JPH11116336A - Graphite crucible - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a graphite crucible contriving to control the crack generation of the graphite crucible by thermal shocks, inhibit the corrosion of the graphite crucible due to a melted metal or slag, and elongate the life of the graphite crucible by adding the coarse particles of a heat-resistant aggregate except the graphite to a graphite crucible for dissolving the melted metal. SOLUTION: This graphite crucible is obtained by adding the coarse particles of a refractory aggregate 4 excluding the graphite 3 and having a particle diameter of 1/20 to 1/2 based on the wall thickness of the graphite crucible to the graphite 3 for the graphite crucible for dissolving a melted metal in an amount of 5-50 wt.% based on the total amount of the refractory aggregate. At least one of alumina, magnesia, zirconia, zircon, spinel, silica, mullite, titania, feldspar, dolomite, sillimanite and silicon carbide is used for the coarse particles of the refractory aggregate 4 excluding the graphite. It is preferable that an aggregate optimal for the melted metal is used. All of a potter's wheel molding method, a hydraulic pressure molding method, a friction molding method, a static pressure molding method and the like can be applied to a method for forming the graphite crucible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement in a graphite crucible used for melting and refining molten metal.

[0002]

2. Description of the Related Art Generally, graphite 3 and refractory aggregate 4 are used in a graphite crucible for molten metal. Graphite 3 is hardly wetted by molten metal and has a high thermal conductivity and a low elastic modulus, so it is very effective against erosion resistance and thermal shock. Among them, flaky natural graphite is particularly high in thermal conductivity and low elasticity. Natural graphite is used in many refractories because of its rate.

As the refractory aggregate 4 other than graphite, those having the most suitable chemical composition exhibiting corrosion resistance to various molten metals or slags are used. For example, for melting steel and cast iron, alumina, magnesia, zirconia, zircon,
Aggregates such as spinel, silicon carbide for dissolving aluminum, and alumina and silicon nitride for dissolving copper.

Fine particles of the refractory aggregate 4 other than the graphite 3 are mainly used to improve the strength of the graphite crucible 1. However, when the refractory aggregate is fine particles, the cracks are easily developed along the flaky graphite layer when subjected to thermal shock, and the refractory aggregate particles easily flow down to the molten metal and slag. there were. The structure of the conventional graphite crucible 1 is shown in FIGS.

[0005]

As described above, when fine particles are mainly used as a refractory aggregate of a graphite crucible, crack resistance,
This leads to a decrease in erosion resistance, and it is difficult to extend the life of the crucible.

According to the present invention, by adding coarse particles of the refractory aggregate 4 to a graphite crucible for melting molten metal, it is possible to suppress cracking of the graphite crucible due to thermal shock and erosion due to molten metal or slag. And to provide a graphite crucible 2 having a high life. The structure of the graphite crucible 2 of the present invention is shown in FIGS.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is characterized in that coarse particles are added as a refractory aggregate 4 other than graphite 3 of a graphite crucible 2. This is a graphite crucible 2 having improved thermal shock resistance and erosion resistance.

Next, if the proportion of the coarse particles of the refractory aggregate 4 other than graphite is less than 5% by weight, there is almost no effect on thermal shock. On the other hand, if the content is 50% by weight or more, the strength of the graphite crucible decreases, and the graphite crucible becomes weak against mechanical impact.

Next, if the coarse particle size of the refractory aggregate 4 other than graphite is less than 1/20 of the thickness of the graphite crucible, when the crack occurs, the crack easily develops along the graphite layer, which is not effective. thin. On the other hand, if the ratio is 1/2 or more, the thermal characteristics (low thermal conductivity, high thermal expansion, etc.) of the coarse particles become large, and the characteristics of a graphite crucible using graphite cannot be utilized.

Next, as the refractory aggregate 4 other than graphite, it is preferable to use an aggregate most suitable for the metal to be melted.

The method for molding the graphite crucible of the present invention is applicable to all methods such as rotomolding, hydraulic molding, friction molding and hydrostatic molding.

[0012]

Example 1 A graphite crucible 2 of the present invention was used in a 500 kg heavy oil melting furnace for copper alloy. Table 1 shows the results. The product of the present invention was good with little erosion even with 100 ch and no cracking.

[0013]

Example 2 A graphite crucible 2 of the present invention was used in a 1000 kg induction furnace made of cast iron. Table 2 shows the results. The product of the present invention is 2
Even at 00 ch, there was little erosion, and there was no cracking, and it was good.

[0014]

The product of the present invention is a graphite crucible for melting molten metal using coarse particles of refractory aggregate other than graphite, which can suppress cracking due to thermal shock and erosion due to molten metal or slag. The life of the crucible was extended.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the structure of a conventional graphite crucible.

FIG. 2 is a partially enlarged sectional view of a conventional graphite crucible.

FIG. 3 is a sectional view showing the structure of the graphite crucible of the present invention.

FIG. 4 is a partially enlarged sectional view of the graphite crucible of the present invention.

[Explanation of symbols]

 1,2 graphite crucible 3 graphite 4 refractory aggregate other than graphite

[Table 1]

[Table 2]

Claims (4)

[Claims] 1. In a graphite crucible for melting molten metal, coarse particles of refractory aggregate other than graphite are added in order to suppress crack generation due to thermal shock and to suppress erosion by molten metal or slag. A characteristic graphite crucible. 2. The graphite crucible for melting molten metal according to claim 1, wherein the addition amount of coarse particles of the refractory aggregate other than graphite is 5 to 50% of the total weight ratio of the refractory aggregate. 3. As coarse particles of refractory aggregate other than graphite,
2. A graphite crucible for melting molten metal according to claim 1, wherein a refractory aggregate having a particle diameter of 1/20 to 1/2 of the thickness of the graphite crucible is used. 4. As coarse particles of refractory aggregate other than graphite,
Alumina, magnesia, zirconia, zircon, spinel, silica, mullite, titania, feldspar, dolomite,
2. The graphite crucible for melting molten metal according to claim 1, wherein at least one of sillimanite and silicon carbide is used.