to produce a molded body at 1 ton / cm ² . The temperature is raised to a predetermined temperature at a rate of 5 ° C./min,
After holding for 1 hour, the furnace was cooled to obtain a sintered body. In Table 1, αS
P is an abbreviation for α-spodumene, βWO is for β wollastonite, and PT is for petalite. Example 5
Mix equal amounts of alpha spodumene and petalite and mix
% By mass.

(Evaluation method) 50 × 50 ×
A sintered body of 5 mm was prepared, and 1
After immersion for 00 hours, cracking due to thermal shock, wettability to molten aluminum, and corrosion resistance were evaluated. The thermal shock resistance was evaluated by the presence or absence of cracks when immersed in or taken out of the molten aluminum, and the wettability was determined by removing the aluminum film attached to the surface after removal from the molten aluminum. The evaluation was performed by judging whether the sample was peeled off from the base material and confirming the surface of the sample by microscopic observation. The corrosion resistance was evaluated by measuring the mass of the sample after evaluating the wettability and reducing the mass from the sample before immersion in the molten aluminum. Table 1 shows the obtained results.
Shown in The main crystal phase of the obtained sintered body was confirmed by powder X-ray diffraction. The results are also shown in Table 1. Example 2 was β-spodumene, and the others were β-spodumene and β-wollastonite. Here, βSP in Table 1 is an abbreviation for β-spodumene.

(Comparative Examples 1 to 4) Comparative Examples 1 to 3 are outside the scope of the present invention. At a predetermined temperature to obtain a sintered body.
Comparative Example 4 evaluated cast iron as a conventional example.

[0016]

[Table 1]

From the evaluation results shown in Table 1, it can be seen from Examples 1 to 4 of the present invention.
No. 5 did not crack by thermal shock even when immersed in molten aluminum, and was excellent in thermal shock resistance. Also,
Since all of these materials were hardly wet, they were easily peeled off from the adhesion interface, and no partial destruction of the base material due to wetting was observed under a microscope. Further, little change in mass was recognized, and it was determined that the material had excellent corrosion resistance. From the above, it was confirmed that these samples were excellent as a molten aluminum jig.

On the other hand, Comparative Examples 1 to 3 which are outside the scope of the present invention
In Comparative Example 1, cracks were generated by thermal shock, Comparative Example 2 was porous and had low strength and poor corrosion resistance. In Comparative Example 3, the sintered body was melted, It was unsuitable as a tool. Comparative Example 4 was extremely poor in corrosion resistance.

[0019]

According to the present invention, it is possible to produce a molten aluminum jig which is excellent not only in thermal shock resistance and hardly wet by molten aluminum but also in corrosion resistance and has a long life as a jig.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B22D 17/30 C04B 35/18 A C04B 35/195 B

Claims (3)

[Claims] 1. A molten aluminum jig made of ceramics having β-spodumene as a main constituent phase. 2. An amount of 85 to 100% by mass of β-spodumene.
The molten aluminum jig according to claim 1, wherein the jig is contained. 3. The molten aluminum according to claim 1, wherein a molded body composed of 85 to 100% by mass of α-spodumene and / or petalite and 0 to 15% by mass of an auxiliary material is fired at 1000 to 1380 ° C. Jig manufacturing method.