JPH04266457A - Casting mold for continuous casting - Google Patents

Abstract

PURPOSE:To prevent the erosion by the active components in molten copper and to produce a cast ingot having excellent quality by providing thin layers consisting of a specific material on the inside surfaces of the graphite casting mold. CONSTITUTION:The thin layers 1a consisting of the ceramics selected form zirconia, alumina, boron nitride or aluminum nitride are provided on the inside surfaces of a graphite casting mold body 1. The erosion by the active components, such as O, Zr, Cr, and Ti in the molten copper is prevented in this way and the copper or copper alloy contg. these components is produced with excellent quality.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for continuous casting of copper or copper alloys.

0002

[Prior Art] Conventionally, graphite or copper molds have been used as molds for continuous casting of copper or copper alloys, but when casting billets of small size (for example, φ20 mm or less), it is difficult to control solidification. Graphite is generally used as a mold material because of its good mold processability.

0003

[Problems to be Solved by the Invention] However, if graphite contains active ingredients in the molten copper, it will react with the ingredients and will be eroded over time, shortening its lifespan.On the other hand, the mold will be eroded. As the casting process progresses, the surface of the billet being cast becomes rough, and in severe cases, the billet seizes into the mold, resulting in minute cracks occurring on the billet surface.

[0004] Therefore, at present, the wire rods that can be cast using graphite molds are those that do not contain components that react with graphite in molten copper, such as oxygen-free copper, brass, various bronzes, cubronickel, deoxidized copper, silver, and gold. limited to.

On the other hand, in tough pitch copper, oxygen in the components is
In addition, in Zr-containing copper, Cr-containing copper, Ti-containing copper, etc., the Zr, Cr, and Ti components have a strong tendency to react with graphite and form carbides, making it difficult to cast billets of excellent quality using graphite molds. Met.

An object of the present invention is to eliminate the drawbacks of the prior art described above and provide a graphite-based mold that can be continuously cast even with molten copper containing active ingredients such as O, Zr, Cr, and Ti. It's about doing.

[0007]

[Means and operations for solving the problems] In order to achieve the above object, the present invention includes zirconia on the inner surface of the graphite mold.
A thin layer of alumina, boron nitride or aluminum nitride is provided, thereby eliminating O, Zr, Cr and T in the molten copper.
This prevents corrosion caused by active ingredients such as I, and makes it possible to produce superior quality ingots of copper or copper alloys containing these ingredients.

[0008] The materials for forming the inner surface of the mold in the present invention (zirconia, alumina, boron nitride, aluminum nitride) are all inert to O, Zr, Cr, Ti, etc. in molten copper, and are chemically It is also stable in terms of mechanical strength. Also. These substances are not only pure substances, but also contain trace amounts of additives as long as their chemical stability and resistance to molten copper flow (so-called lotion resistance) are not impaired. It's okay.

[0009] These materials for forming the inner layer generally have considerably poorer thermal conductivity than graphite, and are therefore susceptible to thermal shock and tend to be easily destroyed by rapid temperature changes.

[0010] Therefore, the thickness of the material for forming the inner layer is preferably as thin as possible, for example, at most 0.2 mm, preferably 0.02 mm or less.

[0011]

[Example] Example 1 A mold made of a graphite hollow material with an inner diameter of 10 mm, an outer diameter of 20 mm, and a length of 70 mm, and a mold in which a zirconia layer with a thickness of 0.15 mm was formed on the inner surface of a graphite hollow material of the same size was prepared,
Each mold was then combined with a water-cooled copper jacket (see Figure 1), and molten copper of Cu - 0.13% Zr was heated to a temperature of 1120°C.
It was continuously cast to a diameter of 10 mm at a temperature of 300 mm/min at a temperature of 300 mm/min. As a result, in the case of pure graphite molds, the solidified shell and the mold are baked in just one hour due to the reaction between the inner surface of the mold and the molten copper, resulting in minute cracks on the surface of the ingot. Many occurred. On the other hand, the life of the graphite mold with a thin layer of zirconia formed on its inner surface was significantly improved, with microcracks appearing only after about 5 days (120 hours) of continuous casting.

Example 2 In the same manner as in Example 1, a thickness of 0.15 mm was formed on the inner surface of the graphite hollow material.
A mold in which alumina of 1.0 mm thick was formed was prepared and tested in the same manner as in Example 1. As a result, only after about 4 days (96 hours) of continuous casting, minute tortoise lines were generated in the cast material, and as in Example 1, the mold life was significantly improved compared to the pure graphite mold.

Example 3 In the same manner as in Example 1, a thickness of 0.15 mm was formed on the inner surface of the graphite hollow material.
A mold containing 1 mm of boron nitride was prepared and tested in the same manner as in Example 1. As a result, approximately 3.5 days (84 hours)
Microcracks appeared only after continuous casting of the mold, showing superior mold life compared to pure graphite mold.

Example 4 As in Example 1, a thickness of 0.15 mm was formed on the inner surface of the graphite hollow material.
A mold with an aluminum nitride layer formed thereon was prepared and tested in the same manner as in Example 1. The results showed an excellent mold life of about 4 days (96 hours).

Example 5 C was applied to the inner surface of a graphite hollow material of the same size as that of Example 1.
Thin films (3 μm thick
) were used to perform continuous casting tests in the same manner as in Example 1, and the results showed excellent mold life of 7 days, about 6 days, about 10 days, and about 8 days, respectively. In this way, since the CVD thin film has excellent adhesion to graphite and forms a dense film, the life of the mold is dramatically improved.

[0016]

[Effects of the Invention] As explained above, according to the present invention, O
, Zr 2 , Cr 2 , Ti, and other active ingredients can be continuously cast.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a continuous casting mold of the present invention.

[Explanation of symbols]

1　Mold body 1a Ceramic thin layer 1b Graphite 2 Water-cooled copper jacket

Claims (1)

[Claims] Claim 1: A mold for continuous casting of copper or copper alloy,
A continuous casting mold characterized in that the base material is made of graphite, and the inner surface of the mold that comes into contact with molten copper is made of a thin layer of zirconia, alumina, boron nitride, or aluminum nitride.